CHK1抑制剂在MYC高表达的三阴性乳腺癌中协同致死作用的机制研究

Triple negative breast cancer (TNBC) is the most aggressive subtype of breast cancer and has had no effective treatment for a long time. Previous study indicated that MYC was overexpressed in TNBC and associated with poor prognosis, and MYC overexpression could induce DNA replication stress. Persistent replication stress will lead to replication fork collapse, and eventually cell death. Hence, we hypothesized that targeting replication tress response would aggravate replication stress and then induce cell death. To confirm the hypothesis，we compared the sensitivities of a variety of inhibitors targeting the factors which response to replication stress in TNBC after MYC being overexpressed or down-regulated, and then choose out CHK1 inhibitor. We speculated that CHK1 inhibitor might enhance replication stress and induce cell death by persistently activating CDK1/2 kinase. This project will further study the particular effect of CHK1 inhibitor in MYC-overexpressed TNBC in vitro and vivo model; the fundamental mechanisms of synergy between CHK1 inhibitor and MYC overexpression in TNBC and the role of CDK1/2 kinase in the synergy with DNA fiber assay and comet assay. These above studies may reveal a new perspective in targeting MYC to treat cancer and help to develop new treatment therapy for TNBC.

三阴性乳腺癌（TNBC）是恶性程度最高的乳腺癌亚型，尚无有效的治疗药物。前期研究提示：MYC在TNBC中高表达，其表达水平与不良预后密切相关，且MYC高表达会诱导DNA复制压力。持续的复制压力会导致复制叉崩解，引起细胞死亡。因此我们提出假说：在MYC高表达TNBC中，靶向复制压力调控分子，以加剧复制压力致死细胞。为验证这一假说，本课题前期已通过干扰或过表达TNBC细胞MYC表达后，比较多种复制压力调控抑制剂的敏感性，筛选出CHK1抑制剂。并猜想CHK1抑制剂可能通过持续激活CDK1/2加剧复制压力，引起DNA损伤和细胞死亡。本课题下一步将在体内外模型中明确CHK1抑制剂与MYC高表达协调抗TNBC的作用，并运用DNA纤维实验、彗星实验和流式技术等阐述具体的作用机制及CDK1/2在其中的作用。本研究旨在为靶向MYC的治疗提供新思路，也为TNBC治疗提供新策略。

三阴性乳腺癌（TNBC）是恶性程度最高和预后最差的乳腺癌亚型。前期研究提示：MYC在TNBC中高表达，其表达水平与不良预后密切相关，且MYC高表达会诱导DNA复制压力和DNA损伤。持续的复制压力和累积的DNA损伤会导致DNA复制的崩解，引起细胞死亡。我们猜想在MYC高表达TNBC中，进一步诱导DNA损失和复制压力能够引起细胞死亡。本课题通过干扰或过表达TNBC细胞MYC表达后，比较多种DNA损失反应（DDR）抑制剂的敏感性，发现MYC高表达TNBC细胞对CHK1抑制剂的敏感性要强于其他抑制剂，且MYC表达下调能降低CHK1抑制剂在TNBC中的敏感性。体外实验证实CHK1抑制剂能够显著抑制MYC高表达TNBC细胞的增殖克隆和迁徙侵袭，并诱导S期阻滞。体内模型也明确CHK1抑制剂与MYC高表达协调抗TNBC的作用。我们的研究证实CHK1抑制剂在MYC高表达TNBC中能够进一步诱导复制压力和加剧DNA损伤，从而诱导细胞死亡，达到协同致死。本研究为靶向MYC的治疗提供新思路，也为TNBC治疗提供新策略。目前已发表SCI论文3篇，一篇SCI论文修回中，协助培养博士研究生3名。