Clinicopathological Significance Of CDK12 Expression In Pancreatic Cancer

Objective Pancreatic cancer is one of the most challenging gastrointestinal malignancies in the world.It is the fourth leading cause of death among all malignancies and its five-year survival rate are only 5%.Due to the development of medical technology,the diagnosis and treatment of pancreatic cancer have been greatly improved,but there are still no effective drugs for the treatment of pancreatic cancer.CDK12 is one of the transcription-related cyclin-dependent kinases,which can phosphorylate serine in the carboxy terminal domain of RNA polymerase Ⅱ(RNA pol II CTD).CDK12 plays an important role in the occurrence and development of various tumors.By examining the expression of CDK12 in pancreatic cancer cell lines and tissues,and analyzing the correlation between the expression of CDK12 and the clinicopathological characteristics of patients with pancreatic cancer and its impact on the survival prognosis of patients,this study aims at helping patients with pancreatic cancer in the assistant diagnosis,targeted therapy,and assessment of patients’ survival prognosis.Methods1.Bioinformatics analysisThe expression levels of CDK12 in human tissues are analyzed through HPA database,and then the CDK12 mRNA expression in human tumors tissues and cells is analyzed through CCLE database,GENT database and GEPIA database.After that,by using cBioPortal Database,Oncomine database,UCSC Xena database,GEPIA database and CCLE database,HPA database,the study could make analyses of CDK12 mutations,CDK12 mRNA,protein expression and the relative expression of CDK12 in 41 pancreatic cancer cell lines.Meanwhile,the correlation between CDK12 expression and survival prognosis of pancreatic cancer patients is tested through the Oncolnc database and HPA database.2.Experimental verificationThe study mainly uses RT-PCR,Western blot,and immunohistochemical staining in order to verify the expression of CDK12 in pancreatic cancer cells,normal pancreatic cells and 60 cases of pancreatic cancer tissues and the corresponding para-carcinoma tissues.At the same time,the clinical and pathological data of the patients are collected and the follow-up prognostic is performed.Then the survival time of pancreatic cancer patients is described by Kaplan-Meier curve and log-rank test,and the clinical and pathological data are statistically analyzed.Finally,the diagnostic and prognosis value of CDK12 in pancreatic cancer is evaluated through the Cox regression model.Results1 The expression levels of CDK12 in human tissues and cells are generally high,the expression score of CDK12 protein is relatively high in the pancreas,however,the expression level of CDK12 RNA is relatively low.2 CDK12 is highly expressed in a variety of tumor tissues including pancreatic adenocarcinoma(PAAD).Compared with normal pancreatic tissue,the number of CDK12 in pancreatic cancer has increased by 2.41 times.3 There are 6 mutation sites beyond the P kinase domain in CDK12 protein.CDK12 has different mutation frequencies in different data concentrations.The main forms of CDK12 mutation is amplification.Pancreatic cancer CNAs is related to the expression level of CDK12.4 The analysis results of Oncomine,UCSC Xena,GEPIA,HPA database show that the expression levels of CDK12 mRNA and protein in pancreatic cancer are significantly higher than those in normal pancreatic tissue(p <0.05).According to CCLE database analysis,the expression levels of CDK12 mRNA(-log2)in AsPC-1,BxPC-3,PANC-1,and MIA-PaCA2(the four pancreatic cancer cells)are greater than 3,with relatively high level.5 The analysis results from Oncolnc database,HPA database show that PAAD patients with high expression of CDK12 have significantly lower survival rates in PAAD patients with low expression of CDK12(p <0.05).6 RT-PCR and Western blot results suggest that compared with normal pancreatic cells,CDK12 RNA and protein expression in pancreatic cancer cells are greatly increased(p <0.05),which is line with previous predictions.7 The immunohistochemical results testify that the positive expression rate of CDK12 in 60 cases of pancreatic cancer tissue is 73.33%(44/60),while it takes up 21.66%(13/60)in the corresponding para-carcinoma tissues.The expression level of CDK12 is significantly related to tumor diameter of patients with pancreatic cancer,lymph node metastasis,TNM stage and differentiation degree and tumor marker(p <0.05).8 The test results of Kaplan-Meier curve and log-rank suggest that the survival time of pancreatic cancer patients with high expression of CDK12 is significantly shorter than that of patients with low expression(p <0.05).Cox regression model also suggests that the expression level of CDK12 is obviously associated with the prognostic survival of pancreatic cancer patients,and the high expression of CDK12 is an independent and prognostic risk factor for pancreatic cancer patients.(p <0.05).Conclusion CDK12 is highly expressed in pancreatic cancer cell lines and tissues,and the expression level of CDK12 is significantly related to the survival prognosis of patients with pancreatic cancer.Compared with the pancreatic cancer patients with low expression of CDK12,the prognosis of patients with high expression of CDK12 is worse.The high expression of CDK12 is an independent risk factor to the survival prognosis of pancreatic cancer patients.CDK12 may be a new-type biomarker for assessing the prognosis of pancreatic cancer patients and it provides a new target for targeted therapy of pancreatic cancer patients.