Transforming growth factor‐β1 modulates metalloproteinase‐2 and ‐9, nitric oxide,RhoA and α‐smooth muscle actin expression in colon adenocarcinoma cells

Colon carcinoma invasiveness is a process involving cell–cell and cell–matrix alterations, local proteolysis of the ECM (extracellular matrix) or changes in cytokine and growth factor levels. In order to evaluate the role of TGF‐β1 (transforming growth factor‐β1) and small G protein RhoA in tumour progression, the influence of TGF‐β1 treatment or RhoA‐associated kinase inhibitor on the production of NO (nitric oxide) and MMP‐2 and MMP‐9 (metalloproteinases‐2 and ‐9) was analysed in three human colon adenocarcinoma cell lines (HT29, LS180, SW948) representing different stages of tumour development. All the tested cell lines produced low amounts of MMP‐2 and MMP‐9. rhTGF‐β1 and the synthetic Rho kinase inhibitor (Y‐27632) decreased MMP‐2 secretion by colon cancer cells, especially in the most advanced stage of colon cancer. rhTGF‐β1 decreased NO secretion by cells, while Y‐27632 had no effect on it. Immunoblotting with anti‐RhoA antibodies followed by densitometry revealed that RhoA levels were slightly increased after incubation of colon carcinoma cells (SW948) with rhTGF‐β1. rhTGF‐β1 induced α‐smooth muscle actin (α‐SMA) expression, especially in high Duke's grade of colon cancer, while Y‐27632 blocked it. Summing up, in colon carcinoma cells, TGF‐β1 and RhoA protein may regulate tumour invasiveness measured as MMP, NO and α‐SMA expression or assayed using motility data and may be a good target for cancer therapy.