Association between the expression of somatostatin receptors and pathological features, prognosis in hepatocellular carcinoma

Objective To investigate the expression of somatostatin receptors (SSTRs) in hepatocellular carcinoma (HCC) tissue and its association with clinicopathological features and prognosis of HCC.Methods HCC samples were collected from 80 patients who visited Third Hospital of PLA and Department of Hepatobiliary Surgery in The Second Affiliated Hospital of Dalian Medical University and who underwent hepatectomy from July 2012 to December 2014 and were diagnosed with HCC based on postoperative pathology (trial group) .Another 80 patients who were suspected of liver disease and were not diagnosed with HCC by liver biopsy were enrolled as control group.RT-PCR and immunohistochemistry were used to measure the mRNA and protein expression of SSTR-2 and SSTR-3.The t-test was used for comparison of continuous data between groups, the chi-square test was used for comparison of categorical data between groups, the Kaplan-Meier method was used to analyze patients' survival, and the Cox regression analysis was used to investigate the influencing factors for the prognosis of HCC patients.Results The control group had significantly higher mRNA and protein expression of SSTR-2 and SSTR-3 than the trial group (t = 6.456 and 8.128, χ2= 7.992 and 9.157, all P < 0.05) .The univariate analysis showed that the mRNA expression of SSTR-2 and SSTR-3 was significantly correlated with tumor nodule (t = 6.533 and 5.041, both P < 0.05) , degree of tumor differentiation (t = 4.672 and 4.013, both P < 0.05) , depth of infiltration (t = 6.735 and 7.019, both P < 0.05) , viral hepatitis (t = 4.929 and4.535, both P < 0.05) , alcoholic hepatitis (t = 4.032 and 4.362, both P < 0.05) , and diabetes (t = 4.372 and 6.293, both P < 0.05) , and the protein expression of SSTR-2 and SSTR-3 was significantly correlated with tumor nodule (χ2= 25.223 and 15.399, both P <0.05) , degree of tumor differentiation (χ2= 7.535 and 10.944, both P < 0.05) , and depth of infiltration (χ2= 22.520 and 9.968, both P< 0.05) .Compared with the group with positive expression of SSTR-2 and SSTR-3, the group with negative expression had significantly lower cumulative postoperative disease-free survival rate (P = 0.015 and 0.004) and postoperative overall survival rate (P = 0.009 and <0.001) .The Cox model analysis showed that protein expression of SSTR-2 and SSTR-3, the number of tumor nodules, liver cirrhosis, and vein infiltration in HCC tissue were independent risk factors for overall survival after HCC surgery (P < 0.05) .Conclusion HCC patients have lower expression of SSTR-2 and SSTR-3 than non-HCC patients, and such low expression is closely associated with invasion/metastasis and poor prognosis of HCC.SSTRs may be the markers for the prognosis of HCC.