CYR61在人類胃癌趨化性移動之角色探討

The role of CYR61 in chemotactic migration of gastric cancer

陳俐蓉(Lie-Jung Chen)

指導教授 ： 郭明良

國立臺灣大學/醫學院/毒理學研究所/碩士(2005年)

https://doi.org/10.6342/NTU.2005.00081

摘要

胃癌死亡高居世界癌症死因第二位，主要原因為發生淋巴轉移、腹膜轉移和肝臟轉移，許多研究報導指出腫瘤轉移到特定的器官和腫瘤細胞本身表現chemokine receptor具有相關性，於是我們對於惡性度高的胃癌細胞是否表現特定的chemokine receptor 而促使腫瘤細胞移動能力的增強甚感興趣。先前在實驗室的研究中指出CYR61的表現和腫瘤細胞的惡性度有直接相關，發現胃癌病人的癌化組織中的CYR61蛋白表現量相較於正常組織高，而且淋巴轉移的病人CYR61表現也有提高表現的情形，但是對於CYR61如何調控胃癌細胞轉移的機制仍不清楚。因此我們對於高惡性度的胃癌細胞中，CYR61基因高表現是否和chemokine receptors具有相關性是值得我們進一步探討的。
我們以反轉錄聚合挴鏈鎖反應來篩選在穩定高表現不同程度CYR61的胃癌細胞株之中 chemokine receptor mRNA的表現，研究結果發現CXCR1和CXCR2會隨著CYR61高表現而有被大量調控表現的情形。並利用短暫轉殖不同劑量的CYR61 質體至AGS細胞中，也可偵測到CXCR1和CXCR2蛋白表現量的增加。
同時我們發現在不同的胃癌細胞株，CXCR1和CXCR2蛋白表現量和CYR61也呈現正相關的情形。而且以短暫轉殖antisense-CYR61質體進入高表現CYR61的MKN45 細胞，則抑制了CXCR1和CXCR2的蛋白表現量，這些結果指出CYR61在胃癌細胞中會誘導CXCR1和CXCR2的表現。另外在臨床的觀察也得知病人的胃癌組織中CYR61和CXCR1，CXCR2之間表現具有高相關的情形。我們更進一步探討CXCR1和CXCR2在CYR61高表現的細胞株中的功能性，我們發現重組蛋白質IL-8會誘導胃癌細胞進行非隨機的趨化性移動；當以中和抗體抑制AGS-CYR61細胞株的CXCR1和CXCR2活性時，則降低Cyr61高表現細胞的趨化性移動能力。除此之外我們發現內皮細胞會分泌IL-8蛋白以促進CYR61高表現的細胞進行趨化性移動，並且當以中和抗體抑制IL-8活性時，則AGS/CYR61細胞穿透內皮細胞的能力也隨之降低。因此我們推論內皮細胞可分泌IL-8促使CYR61高表現的胃癌細胞藉由CXCR1和CXCR2的表現進行趨化性移動，進一步穿透內皮細胞進入循環系統，在活體實驗利用雞胚胎模式也驗証我們的推論。最後我們在CYR61調控IL-8 receptors分子機制探討中，發現CYR61會透過受器integrin αVβ3的表現和Src激鋂的磷酸化，經由PI3k-Akt路徑的活化來調控CXCR1和CXCR2蛋白表現量。
綜合以上實驗結果顯示，在惡性度高的胃癌細胞中CYR61高度表現會誘導CXCR1，CXCR2表現，而且透過微環境中內皮細胞所分泌的IL-8和受器交互作用下，促使胃癌細胞依賴CXCR1和CXCR2的活性進行趨化性移動，其可能和腫瘤轉移的器官專一性是有相關聯的，因此期望CYR61調控CXCR1和CXCR2表現的機轉路徑在未來可以作為在活體實驗的治療標的。

關鍵字

胃癌 ； 轉移

並列摘要

Gastric cancer is the second most common cause of cancer mortality worldwide, and development of metastasis to lymph nodes, liver, and peritoneum is responsible for the majority of cancer related death. Metastasizing cells must traverse the endothelial lining of the lymphatic or vascular systems in order to metastasize to distant sites. The previous study demonstrated that expression of CYR61 was correlated with tumor malignancy and lymph node metastasis in gastric cancer patients. It has been reported that tumor cells express specific chemokine receptors that may play roles in determining the sites of metastasis. We thus further investigated whether chemokine receptors are involved in CYR61-mediated cell migration.
Messenger RNA expression of chemokine receptors was screened by RT-PCR in several stable CYR61 transfectant clones. We found that the expression of CXCR1 and CXCR2 in mRNA in AGS/CYR61 cells was strongly higher than AGS parental cells, as well as protein induction level, suggesting that CYR61 up-regulated CXCR1 and CXCR2 expression in human gastric cancer cells. Moreover, clinical study showed that CXCR1 and CXCR2 expression was tightly correlated with CYR61 in gastric tumor patients by RT-PCR and immunohistochemistry analyses. Furthermore, recombinant human IL-8 enhanced the chemotactic migration of CYR61- overexpressing gastric carcinoma cells in a time and dose dependent manner, and consistently, neutralizing antibodies to CXCR1 and CXCR2 significantly attenuated chemotactic migration of IL8-stimulated gastric cells. It was found that IL-8 is the potent chemotactic factor from conditioned medium of HUVEC that induced chemotaxis of CYR61-overexpressing cells, enhanced transendothelial migration dependent on CXCR1, CXCR2 activation in Boyden chamber assay; and active CXCR1 and CXCR2 signalings are necessary for CYR61-overexpressing gastric tumor cells to intravasate monolayer endothelium, and then enter circulating system in chicken embryo model. Our results further delineated the molecular mechanisms that CXCR1 and CXCR2 induced by CYR61 through integrin αvβ3, which is requisite for activation of c-Src and subsequent PI3k-Akt signaling pathways.
Collectively, our present data suggested an association between constitutive expression of CXCR1, CXCR2 receptors and CYR61 in aggressiveness of human gastric carcinoma cells. It implicated that the IL-8 receptor system regulated chemotactic migration of gastric cancer cells, and may be involved in organ-specific gastric carcinomas metastasis and, hence, could be a potential target for therapy.

並列關鍵字

gastric cancer ； chemotaxis ； CYR61

參考文獻

Arias-Salgado, E. G., Lizano, S., Sarkar, S., Brugge, J. S., Ginsberg, M. H., and Shattil, S. J. (2003) Src kinase activation by direct interaction with the integrin beta cytoplasmic domain. Proc. Natl. Acad. Sci. U. S. A. 100: 13298–13302.

Ausprunk, D. H., and Folkman, J. (1977) Migration and proliferation of endothelial cells in preformed and newly formed blood vessels during tumor angiogenesis. Microvasc. Res., 14: 53–65.

Aznavoorian, S., Murphy, A. N., Stetler-Stevenson, W. G., and Liotta, L. A. (1993) Molecular aspects of tumor cell invasion and metastasis. Cancer 71:1368-1383.

Babic, A. M., Chen, C. C., and Lau, L. F. (1999) Fisp12/Mouse connective tissue growth factor mediates endothelial cell adhesion and migration through integrin αvβ3, promotes endothelial cell survival, and induces angiogenesis in vivo. Mol. Cell. Biol.19:2958–2966.

Babic, A. M., Kireeva, M. L., Kolesnikova, T. V., and Lau, L. F. (1998) CYR61, a product of a growth factor-inducible immediate early gene, promotes angiogenesis and tumor growth. Proc. Natl. Acad. Sci. USA 95:6355–6360.