The molecular mechanisms underlying the transformation of normal fibroblasts into cancer-associated fibroblasts promoting the neoplastic process remain elusive. An attractive possibility is that subversive signals from cancer cells alter the epigenomic profile of normal fibroblasts reprogramming them to serve as partners in crime with an altered but stable phenotype. To test this tenable hypothesis human colonic fibroblasts (CCD-18Co cell line} and human colonic cancer cells (HT-29 cell line) were co-cultured for 24, 48 and 72 h in a Transwell system preventing direct cell-to-cell contact but allowing paracrine communication. Each cell line cultured separately served as the appropriate control.
At the end of the selected culture time periods genomic DNA was extracted and levels of 5-methyl cytosine were determined using a microplate-based ELISA. The findings indicate that co-culture for 72 h of CCD -18Co cells with HT-29 cells resulted in marked global DNA hypomethylation of fibroblasts. Putative molecular changes provoked in fibroblasts by DNA hypomethylation ,such as the induction
of cyclooxygenase-2 and fibroblast-activation protein expression, are under investigation.
A concomitant research is focused on the characterization of the epigenetic profile of human stromal colonic fibroblasts harvested from tissue specimens of normal individuals and of patients at various stages of sporadic colorectal cancer.
