The Mechanism Of Protein Arginine Methyltransferase PRMT7 Promoting Prostate ’Cancer Cells’ Proliferation And Invasion

Prostate cancer(PCa)has become a major public health challenge affecting men worldwide,as the global population increases and the problem of population aging increases year by year.Prostate cancer is a highly prevalent malignancy,the second most common cancer in men worldwide,and the leading cause of cancer death in men.The high risk of prostate cancer is mainly due to its aggressive metastasis.In fact,due to the hidden nature of the tumor,it is difficult for clinicians to diagnose and treat the disease early.Prostate cancer is considered as a highly heterogeneous cancer characterized by multiple genomic alterations.Androgen castration therapy(or testosterone therapy)is effective in the early stages of advanced prostate cancer.However,advanced prostate cancer usually progresses even after androgen ablation,developing into a fatal castration-resistant prostate cancer.Patients at this stage have an increased risk of bone metastasis and a poor prognosis.Therefore,further research on the mechanism of prostate cancer,and search for more specific early diagnosis indications as well as more effective therapeutic targets and treatment plans are of great significance for improving the quality of life of patients,extending the overall survival time and improving the survival rate of patients.Histone methylation is carried out by histone methyltransferases(HMTs),which require different families of enzymes to be dependent on their respective residues and may positively or negatively regulate gene transcription.In which the protein arginine methyltransferase methylates arginine,PRMT7 is the only representative of its type Ⅲ group and only monomethyl arginine.Multiple studies have shown that PRMT7 and its protein-regulated post-translational modification are associated with tumor proliferation and metastasis.PRMT7 is likely to play a key role as an epigenetic regulator in prostate cancer and ultimately influence tumor progression and cancer prognosis.In previous studies,we refer to Filipa et al.’s study on protein arginine methyltransferase in prostate cancer.A total of 159 prostate cancer patients from the Affiliated Hospital of Jiangnan University from 2020 to 2022 were collected,and the correlation between PRMT7 and the age,Gleason grade,PSA,TNM stage and survival rate of prostate cancer patients was analyzed by using tissue chip technology and Kaplan-Meier method.It was found that PRMT7 gene expression was significantly correlated with PSA in prostate cancer patients.Subsequently,the influence of PRMT7 on the biological function of prostate cancer cells was explored through in vitro and in vivo molecular biology experiments,and the downstream signaling pathway with PRMT7 was predicted by online database and transcriptome sequencing,and finally the relevant verification was carried out.Our study provides insight for finding prognostic markers and therapeutic targets for prostate cancer diagnosis.Part Ⅰ Expression and clinical significance of PRMT7 in prostate cancer Objective:Tissue microarray technology was used to analyze the tissues of prostate cancer patients,identify the correlation between PRMT7 and the prognosis of prostate cancer patients,and verify the expression level in prostate cancer tissues and cell lines.Methods:(1)TCGA was used to analyze the correlation between PRMT7 and prostate cancer.(2)Tissue chip technology and Kaplan-Meier method were used to analyze the correlation between PRMT7 and prostate cancer patients’ age,Gleason grade,PSA,TNM stage and survival rate.(3)The expression level of PRMT7 in patient tissues was analyzed by tissue chip technology.(4)The expression level of PRMT7 in prostate cancer tissues and cells was verified by RT-qPCR.(5)The protein structure of PRMT7 queried by Uniprot,a public database.Results:(1)By analyzing the relevant data of PRMT7 and prostate cancer in the public database TCGA,it was found that the expression level of PRMT7 was significantly correlated with cancer and adjacent tissues,age of prostate cancer patients,Gleason grade,PSA,TNM stage and survival rate.(2)Analysis of 159 patients with prostate cancer using tissue chip technology found that PRMT7 expression level was significantly correlated with PSA in prostate cancer patients.(3)Tissue microarray showed abnormal expression of PRMT7 in patient tissues.(4)The results of RTqPCR showed that PRMT7 was highly expressed in prostate cancer tissues and cells.(5)The protein structure of PRMT7 was queried by Uniprot,a public database.Conclusion:According to TCGA screening and the microarray of prostate cancer tissue,PRMT7 was found to be associated with poor prognosis,and PRMT7 was highly expressed in prostate cancer tissues and cells.Part Ⅱ Effects of PRMT7 on biological behavior of prostate cancer cells Objective:The effect of PRMT7 on the biological behavior of prostate cancer cells was investigated in vitro and in vivo.Methods:(1)The transfected plasmid interfered with siRNA in prostate cancer cell lines,and their transfection efficiency was detected by RT-qPCR;(2)Changes in proliferative activity and clonogenesis of prostate cancer cells after downregulating PRMT7 expression were detected by CCK8 assay and plate cloning assay.(3)Scratch healing assay was used to detect the change of migration ability of prostate cancer cells after downregulating PRMT7 expression.(4)Transwell assay was used to detect changes in the migration and invasion ability of prostate cancer cells after downregulating PRMT7 expression.(5)Flow cytometry was used to detect the effect of down-regulated PRMT7 on apoptosis and cell cycle of prostate cancer cells.(6)The effect of down-regulated PRMT7 on the growth and proliferative activity of prostate cancer tumor grafts in nude mice was tested by subcutaneous tumor carrying experiment.Results:(1)Plasmid siRNA transfected in prostate cancer cell lines can significantly downregulate PRMT7 expression;(2)The results of CCK8 and plate cloning experiments showed that knockdown of PRMT7 significantly inhibited the proliferative activity and clonogenesis of prostate cancer cells.(3)The results of scratch healing experiment showed that the migration ability of prostate cancer cells decreased after PRMT7 knockdown.(4)Transwell assay showed that knockdown of PRMT7 inhibited the migration and invasion of prostate cancer cells.(5)Flow cytometry showed that downregulation of PRMT7 could lead to cycle arrest and promote apoptosis of prostate cancer cells;(6)The results of subcutaneous tumor bearing in nude mice showed that PRMT7 could promote the growth and proliferation of prostate cancer transplant tumors in vivo.Conclusion:In vitro biological experiments,PRMT7 can significantly promote the proliferation,migration,invasion and apoptosis of prostate cancer cells,and affect cell cycle.In vivo,PRMT7 can significantly promote the growth and proliferation of prostate cancer cells in nude mice.Part Ⅲ PRMT7 promotes malignant progression of prostate cancer by affecting cell cycle-related pathways Objective:To explore the potential effect pathway and mechanism of PRMT7 in prostate cancer.Methods:(1)Combined with PRMT7 transcriptome sequencing results,differential genes were screened.(2)Gene enrichment analysis and database(STRING)information were used to predict the potential pathway of PRMT7 in prostate cancer.(3)Western blot analysis was performed to verify the corresponding proteins of the predicted pathway genes.Results:(1)Combined with transcriptome sequencing results,it was found that 1085 differential genes were up-regulated and 878 genes were down-regulated after knockdown of PRMT7.(2)Enrichment analysis of differential genes obtained by transcriptome sequencing showed that most of the differential genes in prostate cancer cells after PRMT7 knockdown had the ability to regulate cell cycle function.(3)Combined with transcriptomic sequencing and database screening,PRMT7 was predicted and verified by Western blot to participate in YY1 / TP53 / CCND2 / CDK6/ RB1 cell cycle signal axis and affect the cycle of prostate cancer cells,and promote the progression of tumor.Conclusion:PRMT7 regulates YY1 / TP53 / CCND2 / CDK6 / RB1 cell cycle signaling axis and affects the cycle of prostate cancer cells,thus participating in the malignant progression of tumors.