PURPOSE - Although deletions or inactivating mutations of the tumor suppressor gene PTEN (phosphatase and tensin homolog deleted on chromosome 10) are involved in the development of a variety of tumors including glioblastoma, melanoma, prostate cancer, breast cancer, endometrial cancers etc., the role of PTEN expression in human primary hepatocellular carcinoma (HCC) has not yet been clarified. The aim of this study is to investigate the involvement of PTEN mRNA and protein expression in HCC.
METHODS - The level of PTEN mRNA expression in HCC specimens was analyzed by Northern blot. PTEN poly-clonal antibody was raised by immunizing New Zealand white rabbit with (His)(6)-tagged PTEN fusion protein and characterized by Western blot. The level of PTEN protein expression was determined by immunohistochemistry. The significance of PTEN in HCC was analyzed by comparing its expression level with the clinicopathological parameters of HCC patients.
RESULTS - Four transcripts of PTEN mRNA at 5.5 kb, 4.4 kb, 2.4 kb, and 1.8 kb were detected in most para-carcinoma liver tissues, and the expression level of PTEN mRNA in carcinoma liver tissues was found to decrease significantly. The poly-clonal antibody raised against histidine-tagged fusion PTEN protein showed specific immuno-reactivity to PTEN protein. Using the specific poly-clonal antibody prepared and characterized by ourselves, we found that PTEN protein was significantly down-regulated in HCC tissues compared with paired para-carcinoma tissues. The protein expression of PTEN is negatively associated with the pathological grading and presence of cancer thrombus of HCC.
CONCLUSIONS - Down-regulation of PTEN expression may play an important role in the development of HCC and the level of PTEN expression may be a potential adjuvant parameter in forecasting the progression and prognosis of HCC patients.