Genomic signatures as predictive biomarkers of homologous recombination deficiency in ovarian cancer

DNA repair deficiency is a common hallmark of many cancers and is increasingly recognised as a target for cancer therapeutics. Selecting patients for these treatments requires a functional assessment of multiple redundant DNA repair pathways. With the advent of whole-genome sequencing of cancer genomes, it is increasingly recognised that multiple signatures of mutational and chromosomal alterations can be correlated with specific DNA repair defects. The clinical relevance of this approach is underlined by the use of poly-(ADP-ribose) polymerase inhibitors (PARPi) in homologous recombination (HR) deficient high-grade serous ovarian cancers. Beyond deleterious mutations in HR-related genes such as BRCA1/2, it is recognised that HR deficiency endows ovarian cancers with specific signatures of base substitutions and structural chromosomal variation. Multiple metrics quantifying loss-of-heterozygosity (LOH) events were proposed and implemented in trials with PARPi. However, it was shown that some of the HR-deficient cases, i.e. CDK12–mutated tumours, were not associated with high LOH-based scores, but with distinct patterns of genomic alterations such as tandem duplication. Therefore, more complex signatures of structural genomic variation were identified and quantified. Ultimately, optimal prediction models for treatments targeting DNA repair will need to integrate multiples of these genomic signatures and will also need to assess multiple resistance mechanisms such as genomic reversion events that partially or fully re-activate DNA repair.     

The role of AFAP1-AS1 in mitotic catastrophe and metastasis of triple-negative breast cancer cells by activating the PLK1 signaling pathway

Triple-negative breast cancer (TNBC) is characterized by fast growth, high metastasis, high invasion, and a lack of therapeutic targets. Mitosis and metastasis of TNBC cells are two important biological behaviors in TNBC malignant progression. It is well known that the long noncoding RNA AFAP1-AS1 plays a crucial role in various tumors, but whether AFAP1-AS1 is involved in the mitosis of TNBC cells remains unknown. In this study, we investigated the functional mechanism of AFAP1-AS1 in targeting Polo-like Kinase 1 (PLK1) activation and participating in mitosis of TNBC cells. We detected the expression of AFAP1-AS1 in the TNBC patient cohort and primary cells by in situ hybridization (ISH), northern blot, fluorescent in situ hybridization (FISH) and cell nucleus/cytoplasm RNA fraction isolation. High AFAP1-AS1 expression was negatively correlated with overall survival (OS), disease-free survival (DFS), metastasis-free survival (MFS) and recurrence-free survival (RFS) in TNBC patients. We explored the function of AFAP1-AS1 by transwell, apoptosis, immunofluorescence (IF) and patient-derived xenograft (PDX) models in vitro and in vivo. We found that AFAP1-AS1 promoted TNBC primary cell survival by inhibiting mitotic catastrophe and increased TNBC primary cell growth, migration and invasion. Mechanistically, AFAP1-AS1 activated phosphorylation of the mitosis-associated kinase PLK1 protein. Elevated levels of AFAP1-AS1 in TNBC primary cells increased PLK1 pathway downstream gene expression, such as CDC25C, CDK1, BUB1 and TTK. More importantly, AFAP1-AS1 increased lung metastases in a mouse metastasis model. Taken together, AFAP1-AS1 functions as an oncogene that activates the PLK1 signaling pathway. AFAP1-AS1 could be used as a potential prognostic marker and therapeutic target for TNBC.     

同源重组缺陷检测在肿瘤临床诊疗中的研究进展与展望

同源重组(homologous recombination,HR)是修复DNA双链断裂、单链DNA间隙和停滞或折叠复制叉的主要途径,有助于端粒维持,确保减数分裂过程中染色体的正确分离.同源重组修复(homologous recombination repair,HRR)通路是DNA损伤修复通路之一,在肿瘤中有较高的突变...     

基于基因瘢痕评分(GSS)探索乳腺癌中的同源重组修复缺陷(HRD)

目的:使用基因瘢痕评分(GSS)描述中国乳腺癌人群的HRD状态,并对乳腺癌的HRD状态和临床特征进行统计学分析。方法:使用AmoyDx HRD Panel检测我院诊断的79例乳腺癌患者。根据拷贝数长度(LCN)、拷贝数部位(SCN)和拷贝数类型(TCN)确定基因组疤痕得分(GSS)。HRD阳性是指BRCA突变阳性和/或GSS得分≥50。HRD得分与临床特征之间的关系通过卡方检验和Fisher's精确检验及Wilcoxon秩和检验进行统计分析。结果:在79例患者中,BRCA突变阳性率10.1%,HRD阳性率35.4%。在TNBC患者中,HRD阳性率为80%,BRCA突变阳性率26.7%。53.4%的TNBC患者BRCA突变阴性但HRD阳性。与HRD阴性的乳腺癌相比,HRD阳性乳腺癌明显更可能是Ki-67高(P<0.05)、ER阴性(P<0.05)和PR阴性(P<0.05)的肿瘤。HRD阳性率在TNBC(80%)中也明显高于Luminal A(7.7%,P<0.001)和Luminal B(27.7%,P<0.05)。结论:GSS是乳腺癌同源重组缺陷的重要检测工具,能帮助挖掘BRCA突变阴性但HRD阳性的乳腺癌人群。HRD状态与乳腺癌的ER、PR和Ki-67状态相关。     

BRCA1/2突变和同源重组修复缺陷(HRD)检测在乳腺癌中的临床研究进展

乳腺癌已成为发病率最高的癌症。DNA修复缺陷是乳腺癌最重要的特征之一。先前的研究表明,乳腺癌易感基因1/2(breast cancer susceptibility gene 1/2,BRCA1/2)突变是预测乳腺癌同源重组修复缺陷(homologous recombination deficiency, HRD)最主要的生物标志物,能识别铂类药物和多腺苷二磷酸核糖聚合酶(poly ADP ribose polymerase, PARP)抑制剂治疗的获益人群。美国食品药品监督管理局(FDA)已批准Olaparib和Talazoparib两种PARP抑制剂,用于BRCA1/2突变的早期和晚期乳腺癌的辅助治疗。但中国尚未获批。现有研究表明,一部分非BRCA1/2突变的乳腺癌患者也具有HRD特征,可以从铂类药物或PARP抑制剂中获益。本综述总结了涉及到BRCA1/2突变、同源重组修复(homologous recombination repair, HRR)基因突变和HRD状态检测的临床研究。阐明了各种检测方法在识别乳腺癌患者HRD状态和预测疗效方面的价值,并提出应尽快开发用于中国乳腺癌HR...     

云南地区卵巢癌患者的基因同源重组缺陷状态和BRCA1/2基因突变频率及其临床意义

目的：采用基于中国人群单核苷酸多态性位点开发的同源重组缺陷（HRD）检测工具评估云南地区卵巢癌患者的HRD状态和BRCA1/2基因突变频率并探讨其临床意义。方法：共纳入2021 年1月至2023 年5月间在云南省肿瘤医院收治的卵巢癌患者248 例,HRD状态采用基因组瘢痕评分法（GSS）（主要依据拷贝数的长度、类型、位置及基因组断片）或HRD评分法（杂合性缺失、端粒等位基因失衡及大片段移位等基因组不稳定事件的总和）进行评估,当组织样本的GSS≥50 分或HRD评分≥42 分者或检测到有害的BRCA1/2基因突变时HRD被定义为阳性。分析患者HRD状态与临床病理特征的关系。结果：248 名卵巢癌患者中70.97%的患者HRD呈阳性,其中BRCA1/2基因突变率为30.65%。Ⅲ~Ⅵ期、高级别浆液腺癌的卵巢癌患者具有更高的HRD阳性率（均P<0.01）,HRD评分更高的患者其合并其他基因突变的频率也越高（P<0.05）。HRD状态与卵巢癌的病理类型、临床分期和其他基因突变均有关联（均P<0.01）。结论：云南地区卵巢癌患者HRD阳性率较高,HRD阳性的卵巢癌患者可以从聚ADP核糖聚合酶（PARP）抑制剂治疗中获得更大的收益。     

A novel small-molecule IAP antagonist,AZD5582, draws Mcl-1 down-regulation for induction of apoptosis through targeting of cIAP1 and XIAP in human pancreatic cancer

Inhibitor of apoptosis proteins (IAPs) plays an important role in controlling cancer cell survival. IAPs have therefore attracted considerable attention as potential targets in anticancer therapy. In this study, we investigated the anti-tumor effect of AZD5582, a novel small-molecule IAP inhibitor, in human pancreatic cancer cells. Treating human pancreatic cancer cells with AZD5582 differentially induced apoptosis, dependent on the expression of p-Akt and p-XIAP. Moreover, the knockdown of endogenous Akt or XIAP via RNA interference in pancreatic cancer cells, which are resistant to AZD5582, resulted in increased sensitivity to AZD5582, whereas ectopically expressing Akt or XIAP led to resistance to AZD5582. Additionally, AZD5582 targeted cIAP1 to induce TNF-α-induced apoptosis. More importantly, AZD5582 induced a decrease of Mcl-1 protein, a member of the Bcl-2 family, but not that of Bcl-2 and Bcl-xL. Interestingly, ectopically expressing XIAP and cIAP1 inhibited the AZD5582-induced decrease of Mcl-1 protein, which suggests that AZD5582 elicits Mcl-1 decrease for apoptosis induction by targeting of XIAP and cIAP1. Taken together, these results indicate that sensitivity to AZD5582 is determined by p-Akt-inducible XIAP phosphorylation and by targeting cIAP1. Furthermore, Mcl-1 in pancreatic cancer may act as a potent marker to analyze the therapeutic effects of AZD5582.