Establishing the homologous recombination score threshold in metastatic prostate cancer patients to predict the efficacy of PARP inhibitors

Background:The homologous recombination deficiency(HRD)score serves as a promising biomarker to iden-tify patients who are eligible for treatment with PARP inhibitors(PARPi).Previous studies have suggested a 3-biomarker Genomic Instability Score(GIS)threshold of≥42 as a valid biomarker to predict response to PARPi in patients with ovarian cancer and breast cancer.However,the GIS threshold for prostate cancer(PCa)is still lacking.Here,we conducted an exploratory analysis to investigate an appropriate HRD score threshold and to evaluate its ability to predict response to PARPi in PCa patients.Methods:A total of 181 patients with metastatic castration-resistant PCa were included in this study.Tumor tissue specimens were collected for targeted next-generation sequencing for homologous recombination repair(HRR)genes and copy number variation(CNV)analysis.The HRD score was calculated based on over 50,000 single-nucleotide polymorphisms(SNP)distributed across the human genome,incorporating three SNP-based as-says:loss of heterozygosity,telomeric allelic imbalance,and large-scale state transition.The HRD score threshold was set at the last 5th percentile of the HRD scores in our cohort of known HRR-deficient tumors.The relation-ship between the HRD score and the efficacy in 16 patients of our cohort who received PARPi treatment were retrospectively analyzed.Results:Genomic testing was succeeded in 162 patients.In our cohort,61 patients(37.7%)had HRR mutations(HRRm).BRCA mutations occurred in 15 patients(9.3%).The median HRD score was 4(ranged from 0 to 57)in the total cohort,which is much lower than that in breast and ovarian cancers.Patients who harbored HRRm and BRCA or TP53 mutations had higher HRD scores.CNV occured more frequently in patients with HRRm.The last 5th percentile of HRD scores was 43 in the HRR-mutant cohort and consequently HRD high was defined as HRD scores≥43.In the 16 patients who received PARPi in our cohort,4 patients with a high HRD score achieved an objective response rate(ORR)of 100%while 12 patients with a low HRD score achieved an ORR of 8.3%.Progression-free survival(PFS)in HRD high patients was longer compared to HRD low patients,regardless of HRRm.Conclusions:A HRD score threshold of 43 was established and preliminarily validated to predict the efficacy of PARPi in this study.Future studies are needed to further verify this threshold.

Low testing rates and high BRCA prevalence: Poly (ADP-ribose) polymerase inhibitor use in Middle East BRCA/homologous recombination deficiency-positive cancer patients

BACKGROUND Poly(ADP-ribose)polymerase inhibitors(PARPis)are approved as first-line therapies for breast cancer gene(BRCA)-positive,human epidermal growth factor receptor 2-negative locally advanced or metastatic breast cancer.They are also effective for new and recurrent ovarian cancers that are BRCA-or homologous recombination deficiency(HRD)-positive.However,data on these mutations and PARPi use in the Middle East are limited.AIM To assess BRCA/HRD prevalence and PARPi use in patients in the Middle East with breast/ovarian cancer.METHODS This was a single-center retrospective study of 57 of 472 breast cancer patients tested for BRCA mutations,and 25 of 65 ovarian cancer patients tested for HRD.These adult patients participated in at least four visits to the oncology service at our center between August 2021 and May 2023.Data were summarized using descriptive statistics and compared using counts and percentages.Response to treatment was assessed using Response Evaluation Criteria in Solid Tumors criteria.RESULTS Among the 472 breast cancer patients,12.1%underwent BRCA testing,and 38.5%of 65 ovarian cancer patients received HRD testing.Pathogenic mutations were found in 25.6%of the tested patients:26.3%breast cancers had germline BRCA(gBRCA)mutations and 24.0%ovarian cancers showed HRD.Notably,40.0%of gBRCA-positive breast cancers and 66.0%of HRD-positive ovarian cancers were Middle Eastern and Asian patients,respectively.PARPi treatment was used in 5(33.3%)gBRCA-positive breast cancer patients as first-line therapy(n=1;7-months progression-free),for maintenance(n=2;>15-months progression-free),or at later stages due to compliance issues(n=2).Four patients(66.6%)with HRD-positive ovarian cancer received PARPi and all remained progression-free.CONCLUSION Lower testing rates but higher BRCA mutations in breast cancer were found.Ethnicity reflected United Arab Emirates demographics,with breast cancer in Middle Eastern and ovarian cancer in Asian patients.

Homologous recombination in DNA repair and DNA damage tolerance

Homologous recombination （HR） comprises a series of interrelated pathways that function in the repair of DNA double-stranded breaks （DSBs） and interstrand crosslinks （ICLs）. In addition, recombination provides critical support for DNA replication in the recovery of stalled or broken replication forks, contributing to tolerance of DNA damage. A central core of proteins, most critically the RecA homolog Rad51, catalyzes the key reactions that typify HR： homology search and DNA strand invasion. The diverse functions of recombination are reflected in the need for context-specific factors that perform supplemental functions in conjunction with the core proteins. The inability to properly repair complex DNA damage and resolve DNA replication stress leads to genomic instability and contributes to cancer etiology. Mutations in the BRCA2 recombination gene cause predisposition to breast and ovarian cancer as well as Fanconi anemia, a cancer predisposition syndrome characterized by a defect in the repair of DNA interstrand crosslinks. The cellular functions of recombination are also germane to DNA-based treatment modalities of cancer, which target replicating cells by the direct or indirect induction of DNA lesions that are substrates for recombination pathways. This review focuses on mechanistic aspects of HR relating to DSB and ICL repair as well as replication fork support.

BLM helicase inhibition synergizes with PARP inhibition to improve the radiosensitivity of olaparib resistant non-small cell lung cancer cells by inhibiting homologous recombination repair

Objective:We aimed to investigate the radiosensitizing efficacy of the poly-ADP-ribose polymerase(PARP)inhibitor,olaparib,and the Bloom syndrome protein(BLM)helicase inhibitor,ML216,in non-small cell lung cancer(NSCLC)cells.Methods:Radiosensitization of NSCLC cells was assessed by colony formation and tumor growth assays.Mechanistically,the effects of ML216,olaparib,and radiation on cell and tumor proliferation,DNA damage,cell cycle,apoptosis,homologous recombination(HR)repair,and non-homologous end joining(NHEJ)repair activity were determined.Results:Both olaparib and ML216 enhanced the radiosensitivities of olaparib-sensitive H460 and H1299 cells,which was seen as decreased surviving fractions and Rad51 foci,increased total DNA damage,andγH2AX and 53BP1 foci(P<0.05).The expressions of HR repair proteins were remarkably decreased in olaparib-treated H460 and H1299 cells after irradiation(P<0.05),while olaparib combined with ML216 exerted a synergistic radiosensitization effect on olaparib-resistant A549 cells.In addition to increases of double strand break(DSB)damage and decreases of Rad51 foci,olaparib combined with ML216 also increased pDNA-PKcs(S2056)foci,abrogated G2 cell cycle arrest,and induced apoptosis in A549 lung cancer after irradiation in vitro and in vivo(P<0.05).Moreover,Western blot showed that olaparib combined with ML216 and irradiation inhibited HR repair,promoted NHEJ repair,and inactivated cell cycle checkpoint signals both in vitro and in vivo(P<0.05).Conclusions:Taken together,these results showed the efficacy of PARP and BLM helicase inhibitors for radiosensitizing NSCLC cells,and supported the model that BLM inhibition sensitizes cells to PARP inhibitor-mediated radiosensitization,as well as providing the basis for the potential clinical development of this combination for tumors intrinsically resistant to PARP inhibitors and radiotherapy.

Maternal gene Ooep may participate in homologous recombination-mediated DNA double-strand break repair in mouse oocytes

DNA damage in oocytes can cause infertility and birth defects. DNA double-strand breaks （DSBs） are highly deleterious and can substantially impair genome integrity. Homologous recombination （HR）-mediated DNA DSB repair plays dominant roles in safeguarding oocyte quantity and quality. However, little is known regarding the key players of the HR repair pathway in oocytes. Here, we identified oocyte-specific gene Ooep as a novel key component of the HR repair pathway in mouse oocytes. OOEP was required for efficient ataxia telangiectasia mutated （ATM） kinase activation and Rad51 recombinase （RAD51） focal accumulation at DNA DSBs. Ooep null oocytes were defective in DNA DSB repair and prone to apoptosis upon exogenous DNA damage insults. Moreover, Ooep null oocytes exhibited delayed meiotic maturation. Therefore, OOEP played roles in preserving oocyte quantity and quality by maintaining genome stability. Ooep expression decreased with the advance of maternal age, suggesting its involvement in maternal aging.

The Role of DNA Mismatch Repair and Recombination in the Processing of DNA Alkylating Damage in Living Yeast Cells

It is proposed that mismatch repair (MMR) mediates the cytotoxic effects of DNA damaging agents by exerting a futile repair pathway which leads to double strand breaks (DSBs). Previous reports indicate that the sensitivity of cells defective in homologous recombination (HR) to DNA alkylation is reduced by defects in MMR genes. We have assessed the contribution of different MMR genes to the processing of alkylation damage in vivo. We have directly visualized recombination complexes formed upon DNA damage using fluorescent protein (FP) fusions. We find that msh6 mutants are more resistant than wild type cells to MNNG, and that an msh6 mutation rescues the sensitivity of rad52 strains more efficiently than an msh3 mutation. Analysis of RAD52-GFP tagged strains indicate that MNNG increases repair foci formation, and that the inactivation of the MHS2 and MSH6 genes but not the MSH3 gene result in a reduction of the number of foci formed. In addition, in the absence of HR, NHEJ could process the MNNG-induced DSBs as indicated by the formation of NHEJ-GFP tagged foci. These data suggest that processing of the alkylation damage by MMR, mainly by MSH2-MSH6, is required for recruitment of recombination proteins to the damage site for repair.

基于GSS算法的HRD评分与高危前列腺癌和转移性激素敏感性前列腺癌患者临床病理特征、基因组突变和预后的关系

目的分析同源重组修复缺陷(HRD)评分与高危和转移性激素敏感性前列腺癌(mHSPC)患者临床病理特征、基因组突变的关系及对mHSPC患者预后的预测价值。方法纳入2021年12月—2023年11月在解放军总医院第一医学中心泌尿外科诊治的高危前列腺癌和mHSPC患者127例,进行同源重组修复(HRR)基因测序,并基于基因组疤痕评分(GSS)算法得出HRD评分。分析HRD评分与临床病理特征、基因突变和患者预后之间的关系。结果127例高危前列腺癌和mHSPC患者的中位HRD评分为1.6(0.8,5.2),30例(23.6%)患者HRD评分≥10,11例(8.7%)患者HRD评分≥20。临床病理特征包括国际泌尿病理协会(ISUP)分级≥4(P=0.044)和转移状态(P=0.008)与高HRD评分相关。存在BRCA、TP53和MYC体系基因突变型患者的HRD评分显著高于野生型基因患者(P<0.05)。在mHSPC患者中,HRD评分≥20患者出现生化复发的风险是HRD评分<20患者的12.836倍[OR:12.836(1.332~124.623),P=0.028]。结论HRD评分在高危前列腺癌和mHSPC患者中的基线水平较低;HRD评分高的患者可能倾向于拥有更高的组织学分级(ISUP≥4)和更晚的临床分期。HRD评分作为生化标志物提示不良预后的阈值还需进一步的研究。

Mechanism of RBBP8-mediated homologous recombination repair in gastric cancer synthetic lethal

Background:It is of great clinical significance to further explore new strategies and potential combined therapeutic targets for gastric cancer.This study aimed to investigate the synthetic lethal effect of RBBP8 molecular intervention combined with a poly ADP ribose polymerase(PARP)inhibitor in non-BRCA mutant gastric cancer and clarify the mechanism by which RBBP8 regulates homologous recombination repair.Methods:The role of RBBP8 in DNA damage repair was observed using bioinformatic analysis,western blot analysis,and immunofluorescence.The synthetic lethal effect was verified using 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium,inner salt(MTS)and flow cytometry apoptosis experiments.Results:Among the patients with gastric cancer treated with chemotherapy,the prognosis of patients with high RBBP8 expression levels was worse(homologous recombination[HR]=1.54,p=0.028).RBBP8 knockdown induced DNA damage and had a synergistic effect with PARP inhibitor treatment on cell viability inhibition and cell apoptosis in AGS(generic code for human gastric adenocarcinoma cells)(t=11.154,p<0.001)and N87(t=6.362,p<0.001)cells.RBBP8 knockdown inhibited RAD51 activation and DNA terminal excision in homologous recombination repair.Conclusion:RBBP8 is involved in homologous recombination repair,and molecular intervention into RBBP8 could achieve a synthetic lethal effect with PARP inhibitor treatment in gastric cancer cells.

Patient Assessment and Therapy Planning Based on Homologous Recombination Repair Deficiency

Defects in genes involved in the DNA damage response cause homologous recombination repair deficiency(HRD).HRD is found in a subgroup of cancer patients for several tumor types,and it has a clinical relevance to cancer prevention and therapies.Accumulating evidence has identified HRD as a biomarker for assessing the therapeutic response of tumor cells to poly(ADP-ribose)polymerase inhibitors and platinum-based chemotherapies.Nevertheless,the biology of HRD is complex,and its applications and the benefits of different HRD biomarker assays are controversial.This is primarily due to inconsistencies in HRD assessments and definitions(gene-level tests,genomic scars,mutational signatures,or a combination of these methods)and difficulties in assessing the contribution of each genomic event.Therefore,we aim to review the biological rationale and clinical evidence of HRD as a biomarker.This review provides a blueprint for the standardization and harmonization of HRD assessments.

Characteristics of homologous recombination repair pathway genes mutation in ovarian cancers

Background:Few studies have investigated the characteristics of non‐BRCA homologous recombination repair(HRR)pathway somatic mutations,and the impact of these mutations on efficacy of treatment in ovarian cancer patients is not clear.Therefore,we conducted this study to analyze the frequency and spectrum of somatic mutations in HRR pathway genes in patients with ovarian cancer and to examine the relationships between somatic mutations in HRR pathway genes and their effects on the efficacy of platinum‐based chemotherapy.Methods:We performed targeted sequencing of 688 genes related to the occurrence,development,treatment,and prognosis of solid tumors.Somatic mutations were identified by paired analysis of tumor tissue and germline DNA in blood cells.Results:A total of 38 patients with ovarian cancer were included in the study,and 35(92.1%)patients were diagnosed with high‐grade serous carcinoma.All patients exhibited somatic mutations in the tumor tissue samples.The commonly mutated genes were TP53(73.7%),BRCA2(55.3%),NF1(52.6%),BRCA1(47.4%),and CDH1(47.4%).Overall,71.1%of the patients exhibited mutation in at least one HRR pathway gene.The most frequently altered HRR genes were BRCA2(55.3%),followed by BRCA1(47.4%),ATM(44.7%),BARD1(42.1%),and CHEK1(36.8%).The median progression‐free survival(PFS)in patients with HRR pathway mutation was 36.0 months compared with 13.6 months in patients with no HRR pathway mutation(hazard ratio[HR],0.25;95%confidence interval[CI],0.08–0.77;p=0.016).Patients harboring BRCA1/2 and/or CDK12 mutations displayed a longer PFS(median,36.0 months)compared with patients with no BRCA1/2 or CDK12 mutation(median,13.6 months;HR,0.21;95%CI,0.07–0.61;p=0.004).In multivariate analysis Cox proportional hazards models,after adjustment for tumor stage at diagnosis and histology of initial diagnosis,patients with HRR pathway mutation had a longer PFS than patients with HRR wild‐type genes(p=0.006).Conclusions:HRR pathway somatic mutations are common in Chinese patients with ovarian cancer.HRR pathway somatic mutations were associated with improved sensitivity to platinum-based chemotherapy.Large-scale prospective studies are needed to verify our findings.

Regulation of DNA double-strand break repair pathway choice

DNA double-strand breaks （DSBs） are critical lesions that can result in cell death or a wide variety of genetic alterations including largeor small-scale deletions, loss of heterozygosity, translocations, and chromosome loss. DSBs are repaired by non-homologous end-joining （NHEJ） and homologous recombination （HR）, and defects in these pathways cause genome instability and promote tumorigenesis. DSBs arise from endogenous sources including reactive oxygen species generated during cellular metabolism, collapsed replication forks, and nucleases, and from exogenous sources including ionizing radiation and chemicals that directly or indirectly damage DNA and are commonly used in cancer therapy. The DSB repair pathways appear to compete for DSBs, but the balance between them differs widely among species, between different cell types of a single species, and during different cell cycle phases of a single cell type. Here we review the regulatory factors that regulate DSB repair by NHEJ and HR in yeast and higher eukaryotes. These factors include regulated expression and phosphorylation of repair proteins, chromatin modulation of repair factor accessibility, and the availability of homologous repair templates. While most DSB repair proteins appear to function exclusively in NHEJ or HR, a number of proteins influence both pathways, including the MRE11/RAD50/NBS1（XRS2） complex, BRCA1, histone H2AX, PARP-1, RAD18, DNA-dependent protein kinase catalytic subunit （DNA-PKcs）, and ATM. DNA-PKcs plays a role in mammalian NHEJ, but it also influences HR through a complex regulatory network that may involve crosstalk with ATM, and the regulation of at least 12 proteins involved in HR that are phosphorylated by DNA-PKcs and/or ATM.

原发性卵巢发育不全一家系HROB致病等位基因遗传学分析

一例13岁6个月女童因月经未初潮就诊,实验室检查提示卵泡刺激素及黄体生成素增高,抗米勒管激素降低,盆腔超声未发现双侧卵巢,条索状子宫。进一步完善患儿妹妹检查,与先证者表型类似,可诊断为原发性卵巢发育不全。全外显子组测序及家系桑格测序结果提示,患儿及妹妹均携带HROB基因c.718C>T(p.Arg240*)及c.1351C>T(p.Arg451*)杂合变异,分别遗传自父母亲,符合常染色体隐性遗传规律。先证者予以起始剂量0.125 mg/d戊酸雌二醇口服,半年后第二性征开始发育。

DNA repair and synthetic lethality

Tumors often have DNA repair defects, suggesting additional inhibition of other DNA repair pathways in tumors may lead to synthetic lethality. Accumulating data demonstrate that DNA repair-defective tumors, in particular homologous recombination （HR）, are highly sensitive to DNA-damaging agents. Thus, HR-defective tumors exhibit potential vulnerability to the synthetic lethality approach, which may lead to new therapeutic strategies. It is well known that poly （adenosine diphosphate （ADP）-ribose） polymerase （PARP） inhibitors show the synthetically lethal effect in tumors defective in BRCA1 or BRCA2 genes encoded proteins that are required for efficient HR. In this review, we summarize the strategies of targeting DNA repair pathways and other DNA metabolic functions to cause synthetic lethality in HR-defective tumor cells.

携带HR-GFP报告基因的DNA损伤同源重组修复检测系统的建立及初步应用

目的建立DNA损伤同源重组修复检测系统(Ⅰ-Sce I-HR),应用该系统制备DNA双链断裂(DSB)的人骨肉瘤细胞(U2OS)模型,探索细胞DNA损伤后的修复特性奠定基础。方法通过分子克隆构建携带Ⅰ-Sce I归位内切酶识别序列的真核表达载体pcDNA3-HR-GFP,将该质粒转染入U2OS细胞中,经G418稳定筛选。随后分别瞬时转染入携带归位内切酶Ⅰ-Sce I的表达质粒pCBASCEI,以及体外经Ⅰ-Sce I线性化pcDNA3-HR-GFP。48小时后用免疫荧光方法检测DNA双链损伤效应分子-γ-H2AX,同时观察EGFP荧光信号;72小时后用Western blot检测报告蛋白EGFP的表达,评估DNA双链断裂后同源重组修复情况。结果酶切鉴定和测序证实pcDNA3-HR-GFP真核表达载体构建成功;Ⅰ-Sce I-HR系统引入U2OS细胞中后,γ-H2AX表达明显上调,荧光显微镜和Western blot均显示EGFP表达。结论 DSB细胞同源重组修复模型构建成功,Ⅰ-Sce I-HR系统能够成功地诱导U2OS细胞株产生DSB,并出现同源重组修复,为进一步研究DNA同源重组信号传导提供了有效的研究工具。

New insights into tumor dormancy:Targeting DNA repair pathways

Over the past few decades, major strides have advanced the techniques for early detection and treatment of cancer. However, metastatic tumor growth still accounts for the majority of cancer-related deaths worldwide. In fact, breast cancers are notorious for relapsing years or decades after the initial clinical treatment, and this relapse can vary according to the type of breast cancer. In estrogen receptor-positive breast cancers, late tumor relapses frequently occur whereas relapses in estrogen receptor-negative cancers or triple negative tumors arise early resulting in a higher mortality risk. One of the main causes of metastasis is tumor dormancy in which cancer cells remain concealed, asymptomatic, and untraceable over a prolonged period of time. Under certain conditions, dormant cells can re-enter into the cell cycle and resume proliferation leading to recurrence. However, the molecular and cellular regulators underlying this transition remain poorly understood. To date, three mechanisms have been identified to trigger tumor dormancy including cellular, angiogenic, and immunologic dormancies. In addition, recent studies have suggested that DNA repair mechanisms may contribute to the survival of dormant cancer cells. In this article, we summarize the recent experimental and clinical evidence governing cancer dormancy. In addition, we will discuss the role of DNA repair mechanisms in promoting the survival of dormant cells. This information provides mechanistic insight to explain why recurrence occurs, and strategies that may enhance therapeutic approaches to prevent disease recurrence.

靶向抑制高表达HRR蛋白增强肿瘤细胞对放化疗的敏感性

同源重组修复(HRR)主要通过修复哺乳动物细胞中外源或内源性的DNA双链断裂,维持正常细胞基因组的完整性与稳定性,从而阻止细胞癌变。有研究发现高表达HRR蛋白的肿瘤细胞具有较强的损伤修复活力,通过修复放化疗诱导的DNA损伤,抑制凋亡途径以及活化细胞增殖信号通路,使其对放化疗产生耐受性,肿瘤细胞得以存活。这类HRR蛋白在肿瘤细胞中起到了癌基因的功效,维持了肿瘤细胞基因组的稳定性,促进了肿瘤的发生、发展,因而肿瘤细胞中高表达的HRR蛋白成为了肿瘤精准化治疗的潜在靶点。通过药物诱导HRR蛋白过度表达不仅能促进肿瘤细胞的凋亡,而且可以进一步提高肿瘤细胞对放化疗的敏感性。

非小细胞肺癌组织EMSY、PIDD表达与同源重组修复基因的相关性及其临床意义

目的研究非小细胞肺癌(NSCLC)组织中EMSY转录抑制因子(EMSY)、p53诱导的死亡结构域蛋白1(PIDD)表达与同源重组修复基因表达的相关性及临床意义。方法选择2022年1月—2023年4月河北北方学院附属第一医院呼吸与危重症医学科诊治NSCLC患者80例。采用实时荧光定量PCR检测癌组织及癌旁组织中EMSY、PIDD表达与同源重组修复基因人乳腺癌易感基因1(BRCA1)、切除修复交叉互补基因1(ERCC1),核糖核苷酸还原酶亚单位1(RRM1)表达。Pearson相关分析EMSY、PIDD表达与同源重组修复基因表达的相关性;分析EMSY、PIDD表达与NSCLC临床病理相关参数的关系及在NSCLC诊断中的价值。结果NSCLC癌组织中EMSY、PIDD、BRCA1、ERCC1、RRM1 mRNA相对表达量均高于癌旁组织(t/P=30.176/<0.001,27.821/<0.001,25.075/<0.001,16.680/<0.001,25.610/<0.001)。NSCLC癌组织中EMSY、PIDD mRNA与BRCA1、ERCC1、RRM1 mRNA表达均呈正相关(r/P=0.654/<0.001,0.712/<0.001,0.584/<0.001;0.724/<0.001,0.661/<0.001,0.563/<0.001)。低分化程度、有淋巴结转移及TNM分期Ⅲ期NSCLC癌组织EMSY、PIDD mRNA表达分别显著高于高中分化程度、无淋巴结转移及TNM分期Ⅰ~Ⅱ期NSCLC癌组织(t/P=13.693/<0.001,13.380/<0.001,12.197/<0.001;10.289/<0.001,11.130/<0.001,9.405/<0.001)。EMSY、PIDD mRNA及两项联合诊断NSCLC的AUC分别为0.834、0.802、0.906,两项联合诊断的AUC大于单一指标(Z=4.751、5.257,P均<0.001)。结论EMSY、PIDD在NSCLC癌组织中表达升高,与同源重组修复基因表达及不良临床病理特征有关,两者联合有助于NSCLC的诊断。

同源重组修复基因突变对晚期非小细胞肺癌患者免疫治疗疗效和预后的影响

目的:探讨同源重组修复(HRR)基因突变对晚期非小细胞肺癌(NSCLC)患者免疫治疗疗效和预后的影响。方法:收集2018年3月至2023年4月间在郑州大学第一附属医院接受PD-1抑制剂治疗的124例晚期NSCLC患者的临床资料。根据有无HRR基因突变将患者分为突变组(n=57例)和野生组(n=67例),采用卡方检验或Fisher’s精确检验比较两组患者的临床特征及免疫治疗疗效差异,采用Kaplan-Meier方法比较两组患者的PFS,采用单因素和多因素Cox回归分析PFS的影响因素。结果:HRR基因突变组中鳞癌及肿瘤突变负荷(TMB)≥10 mut/Mb的占比显著多于野生组(54.4%vs 32.8%,61.4%vs 29.9%,均P<0.05)。HRR基因突变组与野生组患者的ORR分别为17.5%和10.4%(P=0.252),DCR分别为86.0%和73.1%(P=0.080)。HRR基因突变组与野生组的PFS比较差异具有统计学意义(6.8个月vs 3.9个月,P<0.001)。多因素分析结果显示,有无HRR基因突变[HR=0.550,95%CI(0.352,0.860),P=0.009]与免疫治疗线数[HR=0.468,95%CI(0.312,0.702),P<0.001]和PFS显著相关。结论:HRR基因突变组患者的免疫治疗疗效优于野生组患者,HRR基因突变是晚期NSCLC患者免疫治疗预后的独立保护因素。

植物DNA双链断裂修复机制及其在重离子诱变和基因编辑中的作用

在自然界中,植物会遭受各种环境或内源因素导致的DNA损伤,其中DNA双链断裂(double strand breaks,DSBs)的影响最为严重,如果修复不当,将导致基因组不稳定、基因突变甚至细胞死亡。一方面,植物进化出了强大且有序的损伤修复机制,以确保其存活及正常繁衍;另一方面,基于修复过程的容错性及致突变性,T-DNA插入、基因编辑、物理诱变等技术广泛应用于动植物品种改良。相较于哺乳动物,植物DSBs修复通路及其分子机制报道较为有限。本文综述了植物对DSBs损伤的响应、主要修复途径及关键因子,介绍了通路机制尚未完全解析的替代末端连接(alternative end joining,Alt-EJ)的最新研究进展;此外,探讨了重离子束引起的植物DSBs修复特征和多途径选择,以及基于不同DSBs修复途径的基因编辑技术的研究进展,旨在为深入了解植物DSBs损伤响应及修复的分子机制和研发高效生物育种技术提供参考。

马里苷靶向p38α增强卵巢癌细胞对DNA损伤药物敏感度的研究

目的探究马里苷抑制同源重组修复,联合使用DNA损伤药物的疗效以及其机制。方法CCK-8法、克隆集落形成实验、类器官药敏实验检验细胞和类器官在联合用药后的增敏情况;Western blot法、彗星实验以及同源重组修复报告基因检测细胞联合用药后的DNA损伤情况及其抑制同源重组修复的机制;细胞热转移实验和药物亲和反应的靶点稳定性技术验证马里苷与p38α的结合情况。结果马里苷与p38α结合增加了癌细胞和类器官对DNA损伤药物的敏感度;马里苷抑制p-p38α,增加癌细胞的DNA损伤,抑制癌细胞同源重组修复。结论马里苷抑制同源重组修复,增强了癌细胞对DNA损伤药物的敏感度,从而为卵巢癌的临床用药提供了新策略。