Research Of Interactive Effects Between GLN And 5-Fluorouracil,Epirubicin,Mitomycin C,Oxaliplatin And The Mechanism Of These Effects On Human Gastric Carcinoma Cell Strain MGC-803

Objective: To investigate the interactive effects between Glutiamine(GLN)and 5-Fluorouracil(5-Fu),Epirubicin(EPI),Mitomycin C(MMC),Oxaliplatin(L-OHP) and the Mechanism of the these effects on Human GastricCarcinoma Cell strain MGC-803. To explore the rational way of using GLN andchemotherapy drugs effectively and correctly in patients with gastric cancer.Methods: Anti-cancer effects of chemotherapeutic agents and GLN was testedby MTT assay, and the interactive effects between chemotherapeutic agents andGLN were evaluated by Chou-Talalay combination index equation(i.e.median-effect principle). Flow cytometer was used for cell cycle anlalysis. Theultrastructural changes of cancer cells were observed by transmission electronmicroscope. The apoptotic change of cells was observed by Hoechst 33258staining fluorescence microscopy assay, and the apoptotic rate was detected byAnnexinⅤ/PI double staining flow cytometry. The protein level of Bcl-2,NF-κB,VEGF was determined by Western blot analysis.Results:1. GLN doesn't stimulates cell growth obviously in vitro.High-concentration GLN itself may act as a cell grow inhibitor.2. The anti-cancer activity of MMC is in a time-dependent manner. Thecombination of GLN and MMC results in weak antagonistic cytotoxic effects(1.01＜CI＜1.29). MMC induces remarkable S-phase arrest and enhances the proliferation index(PI) of MGC-803 cell. GLN, especially high-dose GLN, canattenuated the S-phase arrest and low the PI induced by MMC. GLN canaggravate ultrasturctural damage and increase apoptosis caused by MMC.GLN can enhance the chemo-sensitiveness and reverse chemo-resistancethrough down-regulating NF-κB protein expression level.3. The anti-cancer activity of 5-Fu is in a time-dependent manner. It isrational to combine 5-Fu and GLN in high dose because high-dose combinationof them results in synergistic cytotoxic effects and low-dose combination resultsin antagonistic cytotoxic effects. 5-Fu used alone or combining with GLN canhardly influence cell cycle distribution and the PI. GLN can aggravateultrasturctural damage and increase cytonecrosis caused by 5-Fu. GLN canenhance the chemo-sensitiveness and reverse chemo-resistance throughdown-regulating NF-κB and VEGF protein expression level.4.The anti-cancer activity of EPI is both in time-dependent manner and indose-dependent manner. There is a synergistic interaction between them whencombining them in low-dose and a antagonistic interaction when in high-dose.EPI shows G2/M-phase and S-phase arrest due to the different concentration andtime. GLN, especially high-dose GLN can low the PI enhanced by EPI. GLNcan aggravate ultrasturctural damage and increase apoptosis caused by EPI.GLN can enhance the chemo-sensitiveness and reverse chemo-resistancethrough down-regulating NF-κB,VEGF protein expression level.5. The anti-cancer activity of L-OHP is both in time-dependent manner andin dose-dependent manner. Try to avoid combining them in high concentrationbecause there is a remarkably antagonistic interaction between them whencombining in high-dose. However, low-dose combination of them results in synergistic cytotoxic effects, low-dose L-OHP inducing both S-phase andG2/M-phase arrest, middle-dose L-OHP inducing remarkable S-phase arrest,high-phase inducing none arrest. Low-dose and middle-dose L-OHP increase thePI obviously, and high-dose L-OHP does not. GLN can aggravate ultrasturcturaldamage and increase apoptosis caused by L-OHP. GLN can enhance thechemo-sensitiveness and reverse chemo-resistance through down-regulatingNF-κB,VEGF protein expression level.Conclusion:1. GLN is safe to be applied to patients of cancer, because Glutamine doesn'tstimulates cells growth obviously;2. GLN can be applied combining with MMC because GLN can enhance thecytotoxic effects of MMC and decrease the PI.3.The combining dose of GLN and 5-Fu shouldn't be too low, in which wecan get synergistic cytotoxic effects.4. The combining dose of GLN and EPI shouldn't be too high, in which wecan not only get synergistic cytotoxic effects but also increase apoptosis rate,low the PI, and aggravate cellular damage.5. The combining dose of GLN and L-OHP shouldn't be too high, in whichwe can not only get synergistic cytotoxic effects but also can increase apoptosisrate, aggravate cellular damage.6.All the four chemotherapeutic agents can increase the NF-κB proteinexpression level, and GLN may enhance the chemo-sensitiveness and reversechemo-resistance through down-rugulate the NF-κB protein expression level.