Elucidating the relevance of BARD1-PLK1 interaction in PDAC and response to therapy

摘要 胰腺导管腺癌（PDAC）是一种侵袭性癌症，治疗选择有限。整体 5-年存活率仅为11%，对更好的治疗方法的需求未得到满足。对于同源性 重组修复（HRR）缺陷型肿瘤（BRCA 1/2、PALB 2）、聚（ADP-核糖）聚合酶（PARP）抑制剂 （PARPi）/铂类药物治疗提供了最佳的个性化治疗方法。然而， 由于固有的（HRR有效肿瘤）或获得性耐药性，这些治疗常常受到限制。这 强调迫切需要确定新的目标，以提高这些有前途的代理的敏感性，并扩大 PDAC患者人群可以从中受益。我们最近发现BARD 1（BRCA 1- 相关的-环-结构域-1），BRCA 1的一种专性结合伴侣，也是HR的一个关键因子， DNA损伤条件下的PDAC细胞（Jain等Cancers（巴塞尔）6;14（7）：1848，2022）。我们发现 BARD 1的缺失使得PDAC细胞（HRR熟练）对PARPi/铂极其敏感，并且增强了PDAC细胞对PARPi/铂的敏感性。 DNA损伤。尽管这些效应可能归因于BARD 1在HRR、转录组和转录调控中的典型作用， BARD 1沉默细胞的特征分析表明BARD 1对与细胞周期相关的细胞功能具有多效性作用， 细胞衰老和DNA复制。与这些预测一致，我们注意到BARD 1沉默强烈地抑制了BARD 1的表达。 PDAC细胞的细胞增殖减少，体外克隆形成能力降低，体内肿瘤生长减慢， 减少几种细胞周期蛋白的表达，特别是Polo样激酶-1（PLK-1）。PLK-1是丝氨酸 通过有丝分裂强烈促进细胞进展的苏氨酸激酶。PLK-1过表达于 PDAC和PLK-1活性的失调有助于遗传不稳定性，这反过来又导致致癌性肿瘤。 转型我们推测PLK-1与BARD 1相互作用，这种相互作用是PDAC细胞增殖所必需的。 对DNA损伤剂的反应。我们将通过两个具体目标来检验我们的假设。在目标1中， 使用生物化学测定法确定PDAC细胞中BARD 1和PLK-1的分子相互作用， 2，我们将确定BARD 1对PDAC细胞中PLK-1的调节是否是对DNA损伤剂反应的驱动因素， 在小鼠模型中使用过表达系统。该项目的总体目标是阐明 BARD 1-PLK-1相互作用在PDAC和对DNA损伤剂治疗反应中的意义。的 该项目的完成将为开发新的靶向治疗策略奠定基础， PDAC，在未来也可以应用于其他癌症类型。 关键词：胰腺导管腺癌，DNA损伤，细胞周期，BARD 1

ABSTRACT Pancreatic ductal adenocarcinoma (PDAC) is an aggressive cancer with limited treatment options. The overall 5-year survival rate is only 11% and there is an unmet need for better therapies. For patients with homologous recombination repair (HRR) deficient tumors (BRCA1/2, PALB2), poly (ADP-ribose) polymerase (PARP) inhibitor (PARPi)/platinum-based therapies offer the best-personalized treatment approach. However, the efficacy of these treatments is often limited due to inherent (HRR proficient tumors) or acquired drug resistance. This underscores a dire need to identify new targets to enhance the sensitivity of these promising agents and expand the PDAC patient population that could benefit from them. We recently discovered that BARD1 (BRCA1- Associated- Ring- Domain- 1), an obligate binding partner of BRCA1 and a key factor in HR, is upregulated in PDAC cells under DNA damage conditions (Jain et al Cancers (Basel) 6;14(7):1848, 2022). We found that deletion of BARD1 rendered PDAC cells (HRR proficient) extremely sensitive to PARPi/platinums and enhanced DNA damage. Although, these effects may be attributed to BARD1’s canonical role in HRR, transcriptome profiling of BARD1 silenced cells suggests BARD1 has pleiotropic effects on cellular functions linked to cell cycle, cellular senescence, and DNA replication. In line with these predictions, we noted that BARD1 silencing strongly reduced cell proliferation, decreased clonogenic capacity in vitro, slowed tumor growth in vivo of PDAC cells and reduced expression of several cell cycle proteins, notably Polo-Like-Kinase-1 (PLK-1). PLK-1 is a serine threonine kinase that strongly promotes the progression of cells through mitosis. PLK-1 is overexpressed in PDAC and deregulation of PLK-1 activity contributes to genetic instability, which in turn leads to oncogenic transformation. We hypothesize that PLK-1 interacts with BARD1 and this interaction is necessary for PDAC cell response to DNA damage agents. We will test our hypothesis through two specific aims. In aim 1, we will determine the molecular interaction of BARD1 and PLK-1 in PDAC cells using biochemical assays, and in aim 2, we will determine if BARD1’s regulation of PLK-1 in PDAC cells is a driver of response to DNA damage agents, using overexpression systems in a murine model. The overarching goal of this project is to elucidate the role and significance of BARD1-PLK-1 interaction in PDAC and therapy response to DNA damage agents. The completion of this project will lay the groundwork for development of novel targeted therapeutic strategies against PDAC, and in the future could be applied to other cancer types as well. Keywords: Pancreatic ductal adenocarcinoma, DNA damage, cell cycle, BARD1