1.Serum Microrna Expression Profiling Serves As Diagnositic Biomarkers 2.Research On ZEB1 And Target Genes Of Chemotherapeutic Resistance To Breast Cancer

GLOBOCAN estimates that breast cancer is the most frequent cancer in women in China and abroad. With the increasing attention of the breast health, new method for early detection of breast cancer need to be developed urgently. Sensitivity and specificity are the main bottleneck in tranditional biomarkers. Micro RNA(mi RNA) has been reported to be presented in human blood and has been increasingly suggested as a biomarker for diseases. In this study, we sought to identify some new serum mi RNAs suitable for diagnosis of early breast cancer.mi RNAs are a large class of small, regulatory noncoding RNAs in plants and animals that inhibit gene expression by binding to imperfect complementary sites within the 3’UTR of their target gene. Having the advantages of stablility and easily obtaining, mi RNAs are emerging as promising sensitive and specific biomarkers for early detection of cancer.A multiphase, case-control study was designed to identify serum mi RNAs as surrogate markers for breast cancer. In this study, we collected92 patients with primary breast cancer, 100 benign patients and 100 health control in our study. We further divided the samples into two subgroups which encluded lymph node metastasis v.s. lymph node non-metastasis and breast carcinoma in situ v.s. invasive breast cancer. The mi RNA expression profile of breast cancer from patients and matched benign and normal donors as well as the subgroup samples was determined by Affymetrixmicroarray followed by RT-PCR assay which uses a Taqman probe to systematically and comprehensively evaluate mi RNA concentrations in sera.The Affymetrix analysis demonstrated 11 markedly altered mi RNAs in patients groups, after being mergered in three subgroups. RT-q PCR analysis identified 3 mi RNAs. Among them, mi R-455-3p is markedly decreased in lymph node metastasis and invasive breast cancer groups and increased in lymph node non-metastasis and breast carcinoma in situ.Mi R-1915-3p and mi R-1825 are markedly decreased in lymph node non-metastasis and breast carcinoma in situ groups and increased in lymph node metastasis and invasive breast cancer. After the validation set, we elucidated mi R-455-3p as biological markers for breast cancer early detection. Besides,mi R-1825 and mi R-1915-3p are serum biomarkers for metastasis of breast cancer. The area under the receiver operating characteristic curve(AUC) for mi R-455-3p ranged from 0.5281 to 0.8831.For mi R-455-3p showing the best specility and sensitiviry, we chose it for the further experiment. Using mi RNA target prediction algorithms and reported assays, we demonstrated that mi R-455-3p suppressed the expression of PIK3 CA both at the m RNA and protein levels, and was directly bound to the 3’UTR of PIK3 CA m RNA. Taken together, our findings indicated that mi R-455-3p functions as tumor suppressor and biomarker for early detection for breast cancer, and the mi R-455-3p/PIK3 CA axis might represent a potential therapeutic target for breast cancer.Breast cancer is one of the most common cancer in women. With the development of the society and the change of reproductive and hormone factors, the incidence of breast cancer continues to increase year by year and is going to be the highest in China and abroad.For breast cancer treatment, adjuvant chemotherapy is a principal systemic treatment. But the intrinsic and acquired resistance to chemotherapy are the major obstacles for improving cancer patient survival.Therefore, it is necessary to elucidate the underlying mechanism of chemotherapy resistance of patients with breast cancer. The primary mechanism of genotoxic drugs is to interfere with enzymes involved in DNA replication. These drugs can also induce DNA intercalation and damage, which ultimately results in DNA lesions in the forms of double-stranded breaks(DSBs). The cellular response to DNA damage,known as the DNA damage response(DDR), involves the recognition of DNA damage, the activation of cell cycle checkpoints, transcription programs, DNA damage repair, and apoptosis. Over the past years,increasing evidences have demonstrated that ZEB1 acts as a driver of epithelial to mesenchymal transition(EMT) and cancer progression.Additionally, ZEB1 is linked to a chemoresistant phenotype in cancer cells.But the mechanism is still not fully understood. So in this experiment, wefocused to identify the role of ZEB1 in chemoresistance and DNA damage response.In order to explore the correlation between ZEB1 and different molecular subtype of breast cancer, we firstly tested the expression of ZEB1 in different breast cancer cell lines, and found the relation between ZEB1 expression and the molecular classification. Then we established the ZEB1-OV/KD cell lines and examined the effect of ZEB1 on EPI- or ETOP-induced phosphorylation of histone H2A(γH2AX), which is the marker of DNA damage. The results showed that ZEB1 overexpression significantly reduced EPI or ETOP-induced production of γH2AX.Conversely, ZEB1 depletion resulted in the opposite effect to increased cell growth inhibition induced by EPI or ETOP. According to the previous results, we speculated that ZEB1 may play a role in DNA damage. So we further detected the expression of ZEB1 in clinical specimens and identify its correlation with the anti-apoptotic factor Bcl-xl and cell cycle factor Cyclin D1 by immunohistochemistry. The results indicated a positive correlation between ZEB1 and these two factors, highlighting that increased expression of ZEB1 contributes to the cellular mechanisms that mediate breast cancer chemoresistance. In order to identify endogenous transcriptional targets of ZEB1 in MDA-MB-231 cells, we performed the Ch IP-seq and identified 147 genes which bound by ZEB1. Among them, 9genes have been reported to function in the regulation of drug resistance during tumorigenesis. Considering ATM has been shown to regulated DNA damage, we performed Real-time PCR and WB to verify the expression of ZEB1 and ATM. The results showed positive correlation between ZEB1,ATM and p-ATM in breast cancer cells. The mechanism of this study opened a new chapter for ZEB1 in chemotherapy resistance.