Acquired tolerance of hepatocellular carcinoma cells to selenium deficiency: a selective survival mechanism?

Date
2003
Authors
Irmak, M. B.
Ince, G.
Ozturk, M.
Cetin Atalay, R.
Editor(s)
Advisor
Supervisor
Co-Advisor
Co-Supervisor
Instructor
Source Title
Cancer Research
Print ISSN
0008-5472
Electronic ISSN
Publisher
American Association for Cancer Research
Volume
63
Issue
20
Pages
6707 - 6715
Language
English
Journal Title
Journal ISSN
Volume Title
Series
Abstract

Selenium is essential to human health, and its deficiency is associated with different diseases including liver necrosis. Selenium is protective against viral hepatitis and hepatocellular carcinoma (HCC). The underlying molecular mechanisms of selenium effects are not well known. In this study, in vitro response of HCC-derived cell lines to selenium deficiency is examined alone or in conjunction with Vitamin E and copper/zinc. Here, we show that itt vitro selenium deficiency in a subset of HCC-derived cell lines causes oxidative stress and cytochrome c release with subsequent cell death by apoptosis. The oxidative stress and consequent cell death induced by selenium deficiency on these cells are reverted by the antioxidant effect of Vitamin E. However, most HCC cell lines (10 of 13) tolerate selenium deficiency. Consequently, they escape apoptosis. Moreover, nine of these tolerant cell lines have integrated hepatitis B Virus (HBV) DNA in their genomes, and some display p53-249 mutation, indicating past exposure to HBV or aflatoxins, established factors for oxidative stress and cancer risk in liver. An HBV-transfected clone (2.2.15) of the sensitive HepG2 cell line has gained tolerance to selenium deficiency. Our findings indicate that selenium deficiency induces apoptosis in some "hepatocyte-like" cells. However, most HCC cells, particularly HBV-related ones, tolerate selenium deficiency and escape its deadly consequences. Thus, as demonstrated by the gain of survival capacity of apoptosis-sensitive cell lines with Vitamin E, such malignant cells have acquired a selective survival advantage that is prominent under selenium-deficient and oxidative-stress conditions.

Course
Other identifiers
Book Title
Citation
Published Version (Please cite this version)