Action of bleomycin is affected by bleomycin hydrolase but not by caveolin-1.

Bleomycin is a first-line clinically used antitumor antibiotic for effective treatment of certain types of cancer in combination with other antitumor agents. Its action is affected by bleomycin hydrolase (BLH), DNA repair enzymes, membrane transport proteins and other cellular factors. To clarify whether BLH confers the resistance to bleomycin in tumor cells, it is necessary to further investigate the roles of BLH and its combination with other factors such as caveolin-1 in the action of bleomycin. In this study fourteen human cell lines were used for determination of bleomycin action and roles of BLH and caveolin-1. The relationship between action of bleomycin and cellular amount of BLH was detected by the MTT method and western blotting in the human leukemia cell line HL-60, HeLa cervical cancer cells and HaCaT immortalized keratinocyte cells. The sensitivity to bleomycin was increased in HeLa cells after knockdown of BLH mRNA by RNA interference. There is no relationship between caveolin-1 levels and action of bleomycin, although the distribution of the cell cycle was altered in the caveolin-1-knockdown HeLa cells after treatment with bleomycin. In addition, regulation of BLH and caveolin-1 expression in HeLa and HaCaT cells was observed in a concentration-dependent manner after exposure to bleomycin. In conclusion, bleomycin hydrolase is one of the biomarkers for determination of bleomycin action. Although caveolin-1 can respond to bleomycin treatment, it is unrelated to bleomycin sensitivity.