Knock-down of hypoxia-induced carbonic anhydrases IX and XII radiosensitizes tumor cells by increasing intracellular acidosis.
Knock-down of hypoxia-induced carbonic anhydrases IX and XII radiosensitizes tumor cells by increasing intracellular acidosis.
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DOI：
10.3389/fonc.2012.00199
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发表时间：
2012
影响因子：
4.7
通讯作者：
Chiche J
中科院分区：
文献类型：
--
作者：
Doyen J;Parks SK;Marcié S;Pouysségur J;Chiche J
肿瘤微环境内的酸中毒与缺氧肿瘤细胞的放射抗性之间的关系仍不清楚。此前，我们报道了缺氧诱导的碳酸酐酶（CA）IX和CAXII构成了强大的细胞内pH（pHi）调节系统，赋予缺氧人结肠癌LS174Tr细胞在酸性微环境中的生存优势。在这里，我们研究了酸中毒、CAIX 和 CAXII 敲低与电离辐射相结合的作用。分析成纤维细胞 (-/+ CAIX) 和 LS174Tr 细胞（ca9/ca12 的诱导敲低）在细胞外 pHo 操作和缺氧 (1% O2) 暴露中照射后的细胞周期时相分布和存活率。放射疗法用于靶向裸鼠体内生长的 ca9/ca12 沉默的 LS174Tr 肿瘤。我们发现，通过抑制 Na+/H+ 交换器 1 来降低成纤维细胞的 pHi 调节能力，可使细胞对辐射诱导的细胞死亡敏感。其次，CAIX 的 pHi 调节功能对酸性环境中受辐射的成纤维细胞起着关键的保护作用，同时伴随着细胞周期放射敏感期细胞数量的减少。第三，我们证明，对 ca9 或 ca9/ca12 均沉默的 LS174Tr 球体进行照射，由于抗辐射 S 期细胞数量减少和 CA 介导的 pHi 调节破坏，细胞死亡分别增加 50% 和 75%。最后，当 ca9/ca12 沉默与体内照射相结合时，LS174Tr 肿瘤进展明显减少。这些发现强调了放疗与靶向 pHi 调节 CA 的组合使用作为一种抗癌策略。
The relationship between acidosis within the tumor microenvironment and radioresistance of hypoxic tumor cells remains unclear. Previously we reported that hypoxia-induced carbonic anhydrases (CA) IX and CAXII constitute a robust intracellular pH (pHi)-regulating system that confers a survival advantage on hypoxic human colon carcinoma LS174Tr cells in acidic microenvironments. Here we investigate the role of acidosis, CAIX and CAXII knock-down in combination with ionizing radiation. Fibroblasts cells (-/+ CAIX) and LS174Tr cells (inducible knock-down for ca9/ca12) were analyzed for cell cycle phase distribution and survival after irradiation in extracellular pHo manipulations and hypoxia (1% O2) exposure. Radiotherapy was used to target ca9/ca12-silenced LS174Tr tumors grown in nude mice. We found that diminishing the pHi-regulating capacity of fibroblasts through inhibition of Na+/H+ exchanger 1 sensitize cells to radiation-induced cell death. Secondly, the pHi-regulating function of CAIX plays a key protective role in irradiated fibroblasts in an acidic environment as accompanied by a reduced number of cells in the radiosensitive phases of the cell cycle. Thirdly, we demonstrate that irradiation of LS174Tr spheroids, silenced for either ca9 or both ca9/ca12, showed a respective 50 and 75% increase in cell death as a result of a decrease in cell number in the radioresistant S phase and a disruption of CA-mediated pHi regulation. Finally, LS174Tr tumor progression was strongly decreased when ca9/ca12 silencing was combined with irradiation in vivo. These findings highlight the combinatory use of radiotherapy with targeting of the pHi-regulating CAs as an anti-cancer strategy.