| Background:Prostate cancer and bladder cancer are tumors with the highest incidence rate of urinary system in western countries and in China. Although its incidence in China is relatively lower than common malignant tumors, e.g. tumors in respiratory system or digestive system, prostate cancer and bladder cancer incidence have an obvious trend of rising and its importance in the research of tumor is more and more attractive. Although the development of diagnostic technology and popularization of ultrasound and CT can greatly improve the rate of early detection of prostate cancer and bladder cancer, there are still lots of patients seeking treatment in advanced stage of cancer because of the symptoms, leading to delay of treatment. As the incidence of prostate cancer is in the first place in of all tumors and it is in second place of tumor related death in the Western countries, the research on prostate cancer is always the focus of attention of many western scholars. Although incidence of prostate cancer in China is relatively low, its growth has gradually accelerated in recent years. Thus, the domestic research about the mechanism of prostate cancer is gradually warming. As for bladder cancer, which is a urinary system tumor with the highest incidence in our country, has high recurrent obvious, and there is no effective clinical treatment at present. Besides, role of conventional pathological grading and staging methods in predicting biological behavior of bladder cancer is limited. Therefore, deep study into change of molecular biology in prostate cancer and bladder cancer will be greatly beneficial for early diagnosis and clinical treatment of the disease. The research also has important and positive significance in the promotion of scientific research and clinical progress.Like other malignant tumors, the incidence of prostate cancer and bladder cancer involved environmental factors and genetic factors. Previous studies have found a series of gene variations causing abnormal gene functions and cell biological behavior participated in carcinogenesis of prostate cancer and bladder cancer. However, with the development of research in molecular genetic mechanisms of tumor, it is gradually accepted that epigenetic mechanism also plays a vital role in carcinogenesis. pigenetic mechanisms studied widely include chromatin remodeling, histone modifications, DNA methylation, regulation of functional (noncoding) RNAs etc..LncRNA, also known as long noncoding RNA, is a kind of functional RNAs in length of more than 200nt, without protein coding capacities. Many studies have shown that lncRNA play multiple roles in cells. In addition, lncRNA with different locations may play a regulatory role through different mechanisms. With the continuous discovery of genome lncRNA, their roles in carcinogenesis attracted more and more concern. Abnormal expression of specific lncRNA have been observed in a series of tumors, such as lung cancer, liver cancer and breast cancer, suggesting a relationship between lncRNA and biological processes in occurrence of tumor. However, up to now, research about the mechanism of lncRNA is still in the initial stage, and their detailed role in the prostate cancer and bladder cancer needs further explanation.We screened for lncRNAs differently expressed in prostate cancer and bladder cancer through literatures and microarrays respectively. A series of molecular biology assays were also conducted to clarify their role in carcinogenesis and the possible molecular mechanisms. The present study provides theoretical basis for further revealing of lncRNArole in the pathogenesis of prostate and bladder cancer. Besides, it provides important reference for the individualized prevention, early intervention and diagnosis of cancers in urinary system.Part1 Mechanism of lncRNA intronic-ABCA1 in carcinogenesis of prostate cancerBackground:Prostate cancer has the first incidence of malignant tumors in western countries. ABCA1 is a macromolecular membrane lipid transporter with important functions. The main biological function of it is to transport of cholesterol from inside to outside of cells, and pack it into high density lipoprotein. Through this mechanism, ABCA1 is involved in the occurrence and development of prostate cancer. Intronic-1ncRNA located in this gene region may regulate gene expression, and affect the pathogenesis of prostate cancer.Methods and Results:By reading literatures, we found ABCA1 gene may be involved in the occurrence and development of prostate cancer, and further bioinformatics query also showed that there is an intronic lncRNA located in the gene region. It was named intronic-ABCA1 in the present study. RT-PCR assay detected that the expression of lncRNA intronic-ABCA1 are decreased in prostate cancer tissues, compared with that in adjacent nontumor tissues. Overexpress vector of intronic-ABCA1 was constructed and then transfected into prostate cancer cell lines. Results of RT-PCR and Western blot showed that the expression level of protein-coding ABCA1 gene significantly inhibited by intronic-ABCA1 in both RNA level and protein level. CCK-8 and transwell assays were then performed to detect the effect of intronic-ABCA1 on proliferation and migration of prostate cancer cells and a significant inhibition role of intronic-ABCA1 in cell proliferation and migration ability were found. Results also indicated that this effect may be related to the regulation of ABCA1 expression.Conclusion:Our study found that lncRNA intronic-ABCA1 was decreased in prostate cancer tissues and exert an negative regulatory role on its adjacent conding gene ABCA1. It can significantly inhibit proliferation and migration of prostate cancer cells.Part2 Inhibition role of lncRNA MDC1-AS in bladder cancer and the molecular mechanismBackground:Bladder cancer is the most common malignant tumor of urinary system, and has high recurrent rate. Regulation of antisense lncRNA was involved in the biological process through a variety of mechanisms. MDC1 is an important molecular in DNA damage response process and acts as a tumor suppressor in a variety of tumors.Methods and Results:LncRNA microarray screen of 3 pairs of bladder cancer tissues and adjacent nontumor tissues were performed. We found an lncRNA antisense to DNA repair gene MDC1 had a significantly lower expression in cancer tissues, and we named it MDC1-AS in our study. The subsequent RT-PCR assay of validation sample confirmed the significant down-regulation of MDC1-AS in bladder cancer and found that its adjacent encoding gene MDC1 were also decreased in bladder cancer, further correlation analysis showed that the expression level of them had a significantly positive correlation. MDC1-AS overexpression vector was constructed and then transfected into bladder cancer cells EJ and T24. An upregulated role of MDC1-AS on the expression of MDC1 gene was observed. Further CCK-8, transwell, plate cloning and flow cytometry detect that MDC1-AS exerted an evident inhibition role on proliferation, migration and formation of clones of bladder cancer cells. Finally, in order to explore whether the effects of MDC1-AS was related to its regulation role on MDC1 gene, siRNA was used to inhibit MDC1 expression and the inhibitory effect of MDCl-AS on the malignant phenotype of cancer cells was found to decrease obviously. Therefore, it can be inferred that the inhibitory role of MDC1-AS on the malignant phenotype of bladder cancer cells was related with its positive regulation of MDC1 gene.Conclusion:We identified a novel lncRNA MDC1-AS, which was significantly decreased in bladder cancer tissues and can upregulate MDC1 gene. MDC1-AS can inhibit the proliferation, migration and clone formation of bladder cancer cells, and this inhibition was associated with its role in the regulation of MDC1.The results of this study not only explain the role of lncRNA in carcinogenesis and development of urinary system cancers, but also provide clues for novel clinical biomarkers. Besides, it provide basis for understanding the role and its mechanism of lncRNA in carcinogenesis. |
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