Vikhanskaya F, Vignati S, Beccaglia P, Ottoboni C, Russo P, D'Incalci M, Broggini M
Department of Oncology, Istituto di Ricerche Farmacologiche Mario Negri, Milan, Italy.
Exp Cell Res. 1998 May 25;241(1):96-101. doi: 10.1006/excr.1998.4018.
Paclitaxel-induced cytotoxicity, cell cycle perturbation, and apoptosis were determined in a human ovarian cancer cell line expressing wt p53 (A2780) and in a subclone (A2780/E6) obtained upon transfection with the product of the E6 gene of the human papilloma virus HPV16. The inactivation of wt p53 in A2780/E6 was verified by measuring the inability of the clone to induce p53 and p21 expression after paclitaxel treatment. The p53-negative clone (A2780/E6) was approximately 50-fold more sensitive to paclitaxel than wt p53-expressing A2780 cells. This increased sensitivity was related to the ability of paclitaxel to induce a strong arrest of cells in the G2/M phase of the cell cycle in A2780/E6 but not in A2780 cells. This different cell cycle arrest was accompanied by increased frequency of paclitaxel-induced p53-independent apoptosis. Initial studies on proteases activation tend to exclude a direct role of ICE and CPP32 in the induction of apoptosis in these cells and show a paclitaxel-dependent increase in FLICE levels, whose biological relevance is however at present not defined.
在表达野生型p53的人卵巢癌细胞系（A2780）以及用人类乳头瘤病毒HPV16的E6基因产物转染后获得的亚克隆（A2780/E6）中，测定了紫杉醇诱导的细胞毒性、细胞周期扰动和细胞凋亡。通过测量该克隆在紫杉醇处理后无法诱导p53和p21表达，证实了A2780/E6中野生型p53的失活。p53阴性克隆（A2780/E6）对紫杉醇的敏感性比表达野生型p53的A2780细胞高约50倍。这种敏感性增加与紫杉醇在A2780/E6细胞周期的G2/M期诱导细胞强烈停滞的能力有关，而在A2780细胞中则不然。这种不同的细胞周期停滞伴随着紫杉醇诱导的不依赖p53的细胞凋亡频率增加。对蛋白酶激活的初步研究倾向于排除ICE和CPP32在这些细胞凋亡诱导中的直接作用，并显示FLICE水平在紫杉醇作用下增加，但其生物学相关性目前尚不清楚。
