核苷酸切除修复基因多态性和铂类药物耐药性关系研究进展

铂类药物广泛用于实体肿瘤的化疗,其作用机制与肿瘤细胞DNA的损伤有关,然而,机体的DNA修复机制可以将这些损伤修复.核苷酸切除修复是DNA修复中的一种,目前认为核苷酸切除修复与铂类药物的耐药相关.本文就核苷酸切除修复基因多态性和铂类药物耐药性关系研究进展作一综述.     

核苷酸切除修复与铂类耐药研究进展

目前肿瘤化疗仍以肿瘤发生部位和病理类型为基础选择药物,由于肿瘤本身以及个体之间存在异质性,相同部位和相同病理类型的肿瘤对化疗敏感性存在差异。长期以来,人们追求根据肿瘤自身药物敏感性开展个体化治疗。近年来,药物敏感相关基因检测获得快速发展,使个体化化疗成为可能。在相关基因与化疗药物研究领域中,核苷酸切除修复基因与铂类药物研究是最受瞩目的内容之一。1铂类药物耐药机制铂类药物(顺铂、卡铂、草酸铂)是临床上最常用的一类化疗药物。铂类药物进入肿瘤细胞后与DNA结合,形成Pt-DNA加合物,导致DNA的链间或链内交链,引起DNA复制障碍,从而抑制肿瘤细胞分裂。铂类药物的耐药机制主要有减少药物摄取积聚、通过共扼结合去除药物毒性、提高对铂类药物诱导产生的DNA加合物的耐受性及提高DNA修复能力等。研究证实,临床缓解率与循环中Pt-DNA加合物的水平相关,如果肿瘤细胞DNA修复能力减低,就会导致Pt-DNA加合物清除减少,使患者对铂类药物的疗效提高,反之疗效则差。因此,DNA修复能力是影响铂类药物疗效的主要原因。DNA切除修复途径主要有碱基切除修复(base-exc ision repair,BER)、DNA双链断裂修复(DN...     

DNA修复基因单核苷酸多态性预测铂类药物敏感性和预后

铂类药物是治疗实体肿瘤常用的药物之一,但是肿瘤细胞对铂类药物耐药导致化疗失败,成为临床治疗的一大难题。DNA修复能力是影响疗效的重要原因。DNA修复基因单核苷酸多态性(SNP)可改变DNA修复能力,因此,检测这些基因的单核苷酸多态性可以预测疗效。现综述DNA修复基因单核苷酸多态性预测铂类药物敏感性和预后的研究进展。     

XPD单核苷酸多态性与肺癌化疗敏感性及预后关系的研究进展

肿瘤的耐药导致患者对化疗敏感性降低是化疗失败的主要原因。如何预见肿瘤患者对化疗的敏感性、并及时发现肿瘤耐药,是目前肿瘤化疗急需解决的问题。研究发现,肿瘤细胞对铂类药物化疗的敏感性与机体DNA修复能力密切相关,而着色性干皮病基因D(XPD)单核苷酸多态性与DNA修复能力的改变有关,预测XPD多态性可以作为一个判断肿瘤患者铂类药物化疗敏感性的指标。     

大肠癌对铂类药物的耐药机制

铂类药物是大肠癌化疗常用的药物之一,但仍存在耐药问题而影响疗效,因此研究肿瘤细胞的铂类耐药机制是大肠癌治疗研究的热点,包括药物蓄积降低、DNA修复机制、形态学变化等.     

卵巢癌铂类耐药标志物的研究进展

摘 要：卵巢癌是女性三大恶性肿瘤之一,其死亡率位于妇科癌症之首。铂类联合紫杉醇是卵巢癌术后一线化疗方案,但约75%晚期患者对铂类药物耐药。铂类耐药标志物能预测患者对铂类药物的反应,指导卵巢癌患者治疗药物的选择。本篇综述按靶前、靶点、靶后和靶外标志物四个方面对近几年的卵巢癌铂类耐药标志物的研究成果进行归纳并简单阐述其相应的耐药机制。     

TTK1在卵巢癌铂类耐药中的生物学功能分析

背景与目的:苏氨酸酪氨酸激酶1(threonine tyrosine kinase 1,TTK1)是纺锤体组装检查点的一个组成部分,确保染色体的正确分离,可能是与化疗敏感性相关的潜在目标分子,但TTK1在铂类药物耐药方面的作用机制仍不清楚.卵巢癌是女性常见的生殖系统恶性肿瘤之一,发病率在妇科恶性肿瘤中排名第三,死亡率排...     

卵巢上皮癌铂类耐药与非耐药细胞间核苷酸切除修复基因多态性的检测

目的:探讨卵巢上皮癌铂类耐药与非耐药细胞间核苷酸切除修复基因(ERCC1、XPA、XPC、XPD、XPG)多态性遗传的差异表达.方法:应用PCR及测序方法筛查ERCC1、XPA、XPC、XPD、XPG外显子单核苷酸多态性在卵巢癌耐铂类药物的细胞株和敏感细胞株中的分布差异,序列读解采用ChromaS软件,并结合 NCBISNP数据库寻找和验证SNP位点.结果:DNA测序分析发现XPG His46His及XPGHis1104Asp两个SNP位点在细胞系中存在分布差异.结论:核苷酸切除修复系统中XPGHis46His及XPG His1104Asp多态表达可能与卵巢癌患者对铂类药物耐药性相关.     

脂质代谢重编程对卵巢癌铂耐药影响的研究进展

卵巢癌是女性致死率最高的恶性肿瘤，晚期患者5年生存率不足50%。以铂类药物为主的化疗是晚期卵巢癌的主要治疗策略，多数患者初期铂类化疗敏感，然而大约80%的铂敏感患者经多次化疗后对铂类产生耐药。与其他上皮性肿瘤不同，卵巢癌的转移方式以向脂肪细胞丰富的大网膜转移为主，这一特殊的转移偏好为寻找脂质代谢相关铂耐药机制的研究提供了新思路。因此，本文综述了胆固醇及脂肪酸两大脂类物质代谢对卵巢癌铂耐药影响的研究进展，以期为改善卵巢癌患者预后，找到规避甚至逆转铂耐药的生物标志物及药物靶点提供新的线索。     

DNA损伤修复与肺癌顺铂耐药机制的研究进展

肺癌是目前世界上致死率最高的恶性肿瘤,化疗是治疗的主要手段之一,肺癌的化疗是以铂类为基础的联合化疗,其中,顺铂是有效并广泛应用的一线药物,但是由于耐药问题的存在使其疗效不尽如人意。顺铂是一种细胞周期非特异性细胞毒药物,其主要作用靶点是DNA,因此DNA损伤修复功能的异常是顺铂耐药的主要机制之一。本文主要综述了与肺癌顺铂耐药相关的DNA损伤修复异常,包括核苷酸切除修复异常、碱基错配修复异常、DNA双链断裂损伤修复异常及跨损伤修复。     

Telomeric allelic imbalance indicates defective DNA repair and sensitivity to DNA-damaging agents

DNA repair competency is one determinant of sensitivity to certain chemotherapy drugs, such as cisplatin. Cancer cells with intact DNA repair can avoid the accumulation of genome damage during growth and also can repair platinum-induced DNA damage. We sought genomic signatures indicative of defective DNA repair in cell lines and tumors and correlated these signatures to platinum sensitivity. The number of subchromosomal regions with allelic imbalance extending to the telomere (N(tAI)) predicted cisplatin sensitivity in vitro and pathologic response to preoperative cisplatin treatment in patients with triple-negative breast cancer (TNBC). In serous ovarian cancer treated with platinum-based chemotherapy, higher levels of N(tAI) forecast a better initial response. We found an inverse relationship between BRCA1 expression and N(tAI) in sporadic TNBC and serous ovarian cancers without BRCA1 or BRCA2 mutation. Thus, accumulation of telomeric allelic imbalance is a marker of platinum sensitivity and suggests impaired DNA repair. SIGNIFICANCE: Mutations in BRCA genes cause defects in DNA repair that predict sensitivity to DNA damaging agents, including platinum; however, some patients without BRCA mutations also benefit from these agents. NtAI, a genomic measure of unfaithfully repaired DNA, may identify cancer patients likely to benefit from treatments targeting defective DNA repair.     

Targeting DNA Repair in Ovarian Cancer Treatment Resistance

Most patients with advanced high-grade serous ovarian cancer (HGSOC) develop recurrent disease within 3 years and succumb to the disease within 5 years. Standard treatment for HGSOC is cytoreductive surgery followed by a combination of platinum (carboplatin or cisplatin) and taxol (paclitaxel) chemotherapies. Although initial recurrences are usually platinum-sensitive, patients eventually develop resistance to platinum-based chemotherapy. Accordingly, one of the major problems in the treatment of HGSOC and disease recurrence is the development of chemotherapy resistance. One of the causes of chemoresistance may be redundancies in the repair pathways involved in the response to DNA damage caused by chemotherapy. These pathways may be acting in parallel, where if the repair pathway that is responsible for triggering cell death after platinum chemotherapy therapy is deficient, an alternative repair pathway compensates and drives cancer cells to repair the damage, leading to chemotherapy resistance. In addition, if the repair pathways are epigenetically inactivated by DNA methylation, cell death may not be triggered, resulting in accumulation of mutations and DNA damage. There are novel and existing therapies that can drive DNA repair pathways towards sensitivity to platinum chemotherapy or targeted therapy, thus enabling treatment-resistant ovarian cancer to overcome chemotherapy resistance.     

The RNA polymerase I transcription inhibitor CX-5461 cooperates with topoisomerase 1 inhibition by enhancing the DNA damage response in homologous recombination-proficient high-grade serous ovarian cancer

Background Intrinsic and acquired drug resistance represent fundamental barriers to the cure of high-grade serous ovarian carcinoma (HGSC), the most common histological subtype accounting for the majority of ovarian cancer deaths. Defects in homologous recombination (HR) DNA repair are key determinants of sensitivity to chemotherapy and poly-ADP ribose polymerase inhibitors. Restoration of HR is a common mechanism of acquired resistance that results in patient mortality, highlighting the need to identify new therapies targeting HR-proficient disease. We have shown promise for CX-5461, a cancer therapeutic in early phase clinical trials, in treating HR-deficient HGSC.Methods Herein, we screen the whole protein-coding genome to identify potential targets whose depletion cooperates with CX-5461 in HR-proficient HGSC.Results We demonstrate robust proliferation inhibition in cells depleted of DNA topoisomerase 1 (TOP1). Combining the clinically used TOP1 inhibitor topotecan with CX-5461 potentiates a G2/M cell cycle checkpoint arrest in multiple HR-proficient HGSC cell lines. The combination enhances a nucleolar DNA damage response and global replication stress without increasing DNA strand breakage, significantly reducing clonogenic survival and tumour growth in vivo.Conclusions Our findings highlight the possibility of exploiting TOP1 inhibition to be combined with CX-5461 as a non-genotoxic approach in targeting HR-proficient HGSC.Subject terms: Targeted therapies, Ovarian cancer     

The E3 ubiquitin ligase EDD is an adverse prognostic factor for serous epithelial ovarian cancer and modulates cisplatin resistance in vitro

Despite a high initial response rate to first-line platinum/paclitaxel chemotherapy, most women with epithelial ovarian cancer relapse with recurrent disease that becomes refractory to further cytotoxic treatment. We have previously shown that the E3 ubiquitin ligase, EDD, a regulator of DNA damage responses, is amplified and overexpressed in serous ovarian carcinoma. Given that DNA damage pathways are linked to platinum resistance, the aim of this study was to determine if EDD expression was associated with disease recurrence and platinum sensitivity in serous ovarian cancer. High nuclear EDD expression, as determined by immunohistochemistry in a cohort of 151 women with serous ovarian carcinoma, was associated with an approximately two-fold increased risk of disease recurrence and death in patients who initially responded to first-line chemotherapy, independently of disease stage and suboptimal debulking. Although EDD expression was not directly correlated with relative cisplatin sensitivity of ovarian cancer cell lines, sensitivity to cisplatin was partially restored in platinum-resistant A2780-cp70 ovarian cancer cells following siRNA-mediated knockdown of EDD expression. These results identify EDD as a new independent prognostic marker for outcome in serous ovarian cancer, and suggest that pathways involving EDD, including DNA damage responses, may represent new therapeutic targets for chemoresistant ovarian cancer.     

Gene-specific repair of Pt/DNA lesions and induction of apoptosis by the oral platinum drug JM216 in three human ovarian carcinoma cell lines sensitive and resistant to cisplatin

JM216, an oral platinum drug entering into phase III clinical trial, exhibited comparable cytotoxicity to cisplatin in three human ovarian carcinoma cell lines: the sensitive (CH1), acquired resistant (CH1cisR) and intrinsically resistant (SKOV-3). Platinum accumulation and binding to DNA were similar in each of the three cell lines at equimolar doses, indicating that the resistant cell lines could tolerate higher intracellular platinum levels and platinum bound to DNA at IC50 concentrations of drug. Comparison with cisplatin demonstrated that intracellular platinum levels were marginally higher with JM216, but that platinum binding to DNA was similar for the two drugs in each of the cell lines. Each of the cell lines exhibited an ability to repair JM216 induced platinum/DNA lesions in the N-ras gene (gene-specific repair) at equitoxic concentrations of drug. However, this occurred to a greater extent in the two resistant cell lines such that by 24 h the CH1cisR and SKOV-3 had removed 72% and 67% respectively compared with approximately 32% for the CH1. Reduced gene-specific repair capacity in CH1 cells was also seen following incubation with 25 microM (or 5 microM - 2 x IC50) cisplatin, whereas the CH1cisR and SKOV-3 cell lines were repair proficient. JM216 induced apoptosis in the three cell lines following a 2h incubation with 2 x the IC50 of drug. Fluorescent microscopy of cells stained with propidium iodide showed that the detached cell population displayed typical apoptotic nuclei. Furthermore, field inversion gel electrophoresis demonstrated the presence of DNA fragments approximately 23-50 kb in size, indicative of apoptosis, in the detached cells. JM216 induced an S phase slow down in each of the three cell lines accompanied by a G2 block in the CH1 pair. Incubation with this concentration of JM216 also resulted in the induction of p53 in the CH1 and CH1cisR. These studies suggest that the relative sensitivity of the CH1 cell line to cisplatin and JM216 is at least partly attributable to a deficiency in gene-specific repair. The oral platinum drug, JM216, exerts its cytotoxic effects through the induction of apoptosis following a slow-down in S phase in both the sensitive and resistant lines.     

Enhanced cisplatin cytotoxicity by disturbing the nucleotide excision repair pathway in ovarian cancer cell lines

Ovarian cancer is the leading cause of death among women from gynecological malignancies inthe United States. Resistance to the chemotherapeutic agent cisplatin isa major limitation for the successful treatment of ovarian cancer. In an effort to overcome the cisplatin resistance problem in ovarian cancer treatment, we have sought to enhance cisplatin cytotoxicity by perturbing the nucleotide excision repair (NER) pathway. The NER pathway is responsible for repairing cisplatin bound to DNA. Expression of one of the NER components, ERCC1, is correlated with cisplatin drug resistance. Hence, we targeted ERCC1 by antisense RNA methodologies, and we show that we could sensitize a relatively sensitive A2780 cell line and also the highly resistant OVCAR10 cell line to cisplatin by expressing antisense ERCC1 RNA in them as measured with 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays. The A2780 cell lines expressing antisense ERCC1 had 1.9-8.1-fold enhancements in cisplatin sensitivity. The OVCAR10 antisense ERCC1 cell lines had IC(50) values ranging from 2.28 microM to 2.7 microM cisplatin as compared with 9.52 micro M for control OVCAR10 cells. The OVCAR10 antisense ERCC1 cells also show reduced DNA-damage repair capacity as assessed by host cell reactivation. Furthermore, immunocompromised mice transplanted with the antisense cell lines survived longer than the mice bearing control cells after response to cisplatin treatment. These data suggest that it is possible to substantially enhance the cisplatin cytotoxicity by disturbing the NER pathway in cisplatin-resistant cell lines and to enhance the survival capacity of mice in an ovarian cancer xenograft model.     

Identification of genes associated with platinum drug sensitivity and resistance in human ovarian cancer cells

Platinum-based chemotherapeutic regimens are ultimately unsuccessful due to intrinsic or acquired drug resistance. Understanding the molecular basis for platinum drug sensitivity/resistance is necessary for the development of new drugs and therapeutic regimens. In an effort to identify such determinants, we evaluated the expression of approximately 4000 genes using cDNA microarray screening in a panel of 14 unrelated human ovarian cancer cell lines derived from patients who were either untreated or treated with platinum-based chemotherapy. These data were analysed relative to the sensitivities of the cells to four platinum drugs (cis-diamminedichloroplatinum (cisplatin), carboplatin, DACH-(oxalato)platinum (II) (oxaliplatin) and cis-diamminedichloro (2-methylpyridine) platinum (II) (AMD473)) as well as the proliferation rate of the cells. Correlation analysis of the microarray data with respect to drug sensitivity and resistance revealed a significant association of Stat1 expression with decreased sensitivity to cisplatin (r=0.65) and AMD473 (r=0.76). These results were confirmed by quantitative RT-PCR and Western blot analyses. To study the functional significance of these findings, the full-length Stat1 cDNA was transfected into drug-sensitive A2780 human ovarian cancer cells. The resulting clones that exhibited increased Stat1 expression were three- to five-fold resistant to cisplatin and AMD473 as compared to the parental cells. The effect of inhibiting Jak/Stat signalling on platinum drug sensitivity was investigated using the Janus kinase inhibitor, AG490. Pretreatment of platinum-resistant cells with AG490 resulted in significant increased sensitivity to AMD473, but not to cisplatin or oxaliplatin. Overall, the results indicate that cDNA microarray analysis may be used successfully to identify determinants of drug sensitivity/resistance and future functional studies of other candidate genes from this database may lead to an increased understanding of the drug resistance phenotype.     

Differential contributory roles of nucleotide excision and homologous recombination repair for enhancing cisplatin sensitivity in human ovarian cancer cells

Background  

While platinum-based chemotherapeutic agents are widely used to treat various solid tumors, the acquired platinum resistance is a major impediment in their successful treatment. Since enhanced DNA repair capacity is a major factor in conferring cisplatin resistance, targeting of DNA repair pathways is an effective stratagem for overcoming cisplatin resistance. This study was designed to delineate the role of nucleotide excision repair (NER), the principal mechanism for the removal of cisplatin-induced DNA intrastrand crosslinks, in cisplatin resistance and reveal the impact of DNA repair interference on cisplatin sensitivity in human ovarian cancer cells.     

Targeting superoxide dismutase 1 to overcome cisplatin resistance in human ovarian cancer

Purpose  Clinical drug resistance to platinum-based chemotherapy is considered a major impediment in the treatment of human ovarian cancer. Multiple pathways associated with drug resistance have been suggested by many previous studies. Over expression of several key proteins involved in DNA repair, drug transport, redox regulation, and apoptosis has been recently reported by our group using a global quantitative proteomic profiling approach. Superoxide dismutase 1 (SOD1) is one of these proteins consistently over-expressed in cisplatin-resistant ovarian cancer cells as compared to their sensitive counterparts, but its precise role in drug resistance is yet to be defined. Method  In the current study, we examined the role of SOD1 in drug resistance by inhibiting its redox activity in cisplatin-resistant ovarian cancer cells using a small-molecule inhibitor, triethylenetetramine (TETA). The effect of TETA was determined by the cell proliferation assay, clonogenic cell survival assay, and SOD1 activity assay. Results  The inhibition of the SOD1 activity enhanced the cisplatin sensitivity in the resistant cells supporting the hypothesis that SOD1 is a key determinant of cisplatin resistance and is an exploitable target to overcome cisplatin drug resistance. Conclusion  SOD1 plays an important role in cisplatin resistance and modulation of its activity may overcome this resistance and ultimately lead to improved clinical outcomes.