The Study Of PTEN/MMAC1/TEP1 Tumol Suppressor Gene In Human Malignant Melanoma And Its Significance

[Purpose] To study the change of tumor suppressor gene cloned recently, protein tyrosine phosphatase--PTEN/MIvIAC1/TEPI in Malignant Melanoma (MM) samples and its clinical pathological significance ; to further understand the mechanism of action of the gene on the malignant melanoma cell line and make a groundwork for exploiting its localization and molecular biological function in the signal transduction pathway of the tumor cells in the future.[Methods] The levels of protein of PTENIMIMAC 1 /TEP 1 tumor suppressor gene in MM samples were investigated by the numbers by using molecular biological, immunological and pathological techniques: (1) The special rabbit anti-human PTEN/MMAC 1 /TEP 1 tumor suppressor gene cDNA coding region polyantibody was raised. Using the immunohistochemical staining method, the localization and expression level of PTEN/MIvIAC1/TEP1 protein in 25 cases of formalin-fixed. paraffin-embedded MM tissue and paracarcinoma, 6 cases of nevus tissue sections were tested and compared to clinical pathological parameters; (2) We select lipofectin-mediated gene transfection method to create a stable cell line expressing exogenous PTEN for dual selection. Using Northern blotting hybridization and Western blotting hybridization method, the expression levels of PTENIMMAC 1/TEP 1 tumor suppressor gene were detected in human malignant melanoma cell line after transfection toconfirm the expression of target gene.[ Results ] (1) The protein expression of PTEN/MMAC1/TEPI tumor suppressor gene was clearly localized in the melanoma cell cytoplasma. The PTEN/MMAC1/TEPI protein expression level was lower and absent in MM samples compared with paracarcinoma normal tissue. The protein expression level of PTEN/MMAC1/TEP1 tumor suppressor gene in 25 cases of MM samples was significantly associated with metastasis (PO.05). (2) Northern blot and Western blot confirmed that the exogenous PTENIMIVIAC 1ITEP 1 gene expressed in the stable cell line in the presence of ponasterone A. The in vitro growth of pIND-SPI-PTEN transfected SK-MEL-3 1 cells with ponasterone A induction was significantly inhibited as compared to pIND-SPI transfected SK-MEL-3 1 cells. Colony-forming activity in vitro of the pIND-SPI-PTEN transfected SKMIEL-3 1 cells was inhibited too. Morphologically, the pJND-SPI-PTEN transfected SK-MIEL-3 1 cells appeared apoptotic which was confirmed by the appearance of pre-G on flow cytometry and DNA fragmentation.[Conclusion] PTEN/MMAC 1 /TEP 1 gene is a clear related suppressor gene of MM. It plays an important role in the mechanisms of the oncogenesis and tumor progression of MM. It is suggested that PTEN/MMAC 1 /TEP 1 tumor suppressor gene expression in MM samples should be a new adjuvant diagnostic index for judging tumor pathological biological behaviors, such as tumor cell differentiation, invasion and metastasis, etc. PTEN/MMAC 1/TEP1 gene participates in the induction of cell apoptosis. It is promising to be use it for gene therapy of cancer, especially when combined with other apoptosisinducing agents.