Inhibition of checkpoint kinase 1 abrogates G2/M checkpoint activation and promotes apoptosis under heat stress

Abstract

Hyperthermia induced by heat stress (HS) inhibits the proliferation of cancer cells and induces their apoptosis. However, the mechanism underlying HS-induced apoptosis remains elusive. Here, we demonstrated a novel evidence that checkpoint kinase 1 (Chk1) plays crucial roles in the apoptosis and regulation of cell cycle progression in cells under HS. In human leukemia Jurkat cells, interestingly, the ataxia telangiectasia and Rad-3 related (ATR)-Chk1 pathway was preferentially activated rather than the ataxia telangiectasia mutated (ATM)-checkpoint kinase 2 (Chk2) pathway under HS. The selective inhibitors of ATR or Chk1 abrogated HS-induced apoptosis in human leukemia Jurkat cells whereas the inhibition of ATM or Chk2 caused only marginal effects. Inhibition of ATR and Chk1 also abrogated G2/M checkpoint activation by HS in Jurkat cells. The effects of small interfering RNA targeting Chk1 were similar to those of the selective inhibitor of Chk1. In addition, the efficiencies of Chk1 inhibition on G2/M checkpoint abrogation and apoptosis induction were confirmed in the adherent cancer cell lines HeLa, HSC3, and PC3, suggesting that the targeting of Chk1 can be effective in solid tumors cells. In conclusion, these findings indicate a novel molecular basis of G2/M checkpoint activation and apoptosis in cells exposed to HS.

Heat induction of a novel Rad9 variant from a cryptic translation initiation site reduces mitotic commitment

“…Activation of Rad3 ensures that Chk1 kinase remains in a hypo-phosphorylated state thereby preventing premature mitosis under heat stress conditions. These findings are consistent with a recent report showing that ATR Rad3 -to-Chk1 signalling is activated when human cells are exposed to elevated temperatures (Furusawa et al, 2011). Which heat alterations stimulate ATR is unknown and its signalling output is the phosphorylation of Chk1 at S345 and not its dephosphorylation.…”

“…An increase in reactive oxygen activates ATM directly in the absence of the MRN complex by inducing the formation of a disulfide-crosslinked dimer (Guo et al, 2010). The cellular targets of ATM at high temperatures remain to be identified, but they may be linked with apoptosis (Furusawa et al, 2011) or a prolonged G2-M arrest (Zölzer and Streffer, 2001). …”

The Error-Prone DNA Polymerase κ Promotes Temozolomide Resistance in Glioblastoma through Rad17-Dependent Activation of ATR-Chk1 Signaling

“…6A). ATR-Chk1 pathway is a critical regulator of the cellular response to DNA damage and replication stress, and interruption of this signaling may result in the impairment of the S-phase checkpoint function and also abrogate G 2 -M checkpoint activation (26). Thus, we wondered whether Pol k could impact S or G 2 checkpoint responses to temozolomideinduced DNA damage.…”

Effects of hyperthermia as a mitigation strategy in DNA damage-based cancer therapies

“…Alternatively, hyperthermia can create chromosomal lesions which if not removed during mitosis can result in triggering cell death pathways [38].…”

“…Following ATM activation, 53BP1 interacts with its effector molecule, RIF1, which is recruited at the sites of DSBs and is also antagonized by BRCA1 and CtIP leading to the induction of the appropriate DNA repair pathway(s) [47]. Moreover, hyperthermia has been shown to delay the employment of 53BP1 in MRN complex formation [23] whereas activation of ATM is decelerated after heat exposure [38]. Furthermore, data from other reports have associated the activation of ATM with generation of oxidative stress as it was shown that ROS can oxidize the disulfide bond between the monomers of the ATM dimer without the presence of MRN and thus causing directly its activation [48].…”