[Colorectal cancer cells induce the formation of cancer-associated fibroblasts by activating the ERK signaling pathway in fibroblasts]

OBJECTIVE

To investigate the mechanism by which conditioned medium of colorectal cancer cells promotes the formation of cancer-associated fibroblasts (CAFs).

METHODS

Normal human colorectal fibroblasts (CCD-18Co cells) in logarithmic growth phase were treated with the conditioned media of colorectal cancer HCT116 cells (HCT116-CM) or Caco-2 cells (Caco-2-CM) alone or in combination with 300 nmol/L ERK inhibitor SCH772984. The expression levels of CAFs-related molecular markers were detected in the treated cells with real-time quantitative PCR (RT- qPCR) and immunofluorescence assay, and the changes in cell proliferation, colony formation and migration were assessed with RTCA, colony formation and wound healing assays; Western blotting was performed to detect the activated signaling pathways in the fibroblasts and the changes in CAFs formation after blocking of the signaling pathway.

RESULTS

HCT116-CM and Caco-2-CM significantly upregulated mRNA expression levels of CAFs markers (including α-SMA, FAP, FN and TGF-β) in CCD-18Co cells, and strongly promoted fibroblast transformation into CAFs (P < 0.05). The two conditioned media also promoted the proliferation, colony formation and migration of CCD-18Co cells (P < 0.05) and significantly increased the levels of α-SMA protein and ERK phosphorylation in the cells (P < 0.05). The ERK inhibitor SCH772984 obviously inhibited the expression of α-SMA and the transformation of CCD-18Co cells into CAFs induced by the conditioned medium of colorectal cancer cells (P < 0.05).

CONCLUSION

Colorectal cancer cells may induce the formation of colorectal CAFs by activating the ERK pathway in the fibroblasts.

Variability of posterior veins of the left ventricle in the adult human heart

The frequency of occurrence and topography of the outfow portions of the posterior veins of the left ventricle were observed. One hundred fifty adult human hearts of both sexes from l8 to 85 years of age fixed in a formalin/ethanol solution were examined. Classical macroscopic anatomical examination methods were used. The posterior veins of the left ventricle were always present in the examined heart material, but occurred in varying number (l -4). The outfow portions of these veins were characterized by significant variation with regards to position as well as angle of its outfow.