Sørensen Belinda Halling, Dam Celina Støving, Stürup Stefan, Lambert Ian Henry
University of Copenhagen, Department of Biology, Universitetsparken 13, 2100 Copenhagen Ø, Denmark.
University of Copenhagen, Department of Biology, Universitetsparken 13, 2100 Copenhagen Ø, Denmark; University of Copenhagen, Department of Pharmacy, Universitetsparken 2, 2100 Copenhagen Ø, Denmark.
J Inorg Biochem. 2016 Jul;160:287-95. doi: 10.1016/j.jinorgbio.2016.04.004. Epub 2016 Apr 13.
Acquired resistance to chemotherapeutic drugs in cancer cells can reflect an ability to limit cellular drug availability, to repair drug induced DNA damage, and to limit initiation/progression of cell death (apoptosis). The leucine-rich-repeat-containing 8A (LRRC8A) protein is an essential component of volume sensitive channels for organic osmolytes (VSOAC) and volume regulated anion channels (VRAC), which are activated during the apoptotic process. Here we illustrate that cisplatin resistance in human ovarian cancer cells (A2780) correlates with a reduced expression of LRRC8A and copper transporter receptor 1 (CTR1), as well as a concomitant increased expression of copper-transporting P-type ATPases (ATP7A/ATP7B). We also find that cisplatin (Pt) accumulation correlates with LRRC8A protein expression and channel activity, i.e., the cellular Pt content is high when VSOAC is activated by depolarization of the plasma membrane or hypoosmotic cell swelling, and reduced when channel activity/LRRC8A expression is reduced by genetically silencing/pharmacological inhibition, or the cells have acquired a resistant phenotype with low LRRC8A protein expression. It is suggested that reduced LRRC8A expression in cisplatin-resistant A2780 cells ensures cell survival through limitation in cisplatin accumulation and a concomitant reduction in osmolytes loss via VSOAC/VRAC and hence instigation of the apoptotic process.
癌细胞对化疗药物产生的获得性耐药可能反映出其限制细胞内药物可利用性、修复药物诱导的DNA损伤以及限制细胞死亡（凋亡）起始/进程的能力。富含亮氨酸重复序列8A（LRRC8A）蛋白是有机渗透溶质容积敏感通道（VSOAC）和容积调节性阴离子通道（VRAC）的重要组成部分，这些通道在凋亡过程中被激活。在此我们表明，人卵巢癌细胞（A2780）中的顺铂耐药与LRRC8A和铜转运受体1（CTR1）表达降低相关，同时铜转运P型ATP酶（ATP7A/ATP7B）表达增加。我们还发现顺铂（Pt）蓄积与LRRC8A蛋白表达及通道活性相关，即当质膜去极化或低渗性细胞肿胀激活VSOAC时，细胞内Pt含量较高；而当通过基因沉默/药物抑制使通道活性/LRRC8A表达降低，或细胞获得低LRRC8A蛋白表达的耐药表型时，细胞内Pt含量降低。这表明顺铂耐药的A2780细胞中LRRC8A表达降低，通过限制顺铂蓄积以及随之减少经由VSOAC/VRAC的渗透溶质丢失，从而确保细胞存活，进而阻止凋亡进程。
