| Colorectal cancer is one of the most common malignant tumors worldwide. Report by the American Cancer Society in 2015 shows that the morbidity and mortality of colorectal cancer still ranks the third worldwide. Although the introduction of novel chemotherapies and targeted agents has acquired significant advances in the treatment of metastatic colorectal cancers, approximately 60% of patients receiving curative resection will undergo local recurrence or distant metastases. Therefore, to facilitate clinical novel therapy, a thorough understanding of the molecular mechanisms of colorectal cancer metastasis is urgently required.Tumor microenvironment not only provides plenty of nutrition for cancer growth, but also facilitates colorectal cancer metastasis by regulating some significant signaling pathways. Cancer associated fibroblasts (CAFs) being considered the dominating component of tumor microenvironment play an important role during colorectal cancer metastasis. Compared with normal fibroblasts (NFs),32 genes of CAFs are hypermethylation and 26 genes are hypomethylation, and the CAFs express higher level of FAP, α-SMA, POSTIN and so on. However, mechanisms underlying the regulatory effect of CAFs on cancer cells’metastasis are still largely unknown. The aberrant activation of Wnt/β-catenin signaling pathway plays critical roles on regulating the development and progression of colorectal cancer. Do CAFs promote cancer metastasis by regulating Wnt/β-catenin signaling pathway? Depending on the difference of genes between NFs and CAFs, what are the effects of NFs on Wnt/β-catenin signaling and biological behaviors on colorectal cancer?First of all, we used tissue explantation method to detach and purify CAFs and NFs from the center of tumor and the border of noncancerous colorectal tissue respectively from patients with colorectal cancer. And the CAFs and NFs were identified by Western Blot and Immunofluorescence assay. Second, we detected the degree of activation and senescence of CAFs and NFs. The result is that the degree of activation and senescence of CAFs is higher than that of NFs. When CAFs co-cultured with tumor cells, they promoted the ability of migration of tumor cells and downregulated the epithelial marker E-Cadherin and upregulated the mesenchymal marker Vimentin and Fibronectin of tumor cells. In other words, CAFs promoted epithelial-mesenchymal transition(EMT) of colorectal cancer cells. Meanwhile, Wnt/β-catenin signaling relative factors such as S552 and DVL3 were also upregulated, indicating that Wnt/β-catenin signaling was activated. After culturing tumor cells with conditional medium of NFs, the ability of migraton and invasion was decreased in tumor cells. Concomitantly, the epithelial marker of E-Cadherin was upregulated and the mesenchymal marker N-Cadherin was downregulated in tumor cells. In brief, NFs inhibit the EMT of tumor cells. Besides, β-catenin and DVL2 of Wnt/β-catenin signaling were downregulated by supernatant of NFs. Therefore, NFs suppressed the activation of Wnt/β-catenin signaling. Furthermore, NFs significantly upregulated the expression of Wnt5a of tumor cells concomitant with the activation of Wnt/Ca2+signaling.From the above findings, we can get the following conclusions:1. The degree of activation and senescence of human colorectal cancer associated fibroblasts is higher than that of normal colon fibroblasts;2. Human colorectal cancer associated fibroblasts promoted the cancer cells’EMT, migration and activated Wnt/β-catenin signaling in colorectal cancer cells.3. Human normal colon fibroblasts inhibited the cancer cells’EMT, migration, invasion and Wnt/β-catenin signaling in colorectal cancer cells, but promoted the proliferation, all of which is related with high expression of Wnt5a;4. The activation of Wnt/Ca2+ signaling pathway in tumor cells induced by human normal colon fibroblasts may be related with the high expression of Wnt5a. |
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