原子力显微镜观测紫外线诱导的K562肿瘤细胞DNA损伤

利用彗星电泳检测出UVB、UVC短时间照射会使肿瘤细胞的DNA发生断裂,而长时间照射之后彗星电泳无法检测到碎片,推测可能是由于DNA分子交联的原因1],国内外尚无定论.为了更直观的研究这种现象,提取了UVB,UVA照射后K562细胞的DNA,并调节到合适的浓度在原子力显微镜下观测.实验结果表明UVB对K562肿瘤细胞DNA损伤的影响呈现时间/剂量效应,较短时间照射主要产生DNA的链断裂,较长时间辐射则主要产生DNA链的交联.UVC对K562肿瘤细胞DNA的损伤大于UVB.UVC短时照射即可引起DNA的断裂和交联,较长时间辐射主要产生交联和一些断裂;长时间照射不但产生大量交联,同时有大量断裂产生,并发生凝缩和缠绕等结构破坏.

Observation of the DNA Extracted from K562 Cells Exposed in Ultraviolet Light by Atomic Force Microscopy

The partner of the laboratory that the author stayed use the comet assay detect UVB,UVC radiation cause the broken of DNA in a short period. But after a long time the comet assay could not detect the phenomenon, we suppose that results was due to the DNA molecules cross-linked. In order to explain this phenomenon much more directly, and also give a correct model of DNA observation, DNA from the K562 cells was extracted that exposed in the UVB, UVC. The result indicatd that DNA damage increase as the dose of UVB, UVC increasing. In a short time, some of DNA of K562 cells exposed in UVB appeared to break to fracture. After a long time, majority of DNA appeaed to be cross-linking. UVB affected on DNA was much greater than UVB. Majority of DNA of K562 cells exposed in UVC for a short time appear to break and cross-link.Thus, it proves that long time exposure cause DNA molecules appear to winding and condensation, with other DNA damage.