Cancer-associated fibroblast (CAF) secretomes-induced epithelial-mesenchymal transition on HT-29 colorectal carcinoma cells associated with hepatocyte growth factor (HGF) signalling.

ABSTRACT

OBJECTIVE: The aim of this study was to investigate the effect of cancer-associated fibroblasts (CAF) secretomes on the epithelial-mesenchymal transition (EMT) of colorectal carcinoma (CRC) cells and its association with hepatocyte growth factor (HGF) signalling focussing on the HGF receptor, c-Mesenchymal epithelial transition (c-Met), and the EMT markers, vimentin and e-cadherin, in CRC cells. METHODS: Conditioned mediums (CM) containing secretomes from colorectal CAFs and their counterpart normal fibroblasts (NFs) of three CRC patients were collected and supplemented to the HT-29 CRC cells. The mRNA levels of a-smooth muscle actin (a-SMA) and HGF in both fibroblasts, as well as c-Met, vimentin, and e-cadherin in HT-29 cells after supplemented with CAF- and NF-CM were determined using quantitative reverse transcription-polymerase chain reaction (qRT-PCR). HGF protein level in the CM of CAFs and NFs was measured using enzyme-linked immunosorbent assay (ELISA). Vimentin and e-cadherin protein expressions were observed in HT-29 cells using immunofluorescent (IF) staining. RESULTS: Compared to the non-cancerous colon, fibroblasts from cancerous area of CRC substantially expressed higher mRNA levels of a-SMA, a CAF marker. The HGF mRNA expressions in CAFs and NFs were in line with the HGF protein level in the secretomes of both cells. CAF-CM increased c-Met and vimentin mRNA levels in HT-29 cells. Surprisingly, e-cadherin mRNA level in HT-29 cells was increased following CAF-CM supplementation. We also demonstrated the co-localization of e-cadherin and vimentin in the HT-29 cell cytoplasm. CONCLUSIONS: CAF secretomes of CRC promote a hybrid type of EMT associated with HGF signalling.