Caveolin expression and regulation in colorectal cancer cell lines

Abstract

The basal level of caveolin-1 in colorectal carcinoma cells was studied and it was found that different cell lines express different basal amounts of the protein. The relationships between caveolin-1 and proteins such as p53, p42/44 MAP kinase, and COX-2 in human colorectal cancer cell lines were studied using RT-PCR and Western Blot techniques. I found that NO down-regulated caveolin-1 and that plating density had no effect on the level of basal caveolin-1. Proteosomal inhibitors, ALLN and lactacystin, were tested on the cell lines and protein and mRNA levels were studied to elucidate the role of the proteosomal pathway in both the transcriptional and translational pathways of caveolin-1 regulation. Results indicate that ALLN, when used together with NO, downregulates caveolin-1 at the transcriptional stage. p42/44 MAP kinase up-regulated caveolin-1 levels and caveolin-1 was also regulated by p53. HCT116 cells were transfected with mutant p53 plasmids, pCep4 and pXJHA, and results indicated that mutant p53 downregulated caveolin-1 levels. HCA7 cells which were transfected with pCI-Cav-1 (vector with the human caveolin-1 gene incorporated) helped establish a link between COX-2 and caveolin-1. Preliminary experiments indicate that COX-2 is downregulated by caveolin-1. The reverse may be true as well but further studies are needed. Patient cDNA samples were also analyzed for caveolin-1 expression. The results were inconclusive possibly due to the small sample size.