Igarashi Kentaro, Kawaguchi Kei, Kiyuna Tasuku, Miyake Kentaro, Murakami Takashi, Yamamoto Norio, Hayashi Katsuhiro, Kimura Hiroaki, Miwa Shinji, Tsuchiya Hiroyuki, Hoffman Robert M
AntiCancer, Inc., San Diego, CA, U.S.A.
Department of Surgery, University of California, San Diego, CA, U.S.A.
Anticancer Res. 2017 Sep;37(9):4807-4812. doi: 10.21873/anticanres.11887.
Methionine dependence may be the only known general metabolic defect in cancer. In order to exploit methionine dependence for therapy, our laboratory previously cloned L-methionine α-deamino-γ-mercaptomethane lyase [EC 4.4.1.11]) (recombinant methioninase [rMETase]), which was subsequently tested in mouse models of various types of human tumors. The present study aimed to investigate the efficacy of rMETase on human osteosarcoma cells in vitro and in vivo.
Human osteosarcoma cell lines 143B, HOS and SOSN2 were tested in vitro for survival during a 72-h exposure to rMETase using the WST-8 assay. Half-maximal inhibitory concentrations were calculated for in vitro efficacy experiments. 143B cells were orthotopically transplanted into the tibia of nude mice. Mouse models were randomized into the following groups 1 week after transplantation: Group 1, untreated control; Group 2, cisplatinum (CDDP) [intraperitoneal (i.p.) injection at 6 mg/kg weekly, for 3 weeks], positive control; Group 3, rMETase, 100 units/mouse i.p. daily, for 21 days. Tumor sizes and body weight were measured with calipers and a digital balance once per week, respectively.
rMETase significantly inhibited osteosarcoma cell growth, in a dose-dependent manner, in vitro. Both CDDP and rMETase treatment significantly inhibited tumor volume compared to untreated control mice at 5 weeks after initiation. Tumor volumes were as follows: Group 1, untreated, control: 1808.2 ± 344 mm; Group 2, CDDP: 1102.2 ± 316 mm, p=0.0008 compared to untreated control; Group 3, rMETase: 884.8 ± 361 mm, p=0.0001 compared to untreated control. There were no animal deaths in any group. The body weight of mice was not significantly different between any group.
rMETase showed promising efficacy against osteosarcoma, a recalcitrant tumor type. Future studies will investigate the efficacy of rMETase on patient-derived orthotopic xenograft (PDOX) models of osteosarcoma as a bridge to testing rMETase in the clinic.
蛋氨酸依赖性可能是癌症中唯一已知的普遍代谢缺陷。为了利用蛋氨酸依赖性进行治疗，我们实验室先前克隆了L-蛋氨酸α-脱氨基-γ-巯基甲烷裂解酶[EC 4.4.1.11]（重组蛋氨酸酶[rMETase]），随后在各种类型的人类肿瘤小鼠模型中进行了测试。本研究旨在调查rMETase在体外和体内对人骨肉瘤细胞的疗效。
使用WST-8法在体外测试人骨肉瘤细胞系143B、HOS和SOSN2在暴露于rMETase 72小时期间的存活率。计算体外疗效实验的半数抑制浓度。将143B细胞原位移植到裸鼠的胫骨中。移植1周后将小鼠模型随机分为以下几组：第1组，未治疗的对照组；第2组，顺铂（CDDP）[每周腹腔内（i.p.）注射6 mg/kg，共3周]，阳性对照组；第3组，rMETase，每天100单位/小鼠腹腔注射，共21天。每周分别用卡尺和数字天平测量肿瘤大小和体重。
rMETase在体外以剂量依赖性方式显著抑制骨肉瘤细胞生长。与未治疗的对照小鼠相比，在开始治疗5周后，CDDP和rMETase治疗均显著抑制肿瘤体积。肿瘤体积如下：第1组，未治疗的对照组：1808.2±344立方毫米；第2组，CDDP：1102.2±316立方毫米，与未治疗的对照组相比p = 0.0008；第3组，rMETase：884.8±361立方毫米，与未治疗的对照组相比p = 0.0001。任何组均无动物死亡。各组小鼠体重无显著差异。
rMETase对骨肉瘤（一种难治性肿瘤类型）显示出有前景的疗效。未来的研究将调查rMETase对骨肉瘤患者来源的原位异种移植（PDOX）模型的疗效，作为在临床中测试rMETase的桥梁。
