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将人类肝癌细胞,7703株,悬于PBS中,与血卟啉一起在37℃保温一小时;然后用340—370nm的紫外线在40℃照射32分钟(～3.94×10~(-2)J/cm~2·min)用Fornace和Kohn的与蛋白酶处理相结合的碱液洗脱法测定细胞DNA的单链断裂和交联。得到三个结果:(1)在细胞与血卟啉(3.1—50.0μg/ml)一起保温的一小时中,发生DNA降解。(2)血卟啉(50μg/ml)的光敏化作用会使DNA交联作用增多1倍(P<0.01)。(3)在血卟啉光敏化作用所产生的交联物中的DNA,有87％是与蛋白质交联的。由于血卟啉促进细胞DNA交联作用尚未见于以往文献,作者认为在考虑用血卟啉作敏化剂的癌的光辐射治疗中细胞杀伤机制时,不能忽视这种现象。
Human hepatoma cells, 7703 strains, were suspended in PBS and incubated with hematoporphyrin at 37°C for one hour; then irradiated with ultraviolet rays at 340-370 nm for 32 minutes at 40°C (-3.94×10-2 J/ Cm~2·min) Single-strand breaks and cross-links of DNA in cells were determined by alkaline elution with Fornace and Kohn in combination with protease treatment. Three results were obtained: (1) DNA degradation occurred within one hour of incubation of cells with hematoporphyrin (3.1-50.0 μg/ml). (2) The photosensitization of hematoporphyrin (50μg/ml) increased DNA cross-linking by 1 fold (P<0.01). (3) Eighty-seven percent of the DNA in the crosslinks produced by the photosensitizing effect of hematoporphyrin was cross-linked to proteins. Since hematoporphyrins have not promoted DNA cross-linking in previous literature, the authors believe that this phenomenon cannot be ignored when considering the mechanism of cell killing in phototherapy of cancers using hematoporphyrins as sensitizers.