Miyagawa Tomoyuki, Saito Hajime, Minamiya Yoshihiro, Mitobe Kazutaka, Takashima Shinogu, Takahashi Naoko, Ito Aki, Imai Kazuhiro, Motoyama Satoru, Ogawa Junichi
Department of Surgery, Division of Thoracic Surgery, Akita University School of Medicine, 1-1-1 Hondo, Akita, 010-8543, Japan.
Int J Clin Oncol. 2014 Aug;19(4):722-30. doi: 10.1007/s10147-013-0606-x. Epub 2013 Aug 15.
Heat shock protein (Hsp) 90 is a key regulator of various oncogene products and cell-signaling molecules, while Hsp70 protects against heat-induced apoptosis. We previously described a system in which hyperthermia was produced using thermosensitive ferromagnetic particles (FMPs) with a Curie temperature (T c) of 43 °C to mediate automatic temperature control, and demonstrated its antitumor effect in a mouse melanoma model. In the present study, the antitumor effects of combining Hsp90 inhibitor (17DMAG) and Hsp70 inhibitor (quercetin) with FMP-mediated hyperthermia were examined.
Expressions of Hsp90/70 and Akt were evaluated using Western blotting in vitro. In an in vivo study, melanoma cells were subcutaneously injected into the backs of C57BL/6 mice. FMPs were then injected into the resultant tumors, and the mice were divided into groups treated with quercetin and/or 17DMAG with/without hyperthermia. When exposed to a magnetic field, the temperature of tissues containing FMPs increased and stabilized at the T c. The TUNEL method was used to determine whether hyperthermia induced apoptosis within tumors.
In the group pretreated with hyperthermia + quercetin + 17DMAG, Akt expression was reduced in vitro, the incidence of apoptosis within tumors was greater, and tumor growth was significantly suppressed 20 days after FMP injection in vivo, compared with other treatment groups. The survival rates among tumor-bearing mice observed for a period of 40 days were significantly higher in the hyperthermia + quercetin + 17DMAG group.
Combining Hsp90/70 inhibition with hyperthermia appears to increase their antitumor effects. Thus, the combination of FMP-mediated, self-regulating hyperthermia with Hsp90/70 inhibition has important implications for cancer treatment.
热休克蛋白（Hsp）90是多种癌基因产物和细胞信号分子的关键调节因子，而Hsp70可保护细胞免受热诱导的凋亡。我们之前描述了一种利用居里温度（Tc）为43°C的热敏铁磁颗粒（FMP）产生热疗以介导自动温度控制的系统，并在小鼠黑色素瘤模型中证明了其抗肿瘤作用。在本研究中，检测了将Hsp90抑制剂（17DMAG）和Hsp70抑制剂（槲皮素）与FMP介导的热疗联合应用的抗肿瘤效果。
在体外使用蛋白质免疫印迹法评估Hsp90/70和Akt的表达。在体内研究中，将黑色素瘤细胞皮下注射到C57BL/6小鼠的背部。然后将FMP注射到形成的肿瘤中，并将小鼠分为用槲皮素和/或17DMAG治疗且伴有或不伴有热疗的组。当暴露于磁场时，含有FMP的组织温度升高并在Tc处稳定。采用TUNEL法确定热疗是否诱导肿瘤内凋亡。
与其他治疗组相比，在热疗+槲皮素+17DMAG预处理组中，体外Akt表达降低，肿瘤内凋亡发生率更高，在体内FMP注射后20天肿瘤生长受到显著抑制。热疗+槲皮素+17DMAG组荷瘤小鼠观察40天的生存率显著更高。
将Hsp90/70抑制与热疗联合应用似乎可增强其抗肿瘤效果。因此，FMP介导的自调节热疗与Hsp90/70抑制的联合应用对癌症治疗具有重要意义。
