Carvacrol effect on topotecan cytotoxicity in various human cancer cells in vitro

Purpose: To investigate the modulatory effect of the natural phytochemical, carvacrol, on Topotecan (TOPO) cytotoxicity and cellular uptake in different cancer cell lines.

Methods: The cytotoxicity of the carvacrol/TOPO combination therapy was determined in vitro using crystal violet assay. Coomassie blue and DAPI fluorescent stains were used for cellular morphology and molecular cell death assessments, respectively. Additionally, TOPO cellular uptake after carvacrol/TOPO combination therapy was determined.

Results: Treatment of HeLa and HCT116 with carvacrol/TOPO resulted in 7.70- and 5.71-fold reduction in TOPO half maximal inhibitory concentration (IC₅₀), respectively, relative to TOPO single treatment. On the other hand, treatment of MCF-7, HepG2, SKOV3, and A549 cancer cells with carvacrol/TOPO resulted in increasing the IC₅₀ of TOPO by 1.49-, 1.33-, 1.50- and 1.26-fold, respectively, relative to TOPO single treatment.

Conclusion: Carvacrol had enhanced TOPO cytotoxicity and cellular uptake in HeLa and HCT116 cancer cells but might cause TOPO resistance in MCF-7, HepG2, SKOV3 and A549 cells.