| Abstract: | 蛋白質精胺酸甲基化為一種重要的轉譯後修飾，調控細胞內多種生理反應，如訊息傳遞、轉錄調節、DNA修補和RNA運輸，而蛋白質精胺酸甲基轉移酶 (PRMT)會催化蛋白質精胺酸甲基化。研究指出多種癌症都和PRMT的失調和過度表達有關聯。然而目前仍然沒有蛋白質精胺酸甲基化和頭頸癌的相關研究。口腔癌占頭頸癌的最大宗，所以本研究利用口腔細胞(S-G)和口腔癌細胞(SAS, OECM-1, HSC-3, SCC-9)來探討蛋白質精胺酸甲基化和頭頸癌的關聯。利用人類其它癌細胞株乳癌(MCF7) 和子宮頸癌(HeLa)來當做對照。利用不對稱性甲基化抗體 (ADMA)來偵測，發現HeLa, MCF-7、S-G、SAS和OECM-1的ADMA表現，高於HSC-3和SCC-9的ADMA表現。所有細胞都有表現PRMT1，而HSC-3和SCC-9的PRMT1表現低於其他細胞株(HeLa, MCF-7、S-G、 SAS和OECM-1)，根據以上結果發現PRMT1和ADMA的表現量一致。有趣的是口腔癌細胞株SAS和OECM-1的生長速度都快於HSC-3，和PRMT1和ADMA的表現相似。接著我們利用間接甲基抑制劑 (AdOx)來探討精胺酸甲基化對細胞的影響。當加了AdOx以後會抑制細胞ADMA表現、細胞增生(proliferation)還有細胞遷移 (migration)。然後利用PRMT1 siRNA降低口腔癌細胞PRMT1 50%的表現，但是無法有效降低ADMA表現，也無法降低細胞增生，還有無法降低細胞遷移能力。所以接下來更進一步研究大量降低PRMT1表現，或者是剔除 (knockout) PRMT1的表現，來探討蛋白質精胺酸甲基化對頭頸癌之間的關聯。
Protein arginine methylation is a posttranslational modification implicated in signal transduction, gene transcription, DNA repair and RNA processing. Overexpression or deregulation of protein arginine methyltransferases (PRMTs) have been reported to be associated with various cancers. However, there have been no reports studying protein arginine methylation in head and neck cancer (HNC). Oral cancer accounts for the largest group in head and neck cancers. In this study we thus investigate the involvement of the modification in HNC using oral (S-G) and oral cancer cell lines(SAS, OECM-1, HSC-3, SCC-9). Other human cancer cell lines such as MCF7 (breast cancer cell line) and HeLa (breast cancer cell line) are included for comparison. The level of asymmetric dimethylarginine (ADMA) are high in HeLa, MCF-7, S-G, SAS, OECM-1, and low in HSC-3 and SCC-9 as detected by an ADMA-specific antibody. The predominant PRMT1 is expressed in all cancer cell lines, and the protein levels of PRMT1 in HSC-3 and SCC-9 are lower than that in other cell lines, generally consistent with the levels of ADMA signals. Interestingly, growth rate of SAS and OECM-1 is higher than that of HSC-3, similar to the level of PRMT1 and ADMA. We then treated the cells with an indirect methyltransferase inhibitor AdOx. AdOx treatment decrease ADMA level, cell proliferation and cell migration. Knockdown PRMT1 expression by siRNA to about 50%, however, did not decrease ADMA level, cell proliferation and cell migration of the oral cancer cells. Further investigation to knockout specific PRMTs in the oral cancer cell lines should provide more valuable information for protein arginine methylation in HNC. |
