The mir-301a story: Regulation of mitochondria by microrna

Transcription

1 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

2 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

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4 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

5 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

6 Taken from Schulze and Harris, Nature, 2012

7 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

8 I Hexokinase inhibitors MITOCANS 3-Bromopyruvate, 2-oxoglucose II III IV V BH3 mimetics Thiol redox inhibitors VDAC/ANT targeting drugs Electron transport chain targeting drugs Gossypol, antimycin, a-tocopheryl succinate Isothiocyanates, arsenites Ionidamine, steroid analogues like CD437 a-tocopheryl succinate, MitoVES, 4-OH retinamide, tamoxifen, antimycin, adaphostin, 3-bromopyruvate VI VII Lipophilic cations targeting inner membrane Drugs targeting mtdna Rhodamine-123, Rose Bangal, (KLAKKLAK) 2 peptide Vitamin K 3, fialuridine, 1-methyl-4- phenylpyridinium, MitoVES VIII Drugs targeting other sites Oxidised cardiolipin, betulinic acid, resveratrol

9 MITOCANS D-α-Tocopheryl succinate-tpp O - O O O O + P MitoVES (2)

10 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

11 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

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13 MIR-301A-3P INDUCTION (DOSE RESPONSE) R e l a t i v e p r e - m i R a E x p r e s s i o n c t r l 1 p r e - m i R a R e l a t i v e m i R a - 3 P E x p r e s s i o n C T R L m a t u r e m i R a - 3 P D o x y c y c l i n e ( n g / m l ) D o x y c y c l i n e ( n g / m l )

14 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

15 Mitochondrial biogenesis and regulation ESR1

16 ESR1 (ER ), PPARG (PPAR ) AND PPARGC1(PGC1 ) AS A TARGETS OF MIR-301A

17 EFFECT OF MIR301A ON THE EXPRESSION OF ESR1 AND ITS TARGET GENE TFF1A R e l a t i v e E S R 1 E x p r e s s i o n E S R 1 R e l a t i v e E S R 1 E x p r e s s i o n E S R 1 n o m i R a C T R L C T R L D o x y c y c l i n e ( n g / m l ) D o x y c y c l i n e ( n g / m l ) T F F 1 A n o m i R a R e l a t i v e T F F 1 A E x p r e s s i o n T F F 1 A R e l a t i v e T F F 1 A E x p r e s s i o n C T R L C T R L D o x y c y c l i n e ( n g / m l ) D o x y c y c l i n e ( n g / m l )

18 EFFECT OF MIR-301A ON ER TARGET GENES R e l a t i v e T F F 1 A E x p r e s s i o n T F F 1 A R e l a t i v e G R E B 1 E x p r e s s i o n G R E B 1 A C T R L C T R L D o x y c y c l i n e ( n g / m l ) D o x y c y c l i n e ( n g / m l ) R e l a t i v e P G R E x p r e s s i o n P G R C T R L D o x y c y c l i n e ( n g / m l )

19 EFFECT OF MIR-301A ON GENES REGULATING MITOCHONDRIAL TRANSCRIPTION AND BIOGENESIS R e l a t i v e T F A M E x p r e s s i o n C T R L 1 T F A M R e l a t i v e D - L O O P E x p r e s s i o n 1. 2 D - L O O P C T R L D o x y c y c l i n e ( n g / m l ) D o x y c y c l i n e ( n g / m l ) R e la tiv e P P A R G C 1 E x p re s s io n c tr l 1 P P A R G C D o x y c y c lin e (n g /m l)

20 EFFECT OF MIR-301A ON PROTEIN LEVEL OF IMPORTANT MITOCHONDRIAL REGULATORS ER ERβ 66kDa- 47kDa- 36kDa- 50kDa- DOX (ng/ml) CTRL Actin 45 Kda- DOX (ng/ml) CTRL NRF1 70KDa- NRF2 90KDa- PGC1 50kDa- PPAR 50KDa- TUBULIN 50kDa-

21 EFFECT OF MIRNA-301A ON MITOCHONDRIAL CI AND CII IN GEL CATALYTIC ACTIVITY, HRCNE CI+CIII+CIV- CI+CIII- CI- mir-301a mock DOX DOX DOX CII-

22 LEVELS OF MIR-301A IN TAMOXIFEN RESISTANT (TAMR) MCF7 TAMOXIFEN RESISTANT (TAMR) BREAST CANCER CELLS REPRESENT MAJOR THERAPEUTICAL PROBLEM IN WOMEN TREATED WITH ANTI- ESTROGENE 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.

23 R e la tiv e m ir a E x p re s s io n m a tu r e m ir P M C F 7 M C F 7 -T A M R

24 EFFECT OF MIRNA-301A ON NF B SIGNALLING, LUCIFERASE REPORTER ASSAY N F B A c tiv ity R e la tiv e N F B A c tiv ity c tr l 1 n g /m l D O X 1 0 n g /m l D O X n g /m l D O X n g /m l D O X n g /m l D O X

25 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

26 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

27 ACKNOWLEDGEMENTS LABORATORY OF TUMOUR RESISTANCE LABORATORY OF MOLECULAR THERAPY

28 THANK YOU FOR YOUR ATTENTION

29 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 mir- 301a 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.

30 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

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33 EFFECT OF MIR-301A ON PROTEIN LEVEL OF IMPORTANT MITOCHONDRIAL TRANSCRIPTION FACTOR TFAM mir-301a mock DOX DOX DOX TFAM 25kDa- PONCEAU RED

34 I Hexokinase inhibitors 3-Bromopyruvate, 2-oxoglucose II III BH3 mimetics Thiol redox inhibitors Gossypol, antimycin, a-tocopheryl succinate Isothiocyanates, arsenites IV V VDAC/ANT targeting drugs Electron transport chain targeting drugs Ionidamine, steroid analogues like CD437 a-tocopheryl succinate, MitoVES, 4-OH retinamide, tamoxifen, antimycin, adaphostin, 3-bromopyruvate VI VII Lipophilic cations targeting inner membrane Drugs targeting mtdna Rhodamine-123, Rose Bangal, (KLAKKLAK) 2 peptide Vitamin K 3, fialuridine, 1-methyl-4- phenylpyridinium, MitoVES VIII Drugs targeting other sites Oxidised cardiolipin, betulinic acid, resveratrol