以蛋白體學技術在人類肺腺癌細胞上鑑定microRNA-372目標蛋白

微型核醣核酸 (microRNA) 是一段由長度約18-24 個核苷酸所組成的內生性單股核糖核酸，在生物體內經由轉錄後基因沉默 (post-transcriptional gene silence) 來調控基因表現，主要透過和目標 mRNA 的三端不轉錄區域 (3’-UTR) 形成互補進而抑制蛋白轉譯或造成 mRNA 水解，microRNA在生物體內參與諸多生理現象，包含細胞增生、分化與細胞凋亡等。近年來的研究顯示 microRNA 可能當作抑癌基因 (tumor suppressor) 或致癌基因 (oncogene) ，一旦 microRNA 不正常的表現就可能造成癌症的發展與進程。因為 microRNA 和其目標結合不須完全互補，因此增加了科學家找尋的困難，至今對於 microRNA 的目標蛋白了解仍有限。肺癌因為具有早期不易發現、惡性度高、易轉移、死亡率高等特性，因此近年來居於台灣地區癌症造成死亡的首位，尤以非小細胞肺癌更為嚴重。最近研究發現利用五個 microRNA 共同組成的標誌可以預測肺癌病人的存活率，其中之ㄧ的 miRNA-372 更會增強肺腺癌細胞株的侵襲能力，推測在肺癌轉移時可能扮演重要角色。而先前在睪丸生殖細胞癌 (testicular germ cell tumor) 中發現 miRNA-372會抑制 LATS2 的表現促使細胞快速增生導致癌症。本篇論文的研究目標為利用蛋白質體學的技術找出 miRNA-372 所調控的蛋白，近一步了解其造成肺癌侵襲和轉移的機制。首先利用 2D-DIGE 分析肺腺癌細胞株 CL 1-0 在大量表現 miRNA-372 後造成蛋白表現量的變化，發現有18個蛋白表現量降低，12 個表現量增加。之後利用軟體預測出有7 個蛋白的 3’-UTR含有 miRNA-372 的結合位，同時我們利用資料庫分析這 30 個蛋白預測他們可能參與的訊息傳遞網路，結果發現這些蛋白可能參與在 MAPK pathway 及細胞骨架的重新組建，這些都可能增強癌細胞的侵襲能力，另外在這些傳遞網路中我們更發現了 20 個蛋白可能含有 miRNA-372 的結合位。未來可望針對這些結果做更進一步的驗證以探討其生理意義，並以這些資訊來闡明 miRNA-372 的致病機制。

關鍵字

miRNA-372 ；轉移；肺腺癌； 2D-DIGE ； MAPK pathway ；細胞骨架重新組建

並列摘要

MicroRNAs are 18–24 nt single-strand, small non-coding RNAs that can act as endogenous RNA interference. They can negatively regulate the expression of hundreds of their target genes by translational repression or mRNA cleavage through partial complementary to the 3’-UTR of these targets. MicroRNAs are involved in a wide range of biological functions, such as cellular proliferation, differentiation and apoptosis. Recent evidence indicates that microRNAs may function as tumor suppressors or oncogenes, thus alteration in microRNA expression may play a critical role in tumorigenesis and cancer progression. Until now, the molecular basis of miRNA-mediated gene regulation and the effect of these genes on tumor growth remain largely unknown because of our limited understanding of miRNA targets. Lung cancer, predominant non-small-cell lung cancer (NSCLC), is the leading cause of cancer death in Taiwan for recent years because of the symptoms of delayed-diagnosis, malignancy, metastatic capacity and highly-mortality rate. The evidence obtained by Yu. et. al demonstrate that five-microRNA signature can predict survival in lung cancer patients. One of them is miRNA-372 which can significantly increase the invasion ability of cancer cells, and may play significant roles in the metastasis process. In the previous studies, miRNA-372 was reported to act as oncogene in testicular germ cell tumors by direct inhibition of the tumor suppressor LATS2 expression, thus permitting proliferation and tumorigenesis. The major interest of this study is to find out miRNA-372 targets and investigate the cellular mechniams involved in miRNA-372 overexpression. We used the 2D-DIGE analyze the differential protein expression between the lung adenocarcinoma cell line CL1-0 that stably over-express miRNA-372 and vector only. Eighteen proteins were down-regulated and twelve proteins were up-regulated after miRNA-372 overexpression. Using target prediction programs, we found seven proteins may have miRNA-372 target site. The differential expressed proteins were analysed by the signal transduction database tool and found them involved in MAPK pathway and cytoskeleton remodeling. The enhanced invasion ability may be caused by these pathway. Among the protein in these networks, we found more twenty proteins that have potential miRNA-372 target site. In the future, these miRNA-372 regulations and their physiological roles need to be further validated.

並列關鍵字

miRNA-372 ； metastasis ； lung adenocarcinoma ； 2D-DIGE ； MAPK pathway ； cytoskeleton remodeling

參考文獻

36. 行政院衛生署.2005.94年行政院衛生署死因統計系列

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以蛋白體學技術在人類肺腺癌細胞上鑑定microRNA-372目標蛋白

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