Study On The Relationship Between SOCS2Expression And Platinum Resistance In Ovarian Carcinoma

Ovarian carcinoma comes first in gynecologic malignant tumor. Ovariancarcinoma may happen to women of any age,but the age group with a highincidence is between40and70years old. Its incidence covers22.9%of thegynecologic malignant tumor. At the same time, it is increasing every year at arate of1%,which is only after cervical carcinoma and endometrial carcinoma.Because the early stage of ovarian carcinoma shows no pathological signs andthere are no specificity screening methods towards early ovarian carcinoma,the patients only come to the hospital when the waist and abdominal painoccurs or when they have the digestive tract symptom. In this case,2/3ofthem are diagnosed at an advanced stage.At present, Paclitaxel andplatinum-containing chemotherapy is the main scheme for training advancedovarian carcinoma. But due to various reasons resulting in the primary andcompensatory drug resistance,the five-year survival rate of postoperativepatients is only20%～30%.To improve the cure rate of ovarian carcinoma, itis significant to seek for drug-resistance mechanism. And it has a profoundingmeaning in improving chemosensitivity,reversing drug resistance and modulating therapeutic scheme.In resent years, a kind of negativity regulatory protein depending oncytokine,the suppressor of cytokine signaling (SOCS) has been found. SOCSgives play to its biological function mainly by the feedback regulation towardsJAK/STAT signal transducer. JAK/STAT takes part in the transduction ofvarious cytokines,growth factor and hormone to realize the aim of modulatingthe cells’ growth, breeding, differentiation and apoptosis. In the past fewyears, it has been founded that JAK/STAT signal transducer participates in thetumor’s occurrence and spread.While SOCS restrains the abnormalproliferation of cells by feedback regulation towards the signal transducer tofacilitate cell apoptosis. This experiment probes into the relationship betweenSOCS2and platinum resistance in ovarian carcinoma by analyzingDDP-resistant human ovarian carcinoma cell A2780and the expression ofSOCS2in DDP-resistant human ovarian carcinoma cell CP70. At the sametime, it observes cell CP70’s changes towards the chemotherapy sensitivity ofcisplatin after protein expression increased.By using methylation specificity toinspect the methylation state of A2780and CP70cell receptor,at the sametime,by applying methylase to restrain the variation of SOCS2in the lattertwo ovarian carcinoma cells. And its sensibility of chemotherapeutic drugs.Probing into the possible functions of SOCS2in cells resistance in ovariancarcinoma and to offer evidences for the clinical value in reversing platinumresistance in ovarian carcinoma.Purpose1. To investigate the association between SOCS2expression and platinumresistance of ovarian carcinoma and the possible mechanisms.2. To investigate the change of SOCS2expression and their effect on platinum resistance after the treatment with methylase inhibitor.3. To investigate the change in platinum resistance of ovarian cancer cellswith increased expression of SOCS2caused by transient transfection andthe possible mechanisms.Materials and methods1. Real-time PCR, western blotting and immunocytochemistry assays wereused to detect the content of SOCS2mRNA, expression and location ofSOCS2protein in DDP-sensitive ovarian carcinoma cell line A2780andDDP-resistant human ovarian carcinoma cell CP70. The changes inSOCS2expression and location in A2780and CP70cell lines aftertreatment with DDP were analyzed by western blotting andimmunocytochemistry. And the association between SOCS2expressionand platinum resistance was also investigated.2. RT-PCR, western blotting and Immunocytochemistry assay were used todetect the expression of SOCS2in A2780and CP70cells treated withMethylase inhibitor5-Aza-CdR. MTT and TUNEL were used toinvestigate the effect of increased SOCS2expression on A2780and CP70cell apoptosis induced by Cisplatin.3. MTT assay was used to detect the change of the sensitivity to cisplatin inCP70cells with increased expression of SOCS2caused by transfectionwith pEGFP-N1-SOCS2; the change in cell apoptosis induced by cisplatinwas detected by TUNEL assay.Results1. SOCS2was expressed in cytoplasm in both A2780and CP70cells, andthe gene and protein expression was higher in A2780than in CP70.SOCS2expression in A2780and CP70cells treated with cisplatin decreased in a time and dose dependent manner.2. SOCS2expression in both cell lines increased in a dose dependent mannerafter been treated with different doses of methylase inhibitor,presenting the nucleoplasm expression status.3. The change of the sensitivity of CP70infected with pEGFP-N1-SOCS2tocisplatin.Conclusion1. SOCS2expression intensity was different in cisplatin-sensitiveand resistant cells and the expression of SOCS2decreased in a time-anddose-dependent manner in two ovarian cancer cells after been treated withcisplatin, suggesting an important role of SOCS2in the formation ofcisplatin-resistant mechanism in ovarian cancer.2. Low expression of SOCS2in A2780and CP70cells maybe associatedwith the CpG island methylation status in SOCS2promoter region. Afterdemethylation, SOCS2expression was significantly increased in both celllines and their sensitivity to DDP was also enhanced.3. the sensitivity of ovarian cancer cells to cisplatin and its mechanism maybe related to SOCS2mediated JAK/STAT pathway which inhibited theabnormal cell proliferation. SOCS2may be a new gene involved in thereversal the platinum-resistance.