Vernalis (R&D) Ltd, Granta Park, Abington, Cambridge, CB21 6GB, UK.
Vernalis (R&D) Ltd, Granta Park, Abington, Cambridge, CB21 6GB, UK.
DNA Repair (Amst). 2021 May;101:103099. doi: 10.1016/j.dnarep.2021.103099. Epub 2021 Mar 13.
Inhibitors of Chk1 kinase, a key effector of the DNA damage response pathway, are currently undergoing Phase 1 and 2 clinical trials as single agents and in combination with cytotoxic chemotherapy. Understanding the biological effects of Chk1 inhibitors on cancer cells is critical for their continued clinical development. Treatment of adherent HT29 or HCC1937 cancer cells or suspension Jurkat or THP1 cells with a Chk1 inhibitor increased γH2AX in these cells. Chk1i pre-treated HCC1937 or HT29 cells resulted in γH2AX induction in cocultured Jurkat or THP1 cells despite these cells never being treated with a Chk1i. Pre-treatment of HT29 cells with camptothecin or gemcitabine followed by a Chk1i increased the DNA damage bystander effect in naïve cocultured THP1 cells compared to camptothecin or gemcitabine alone. This bystander effect appeared to occur through soluble factors via ATR, ATM, and DNA-PKcs activation in the bystander cells. Chk1 silencing by siRNA in HCC1937 or HT29 cells induced a DNA damage bystander effect in cocultured THP1 cells. However, this bystander effect induced by siRNA appeared mechanistically different to that induced by the Chk1 inhibitor. This work suggests that a Chk1 inhibitor-induced bystander effect may increase the clinical effectiveness of Chk1 inhibitors by inducing additional DNA damage or replication stress in cancer cells not directly exposed to the inhibitor. Conversely, it may also contribute to Chk1 inhibitor toxicity by increasing DNA damage in non-tumour cells.
Chk1 激酶抑制剂是 DNA 损伤反应途径的关键效应因子，目前正在进行 I 期和 II 期临床试验，作为单一药物以及与细胞毒性化疗联合使用。了解 Chk1 抑制剂对癌细胞的生物学影响对于其持续的临床开发至关重要。用 Chk1 抑制剂处理贴壁的 HT29 或 HCC1937 癌细胞或悬浮的 Jurkat 或 THP1 细胞会增加这些细胞中的 γH2AX。即使 HCC1937 或 HT29 细胞从未用 Chk1i 处理，预先用 Chk1i 处理的 HCC1937 或 HT29 细胞也会导致共培养的 Jurkat 或 THP1 细胞中诱导 γH2AX。与单独使用喜树碱或吉西他滨相比，先用喜树碱或吉西他滨预处理 HT29 细胞，然后用 Chk1i 处理会增加未处理的共培养 THP1 细胞中的 DNA 损伤旁观者效应。这种旁观者效应似乎通过旁观者细胞中 ATR、ATM 和 DNA-PKcs 的激活通过可溶性因子发生。在 HCC1937 或 HT29 细胞中用 siRNA 沉默 Chk1 会在共培养的 THP1 细胞中诱导 DNA 损伤旁观者效应。然而，这种由 siRNA 诱导的旁观者效应在机制上与由 Chk1 抑制剂诱导的旁观者效应不同。这项工作表明，Chk1 抑制剂诱导的旁观者效应可能通过在未直接暴露于抑制剂的癌细胞中诱导额外的 DNA 损伤或复制应激来增加 Chk1 抑制剂的临床效果。相反，它也可能通过增加非肿瘤细胞中的 DNA 损伤而导致 Chk1 抑制剂毒性增加。
