Growth inhibition of human colorectal carcinoma cell lines by tumor necrosis factor-alpha correlates with reduced activity of pp60c-src.
One molecular alteration that has been observed in the majority of colorectal carcinomas is the activation of pp60c-src kinase. To address the role of pp60c-src in growth control of colon carcinoma cell lines, the effects of the biologic response modifier, tumor necrosis factor (TNF)-alpha were studied on the established HT29 colorectal carcinoma cell line and two clonal variants derived from the parental line. In one clone, HT29-A34, approximately 55% growth inhibition was observed following a 120-h incubation period with 10(3) U/ml TNF. In this TNF-sensitive cell line, pp60c-src immune complex kinase activity was reduced 3.9-fold accompanied by only a slight reduction in pp60c-src protein levels. Growth inhibition and decreased pp60c-src kinase activity correlated in a dose-dependent manner. The HT29-A14 TNF-resistant clone was not growth-inhibited by TNF, and no changes in pp60c-src were observed following treatment. Growth inhibition also correlated with reduced pp60c-src kinase specific activity in a number of other established colon carcinoma cell lines that were TNF-sensitive. In TNF-resistant colon carcinoma cell lines, pp60c-src kinase activity and levels remained unchanged. When changes in specific activity of pp60c-src were observed in sensitive cells, they occurred after decreased [3H]-thymidine uptake was observed. Therefore, these changes in pp60c-src activity are not the earliest event in TNF-induced growth inhibition. Nevertheless, our results suggest that modulation of pp60c-src kinase activity may be important in growth control of colorectal carcinoma cell lines.
Novotny-Smith
C L
CL
Department of Tumor Biology, M.D. Anderson Cancer Center, University of Texas, Houston 77030.
Gallick
G E
GE
D000230:Adenocarcinoma / Q000473:pathology*; D002455:Cell Division / Q000187:drug effects; D015179:Colorectal Neoplasms / Q000473:pathology*; D004261:DNA Replication / Q000187:drug effects; D006801:Humans; D007700:Kinetics; D009363:Neoplasm Proteins / Q000032:analysis*; D016392:Proto-Oncogene Proteins pp60(c-src) / Q000032:analysis*; D014407:Tumor Cells, Cultured / Q000187:drug effects; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
D009363:Neoplasm Proteins; D014409:Tumor Necrosis Factor-alpha; D016392:Proto-Oncogene Proteins pp60(c-src)