HDAC Inhibitors抑制肝癌細胞生長因子受體表現之研究

Studies of Growth Factor Receptors Inhibition in HCC by HDAC Inhibitors

林佩樺(Pei-Hua Lin)

指導教授 ： 陳青周

國立臺灣大學/醫學院/藥理學研究所/碩士(2010年)

https://doi.org/10.6342/NTU.2010.00656

摘要

肝癌為全世界第五大常見癌症，高居癌症死亡之第三位，且缺乏有效的藥物治療。許多文獻證實，生長因子受體EGFR與c-Met在肝癌均有過度表現，可活化細胞生長之訊號導致癌化。觀察不同HDAC isoform在肝腫瘤細胞株之表現，發現HDAC3表現量與EGFR及c-Met蛋白表現正相關，Huh7細胞之HDAC3表現較多，EGFR、c-Met表現量亦較高。肝腫瘤細胞處理廣效型HDAC抑制劑SAHA在in vitro及in vivo均有抗肝臟腫瘤細胞生長之作用，增加p21表現、引發G2/M arrest及促進細胞凋亡。SAHA亦能抑制EGFR、c-Met蛋白之表現，且SAHA之PARP cleavage和p21增加作用與其抑制EGFR表現相關。將帶有shRNA基因片段之病毒載體感染肝癌細胞，藉由RNA干擾移除HDAC1、2、3和8之基因表現，發現knockdown HDAC3會引發G2/M arrest，並影響EGFR、c-Met蛋白之穩定性，此作用可能是經由促進配體誘發之內吞作用而加速生長因子受體之分解。肝癌細胞給予SAHA或knockdown HDAC3均可抑制EGF誘發之細胞生長，亦可抑制EGF、HGF刺激引發之Akt訊號傳遞。由於HER3之活化可能導致抗藥性的產生，我們進一步發現SAHA或knockdown HDAC3均可抑制HER3蛋白之表現及其磷酸化；將SAHA併用sorafenib在in vitro及in vivo均有較好之腫瘤抑制效果。總結以上結果，HDAC3在調控肝癌細胞生長扮演重要角色，SAHA抑制HDAC3會造成細胞週期之G2/M arrest，使EGFR、c-Met及HER3蛋白之表現降低，並抑制Akt及HER3之磷酸化，進而阻斷調控肝臟腫瘤細胞增生之訊號傳遞。

關鍵字

肝癌 ； 組織蛋白去乙醯酶抑制劑 ； 表皮生長因子接受體 ； 肝細胞生長因子接受體

並列摘要

Hepatocellular carcinoma (HCC) is the fifth most common cancer and the third leading cause of cancer death worldwide. Effective therapeutic options for HCC are limited. There is a large body of evidence that overexpression of EGFR and c-Met contributes to aberrant activation of cell proliferation signaling cascade in human hepatocarcinogenesis. We analyzed distinct expression profiles of HDAC isozymes among HCC cell lines and found that Huh7 expressed higher level of EGFR and c-Met in accordance with an abundance of HDAC3. The pan-HDAC inhibitor SAHA exhibited antitumor effects in vitro and in vivo and induced upregulation of p21, G2/M arrest as well as apoptosis. SAHA also reduced EGFR and c-Met protein expression. Downregulation of EGFR was involved in the SAHA-induced PARP cleavage and increase in p21. When HDAC1, 2, 3 or 8 was knockdown by respective lentiviral vector-expressed shRNA, depletion of HDAC3 was found to lead to the accumulation of cells in G2/M phase. Protein stability of EGFR and c-Met was reduced as well and probably resulted from the accelerated ligand-induced receptor degradation. SAHA or knockdown of HDAC3 inhibited the EGF-induced cell proliferation and the EGF/HGF-induced phosphorylation of Akt. Since HER3 has been reported to mediate drug resistance in many cancers, the HER3 level was analyzed and found that its protein expression and phosphorylation were reduced by SAHA and knockdown of HDAC3. Moreover, SAHA in combination with sorafenib exhibited an improved antitumor effect both in vitro and in vivo. Taken together, our data demonstrated the important role of HDAC3 in the regulation of HCC cell proliferation and survival. Depletion of HDAC3 by SAHA induces G2/M arrest and leads to the downregulation of EGFR, c-Met and HER3, resulting in the inhibition of cell proliferation by blocking Akt and HER3 phosphorylation.

並列關鍵字

HCC ； hepacellular carcinoma ； HDAC inhibitor ； EGFR ； c-Met ； HER3

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