The Expression Of Histidine Phosphatase LHPP In Hepatocellular Carcinoma And Its Clinicopathological Significance

Primary liver cancer is the second leading cause of cancer-related deaths globally,hepatocellular carcinoma(HCC)accounts for 90% of primary liver cancer.It has strong malignant biological behaviors such as proliferation,invasion and metastasis,and the overall survival rate is low.The pathogenesis of hepatocellular carcinoma is complex and the effect of molecular targeted therapy is not significant,so finding new therapeutic targets is a hot topic of recent research.Phosphorylation is the most important and common post-translational modification of proteins,it plays an important regulatory role in life activities.Phosphorylation of proteins is catalyzed by protein kinases,and the reversal process is catalyzed by protein phosphatases,known as protein dephosphorylation.Phosphorylation and dephosphorylation are a reversible dynamic process,which is an important way to regulate biochemical and biological processes,including cell proliferation,apoptosis,differentiation,tumorigenesis,etc.The destruction of dynamic balance can lead to many diseases.In the reported literature,phosphorylation and dephosphorylation can affect the cycle of cells of hepatocellular carcinoma [1],apoptosis [2],tumor progression [3],angiogenesis in hepatocellular carcinoma [5],sensitivity of the tumor cells to targeted drugs [4] and recurrence [6],etc.Due to the instability of histidine phosphate and the limitations of detection methods,the true identified histidine-containing protein is rare,and there are few studies and reports on histidine phosphatase.Currently,the only known mammalian histidine protein kinases are nucleoside diphosphate kinase 1(NME1)and nucleoside diphosphate kinase 2(NME2).There are three kinds of histidine phosphatases reported: 14 k Da phosphohistidine phosphatase(PHPT1/PHP14),Phospholysine phosphohistidine inorganic pyrophosphate phosphatase(LHPP)and Phosphoglycerate mutase family 5(PGAM5).PHP14 is involved in the migration of hepatic stellate cells and flaky pseudopodia formation,neuronal signaling and effects on pancreatic beta cells,which may be involved in cell proliferation in hepatocellular carcinoma and lung cancer.There are few reports on the histidine phosphatase LHPP,which has recently been confirmed as a tumor suppressor.Hindupur SK et al found that histidine phosphatase LHPP is low expression in a mouse liver cancer model,while sustained histidine phosphatase LHPP can reduced tumor burden.Over expressing LHPP in CB1 and SNU449 cells can inhibit liver cancer proliferation,confirming histidine phosphatase LHPP is a tumor suppressor protein;Immunohistochemistry also showed that LHPP expression was low in HCC compared to adjacent non-tumour tissue from two additional patients.Hindupur SK et al found that LHPP expression is m TOR independent.The observations suggest that loss of LHPP and thus increased histidine phosphorylation is oncogenic.Zheng Jiangli et al reported that LHPP can inactivate Caspse-3 and PARP phosphorylation by activating AKT and inhibit apoptosis of human cervical cancer cells.Overexpression of LHPP can reduce the proliferation,migration and invasion of cells involved in P53 signaling pathway.Objective: There is no report on the immunohistochemical features of histidine phosphatase LHPP in human hepatocellular carcinoma samples.This study summarizes the expression of LHPP in hepatocellular carcinoma and adjacent tissues and explore the clinicopathological significance of hepatocellular carcinoma in relation to clinical pathological factors.Methods: This research is carried out with the approval of the Ethics Committee of China Medical University.The 151 hepatocellular carcinoma tissues were collected from the Department of Pathology,the First Affiliated Hospital of China Medical University from 2015 to 2018.These tissues were fixed in 10% neutral formalin and embedded in paraffin.None of the patients received radiochemotherapy before surgery and had the history of other primary malignant tumors and hepatic schistosomiasis.The diagnosis and its degree of differentiation were determined according to the WHO classification criteria.The paraffin-embedded hepatocellular carcinoma tissue was cut into 4 ?m sections,and baked in a 70 ° C oven for 3 hours for immunohistochemical staining.According to the results provided by The Human Protein Atlas database,We presume the positive signal locats in the cytoplasm of cancer cells and develop a scoring system: according to cytoplasmic staining intensity : 0 points: no coloration,1 points: light yellow,2 points: claybank;according to the percentage of positive cancer cells occupied by the five high-power fields(400 times)observed: 1 point: ?25% cancer cell coloring;2 points: 26-75% cancer cell coloring;3 points: ?76% cancer cell coloring;The final score is the product of staining intensity score and percentage score.It is negative when the final score is lower than 4,otherwise it is positive.The data was conducted statistical analysis by SPSS 20.0 software.The chi-square test was used and P<0.05 was considered statistically significant.Results: 1.The expression of histidine phosphatase LHPP is negative in paracancerous liver tissues,and the positive rate in hepatocellular carcinoma is 78.8%(119/151).2.The relationship between histidine phosphatase LHPP expression and the clinicopathological characteristics of hepatocellular carcinoma.2.1 The positive expression of histidine phosphatase LHPP in hepatocellular carcinoma was significantly correlated with the degree of hepatocellular carcinoma differentiation(P=0.002),Ki-67 index(P=0.022)and serum alpha-fetoprotein levels(P=0.005).2.2 The expression of LHPP was not related to the patient's gender,age,HBV infection,cirrhosis and tumor TNM stage.3.There was no significant difference in the expression of histidine phosphatase LHPP and immunohistochemical AFP,GPC-3 and Arginase-1 in hepatocellular carcinoma.Conclusion: 1.The expression of histidine phosphatase LHPP is enhanced in hepatocellular carcinoma.2.Histidine phosphatase LHPP expression is associated with tumor differentiation,Ki-67 index and serum alpha-fetoprotein levels.3.Histidine phosphatase LHPP may be associated with the malignant biological behavior of HCC,which may be a new indicator for diagnosis and prognosis.