卵巢亮細胞癌中腫瘤抑制基因 SFRP 基因啟動子甲基化之分析
Analysis of the methylation status of the SFRP genes in ovarian clear cell carcinoma
中文摘要
腫瘤抑制基因啟動子高度甲基化是造成基因不正常表現的機制之一。SFRPs (secreted frizzled-related proteins) 是細胞外的分子能拮抗 Wnt 訊息傳遞。本研究 針對在台灣發生率佔卵巢癌 12%的卵巢亮細胞癌探討 SFRP 基因群啟動子甲基化 的情形以了解此種癌症形成的分子機制。結果顯示 SFRP5 基因啟動子甲基化在 卵巢亮細胞癌檢體中的比例為 42% (5/12) ，在卵巢亮細胞癌細胞株的比例為 100% (5/5) ，但於良性卵巢囊腫檢體的比例為 0% (0/15) ，漿液性卵巢癌檢體的 比例為 20% (3/15) 。而 SFRP1 啟動子只有在 40% (2/5) 的卵巢亮細胞癌細胞株 呈現甲基化的情形，於卵巢亮細胞癌檢體、良性卵巢囊腫檢體及漿液性卵巢癌檢 體 SFRP1 啟動子都是沒有甲基化。以正常淋巴球細胞中的 SFRP5 表現量為基 準，在測試的卵巢亮細胞癌細胞株中有 80% (4/5) 有 SFRP5 的表現。且以去甲 基藥物 5＇-aza-2＇-deoxycytidine (5-aza-dC) 處理十五天後，SFRP5 的 mRNA 在 卵巢亮細胞癌細胞株中有 60% (3/5) 會上升。SFRP1 在卵巢亮細胞癌細胞株有 40% (2/5) 是沒有表現，但在去甲基藥物處理十五天後，SFRP1 的表現量並無差 異。此外，實驗結果也顯示加入去甲基藥物，可以抑制卵巢亮細胞癌細胞株的生 長速度 (cell proliferation) 及移行能力 (migration) 。
英文摘要
Tumor suppressor genes are known to be inactivated by epigenetic modifications including promoter methylation. Secreted frizzled-related proteins (SFRPs) are extracellular signaling molecules that antagonize the Wnt signaling pathway. Ovarian clear cell carcinoma constitutes 12% of surface epithelial ovarian cancer in Taiwan.
However, the role of SFRP genes in ovarian clear cell carcinoma molecular
mechanism remains unknown. We investigated the SFRP1 and SFRP5 promoter status and demonstrated that SFRP5 gene promoter was methylated in 42% (5/12) ovarian clear cell carcinoma tissues and in 100% (5/5) ovarian clear cell carcinoma cell lines, compared with 0% (0/15) benign ovarian cyst and 20% (3/15) serous ovarian
carcinoma tissues. And the SFRP1 gene promoter methylated only in 40% (2/5) ovarian clear cell carcinoma cell lines. Our results show that endogenous SFRP5 mRNA expression can be detected in four (80%) of the five ovarian clear cell carcinoma cell lines and is higher than that detected in normal lymphocytes.
Treatment with the demethylating agent 5-aza-2'- deoxycytidine for 15 days rescued SFRP5 mRNA expression (60%, 3/5). Endogeous SFRP1 mRNA expression is absent
in two (40%) of the five ovarian clear cell carcinoma cell lines. But treatment with the demethylating agent did not rescue SFRP1 mRNA expression nor restore SFRP1 promoter methylation atatus. We also find that suppressed ovarian cell carcinoma cell growth and migration ability.
