Pretreatment by tubulin agents decreases C-MYC induction in human colon carcinoma cell line HT29-D4.

For HT29-D4 cell line, we confirmed the interaction between c-Myc protein and microtubules by immunoprecipitation. We then studied the effect of antimitotic agents, nocodazole and the taxoids [paclitaxel (taxol) and docetaxel (taxotere)] on c-myc oncogene expression. The expression was analyzed by RT-PCR and Western blot. Taxol (1 microM), taxotere (1 microM) and nocodazole (3 microM) inhibited by 30-50% the c-myc induction produced by growth factors in culture medium. According to the flow cytometry analysis, the inhibition is not linked to the mitotic block. These results observed for both stabilizing and depolymerizing agents suggest that microtubular system is involved in c-myc expression more through its dynamic properties which influence signal transduction and intracellular transports than through its direct interaction with c-Myc protein.