Department of Liberal Arts and Sciences, Toyama Prefectural University, Kurokawa 5180, Toyama, 939-0398, Japan.
Department of Radiological Sciences, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, Japan.
Apoptosis. 2017 Oct;22(10):1225-1234. doi: 10.1007/s10495-017-1402-2.
Hyperthermia induced by heat stress (HS) is known to inhibit proliferation and induce cell death in cancer. We previously demonstrated that checkpoint kinase 1 (Chk1) contributes to G/M arrest and cell survival under HS; however, the role of Chk2, a functional analog of Chk1, in regulation of the cell cycle and cell death under HS is still unknown. Here, we addressed the role of Chk2 using Molt-4 cells with p53-targeted shRNA (Molt-4/shp53) and parental control cells (Molt-4/V). Chk2 inhibition suppressed C-terminal acetylation of p53 and delayed the induction of p53-target genes in Molt-4/V cells under HS; however, Chk2 inhibition failed to inhibit apoptosis induced by HS, indicating that Chk2 was dispensable for p53-dependent apoptosis under HS. In contrast, Chk2 inhibition abrogated G/M arrest and promoted cell death induced by HS in HeLa cells and Molt-4/shp53 cells. Thus, we demonstrated for the first time that Chk2 was required for cell cycle arrest and cell survival, particularly in cells with p53 defects under HS. These findings indicated that Chk2 may be a selective target for p53-mutated or -deficient cancer treated with hyperthermia.
热应激引起的高温能抑制癌细胞增殖并诱导其死亡。我们之前的研究表明，检查点激酶 1（Chk1）在热应激下有助于 G2/M 期阻滞和细胞存活；然而，Chk2（Chk1 的功能类似物）在热应激下调控细胞周期和细胞死亡的作用仍不清楚。在这里，我们利用靶向 p53 的短发夹 RNA（shRNA）的 Molt-4 细胞（Molt-4/shp53）和亲本对照细胞（Molt-4/V）研究了 Chk2 的作用。Chk2 抑制作用抑制了热应激下 Molt-4/V 细胞中 p53 的 C 端乙酰化和 p53 靶基因的诱导；然而，Chk2 抑制并不能抑制热应激诱导的细胞凋亡，表明 Chk2 对于热应激下 p53 依赖性凋亡是可有可无的。相比之下，Chk2 抑制作用消除了 HeLa 细胞和 Molt-4/shp53 细胞中热应激诱导的 G2/M 期阻滞和促进细胞死亡。因此，我们首次证明 Chk2 对于热应激下细胞周期阻滞和细胞存活是必需的，特别是在 p53 缺陷的细胞中。这些发现表明，Chk2 可能是 p53 突变或缺失的癌症在接受高温治疗时的一个选择性靶点。
