| Objective:Ovarian cancer is a common malignant tumors of the femalegenital system, which ranks first in the mortality rate of all gynecologicmalignancies, has become a serious threat to woman’s lives and health.Epithelial ovarian cancer (EOC)is derived from the ovarian surface epithelium,is the most common ovarian cancer. The high mortality rate of ovarian canceris mainly due to concealment onset of ovarian cancer, the lack of specificsymptoms and signs early. the vast majority of ovarian cancers are diagnosedat advanced stages (stagesIII–IV), when tumors have already occurred pelvicand abdominal metastases. the prognosis is poor. If early ovarian cancerlesions confine within the envelope (Ⅰ s tage),the5-year survival rate ofpatients is90%. Currently, Cytoreductive surgery combined with postoperati-ve adjuvant platinum-based chemotherapy is the preferred treatment forovarian cancer. Although platinum-based initial chemotherapy is effective forabout70%to80%of ovarian cancer patients, the high rate of resistance tomake5-year survival rate is only20%to30%. So, what is the root cause ofovarian cancer drug resistance, which cytokines can inhibit or promoteoccurrence and development of tumor, This is a hot spot in the scholars now,but so far there is no breakthrough progress.In recent years, the research of stem cells promote the development ofoncology, because the growth characteristics of the tumor cells and stem cellshave many similarities, which contributed to the proposed "cancer stemcell(CSCs)" theory." Cancer stem cells" refers to a class of cells with stem cellproperties in the tumor tissue. Although it is only a small subset of cancercells, they behave in ways that are analogous to normal stem cells. Cancerstem cells were first discovered in leukemia. followed by breast cancer,prostate cancer, lung cancer and other tumors, cancer stem cells were found. Studies have proved they maybe the key to tumor tumorigen, relapse and drugresistance.Stem cell characteristics of cancer stem cells make us believe thatsignaling pathways regulating the biological behavior of normal stem cellshould also be applied to CSCs. OCT4, NANOG, KLF4and SOX2is the mainsignaling molecules to maintain the stem cell self-renewal, pluripotency andunlimited proliferation.Octamer4(OCT4) is a member of POU transcriptionfactor family, which show a high expression in embryonic stem cells, adultstem cells and cancer stem cells. Over expression of OCT4can maintainself-renewal, unlimited proliferation and pluripotency of embryonic stem cell.Small RNA interference (siRNA) suppress OCT4expression, which caninduce cancer stem cell apoptosis and significantly inhibit tumor growth.Studies have shown that OCT4in Ishikawa endometrial cancer cell linesshowed high expression and the expression level of OCT4in poorlydifferentiated endometrial carcinoma was higher than well-differentiatedcarcinoma. OCT4was negatively correlated with tumor grade. Thus, weenvisage drug resistance of epithelial ovarian cancer may be associated withthe high expression of OCT4.In this study, we cultured cancer cell and establish transplantation tumormodel in nude mice, to study OCT4expression in resistant and non-resistantovarian cancer cell lines and transplantation tumor and explore the role ofOCT4in drug resistance epithelial ovarian cancer.Methods:1Cell culture: ovarian serous papillary adenocarcinoma cell line SKOV3weremaintained in RPMI-1640, containing10%fetal bovine serum (FBS) at37℃,5%CO2, humidified incubator culture.2The establishment of the nude mouse model: In this study,Non-drug-resistant human ovarian serous adenocarcinoma cell line SKOV3,and cisplatin-resistant human epithelial ovarian cancer cell Line SKOV3/DDPwere conventionally cultured. we collected cancer cell until the cells growingto80%-90%of bottle bottom.when the cells were sufficiently dispersed, counted and made single cell suspension at a density of5×107/ml. Thesuspension (about1×107cells per nude in0.2ml suspension) was inoculatedat subcutaneous of the nude mouse’s dorsal near hindlimb in sterile conditions.After10days of inoculation, chose the successful model with transplantedtumor about5~8mm in diameter. the part immediately was put in liquidnitrogen, spare part was made of a single cell suspension to prepare for flowcytometry.3The OCT4protein was detected by flow cytometry technology in cellularlevel and transplanted tumor tissue.4The transplanted tumor tissues and cancer cell which were stored at liquidnitrogen tank and without reagents fixed were taken and detected theexpression of mRNA-OCT4by RT-qPCR technology.5The statistical method: SPSS17.0statistical software processing of theexperimental data. Measurement data was analyzed by two independentsamples t test analysis of mean comparison, with P<0.05for the differencewas statistically significant.Results:1In vitro, compared with non-resistant cell lines SKOV3, the level of OCT4mRNA and protein was overexpressed in resistant SKOV3/DDP cells, andalmost92.8%cells expressed OCT4antibody compared with isotype antibody(iso) staining in flow cytometry, but the SKOV3cells expression rates were52.9%in flow cytometry, with a statistically significant difference.2In vivo xenograft model, the expression of OCT4was about3.7%inestablished SKOV3/DDP tumor model analyzed by flow cytometry, and onlyabout2.5%cells were OCT4-positive cells in established SKOV3tumormodel. At the same time, applying real-time PCR technology to detectmRNA-OCT4expression in established tumor tissue, we found the relativelevel of OCT4mRNA was more expressed in the established SKOV3/DDPtumors compared with established SKOV3tumors, with a statisticallysignificant difference. Conclusions:Compared with the SKOV3cells and established SKOV3tumor, it wasin the study found that the level of OCT4was higher expressed in theSKOV3/DDP cells and established SKOV3/DDP tumor, suggesting thatresistance serous epithelial ovarian cancer may be associated with highexpression of OCT4. |
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