Metastatic colon cancer is a major cause of deaths among colorectal cancer (CRC) patients. Elevated expression of kallikrein 6 (KLK6), a member of a kallikrein subfamily of peptidase S1 family serine proteases, has been reported in CRC and is associated with low patient survival rates and poor disease prognosis. We knocked down KLK6 expression in HCT116 colon cancer cells to determine the significance of KLK6 expression for metastatic dissemination and to identify the KLK6-associated microRNAs (miRNAs) signaling networks in metastatic colon cancer. KLK6 suppression resulted in decreased cells invasion in vitro with a minimal effect on the cell growth and viability. In vivo, animals with orthotopic colon tumors deficient in KLK6 expression had the statistically significant increase in survival rates (P=.005) and decrease in incidence of distant metastases. We further performed the integrated miRNA and messenger RNA (mRNA) expression profiling to identify functional miRNA-mRNA interactions associated with KLK6-mediated invasiveness of colon cancer. Through bioinformatics analysis we identified and functionally validated the top two up-regulated miRNAs, miR-182 and miR-203, and one down-regulated miRNA, miRNA-181d, and their seven mRNA effectors. The established miRNA-mRNA interactions modulate cellular proliferation, differentiation and epithelial-mesenchymal transition (EMT) in KLK6-expressing colon cancer cells via the TGF-β signaling pathway and RAS-related GTP-binding proteins. We confirmed the potential tumor suppressive properties of miR-181d and miR-203 in KLK6-expressing HCT116 cells using Matrigel invasion assay. Our data provide experimental evidence that KLK6 controls metastasis formation in colon cancer via specific downstream network of miRNA-mRNA effectors.

中文翻译：

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组织激肽释放酶相关肽酶介导的结肠癌侵袭的特定microRNA-mRNA调控网络6。

转移性结肠癌是大肠癌（CRC）患者死亡的主要原因。激肽释放酶6（KLK6）是肽酶S1家族丝氨酸蛋白酶激肽释放酶亚家族的成员，在CRC中已有报道，其表达升高与患者生存率低和疾病预后不良有关。我们敲低了HCT116结肠癌细胞中的KLK6表达，以确定KLK6表达对于转移性传播的意义，并确定了转移性结肠癌中与KLK6相关的microRNA（miRNA）信号网络。KLK6抑制导致体外细胞侵袭减少，对细胞生长和活力的影响最小。在体内，KLK6表达不足的原位结肠肿瘤动物的存活率具有统计学上的显着提高（P =。005）并减少远处转移的发生率。我们进一步进行了整合的miRNA和信使RNA（mRNA）表达谱分析，以鉴定与KLK6介导的结肠癌浸润相关的功能性miRNA-mRNA相互作用。通过生物信息学分析，我们鉴定并功能验证了前两个上调的miRNA，miR-182和miR-203，以及一个下调的miRNA，miRNA-181d，及其七个mRNA效应子。已建立的miRNA-mRNA相互作用通过TGF-β信号通路和RAS相关GTP结合蛋白调节表达KLK6的结肠癌细胞中的细胞增殖，分化和上皮-间质转化（EMT）。我们使用基质胶侵袭试验证实了在表达KLK6的HCT116细胞中miR-181d和miR-203的潜在抑癌特性。