Mitochondrial electron transport chain as a target for anti-cancer drugs

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1 Mitochondrial electron transport chain as a target for anti-cancer drugs Jakub Rohlena Laboratory of Molecular Therapy, Institute of Biotechnology, Academy of Sciences of the Czech Republic, Prague, Czech Republic

2 Challenges for cancer therapy Genetic variability of cancer Similarity between tumour and normal tissue difficult to discriminate Complexity of tumour environment angiogenesis, interaction with stroma cells, immune system etc. Hierarchy of cells within the tumour tumour initiating cells etc.

3 Genetic heterogeneity of tumours

4 Common phenotypic manifestation Warbug s effect upregulation of aerobic glycolysis van der Heiden et al, Science 2009

5 Glycolysis and oxidative phosphorylation is directed by oncogenes and tumour supressors van der Heiden et al, Science 2009

6 Tricarboxylic acid (Krebs) cycle (TCA) Wallace et al, Nat Rev Cancer 2012

7 Mitochondrial electron transport chain (ETC) Intermembrane space e - e - Mitochondrial inner membrane succinate fumarate Matrix

8 Mitochondrial membrane potential ETC and mitochondrial membrane potential H H H H H H H H H H H H H H H H H H Intermembrane space Mitochondrial inner membrane succinate fumarate Matrix H H H

9 Cancer cells susceptible to the inhibition of ETC?

10 Vitamin E analogues HO - OCOCH 2 CH 2 COO O O -TOH -Tocopherol -TOS -Tocopheryl succinate

11 a-tocopheryl succinate induces apoptosis Transition electron microscopy reveals morphological changes, showing gradual apoptotic features, in Jurkat T-lymphoma cells (A, B), treated with α-tos for 6 (C, D), 12 (E, F), and 24 h (G, H). Weber et al (2003) Biochemistry 42,

12 Vitamin E analogues and mitochondrial targeting X P X P X P X P - - X - - P - - P X

13 mitoves is quickly taken up by mitochondria and reduces mitochondrial membrane potential

14 % cells with high MMP Mitochondrial targeting enhances oxidative stress induction α-tos mitoves % cells with high ox stress

15 Anticancer activity of vitamin E analogues

16 Apoptosis (%) Specificity for cancer cells Jurkat HCT-116 MCF7 50 M 10 M 5 M 2 M 1 M MDA-MB-453 Non Meso-2 transformed cells AE17 Non-transformed cells M MitoVES A Met-5A H9c Time (h) Time (h)

17 Apoptosis (%) Apoptosis (%) Mitochondrial complex II deficient cells are resistant to αtos and mitoves α-tos mitoves WT CI deficient CII deficient CII reconstituted * Control MVES, 12 h MVES, 24 h 0 Ctrl αtos 100 µm 0 wt CII-deficient CIIreconstituted

18 Modeling of interaction with Complex II α-tos MitoVES

19 Mitochondrial respiratory complex II SDHA SDHB SDHC SDHD Sun et al (2005) Crystal structure of mitochondrial respiratory membrane protein complex. Cell 121,

20 SDHC mutagenesis in SDHC-deficient hamster lung fibroblast cells (B9) I56 R72 I56 S68 I69 R72 F,K,V A, L E C S68 I69E I69 S68 - wt I56F S68L S68A I69E R72C I56K I56V I69 I56 CII R72 VDAC2

21 SQR activity (relative to wt- SDHC) Mutations in SDHC affect the activity of Complex II Succinyl coenzym Q oxydoreductase (SQR) activity I56 Q QH 2 e - SDHC SDHD SDHB Mitochondrial inner membrane I69 S68 R72 Fumarate SDHA Succinate * * TCA CYCLE * SDHC - I56K I56V I56F S68A S68L R72C I69E SDHC variant * * * *

22 Apoptosis (% positive) Mutations in SDHC diminish α-tos induced apoptosis ROS I56 TOS Apoptosis Q QH 2 I69 S68 R72 e - SDHD SDHC SDHB Mitochondrial inner membrane SDHA 50 ctrl 40 TOS 100 µm Fumarate Succinate WT - S68L I56F SDHC variant

23 Relative tumour volume Relative tumour volume Mutations in SDHC diminish α-tos effectiveness in vivo in a xenograft tumour model wt ctrl wt TOS I * * * * * Time (days) I69 S68 R I56F ctrl I56F TOS Time (days)

24 Mutations in SDHC diminish mitoves induced apoptosis ROS I56 mitoves Apoptosis Q QH 2 I69 S68 R72 e - SDHD SDHC SDHB Mitochondrial inner membrane SDHA Fumarate Succinate

25 Mutations in SDHC diminish inhibition of respiration by mitoves I56 I69 S68 R72 succinate

26 Conclusions Mitochondrial electron transport chain is a promising area for development of new cancer therapeutics with potential broad applicability Data indicate that the ubiquinone binding sites of mitochondrial complex II is a bona fide target site for vitamin E analogues. Delivery of electron transport chain-directed compounds into mitochondria greatly increases their anticancer activity without compromising specificity..

27 Acknowledgements Katarina Kuckova, Jiri Cerny, Jiri Neuzil Institute of Biotechnology, Academy of Sciences of the Czech Republic, Prague, Czech Republic Lanfeng Dong, Jiri Neuzil Griffith University, Gold Coast, Queensland, Australia Jan Stursa UOCHB, Academy of Sciences of the Czech Republic, Prague, Czech Republic Victoria Adlam, Robin Smith Otago University, Dunedin, New Zealand

28 The decrease in mitochondrial membrane potential by mitoves enhances respiration

29 Higher ETC flow upon mitoves treatment Intermembrane space e - e - Mitochondrial inner membrane succinate fumarate Matrix

What is the primary location of mitochondrial respiratory complexes? These complexes are embedded in the inner mitochondrial membrane.

Interactive Questions Question 1: What is the primary location of mitochondrial respiratory complexes? Outer mitochondrial membrane Mitochondrial inter-membrane space Inner mitochondrial membrane These