Role of Mitochondrial Aldehyde Dehydrogenase in Human Melanoma

• Main Authors: Chien Che-Wei, 簡哲煒
• Other Authors: 江建平
• Format: Others
• Language: zh-TW
• Published: 2015
• Online Access: http://ndltd.ncl.edu.tw/handle/04745965893736574393

碩士 === 國防醫學院 === 生物化學研究所 === 103 === Skin cancer is one of the top ten cancer prevalence in Taiwan. Common skin cancer included basal cell carcinoma, squamous cell carcinoma and melanoma. Cutaneous melanoma is one of the most deadly form of cancer and therefore the effective regimen for melanoma therapy is still warranted. Recent large cohort studies showed that alcohol consumption is positively associated with the risk of cutaneous melanoma. Alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) are principle enzymes participated in alcohol metabolism. Mitochondrial aldehyde dehydrogenase (ALDH2) is the major enzyme for acetaldehyde oxidation in the second step. ALDH2 mRNA expression significantly decreased during melanoma progression by Gene Expression Omnibus (GEO) analysis. The aim of the study was to assess role of ALDH2 in melanoma and try to clarify the relationship of alcohol metabolism and cutaneous melanoma. We used purified class-specific antibody against ALDH2 to elucidate the cellular distribution of the protein in a human tissue microarray derived from 20 patients with common nevus (CN), 12 patients with dysplastic nevus (DN), and 80 patients with primary acral melanoma (AM).The relationships between AJCC TNM stage and immunostaining score of ALDH2 were also examined. Then we used three melanoma cell lines (A375, A2058 and MeWo) for studies of immunoblotting and immunocytochemistry. We compared the expressions of ALDH2, BRAFV600E, MEK and STAT3 phosphorylation before and after adding ALDH2 activator (alda-1) or inhibitor (cyanamide). By wound healing assay, we also observed the migration of melanoma cells in the present of alda-1 or cyanamide. The results showed that a statistically higher score for ALDH2 staining in CN (227 ± 10) than in DN (179 ± 10, p = 0.005) and AM (153 ± 16, p = 0.00001). No statistical differences in survival and no association between immunostaining of ALDH2 and other clinical parameters were demonstrated by regression testing. Genotyping result identified ALDH2*1/*1 in A375, A2058 and MeWo cells. Increasing expression of ALDH2 was noted after treating with BRAF inhibitor (vemurafenib). Decreased BRAFV600E and downstream MEK expressions were found after adding alda-1. Attenuated phosphorylation of STAT3 was observed by the effects of cyanamide/disulfiram. No obviously differences in migration ability by treating with alda-1and vermurafenib. In summary, the expression of ALDH2 attenuated orderly from CN, DN, and AM. Similar effects of alda-1 and vermurafenib were observed in A375 cell model. Change of ALDH2 was possibly an early event in melanoma pathogenesis and activation of ALDH2 might become a supplementary therapy in treating melanoma.