Further studies on the interaction of nonpolyglutamatable aminopterin analogs with dihydrofolate reductase and the reduced folate carrier as determinants of in vitro antitumor activity

Thirteen structural analogs of the potent nonpolyglutamatable dihydrofolate reductase inhibitor N(alpha)-(4-amino-4-deoxypteroyl)-N(delta)-hemiphthaloyl-L-ornithine (PT523) with modifications in the side chain, the para-aminobenzoyl moiety, or the 9,10-bridge were evaluated for the ability to inhibit human recombinant dihydrofolate reductase (DHFR), to utilize the reduced folate carrier (RFC) for influx, and to inhibit the growth of CCRF-CEM human leukemia cells in culture. In spectrophotometric assays of the kinetics of the reduction of dihydrofolate by DHFR in the presence of NADPH, these compounds had K(i) values ranging from 0.2 to 1.3pM, and thus were not greatly different in potency from the parent drug PT523. By comparison, the K(i) values of aminopterin (AMT), methotrexate (MTX), and 10-ethyl-10-deazaaminopterin (EDX) were 3.7, 4.8, and 11pM. In assays of competitive inhibition of [3H]MTX influx into CCRF-CEM cells, the K(i) values ranged from 0.21 to 7.3 micro M, as compared with 0.71, 5.4, and 1.1 micro M for PT523, AMT, and EDX. The K(t) for MTX was also re-analyzed and found to be 4.7 micro M, in better agreement with the literature than our previously reported value of 7.1 micro M. The IC(50) values of these compounds as inhibitors of the growth of CCRF-CEM cells after 72hr of drug exposure ranged from 0.53 to 55nM, and were qualitatively consistent with the other results.     

NDV7793体外激活的小鼠单核巨噬细胞(MΦ)对小鼠肝癌细胞的杀伤作用及其机制

 目的
初步研究NDV7793激活的小鼠单核巨噬细胞（MΦ）对小鼠肝癌Novikoff细胞的杀伤作用,并探讨其杀伤机制与TNF-
α和TRAIL的关系。 方法从腹腔分离6周龄BALB/C小鼠MΦ, 用NDV7793于体外刺激小鼠MΦ,以ELISA分别测定
NDV7793刺激小鼠MΦ后产生的TNF-α及TRAIL水平;NDV7793体外刺激MΦ后,与小鼠肝癌Novikoff细胞混合培养,
以LDH微量释放法测定小鼠MΦ对小鼠肝癌Novikoff细胞的杀伤效应。同时设立3组实验对照组：IFN-β阳性对照组
、紫外线灭活NDV（UV-NDV）对照组以及空白对照组。 结果与3个对照组相比,NDV7793在体外能提高MΦ分泌TNF-
α、TRAIL的水平;NDV体外刺激后的小鼠MΦ能杀伤小鼠肝癌Novikoff细胞。结论NDV7793在体外能激活小鼠MΦ,
小鼠MΦ被NDV7793刺激后,对小鼠肝癌Novikoff细胞的杀伤作用增强,NDV激活后的小鼠MΦ对小鼠肝癌Novikoff细
胞的杀伤机制可能与TNF-α和TRAIL有关。     

新城疫病毒7793株对人结肠癌细胞的杀伤作用

目的:研究新城疫病毒NDV7793对人结肠癌细胞的体外杀伤作用,为结肠癌的生物疗法奠定基础。方法:通过蚀斑实验纯化病毒并测定纯化的NDV7793株的感染力;用乳酸脱氢酶微量释放法测定纯化病毒对人LoVo和Ls174t结肠癌细胞株的杀伤作用并且通过血凝实验测定病毒在不同细胞中的增殖力。结果:NDV7793在感染细胞96h后出现直径约为0.5mm左右的空斑,PFU为1.25×107个/ml,为弱毒株;NDV7793对LoVo和Ls174t人结肠癌细胞株有明显的杀伤作用,而且杀伤作用的强度与病毒作用的时间和病毒的浓度呈正相关的关系;NDV7793可以在肠癌细胞中生长复制,该病毒株在人结肠癌细胞株LoVo的复制能力强于Ls174t。结论:NDV7793具有较强的选择性杀伤人结肠癌细胞的作用,且为弱毒株,这株病毒具备肿瘤生物治疗的潜能。     

新城疫病毒7793株对人结肠癌细胞的杀伤作用

目的：研究新城疫病毒NDV7793对人结肠癌细胞的体外杀伤作用,为结肠癌的生物疗法奠定基础。方法：通过蚀斑实验纯化病毒并测定纯化的NDV7793株的感染力;用乳酸脱氢酶微量释放法测定纯化病毒对人LoVo和Ls174t结肠癌细胞株的杀伤作用并且通过血凝实验测定病毒在不同细胞中的增殖力。结果：NDV7793在感染细胞96h后出现直径约为0.5mm左右的空斑,PFU为1.25×107个/ml,为弱毒株;NDV7793对LoVo和Ls174t人结肠癌细胞株有明显的杀伤作用,而且杀伤作用的强度与病毒作用的时间和病毒的浓度呈正相关的关系;NDV7793可以在肠癌细胞中生长复制,该病毒株在人结肠癌细胞株LoVo的复制能力强于Ls174t。结论：NDV7793具有较强的选择性杀伤人结肠癌细胞的作用,且为弱毒株,这株病毒具备肿瘤生物治疗的潜能。