| Abstract: | 斑螫素, ( Cantharidin; exo,exo-2,3-dimethy-7-oxabicyclo [ 2,2,1 ] heptane-2,3-dicarboxylic anhydride)，在許多研究中指出具有抑制癌細胞增殖的作用，可能影響到的分子機制有p53 dependent mechanism，它同時也可抑制蛋白磷酸1 (protein phosphatases 1，PP1)和蛋白磷酸2A (protein phosphatases 2A)，由於產生氧化應激(Oxidative stress)，所以經由comet assay可以見到單股和雙股去氧核醣核酸受損情形發生，但就以分子生物學的角度來看其抗癌機轉尚未完全明瞭。我們利用斑螫素及斑螫素衍生物去做為以光觸發作為切割去氧核醣核酸的試劑，經由超螺旋結構的去氧核醣核酸加上化合物以紫外光線 ( 352-nm ) 照射去確定化合物是否具有切割去氧核醣核酸的能力。結果發現斑螫素衍生物( 2,6-Dimethyl-4-[4-(6-methyl-benzothiazol-2-yl)-phenyl]-10-oxa-4-aza-tricyclo[5.2.1.02,6]decane-3,5-dione )在酸性情況下經由紫外光352 nm照射可作為好的去氧核醣核酸切割試劑，之後更進一步利用高解析電泳實驗分析，以Maxma-Gilbert實驗結果作為記號去確認化合物是否具有辨識去氧核醣核酸鹼基位置的特性，結果顯示，斑螫素衍生物，( 2,6-Dimethyl-4-[4-(6-methyl-benzothiazol-2-yl)-phenyl]-10-oxa-4-aza-tricyclo[5.2.1.02,6]decane-3,5-dione )，對於guanine這個鹼基位置具有較強之切割能力。
Previous studies indicated that cantharidin (exo-2,3-dimethy-7-oxabicyclo [ 2,2,1 ] heptane-2,3-dicarboxylic anhydride)could inhibit the proliferation of cancer cells via p53 dependent mechanism. It could also inhibit protein phosphatases 1(PP1) and protein phosphatases 2A( PP2A ). When cancer cell was treated with cantharidin, it could induce to produce oxidative stress. Oxidative stress would cause increments of single and double stand DNA damage. But the mechanism of anticancer is still not clear. Here, cantharidin and cantharidin derivatives could be served as photo-initiated DNA cleavage agents. We irradiated at λ=352 nm to see whether they have the ability to cleave the super-coiled DNA. The results displayed that the cantharidin derivatives ( 2,6-Dimethyl-4-[4-(6-methyl-benzothiazol-2-yl)-phenyl]-10-oxa-4-aza-tricyclo[5.2.1.02,6]decane-3,5-dione ) could cause DNA scission at acidic condition upon UV irradiation. Then, we used high-resolution gel electrophoresis to analyze the cleavage patterns. The Maxma-Gilbert sequencing data were served as sequence-specific or base-specific cleavage marks. The results indicated that cantharidin derivatives ( 2,6-Dimethyl-4-[4-(6-methyl-benzothiazol-2-yl)-phenyl]-10-oxa-4-aza-tricyclo[5.2.1.02,6]decane-3,5-dione ) have better ability of cleavage at the guanine site. |
