Abstract
Apoptotic elimination of UV-damaged cells from the epidermis is an important step in preventing both the emergence and expansion of cells with carcinogenic potential. A pivotal event in apoptosis is the release of apoptogenic factors from the mitochondria, although the mechanisms by which the different proteins are released are not fully understood. Here we demonstrate that UV radiation induced the mitochondrial to nuclear translocation of apoptosis inducing factor (AIF) in normal skin. The human papillomavirus (HPV) E6 protein prevented release of AIF and other apoptotic factors such as cytochrome c and Omi from mitochondria of UV-damaged primary epidermal keratinocytes and preserved mitochondrial integrity. shRNA silencing of Bak, a target for E6-mediated proteolysis, demonstrated the requirement of Bak for UV-induced AIF release and mitochondrial fragmentation. Furthermore, screening non-melanoma skin cancer biopsies revealed an inverse correlation between HPV status and AIF nuclear translocation. Our results indicate that the E6 activity towards Bak is a key factor that promotes survival of HPV-infected cells that facilitates tumor development.
Similar content being viewed by others
References
Danial NN, Korsmeyer SJ (2004) Cell death: critical control points. Cell 116(2):205–219
Kuwana T, Newmeyer DD (2003) Bcl-2-family proteins and the role of mitochondria in apoptosis. Curr Opin Cell Biol 15(6):691–699
Mikhailov V et al (2003) Association of Bax and Bak homo-oligomers in mitochondria. Bax requirement for Bak reorganization and cytochrome c release. J Biol Chem 278(7):5367–5376
Green DR (2005) Apoptotic pathways: ten minutes to dead. Cell 121(5):671–674
Wei MC et al (2001) Proapoptotic BAX and BAK: a requisite gateway to mitochondrial dysfunction and death. Science 292(5517):727–730
Kandasamy K et al (2003) Involvement of proapoptotic molecules Bax and Bak in tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-induced mitochondrial disruption and apoptosis: differential regulation of cytochrome c and Smac/DIABLO release. Cancer Res 63(7):1712–1721
Green DR, Kroemer G (2004) The pathophysiology of mitochondrial cell death. Science 305(5684):626–629
Saelens X et al (2004) Toxic proteins released from mitochondria in cell death. Oncogene 23(16):2861–2874
Susin SA et al (1999) Molecular characterization of mitochondrial apoptosis-inducing factor. Nature 397(6718):441–446
Cande C et al (2002) Apoptosis-inducing factor (AIF): key to the conserved caspase-independent pathways of cell death? J Cell Sci 115(Pt 24):4727–4734
Cregan SP, Dawson VL, Slack RS (2004) Role of AIF in caspase-dependent and caspase-independent cell death. Oncogene 23(16):2785–2796
Carter BZ et al (2003) Caspase-independent cell death in AML: caspase inhibition in vitro with pan-caspase inhibitors or in vivo by XIAP or Survivin does not affect cell survival or prognosis. Blood 102(12):4179–4186
Cande C et al (2004) AIF and cyclophilin A cooperate in apoptosis-associated chromatinolysis. Oncogene 23(8):1514–1521
Saito M, Korsmeyer SJ, Schlesinger PH (2000) BAX-dependent transport of cytochrome c reconstituted in pure liposomes. Nat Cell Biol 2(8):553–555
Kuwana T et al (2002) Bid, Bax, and lipids cooperate to form supramolecular openings in the outer mitochondrial membrane. Cell 111(3):331–342
Jemal A et al (2004) Cancer statistics 2004. CA Cancer J Clin 54(1):8–29
Goodwin RG, Holme SA, Roberts DL (2004) Variations in registration of skin cancer in the United Kingdom. Clin Exp Dermatol 29(3):328–330
Schwarz A et al (1995) Ultraviolet-B-induced apoptosis of keratinocytes: evidence for partial involvement of tumor necrosis factor-alpha in the formation of sunburn cells. J Invest Dermatol 104(6):922–927
Ichihashi M et al (2003) UV-induced skin damage. Toxicology 189(1–2):21–39
Jackson S et al (2000) Role of Bak in UV-induced apoptosis in skin cancer and abrogation by HPV E6 proteins. Genes Dev 14(23):3065–3073
Shamanin V et al (1996) Human papillomavirus infections in nonmelanoma skin cancers from renal transplant recipients and nonimmunosuppressed patients. J Natl Cancer Inst 88(12):802–811
Harwood CA, Proby CM (2002) Human papillomaviruses and non-melanoma skin cancer. Curr Opin Infect Dis 15(2):101–114
Pfister H (2003) Chapter 8: Human papillomavirus and skin cancer. J Natl Cancer Inst Monogr (31):52–56
Harwood CA et al (2000) Human papillomavirus infection and non-melanoma skin cancer in immunosuppressed and immunocompetent individuals. J Med Virol 61(3):289–297
Jackson S et al (2002) Reduced apoptotic levels in squamous but not basal cell carcinomas correlates with detection of cutaneous human papillomavirus. Br J Cancer 87(3):319–323
Storey A (2002) Papillomaviruses: death-defying acts in skin cancer. Trends Mol Med 8(9):417–421
Akgul B, Cooke JC, Storey A (2006) HPV-associated skin disease. J Pathology 208:165–175
Jackson S, Storey A (2000) E6 proteins from diverse cutaneous HPV types inhibit apoptosis in response to UV damage. Oncogene 19(4):592–598
de Villiers EM et al (2004) Classification of papillomaviruses. Virology 324(1):17–27
Nechushtan A et al (2001) Bax and Bak coalesce into novel mitochondria-associated clusters during apoptosis. J Cell Biol 153(6):1265–1276
Arnoult D et al (2004) Cytomegalovirus cell death suppressor vMIA blocks Bax- but not Bak-mediated apoptosis by binding and sequestering Bax at mitochondria. Proc Natl Acad Sci USA 101(21):7988–7993
Cheng EH et al (2003) VDAC2 inhibits BAK activation and mitochondrial apoptosis. Science 301(5632):513–517
Qin JZ et al (2002) Regulation of apoptosis by p53 in UV-irradiated human epidermis, psoriatic plaques and senescent keratinocytes. Oncogene 21(19):2991–3002
Joseph B et al (2002) Mitochondrial dysfunction is an essential step for killing of non-small cell lung carcinomas resistant to conventional treatment. Oncogene 21(1):65–77
Alonso M et al (2003) Flavopiridol induces apoptosis in glioma cell lines independent of retinoblastoma and p53 tumor suppressor pathway alterations by a caspase-independent pathway. Mol Cancer Ther 2(2):139–150
Gallego MA et al (2004) Apoptosis-inducing factor determines the chemoresistance of non-small-cell lung carcinomas. Oncogene 23(37):6282–6291
Green DR, Evan GI (2002) A matter of life and death. Cancer Cell 1(1):19–30
Sharpe JC, Arnoult D, Youle RJ (2004) Control of mitochondrial permeability by Bcl-2 family members. Biochim Biophys Acta 1644(2–3):107–113
Dohi T et al (2004) Mitochondrial survivin inhibits apoptosis and promotes tumorigenesis. J Clin Invest 114(8):1117–1127
Liu T, Brouha B, Grossman D (2004) Rapid induction of mitochondrial events and caspase-independent apoptosis in Survivin-targeted melanoma cells. Oncogene 23:39–48
Borbely A et al (2006) Effects of human papillomavirus type 16 oncoproteins on survivin gene expression. J Gen Virol 87:287–294
Jonason AS et al (1996) Frequent clones of p53-mutated keratinocytes in normal human skin. Proc Natl Acad Sci USA 93(24):14025–14029
Ren ZP et al (1996) Human epidermal cancer and accompanying precursors have identical p53 mutations different from p53 mutations in adjacent areas of clonally expanded non-neoplastic keratinocytes. Oncogene 12(4):765–773
Cregan SP et al (2002) Apoptosis-inducing factor is involved in the regulation of caspase-independent neuronal cell death. J Cell Biol 158(3):507–517
Leu JI et al (2004) Mitochondrial p53 activates Bak and causes disruption of a Bak-Mcl1 complex. Nat Cell Biol 6(5):443–450
Akgul B et al (2005) The E7 protein of cutaneous human papillomavirus type 8 causes invasion of human keratinocytes into the dermis in organotypic cultures of skin. Cancer Res 65(6):2216–2223
Bull JJ et al (2001) Contrasting localization of c-Myc with other Myc superfamily transcription factors in the human hair follicle and during the hair growth cycle. J Invest Dermatol 116(4):617–622
Mihara M, Moll UM (2003) Detection of mitochondrial localization of p53. Methods Mol Biol 234:203–209
Acknowledgments
The authors are grateful to Drs C.A. Harwood and C.M. Proby (University of London, UK) for tissue biopsies, and to Dr. S. Basu (Cancer Research UK, UK) for critical reading of the manuscript. We also thank Prof. H. Pfister (University of Cologne, Germany) for providing us the retroviral construct pLXSN-8-E6, and Dr. F.A. Rassendren (CNRS, France) for shRNA expression plasmids nd helpful advice. This work was supported by funding from Cancer Research UK. B.A. was the recipient of a grant from the Dr. Mildred Scheel Stiftung / Deutsche Krebshilfe.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Leverrier, S., Bergamaschi, D., Ghali, L. et al. Role of HPV E6 proteins in preventing UVB-induced release of pro-apoptotic factors from the mitochondria. Apoptosis 12, 549–560 (2007). https://doi.org/10.1007/s10495-006-0004-1
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s10495-006-0004-1