The Effect And Mechanism Of Gomisin A In Enhancing Inhibition Of Paclitaxel By Decreasing ROS On Ovarian Cancer Cell Skov3

Background: The mortality rate of ovarian cancer lives first in gynecological tumors.Because the early symptoms are not typical, the patients are often already in an advanceddisease stage when they see a doctor. Poor prognosis and high mortality make patients beafraid of it. Currently treatments are mainly ovary tumor rebulking operation and adjuvantchemotherapy with paclitaxel and carboplatin after the operation. However, the adverseeffects of chemotherapy drugs and drug resistance have been followed clinically. How toreduce the adverse effects of drugs, make drug resistance lower and enhance the anti-tumoreffects becomes the focus of research interest.Fructus Schizandra is commonly used in traditional Chinese medicine, because of itsprotection wih heart and kidney and high medicinal value. Previous studies have found thatthe active constituents of the Schisandra crude extracts could reverse multidrug resistanceto increase the chemotherapeutic drug sensitivity of tumor cells by inhibiting theexpression of P-gp and PKC[1].Reactive oxygen species (ROS) is the active chemical nature of the oxygen atom orgroup of atoms with a strong oxidizing ability[2]which plays an important role in the innateimmune regulation. But an excess of ROS could mediate oxidative stress to causeirreversible cell damage, leading to cell death eventually[3]. The mutations of MitochondrialDNA lead to increased ROS production, followed by further mutations of mtDNA andadditional increases of ROS, thereby create oxidative stress, which could favor the processof carcinogenesis[4]. As a thiol antioxidant, N-acetylcysteine (NAC) which goes throughcell membranes easily is a ROS inhibitor to affect the intracellular redox state significantlyto reduce the occurrence of oxidative damage[5].Purpose：Investigating the change of ROS activity after Gomisin A in combinationwith paclitaxel works on ovarian cancer cells Skov3, we discuss the mechanism of GomisinA in enhancing chemosensitivity of paclitaxel by ROS. Method: In this study, we apply in vitro culture of human ovarian cancer cell Skov3,and set up different groups giving GA with or without paclitaxel, or giving NAC with orwithout paclitaxel for6hours. We use MTT assay to check the cell proliferation inhibitionrate out. Flow cytometry instrument detects cell apoptosis rate, cell cycle and the level ofROS by Dichlorofluorescin diacetate (DCFH-DA). Western blot detects the expression ofcell cycle-related proteins, including CDK4, CyclinB1and P53.Result: The experimental results showed that Gomisin A could enhance the sensitivityof PTX chemotherapy when combined on Skov3cells, inhibiting cell proliferationsynergistically. With flow cytometry instrument detecting the number of cell apoptosis, cellcycle and the lever of ROS, we found that Gomisin A had an antitumor effectsynergistically with paclitaxel by reducing the level of ROS and inhibiting the cell cycle.The results of Western blotting showed that Gomisin A and PTX could respectivelydecrease protein expression levels of CDK4, CyclinB1and P53, and when combined witheach other, the alteration of protein expression is more obvious. Using NAC with PTX, wecould draw the same results as GA, further confirm that by reducing the lever of ROS, GAcould enhance the sensitivity of PTX in the proliferation of ovarian cancer cells Skov3.Conclusion: The study results suggest that GA combined paclitaxel on ovarian cancerSkov3cells could inhibit the cell cycle, increase the sensitivity of paclitaxel to tumor cellsand induce the anti-cancer effect of the drug. Its molecular mechanisms may be to decreasethe level of ROS in Skov3cells and regulating the expression level of cell cycle proteinsCDK4, CyclinB1and P53to inhibit cell cycle progression.