1Departments of Microbiology, Keimyung University School of Medicine, Daegu. 2Departments of Immunology, Keimyung University School of Medicine, Daegu. 3Department of Microbiology, Seonam University, Namwon. 4Department of Pathology, Taegu Hyosung Catholic University, College of Medicine, Daegu, Korea.
ABSTRACT
PURPOSE: We analyzed the gene status of p16INK4A, p15INK4B and MTAP (methylthio adenosine phophorylase) in Korean hepatdegrees Cellular carcinoma (HCC) to investigate whether the inactivation of these genes participated in hepatdegrees Carcinogenesis, and evaluated MTAP-targeted chemotherapy in MTAP-deficient cell lines.
MATERIAL AND METHODS: We examined eleven primary HCC and 8 SNU cell lines using PCR, Southern blot analysis, PCR-SSCP, DNA sequencing, methylation-specific PCR, Western blot analysis, MTT assay, and crystal violet staining.
RESULTS: Mutations or deletion of the p16INK4A, 15INK4B, and MTAP genes were rare, but methylation of the p16INK4A promoter region was common in HCC. The base alterations of 3' untranslated region of p16INK4A exon 3 were also detected in 3 samples. In SNU cells, p16INK4A was not detectable, when treated with demethylating agent, high levels of re-expressed p16INK4A protein were detected. In MTAP-targeted chemotherapy experiment, methylthioadeno sine (MTA) was able to rescue MTAP positive cell lines but not MTAP negative cell lines from growth inhibition by depletion of methionine and MTX treatment.
CONCLUSION: These results suggest that de novo methylation of the p16INK4A promoter region seems to play an important role in the pathogenesis of HCC.
And treatment of MTX, combined with methionine depletion in the presence of MTA, may be a high selective treatment for MTAP negative HCC.
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