769 - Cyclin E1 suppression contributes to sorafenib-induced apoptosis in hepatocellular carcinoma (HCC)

Date 28 September 2012
Event ESMO Congress 2012
Session Publication Only
Topics Hepatobiliary Cancers
Translational Research
Presenter Chiun Hsu
Authors C. Hsu1, D. Ou2, Y. Cheng3, Y. Lin4, Y. Chang5, K. Yeh6, A. Cheng7
  • 1National Taiwan University Hospital, 10002 - Taipei/TW
  • 2Graduate Institute Of Oncology, National Taiwan University College of Medicine, Taipei/TW
  • 3Gradualte Institute Of Medical Technology, National Taiwan University College of Medicine, Taipei/TW
  • 4Department Of Oncology, National Taiwan University Hospital, 10002 - Taipei/TW
  • 5Oncology, National Taiwan University Hospital, Taipei/TW
  • 6Oncology Dept., National Taiwan University College of Medicine, Taipei/TW
  • 7Internal Medicine, National Taiwan University Hospital, Taipei/TW

Abstract

Background

We have found that sorafenib can inhibit cyclin E1 expression in HCC cells, which is independent of the inhibitory effects of sorafenib on mitogen-activated protein kinase-extracellular signal-regulated kinase/extracellular signal-regulated kinase signaling. The present study sought to clarify the role of cyclin E1 in sorafenib-induced apoptosis in HCC.

Methods

A panel of HCC cell lines, including sorafenib-sensitive (Huh-7, HepG2) and sorafenib-resistant (Hep3B, Huh-7R and HepG2R) HCC cells, was tested. Apoptosis was measured by flow cytometry. Knockdown of cyclin E1 expression were used by RNA-interference. Over-expression of cyclin E1 was done by transient transfection of pCMV6-AC-GFP-CCNE1 vector (RG204289; Origene Technologies). The activity of pertinent signaling pathways, cell cycles-related proteins and expression of apoptosis-related proteins were measured by Western blotting.

Results

Cyclin E1 mRNA and protein expressions were suppressed after sorafenib treatment in sorafenib-sensitive but not in sorafenib-resistant HCC cells. The changes in cyclin E2 or cyclin D1 expression after sorafenib treatment were not correlated with sorafenib sensitivity of HCC cells. Knockdown of cyclin E1 expression reversed the resistance of HCC cells to sorafenib in terms of cell growth and apoptosis induction, whereas over-expression of cyclin E1 increased the resistance of HCC cells to sorafenib. Combination of sorafenib and the cyclin-dependent kinase (CDK) inhibitor flavopiridol synergistically inhibited cell growth and induced apoptosis in HCC cells. The synergistic efficacy was associated with suppression of Bcl-XL expression in HCC cells.

Conclusion

Cyclin E1 expression in HCC cells may serve a predictive biomarker for treatment efficacy. Combination of sorafenib and CDK inhibitors may improve the therapeutic efficacy of sorafenib in HCC. (Supported by grants: NSC100-2314-B-002-058-MY3, NSC101-2325-B-002-039, and NHRI-EX101-9911BC)

Disclosure

C. Hsu: Dr Chiun Hsu is a member of the speaker's bureau of Bayer-Schering Pharma.

A. Cheng: Dr Ann-Lii Cheng is a consultant for Sanofi-Aventis Inc.; Pfizer, Bayer Schering Pharma; Bristol-Myers Squibb (Taiwan) Ltd.; Boehringer Ingelheim Taiwan Limited; Novartis Inc.

All other authors have declared no conflicts of interest.