β-1, 3-半乳糖基轉移酶5及Globo-系列醣神經鞘脂質在MCF-7乳癌細胞遷移與貼附角色之探討

The roles of β-1, 3-galactosyltransferasee 5 and globo series glycosphingolipids in MCF-7 breast cancer cells migration and adhesion

黃子瑋(Tz-Wei Huang)

指導教授 ： 宋麗英

國立臺灣大學/生物資源暨農學院/生物科技研究所/碩士(2022年)

https://doi.org/10.6342/NTU202202629

摘要

乳癌是嚴重的全球性疾病之一，在臺灣每年約有10,000名女性被診斷出癌症，此外每年更是有約2,000名臺灣婦女死於乳癌。根據統計，乳癌轉移到次級器官是乳癌病患存活率下降的主要原因，然而乳癌轉移 (metastasis) 機制仍充滿未知。目前研究指出Globo-系列醣神經鞘脂質 (globo series glycosphingolipids) 中的SSEA3、SSEA4及Globo H專一表現於乳癌細胞表面。且前人文獻中發現若將乳癌細胞株MBA-MB-231 (ER-, PR- and HER2-) knockdown 合成SSEA3的酵素β-1, 3-半乳糖基轉移酶5 (B3GALT5) ，則會導致細胞降低遷移 (migration)及貼附 (adhesion) 的能力。因此本研究希望進一步釐清globo series glycosphingolipids在乳癌轉移過程中所扮演的角色。本試驗藉由乳癌細胞株MCF-7 (ER+¬, PR+ 以及GR+) 中過度表現B3GALT5，發現 MCF-7不僅展現上皮細胞的特色，並降低間葉細胞生物標的，同時也降低其細胞遷移與貼附的能力。此結果指示globo series glycosphingolipids在MCF-7及 MBA-MB-231中可能具有不同的功能。此外，我們發現過度表現B3GALT5所導致的細胞轉移能力缺失，可藉由knockdown合成Globo H的酵素FUT1達成修復，然而knockdown合成SSEA4的酵素ST3GAL2，卻無法修復此等功能。上述結果指示Globo H的表現可能會抑制MCF-7細胞轉移能力。總結來說，在MCF-7中過度表現B3GALT5會提升Globo H及SSEA4表現量而非SSEA3，但僅有Globo H表現量提升會抑制細胞遷移及貼附的能力。本試驗結果指出在不同乳癌細胞型態中，Globo-系列醣神經鞘脂質可能具有不同的功能，更進一步了解globo series glycosphingolipids在乳癌細胞轉移機制中所扮演的角色，將有助於乳癌治療策略的研發。

關鍵字

乳癌 ； β-1, 3-半乳糖基轉移酶5 ； Globo-系列醣神經鞘脂質 ； 細胞遷移 ； 細胞貼附 ； MCF-7乳癌細胞株

並列摘要

Breast cancer is among the leading causes of death worldwide. In Taiwan, about 10,000 cases are diagnosed and approximately 2,000 women die from breast cancer per year. Despite the fact that metastasis is the major cause of cancer deaths, the underlying mechanisms remain poorly understood. SSEA3, SSEA4 and Globo H are globo series glycosphingolipids (GSLs) specifically expressed on the surface of breast cancer cells. Knockdown of β1,3-Galactosyltransferase 5 (B3GALT5), the enzyme catalyzes the formation of SSEA3, in breast cancer cell line MBA-MB-231 (negative for ER, PR and HER2), has been shown to decreases cell migration and adhesion. Hence, in this study, we aim to understand the roles of globo series GSLs and signaling pathways involved in breast cancer metastasis. By overexpression of B3GALT5 in breast cancer cell line MCF-7 (positive for ER, PR and GR), we found that MCF-7 not only exhibits features of epithelial cells, but also decreased cell migration, adhesion and the expression of mesenchymal markers. These results indicate that globo series GSLs might have different functions between MCF-7 and MBA-MB-231. In addition, overexpression of B3GALT5 in MCF-7 impaired cell migration and adhesion, which could be recovered by knockdown of FUT1, the Globo H biosynthetic enzyme. In contrast, knockdown of ST3GAL2, the SSEA4 biosynthetic enzyme, would not affect cell migration and adhesion in B3GALT5-overexpression cells. These data suggesting the expression of Globo H might inhibit the cell motility of MCF-7. Collectively, our findings indicated that overexpression of B3GALT5 in MCF-7 promotes the expression of Globo H and SSEA4 instead of SSEA3. Moreover, only the increasing of Globo H inhibits migration and adhesion of MCF-7 cells. The globo series GSLs might play different roles in different breast cancer cell types. Further understanding the mechanism of metastasis will help us to develop new therapeutic strategy for breast cancer.

並列關鍵字

breast cancer ； B3GALT5 ； globo series glycosphingolipids ； migration ； adhesion ； MCF-7 breast cancer cell line

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