Down-regulation of arginase-1 expression and its clinical significance in hepatocellular carcinoma / 中国癌症杂志

ABSTRACT

Background and purpose: Arginase-1 (Arg-1) is an enzyme involved in the urea cycle. Research has shown that changed expression of Arg-1 plays an important role in the cellular metabolism and growth. The purpose of this research was to investigate the expression of Arg-1 in hepatocellular carcinoma (HCC) and to analyze its correlation with clinicopathological features. Methods: The expression of Arg-1 protein and mRNA in 31 samples of HCC, paracancerous liver tissues and 12 samples of normal liver was detected by Western blot and reverse transcription-polymerase chain reaction (RT-PCR). The expression profiles of Arg-1 at protein level in 158 samples of HCC and paracancerous liver tissues were detected with high-throughput tissue microarray technique and immunohistochemistry. The relationships between Arg-1 expression and clinicopathological features were also analyzed. Results:The expression of Arg-1 mRNA and protein was signiifcantly decreased in HCC compared with the paracancerous liver tissues and normal liver tissues (F=57.83, 160.89; all P<0.01). The expression of Arg-1 in HCC was related to differentiation degree (F=10.41, 30.03; all P<0.01). And with tumor differentiation decreased, the expression level down-regulated. Immunohistochemistry revealed that Arg-1 protein was mainly located in the cytoplasm and nuclear. The expression rates of Arg-1 were 88%, 98.7%and 100%in HCC, paracancerous tissues and normal liver tissues, respectively. Statistical analysis revealed that Arg-1 protein staining rate was signiifcantly lower in tumor tissues than that in paracancerous tissues (χ2=14.7416, P<0.01) and normal liver tissues (χ2=4.1415, P<0.05). The Arg-1 expression was correlated with differentiation degree of HCC, vascular invasion and recurrence after operation (χ2=22.8459, 10.2639, 10.6368 respectively;all P<0.05), but not correlated with age, gender, the hepatitis B virus, the level of serum AFP, liver cirrhosis, diameter of tumor and tumor number. Conclusion:The expression level of Arg-1 is much lower in HCC than that in the paracancerous liver and normal liver. Moreover, Arg-1 expression level is closely related to tumor differentiation degree, metastasis and relapse. These data demonstrate that Arg-1 may play a negative role in the development of HCC.