SRC transcriptional activation in a subset of human colon cancer cell lines

Human Src encodes the non-receptor tyrosine kinase pp60(c-Src), which is activated in many human colon Cancer cell lines (HCCLs) and tumors. We found that both c-Src protein and mRNA levels were elevated in a subset of HCCLs. Increased c-Src mRNA and protein levels correlated strongly with increased c-Src kinase activity. Nuclear run-on analysis and c-Src mRNA half-life determination demonstrated increased mRNA levels were due to increased transcription of the Src gene. We also observed decreased c-Src mRNA stability in cell lines that displayed Src transcriptional activation. Our findings provide the first evidence that Src transcriptional activation is an important determinant of c-Src expression and activity in HCCLs.