The miR-301a story: Regulation of mitochondria by microRNA INSTITUTE OF BIOTECHNOLOGY, ASCR, LABORATORY OF TUMOUR RESISTANCE SANDRA LETTLOVÁ, ZUZANA RYCHTARČÍKOVÁ, VERONIKA TOMKOVÁ, MAGDALENA VONDRUSOVÁ, JAROSLAV TRUKSA INTRODUCTION TO MICRORNA • Small non-coding RNAs which are normally transcribed by RNA pol II • After processing from primary miRNA (pri-miR) to precursor miRNA (premiR) by Drosha it is further cleaved by DICER to gain fully mature miRNA • Mature miRNA binds to the target mRNA sequence via its 7-10 nt long „seed sequence“ and affects negatively the expression of the target gene via RNA-induced silencing complex (RISC) • Molecular mechanisms behind this are either mRNA cleavage or translational repression • miRNA can bind to promoter sequences, CDS as well as 5’ and 3’ UTR • Mode of action of microRNA is multifaceted, e.g. one microRNA can target hundreds of unrelated targets MITOCHONDRIA AND MIRNA • Regulation of mitochondrial function and biogenesis by microRNA is not well understood at present • Several miRNAs targeting key components of mitochondrial function and biogenesis have been identified (miR-126, miR-210, miR-30 family) • We believe that many oncomiRs and miRs acting as tumour suppressors also affect mitochondrial function since modulation of mitochondrial function seems to be an important step in carcinogenesis MITOCHONDRIA AND CANCER • Cancer cells are usually believed to depend mainly on glycolysis. However, they need their mitochondria to provide supply of metabolites and intermediates required for rapid proliferation • Mitochondria are also critical regulators of cell death as they are essential components of the cellular machinery that controls apoptosis induction • Targeting cancer mitochondria is a novel way that could help overcome the extreme plasticity and ability to mutate in cancer cells. Compounds that target cancer mitochondria have been termed MITOCANs Taken from Schulze and Harris, Nature, 2012 MITOCANS • Mitocans are compounds that target mitochondria of cancer cells and induce their destabilization and induce apoptosis • At present there are 8 classess of mitocans • One of the promising mitocan that targets mitochondrial complexII is the mitochonndrially targeted derivative of vitamin E succinate, mitoVES • MitoVES concentrates in the mitochondria, induces generation of reactive oxygen species and inhibits mitochondrial respiration and biogenesis MITOCANS I Hexokinase inhibitors 3-Bromopyruvate, 2-oxoglucose II BH3 mimetics Gossypol, antimycin, a-Tocopheryl succinate III Thiol redox inhibitors Isothiocyanates, arsenites IV VDAC/ANT targeting drugs Ionidamine, steroid analogues like CD437 V Electron transport chain targeting drugs a-Tocopheryl succinate, MitoVES , 4-OH retinamide, tamoxifen, antimycin, adaphostin, 3-bromopyruvate VI Lipophilic cations targeting inner membrane Rhodamine-123, Rose Bangal, (KLAKKLAK)2 peptide VII Drugs targeting mtDNA Vitamin K3, fialuridine , 1-methyl-4phenylpyridinium , MitoVES VIII Drugs targeting other sites Oxidised cardiolipin, betulinic acid, resveratrol MITOCANS D-α-Tocopheryl succinate-TPP O O O + P O O MitoVES (2) THE MIRNA SCREEN USING MITOVES • We have treated MCF7 breast cancer cells with mitochondrially targeted vitamin E analogue, MitoVES, a compound that inhibits the mitochondrial function and biogenesis and analysed the miRNA profile of the control and MitoVES treated cells • One of the candidate miRNAs that are highly downregulated after MitoVES treatment was mi-RNA301a MIR-301A IN LITERATURE • High expression of mir-301a increases metastatic potential of breast cancer via Wnt/β-catenin activation and PTEN targeting • High expression of mir-301a in gastric cancer promotes proliferation and invasion, mechanisms is via RUNX3 targeting • Mir-301a is a positive regulator of NFB signalling via inhibiting the NF B repressing factor (NKRF) in pancreatic cell lines and it also promotes their proliferation by directly targeting BIM • Link between mitochondria and mir-301a has not been defined yet Taken from Ma et al., Gene, 2014 5 4 3 2 0 0 1 C D o x y c y c lin e ( n g /m l) 0 0 0 5 0 T 1 0 0 1 1 0 6 1 0 0 0 0 5 0 1 0 0 1 1 tr l 0 7 1 10 8 20 9 L 30 m a tu r e m iR -3 0 1 a -3 P R 40 R e la tiv e m iR 3 0 1 a -3 P E x p r e s s io n p r e -m iR 3 0 1 a c R e la t iv e p r e - m iR - 3 0 1 a E x p r e s s io n MIR-301A-3P INDUCTION (DOSE RESPONSE) D o x y c y c lin e ( n g /m l) MIR301A TARGETS RELATED TO MITOCHONDRIA • MiRNA-301a has several thousands of predicted targets, some of which are related to mitochondria such as ER, PGC1 and PPAR • Primers were generated and expression of selected targets assessed by qPCR • Some of the important regulators of mitochondrial function and biogenesis were also assessed on the protein level Adapted from Boland et al., Front. Oncol., 2013 Mitochondrial biogenesis and regulation ESR1 ESR1 (ER), PPARG (PPAR) AND PPARGC1(PGC1) AS A TARGETS OF MIR-301A 0 0 0 0 1 1 C 1 C 0 T 5 L R 0 0 0 5 0 0 1 0 0 1 1 L R T 0 0 .5 0 0 .5 0 0 .7 5 0 0 .7 5 1 .0 0 0 1 .0 0 1 .2 5 0 1 .2 5 E S R 1 n o m iR 3 0 1 a 1 .5 0 1 E S R 1 1 .5 0 1 R e la tiv e E S R 1 E x p r e s s io n R e la tiv e E S R 1 E x p r e s s io n EFFECT OF MIR301A ON THE EXPRESSION OF ESR1 AND ITS TARGET GENE TFF1A D o x y c y c lin e ( n g /m l) C 0 1 0 0 0 0 5 0 T R 0 1 0 L 0 0 .5 0 0 0 0 5 0 1 0 0 1 1 T R L 0 .4 0 .7 5 1 0 .6 1 .0 0 0 0 .8 1 .2 5 1 1 .0 1 .5 0 1 R e la tiv e T F F 1 A E x p r e s s io n T F F 1 A n o m iR 3 0 1 a T F F 1A 1 .2 C R e la tiv e T F F 1 A E x p r e s s io n D o x y c y c lin e ( n g /m l) D o x y c y c lin e ( n g /m l) D o x y c y c lin e ( n g /m l) 0 .4 0 .8 0 .6 0 .4 0 1 0 0 0 0 5 0 1 0 0 1 1 T R L 0 .2 D o x y c y c lin e ( n g /m l) 0 0 1 C 1 .0 0 0 0 5 R T 0 1 0 L 0 0 0 5 0 0 1 0 0 1 1 L R T C D o x y c y c lin e ( n g /m l) P G R C E x p r e s s io n D o x y c y c lin e ( n g /m l) R e la tiv e P G R 0 0 .2 0 .4 0 .6 1 0 .6 0 .8 0 0 .8 1 .0 1 1 .0 G R E B 1A 1 E x p r e s s io n T F F 1A 1 .2 R e la tiv e G R E B 1 R e la tiv e T F F 1 A E x p r e s s io n EFFECT OF MIR-301A ON ER TARGET GENES D o x y c y c lin e ( n g /m l) PPARGC1 1 .2 5 1 .0 0 0 .7 5 0 1 0 0 0 0 5 0 0 0 1 1 1 c tr l 0 .5 0 D o x y c y c lin e ( n g /m l) 0 0 0 0 0 C 1 1 T 5 R 0 L 0 0 0 .2 0 5 C D o x y c y c lin e ( n g /m l) R e la tiv e P P A R G C 1 E x p r e s s io n 0 .4 0 0 0 0 0 T 1 R 1 1 L 0 0 .2 0 .6 1 0 .4 0 .8 0 0 .6 1 R e la tiv e D - L O O P 0 .8 1 .0 1 1 .0 D -L O O P 1 .2 E x p r e s s io n T F A M R e la tiv e T F A M E x p r e s s io n EFFECT OF MIR-301A ON GENES REGULATING MITOCHONDRIAL TRANSCRIPTION AND BIOGENESIS EFFECT OF MIR-301A ON PROTEIN LEVEL OF IMPORTANT MITOCHONDRIAL REGULATORS DOX (ng/ml) DOX (ng/ml) CTRL ER 66kDa47kDa- 36kDa- ERβ 50kDa- PGC1 50kDaPPAR 50KDa- TUBULIN 50kDa- 1 10 100 500 1000 CTRL NRF1 70KDaNRF2 90KDa- Actin 45 Kda- 1 10 100 500 1000 EFFECT OF MIRNA-301A ON MITOCHONDRIAL CI AND CII „IN GEL“CATALYTIC ACTIVITY, HRCNE miR-301a DOX DOX + + CI+CIII+CIVCI+CIIICI- CII- mock DOX + LEVELS OF MIR-301A IN TAMOXIFEN RESISTANT (TAMR) MCF7 • TAMOXIFEN RESISTANT (TAMR) BREAST CANCER CELLS REPRESENT MAJOR THERAPEUTICAL PROBLEM IN WOMEN TREATED WITH ANTIESTROGENE DRUG TAMOXIFEN • THESE CELLS GROW INDEPENDENTLY OF ESTROGENE AND ACTIVATE PRO-SURVIVAL SIGNALS SUCH AS NFB • THE LEVELS OF MIR-301A IN THESE CELLS IS SIGNIFICANTLY UPREGULATED AND MIGHT BE A FACTOR CONTRIBUTING TO THEIR RESISTANCE. M C F 7 -T F M C A M R 7 R e la t iv e m iR -3 0 1 a E x p r e s s io n 2 .5 m a t u r e m iR 3 0 1 - 3 P 2 .0 1 .5 1 .0 EFFECT OF MIRNA-301A ON NF B SIGNALLING, LUCIFERASE REPORTER ASSAY N F  B A c tiv ity 1 .5 0 1 .2 5 1 .0 0 0 0 1 5 0 0 X O 0 n n g g /m /m l l D D O O D l /m g n 0 0 1 X X X O D n 0 1 n g g /m /m l l D c O tr X l 0 .7 5 1 R e la t iv e N F  B A c t iv ity 1 .7 5 SUMMARY • Our results support the role of mir-301a as an „oncomir“ and we suppose that prooncogenic properties of miR-301a are at least partially connected to its ability to modulate mitochodrial function and biogenesis and inhibit ER signalling • MiR-301a inhibits mitochondrial biogenesis and function via inhibition of the ER and PGC1 signaling resulting in lower levels of NRF2. Higher levels of miR-301a also seems to be connected with the activation of NF B signaling • Reduced mitochondrial function, insensitivity to ER modulating drugs and NF B activation are typical for the hormone resistant cancers and miR-301a thus could be a contributing factor that promotes the transformation to a harder to treat tumours with aggressive phenotype TAKE HOME MESSAGE MitoVES ER miR-301a PGC1 NFB NFR2 Transcription of core mitochondrial proteins (TFAM, TOP1MT,DNApol) Transcription of components of mitochondria coded inside mitochondria Transcription of nuclearly coded mitochondrial proteins Function of the ETC chain ACKNOWLEDGEMENTS • LABORATORY OF TUMOUR RESISTANCE • LABORATORY OF MOLECULAR THERAPY THANK YOU FOR YOUR ATTENTION FUTURE DIRECTIONS • Define the expression of NRF1 and NRF2, important mitochondrial regulators and targets for ER and PGC1 • Confirm the functionality of miR-301a seed sequences in the ESR1 and PPARGC1 mRNA by directed mutagenesis and luciferase reporter assays • Define the effect of mir-301a on mitochondrial ultrastructure as miR301a is predicted to target OPA-1, a protein critical for the arrangement and normal function of mitochondrial cristae • Assess the effect of miR-301a on mitochondrial respiration by using oxygraph measurements and assess activity of additional ETC complexes • Define the effect of mIR-301a on autophagy as there are predicted MIR-301A targets that play crucial role in autophagy (ATG7) • Perform in vivo experiments and test the role of miR301a in TAMR breast cancer cells. GENERATING THE MIRNA-301A INDUCIBLE SYSTEM • We have generated the miRNA-301a inducible system by employing a two component TETON-3G system from Clontech • The system is composed of two plasmids, one coding for the transactivation protein that, in cooperation with doxycycline, turns on the expression plasmid containing the pri-miR-301a EFFECT OF MIR-301A ON PROTEIN LEVEL OF IMPORTANT MITOCHONDRIAL TRANSCRIPTION FACTOR TFAM miR-301a DOX DOX + + TFAM 25kDa- PONCEAU RED mock DOX + I Hexokinase inhibitors 3-Bromopyruvate, 2-oxoglucose II BH3 mimetics Gossypol, antimycin, a-Tocopheryl succinate III Thiol redox inhibitors Isothiocyanates, arsenites IV VDAC/ANT targeting drugs Ionidamine, steroid analogues like CD437 V Electron transport chain targeting drugs a-Tocopheryl succinate, MitoVES , 4-OH retinamide, tamoxifen, antimycin, adaphostin, 3-bromopyruvate VI Lipophilic cations targeting inner membrane Rhodamine-123, Rose Bangal, (KLAKKLAK)2 peptide VII Drugs targeting mtDNA Vitamin K3, fialuridine , 1-methyl-4phenylpyridinium , MitoVES VIII Drugs targeting other sites Oxidised cardiolipin, betulinic acid, resveratrol