第二型組蛋白去乙醯酶在口腔鱗狀上皮細胞癌之表現

Expression of histone deacetylase 2 (HDAC 2) in oral cancer patients

章浩宏(Hao-Hueng Chang)

指導教授 ： 郭彥彬

國立臺灣大學/牙醫專業學院/臨床牙醫學研究所/博士(2009年)

https://doi.org/10.6342/NTU.2009.10527

摘要

第二型組蛋白去乙醯酶(Histone deacetylase 2, HDAC2)被認為與某些人類腫瘤的發育與進展有關。 本研究先以免疫組織化學染色探討HDAC2於口腔鱗狀上皮細胞癌中的表現。研究結果顯示，HDAC2的陽性染色表現可在80/93 (86%)的口腔癌及11/20 (55%)的口腔上皮變異患者檢體中偵測到。主要出現於上皮細胞之細胞核中。 陽性標記指數(Labeling index, LI) 分別為25.8 ± 26.5% (口腔上皮變異)及 59.8 ± 28.5% (口腔鱗狀細胞癌)。正常口腔組織則無表現。在口腔鱗狀細胞癌的病例中，HDAC2的LI與性別、年齡、口腔習慣上並無顯著的關連。然而，在較後期的癌症分期、較大的腫瘤、或是淋巴轉移的病例中HDAC2皆有較高的表現。在Kaplan-Meier存活率分析方面， 較高的HDAC2表現(LI>50%)、較晚的癌症分期、較大的腫瘤或是具淋巴轉移之案例其存活率皆較低。
由於HDAC2過度表現在實體腫瘤中所扮演的角色至今仍不明瞭，因此我們擬繼續探討HDAC2在臺灣口腔癌癌化的角色。由於前述淋巴轉移的病例中，HDAC2皆有較高的表現， 因此我們首先嘗試探討 HDAC2 是否與癌細胞的移動與侵襲有關。 我們測試了實驗室中所擁有的多株口腔癌細胞株，發現都有HDAC2表現，其中 SAS, Ca9-22, Cal27表現較高， TW2.6, TW1.5, SCC9表現較低。恰與其侵襲能力呈正相關。利用實驗室中所分離出來的TW2.6口腔癌細胞株 及Transwell invasion chamber分離出較具轉移能力的次細胞株，將之命名為CC1-2, -4, -6。發現HDAC2基因表現的強弱與侵襲能力有正相關。因此HDAC2可能經由增強細胞之入侵能力而造成口腔癌侵襲性增強的表現。
本研究進一步以人類口腔癌細胞株SAS及Ca9-22來探討已被證實有很好的口服耐受性的HDACI- suberoyl anilide bishydroxamine (SAHA)對口腔癌細胞的影響。 結果顯示，以0.5-5 μM SAHA處理SAS及Ca9-22 細胞，可以明顯抑制其生長，且濃度愈高或作用時間愈長，抑制效應就愈明顯 (IC50分別為1.5μM & 3μM)。 在西方墨點法分析中，SAHA會增加SAS及Ca9-22細胞 PARP cleavage的情形，亦證實SAHA可引起人類口腔癌細胞的細胞凋亡。因此HDACI可做為未來治療口腔癌的潛力新藥物。
本實驗結果首次顯示出HDAC蛋白的過度表現在口腔癌案例中為一常見之現象，並可能作為一種口腔鱗狀細胞癌之預測因子及未來開發治療用藥之參考。

關鍵字

組蛋白去乙醯酶口腔鱗狀細胞癌

並列摘要

Histone deacetylase 2 (HDAC2) has been implicated in the development and progression of several human tumors. We immunohistochemically examined the expression of HDAC2 protein in 20 cases of oral epithelial dysplasia (OED) and 93 cases of oral squamous cell carcinoma (OSCC). Positive HDAC2 nuclear staining was observed in 80 of the 93 (86%) cases of SCC and 11 of the 20 (55%) cases of ED. The labeling index (LI) for HDAC2 nuclear staining increased significantly from ED (25.8 ± 26.5%) to SCCs (59.8 ± 28.5%) (p < 0.001). No significant correlation was found between the HDAC2 expression level and patient's age, sex, and oral habits in oral SCC patients. However, cancer with advanced stage, larger tumor size, or positive lymph node metastasis had higher level of HDAC2 protein expression. Kaplan-Meier curves showed oral SCC patients with high HDAC2 expression (LI >50 %), advanced stage, larger tumor size, or positive lymph node metastasis had significantly shorter overall survival (p=0.0158, 0.0267, 0.0029 and 0.02514, respectively by log-rank test) than others. The results of this study show for the first time that overexpression of the HDAC protein is a frequent event in oral cancer and could be used as a prognostic factor in oral SCC. We further investigated the role(s) of HDAC2 in oral carcinogenesis. We found that human oral cancer TW2.6 CC-2, -4, -6 cells with higher invasive ability exihibited higher HDAC2 expression.Recent studies have demonstrated that HDAC inhibitors (HDACIs) possess antitumor activity and are well tolerated, supporting the idea that their use might be a specific strategy for treatment of oral cancer. In this study, we investigate the effect of suberoyl anilide bishydroxamine (SAHA, one of the most potent HDACI) on SAS and Ca9-22. Here, we demonstrated that SAHA induces apoptosis in SAS and Ca9-22 cells as evidenced by PARP cleavage and nuclear DNA fragmentation ELISA. In combination with the clinical findings, the present stady demonstrated that HDAC2 may also play a role in regulating the invasive ability of oral cancer cells.

並列關鍵字

histone deacetylases (HDAC) ； Oral squmous cell cancer

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