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

Abstract

Abstract. 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.

Cleavage of bleomycin hydrolase by caspase-3 during apoptosis

“…The patients with homozygous variant G/G of BLH gene SNP (A1450G) are associated with reduced survival in testicular germ cell cancer (16). The expression of BLH increased after exposure to low concentrations of bleomycin (13). All data indicate that the BLH level plays an important roles in bleomycin action.…”

“…Western blotting. The method was performed according to the protocol previously published (13). The sources of primary antibodies were as follows: rabbit-anti-cleaved/total PARP-1 (9532), rabbit-anti-cleaved caspase-3 (9661) and cleaved caspase-9 (9501), all from Cell Signaling Technology, Inc. (Danvers, MA, USA).…”

“…For example, BLH is expressed at high levels in human tissues except for the kidneys and lungs (11,12). We recently demonstrated that BLH serves as a biomarker for predicting the efficacy of treatment of tumors with BLM (13).…”

“…The level of BLH in tumor cells affects the efficacy of BLM (13)(14)(15)(16). Therefore, it is necessary to understand how BLH is regulated to facilitate the development of new antibiotics structurally related to BLM and to demonstrate the pathological roles in the diseases.…”

Resistance to Bleomycin in Cancer Cell Lines Is Characterized by Prolonged Doubling Time, Reduced DNA Damage and Evasion of G2/M Arrest and Apoptosis

“…This may be due to reduced cellular uptake of BLM, and/or enhanced BLM elimination/detoxification, mediated by cell surface receptors or transporters [31], antioxidant molecules/enzymes that reduce BLM-generated ROS [11,32]; or enzymes that inactivate BLM [33,34]. Future studies need to further study these mechanisms.…”