Basic studies on combination of new hypoxic cell sensitizers and intraoperative radiotherapy for unresectable pancreatic cancer

我们研究了裸鼠移植的人胰腺癌细胞的放射敏感性和缺氧部分，以及一种新的缺氧细胞放射增敏剂多硝唑对它们的影响。虽然日本正在进行多硝唑联合术中放疗治疗局部不可切除胰腺癌的临床研究，但这些问题的数据报道很少。体外使用4种已建立的人胰腺癌细胞系（SUIT-2、PANC-1、MIA PaCa-2和BxPC-3）和小鼠SCCVII肿瘤细胞（用于比较）。在好氧或缺氧照射前和照射中分别用0.4或1 mM多硝唑处理45 min，用集落法测定细胞存活率。在体内，背部携带胰腺癌（约200 mg）的Balb/c裸小鼠，在颈椎脱位后，在没有身体约束或麻醉的情况下，或在静脉注射100 mg/kg （0.4 mmol/kg）或250 mg/kg （1 mmol/kg）的多硝唑后20分钟进行全身照射。辐照后，进行体内外实验。用配对生存曲线法估计缺氧分数。在体外放射敏感性方面，四种胰腺癌细胞系没有共同的特征。在体外，多硝唑在有氧条件下无增敏作用，但在缺氧条件下，其对4种胰腺癌细胞系的增敏增强比（SER）在0.4 mM时为1.25 ~ 1.3，在1 mM时为1.4 ~ 1.55。这些SERs与SCCVII细胞中获得的SERs相似。体内缺氧比例在SUIT-2中为20% (95% CI, 11-38%)，在PANC-1中为14%(6.5-28%)，在MIA PaCa-2中为10%(5.9-16%)，在BxPC-3中为27%（15-46%）。100 mg/kg剂量下多硝唑的SER为1.15 ~ 1.3,250 mg/kg剂量下SER为1.35 ~ 1.45。总之，4例异种移植胰腺癌的缺氧比例为10-27%（平均：18%）。这些结果可能提示在不可切除的胰腺癌术中放疗中使用低氧细胞增敏剂是合理的。多硝唑对所有胰腺癌细胞系均有明确的体内外作用，但SERs不够高。剂量递增应在未来的临床研究中进行调查。少

We investigated the radiosensitivity and hypoxic fraction of human pancreatic cancer cells xenografted in nude mice, and the efficacy of a new hypoxic cell radiosensitizer doranidazole against them. Although a clinical study of doranidazole in combination with intraoperative radiotherapy is ongoing in Japan for localized unresectable pancreatic cancer, few data have been reported on these issues.In vitro, four established human pancreatic cancer cell lines (SUIT-2, PANC-1, MIA PaCa-2 and BxPC-3) and murine SCCVII tumor cells (for comparison) were used. These cells were treated with 0.4 or 1 mM doranidazole for 45 min prior to and during aerobic or hypoxic irradiation, and the cell survival was determined using the colony assay. In vivo, Balb/c nude mice bearing the pancreatic cancers (about 200 mg) on their backs received whole-body irradiation either after cervical dislocation, without physical restraint or anesthesia, or 20 min after intravenous injection of 100 mg/kg (0.4 mmol/kg) o … More r 250 mg/kg (1 mmol/kg) of doranidazole. Following irradiation, the in vivo-in vitro assay was performed. The hypoxic fraction was estimated by the paired survival curve method.Regarding in vitro radiosensitivity, there were no characteristics common to the four pancreatic cancer cell lines. In vitro, doranidazole had no sensitizing effect under aerobic conditions, but under hypoxic conditions, its sensitizer enhancement ratio (SER) was 1.25-1.3 at 0.4 mM and 1.4-1.55 at 1 mM against the four pancreatic cancer cell lines. These SERs were similar to those obtained in SCCVII cells. In vivo, the hypoxic fraction was 20% (95% CI, 11-38%) in SUIT-2, 14% (6.5-28%) in PANC-1, 10% (5.9-16%) in MIA PaCa-2, and 27% (15-46%) in BxPC-3 tumors. The SER of doranidazole was 1.15-1.3 at the dose of 100 mg/kg and 1.35-1.45 at 250 mg/kg.In summary, the four xenografted pancreatic cancers had hypoxic fractions of 10-27% (mean : 18%). These results might suggest that the use of a hypoxic cell sensitizer is reasonable in intraoperative radiotherapy for unresectable pancreatic cancer. Doranidazole had definite in vitro and in vivo effects on all pancreatic cancer cell lines, but the SERs were not high enough. Dose escalation should be investigated in future clinical studies. Less