The Effect And Mechanism Of Resveratrol Potentiating The Activity Of Anti-tumor Drugs

Despite aggressive therapies, resistance of many tumors to current treatment protocols still constitutes a major problem in cancer chemotherapy. To potentiate the efficacy and decrease the resistance and side effect of antitumor drugs, drug combination is widely used clinically. Drug combination is an important progress in the treatment of cancer in recent years and has become the trend of cancer treatment.Resveratrol (RES), a plant produced anti-toxin, is a kind of non-flavonoid polyphenol, natural compound with anti-inflammatory, antioxidant, anti-tumor and some other bio-logical activity. Resveratrol has a very great value in anti-tumor and cardiovascular dis-ease.Gemcitabine (GEM) is a deoxycytidine analogue. It participates in DNA synthesis af-ter activation in the cell. Meanwhile, it inhibits the activity of ribonucleotide reductase and deoxycytidine deaminase. And it is a cell cycle specific anti-metabolic drug.In this study, we explored the effect of resveratrol on potentiating anti-tumor activity of gemcitabine in vivo and in vitro, and the molecular mechanism of the synergy with Gemcitabine. This research provides guidance for enhancing the anti-tumor effect and reducing the incidence of adverse reaction of gemcitabine clinically. Meanwhile, we studied the activity of resveratrol enhancing the anti-tumor effect of DNA damage drugs, and the anti-tumor effect of several new derivatives of resveratrol.1. The effect of RES on enhancing anti-tumor activity of GEM in vivo and in vitroWe explored the synergy of RES and GEM on 11 kinds of cell lines, including human normal cell lines, such as embryonic lung fibroblast cell line 2BS, human liver cell line L02, and human tumor cell lines, such as human hepatoma cell line HepG2 and Bel-7402, human non-small cell lung cancer cell line A549, human colon cancer cell line HCT116 (p53 wide type:wt, and p53 mutant:ko), human laryngeal carcinoma line KB and its drug resistant strain KBV, human cervical cancer cell line HeLa, mouse hepatoma cell line H22. We found that RES did not enhance the effect of GEM on inhibition in human normal cell lines, which means drug combination reduced the cytotoxicity of GEM to normal cells. Except for HeLa and HCT116 wt, RES combination with GEM had differ-ent levels of synergies on the other several tumor cell lines, in particular, the synergy of HepG2 cells was most significant with CI value of 0.52.Then we examined the synergic effect of RES combination with GEM on H22 tumor growth inhibition in mice. The results showed that RES(10mg/kg) combination with GEM at low dose (25mg/kg) and high dose (50mg/kg) had the CI value of 0.73 and 0.56 respectively, which means RES combination with GEM synergy is very significant in vivi.2. RES potentiates the effect of GEM on apoptosis induction in HepG2 cells.The results of heochst33258 stain,PI stain,western blot, showed RES enhanced the apoptosis induction activity of GEM in HepG2 cells.3. The molecular mechanism of the synergy of RES combination with GEMWe further studied the mechanism of synergy. The results showed that RES potentiate the inhibition effect of GEM in HepG2 cells in SIRT1-and p53-independent way, but it is associated with cell cycle S phase arrest and elevated levels of intracellular ROS; RES can reduce the expression of NF-κB and increase IκBαlevel in HepG2 cells; RES combination with GEM, reduced the downstream target proteins of NF-κB, including Survivin,Bcl-2,Bcl-xL,c-myc,Cyclin D1, while Bax level was promoted. The data indicated that RES enhance apoptosis induction activity of GEM in HepG2 cells and is associated with the inhibition of NF-κB signal pathway.4. Low dose combination of RES and GEM induces senescence-like phenotype occurred in HepG2 cells.We treated HepG2 cells with low dose of RES(10μM) and low doses of GEM(0.05,0.1μM) and found RES did not enhance the GEM-induced apoptosis in HepG2 cells, but led HepG2 cells senescence and growth arrest. Therefore, low dose RES also enhanced the inhibition effect of GEM on HepG2 cells growth.5. RES enhances the anti-tumor activity of DNA damage drugsWe also explored the synergy of RES combination with DNA damage drugs, including Bleomycin(BLM),Boanmycin(BAM),NC0604,Doxorubicin(DOX), in several tumor cell lines. The result showed RES can enhance anti-tumor activity of bleomycin family in a certain concentration range, but not significantly; however the synergy of RES and DOX combination was significant; RES combination with BAM,NC0604,DOX was synergic at a certain level in Bel-7402 cells, but antagonistic in HeLa cells with CI value greater than 1.RES (10mg/kg) combination with BAM (10mg/kg) on mice H22 tumor inhibition re-sults showed that, they were synergic with CI value of 0.73.At the same time we explored the anti-tumor activity of NC0604. The results showed DNA was damaged by NC0604 in HepG2 cells, and apoptosis was induced by NC0604 in HepG2 cells through regulating apoptosis associated proteins.6. The preliminary exploration of three resveratrol derivatives and the combination of anti-tumor.Resveratrol derivatives B1, B4, B5 showed different levels of growth inhibition in HepG2 cells. The anti-tumor effects of B1, B4 were stronger than RES significantly, de-serving further study. However, the results of B1,B5 combination with DNA damage drugs(BAM,NC0604,DOX) in HepG2 cells, were not satisfactory.This study showed that resveratrol as an anti-tumor sensitizer, has a great potential value in clinical therapy.