新型辐射增敏药CM对受照肝癌H_(22)细胞DNase作用的研究

STUOIES ON THE EFFECT OF A NEW RADIOSENSITIZER CM ON THE DNase ACTIVITY OF IRRADIATED HEPATIC TUMOR CELLS

本文报道了新型辐射增敏药甲硝唑氨酸(CM)及其与Ca^(+2)结合后对肝癌H_(22)细胞DNase作用,并观察了CM,CMCa及Ca^(+2)和三者分别对受30Gyγ线照射细胞DNase活力的影响。结果表明,CM浓度在10mmol/L以下对H_(22)细胞DNase有激活作用。以5mmol/L时激活作用最强,在5mmol/L以下随药物浓度的增加,激活作用随之增加,CM与Ca^(+2)结合成CMCa后对细胞DNase的激活作用与CM相似,两者无显著差别(p>0.05),CM、CMCa的这种激活作用与γ线照射后对DNase活力增高有叠加作用,而Ca^(+2)对受照或非受照H_(22)细胞DNase活力无明显的影响。上述结果表明,CM及其与Ca^(+2)结合成CMCa后无论对受照或非受照H_(22)细胞DNase均有激活作用。这种通过激活受照肿瘤细胞DNase叠加活力的增加、增强DNA破坏而提高肿瘤放疗效果,可能是其放疗作用的机制之一。

The effects of a new radiosensitizing compound-metronidazolamic acid(CM) and its Ca^(+2) chelation compound (CMCa) on the DNase activity of mouse he-patic tumor (H_(22)) cells were observed. The effects of CM, CMCa or Ca^(+2) at same mo-larity and their combination with γ-rays irradiation on DNase activity of H_(22) cellswere also observed respectively. The results showed that CM could activate the DNaseactivity to be increased as CM concentratiom increased below 5 mmol/L. The highestDNase activity was activated by CM at 5 mmol/L. The degree of activation betweenCM and CMCa had no significant differente (p>0.05), whereas free Ca^(+2) alone hadno effect. The activation of combined CM or CMCa and radiation groups were greaterthan that of each given independently (Fig. 3), they possessed a coordinate activation.However free Ca^(+2) still could not activate the DNase activity after γ-irradiation. Fromall the above results, it is suggested that CM or CMCa improved the tumor radiothe-rapeutic efficiency probable due to its activation the DNase activity of cancer cellswhich enhanced the DNA damage. It might be one of the radiosensitizing mechanismin tumor radiothorapy.