Resveratrol enhances the cytotoxic profile of docetaxel and doxorubicin in solid tumour cell lines in vitro

Abstract

Objectives: Resveratrol, with its robust antioxidant activity, has frequently been suggested as potentially having activity in cancer prevention and some recent reports have indicated that it has cancer treatment potential for several types of neoplasia. It has been found to block p-glycoprotein and to protect against several chemotherapeutic agents' side effects. In this study, we assessed interactive characteristics of resveratrol with docetaxel and doxorubicin and further investigated molecular bases of this interaction in cells of three different solid tumour lines (MCF-7, HeLa and HepG2).

Materials and methods and results: Resveratrol per se was found to have anti-cancer properties, but with relatively low potency in all tested cell lines (IC(50) ranged from 35.1 to 83.8 μM). Doxorubicin and docetaxel showed IC(50) ranging from 0.48 to 0.72 μM and from 25.9 to 77.8 nM, respectively. Resveratrol in combination with doxorubicin and docetaxel significantly increased potencies of both chemotherapeutic agents showing IC(50) ranging from 0.12 to 0.34 μM and from 7.2 to 53.02 nM, respectively. The combination index showed synergistic interaction between resveratrol and doxorubicin or docetaxel on MCF-7 cells, and additive interactions on HeLa and HepG2 cells. Real time PCR revealed that expression of Bax and Bcl-2 was simultaneously elevated on combination of resveratrol with doxorubicin or docetaxel in all tested cell lines, whereas p53 exhibited marginal elevation in MCF-7 and HepG2 cells. In addition, p-glycoprotein efflux activity was significantly inhibited, with subsequent accumulation of p-glycoprotein substrate in intracellular compartments. Expression level of mdr1 gene was downregulated after resveratrol combined with doxorubicin or docetaxel in all tested cell lines.

Conclusion: Resveratrol potentiates cytotoxic properties of both cancer drugs used in the study through increasing their intracellular level due to p-glycoprotein inhibition and downregulation of mdr1 gene.

Figure 1

Effect of resveratrol (RES) on dose–response curve of docetaxel (DCX) (a) and doxorubicin (DOX) (b) on MCF‐7 breast cancer cells, was assessed. Cells were exposed to serial dilution of DCX/DOX (•), RES (○) or combination of RES with DCX/DOX () for 72 h. Cell viability was determined using SRB‐U assay; data are expressed as mean ± SD (n = 3).

Figure 2

Effect of resveratrol (RES) on dose–response curve of docetaxel (DCX) (a) and doxorubicin (DOX) (b) on HeLa cervical cancer cells was assessed. Cells were exposed to serial dilution of DCX/DOX (•), RES (○) or combination of RES with DCX/DOX () for 72 h. Cell viability was determined using SRB‐U assay; data are expressed as mean ± SD (n = 3).

Figure 3

Effect of resveratrol (RES) on dose–response curve of docetaxel (DCX) (a) and doxorubicin (DOX) (b) on HepG2 liver cancer cells was assessed. Cells were exposed to serial dilution of DCX/DOX (•), RES (○) or combination of RES with DCX/DOX () for 72 h. Cell viability was determined using SRB‐U assay; data are expressed as mean ± SD (n = 3).

Figure 4

Effect of resveratrol (RES) on apoptotic pathway in docetaxel (DCX) and doxorubicin (DOX)‐treated cells. Gene expression of BAX, Bcl‐2 and p53 using RT‐PCR on MCF‐7 (a and b), HeLa (c and d) and HepG2 (e and f) cells after treatment with DCX, DOX, RES or their combinations, was assessed. Data expressed as mean ± SD (n = 3).

Figure 5

Effect of resveratrol (RES) on apoptotic effective caspase‐3 on docetaxel (DCX)‐ and doxorubicin (DOX)‐treated cells. Caspase‐3 activity was assessed on MCF‐7, HeLa and HepG₂ cells after treatment with DCX, DOX, RES or their combinations. Data expressed as mean ± SD (n = 3).

Figure 6

Effect of resveratrol (RES) on expression of ABC‐binding cassette in docetaxel (DCX)‐ and doxorubicin (DOX)‐treated cells. Gene expression of mdr1 using RT‐PCR on MCF‐7 (a), HeLa (b) and HepG2 (c) cells after treatment with DCX, DOX, RES or their combinations was assessed. Expression relative to control group (d). Data expressed as mean ± SD. (n = 3).

Figure 7

Effect of resveratrol (RES) on efflux pumping activity of P‐gp. Intracellular concentration of P‐gp probe, doxorubicin (DOX), was assessed on MCF‐7 (a), HeLa (b) and HepG2 (c) cells after treatment with RES and VER for 1 hour. Data expressed as mean ± SD (n = 3).