| Autor: |
Hodul, Pamela J., Dong, Yanbin, Husain, Kazim, Pimiento, Jose M., Chen, Jiandong, Zhang, Anying, Francois, Rony, Pledger, Warren J., Coppola, Domenico, Sebti, Said M., Chen, Dung-Tsa, Malafa, Mokenge P. |
| Předmět: |
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| Zdroj: |
PLoS ONE; Feb2013, Vol. 8 Issue 2, p1-10, 10p |
| Abstrakt: |
Vitamin E δ-tocotrienol has been shown to have antitumor activity, but the precise molecular mechanism by which it inhibits the proliferation of cancer cells remains unclear. Here, we demonstrated that δ-tocotrienol exerted significant cell growth inhibition pancreatic ductal cancer (PDCA) cells without affecting normal human pancreatic ductal epithelial cell growth. We also showed that δ-tocotrienol-induced growth inhibition occurred concomitantly with G1 cell-cycle arrest and increased p27Kip1 nuclear accumulation. This finding is significant considering that loss of nuclear p27Kip1 expression is a well-established adverse prognostic factor in PDCA. Furthermore, δ-tocotrienol inactivated RAF-MEK-ERK signaling, a pathway known to suppress p27Kip1 expression. To determine whether p27Kip1 induction is required for δ-tocotrienol inhibition of PDCA cell proliferation, we stably silenced the CDKN1B gene, encoding p27Kip1, in MIAPaCa-2 PDCA cells and demonstrated that p27Kip1 silencing suppressed cell-cycle arrest induced by δ-tocotrienol. Furthermore, δ-tocotrienol induced p27Kip1 mRNA expression but not its protein degradation. p27Kip1 gene promoter activity was induced by δ-tocotrienol through the promoter's E2F-1 binding site, and this activity was attenuated by E2F-1 depletion using E2F-1 small interfering RNA. Finally, decreased proliferation, mediated by Ki67 and p27Kip1 expression by δ-tocotrienol, was confirmed in vivo in a nude mouse xenograft pancreatic cancer model. Our findings reveal a new mechanism, dependent on p27Kip1 induction, by which δ-tocotrienol can inhibit proliferation in PDCA cells, providing a new rationale for p27Kip1 as a biomarker for δ-tocotrienol efficacy in pancreatic cancer prevention and therapy. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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