Semaphorin3E及其受體Plexin D1促進卵巢子宮內膜癌侵略性生長現象之分子機制探討

Abstract

惡性卵巢子宮內膜癌在上皮性卵巢癌佔有10-20%的比率，其抵抗化學治療及伴隨著癌症轉移的特性，使卵巢子宮內膜癌成為適合研究卵巢衍生癌症進程的模型。在P0及P4這兩株分別為低及高侵略性的卵巢子宮內膜癌細胞株中，我們發現於第三類semaphorin分子中，Sema3E在高侵略性的P4細胞株中有顯著的表現，而Sema3E的受體Plexin D1和/或neuropilins的表現量則無顯著差異。在35例選自臺大醫院診斷為卵巢子宮內膜癌的病人中，經由免疫組織化學染色法證明，Sema3E的表現量與癌症惡性程度在統計上具有顯著相關性。在wound healing以及Transwell chamber的實驗中，發現轉染到低侵略性P0細胞中的Sema3E，會增加細胞侵略性及其移動的能力，並與Sema3E表現濃度成正相關。活體實驗中，將大量表現Sema3E分子的P0細胞株，異體移植至SCID mice後，發現其兩邊肺臟有多處癌症轉移。不表現Sema3E的P0細胞株則無此情形。再者，p87-Sema3E及furin作用後的p61-Sema3E同樣會對腫瘤細胞的侵略及移動造成影響。在利用siRNA抑制Plexin D1表現後，Sema3E即使大量表現也不再具有刺激細胞侵略生長和轉移的能力。我們的研究提出一個重要的發現：大量表現Sema3E，會以autocrine和/或paracrine的方式促進癌症侵略性與轉移，並且受到Plexin D1訊息傳導的調控。

Malignant ovarian endometrioid carcinomas, usually accompanied with metastasis upon diagnosis, account for 10 to 20% of epithelial ovarian cancers (EOCs) and are refractory to chemotherapy. Consequently, ovarian endometrioid carcinomas can serve as a promising model to study cancer progression originated from ovaries. Using two well-established human endometrioid carcinoma cell lines with different ability in invasion (P0 cells: low invasive, P4 cells: high invasive), we found that among all class 3 semaphorins, Sema3E is significantly over-expressed in the more invasive endometrioid carcinoma cells. However, the receptor for Sema3E, Plexin D1 and/or neuropilin, shows no difference in expression level between these cell lines. Statistical analysis of 35 patients with ovarian endometrioid carcinomas diagnosed from 1999 to 2005 at NTUH demonstrated positive parallel correlation between tumor grade and Sema3E expression level assessed by immunohistochemistry. When exogenous Sema3E was stably introduced into the low-invasive P0 cells, Sema3E augmented cellular invasiveness and migration in a concentration-dependent way as assessed by wound healing and Transwell chamber assay in vitro. In vivo, xenografted P0 cells with stably expressed Sema3E resulted in multi-focal tumor metastasis in bilateral lungs of SCID mice, in strong contrast to non-metastasis of P0 cells without Sema3E expression. We further revealed that both furin-cleaved p61-Sema3E and unprocessed p87-Sema3E enhance cellular invasiveness and migration to the similar effect. When Plexin D1 was functionally knocked-down by siRNA in the presence of over-expressed Sema3E, Sema3E no longer promoted cellular invasive and migratory capability. Our research strongly argues for the pivotal role of Plexin D1 signaling pathway triggered by over-expressed Sema3E in the regulation of invasiveness and migration ability of ovarian endometrioid carcinoma via an autocrine and/or paracrine manner.