pSer784-VCP: a clinically relevant link between autophagy and DNA damage response

项目摘要 自噬和DNA损伤反应（DDR）是两个在进化上保守的， 细胞程序两者都可以在癌症中解除管制，并反过来作为癌症治疗的目标。尽管 令人信服的证据表明，自噬和DDR是相连的，已知的DDR相关的数量很少， 自噬靶标极大地限制了我们对其功能性串扰的理解。关于联合国难民事务高级专员办事处 自噬激活的化疗增敏作用强烈表明， 自噬在DDR中的生理作用。我们假设这种上下文依赖性可以由以下因素决定： 受影响的自噬目标对DDR的功能重要性。在这份资助中，我们专注于一个重要的 DDR因素称为VCP。VCP是一种广泛表达的AAA+ ATP酶，它识别多聚泛素化的 通过泛素-蛋白酶体和自噬/溶酶体途径促进其降解。 我们最近的工作表明，DNA损伤诱导的Ser 784磷酸化选择性地增加核VCP 功能为DDR。重要的是，pSer 784-VCP是化疗治疗的乳腺癌的不良预后标志物 患者这些数据表明，靶向pSer 784-VCP可能是一种新的和有效的化疗增敏剂。 approach.在这项授权中，我们提出的初步数据表明，pSer 784-VCP可能是一个以前的 自噬的未知目标。在目标1中，我们将定义参与的特定自噬途径 pSer 784-VCP降解，并寻找pSer 784-VCP在 DNA损伤。在目标2中，我们将在一组三阴性乳腺癌细胞系中测试DNA是否 损伤诱导的pSer 784-VCP水平预测自噬调节剂的化学增敏作用。在一起， 这些实验将提高我们对自噬和DDR之间的功能串扰的理解， 并帮助定义这两种细胞程序的共同靶向的生物学背景， 治疗上有益。

PROJECT SUMMARY Autophagy and DNA damage response (DDR) are two evolutionarily conserved, fundamentally important cellular programs. Both can be deregulated in cancer and in turn targeted as cancer therapies. Despite compelling evidence that autophagy and DDR are connected, the scarce number of known DDR-relevant autophagy targets greatly limits our understanding of their functional crosstalk. Mixed reports regarding the chemotherapy-sensitizing effect of autophagy activation strongly suggest the context-dependency of the physiological role of autophagy in DDR. We hypothesize that this context-dependency could be determined by the functional importance of the affected autophagy targets for DDR. In this grant, we focus on an important DDR factor named VCP. VCP is a ubiquitously expressed AAA+ ATPase which recognizes polyubiquitinated proteins and facilitates their degradation by both the ubiquitin-proteasome and autophagy/lysosome pathways. Our recent work showed that DNA damage-induced Ser784 phosphorylation selectively increases nuclear VCP function for DDR. Importantly, pSer784-VCP is poor prognostic marker for chemotherapy-treated breast cancer patients. These data suggest that targeting pSer784-VCP may be a novel and effective chemo-sensitizing approach. In this grant, we present preliminary data showing that pSer784-VCP may be a previously unrecognized target of autophagy. In Aim 1, we will define the specific autophagy pathway that is involved in pSer784-VCP degradation and seek for direct evidence that pSer784-VCP undergoes nuclear export upon DNA damage. In Aim 2, we will test in a large panel of triple-negative breast cancer cell lines whether DNA damage-induced pSer784-VCP levels predict chemo-sensitizing effects of autophagy modulators. Together, these experiments will improve our understanding of the functional crosstalk between autophagy and DDR, and help define the biological context within which co-targeting of these two cellular programs can be therapeutically beneficial.