Function And Molecular Mechanism Of Long Non-coding RNA MALAT1 In Prostate Cancer

Background:Prostate cancer(PCa),the male second most common cancer,has a high incidence rate and high mortality rate,accounting for 13% of the cancer related mortality.The identified risk factors include race?age? family history and androgen levels.In the pathophysiology of PCa,androgen is an essential steroid hormone in the human body.It plays an important role in controlling the development?growth and differentiation of prostate through androgen receptor.When androgen is removed,prostate cell apoptosis will occur,which plays a key role in the development and maintenance of male characteristics.Clinical studies have found that there is a direct relationship between the imbalance of androgen regulation and the pathogenesis of PCa.Therefore,AR antagonists and chemical castration therapy are often used in the treatment of PCa.Androgen deprivation therapy(ADT)is an essential method in the clinical treatment process.However,in the long-term treatment process,the vast majority of primary PCa eventually acquired ADT resistance,and thus developed into castration resistant prostate cancer(CRPC),which is one of the difficulties and hot spots in clinical treatment of PCa.Therefore,further exploration of the pathogenesis of PCa will help us to understand the mechanism of the occurrence and development of PCa,to develop new diagnostic markers and prognostic indicators of PCa,to help us to find new targets for the treatment of PCa,and ultimately bring better benefits to patients.With the initiation and completion of Eencode project and the continuous development of high-throughput sequencing technology,scientists have found a large number of long non-coding RNA,and in the process of studying Lnc RNA,they are more aware that Lnc RNA plays an irreplaceable role in physiological and pathological conditions or in the occurrence and development of diseases.Especially in recent years,the research on Lnc RNA in cancer is the most extensive.Metastasis associated in lung denocarinoma transcript(MALAT1)was first found to be associated with metastasis of non-small cell lung cancer in 2003.A large number of studies have found that MALAT1 can also be overexpressed in tumors of different organs and systems,such as digestive system tumors and urinary system tumors.Although MALAT1 has also been reported in PCA research,the mechanism of MALAT1 in PCa is still less reported,and the relationship between MALAT1 and AR signaling pathway remains to be elucidated.Objets:(1)To clarify the role of MALAT1 in PCa tissue and to analyze the relationship between MALAT1 and PCa tissue.(2)In order to further explore the mechanism of MALAT1 in PCa,we studied in vitro how MALAT1 affects the occurrence and development of PCa and whether MALAT1 participates in the regulation of AR signaling pathway.By observing the effect of MALAT1 on PCa xenografts in nude mice,the effect of MALAT1 on PCa in vivo was further verified.(3)By studying the specific role and internal mechanism of MALAT1 in PCa,the possibility of MALAT1 as a new tumor marker and therapeutic target of PCa was discussed,which provided new ideas for the diagnosis and targeted treatment of PCa.Methods:(1)The expression of MALAT1 in PCa tissues and its clinical correlation with PCa were analyzed by bioinformatics technology.The diagnostic value of MALAT1 in PCa was analyzed by ROC curve.Gene enrichment analysis was used to predict the gene set enriched by MALAT1 with high expression in PCa.(2)Scratch test and Transwell chamber invasion test were used to detect the effect of MALAT1 silencing on the migration and invasion of PCa cells.(3)Western blot was used to detect the effect of silencing MALAT1 on epithelial mesenchymal transition of PCa cells.(4)CCK8 was used to detect the effect of silencing MALAT1 on the proliferation of PCa cells with or without androgen stimulation.(5)Flow cytometry was used to detect the effect of silencing MALAT1 on the cell cycle of PCa with or without androgen stimulation.(6)Western blot was used to detect the effect of MALAT1 silencing on cell cycle related proteins in PCa cells with or without androgen stimulation.(7)The candidate target gene mi RNA of MALAT1 was predicted by consulting the literature,and then the target 3'UTR of mi RNA seed sequence was predicted.(8)Double luciferase reporter gene experiment and rescue experiment were used to verify the mechanism of MALAT1/mi R-1-3p/CORO1 C and MALAT1/mi R-320b/AR signal axis in PCa.(9)Animal experiments were conducted to verify the effect of silencing MALAT1 on PCa xenografts in nude mice.Results:(1)The expression of MALAT1 in PCa tissues was significantly higher than that in adjacent tissues.The expression of malat1 with high or low was significantly correlated with Gleason score ? lymph node metastasis and differentiation.Disease free survival and progression free survival of patients with high MALAT1 expression were significantly lower than those with low expression of MALAT1.ROC curve analysis showed that MALAT1 had certain diagnostic value in PCa,and gene set enrichment analysis was used to predict MALAT1 expression MALAT1 was significantly enriched in invasion,metastasis and cell cycle regulation.(2)MALAT1 is highly expressed in LNCa P and 22Rv1.Silencing MALAT1 can inhibit the migration,invasion and epithelial-mesenchymal transition in LNCa P and 22Rv1 cells.Silencing MALAT1 with or without androgen inhibited the proliferation,cell cycle progression in LNCa P and 22Rv1 cells.(4)Androgen can stimulate the expression of MALAT1 and AR in LNCa P and 22Rv1 cells.Silencing MALAT1 can inhibit the expression of AR in LNCa P and 22Rv1 cells regardless of(3)The results of Shengxin analysis and double luciferase reporter gene experiments showed that mi R-1-3p could directly bind to MALAT1 and CORO1 C m RNA 3'UTR,MALAT1 could interact with CORO1 C m RNA 3'UTR and competitively bind to mi R-1-3p and promote the expression of CORO1 C.The rescue experiment confirmed that inhibition of mi R-1-3p or overexpression of CORO1 C could reverse the migration,invasion and epithelial-mesenchymal transition in LNCa P and 22Rv1 cells induced by MALAT1 silencing. androgen stimulation.Bioinformatics technology analysis and double luciferase reporter gene experiment proved that MALAT1 can bind to mi R-320 b,and MALAT1 and AR m RNA 3'UTR can compete for the binding site of mi R-320 b.The results of rescue experiments showed that inhibition of mi R-320 b or overexpression of AR could eliminate the changes of proliferation and cell cycle of PCa cells induced by MALAT1 silencing.(5)Silencing MALAT1 can inhibit the growth of PCa xenografts in nude mice,and reduce the expression of PSA and AR in tumor tissue.Conclusions:(1)MALAT1 is highly expressed in PCa tissues and cells,which may act as a tumor promoting gene to affect the occurrence and development of PCa.The expression level of MALAT1 has a certain reference value for the diagnosis and prognosis of PCa patients.(2)In vitro experiments showed that MALAT1 can regulate the expression of CORO1 C through MALAT1/mi R-1-3p/CORO1 C,and participate in AR signal pathway through MALAT1/mi R-320b/AR signal axis,to affect the development of PCa.(3)In vivo experiments confirmed that silencing MALAT1 can inhibit the growth of PCa xenografts in nude mice,which is expected to be a new target for prostate cancer therapy.