結直腸癌 (CRC) 在台灣為最致命的癌症中排名前三，約佔所有癌症相關死亡人數的 13%。已經發現許多蛋白質可以調節此類癌症的進展，其中一種重要的蛋白質是 EGFR pathway substrate number 8 (Eps8)。目前已發現 Eps8 是會參與在 Src 和 FAK 介導的細胞遷移和增殖的關鍵介質。 Insulin Receptor Substrate protein of 53 kDa (IRSp53) 是 Eps8 的重要結合夥伴，它也調節 Src 和 FAK 所介導的過程。在線上數據庫比對發現IRSp53S 異構物的高表達與更好的整體存活率相關，而 IRSp58M異構物的高表達與較低的無病存活期相關。分析在各種 CRC 細胞株的IRSp53蛋白異構體表現揭示了 SW480 單獨表達IRSp58M，以及發現SW620 細胞中表達IRSp53S，IRSp53T以及IRSp58M三種異構體。在SW480 細胞中誘導表達IRSp53S 和 IRSp58M 的穩定細胞株研究，我們分析這些細胞無論在軟膠細胞群落形成能力試驗、細胞週期分析和老鼠皮下腫瘤生長，都揭示了 IRSp53S 過表達會減少細胞生長，相反的，IRSp58M 過表達則會促進細胞生長。 在SW480 和 Caco-2 細胞中暫時表現 IRSp53S 和 IRSp58M 則揭示了 Src 和 FAK 的活化結果。 當以Src 抑製劑dasatinib的進一步處理，我們發現IRSp53S、IRSp58M 和 Eps8 過表達對細胞不同程度的敏感化性。西方墨點實驗進一步證實，與 SW480 相比，這些過表達細胞中有活化半胱天冬酶-3 (casapase-3)的趨勢。由於 IRSp53 和 Src 都會調節細胞遷徙能力，IRSp53S、IRSp58M 和 Eps8 的過表達增強了細胞遷移，而處理dasatinib可以降低此種遷移。總體而言，這些數據表明 IRSp53S 和 IRSp58M 在調節細胞生長、遷移和dasatinib的細胞凋亡方面發揮著複雜的作用。

Colorectal cancer (CRC) is ranked top 3 of the most lethal cancer in Taiwan, making up around 13% of all cancer related deaths. Many proteins have been found to regulate the progression of this cancer and one important protein involved is EGFR pathway substrate number 8 (Eps8). Eps8 has been found to be a crucial mediator in Src and FAK mediated cell migration and proliferation. Insulin Receptor Substrate protein of 53 kDa (IRSp53) is an important binding partner of Eps8 that might also regulates Src- and FAK-mediated processes. Online databases suggest the high expression of IRSp53S isoform correlates with better overall survival, whereas the high expression of IRSp58M isoform correlates with lower disease free survival. Characterization of various CRC cell lines reveal the expression of IRSp58M in SW480 and both isoforms being expressed in SW620 cells. Inducible expression of IRSp53S and IRSp58M in SW480 cells were generated and soft agar assay, cell cycle analysis and in vivo tumor growth of these cells reveals the decrease in colony formation in IRSp53S overexpressing cells and the promotion of growth in IRSp58M overexpressing cells. Transient overexpression of IRSp53S and IRSp58M in SW480 and Caco-2 cells reveal the activation of Src and FAK. Further treatment of Src inhibitor Dasatinib indicates various degree of sensitivity in IRSp53S, IRSp58M and Eps8 overexpressing cells. Western blot further confirms the increased caspase 3 activity in these overexpressing cells when compared to SW480. Since IRSp53 and Src both regulate cell motility, overexpression of IRSp53S, IRSp58M and Eps8 enhance cell migration, which is ablated by the treatment of Dasatinib. Overall, these data suggest that IRSp53S and IRSp58M play a complicated role in regulating cell proliferation, migration and Dasatinib-induced apoptosis.

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