Synergistic cytostatic effect of bleomycin with cisplatin on Hela cells.
Authors: Sitkovskaya Anastasia O. , Kit Oleg I. , Filippova Svetlana Yu , Mezhevova Irina V. , Gnennaya Nadezhda V. , Shamova Tatiana V. , Timofeeva Sofia V. , Novikova Inna A. , Menshenina Anna P. , Moiseenko Tatiana I. , Verenikina Ekaterina V. , Cherkasova Anna A. , Kruze Polina A. , Poryvaev Yuriy A. , Chernikova Natalia V. , Selezneva Olga G. , Adamyan Meri L. , Guskova Olga N. 
Published: June 2022

e15002 Background: Bleomycin is a glycopeptide antibiotic with anticancer properties. Clinical data indicate a relatively low efficacy of bleomycin in mono regimen, which is also accompanied by side effects from high doses. That’s why so it is more often used in relatively low doses in combination with other chemotherapy drugs. In particular, in cervical cancer, bleomycin is used in combination with cisplatin in a dose ratio of 0.8:1. Despite good clinical results, it is not known how the two drugs interact in vitro. The aim of this study was to evaluate the effect of combined application of bleomycin and cisplatin on HeLa cells. Methods: HeLa cells were seeded at 3000 cells per well in a 96-well plate (Eppendorf, Germany) and incubated for 24 hours in DMEM medium (Gibco, USA) supplemented with 10% FBS (HyClone, USA) at 37°C in an atmosphere containing 5.0% CO2. After 24 hours, the culture medium was replaced with a medium containing chemotherapy drugs in combination or as standalone agents in a series of two-fold dilutions: 0.03 - 32 µg/mL cisplatin and 0.012 – 12.8 µg/mL bleomycin. After 2 h exposition to studied compounds the medium was replaced and cells were incubated for another 72 hours. At the end of the experiment, the number of living cells was assessed using the MTT test. Viability was determined as the number of living cells in % of the control without the addition of chemotherapy drugs. Results: The combination of cisplatin with bleomycin demonstrated significantly greater efficacy than pure cisplatin in the concentration range from 0.03 µg/ml to 8 µg/ml, and pure bleomycin in the range of 0.012 - 12.8 µg/ml. The difference between the mean viability values for each concentration of pure bleomycin or pure cisplatin and their 0.8:1 mixture was significant at α = 0.05 (df = 14). Observed decrease in the viability of HeLa cells in comparison with pure substances is most pronounced in the range of non-toxic concentrations for both substances in mono regimen, namely 0.03 - 0.5 μg/ml for cisplatin, and at concentrations less than 0.125 μg/ml for bleomycin. Here, the increase in the difference between the dose-response curves grows as the concentration of the studied drugs increases. At cisplatin concentrations of 0.5–32 μg/ml, the difference in HeLa cell viability between pure cisplatin and its combination with bleomycin, on the contrary, decreases linearly with increasing cisplatin concentration, becoming insignificant above 16 μg/ml. Conclusions: The combined use of bleomycin and cisplatin on HeLa culture in a dose ratio of 0.8:1 exhibits synergistic properties that are most pronounced in the concentration ranges of both substances that do not have a cytotoxic effect in mono regimen.