Adjei A A, Budihardjo I I, Rowinsky E K, Kottke T J, Svingen P A, Buckwalter C A, Grochow L B, Donehower R C, Kaufmann S H
The Johns Hopkins Oncology Center, Baltimore, Maryland 21287, and Division of Oncology Research, Mayo Clinic, Rochester, Minnesota 55905, USA.
Clin Cancer Res. 1997 May;3(5):761-70.
Pyrazoloacridine (PA), an acridine congener that has shown selective toxicity in solid tumor cells, full activity against noncycling and hypoxic cells, and promising activity in a recent Phase I trial, is currently undergoing Phase II testing as a solid tumor-selective agent. In the present study, clonogenic assays were used to examine the cytotoxic effects when PA was combined with other antineoplastic agents in A549 human non-small cell lung cancer cells in vitro. Data were analyzed by the median effect method. Combinations of PA with antimetabolites (5-fluorouracil, methotrexate, and cytarabine) or with antimicrotubule agents (paclitaxel and vincristine) failed to exhibit synergy. Likewise, combinations of PA with alkylating agents (melphalan, 4-hydroperoxycyclophosphamide) were less than additive. In contrast, the combination of PA and cisplatin exhibited cytotoxicity that was additive or synergistic over a broad range of clinically achievable concentrations. Moreover, studies involving sequential exposure to PA and cisplatin revealed a synergistic interaction when cells were exposed to the two agents in either sequence. Synergy was likewise observed with this combination in T98G human glioblastoma cells and HCT8 human intestinal adenocarcinoma cells as well as AuxB1 hamster ovary cells. Flow microfluorimetry revealed that PA caused arrest of A549 cells in G1 and G2 phases of the cell cycle, providing a potential explanation for the antagonism between PA and antimetabolites or antimicrotubule agents. Further studies revealed that PA inhibited removal of platinum-DNA adducts in A549 cells in a dose-dependent fashion, with almost complete inhibition occurring at 1 microM PA. These latter observations provide a mechanistic explanation for the synergy between PA and cisplatin and suggest that this combination warrants further preclinical and clinical investigation.
吡唑并吖啶（PA）是一种吖啶同类物，已显示出对实体瘤细胞具有选择性毒性，对非增殖细胞和缺氧细胞具有完全活性，并且在最近的I期试验中表现出有前景的活性，目前正在作为实体瘤选择性药物进行II期试验。在本研究中，采用克隆形成试验来检测PA与其他抗肿瘤药物联合应用时对体外培养的A549人非小细胞肺癌细胞的细胞毒性作用。数据采用中位效应法进行分析。PA与抗代谢药物（5-氟尿嘧啶、甲氨蝶呤和阿糖胞苷）或与抗微管药物（紫杉醇和长春新碱）联合应用均未表现出协同作用。同样，PA与烷化剂（美法仑、4-氢过氧环磷酰胺）联合应用时作用小于相加作用。相比之下，PA和顺铂联合应用在广泛的临床可达到浓度范围内表现出相加或协同的细胞毒性。此外，涉及先后暴露于PA和顺铂的研究表明，当细胞以任何顺序暴露于这两种药物时均显示出协同相互作用。在T98G人胶质母细胞瘤细胞、HCT8人肠腺癌细胞以及AuxB1仓鼠卵巢细胞中，该联合用药同样观察到协同作用。流式细胞荧光测定法显示，PA导致A549细胞在细胞周期的G1期和G2期停滞，这为PA与抗代谢药物或抗微管药物之间的拮抗作用提供了一种潜在解释。进一步研究表明，PA以剂量依赖方式抑制A549细胞中铂-DNA加合物的清除，在1μM PA时几乎完全抑制。这些后期观察结果为PA和顺铂之间的协同作用提供了一种机制解释，并表明该联合用药值得进一步进行临床前和临床研究。
