Expression Of PiR-9994 And PiR-30715 In Gastric Cancer And Their Correlation With PIWIL4

Objective: PiRNA(Piwi-interacting RNA)is a specific expression of endogenous small molecule non-coding RNA,which is mainly expressed in germ cells and usually binds to PIWI protein and plays a biological role.In recent years,abnormal expression of piRNA was found in more and more tumor cells,while the expression of piRNA in gastric cancer and its correlation with PIWI protein were less reported.The purpose of this study was to search for piRNAs differentially expressed in gastric cancer(GC)tissues and adjacent tissues,and analysis of their expression pattern and correlation with clinicopathological characteristics of GC patients.To explore the correlation between piRNA and PIWIL4 expression and its role in the prognosis of GC patients,and reveal the potential value of piRNAs in the clinical diagnosis and treatment of GC.Methods: 1.Collecting the GC tissues and adjacent tissues of 50 patients in a third-class A hospital in Fujian Province from 2014 to 2015,and following up the prognosis of the patients 2.Extracting the total RNA of GC and adjacent tissues,and screening their differentially expressed piRNA by human piRNA chip.3.RT-qPCR was used to detect the differential expression of piRNA in GC and adjacent tissues.4.Fabricating Tissue Miroarray(TMA)from GC and adjacent tissues.And detecting the expression of PIWIL4 in GC and adjacent tissues by immunohistochemistry.5.Based on the follow-up information of GC patients,the relationship between piRNA and PIWIL4 and overall survival rate was analyzed,and the role of piRNA and PIWIL4 in the prognosis of GC patients was explored.Results: 1.50 differentially expressed piRNAs were found in GC and adjacent tissues by human piRNA chip.17 of them were highly expressed and 33 were low expressed in GC.Two piRNAs closely related to gastric cancer,piR-hsa-9994 and piR-hsa-30715,were further screened through preliminary experiments.2.The expressions of piR-9994 and piR-30715 in GC tissues were significantly higher than those in adjacent tissues(P < 0.01).3.The expression of piR-9994 in GC with invasion depth of T3 and T4 was four times higher than that of T1 and T2(P=0.023),.The expression of piR-9994 in stage III and IV was 4.6 times higher than that in stage I and II of gastric cancer(P=0.001).The expression of piR-9994 in lymph node metastasis group was three times higher than that in non-metastasis group(P=0.045).4.The expression of piR-30715 in GC with invasion depth of T3 and T4 was 4.4 times higher than that in T1 and T2(P=0.034).The expression of piR-30715 in stage III and IV was6.2 times higher than that in stage I and II of gastric cancer(P<0.001).The expression of piR-30715 in lymph node metastasis group was 5.1 times higher than that in non-metastasis group(P=0.017).5.The expression rate of PIWIL4 in GC was 46%(23/50),which was significantly higher than 14%(7/50)in adjacent tissues(?2=12.190,P<0.001).6.The expression of piR-9994 was positively correlated with the expression of PIWIL4 in GC(r=0.318,P=0.024);the expression of piR-30715 was positively correlated with the expression of PIWIL4 in GC(r=0.333,P=0.018).7.Overall survival rate(OS)of piR-3071 high expression group was lower than that of piR-3071 low expression group(P=0.024).The overall survival rate of the PIWIL4 positive expression group was worse than that of the negative expression group(P=0.025).PIWIL4 was an independent adverse prognostic factor for GC.Conclusions: 1.Overexpression of piR-9994 in GC tissues is closely related to the depth of invasion,TNM stage and lymph node metastasis.piR-9994 may participate in the occurrence and development of GC by regulating PIWIL4 expression.piR-9994 may be a molecular marker for the diagnosis of GC and judging the malignant degree of GC.2.Overexpression of piR-30715 in GC tissue is closely related to the depth of invasion,TNM stage,lymph node metastasis and prognosis of GC patients.piR-9994 may participate in the occurrence,development and metastasis of GC by regulating the expression of PIWIL4.piR-30715 may be a molecular marker for the diagnosis of GC,the differentiation of malignant degree and prognosis of GC.