利用蛋白質體學及網路分析探討14-3-3β蛋白在胃癌細胞中的功能角色

Abstract

胃癌是一種普遍且高死亡率的癌症，導致其病患死亡率居高不下的原因主要就是因為缺乏有效的早期診斷工具，而目前可做為胃癌早期診斷的生物標記尚有待開發。因此，我們期待透過腫瘤蛋白質體學技術找出胃癌早期診斷的生物標記分子。在我們初步的研究中，透過二維膠體電泳和質譜分析方法，在比較不同人類胃癌細胞株AGS、N87、TSGH及SC-M1後鑑定出26個顯著不同表現的蛋白質。其中，在蛋白質圖譜中所鑑定到的14-3-3β蛋白在較惡性的胃癌細胞株TSGH及SC-M1中的表現比不具有轉移性的AGS及N87細胞株要高。同時，我們分析了14-3-3β蛋白在腫瘤組織表現量比在正常組織中表現多。進一步我們分析14-3-3β在血液中的表現，也得到相似的結果。綜合以上結果，說明了14-3-3β蛋白可能是具有潛力的早期診斷之生物標記分子。 延續之前的結果，本研究進一步探討14-3-3β在胃癌可能調控的機制。首先，我們在胃癌細胞株中大量表現14-3-3β蛋白，再利用蛋白質體方法分析受其影響的蛋白質。藉由分析這些蛋白質在癌症上所涉及的機制以及他們之間的蛋白質網路關係，我們建立了14-3-3β蛋白在胃癌上可能的調控路徑。我們發現14-3-3β與一系列熱休克蛋白質(Heat shock protein)的啟動有密切關聯，透過這個網路所引發的訊息傳遞也與細胞的癌化有直接的影響。未來，針對這個調控路徑的驗證與更深入的研究將可為日後胃癌的治療提供更明確的目標。

Gastric cancer is the second leading cause of cancer death worldwide. Lacking of early detection marker for this disease is the major reason of such high death rate. In our previous study, we found that 14-3-3β protein levels were evaluated in tumor tissues compared with normal tissues, and serum 14-3-3β levels were also significantly higher than control samples. Higher serum 14-3-3β levels correlated with reduced patient sur-vival rate. On the other hand, over-expression of 14-3-3β enhanced growth, invasiveness and migratory abilities of tumor cells. These results suggest that 14-3-3β is a potential biomarker for detection and prognosis in gastric cancer and regulates aggressive phenotypes of tumor cells. To further elucidate the regulatory mechanism of 14-3-3β on tumor progression, we integrated proteomics and network analyses to construct 14-3-3β-regulated protein-protein interaction networks and their enriched biological functions. Key functional relationships of the networks were revealed, including cell death, apoptosis and phosphorylation. Interestingly, we identified a series of heat shock proteins and other apoptosis related proteins, which had been reported to be involved in malignant progression. These proteins were significantly up-regulated in 14-3-3β-over-expressing tumor cells, and the related protein-protein interaction network is highly connected with cell proliferation and apoptosis, indicating that 14-3-3β could affect growth of tumor cells through regulating these proteins expression. In conclusion, 14-3-3β has a high oncogenic potential in gastric cancer and affects tumor progression through its regulating network.