Newell K, Wood P, Stratford I, Tannock I
Department of Medical Biophysics, University of Toronto, Ontario, Canada.
Br J Cancer. 1992 Aug;66(2):311-7. doi: 10.1038/bjc.1992.262.
Cell killing can be achieved in an acidic environment in tissue culture (medium pH less than 7.0) by agents (nigericin, carbonylcyanide-3-chlorophenylhydrazone (CCCP)) which transport protons from the extracellular space into the cytoplasm. Cell killing is enhanced when these agents are used in combination with compounds (amiloride, 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS)) which inhibit the membrane-based exchangers responsible for the regulation of intracellular pH (pHi). We describe experiments which assess the ability of these agents to kill tumour cells in spheroids and in vivo. Both nigericin and CCCP were observed to penetrate tissue based on their ability to kill tumour cells in spheroids. The mean extracellular pH (pHe) of the KHT fibrosarcoma and the EMT-6 sarcoma were observed to be 0.21 and 0.32 pH units more acidic than the mean pHe in muscle tissue. Intraperitoneal (i.p.) administration of the vasodilator hydralazine (10 mg kg-1) caused a reduction of the mean pHe of the KHT but not the EMT-6 tumour. Nigericin (2.5 mg kg-1, i.p.) plus amiloride (10 mg kg-1, i.p.) followed 30 min later by hydralazine (10 mg kg-1, i.p.) reduced the surviving fraction of cells in the KHT and EMT-6 tumours, but had minimal effects on growth delay. When KHT tumours were treated with 15 Gy X-rays followed immediately by nigericin plus amiloride and hydralazine a reduced surviving fraction as well as an increase in tumour growth delay was observed compared to radiation alone. The administration of nigericin (2.5 mg kg-1, i.p.) or the combination of nigericin (2.5 mg kg-1, i.p.) followed by hydralazine (10 mg kg-1, intravenous (i.v.)) resulted in reductions of tumour pHi of 0.27 and 0.29 pH units respectively as determined by 31P magnetic resonance spectroscopy (MRS). Our results show that the combination of nigericin and hydralazine (with or without amiloride) can kill cells in rodent solid tumours and that cell killing is associated with a reduction in the mean pHi of tumour cells.
在组织培养中（培养基pH小于7.0）的酸性环境下，一些能将质子从细胞外转运到细胞质中的试剂（尼日利亚菌素、羰基氰-3-氯苯腙（CCCP））可实现细胞杀伤。当这些试剂与抑制负责调节细胞内pH（pHi）的膜性交换体的化合物（氨氯吡脒、4,4'-二异硫氰酸芪-2,2'-二磺酸（DIDS））联合使用时，细胞杀伤作用会增强。我们描述了评估这些试剂在球体和体内杀伤肿瘤细胞能力的实验。基于尼日利亚菌素和CCCP在球体中杀伤肿瘤细胞的能力，观察到它们能够穿透组织。观察到KHT纤维肉瘤和EMT-6肉瘤的平均细胞外pH（pHe）比肌肉组织中的平均pHe分别酸性高0.21和0.32个pH单位。腹腔注射（i.p.）血管扩张剂肼屈嗪（10 mg kg-1）可使KHT的平均pHe降低，但对EMT-6肿瘤无此作用。尼日利亚菌素（2.5 mg kg-1，i.p.）加氨氯吡脒（10 mg kg-1，i.p.），30分钟后再注射肼屈嗪（10 mg kg-1，i.p.），可降低KHT和EMT-6肿瘤中细胞的存活分数，但对生长延迟影响极小。当KHT肿瘤接受15 Gy X射线照射后立即给予尼日利亚菌素加氨氯吡脒和肼屈嗪时，与单独放疗相比，观察到存活分数降低以及肿瘤生长延迟增加。腹腔注射尼日利亚菌素（2.5 mg kg-1）或先腹腔注射尼日利亚菌素（2.5 mg kg-1）再静脉注射（i.v.）肼屈嗪（10 mg kg-1），通过31P磁共振波谱（MRS）测定，分别导致肿瘤pHi降低0.27和0.29个pH单位。我们的结果表明，尼日利亚菌素和肼屈嗪（有无氨氯吡脒）联合使用可杀伤啮齿动物实体瘤中的细胞，且细胞杀伤与肿瘤细胞平均pHi降低有关。
