The Role Of S100A4in Platinum Resistance Of Ovarian Cancer

THE BACKGROUND AND OBJECTIVESOvarian cancer is one of the most common malignant tumor of department ofgynecology, the epithelial ovarian cancer is one of the most common ovarian tumor and itsfatality rate is highest in gynecological tumors. Because ovarian has a special anatomicallocation, So patients who got the Ovarian cancer are often no obvious, insidious onset,lack of effective early diagnosis. At present, ideal cytoreductive surgery and neoadjuvantchemotherapy based on platinum are considered the standard for management of ovariancancer. Most patients can be sensitive to the first chemotherapy after surgery.But with thechemotherapy, the most patients beginmulti-drug resistance.So that the survival rate ofpatients with ovarian cancer do not improved significantly. However, many patients getthe drug-resistance which we can not control. So investigate the effective ways to reversethe platinum resistance in tumors will be beneficial to the large numbers of ovarian cancerpatients.S100A4(calcium-binding protein S100A4) is one of the important members of thecalcium-binding protein S100.Manystudies proved thatS100A4highly expresse in manycancers and related with tumor development, invasion and metastasis,and prognosis ofpatients.We speculated that S100A4has a good prospect in cancer gene treatment, it maybecome targets toreverse the drug-resistance. In previous experiments,we have beenconfirmed human ovarian cancer cell A2780which is sensitive to cisplatin showed lowexpression of S100A4, and CP70which is cisplatin-resistant showed high expression.we also find use the cisplatin to situmilate CP70cell, the expression of S100A4has a risingtrend with the extension of time.Therefor, we hypothesized that S100A4may be closelyassociated with ovarian cancer drug-resistance. This study by using the recombinantplasmid S100A4-pEGFP-N1and S100A4siRNA transfected A2780cells and CP70cells,than we observedthe expression of S100A4in mRNA and proteinlevels, detectionthe expression of S100A4how to infulent the biological function of ovarian cancercells.We inquiry to find S100A4the correlation with platinum-resistant in ovariancancer.We want to provide new ideas in ovarian cancer gene therapy.METHODS1. we divided the epithelial ovarian cancer patients into groups of platinum-resistantgrouo and platinum-sensitive group, using immunohistochemistry to find expressionof S100A4gene in epithelial ovarian cancer;2. Transfected the S100A4-pEGFP-N1and S100A4siRNA into A2780cells and CP70cells respectively. By qRT-PCR and Western Blot to detect the expression of S100A4in mRNA and protein levels;3. MTT method was used to describe A2780cells and CP70cells which were transfectedinto the recombinant plasmid S100A4-pEGFP-N1and S100A4siRNA the sensitivityof cisplatin;4. Apoptosis of the cisplatin-treated in transfected A2780cells and CP70cells wasexamined by AnnexinV/PI analysis using flow cytometry;5. Using the flow cytometry analysis to fing the effect of recombinant plasmidsS100A4-pEGFP-N1and S100A4siRNA on cell cycle in transfected A2780cells andCP70cells.6. Using the transwell to find the effect of recombinant plasmids S100A4-pEGFP-N1and S100A4siRNA in capability of invasion on transfected A2780cells and CP70cells.RESULTS1. The expression of S100A4was obviously higher than that of normal ovarian tissue in ovarian cancer, then we also found that S100A4high expression in ovarian cancer ofplatinum resistance groups,the proportion of nuclear expression is significantlyhigher than platinum sensitive group of patients (P <0.05).2. The use of qRT-PCR and Western Blot Show that recombinant plasmid S100A4-pEGFP-N1and S100A4siRNA effective increase the expression of S100A4inA2780cells and decrease the expression of S100A4in CP70cells, respectively.3. The transfection recombinant plasmid S100A4-pEGFP-N1, determined by MTTmethod to detect A2780cells after transfection of cisplatin sensitivity decreasedsignificantly (P <0.05), increase the expression of S100A4, A2780cells to cisplatinsensitivity fell by about2.69-fold.4. Transfection S100A4siRNA CP70cells sensitivity to cisplatin significantly enhanced(P <0.05), inhibit the expression of S100A4, CP70cells to cisplatin sensitivityincreased1.90-fold.5. S100A4pEGFP-N1transfection group compared with negative control group, cellapoptosis rate decline; SiRNA transfection group compared with negative controlgroup, apoptosis rate increased.6. Cell cycle analysis showed that the G1phase was decreased and S phase wereincreased in S100A4-pEGFP-N1transfected cells. On the other hand, S100A4siRNA transfected into CP70cells can make the S-phase decreased.7. By Transwell experiments, observation of S100A4pEGFP-N1transfection groupwith membrane cells was increased significantly (P <0.05), A2780cells willenhance cells capability of invasion markedly; S100A4siRNA transfection group ofmembrane cells was reduced significantly (P <0.05), CP70cells capability ofinvasion is reduced.CONCLUSIONIn this experiment, the study found that in the organization level of S100A4inovarian cancer takes the high expression of S100A4located in patients with ovariancancer cells within the platinum resistance. Using S100A4-pEGFP-N1recombinant plasmid and S100A4siRNA transfected to the ovarian cancer cells, then observed the effetof cell biological function, such as metastasis and invasion ability, apoptosis, cell cycleand platinum sensitivity. These results provided evidences for the important role ofS100A4on chemoresistance of ovarian cancer and give us a new target to reverse thechemoresistance.