整合素ανβ6对结肠癌细胞胞外基质降解的调控作用

目的 探讨整合素ανβ6在结肠癌细胞侵袭中的作用,并揭示癌细胞调控胞外基质降解的相关分子机制.方法 利用质粒构建ανβ6特异性siRNA表达载体,细胞侵袭实验检测沉默ανβ6对结肠癌细胞HT29体外侵袭能力的影响;分别通过Western blot实验、明胶酶谱实验检测沉默ανβ6对结肠癌细胞胞外信号调节激酶(ERK)、尿激酶型纤溶酶原激活物(uPA)及基质金属蛋白酶(MMP-2、MMP-9)表达的影响;3H]标记的Ⅳ型胶原降解分析检测沉默ανβ6对结肠癌细胞胞外基质降解能力的影响.结果 特异性siRNA表达载体可有效抑制HT29细胞中ανβ6的表达和结肠癌细胞的体外侵袭能力,显著抑制结肠癌细胞ERK1/2的表达,并抑制其活化形式磷酸化ERK1/2的表达;沉默ανβ6表达显著抑制结肠癌细胞uPA,pro-MMP-9和pro-MMP-2的分泌,以及丝裂原活化蛋白激酶(MAPK)依赖的胞外基质降解.结论 整合素ανβ6通过MAPK信号通路调控uPA、MMP-9和MMP-2的分泌及活性,从而调控细胞外基质的降解,在结肠癌侵袭转移中发挥了重要作用.

The role of integrin ανβ6 in regulation of extracellular matrix degradation of colon cancer cells

Objective To investigate the roles of integrin ανβ6 in the invasion of colon cancer cells and its molecular mechanisms for regulation of the extracellular matrix (ECM) degradation.Methods The RNA interfering technique was used to downregulate the expression of ανβ6 in colon cancer cells. The expression of ανβ6 in transfected cells was determined by RT-PCR and Western blot.The cell invasive capacity was evaluated by reconstituted basement membrane invasion assay. Western blot and gelatin zymography were used to determine whether the reduced αvβ6 expression affects extracellular signal-regulated kinase (ERK), P-ERK, urokinase-type plasminogen activator (uPA) and matrix metalloproteinases (MMPs) expressions. 3H]-labelled type Ⅳ collagen degradation assay was performed to asess if supression of integrin ανβ6 inhibits extracellular matrix degradation.Results Specific siRNA inhibited the expression of ανβ6 in both the protein and mRNA levels in HT29 cells. Down regulation of integrin ανβ6 inhibited ERK, P-ERK1/2 expressions, and the secretion of uPA. pro-MMP-9 and pro-MMP-2 in tumor conditioned medium. Supression of integrin ανβ6 inhibited MAPK dependent 3H]-labelled type Ⅳ collagen degradation. Conclusions These data in our study demonstrats that integrin ανβ6 plays important roles in the invasion of colon cancer cells. The ανβ6 regulates the secretion levels of uPA, pro-MMP-9, pro-MMP-2 and the ECM degradation through the MAPK pathway.