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LIVE – Afternoon Session added – Gene Therapy Development & Cell Therapy Bioprocessing – Overcoming Scientific and Development Challenges @Biotech Week Boston, October 5, 2016 Boston Convention and Exhibition Center

Posted in CANCER BIOLOGY & Innovations in Cancer Therapy, Cell Processing System in Cell Therapy Process Development, Conference Coverage with Social Media, Gene Therapy & Gene Editing Development, Genome Biology on October 5, 2016| Leave a Comment »

LIVE – Afternoon Session added – Gene Therapy Development & & Cell Therapy Bioprocessing – Overcoming Scientific and Development Challenges @Biotech Week Boston, October 5, 2016 Boston Convention and Exhibition Center

#BiotechWeekBoston

 avivalev-ari@alum.berkeley.edu

@pharma_BI

@AVIVA1950

ANNOUNCEMENT

Leaders in Pharmaceutical Business Intelligence (LPBI) Group, Boston

pharma_bi-background0238

will cover in REAL TIME

Biotech Week Boston, October 5, 2016 @ Boston Convention and Exhibition Center

 

In Attendance, streaming LIVE using Social Media

Aviva Lev-Ari, PhD, RN

Editor-in-Chief

http://pharmaceuticalintelligence.com

 

Gene Therapy Development & Production

&

Cell Therapy Bioprocessing – Innovations in Cell Processing – Part 1 & 2

Gene Therapy Development & Production

8:25 am 5 mins

Chairperson’s Opening Remarks

8:30 am 30 mins

Extended Range and Next Generation Chimeric Antigen Receptor T Cells

  • Bruce Levine, Ph.D., Barbara and Edward Netter Associate Professor in Cancer Gene Therapy, University of Pennsylvania

ALL

  1. Lymphoeid Leukemia –  Persisting CTL019 Cells remains – Pediatrics ALL – Relapsed and Refractory B-celll
  2. Bedside back to Bench lessons: Days post infusion
  3. 28 days vs 51 cells
  4. quality of cells: related to Clinical Response
  5. 93% CR rate for r/r ALL after CTL019
  6. Novartis and UPenn Cell Center Building

LIMPHOMA

  1. Diffuse Large B Cell Lymphoma
  2. Engineered T Cells and CHeckpoint ANtibody Therapies: Potential Synergies
  3. Days post-tumor injection: Non-responding patients: infusion of PD1 Inhibitor
  4. After treatment: Durable responses necrosis no tumor left
  5. Single Arm, Open-Label

MYELOMA

  1. CART19
  2. CART BCMA – cells for Multiple Myeloma – Bone Marrow: Pre-treatment 70% myeloma cells
  3. Ibrutinib enhances chimeric antigen receptor T-cell engraftment and efficacy in Leukemia
  4. Synthetic Biology – Penn Platform Technology: Academic CAR Clinical Trials
  • Academic-Industry COllaboration with Novartis: Human Cell Therapy: 1996-2011
  • FromGene therapy to >>> Immunotherapy, to >>>>>> Gene Editing
  • TMUNITY – new mission with Leukmia and Lymphoma Foundation

9 am30 mins

Novartis Pharma: Stabilizing Lentiviral (LV) vector formulation for CART Application

  1. LV development of Vector Production – for Ex-vivo Therapy
  2. mamamalian cells + plasmid
  3. high titer, sequences liability &FTO
  4. PROCEESS
  • aggregation
  • Trunsduction
  • purification –
  • Phys-chem profile,
  • stable – – Stability in buffers for recovery of infectious particles – Purification
  • low cost
  1. LV: Optimize transient production:
  • EARLY PROCESS-CHECK,
  • FORMULATION SCEEEN – Preformulation of LVs: Drug DIscovery
  • ANALYTICS DEVELOPMENT
  • TECHNICAL-GRADE VECTOR SUPPLY
  1. High throughput screen
  2. stability promoting buffers
  3. stability in process intermediates
  4. Attributes: Preformulation – success criteria – stable in transduction media/conditions’minimal loss of infectious particles
  5. LV with Transgene 1Preformulation: Effect of buffer and salts – 96 different conditions (buffer +salts)
  6. LV Aggregation & Loss of Infectivity – Accelerated Stree Studies
  7. Size Interpretations – Dynamic Light scattering (DLS): Buffer A, E, H
  8. Robustness: Preformulation buffers: Small, Medium, Large Rh:
  • pH 6.0 – 8.5 – X axis and
  • Salt 0 – 200nM – V Axis

9. Freeze-Thaw Studies – Accelerated Stress Studies: w/o Carbohydrate

  •  number of Freeze-thaw cycles X axis vs
  • % Control to standard – V Axis  

10, Infectious Titer: Primary T Cells

Case study: LV with Transgene #2 –

  • Platform formulation for LV is possible
  • Transduction in primary T cells showed high titer and minimal toxicity
  • stability studies of in-process intermediates and LV-DS provided additional evidence
  • 4 promising conditions identified for preformulation of LV vectors from HTS screens

 9:30 am 30 mins

Mesenchymal Stem Cells (MSCs) on Steroids

  • Oren Levy, HMS, Brigham and Women’s Hospital
I. Mesenchymal Stem Cells – readily accessible potent immunomodulatory secretome already used in >600 clinical trials
  1. Uncontrolled cargo’Inefficient targeting to disease sites – A microparticle-based cellular
  2. Particle-in-a cell approach in Prostate Cancer: PSA – Thapsigargin – PLGA – Poly Lactic co Glycol Acid – encapsulated agent’The cellular carriers MSCs
  3. Glioblastoma, Prostate
  4. Drug-loaded MSCs kill prostate cancer cells
  5. Drug release from G114 MP-loaded cells
  6. MDA-MB; LNCaP – Coculture with pretreated MSCs
  7. Drug-loaded MSCs inhibit tumor growth: days post-inoculation vs Probabilirt of Tumor-free SUrvival vs. Tumor Volume
  8. Particle Payloading: Boosting Potency of Administrated Cell Populations – for Drug delivery
  9. Controlled inhibition of the MSC proinflammatory
  10. Donor variability leads to Functional Variability – variability between 7 donors
  11. Budesonide microparticles boosted MSC
  12. Improved imaging of transplanted MSCs
  13. Retention of PLGA
  • MSC: Therapy
  • Betacells – Islet transplantation Macrophages – immunotherpy

II.  Targeting cells to disease site – Surface of MSC – lacks standard “homing”

  • tetharing – rolling – firm adhesion – transmigration- endothelial cells, basement membrane: Healthy vs Inflammed
  • lucocytes
  • Controlling MSC fate via small molecule pretreatment
  • RNA transfection
  • Bone marrow: PSGL-1/SLex MSCs exhibit enhanced homing to healthy and irradiated bone marrow
  1. A multi-step screening platform for identification of small molecules that improve MSC homing: Surface expression, FIrm adhesion, MSC homing
  2. A medium throughput screen identified Ro-31-8425
  3. Upregulated of CD11a, in response to pretreatment  increases MSC firm adhesion
  4. Pretreated MSCs exhibit superior therapeutic impact post systemic adm – suppression of local skin inflammation
  5. Ro-31-8425 Treated MScs va Vehicle treated MScs
  6. boosted clinical impacet in a MS Model
  7. Bradly applicable cell-based therapeutic platform
  8. mRNA transfection
  9. drug microparticles

 

Gene Therapy Development & Production – Emerging Research: Delivery Strategies and Genome Engineering Technologies

10:30 am30 mins

Genetic Engineering Red Blood Cells for Therapeutic Function

  •  
    Robert J. Deans, Ph.D.,Chief Scientific Officer, Rubius Therapeutics
  • Rubius Therapeutics – Whitehead Institute/DARPA legacy
  • Flagship Venture founded
  • RCTs – development of ALternative Therapeutics
  • Platfoms: Transfusion /donor selection, risk of oncogenicity – uncontrolled division and secretion
  • Allogenic RCTs grown in Culture from Hemopoeitic Stem Cells (HSCs) In vitro and engineered to Purpose along the way
  • Expansion: CD34 + HSCs: Mobilized, cord blood
  • Cytoplasm: Native cytoplasmic, Tethered cytoplasmic , tethered surface native surface
  • Visualizing Red Cell Therapeutics – RCT during differentiation
  • Reliablly use cell surface markers to track the cells as hey differentiate
  • Flow Cytometry
  • Automated platform foe creating Master cell BioBank
  1. Apheresis Transduction
  2. clinical scale
  3. Rapid prototyping capability for candidate Selection, Vector generation, Human CD34+
  4. Prototyping for Pipeline
  5. Exogenous protein is retained: Cultured RBCs circulating in vivo like Human RBCs
  6. Experimental Setup: RCT circulation in similar to HuRBCs
  7. RCTs can possess antibody drugs on their surface for clearance and therapeutic action
  8. Target: scFv antiVirusAg – capture circulating antigen in vitro and in vivo – Virus Antigen – label antibody
  9. Phenylketonuria (PKU) – CNS morbidity from Serum PHE – it is easily measured, gold standard diagnostic and clinical biomarker
  • Novel protein, cell & gene therapy treatment
  • Existing PAL-RBCs have clinical grade potency at currently achievable manufacturing scale: Serum PHE vs Units PAL-RBS IRON
  • dose dependent PHE expression

 

11 am30 mins

Novel Approaches to Gene Editing and Gene Delivery 

In Vivo gene therapy

  •  
    Andrew Scharenberg, M.D.,Professor of Pediatrics, Adjunct Immunology / Co-director, Program in Cell and Gene Therapy, University of Washington / Seattle Children’s Research Institute
  1.  Viral vector tranfer
  2. cell mediated immunity
  3. Humoral immunity
  4. Evasion/tolerance – neonatal adm of vector
  5. Challenges: Unmet need Goal – Primary cell: DNA delivery to nucleus
  • Cells have mupliplr mechanisms to prevent foreign DNA from entering the nucleus
  • Viruses evade these mechanisms

Non-enveloped Virions – classic gene therapy vector AAV

  • Viral capsid serves multiple roles:
  • AAV has no mechanism to neutralize nuclear silencing mechanism

Enveloped Virions: Retro and Lenti-Virus

Re-dosable in vivo gene transfer

LNP’s mimic the endosomal uptake and escape functions of AAV Capsid

  • mRNA delivery to build a capsid “life boat” – reverse transcribe the gemone and send it in
  • RNA packing, minus strand systhesis, plus strand synthesis, budding, ER vesicular transport ENTRY repair

HBV-based Non-Viral RNA Gene Transfer System: Electric Poration (EP) or LNP

Pregenomic (pgRNA) Vector RNA architecture

  1. Viral RNA – Pol transfers to 3′ DR1 for _ strand sysnthesis
  2. Vector RNA – payload cap… pA
  3. pgRNA with GFP cassette flanked by SB Tn sites – Inhibition and Translation areas
  4. BFP vs GFP
  5. Validation of pgRNA reverse transcription: HepG2 cells transfected with indicated RNAs plus POL/CORE/X mRNAs, then cultured for 2 weeks
  6. Plasma DNA vs Tn-pgRNA, Tn-pgRNA + 5B vs COntrol
  7. pgRNA/SB achieves stable luciferase expression
  8. No-Viral RNA Gene Transfer System: Status and Future
  9. Encouraging evidence of functional synthetic recycling RT vector: SERT – Synthetic encoded reverse transcription)
  10. Transposon IR/DR – flaked pgRNA payload

 

11:30 am30 mins

Development of Stem Cell Derived Extracellular Vesicles into a Non-Living Regenerative Therapeutic Drug Candidate

  •  
    Keil  Ph.D., Capricor, Inc.

Gene Therapy Development & Production – Manufacturing Strategies and Solutions for Gene Therapies

  1. Cardioshere-Derived Cells – DOnors of cells – Primary cardiac tissue’Key functions – paracrine:
  2. CDC Manufacturing
  3. DOnor Heart from organ procurement —
  4. Cell Therapy: Autologous vs Allogenics
  5. Cell engraftment
  6. Autologous vs Allogenics Clinical Trials:
  7. Caduceus vs Dynamic
  8. Scar tissue

What are exosomes? as a therapeutics

  • rich in RNA
  • CDC EVs: By the numbers
  • Exosomal Markers vs CDC Marker – CD 105

Acute MI Model

  • Viable mass increased, Myocyte size increased, EF increased,
  • Identified 146a as a major player in cardio-protection
  • CAP2003 manufacturing Process
  • CDC-EV Manufsacturing Overview vs CDC Product
  • Conditioned Medium collection
  • day 1 vs 15 days
  • Drug Product Formulation
  • Choosing a Formulation Buffer: pH
  • 30 days stability
  • Process Robustness: Particle Size and pH: 4 diffrent donors (variability is related to culture and to patients) – 10 formulation runs: EV size vs diafiltrate pH (average =7)
  • Process Robustness: Concentration and Cargo
  • Human mir panel v3.0
  • nCounter miRNA analysis
  • Particle foes not increase linearly with protein
  • Process Robustness: miRNA 146 & 210
  • Process Impurities & Residual: Residual  Fibronectin in CM vs BSA wash-out
  • CDC-EVs have anti-apoptotic, anti fibrotic, immunomodulatory and pro-regenerative activities similar to CDCs
  • New indications
  • Pathway to iND: Pre-Clinical Efficacy
  • Average Total clinical Score
  1. conjunctival injection
  2. corneal opacification
  3. corneal area affected
  4. corneal neovascularization
  5. aqueous flare
  6. Ongoing Pre-Clinical: biodistribution,
  7. Upscaling Exosomes: Bioreactor CDCs
  8. Current Process vs Target Process

Next Gen Storage: Lyophilization (Astraunatu EV

State of Capricor’s Art

 

Cell Therapy Bioprocessing – Innovations in Cell Processing – Part 2

 

2:10 pm 5 mins

Chairperson’s Remarks

 

2:15 pm30 mins

CAR T production in G-Rex: Less is More

  •  
    Juan Vera, M.D., Associate professor Center for Cell and Gene Therapy, Baylor College of Medicine., Baylor College of Medicine
  • Adoptive T-cells Transfer
  • Donor Lymphocytes blood draw — antigen specificities == cell expansion == infusion back to aptient – antigen specific T-cells to iincrease immunogenecity
  • Low seeding density results in greater fold expansion
  • Low cell density + Greater cell expansion: Optimal time for cell harvest vs maximum cell density
  • Volume of Media vs Cells density
  • Upfront media addition resulted in shortest culture period
  • Conventional cultureware  – risk for contamination
  • G-Rex – Plate vs G-Rex – G-REX 5; G-Rex 100; G-REX -500 (flacks)
  • superior cellnumber not due to increase cell number – improved cell output
  1. phase 1 – what is optimal seeding density – cells expansion in 12 days
  2. phase 2 – optimal volume in media – I=1L
  3. phase 3 –
  • are observations reproducible?
  • Cell harvest with The GatheRex – in 5 minutes you collect one billion cells (density
  • CAR-T cells: Preparation of genetically-modified T cells
  • PSCA – solid Tumor
  • NT T cells – suppress tumor cells by immunoresponse to antigen specific to CAR-T
  • CAR-T cell expansion in G-REX – day in culture vs Glucose concentration – inverse correlation
  • Cell performance of production of CAR=t in G-REX
  • Phynotype of CAR-T cells: 24 wells vs G-REX
  • CCR7 vs CD62L: Conventional vs G-REX  – superior Phynotype of CAR-T Cells expanded inside G-REX
  • stimulation beads = not used i=with G-REX
  • media vs cell ratio – serology
  • Persistance of CAR-T cells 6 month post transfer – rechallenge the cells ramping up withstand multiple re-challenge
  • Post transfection – transduction 3 days after

2:45 pm40 mins

Approaches for Determining Technologies to Pursue for Cell Therapy Bioprocessing

  • Brian Murphy, Ph.D., Director of Development, Celgene Cellular Therapeutics

Celgene cellular therapy

  • PDA-002 -MSC
  • PNK-007 – NK cells
  • TST-001
  • GM-
Technologies – CMC Feasibility: make enough cells, the right phynotypes make them GMP – secure cell supply
  • preclinical
  • Phase 1
  • phase 2
  • phase 3 – commercial: Controllable, scaleable, compliant, cost-effective

Scale up: Phase appropriate under scale or over scale vs utilization

  • TIPS: Cell experience need be controlled
  • Static culture technology vs suspension culture
  • Stability in media
  • metabolite
  • Biology Informs Technology: Control critical parameters vs Failure mode
  • After Biology – other factors:
  1. cost
  2. capacity

PDA-002 – Two tier banking system for Cell therapies – adherent cells grown in suspension or microcarriers

Growth on microcarriers in Bioreactor

  • innoculation efficacy
  • harvest formulation
  • fill
  • cryopresevation drug substance

Phase 2 – Process technology

Phace 3 – Process technology for Dose increase — Drug Product — Shipping Product

Biological needs of the cels: Day 11 Media x vs Media Y

Impact of a 35 day Culture — long process: Process duration, Trouble shooting Characterization:

  • 7 days,
  • 21 days
  • 35 days

 

PNK-007: Process Overview – sensitive at few time points in while grown in suspension

Supply Projection & Inventory: 1,2,3 years

Phase 1

phase 2

Phase 3

Conclusion Multiple Groups involved in Production

  • Bioprocess development
  • Stem cell research
  • Analytical development
  • Manufacturing Operations
  • Quality Assurance

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miRNA Therapeutic Promise

Posted in Biological Networks, CANCER BIOLOGY & Innovations in Cancer Therapy, Cancer Genomics, Cell Biology, Signaling & Cell Circuits, Gene Therapy & Gene Editing Development, Genomic Expression, interventional oncology, KRAS Mutation, Loss of function gene, Molecular Genetics & Pharmaceutical, mRNA, mRNA platform in Drug DIscovery, mRNA Therapeutics, RNA Biology, Cancer and Therapeutics, tagged , , , , , , , , , , , , on May 1, 2016| Leave a Comment »

miRNA Therapeutic Promise

Curator: Larry H. Bernstein, MD, FCAP

 

MicroRNA Expression Could Be Key to Leukemia Treatment

http://www.genengnews.com/gen-news-highlights/microrna-expression-could-be-key-to-leukemia-treatment/81252662/

MicroRNA Expression Could Be Key to Leukemia Treatment

Generalized gene regulation mechanisms of miRNAs. [NIH]

 

Increasingly, cancer researchers are discovering novel biological pathways that regulate the expression of various genes that are often strongly associated with tumorigenesis. These new molecular mechanisms represent important potential therapeutic targets for aggressive and difficult-to-treat cancers. In particular, microRNAs (miRNAs)—small, noncoding genetic material that regulates gene expression—have steadily become implicated in the progression of some cancers.

Now, researchers at the University of Cincinnati (UC) have found a particular signaling route for a microRNA, miR-22, that they believe leads to targets for acute myeloid leukemia (AML), the most common type of fast-growing cancer of the blood and bone marrow.

The findings from this study were published recently in Nature Communications in an article entitled “miR-22 Has a Potent Anti-Tumour Role with Therapeutic Potential in Acute Myeloid Leukaemia.”

Structure of mi-22 miccroRNA. [Ppgardne at el., via Wikimedia Commons]

Increasingly, cancer researchers are discovering novel biological pathways that regulate the expression of various genes that are often strongly associated with tumorigenesis. These new molecular mechanisms represent important potential therapeutic targets for aggressive and difficult-to-treat cancers. In particular, microRNAs (miRNAs)—small, noncoding genetic material that regulates gene expression—have steadily become implicated in the progression of some cancers.

Now, researchers at the University of Cincinnati (UC) have found a particular signaling route for a microRNA, miR-22, that they believe leads to targets for acute myeloid leukemia (AML), the most common type of fast-growing cancer of the blood and bone marrow.

The findings from this study were published recently in Nature Communications in an article entitled “miR-22 Has a Potent Anti-Tumour Role with Therapeutic Potential in Acute Myeloid Leukaemia.”

“MicroRNAs make up a class of small, noncoding internal RNAs that control a gene’s job, or expression, by directing their target messaging RNAs, or mRNAs, to inhibit or stop. Cellular organisms use mRNA to convey genetic information,” explained senior study author Jianjun Chen, Ph.D., associate professor in the department of cancer biology at the UC College of Medicine. “Previous research has shown that microRNA miR-22 is linked to breast cancer and other blood disorders which sometimes turn into AML, but we found in this study that it could be an essential anti-tumor gatekeeper in AML when it is down-regulated, meaning its function is minimized.”

AML—most common type of acute leukemia—arises when the bone marrow begins to make blasts, cells that have not yet completely matured. These blast cells typically develop into white blood cells; however, in AML the cells do not develop and are unable to aid in warding off infections. In the current study, the UC team describes how altering the expression of miR-22 affected AML pathogenesis.

“When we forced miR-22 expression, we saw difficulty in leukemia cells developing, growing, and thriving. miR-22 targets multiple cancer-causing genes (CRTC1, FLT3, and MYCBP) and blocks certain pathways (CREB and MYC),” Dr. Chen noted. “The downregulation, or decreased output, of miR-22 in AML, is caused by the loss of the number of DNA being copied and/or stopping their expression through a pathway called TET1/GFI1/EZH2/SIN3A. Also, nanoparticles carrying miR-22 DNA oligonucleotides (short nucleic acid molecules) prevented leukemia advancement.”

The investigators conducted the study using bone marrow transplant samples and animal models. The researchers showed that the ten-eleven translocation proteins (TET1/2/3) in mammals helped to control genetic expression in normal developmental processes. This was in sharp contrast to mutations that cause function loss and tumor-slowing with TET2, which has been observed previously in blood and stem cell cancers.

“We recently reported that TET1 plays an essential cancer generating role in certain AML where it activates expression of homeobox genes, which are a large family of similar genes that direct the formation of many body structures during early embryonic development,” remarked Dr. Chen. “However, it is unknown whether TET1 can also function as a repressor for cellular function in cancer, and its role in microRNA expression has rarely been studied.”

Dr. Chen added that these findings are important in targeting a cancer that is both common and fatal, stating that “the majority of patients with ALM usually don’t survive longer than 5 years, even with chemotherapy, which is why the development of new effective therapies based on the underlying mechanisms of the disease is so important.”

“Our study uncovers a previously unappreciated signaling pathway (TET1/GFI1/EZH2/SIN3A/miR-22/CREB-MYC) and provides new insights into genetic mechanisms causing and progressing AML and also highlights the clinical potential of miR-22-based AML therapy. More research on this pathway and ways to target it are necessary,” Dr. Chen concluded.

 

miR-22 has a potent anti-tumour role with therapeutic potential in acute myeloid leukaemia

Xi Jiang, Chao Hu, Stephen Arnovitz, Jason Bugno, Miao Yu, Zhixiang Zuo, Ping Chen, et al.
Nature Communications 26 Apr 2016; 7(11452).    http://dx.doi.org:/doi:10.1038/ncomms11452

MicroRNAs are subject to precise regulation and have key roles in tumorigenesis. In contrast to the oncogenic role of miR-22 reported in myelodysplastic syndrome (MDS) and breast cancer, here we show that miR-22 is an essential anti-tumour gatekeeper in de novo acute myeloid leukaemia (AML) where it is significantly downregulated. Forced expression of miR-22 significantly suppresses leukaemic cell viability and growth in vitro, and substantially inhibits leukaemia development and maintenance in vivo. Mechanistically, miR-22 targets multiple oncogenes, including CRTC1, FLT3 and MYCBP, and thus represses the CREB and MYC pathways. The downregulation of miR-22 in AML is caused by TET1/GFI1/EZH2/SIN3A-mediated epigenetic repression and/or DNA copy-number loss. Furthermore, nanoparticles carrying miR-22 oligos significantly inhibit leukaemia progression in vivo. Together, our study uncovers a TET1/GFI1/EZH2/SIN3A/miR-22/CREB-MYC signalling circuit and thereby provides insights into epigenetic/genetic mechanisms underlying the pathogenesis of AML, and also highlights the clinical potential of miR-22-based AML therapy.

 

As one of the most common and fatal forms of hematopoietic malignancies, acute myeloid leukaemia (AML) is frequently associated with diverse chromosome translocations (for example t(11q23)/MLL-rearrangements, t(15;17)/PML-RARA and t(8;21)/AML1-ETO) and molecular abnormalities (for example, internal tandem duplications of FLT3 (FLT3-ITD) and mutations in nucleophosmin (NPM1c+))1. Despite intensive chemotherapies, the majority of patients with AML fail to survive longer than 5 years2, 3. Thus, development of effective therapeutic strategies based on a better understanding of the molecular mechanisms underlying the pathogenesis of AML is urgently needed.

MicroRNAs (miRNAs) are a class of small, non-coding RNAs that post-transcriptionally regulate gene expression4. Individual miRNAs may play distinct roles in cancers originating from different tissues or even from different lineages of hematopoietic cells4. It is unclear whether a single miRNA can play distinct roles between malignancies originating from the same hematopoietic lineage, such as de novo AML and myelodysplastic syndrome (MDS). Although around 30% of MDS cases transform to AML, the genetic and epigenetic landscapes of MDS or MDS-derived AML are largely different from those of de novo AML5, 6. MDS and MDS-derived AML are more responsive to hypomethylating agents than de novo AML7. The molecular mechanisms underlying the distinct pathogenesis and drug response between MDS (or MDS-derived AML) and de novo AML remain unclear.

The ten-eleven translocation (Tet1/2/3) proteins play critical transcriptional regulatory roles in normal developmental processes as activators or repressors8, 9, 10. In contrast to the frequent loss-of-function mutations and tumour-suppressor role of TET2 observed in hematopoietic malignancies11, 12, 13, we recently reported that TET1 plays an essential oncogenic role in MLL-rearranged AML where it activates expression of homeobox genes14. However, it is unknown whether TET1 can also function as a transcriptional repressor in cancer. Moreover, Tet1-mediated regulation of miRNA expression has rarely been studied10.

In the present study, we demonstrate that miR-22, an oncogenic miRNA reported in breast cancer and MDS15, 16, is significantly downregulated in most cases of de novo AML due to TET1/GFI1/EZH2/SIN3A-mediated epigenetic repression and/or DNA copy-number loss. miR-22 functions as an essential anti-tumour gatekeeper in various AML and holds great therapeutic potential to treat AML.

 

The downregulation of miR-22 in de novo AML

Through Exiqon miRNA array profiling, we previously identified a set of miRNAs, such as miR-150, miR-148a, miR-29a, miR-29b, miR-184, miR-342, miR-423 and miR-22, which are significantly downregulated in AML compared with normal controls17. Here we showed that among all the above miRNAs, miR-150 and especially miR-22 exhibited the most significant and consistent inhibitory effect on MLL-AF9-induced cell immortalization in colony-forming/replating assays (CFA) (Supplementary Fig. 1a). In contrast to the reported upregulation of miR-22 in MDS16, our original microarray data17 (Fig. 1a,b) and new quantitative PCR-independent validation data (Supplementary Fig. 1b) demonstrated a significant and global downregulation of miR-22 in de novo AML relative to normal controls. Notably, miR-22 is significantly downregulated in AML samples (P<0.05) compared with all three sub-populations of normal control cells, that is, normal CD34+ hematopoietic stem/progenitor cells (HSPCs), CD33+ myeloid progenitor cells, or mononuclear cells (MNCs) (Fig. 1a). Expression of miR-22 is significantly downregulated in all or the majority of individual subsets of AML samples than in the normal CD33+ or CD34+ cell samples (Fig. 1b).

Figure 1: miR-22 inhibits AML cell transformation and leukemogenesis.

miR-22 inhibits AML cell transformation and leukemogenesis.

(a,b) Exiqon microRNA profiling assay showed that miR-22 is significantly (P<0.05) downregulated in the entire set of AML set (n=85) (a) or each individual subset (b), relative to normal controls. The expression data were log(2) transformed and mean-centred. Mean±s.e.m. values were shown. (c) Comparison of effects of in-house miR-22, miR-22_Song16 and miR-22 mutant (miR-22mut; see the mutation sequence at the top) on MLL-AF9-induced colony forming. CFAs were performed using mouse BM progenitor (Lin–) cells transduced with MSCV-neo+MSCV-PIG (Ctrl), MSCV-neo-MLL-AF9+MSCV-PIG (MLL-AF9), or MSCV-neo-MLL-AF9+MSCV-PIG-miR-22/miR-22_Song/miR-22mut. (d) Effects of miR-22 on the colony forming induced by multiple fusion genes. CFA was performed using wild-type BM progenitor cells co-transduced with MSCV-neo-MLL-AF9 (MA9), -MLL-AF10 (MA10), -PML-RARA (PR) or –AML1-ETO9a(AE9a)19, together with MSCV-PIG (Ctrl) or MSCV-PIG-miR-22 (+miR-22), as well as miR-22−/− BM progenitors co-transduced with individual fusion genes and MSCV-PIG. Colony counts (mean±s.d.) of the second round of plating are shown. *P<0.05; **P<0.01. (e,f) Effect of miR-22 on MLL-AF9-induced primary leukemogenesis. Kaplan–Meier curves are shown for six cohorts of transplanted mice including MSCVneo+MSCV-PIG (Ctrl; n=5), MSCVneo+MSCV-PIG-miR-22 (miR-22; n=5), MSCVneo-MLL-AF9+MSCV-PIG (MA9; n=8), MSCVneo-MLL-AF9+MSCV-PIG-miR-150 (MA9+miR-150, n=6), MSCVneo-MLL-AF9+MSCV-PIG-miR-22 (MA9+miR-22; n=10) and MSCVneo-MLL-AF9+MSCV-PIG-miR-22mutant (MA9+miR-22mut; n=5) (e); Wright–Giemsa stained PB and bone marrow (BM), and hematoxylin and eosin (H&E) stained spleen and liver of the primary BMT recipient mice at the end point are shown (f). (g) Effect of miR-22 on MLL-AF10-induced primary leukemogenesis. Kaplan–Meier curves are shown for two cohorts of transplanted mice including MSCVneo-MLL-AF10+MSCV-PIG (MA10; n=5) and MSCVneo-MLL-AF10+MSCV-PIG-miR-22 (MA10+miR-22; n=5). (h) miR-22 knockout promotes AE9a-induced leukemogenesis. Kaplan–Meier curves are shown for mice transplanted with wild-type or miR-22−/− BM progenitor cells transduced MSCV-PIG-AE9a (n=5 for each group). The P values were generated by t-test (a–d) or log-rank test (e,g,h).

To rule out the possibility that the inhibitory effect of miR-22 shown in Supplementary Fig. 1a was due to a non-specific effect of our miR-22 construct, we included the MSCV-PIG-miR-22 construct from Song et al.16 in a repeated CFA. Both miR-22 constructs dramatically inhibited MLL-AF9-induced colony formation (Fig. 1c). As the ‘seed’ sequences at the 5′ end of individual miRNAs are essential for the miRNA-target binding18, we also mutated the 6-bases ‘seed’ sequence of miR-22 and found that the miR-22 mutant did not inhibit colony formation anymore (Fig. 1c). In human AML cells, forced expression of miR-22, but not miR-22 mutant, significantly inhibited cell viability and growth/proliferation, while promoting apoptosis (Supplementary Fig. 1c,d).

Furthermore, as miR-22 is globally downregulated in all major types of AML (Fig. 1b), we also investigated the role of miR-22 in colony formation induced by other oncogenic fusion genes, including MLL-AF10/t(10;11), PML-RARA/t(15;17) and AML1-ETO9a/t(8;21) (ref. 19). As expected, forced expression of miR-22 significantly inhibited colony formation induced by all individual oncogenic fusions; conversely, miR-22 knockout20 significantly enhanced colony forming (Fig. 1d). These results suggest that miR-22 likely plays a broad anti-tumour role in AML.

In accordance with the potential anti-tumour function of miR-22 in AML, miR-22 was expressed at a significantly higher level (P<0.05) in human normal CD33+ myeloid progenitor cells than in more immature CD34+ HSPCs or MNC cells (a mixed population containing both primitive progenitors and committed cells) (Fig. 1a,b), implying that miR-22 is upregulated during normal myelopoiesis. Similarly, we showed that miR-22 was also expressed at a significantly higher level in mouse normal bone marrow (BM) myeloid (Gr-1+/Mac-1+) cells, relative to lineage negative (Lin−) progenitor cells, long-term hematopoietic stem cells (LT-HSCs), short-term HSCs (ST-HSCs), and committed progenitors (CPs) (Supplementary Fig. 1e), further suggesting that miR-22 is upregulated in normal myelopoiesis.

The anti-tumour effect of miR-22 in the pathogenesis of AML

Through bone marrow transplantation (BMT) assays, we showed that forced expression of miR-22 (but not miR-22 mutant) dramatically blocked MLL-AF9 (MA9)-mediated leukemogenesis in primary BMT recipient mice, with a more potent inhibitory effect than miR-150 (Fig. 1e;Supplementary Fig. 2a). All MA9+miR-22 mice exhibited normal morphologies in peripheral blood (PB), BM, spleen and liver tissues (Fig. 1f), with a substantially reduced c-Kit+ blast cell population in BM (Supplementary Fig. 2b). Forced expression of miR-22 also almost completely inhibited leukemogenesis induced by MLL-AF10 (Fig. 1g; Supplementary Fig. 2a). Conversely, miR-22 knockout significantly promoted AML1-ETO9a (AE9a)-induced AML (Fig. 1h). Thus, the repression of miR-22 is critical for the development of primary AML. Notably, forced expression of miR-22 inMLL-AF9 and MLL-AF10 leukaemia mouse models caused only a 2–3-fold increase in miR-22 expression level (Supplementary Fig. 2a), in a degree comparable to the difference in miR-22 expression levels between human AML samples and normal controls (Fig. 1a), suggesting that a 2–3-fold change in miR-22 expression level appears to be able to exert significant physiological or pathological effects.

To examine whether the maintenance of AML is also dependent on the repression of miR-22, we performed secondary BMT assays. Forced expression of miR-22 remarkably inhibited progression of MLL-AF9-, AE9a– or FLT3-ITD/NPM1c+-induced AML in secondary recipient mice (Fig. 2a–d), resulting in largely normal morphologies in PB, BM, spleen and liver tissues (Fig. 2b;Supplementary Fig. 2c). Collectively, our findings demonstrate that miR-22 is a pivotal anti-tumour gatekeeper in both development and maintenance of various AML.

Figure 2: Effect of miR-22 on the maintenance of AML in vivo.

Effect of miR-22 on the maintenance of AML in vivo.

(a,b) Effect of miR-22 on the maintenance of MLL-AF9-induced AML in secondary BMT recipient mice. The secondary BMT recipients were transplanted with BM blast cells from the primary MLL-AF9 AML mice retrovirally transduced with MSCV-PIG+MSCVneo (MA9-AML+Ctrl; n=7) or MSCV-PIG+MSCVneo-miR-22 (MA9-AML+miR-22; n=10). Kaplan–Meier curves (a) and Wright–Giemsa or H&E-stained PB, BM, spleen and liver (b) of the secondary leukaemic mice are shown. (c,d) Effect of miR-22 on the maintenance/progression of AML1-ETO9a (AE9a)-induced AML (c) or FLT3-ITD/NPM1c+-induced AML (d) in secondary BMT recipient mice (n=5 for each group). Kaplan–Meier curves and P values (log-rank test) are shown.

 

Identification of critical target genes of miR-22 in AML

To identify potential targets of miR-22 in AML, we performed a series of data analysis. Analysis of In-house_81S (ref. 21) and TCGA_177S (ref. 22) data sets revealed a total of 999 genes exhibiting significant inverse correlations with miR-22 in expression. Of them, 137 genes, including 21 potential targets of miR-22 as predicted by TargetScan18 (Supplementary Table 1), were significantly upregulated in both human and mouse AML compared with normal controls as detected in two additional in-house data sets14, 23. Among the 21 potential targets, CRTC1, ETV6and FLT3 are known oncogenes24, 25, 26, 27, 28, 29. We then focused on these three genes, along with MYCBP that encodes the MYC-binding protein and is an experimentally validated target of miR-22 (ref. 30) although due to a technical issue it was not shown in the 21-gene list (Supplementary Table 1), for further studies.

As expected, all four genes were significantly downregulated in expression by ectopic expression of miR-22 in human MONOMAC-6/t(9;11) cells (Fig. 3a). The coincidence of downregulation of those genes and upregulation of miR-22 was also observed in mouse MLL-ENL-ERtm cells, a leukaemic cell line with an inducible MLL-ENL derivative31, when MLL-ENL was depleted by 4-hydroxy-tamoxifen (4-OHT) withdrawal (Fig. 3b; Supplementary Fig. 3a). While MLL-AF9 remarkably promoted expression of those four genes in mouse BM progenitor cells, co-expressed miR-22 reversed the upregulation (Fig. 3c). In leukaemia BM blast cells of mice with MLL-AF9-induced AML, the expression of Crtc1, Flt3 and Mycbp, but not Etv6, was significantly downregulated by co-expressed miR-22 (but not by miR-22 mutant) (Fig. 3d). Because miR-22-mediated downregulation of Etv6 could be observed only in the in vitro models (Fig. 3a–c), but not in the in vivo model (Fig. 3d), which was probably due to the difference between in vitro and in vivo microenvironments, we decided to focus on the three target genes (that is, Crtc1, Flt3 and Mycbp) that showed consistent patterns between in vitro and in vivo for further studies. The repression of Crtc1, Flt3 and Mycbpwas also found in leukaemia BM cells of mice with AE9a or FLT3-ITD/NPM1c+-induced AML (Fig. 3e,f). As Mycbp is already a known target of miR-22 (ref. 30), here we further confirmed that FLT3and CRTC1 are also direct targets of miR-22 (Fig. 3g,h). The downregulation of CRTC1, FLT3 and MYCBP by miR-22 at the protein level was confirmed in both human and mouse leukaemic cells (Supplementary Fig. 3b,c). Overexpression of miR-22 had no significant influence on the level of leukaemia fusion genes (Supplementary Fig. 3d).

Figure 3: miR-22 targets multiple oncogenes.

miR-22 targets multiple oncogenes.

(a) Downregulation of CRTC1, FLT3, MYCBP and ETV6 by forced expression of miR-22 in MONOMAC-6 cells. Expression of these genes was detected 48 h post transfection of MSCV-PIG (Ctrl) or MSCV-PIG-miR-22 (miR-22). (b) Crtc1, Flt3, Mycbp and Etv6 levels in MLL-ENL-ERtm cells after withdrawal of 4-OHT for 0, 7 or 10 days. (c) Expression levels of Crtc1, Flt3, Mycbp and Etv6 in mouse BM progenitor cells retrovirally transduced with MSCV-PIG+MSCV-neo (Ctrl), MSCV-PIG-miR-22+MSCV-neo (miR-22), MSCV-PIG+MSCV-neo-MLL-AF9 (MLL-AF9) or MSCV-PIG-miR-22+MSCV-neo-MLL-AF9 (MLL-AF9+miR-22). (d) Expression levels of Crtc1, Flt3, Mycbp and Etv6 in BM blast cells of leukaemic mice transplanted with MLL-AF9, MLL-AF9+miR-22 or MLL-AF9+miR-22mut primary leukaemic cells. (e,f) Expression levels of Crtc1, Flt3 and Mycbp in BM blast cells of leukaemic mice transplanted with MSCV-PIG or MSCV-PIG-miR-22-retrovirally transduced AE9a (e) or FLT3-ITD/NPM1c+ (f) primary leukaemic cells. (g) Putative miR-22 target sites and mutants in the 3′UTRs of CRTC1 (upper panel) and FLT3(lower panel). (h) Effects of miR-22 on luciferase activity of the reporter gene bearing wild type or mutant 3′UTRs of CRTC1 or FLT3 in HEK293T cells. The mean±s.d. values from three replicates are shown.*P<0.05, t-test.

Co-expression of the coding region (CDS) of each of the three target genes (that is, CRTC1, FLT3and MYCBP) largely reversed the effects of miR-22 on cell viability, apoptosis and proliferation (Fig. 4a–e). More importantly, in vivo BMT assays showed that co-expressing CRTC1, FLT3 orMYCBP largely rescued the inhibitory effect of miR-22 on leukemogenesis (Fig. 4f,g;Supplementary Fig. 3e). Our data thus suggest that CRTC1, FLT3 and MYCBP are functionally important targets of miR-22 in AML.

Figure 4: Multiple onocgenes are functionally important targets of miR-22 in AML.

Multiple onocgenes are functionally important targets of miR-22 in AML.

(a,b) Relative viability (a) and apoptosis (b) levels of MONOMAC-6 cells transfected with MSCV-PIG-CRTC1, -FLT3 or –MYCBP alone, or together with MSCVneo-miR-22. Values were detected 48 h post transfection. (c–e) Rescue effects of CRTC1 (c), FLT3 (d) and MYCBP (e) on the inhibition of MONOMAC-6 growth mediated by miR-22. Cell counts at the indicated time points are shown. Mean±s.d. values are shown. *P<0.05, t-test. (f) In vivo rescue effects of CRTC1, FLT3 and MYCBP on the inhibition of MLL-AF9-induced leukemogenesis mediated by miR-22. The secondary recipients were transplanted with BM blast cells of the primary MLL-AF9 leukaemic mice retrovirally transduced with MSCVneo+MSCV-PIG (MA9-AML+Ctrl; n=7), MSCVneo-miR-22+MSCV-PIG (MA9-AML+miR-22; n=10), MSCVneo-miR-22+MSCV-PIG-CRTC1 (MA9-AML+miR-22+CRTC1; n=5), MSCVneo-miR-22+MSCV-PIG-FLT3 (MA9-AML+miR-22+FLT3; n=6) or MSCVneo-miR-22+MSCV-PIG-MYCBP (MA9-AML+miR-22+MYCBP; n=6). Kaplan–Meier curves for all the five groups of transplanted mice are shown. MA9-AML+Ctrl versus MA9-AML+miR-22, P<0.001 (log-rank test); MA9-AML+Ctrl versus any other groups,P>0.05 (log-rank test). (g) Wright–Giemsa stained PB and BM, and H&E stained spleen and liver of the secondary leukaemic mice.

miR-22 represses both CREB and MYC signalling pathways

DNA copy-number loss of miR-22 gene locus in AML

Expression of miR-22 is epigenetically repressed in AML

 

Figure 5: Transcriptional correlation between miR-22 and TET1.

http://www.nature.com/ncomms/2016/160426/ncomms11452/images_article/ncomms11452-f5.jpg

(a) Correlation between the expression levels of miR-22 and TET1 in three independent AML patient databases. All expression data were log(2) transformed; the data in In-house_81S were also mean-centred. The correlation coefficient (r) and P values were detected by ‘Pearson Correlation’, and the correlation regression lines were drawn with the ‘linear regression’ algorithm. (b) Expression of pri-, pre- and mature miR-22, and Tet1/2/3 in colony-forming cells of wild-type mouse BM progenitors retrovirally transduced with MSCVneo (Ctrl), MSCVneo-MLL-AF9 (MLL-AF9), MSCVneo-MLL-AF10 (MLL-AF10) or MSCVneo-AE9a (AE9a), or of FLT3-ITD/NPM1c+ mouse BM progenitors transduced with MSCVneo (FLT3-ITD+/NPM1c+). (c) Expression of miR-22 and Tet1/2/3 in MLL-ENL-ERtm cells. Expression levels were detected at the indicated time points post 4-OHT withdrawal. (d) Effect of miR-22 overexpression onTet1 expression in colony-forming cells with MLL-AF9, AE9a or FLT3-ITD/NPM1c+. (e) Expression ofTet1 in BM progenitor cells of 6-weeks old miR-22−/− or wild-type mice. (f) Effect of miR-22 overexpression on TET1 expression in THP-1 and KOCL-48 AML cells 48 h post transfection. (g) Expression of pri-, pre- and mature miR-22 in BM progenitor cells of 6-weeks old Tet1−/− or wild-type mice. Mean±s.d. values are shown. *P<0.05, t-test.

http://www.nature.com/ncomms/2016/160426/ncomms11452/images_article/ncomms11452-f6.jpg

(a) Tet1 targets miR-22 promoter region (−1,100/+55 bp), as detected by luciferase reporter assay 48 h post transfection in HEK293T cells. (b) Expression of TET1/2/3, EZH2, SIN3A, GFI1 and miR-22 in THP-1 cells 72 h post treatment with 1 μM ATRA or DMSO control. (c) Co-immunoprecipitation assay showing the binding of endogenous GFI1 and TET1 in THP1 cells. (d) ChIP-qPCR analyses of the promoter region of miR-22 in THP-1 cells 72 h post treatment with 1 μM ATRA or DMSO. Upper panel: PCR site on the CpG-enriched region of miR-22 gene locus. Note: miR-22 is coded within the second exon of a long non-coding RNA (MIR22HG), which represents the primary transcript of miR-22. Lower panels: enrichment of MLL-N terminal (for both wild-type MLL and MLL-fusion proteins), MLL-C terminal (for wild-type MLL), TET1, EZH2, SIN3A, GFI1, H3K27me3, H3K4me3 or RNA pol II at miR-22 promoter region. (e) Expression levels of TET1, EZH2, SIN3A and miR-22 in GFI1 knockdown cells. (f) ChIP-qPCR analyses of the promoter region of miR-22 in THP-1 cells transduced with GFI1 shRNA or control shRNA. Enrichment of GFI1, TET1, EZH2 and SIN3A are shown. (g) Effects of knockdown of TET1, EZH2 and/orSIN3A on miR-22 expression. The expression level of miR-22 was detected in THP-1 cells 72 h post transfection with siRNAs targeting TET1, EZH2 and/or SIN3A. Mean±s.d. values are shown. *P<0.05;**P<0.01 (t-test). (h) Schematic model of the regulatory pathway involving miR-22 in AML and ATRA treatment.

 

The miR-22-associated regulatory circuit in AML

         Restoration of miR-22 expression and function to treat AML

 

Figure 7: Therapeutic effect of miR-22-nanoparticles in treating AML.

http://www.nature.com/ncomms/2016/160426/ncomms11452/images_article/ncomms11452-f7.jpg

(a,b) Primary leukaemia BM cells bearing MLL-AF9 (a) or AE9a (b) were transplanted into sublethally irradiated secondary recipient mice. After the onset of secondary AML (usually 10 days post transplantation), the recipient mice were treated with PBS control, or 0.5 mg kg−1 miR-22 or miR-22 mutant RNA oligos formulated with G7 PAMAM dendrimer nanoparticles, i.v., every other day, until the PBS-treated control group all died of leukaemia. (c) NSGS mice49 were transplanted with MV4;11/t(4;11) AML cells. Five days post transplantation, these mice started to be treated with PBS control, miR-22 or miR-22 mutant nanoparticles at the same dose as described above. Kaplan–Meier curves are shown; the drug administration period and frequency were indicated with yellow arrows. The P values were detected by log-rank test. (d) Wright–Giemsa stained PB and BM, and H&E stained spleen and liver of the MLL-AF9-secondary leukaemic mice treated with PBS control, miR-22 or miR-22 mutant nanoparticles.

We then tested the miR-22 nanoparticles in a xeno-transplantation model49. Similarly, the nanoparticles carrying miR-22 oligos, but not miR-22 mutant, significantly delayed AML progression induced by human MV4;11/t(4;11) cells (Fig. 7c). The miR-22-nanoparticle administration also resulted in less aggressive leukaemic pathological phenotypes in the recipient mice (Supplementary Fig. 6e). Thus, our studies demonstrated the therapeutic potential of using miR-22-based nanoparticles to treat AML.

 

It remains poorly understood how TET proteins mediate gene regulation in cancer. Here we show that in de novo AML, it is TET1, but not TET2 (a reported direct target of miR-22 in MDS and breast cancer15, 16), that inversely correlates with miR-22 in expression and negatively regulates miR-22 at the transcriptional level. Likely together with GFI1, TET1 recruits polycomb cofactors (for example, EZH2/SIN3A) to the miR-22 promoter, leading to a significant increase in H3K27me3 occupancy and decrease in RNA pol II occupancy at that region, and thereby resulting in miR-22 repression in AML cells; such a repression can be abrogated by ATRA treatment. Thus, our study uncovers a novel epigenetic regulation mechanism in leukaemia involving the cooperation between TET1/GFI1 and polycomb factors.

Besides GFI1, it was reported that LSD1 is also a binding partner of TET1 (ref. 50). Interestingly, LSD1 is known as a common binding partner shared by TET1 and GFI1, and mediates the effect of GFI1 on hematopoietic differentiation51, 52. Thus, it is possible that LSD1 might also participate in the transcriptional repression of miR-22 as a component of the GFI1/TET1 repression complex.

We previously reported that TET1 cooperates with MLL fusions in positively regulating their oncogenic co-targets in MLL-rearranged AML14. Here we show that TET1 can also function as a transcriptional repressor (of a miRNA) in cancer. The requirement of TET1-mediated regulation on expression of its positive (for example, HOXA/MEIS1/PBX3)14 or negative (for example, miR-22) downstream effectors in leukemogenesis likely explains the rareness of TET1 mutations in AML53, and highlights its potent oncogenic role in leukaemia.

The aberrant activation of both CREB and MYC signalling pathways has been shown in AML24, 25,26, 54, 55, but the underlying molecular mechanisms remain elusive. Our data suggest that the activation of these two signalling pathways in AML can be attributed, at least in part, to the repression of miR-22, which in turn, results in the de-repression of CRTC1 (CREB pathway), FLT3and MYCBP (MYC pathway), and leads to the upregulation of oncogenic downstream targets (for example, CDK6, HOXA7, BMI1, FASN and HMGA1) and downregulation of tumour-suppressor downstream targets (for example, RGS2).

In summary, we uncover a TET1/GFI1/EZH2/SIN3A⊣miR-22⊣CREB-MYC signalling circuit in de novo AML, in which miR-22 functions as a pivotal anti-tumour gate-keeper, distinct from its oncogenic role reported in MDS or MDS-derived AML16. Thus, our study together with the study of Song et al.16 highlight the complexity and functional importance of miR-22-associated gene regulation and signalling pathways in hematopoietic malignancies, and may provide novel insights into the genetic/epigenetic differences between de novo AML and MDS.

Our findings also highlight the possibility of using miR-22-based therapy to treat AML patients. Our proof-of-concept studies demonstrate that the nanoparticles carrying miR-22 oligos significantly inhibit AML progression and prolong survival of leukaemic mice in both BMT and xeno-transplantation models. Notably, miRNA-based nanoparticles have already entered clinical trials56. It would be important, in the future, to further test the combination of miR-22-carrying nanoparticles (or small-molecule compounds that can induce endogenous expression of miR-22) with standard chemotherapy agents (cytosine arabinoside and anthracycline), or with the emerging small molecule inhibitors against MYC and/or CREB pathway effectors, to achieve optimal anti-leukaemia effect with minimal side effects. Overall, our results suggest that restoration of miR-22 expression/function (for example, using miR-22-carrying nanoparticles or small-molecule compounds) holds great therapeutic potential to treat AML, especially those resistant to current therapies.

 

MicroRNAs: A Gene Silencing Mechanism with Therapeutic Implications  

Wed, July 13, 2016   The New York Academy of Sciences    Presented by the Biochemical Pharmacology Discussion Group
http://www.nyas.org/Events/Detail.aspx?cid=787a5d77-8354-4df7-92d5-91db18b2ce49

MicroRNAs (miRNAs) are single-stranded RNAs about 22 nucleotides in length that repress the expression of specific proteins by annealing to complementary sequences in the 3′ untranslated regions (UTRs) of target mRNAs. Apart from their posttranscriptional expression, or silencing, miRNAs may also direct mRNA destabilization and cleavage. Moreover, rather than targeting a single disease-associated protein target as many small molecule drugs and antibodies do, each miRNA may serve to repress the expression of numerous proteins involved in the pathogenesis and progression of various diseases and could therefore potentially interfere with multiple disease-promoting signal transduction pathways. Because aberrant expression of miRNAs has been implicated in numerous disease states, miRNA-based therapies have sparked much interest for the treatment of a variety of diseases. The objective of this symposium is to bring together investigators who have led the field in describing what miRNAs do and their potential in treating diseases, as well as those who are translating these findings into promising drug candidates, some of which have already advanced into early stage clinical trials.

Call for Poster Abstracts

Abstract submissions are invited for a poster session. For complete submission instructions, please send an email to miRNA@nyas.org with the words “Abstract Information” in the subject line. The deadline for abstract submission is May 13, 2016.

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