Yin Ming-biao, Hapke Gunnar, Wu Jiaxi, Azrak Rami G, Frank Cheryl, Wrzosek Carol, Rustum Youcef M
Department of Pharmacology and Therapeutics, Grace Cancer Drug Center, Roswell Park Cancer Institute, Buffalo, NY 14263, USA.
Biochem Biophys Res Commun. 2002 Jul 12;295(2):435-44. doi: 10.1016/s0006-291x(02)00683-6.
A novel karenitecin, BNP1350, is a topoisomerase I-targeting anticancer agent with significant antitumor activity in vitro and in vivo. A BNP1350-resistant human head and neck carcinoma A253 cell line, denoted A253/BNPR, was developed. The A253/BNPR cell line was approximately 9-fold resistant to BNP1350 and 4-fold cross-resistant to another topoisomerase I inhibitor SN-38, the active metabolite of irinotecan. After drug treatment with equimolar concentrations of BNP1350 (0.7 microM) for 2h, activation of the DNA double-strand break repair protein complexes was similar in the two cell lines, suggesting that DNA dsb repair is not attributable to resistance to BNP1350 in the A253/BNPR cells. Cell cycle analysis indicates that the A253 cell line accumulated primarily in S phase, but G(2) phase accumulation was observed in the A253/BNPR cell line at 48 h after drug removal. Elevated chk1 phosphorylation at Ser(345) following DNA damage induced by BNP1350 was accompanied by G(2) accumulation in the A253/BNPR cell line, while exposure to equimolar concentrations of BNP1350 (0.7 microM) induced S-phase arrest and no increased phosphorylation of chk1 at Ser(345) in the A253 cell line. Under the same conditions, increased chk1 activity was observed in the A253/BNPR cell line, but not in the A253 cell line. Moreover, stimulated binding of 14-3-3 proteins to chk1 was observed in BNP1350-treated A253/BNPR cells. To confirm relationship between chk1 expression/phosphorylation and drug resistance to topo I poisons, we examined the effects of chk1 or chk2 antisense oligonucleotides on the cellular growth inhibition. Chk1 antisense oligonucleotide can sensitize the A253/BNPR cells to killing by topo I inhibitor BNP1350, but no significant sensitization of BNP1350-induced growth inhibition was observed in the drug-sensitive cell line. Chk2 antisense oligonucleotide has only a small sensitization effect on BNP1350-induced growth inhibition in both cell lines. The data indicate that the chk1 signaling pathways that mediate cell cycle checkpoint are associated with cellular resistance to BNP1350 in the A253/BNPR cell line.
一种新型的卡瑞尼特辛BNP1350是一种靶向拓扑异构酶I的抗癌药物，在体外和体内均具有显著的抗肿瘤活性。我们构建了一种对BNP1350耐药的人头颈癌A253细胞系，命名为A253/BNPR。A253/BNPR细胞系对BNP1350的耐药性约为9倍，对另一种拓扑异构酶I抑制剂SN-38（伊立替康的活性代谢产物）有4倍的交叉耐药性。用等摩尔浓度（0.7微摩尔）的BNP1350处理细胞2小时后，两种细胞系中DNA双链断裂修复蛋白复合物的激活情况相似，这表明DNA双链断裂修复并非A253/BNPR细胞对BNP1350耐药的原因。细胞周期分析表明，A253细胞系主要停滞在S期，但在去除药物48小时后，A253/BNPR细胞系出现G2期停滞。BNP1350诱导DNA损伤后，A253/BNPR细胞系中Ser(345)位点的chk1磷酸化水平升高，并伴有G2期停滞，而用等摩尔浓度（0.7微摩尔）的BNP1350处理A253细胞系时，诱导S期停滞，且Ser(
