Shen H, Schultz M, Kruh G D, Tew K D
Department of Pharmacology, Fox Chase Cancer Center, 7701 Burholme Avenue, Philadelphia, PA 19111, USA.
Biochim Biophys Acta. 1998 Jul 23;1381(2):131-8. doi: 10.1016/s0304-4165(98)00020-8.
Acquired resistance to adriamycin (ADR) in an HL60 cell line is shown to be accompanied by an increase in DNA-dependent protein kinase catalytic subunit (DNA-PKcs) at both the protein and mRNA levels (15-20-fold) and an overall 3-fold increase in DNA-PK enzyme activity. The other components of the DNA-PK Ku autoantigen complex, Ku70 and Ku80, were 3-fold increased and unchanged, respectively. Time dependent repair of ADR-induced DNA damage was measured by the neutral comet assay and found to be more efficient in the drug resistant cell line (HL60/ADR). Antisense RNA transfection reduced the protein expression of DNA-PKcs to 50% in HL60/ADR and partially reversed drug resistance. A fibroblast cell line from a severe combined immunodeficient (SCID) mouse was deficient in functional DNA-PKcs and showed increased sensitivity to ADR and other DNA damaging agents compared to wild type. These studies demonstrate that alteration in DNA-PK can contribute to chronic stress response leading to acquired drug resistance. The overexpression of DNA-PK is thus shown to be a novel cellular adaptation mechanistically contributing to the resistance of cancer cells to the anthracycline drug adriamycin, and as such, may have implications for its therapeutic use.
在一种HL60细胞系中，对阿霉素（ADR）获得性耐药表现为DNA依赖性蛋白激酶催化亚基（DNA-PKcs）在蛋白质和mRNA水平均增加（15 - 20倍），且DNA-PK酶活性总体增加3倍。DNA-PK Ku自身抗原复合物的其他成分Ku70和Ku80分别增加3倍和未发生变化。通过中性彗星试验测量阿霉素诱导的DNA损伤的时间依赖性修复，发现其在耐药细胞系（HL60/ADR）中更有效。反义RNA转染使HL60/ADR中DNA-PKcs的蛋白质表达降低至50%，并部分逆转了耐药性。来自严重联合免疫缺陷（SCID）小鼠的成纤维细胞系缺乏功能性DNA-PKcs，与野生型相比，对阿霉素和其他DNA损伤剂表现出更高的敏感性。这些研究表明，DNA-PK的改变可导致慢性应激反应，进而导致获得性耐药。因此，DNA-PK的过表达被证明是一种新的细胞适应机制，在机制上有助于癌细胞对蒽环类药物阿霉素产生耐药性，因此，可能对其治疗应用具有重要意义。
