| Summary: | 碩士 === 長庚大學 === 基礎醫學研究所 === 96 === PTEN is a major tumor suppressor gene in phosphatidylinositol 3-kinase-AKT pathway (PI3K-AKT pathway) which plays an important regulatory role in cell growth, survival, and proliferation. PTEN mutation or deletion can give rise to abnormal expression of downstream protein in PI3K-AKT pathway, as well as aberrance of biochemical action and tumor progression. Although the frequency for loss of heterozygosity (LOH), homozygous deletion and protein expression of PTEN were varied in many cancers from different countries, aberrations of PTEN at gene or protein level were prevalent in tumor cells. Accordingly, this study was designed to investigate the frequency of LOH and homozygous deletion of PTEN gene, as well as its relationship with protein expression in 522 oral squamous cell carcinomas (OSCCs) in Taiwan. The frequency of PTEN allele loss was 27.4% (143/522). The frequency of LOH and homozygous deletion was 45.9 % (118/257) and 9.4 % (25/265) respectively. The expression of PTEN was evaluated by immuno- histochemistry and we found that reduced protein expression in tumor cells was not associated with allele loss. The frequency of allele loss of PTEN gene was not associated with age, tumor stage, overall and disease-free survival rate. However, allele loss of PTEN gene was correlated with histologic grade (p=0.031). In addition, the overall survival of OSCC patients with homozygous deletion of PTEN was inferior than those patients without homozygous deletion of PTEN (p=0.039). Cigarette smoking and alcohol drinking did not show significant association with allele loss of PTEN, while betel quid chewing was associated with reduced allele loss of PTEN (p=0.046).
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