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Hepatitis B virus X protein overcomes stress-induced premature senescence by repressing p16(INK4a) expression via DNA methylation.
Cancer Lett. 2010 Feb 28; 288(2):226-35.CL

Abstract

Cellular senescence is an important tumor suppression process under diverse oncogenic conditions, entering a state of irreversible growth arrest to prevent damaged cells from undergoing aberrant proliferation. Developing a means of evading senescence thus seems to be a fundamental task that all cancer cells should solve early on. Here, we show that an oncogenic X protein of hepatitis B virus (HBx) overcomes cellular senescence provoked by a universal premature senescence inducer, H(2)O(2), in human hepatoma cells, as demonstrated by impaired induction of senescence-associated biomarkers, including morphological change, G(1) arrest, and beta-galactosidase activity, in the presence of HBx. HBx induced DNA hypermethylation of p16(INK4a) promoter and subsequently interfered action of transcription factors like Ets1 and Ets2 activated by H(2)O(2) through the p38(MAPK) pathway, resulting in inhibition of its transcription. Down-regulation of p16(INK4a) expression by HBx subsequently led to activation of G(1)-CDKs, phosphorylation of Rb, activation of E2F1, and finally evasion from G(1) arrest induced by H(2)O(2). Levels of another senescence regulator, p21(waf1), however, were not affected by HBx under our senescence-inducing conditions. In addition, the potentials of HBx to inactivate Rb and subsequently inhibit cellular senescence almost completely disappeared when levels of p16(INK4a) were recovered either by exogenous complementation or inhibition of the promoter hypermethylation. To our knowledge, our present study represents the first report that an oncogenic virus evades cellular senescence through epigenetic down-regulation of p16(INK4a) expression.

Authors+Show Affiliations

Department of Microbiology, Pusan National University, Busan, Republic of Korea.No affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

19656618

Citation

Kim, Ye-Jin, et al. "Hepatitis B Virus X Protein Overcomes Stress-induced Premature Senescence By Repressing p16(INK4a) Expression Via DNA Methylation." Cancer Letters, vol. 288, no. 2, 2010, pp. 226-35.
Kim YJ, Jung JK, Lee SY, et al. Hepatitis B virus X protein overcomes stress-induced premature senescence by repressing p16(INK4a) expression via DNA methylation. Cancer Lett. 2010;288(2):226-35.
Kim, Y. J., Jung, J. K., Lee, S. Y., & Jang, K. L. (2010). Hepatitis B virus X protein overcomes stress-induced premature senescence by repressing p16(INK4a) expression via DNA methylation. Cancer Letters, 288(2), 226-35. https://doi.org/10.1016/j.canlet.2009.07.007
Kim YJ, et al. Hepatitis B Virus X Protein Overcomes Stress-induced Premature Senescence By Repressing p16(INK4a) Expression Via DNA Methylation. Cancer Lett. 2010 Feb 28;288(2):226-35. PubMed PMID: 19656618.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Hepatitis B virus X protein overcomes stress-induced premature senescence by repressing p16(INK4a) expression via DNA methylation. AU - Kim,Ye-Jin, AU - Jung,Jin Kyu, AU - Lee,Sun Young, AU - Jang,Kyung Lib, Y1 - 2009/08/04/ PY - 2009/04/22/received PY - 2009/06/30/revised PY - 2009/07/10/accepted PY - 2009/8/7/entrez PY - 2009/8/7/pubmed PY - 2010/2/26/medline SP - 226 EP - 35 JF - Cancer letters JO - Cancer Lett. VL - 288 IS - 2 N2 - Cellular senescence is an important tumor suppression process under diverse oncogenic conditions, entering a state of irreversible growth arrest to prevent damaged cells from undergoing aberrant proliferation. Developing a means of evading senescence thus seems to be a fundamental task that all cancer cells should solve early on. Here, we show that an oncogenic X protein of hepatitis B virus (HBx) overcomes cellular senescence provoked by a universal premature senescence inducer, H(2)O(2), in human hepatoma cells, as demonstrated by impaired induction of senescence-associated biomarkers, including morphological change, G(1) arrest, and beta-galactosidase activity, in the presence of HBx. HBx induced DNA hypermethylation of p16(INK4a) promoter and subsequently interfered action of transcription factors like Ets1 and Ets2 activated by H(2)O(2) through the p38(MAPK) pathway, resulting in inhibition of its transcription. Down-regulation of p16(INK4a) expression by HBx subsequently led to activation of G(1)-CDKs, phosphorylation of Rb, activation of E2F1, and finally evasion from G(1) arrest induced by H(2)O(2). Levels of another senescence regulator, p21(waf1), however, were not affected by HBx under our senescence-inducing conditions. In addition, the potentials of HBx to inactivate Rb and subsequently inhibit cellular senescence almost completely disappeared when levels of p16(INK4a) were recovered either by exogenous complementation or inhibition of the promoter hypermethylation. To our knowledge, our present study represents the first report that an oncogenic virus evades cellular senescence through epigenetic down-regulation of p16(INK4a) expression. SN - 1872-7980 UR - https://www.unboundmedicine.com/medline/citation/19656618/Hepatitis_B_virus_X_protein_overcomes_stress_induced_premature_senescence_by_repressing_p16_INK4a__expression_via_DNA_methylation_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S0304-3835(09)00494-7 DB - PRIME DP - Unbound Medicine ER -