Elliott M J, Stribinskiene L, Lock R B
The Henry Vogt Cancer Research Institute, Department of Medicine, University of Louisville, Kentucky 40202, USA.
Cancer Chemother Pharmacol. 1998;41(6):457-63. doi: 10.1007/s002800050767.
A reduced capacity for apoptosis induction is considered to play a significant role both in the development of malignancy and in tumor cell resistance to chemotherapeutic drugs. The Bcl-2 oncoprotein inhibits apoptosis induced by antitumor agents at a point downstream of drug-target interactions. Stable expression of Bcl-2 in the human epithelial tumor (HeLa) cell line results in inhibition of apoptosis following exposure to the topoisomerase II poison, etoposide. However, Bcl-2 is unable to enhance clonogenic survival as a result of alternate pathways to reproductive death induced by the drug.
The purpose of this study was to further investigate the role of Bcl-2 in human epithelial tumor cell drug resistance using 5-fluoro-2'-deoxyuridine, staurosporine, and doxorubicin, in addition to etoposide.
The ability of Bcl-2 to enhance clonogenic cell survival was studied by colony-forming assays, while delay of cell death induction was assessed by trypan blue viability measurements. The proportion of apoptotic cells was measured by morphological criteria, as well as detection of apoptotic DNA fragmentation using the terminal deoxynucleotidyl transferase assay.
Despite profound inhibition to loss of plasma membrane integrity for all agents tested, Bcl-2 was only able to significantly increase clonogenic survival following exposure to 5-fluoro-2'-deoxyuridine and staurosporine, but not following exposure to etoposide or doxorubicin. Furthermore, the time-course of apoptosis induction following exposure of HeLa cells to equitoxic concentrations of staurosporine and etoposide was profoundly different.
These results indicate that Bcl-2 enhances clonogenic survival of human epithelial tumor cells in an agent-specific fashion, which may be determined by the initial cytotoxic lesion induced by a particular drug.
凋亡诱导能力降低被认为在恶性肿瘤的发展以及肿瘤细胞对化疗药物的耐药性中都起着重要作用。Bcl-2癌蛋白在药物-靶点相互作用下游的某一点抑制抗肿瘤药物诱导的凋亡。人上皮肿瘤（HeLa）细胞系中Bcl-2的稳定表达导致暴露于拓扑异构酶II毒药依托泊苷后凋亡受到抑制。然而，由于药物诱导的生殖死亡的替代途径，Bcl-2无法提高克隆形成存活率。
本研究的目的是除依托泊苷外，使用5-氟-2'-脱氧尿苷、星形孢菌素和阿霉素进一步研究Bcl-2在人上皮肿瘤细胞耐药性中的作用。
通过集落形成试验研究Bcl-2增强克隆形成细胞存活的能力，同时通过台盼蓝活力测量评估细胞死亡诱导的延迟。通过形态学标准以及使用末端脱氧核苷酸转移酶测定法检测凋亡DNA片段化来测量凋亡细胞的比例。
尽管对所有测试药物的质膜完整性丧失有显著抑制作用，但Bcl-2仅在暴露于5-氟-2'-脱氧尿苷和星形孢菌素后能够显著提高克隆形成存活率，而在暴露于依托泊苷或阿霉素后则不能。此外，HeLa细胞暴露于等毒性浓度的星形孢菌素和依托泊苷后凋亡诱导的时间进程有很大差异。
这些结果表明，Bcl-2以药物特异性方式增强人上皮肿瘤细胞的克隆形成存活率，这可能由特定药物诱导的初始细胞毒性损伤决定。
