IK1 channel activity contributes to cisplatin sensitivity of human epidermoid cancer cells
IK1 channel activity contributes to cisplatin sensitivity of human epidermoid cancer cells
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DOI：
10.1152/ajpcell.00428.2007
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发表时间：
2008-06-01
影响因子：
5.5
通讯作者：
Okada, Yasunobu
中科院分区：
文献类型：
--
作者：
Lee, Elbert L.;Hasegawa, Yuichi;Okada, Yasunobu
顺铂是一种以铂为基础的药物，是对抗多种癌症的重要武器。它通过与DNA形成加合物诱导细胞凋亡，尽管其作用机制的许多方面仍有待阐明。先前，我们发现了容量敏感的，向外矫正的Cl-通道在顺铂诱导的细胞凋亡中的作用。为了研究阳离子通道在细胞对顺铂的反应中也有作用的可能性，我们用全细胞膜片钳法检测了顺铂敏感的KB-3 （KB）表皮样癌细胞中阳离子通道的活性。低压应激激活的KB细胞中的阳离子通道被确定为Ca2+激活的中电导K+ (IK1)通道，基于其对细胞内Ca2+的需求，其被阻滞剂克霉唑和三芳基甲烷-34阻断，以及其被显性负结构抑制。在KB细胞衍生的顺铂耐药细胞系KCP-4细胞中未观察到该通道的活性，并且通过半定量RT-PCR和免疫染色观察其分子表达明显降低。细胞体积测量证实了IK1通道作为KB细胞体积调节机制的一个组成部分的生理作用。研究了IK1通道在顺铂诱导的细胞凋亡中的可能作用。发现氯霉唑和三芳基甲烷-34抑制顺铂诱导的细胞活力下降和caspase-3/7活性增加，而通道激活剂1-乙基-2-苯并咪唑啉酮则具有相反的作用。因此，IK1通道活性至少在一定程度上介导了KB细胞对顺铂治疗的反应。
Cisplatin, a platinum-based drug, is an important weapon against many types of cancer. It induces apoptosis by forming adducts with DNA, although many aspects of its mechanism of action remain to be clarified. Previously, we found a role for the volume-sensitive, outwardly rectifying Cl- channel in cisplatin-induced apoptosis. To investigate the possibility that cation channels also have a role in the cellular response to cisplatin, we examined the activity of cation channels in cisplatin-sensitive KB-3-1 (KB) epidermoid cancer cells by the whole cell patch-clamp method. A cation channel in KB cells, activated by hypotonic stress, was identified as the Ca2+-activated, intermediate-conductance K+ (IK1) channel on the basis of its requirement for intracellular Ca2+, its blockage by the blockers clotrimazole and triarylmethane-34, and its suppression by a dominant-negative construct. Activity of this channel was not observed in KCP-4 cells, a cisplatin-resistant cell line derived from KB cells, and its molecular expression, observed by semiquantitative RT-PCR and immunostaining, appeared much reduced. Cell volume measurements confirmed a physiological role for the IK1 channel as a component of the volume-regulatory machinery in KB cells. A possible role of the IK1 channel in cisplatin-induced apoptosis was investigated. It was found that clotrimazole and triarylmethane-34 inhibited a cisplatin-induced decrease in cell viability and increase in caspase-3/7 activity, whereas 1-ethyl-2-benzimidazolinone, an activator of the channel, had the opposite effect. Thus IK1 channel activity appears to mediate, at least in part, the response of KB cells to cisplatin treatment.