BRCA1 and XRCC1 polymorphisms associated with survival in advanced gastric cancer treated with taxane and cisplatin

Ailanthus Altissima-derived Ailanthone enhances Gastric Cancer Cell Apoptosis by Inducing the Repression of Base Excision Repair by Downregulating p23 Expression

Chemotherapy plays an irreplaceable role in the treatment of GC, but currently available chemotherapeutic drugs are not ideal. The application of medicinal plants is an important direction for new drug discovery. Through drug screening of GC organoids, we determined that ailanthone has an anticancer effect on GC cells in vitro and in vivo. We also found that AIL can induce DNA damage and apoptosis in GC cells. Further transcriptome sequencing of PDX tissue indicated that AIL inhibited the expression of XRCC1, which plays an important role in DNA damage repair, and the results were also confirmed by western blotting. In addition, we found that AIL inhibited the expression of P23 and that inhibition of P23 decreased the expression of XRCC1, indicating that AIL can regulate XRCC1 via P23. The results of coimmunoprecipitation showed that AIL can inhibit the binding of P23 and XRCC1 to HSP90. These findings indicate that AIL can induce DNA damage and apoptosis in GC cells. Meanwhile, AIL can decrease XRCC1 activity by downregulating P23 expression to inhibit DNA damage repair. The present study sheds light on the potential application of new drugs isolated from natural medicinal plants for GC therapy.

Identification and Validation of SNP-Containing Genes With Prognostic Value in Gastric Cancer via Integrated Bioinformatics Analysis

Background

Gastric cancer is one of the most common malignancies worldwide. Although the diagnosis and treatment of this disease have substantially improved in recent years, the five-year survival rate of gastric cancer is still low due to local recurrence and distant metastasis. An in-depth study of the molecular pathogenesis of gastric cancer and related prognostic markers will help improve the quality of life and prognosis of patients with this disease. The purpose of this study was to identify and verify key SNPs in genes with prognostic value for gastric cancer.

Methods

SNP-related data from gastric cancer patients were obtained from The Cancer Genome Atlas (TCGA) database, and the functions and pathways of the mutated genes were analyzed using DAVID software. A protein-protein interaction (PPI) network was constructed using the STRING database and visualized by Cytoscape software, and molecular complex detection (MCODE) was used to screen the PPI network to extract important mutated genes. Ten hub genes were identified using cytoHubba, and the expression levels and the prognostic value of the central genes were determined by UALCAN and Kaplan-Meier Plotter. Finally, quantitative PCR and Western blotting were used to verify the expression of the hub genes in gastric cancer cells.

Results

From the database, 945 genes with mutations in more than 25 samples were identified. The PPI network had 360 nodes and 1616 edges. Finally, cytoHubba identified six key genes (TP53, HRAS, BRCA1, PIK3CA, AKT1, and SMARCA4), and their expression levels were closely related to the survival rate of gastric cancer patients.

Conclusion

Our results indicate that TP53, HRAS, BRCA1, PIK3CA, AKT1, and SMARCA4 may be key genes for the development and prognosis of gastric cancer. Our research provides an important bioinformatics foundation and related theoretical foundation for further exploring the molecular pathogenesis of gastric cancer and evaluating the prognosis of patients.

Prognostic Value of Two Polymorphisms, rs1045642 and rs1128503, in ABCB1 Following Taxane-based Chemotherapy: A Meta-Analysis

Objective:

Genetic polymorphisms can influence the chemotherapeutic response; however, previous studies have produced conflicting results, and have failed to identify the most relevant polymorphisms for predicting the response to treatment in patients with cancer. The present meta-analysis was conducted to determine the correlation between two polymorphisms (rs1045642 and rs1128503) in ATP-binding cassette transporter B subfamily member 1 (ABCB1), which is associated with multidrug resistance, and the survival of patients treated with taxane-containing chemotherapy.

Methods:

Several databases, including PubMed and Embase, were used to retrieve articles evaluating the association between the ABCB1 rs1045642 and rs1128503 polymorphisms and survival, published prior to August 2019. The meta-analysis was conducted using R software to determine the pooled hazard ratio (HR) and 95% confidence intervals (95% CIs).

Results:

Fifteen studies involving 3320 patients were included in the meta-analysis. The effect of the rs1128503 polymorphism on progression-free survival remained significant in the heterozygote (HR 0.81; 95% CI: 0.67–0.98) and homozygote (HR 0.71; 95% CI: 0.58–0.88) models. The TT genotype rs1128503 was associated with better overall survival (HR 0.72; 95% CI: 0.53–0.97).

Conclusion:

Carriers of the rs1128503 T allele of ABCB1 showed a survival benefit after taxane-containing chemotherapy.

Establishment of Acquired Cisplatin Resistance in Ovarian Cancer Cell Lines Characterized by Enriched Metastatic Properties with Increased Twist Expression

Ovarian cancer (OC) is the most lethal of the gynecologic cancers, and platinum-based treatment is a part of the standard first-line chemotherapy regimen. However, rapid development of acquired cisplatin resistance remains the main cause of treatment failure, and the underlying mechanism of resistance in OC treatment remains poorly understood. Faced with this problem, our aim in this study was to generate cisplatin-resistant (CisR) OC cell models in vitro and investigate the role of epithelial–mesenchymal transition (EMT) transcription factor Twist on acquired cisplatin resistance in OC cell models. To achieve this aim, OC cell lines OV-90 and SKOV-3 were exposed to cisplatin using pulse dosing and stepwise dose escalation methods for a duration of eight months, and a total of four CisR sublines were generated, two for each cell line. The acquired cisplatin resistance was confirmed by determination of 50% inhibitory concentration (IC₅₀) and clonogenic survival assay. Furthermore, the CisR cells were studied to assess their respective characteristics of metastasis, EMT phenotype, DNA repair and endoplasmic reticulum stress-mediated cell death. We found the IC₅₀ of CisR cells to cisplatin was 3–5 times higher than parental cells. The expression of Twist and metastatic ability of CisR cells were significantly greater than those of sensitive cells. The CisR cells displayed an EMT phenotype with decreased epithelial cell marker E-cadherin and increased mesenchymal proteins N-cadherin and vimentin. We observed that CisR cells showed significantly higher expression of DNA repair proteins, X-ray repair cross-complementing protein 1 (XRCC1) and poly (ADP-ribose) polymerases 1 (PARP1), with significantly reduced endoplasmic reticulum (ER) stress-mediated cell death. Moreover, Twist knockdown reduced metastatic ability of CisR cells by suppressing EMT, DNA repair and inducing ER stress-induced cell death. In conclusion, we highlighted the utilization of an acquired cisplatin resistance model to identify the potential role of Twist as a therapeutic target to reverse acquired cisplatin resistance in OC.

Molecular Bases of Mechanisms Accounting for Drug Resistance in Gastric Adenocarcinoma

Gastric adenocarcinoma (GAC) is the most common histological type of gastric cancer, the fifth according to the frequency and the third among the deadliest cancers. GAC high mortality is due to a combination of factors, such as silent evolution, late clinical presentation, underlying genetic heterogeneity, and effective mechanisms of chemoresistance (MOCs) that make the available antitumor drugs scarcely useful. MOCs include reduced drug uptake (MOC-1a), enhanced drug efflux (MOC-1b), low proportion of active agents in tumor cells due to impaired pro-drug activation or active drug inactivation (MOC-2), changes in molecular targets sensitive to anticancer drugs (MOC-3), enhanced ability of cancer cells to repair drug-induced DNA damage (MOC-4), decreased function of pro-apoptotic factors versus up-regulation of anti-apoptotic genes (MOC-5), changes in tumor cell microenvironment altering the response to anticancer agents (MOC-6), and phenotypic transformations, including epithelial-mesenchymal transition (EMT) and the appearance of stemness characteristics (MOC-7). This review summarizes updated information regarding the molecular bases accounting for these mechanisms and their impact on the lack of clinical response to the pharmacological treatment currently used in GAC. This knowledge is required to identify novel biomarkers to predict treatment failure and druggable targets, and to develop sensitizing strategies to overcome drug refractoriness in GAC.

The Impact of the Genetic Polymorphism in DNA Repair Pathways on Increased Risk of Glioblastoma Multiforme in the Arab Jordanian Population: A Case-Control Study

Introduction

Among the Jordanian population, brain tumors are the tenth most common type of cancers in both males and females, comprising 2.8% of all newly diagnosed neoplasms. Diffuse gliomas are the most prevalent and the most aggressive primary brain tumors in adults. The incidence of diffuse gliomas varies among different populations; this variation is partially linked to genetic polymorphisms. The purpose of the study is to examine the association between (BRCA1 rs799917G>A, rs1799966T>C, EXO1 rs1047840G>A, EME1 rs12450550T>C, ERCC2 rs13181T>G, rs1799793C>T, and XRCC1 rs1799782G>A) DNA repair gene polymorphisms and glioblastoma multiforme (GBM) susceptibility, and survival in the Jordanian Arab population.

Methods

Eighty-four patients diagnosed with glioblastoma multiforme at the King Abdullah University Hospital (KAUH) between 2013 and 2018 and 225 healthy cancer-free control subjects with similar geographic and ethnic backgrounds to the patients were included in the study. Genomic DNA was extracted from the formalin-fixed paraffin-embedded tissues of the subjects. The Sequenom MassARRAY^® sequencer system (iPLEX GOLD) was used. The analyses included assessments of population variability and survival.

Results

This study is the first to address the relationship between BRCA1 rs1799966 and rs799917 SNP, and the risk of GBM among the Arab Jordanian population. The findings of the study show that BRCA1 rs799917 is associated with decreased risk of GBM in the recessive model (AA vs G/G-A/G: OR, 0.46, 95% CI, 0.26-0.82, p=0.01) and the same SNP is associated with increased risk of GBM in the overdominant model (AG vs G/G-A/A: OR, 1.72, 95% CI, 1.02-2.89, p=0.04).

Glutathione S-transferases genes variants and chemotherapy efficacy in gastrointestinal cancer patients: a meta-analysis based on 50 pharmacogenetic studies

Background: The role of glutathione s-transferase genes (GSTP1, GSTM1 and GSTT1) variants and the GSTP1 expression level on chemotherapy efficacy of gastrointestinal cancer (GIC) patients were inconsistent. Methods: A meta-analysis about GSTP1, GSTM1 and GSTT1 variants and the GSTP1 expression level on chemotherapy efficacy of GIC patients was performed using data from PubMed, PMC, EMBASE, Web of Science, and Wanfang database. Results: Our meta-analysis enrolled 50 publications including 6518 patients. We found that patients with GIC harboring GSTP1 (IIe105Val) Val locus had higher objective response rates (ORR) than the IIe/IIe genotypic patients (odds ratio (OR) = 1.580, 95% confidence interval (CI) = 1.159-2.154, P = 0.004). Significant associations were found between the Ile105Val variant and overall survival of Caucasian GIC patients (IIe/Val vs. IIe/IIe: OR = 0.797 (0.674-0.944), P = 0.009). Caucasian GIC patients and gastric cancer patients with GSTT1 null genotype had worse response rates compared to GSTT1 present patients (OR = 0.530 (0.356-0.789), P = 0.002; OR = 0.643 (0.463-0.895), P = 0.009, respectively). Conclusion: This meta-analysis illustrates that GSTP1 IIe105Val and GSTT1 null/present variants could be useful predictors of chemotherapy efficacy in patients with gastrointestinal cancer.

The effects of BRCA1 expression on the chemosensitivity of gastric cancer cells to platinum agents

Breast cancer type 1 susceptibility protein (BRCA1) is a tumor suppressor gene that encodes a nuclear phosphoprotein, which is involved in homologous recombination to repair DNA double strand breaks and maintain genome stability. When BRCA1 is mutated or altered, DNA damage may not be effectively repaired, which leads to DNA replication errors and cancer growth. Accordingly, people carrying a mutation in the BRCA1 gene possess an increased risk of several types of cancer, including breast and ovarian cancer. Previous clinical studies have reported an association between BRCA1 expression level and the incidence of gastric cancer; however, to the best of our knowledge, an in vitro study has not been performed to support these clinical observations. Therefore, the present study evaluated BRCA1 expression levels in gastric cancer cell lines. In addition, the IC₅₀ values of cisplatin and oxaliplatin in each cell line were determined to investigate a potential correlation between BRCA1 expression level and chemosensitivity to platinum agents. The present results revealed that the BRCA1 expression level in gastric cancer is variable and associated with the treatment response to platinum-based chemotherapy. This suggests that BRCA1 may serve as a therapeutic marker for platinum-based chemotherapy in gastric cancer.

Clinical significance of BRCA1 and BRCA2 mRNA and protein expression in patients with sporadic gastric cancer

The purpose of the present study was to investigate the clinical significance of BRCA1/BRCA2 DNA repair associated (BRCA1/BRCA2) gene expression in patients with sporadic gastric cancer (GC) who had received postoperative adjuvant chemotherapy. Breast cancer type 1 and 2 susceptibility protein (BRCA1 and BRCA2) expression and BRCA1/BRCA2 mRNA expression were evaluated using immunohistochemistry (IHC) and in-situ hybridization (ISH) on tissue GC microarray tissues, in addition to reverse transcription-quantitative polymerase chain reaction (RT-qPCR). The results were analyzed for clinicopathological associations. A total of 367 cases of sporadic GC (stages II and III) were subjected to BRCA1 and BRCA2 expression analysis, and for BRCA1 and BRCA2 IHC, 360 cases were informative. A total of 61 cases (16.9%) displayed a loss of BRCA1 and 63 (17.5%) displayed a loss of BRCA2. BRCA1 and BRCA2 ISH results were obtained in 364 cases, of which 98 (26.9%) presented with low expression of BRCA1 mRNA and 148 (40.7%) with low expression of BRCA2 mRNA. In 72 of the 367 cases, BRCA1 and BRCA2 mRNA expression levels were assessed using RT-qPCR, of which 50 (69.4%) and 56 (77.8%) displayed low expression of BRCA1 and BRCA2, respectively. Positive IHC expression of BRCA2 was associated with advanced tumor stage; however, BRCA1 expression was not associated with any clinicopathological parameters. Associations between the RT-qPCR and ISH methods were not significant for either BRCA1 or BRCA2. The results of Kaplan-Meier survival analysis with stage subgrouping revealed no significant differences with regard to survival rate. Of the multivariate analyses, neither BRCA1 nor BRCA2 IHC results were independent prognostic factors. In summary, the present study indicated that BRCA1 and BRCA2, as assessed by IHC, may be used as clinicopathological biomarkers to evaluate the prognosis of sporadic GC.

Associations between genetic polymorphisms of membrane transporter genes and prognosis after chemotherapy: meta-analysis and finding from Seoul Breast Cancer Study (SEBCS)

Membrane transporters can be major determinants of the pharmacokinetic profiles of anticancer drugs. The associations between genetic variations of ATP-binding cassette (ABC) and solute carrier (SLC) genes and cancer survival were investigated through a meta-analysis and an association study in the Seoul Breast Cancer Study (SEBCS). Including the SEBCS, the meta-analysis was conducted among 38 studies of genetic variations of transporters on various cancer survivors. The population of SEBCS consisted of 1338 breast cancer patients who had been treated with adjuvant chemotherapy. A total of 7750 SNPs were selected from 453 ABC and/or SLC genes typed by an Affymetrix 6.0 chip. ABCB1 rs1045642 was associated with poor progression-free survival in a meta-analysis (HR = 1.33, 95% CI: 1.07-1.64). ABCB1, SLC8A1, and SLC12A8 were associated with breast cancer survival in SEBCS (P_gene < 0.05). ABCB1 rs1202172 was differentially associated with survival depending on the chemotherapy (P_interaction = 0.035). Our finding provides suggestive associations of membrane transporters on cancer survival.

Expression of BRCA1 and ERCC1 as predictive clinical outcome after radiochemotherapy in patients with locoregionally moderate-advanced nasopharyngeal carcinoma

In this study, we examined ERCC1 and BRCA1 expression and clinical outcome of 201 phase-III-IV nasopharyngeal carcinoma patients who were treated with cisplatin-based induced chemotherapy and concurrent radiochemotherapy. The chemotherapy response rate of BRCA1^– and BRCA1⁺ patients was 73.6% and 55.8%, respectively. In addition, the chemotherapy response rate of ERCC1^– and ERCC1⁺ patients was 76.9% and 56.6%, respectively. In patients’ tissues, ERCC1 expression associated with BRCA1 expression. The chemotherapy response rate of BRCA1^– and ERCC1^– patients was (82.1%) and higher than that of other groups (range 52.4-73.1%). The radiochemotherapy response rate of BRCA1^– and ERCC1^– patients was higher than that BRCA1⁺ and ERCC1⁺ patients. BRCA1^– and ERCC1^– patients showed higher 3-year overall survival, failure-free survival, locoregional failure-free survival and distant failure-free survival compared to BRCA1⁺ or ERCC1⁺ patients. Moreover, the 3-year overall survival, failure-free survival and distant failure-free survival of the BRCA1^– and ERCC1^– group were higher than that of other groups. TNM stage, ERCC1 expression and the correlation between BRCA1 and ERCC1 expression seemed significant overall survival factors. In conclusion, in nasopharyngeal carcinoma patients, ERCC1 and BRCA1 may be a predictor of response to platinum-based chemotherapy and concurrent radiochemotherapy.

Influence of the ABCB1 polymorphisms on the response to Taxane-containing chemotherapy: a systematic review and meta-analysis

PURPOSE

Multidrug resistance mediated by ABCB1 has been perceived to be one of the obstacles for cancer chemotherapy. This meta-analysis was performed to verify the effect of the ABCB1 rs1045642 and rs1128503 polymorphisms on the response to Taxane-containing chemotherapy.

METHODS

Pooled odds ratios (ORs) and corresponding 95% confidence intervals (CIs) were employed to evaluate the impact of these two ABCB1 polymorphisms. R scripts were developed to perform the meta-analysis.

RESULTS

A total of nine articles (including nine studies for rs1045642 and five for rs1128503) were collected in our systematic review. However, our meta-analysis showed no significant effect of these two ABCB1 polymorphisms on the response to Taxane-containing regimens.

CONCLUSIONS

This study highlights the unsuitability of relying on the ABCB1 rs1045642 and rs1128503 polymorphisms as therapeutic response biomarkers of Taxane-containing chemotherapy. Further polycentric studies in larger and multiracial populations are needed to validate the conclusions.

Polymorphisms and mutations in GSTP1, RAD51, XRCC1 and XRCC3 genes in breast cancer patients

BACKGROUND

Genotoxic factors, including ionizing radiation and oxidative stress, are associated with genomic instability and development of breast cancer (BC). The homologous recombination DNA repair (HRR) pathway, base excision repair (BER) mechanism, and antioxidative enzymes are required as defense mechanisms against these DNA damaging agents. GSTP1, XRCC1, XRCC3 and RAD51 proteins are essential components of antioxidation, BER and HRR of DNA, respectively. Deficiencies in BER, HRR and antioxidation pathways are involved in the progression of cancer.

METHODS

Genomic DNA was extracted from formalin-fixed, paraffin-embedded tissue and blood samples of BC patients of an Italian population. Genomic DNA was also extracted from blood specimens of a control group. DNA sequencing was performed for six single-nucleotide polymorphisms (SNPs) in the GSTP1, RAD51, XRCC1 and XRCC3 genes in BC patients and the control group.

RESULTS

Two variants in the 5'-UTR of the XRCC3 (rs1799794 A/G) and RAD51 (rs1801321) genes showed a significant association with susceptibility to BC (OR = 4.125; 95% CI 1.057-16.102; p = 0.03 and OR = 2.04; 95% CI 0.4925-8.449; p = 0.007, respectively). Additionally, we reported 2 mutations in intron 7 of the XRCC3 gene, CTdel (rs543072564) and A/G (rs369703243).

CONCLUSIONS

Our results underscored the existence of an association between XRCC3-5'-UTR-A/G (rs1799794) and RAD51-5'-UTR G172T (rs1801321) genotypes and BC risk in an Italian population. The presence of mutations in the intronic region of the XRCC3 gene highlights the importance of more sequence screening of DNA repair genes for possible genetic penetrance in BC.

Dysregulation of mRNA profile in cisplatin-resistant gastric cancer cell line SGC7901

AIM

To explore novel therapeutic target of cisplatin resistance in human gastric cancer.

METHODS

The sensitivity of SGC7901 cells and cisplatin-resistant SGC7901 cells (SGC7901/DDP) for cisplatin were detected by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) assay. High-quality total RNA which isolated from SGC7901/DDP cells and SGC7901 cells were used for mRNA microarray analysis. Results were analyzed bioinformatically to predict their roles in the development of cisplatin resistance and the expression of 13 dysregulated mRNAs we selected were validated by quantitative real-time polymerase chain reaction (qRT-PCR).

RESULTS

SGC7901/DDP cells highly resistant to cisplatin demonstrated by MTT assay. A total of 1308 mRNAs (578 upregulated and 730 downregulated) were differentially expressed (fold change ≥ 2 and P-value < 0.05) in the SGC7901/DDP cells compared with SGC7901 cells. The expression of mRNAs detected by qRT-PCR were consistent with the microarray results. Gene Ontology, Kyoto Encyclopedia of Genes and Genomes pathway and protein-protein interaction analysis demonstrated that the differentially expressed mRNAs were enriched in PI3K-Akt, Notch, MAPK, ErbB, Jak-STAT, NF-kappaB signaling pathways which may be involved in cisplatin resistance. Several genes such as PDE3B, VEGFC, IGFBP3, TLR4, HIPK2 and EGF may associated with drug resistance of gastric cancer cells to cisplatin.

CONCLUSION

Exploration of those altered mRNAs may provide more promising strategy in diagnosis and therapy for gastric cancer with cisplatin resistance.

Can GSTM1 and GSTT1 polymorphisms predict clinical outcomes of chemotherapy in gastric and colorectal cancers? A result based on the previous reports

Background

Gastric and colorectal cancers remain the major causes of cancer-related death. Although chemotherapy improves the prognosis of the patients with gastrointestinal cancers, some patients do not benefit from therapy and are exposed to the adverse effects. The polymorphisms in genes including GSTM1 and GSTT1 have been explored to predict therapeutic efficacy; however, the results were inconsistent and inconclusive.

Materials and methods

A systematic review and meta-analysis was performed by searching relevant studies about the association between the GSTM1 and GSTT1 polymorphisms and chemotherapy efficacy in gastrointestinal cancers in databases such as PubMed, EMBASE, Web of Science, Chinese National Knowledge Infrastructure, and Wanfang database up to January 10, 2016. Subgroup analyses were also performed according to ethnicity, cancer type, evaluation criteria, study type, chemotherapy type, and age.

Results

A total of 19 articles containing 3,217 cases were finally included. Overall analysis suggested that no significance was found between overall toxicity, neurotoxicity, neutropenia, gastrointestinal toxicity, tumor response, and progression-free survival, and the polymorphisms in GSTM1 and GSTT1, while GSTM1 polymorphism associated with overall survival (OS; hazard ratio =1.213, 95% confidence interval =1.060–1.388, P=0.005). Subgroup analyses suggested that neurotoxicity was associated with GSTM1 polymorphism in the Asian population, neutropenia was associated with GSTM1 polymorphism in palliative chemotherapy and older patients (mean age >60 years), and tumor response was associated with GSTT1 polymorphism in gastric cancer and responders defined by complete and partial responses. Meanwhile, GSTM1 was associated with OS in Caucasians, Asians, those with colorectal cancer, and patients with mean age <60 years. GSTT1 polymorphism was also associated with OS in Caucasians and patients with mean age >60 years.

Conclusion

The polymorphisms in GSTM1 and GSTT1 did not associate with the chemotherapy-related toxicity in gastrointestinal cancers, while GSTT1 polymorphism associated with OS, and further well-designed, larger-scale epidemiological studies are needed to validate our results.

XRCC1 Gene Polymorphism, Clinicopathological Characteristics and Stomach Cancer Survival in Thailand

BACKGROUND

Stomach cancer is one of leading causes of death worldwide. In Thailand, the incidence and mortality of stomach cancer are in the top ten for cancers. Effects of DNA repair gene X-ray repair cross complementary protein 1 (XRCC1) polymorphisms and clinicopathological characteristics on survival of stomach cancer in Thailand have not been previously reported. The aim of this study was to investigate the effects of XRCC1 gene and clinicopathological characteristics on survival of stomach cancer patients in Thailand.

MATERIALS AND METHODS

Data and blood samples were collected from 101 newly diagnosed stomach cancer cases pathologically confirmed and recruited during 2002 to 2006 and followed-up for vital status until 31 October 2012. Genotype analysis was performed using real-time PCR-HRM. The data were analyzed using the Kaplan-Meier method to yield cumulative survival curve, log-rank test to assess statistical difference of survival and Cox proportional hazard models to estimate adjusted hazard ratio.

RESULTS

The total followed-up times were 2,070 person-months, and the mortality rate was 4.3 per 100 person-months. The median survival time after diagnosis was 8.07 months. The cumulative 1-, 3-, 5-years survival rates were 40.4%, 15.2 % and 10.1 % respectively. After adjustment, tumour stage were associated with an increased risk of death (p= 0.036). The XRCC1 Gln339Arg, Arg/Arg homozygote was also associated with increased risk but statistically this was non-significant.

CONCLUSIONS

In addition to tumour stage, which is an important prognostic factor affecting to the survival of stomach cancer patients, the genetic variant Gln339Arg in XRCC1 may non-significantly contribute to risk of stomach cancer death among Thai people. Larger studies with different populations are need to verify ours findings.

Predictive biomarkers for targeted and cytotoxic agents in gastric cancer for personalized medicine

Gastric cancer (GC) is the fourth most common cancer and the second leading cause of cancer. The treatment of GC remains challenging as the outcomes achieved with surgery alone or adjuvant or neoadjuvant chemotherapy and radiotherapy are relatively poor. New treatment strategies are emerging and are being tested in solid tumors including GC. Over the past few years, the treatment of metastatic colorectal cancer (CRC) has made great advances, but strategies to manage GC have improved little. Multiple drug resistance is common in GC chemotherapy and targeted therapy; some patients appear to receive treatment that is suboptimal or even inefficacious. Unfortunately, there are few validated predictive biomarkers to guide the tailored treatment of GC. ToGA and AVAGAST are two phase III trials that tested the efficacy and safety of targeted agents in advanced gastric cancer (AGC), and results clearly indicated that patients need to be selected and that targeted agents are the best hope for better results. This review aims to provide an overview of potential predictive biomarkers for cytotoxic and targeted agents in GC.

Predictive value of GSTP1 Ile105Val polymorphism in clinical outcomes of chemotherapy in gastric and colorectal cancers: a systematic review and meta-analysis

PURPOSE

Gastric and colorectal cancers remain the major causes of cancer-related death with a bad prognosis. Up to now, platinum combined with fluoropyrimidines has been most commonly used in chemotherapy regimens of gastric and colorectal cancers. Recently, a series of studies have been conducted to investigate the associations of biomarkers, such as GSTP1 Ile105Val polymorphism, with the chemotherapy efficacy in gastric and colorectal cancers; however, the results were not consistent and inconclusive. Here, we performed a systematic review and meta-analysis to summarize the associations of GSTP1 Ile105Val polymorphism with the chemotherapy efficacy in gastric and colorectal cancers.

METHODS

A systematic review was conducted to search relevant studies in English databases (PubMed, ISI Web of Science, and EMBASE) up to November 30, 2015. The pooling ORs or HRs were used to assess the strength of the associations of GSTP1 Ile105Val polymorphism with clinical outcomes such as tumor response, toxicity, progression-free survival (PFS), and overall survival (OS).

RESULTS

Forty-one papers containing 8169 cases were finally included in the present meta-analysis study. Of which, 28 articles were performed in colorectal cancers, one in gastrointestinal carcinoma (gastric and colon cancer), 11 in gastric cancers, and one in colorectal and gastroesophageal cancers. After pooling all the eligible studies, we identified significant associations of GSTP1 Ile105Val polymorphism with chemotherapy-related tumor response (G vs. A: OR 1.697, 95 % CI 1.191-2.418; GG vs. AA: OR 2.804, 95 % CI 1.414-5.560; AG vs. AA: OR 1.540, 95 % CI 1.011-2.347; GG vs. AAAG: OR 2.139, 95 % CI 1.256-3.641), PFS (GG vs. AA, HR 0.640, 95 % CI 0.455-0.900; AGGG vs. AA: HR 0.718, 95 % CI 0.562-0.919), and OS (AG vs. AA: HR 0.857, 95 % CI 0.746-0.986; GG vs. AA: HR 0.679, 95 % CI 0.523-0.882; AGGG vs. AA: HR 0.663, 95 % CI 0.542-0.812) in gastric and colorectal cancers and no significant association was found between the polymorphism with toxicity.

CONCLUSIONS

GSTP1 Ile105Val polymorphism was associated with tumor response, PFS, and OS in gastric and colorectal cancers after chemotherapy.

Association of DNA repair and xenobiotic pathway gene polymorphisms with genetic susceptibility to gastric cancer patients in West Bengal, India

Gastric cancer is one of the most common malignancies in India. DNA repair gene or xenobiotic pathway gene polymorphisms have recently been shown to affect individual susceptibility to gastric cancer. Here, the possible interaction between common polymorphisms in X-ray repair cross complementing group I (XRCC1) gene and glutathione S-transferase (GST) genes (GSTM1, GSTT1 and GSTP1), smoking and alcohol consumption and overall survival in gastric cancer patients were evaluated. In this population-based case control study, 70 gastric cancer patients and 82 healthy controls were enrolled. The epidemiological data were collected by a standard questionnaire, and blood samples were collected from each individual. XRCC1 Arg194Trp, Arg280His and Arg399Gln polymorphisms were determined by polymerase chain reaction and direct DNA sequencing. GSTM1 and GSTT1 null polymorphisms and GSTP1 Ile105Val polymorphism were identified by multiplex polymerase chain reaction and restriction fragment length polymorphism (RFLP), respectively. The risk of gastric cancer was significantly elevated in individuals with XRCC1 Arg/Gln +Gln/Gln (p = 0.031; odds ratio = 2.32; 95 % confidence interval (CI) 1.07-5.06) and GSTP1 Val/Val genotype (p = 0.009; odds ratio = 8.64; 95 % CI 1.84-40.55). An elevated risk for GC was observed in smokers and alcohol consumers carrying GSTP1 Ile/Val +Val/Val genotype (p = 0.041; odds ratio = 3.71; 95 % CI 0.98-14.12; p = 0.002; odds ratio = 12.31; 95 % CI 1.71-88.59). These findings suggest that XRCC1 rs25487 and GSTP1 rs1695 can be considered as a risk factor associated with gastric cancer and might be used as a molecular marker for evaluating the susceptibility of the disease.

Hsp90: A New Player in DNA Repair?

Heat shock protein 90 (Hsp90) is an evolutionary conserved molecular chaperone that, together with Hsp70 and co-chaperones makes up the Hsp90 chaperone machinery, stabilizing and activating more than 200 proteins, involved in protein homeostasis (i.e., proteostasis), transcriptional regulation, chromatin remodeling, and DNA repair. Cells respond to DNA damage by activating complex DNA damage response (DDR) pathways that include: (i) cell cycle arrest; (ii) transcriptional and post-translational activation of a subset of genes, including those associated with DNA repair; and (iii) triggering of programmed cell death. The efficacy of the DDR pathways is influenced by the nuclear levels of DNA repair proteins, which are regulated by balancing between protein synthesis and degradation as well as by nuclear import and export. The inability to respond properly to either DNA damage or to DNA repair leads to genetic instability, which in turn may enhance the rate of cancer development. Multiple components of the DNA double strand breaks repair machinery, including BRCA1, BRCA2, CHK1, DNA-PKcs, FANCA, and the MRE11/RAD50/NBN complex, have been described to be client proteins of Hsp90, which acts as a regulator of the diverse DDR pathways. Inhibition of Hsp90 actions leads to the altered localization and stabilization of DDR proteins after DNA damage and may represent a cell-specific and tumor-selective radiosensibilizer. Here, the role of Hsp90-dependent molecular mechanisms involved in cancer onset and in the maintenance of the genome integrity is discussed and highlighted.

ERCC1 and CYP1B1 polymorphisms as predictors of response to neoadjuvant chemotherapy in estrogen positive breast tumors

Purpose

Neoadjuvant chemotherapy (NCT) using anthracyclines and taxanes is a standard treatment for locally advanced breast cancer. Efficacy of NCT is however variable among patients and predictive markers are expected to guide the selection of patients who will benefit from NCT. A promising approach stand with polymorphisms located in genes encoding drug transporters, drug metabolizing enzymes and target genes which can affect drug efficacy. Our study investigated the potential of 37 polymorphisms to predict response to NCT in breast cancer.

Methods

118 women with breast adenocarcinoma were treated with FEC100 and taxotere. Genotyping was performed on germline DNA using the BioMark platform (Fluidigm). Pathological complete response (pCR) according to Sataloff criteria was correlated to clinical characteristics and genotypes using univariate and multivariate analyses.

Results

25 patients (21.2%) reached complete pathologic response. pCR rate is increased in SBRIII (p = 0.009), ER negative (p = 0.005) and triple negative (p = 0.006) tumors. pCR rate is significantly increased for patients carrying at least one variant allele for BRCA1, ERCC1 or SLCO1B3, and for patients homozygous for CYP1B1. The combination of ERCC1 and CYP1B1 polymorphisms is a potential predictor of NCT response in breast cancer (pCR rate reached 50 vs 21.2% for unselected patients), and particularly in ER + breast cancer subtype where pCR rate reached 41.2 vs 13.5% for unselected patients.

Conclusions

This study is the first to report ERCC1, BRCA1 and SLCO1B3 as markers of response to NCT in breast cancer. ERCC1/CYP1B1 combination might be of particular interest to predict response to NCT in breast cancer and particularly to help NCT indication for ER+ breast tumors.

Electronic supplementary material

The online version of this article (doi:10.1186/s40064-015-1053-0) contains supplementary material, which is available to authorized users.

Resveratrol Enhances Etoposide-Induced Cytotoxicity through Down-Regulating ERK1/2 and AKT-Mediated X-ray Repair Cross-Complement Group 1 (XRCC1) Protein Expression in Human Non-Small-Cell Lung Cancer Cells

Etoposide (VP-16), a topoisomerase II inhibitor, is an effective anti-cancer drug used for the treatment of non-small-cell lung cancer (NSCLC). Resveratrol is a naturally occurring polyphenolic compound that has been proved to have anti-cancer activity. XRCC1 is an important scaffold protein involved in base excision repair that is regulated by ERK1/2 and AKT signals and plays an important role in the development of lung cancer. However, the role of ERK1/2 and AKT-mediated XRCC1 expression in etoposide treatment alone or combined with resveratrol-induced cytotoxicity in NSCLC cells has not been identified. In this study, etoposide treatment increased XRCC1 mRNA and protein expression through AKT and ERK1/2 activation in two NSCLC cells, H1703 and H1975. Knockdown of XRCC1 in NSCLC cells by transfection of XRCC1 siRNA or inactivation of ERK1/2 and AKT resulted in enhancing cytotoxicity and cell growth inhibition induced by etoposide. Resveratrol inhibited the expression of XRCC1 and enhanced the etoposide-induced cell death and anti-proliferation effect in NSCLC cells. Furthermore, transfection with constitutive active MKK1 or AKT vectors could rescue the XRCC1 protein level and also the cell survival suppressed by co-treatment with etoposide and resveratrol. These findings suggested that down-regulation of XRCC1 expression by resveratrol can enhance the chemosensitivity of etoposide in NSCLC cells.

XRCC1 and ERCC1 polymorphisms are related to susceptibility and survival of colorectal cancer in the Chinese population

Excision repair cross complementing group 1 (ERCC1) and X-ray repair cross-complementing groups 1 (XRCC1) are DNA repair enzymes. Polymorphisms in DNA repair genes may be important factors affecting cancer susceptibility, prognosis and therapy outcome. The purpose of this study was to investigate the correlation of ERCC1 and XRCC1 polymorphisms with colorectal cancer (CRC) risk, and explore the effect of polymorphisms on event-free, overall survival and oxaliplatin-based therapy in CRC patients. Genotyping was examined with the iMLDR technique. An unconditional logistic regression model was used to estimate the association of certain polymorphisms with CRC risk. The Kaplan-Meier method, log-rank test and Cox regression model were employed to evaluate the effects of polymorphisms on survival analysis. Results showed that Trp/Trp genotype of XRCC1 Arg194Trp and AA genotype of ERCC1 rs2336219 have a significantly increased risk of CRC; Trp allele of XRCC1 Arg194Trp and CC genotype of ERCC1 rs735482 were associated with lower response to oxaliplatin-based chemotherapy, a shorter survival and a higher risk of relapse or metastasis. 194Trp/280Arg/399Arg haplotype was associated with a significant resistance, and the ERCC1 protein expression was statistically higher in tumours with rs735482 CC genotype than with AA genotype. Our studies indicate that XRCC1 and ERCC1 polymorphisms probably affect susceptibility, chemotherapy response and survival of CRC patients.

BRCA1 haplotype and clinical benefit of trabectedin in soft-tissue sarcoma patients

Background:

This study aimed to determine whether the BRCA1 haplotype was associated with trabectedin efficacy in soft-tissue sarcoma (STS) patients.

Methods:

We analysed BRCA1 single-nucleotide polymorphisms (SNPs) in tumour specimens from 135 advanced STS patients enrolled in published phase 2 trials or in a compassionate-use programme of trabectedin. Forty-four advanced STS patients treated with doxorubicin and 85 patients with localised STS served as controls. The 6-month nonprogression rate and overall survival (OS) were analysed according to BRCA1 haplotype using log-rank tests.

Results:

A favourable BRCA1 haplotype (presence of at least one AAAG allele) was significantly associated with an improved 6-month nonprogression rate. It was the only variable significantly associated with OS. No correlations were found between outcomes for patients with localised or advanced STS treated with doxorubicin.

Conclusions:

The BRCA1 haplotype represents a potential DNA repair biomarker that can be used for the prediction of response to trabectedin in STS patients.

Can pharmacogenetics explain efficacy and safety of cisplatin pharmacotherapy?

Several recent pharmacogenetic studies have investigated the variability in both outcome and toxicity in cisplatin-based therapies. These studies have focused on the genetic variability of therapeutic targets that could affect cisplatin response and toxicity in diverse type of cancer including lung, gastric, ovarian, testicular, and esophageal cancer. In this review, we seek to update the reader in this area of investigation, focusing primarily on DNA reparation enzymes and cisplatin metabolism through Glutathione S-Transferases (GSTs). Current evidence indicates a potential application of pharmacogenetics in therapeutic schemes in which cisplatin is the cornerstone of these treatments. Therefore, a collaborative effort is required to study these molecular characteristics in order to generate a genetic panel with clinical utility.

Role of the functional variant (-652T>G) in the XRCC4 promoter in prostate cancer

Several genes encoding DNA repair molecules have been proposed as cancer-susceptibility genes. Many studies have suggested that SNPs in XRCC4 could be implicated in altering the risk of prostate cancer (PCa). We examined the role of the functional variant (-652T>G) in the XRCC4 promoter in PCa. The transcriptional activity of XRCC4 gene was measured by luciferase assay. We performed real-time PCR/immunohistochemical assay to verify the association between expression level of XRCC4 mRNA/protein and XRCC4 -652T>G polymorphism. In addition, electrophoretic mobility shift assay (EMSA) was used to confirm whether this polymorphism has an effect on binding ability of the transcription factor. We found that the G variant significantly increased the transcription activity of the XRCC4 gene and the binding ability of transcriptional factor GATA-1 to the XRCC4 promoter. Furthermore, the results suggested that the XRCC4 protein and mRNA were overexpressed in individuals who carried the -652G allele compared to carriers of the -652T allele. In addition, the expression of XRCC4 in PCa tissues was lower than in adjacent normal tissues. Our data suggest that the XRCC4 promoter -652G>T polymorphism is functional and may influence genetic susceptibility to prostate cancer. Case-control studies are required to validate our findings in the future.

APE1 polymorphisms are associated with colorectal cancer susceptibility in Chinese Hans

AIM: To study the association between four base excision repair gene polymorphisms and colorectal cancer risk in a Chinese population.

METHODS: Two hundred forty-seven colorectal cancer (CRC) patients and three hundred cancer-free controls were enrolled in this study. Four polymorphisms (OGG1 Ser326Cys, APE1 Asp148Glu, -141T/G in the promoter region, and XRCC1 Arg399Gln) in components of the base excision repair pathway were determined in patient blood samples using polymerase chain reaction with confronting two-pair primers. The baseline information included age, gender, family history of cancer, and three behavioral factors [smoking status, alcohol consumption, and body mass index (BMI)]. χ² tests were used to assess the Hardy-Weinberg equilibrium, the distributions of baseline characteristics, and the four gene polymorphisms between the cases and controls. Multivariate logistic regression analyses were conducted to analyze the correlations between the four polymorphisms and CRC risk, adjusted by the baseline characteristics. Likelihood ratio tests were performed to analyze the gene-behavior interactions of smoking status, alcohol consumption, and BMI on polymorphisms and CRC susceptibility.

RESULTS: The APE1 148 Glu/Glu genotype was significantly associated with an increased risk of colorectal cancer (OR = 2.411, 95%CI: 1.497-3.886, P < 0.001 relative to Asp/Asp genotype). There were no associations between OGG1, XRCC1, or APE1 promoter polymorphisms and CRC risk. A multivariate analysis including three behavioral factors showed that the APE1 148 Glu/Glu genotype was associated with an increased risk for CRC among both smokers and non-smokers, non-drinkers and individuals with a BMI ≥ 25 kg/m² (ORs = 2.356, 3.299, 2.654, and 2.581, respectively). The XRCC1 399 Arg/Gln genotype was associated with a decreased risk of CRC among smokers and drinkers (OR = 0.289, 95%CI: 0.152-0.548, P < 0.001, and OR = 0.327, 95%CI: 0.158-0.673, P < 0.05, respectively). The APE1 promoter polymorphism -141 T/G genotype was associated with a reduced risk of colorectal cancer among subjects with a BMI < 25 kg/m² (OR = 0.214, 95%CI: 0.069-0.660, P < 0.05 relative to T/T genotype). There were significant gene-behavior interactions between smoking status and XRCC1 Arg399Gln, as well as BMI and APE1 -141T/G polymorphism (all P < 0.05).

CONCLUSION: APE1 Asp148Glu is associated with increased CRC risk and smoking alters the association between XRCC1 Arg399Gln and CRC risk in the Chinese Han population.

X-ray repair cross-complementing 1 polymorphism and prognosis of platinum-based chemotherapy in gastric and colorectal cancer: a meta-analysis

BACKGROUND AND AIM

The relationships between the X-ray repair cross-complementing 1 (XRCC1) Arg399Gln polymorphism (rs25487, G > A) and responses to platinum-based chemotherapy of gastric and colorectal cancer patients are controversial. Therefore, we performed a meta-analysis to assess the relationships.

METHODS

We retrieved the relevant articles from MEDLINE and EMBASE databases. Fourteen studies with 1618 gastric and colorectal cancer patients were included. Primary outcomes included response rate (RR), progression-free survival (PFS), and overall survival (OS). Odds ratio (OR) or hazard ratio with 95% confidence interval (CI) were estimated. All analyses were performed using the Stata software version 11.0 and Review Manager (v5.0).

RESULTS

In the dominant model, the A allele of XRCC1 Arg399Gln polymorphism was associated with reduced RR to platinum-based chemotherapy in all gastric and colorectal cancer patients (A/G + A/A vs G/G OR, 0.73; 95% CI, 0.55-0.96) and in Asians (OR, 0.62; 95% CI, 0.44-0.89) but not in Caucasians (OR, 0.92; 95% CI, 0.60-1.42). In addition, stratified analysis for different types of cancers indicated a marginally significant decrease of RR in colorectal cancer patients (OR, 0.68; 95% CI, 0.46-1.00) but not in gastric cancer patients (OR, 0.78; 95% CI, 0.53-1.15). However, we did not observe a significant association between XRCC1 Arg399Gln polymorphism and hazard for PFS and OS for gastric and colorectal cancer patients in all tested models.

CONCLUSIONS

XRCC1 Arg399Gln polymorphism may be a valuable genetic marker for platinum-based chemotherapy of gastric and colorectal cancer patients, and more well-designed studies with large samples are needed to confirm our findings.

Gastric cancer pharmacogenetics: progress or old tripe?

Gastric cancer remains the second most frequent cause of cancer-related mortality. While surgery is traditionally the initial treatment for early-stage disease, the addition of chemotherapy has been shown to significantly increase overall survival and progression-free survival in advanced and metastatic stages of disease. However, despite the incorporation of newer chemotherapies and regimens into gastric cancer clinical trials, the response rate and median overall survival for treated patients has not significantly improved throughout the years; therefore, newer therapeutic approaches to improve upon the medication selection process are warranted. Treatment and dose selection based on patient factors, such as genetic variation, may provide a more rational and potentially more powerful means of personalizing chemotherapy. This review provides an update on the current status of pharmacogenetic studies regarding germline DNA mutations that may alter response to chemotherapeutic agents used to treat gastric cancer, including perspectives on clinical translation and future work.

Association between polymorphisms in XRCC1 gene and treatment outcomes of patients with advanced gastric cancer: a systematic review and meta-analysis

Background

Many reports have shown inconsistent results on the relationship between single nucleotide polymorphisms (SNPs) of X-ray repair cross complementing protein (XRCC1) gene and platinum-based chemotherapeutic efficacy. This meta-analysis aimed to summarize published data about the association between two SNPs of XRCC1 (Arg194Trp and Arg399Gln) and treatment outcomes of patients with advanced gastric cancer.

Methodology/Principal Findings

We retrieved the relevant articles from MEDLINE, Web of Knowledge, and the China National Knowledge Infrastructure (CNKI) databases. Studies were selected according to specific inclusion and exclusion criteria. Study quality was assessed according to the guidelines outlined by Hayden, et al. and PRISMA guidelines. We estimated the odds ratio (OR) for response rate versus no response after platinum-based chemotherapy. Progression-free survival (PFS) and overall survival (OS) were evaluated by pooled Cox proportional hazard ratios (HRs) and 95% confidence intervals (CIs). We found that none of the XRCC1 Arg194Trp and Arg399Gln polymorphisms was significantly associated with tumor response. Stratified analysis by ethnicity or sensitivity analysis also showed that XRCC1 SNPs were not related with chemotherapy response. Patients with minor variant A allele were likely to have poorer 2-year survival rate than those with G/G genotype. However, in the group of 5-year follow up, there was no significant association between the A allele and OS yet.

Conclusions/Significance

There is no evidence to support the use of XRCC1 Arg194Trp and Arg399Gln polymorphisms as prognostic predictors of TR and PFS in gastric patients treated with platinum-based chemotherapy. The relationship between minor variant A allele and OS requires further verification.

SULF2 methylation is associated with in vitro cisplatin sensitivity and clinical efficacy for gastric cancer patients treated with a modified FOLFOX regimen

OBJECTIVE

Biomarkers capable of discriminating the patients who are likely to respond to certain chemotherapeutic agents could improve the clinical efficiency. The sulfatases(SULFs) play a critical role in the pathogenesis of a variety of human cancers. Here, we focused our investigation on the prognostic and predictive impact of SULF2 methylation in gastric cancer.

METHODS

Promoter CpG island methylation of SULF2 was analyzed in 100 gastric cancer samples. The in vitro sensitivity to cisplatin, docetaxel, gemcitabine, irinotecan and pemetrexed were determined by histoculture drug response assay(HDRA). Additionally, 56 gastric cancer patients treated with a modified FOLFOX regimen(biweekly oxaliplatin plus 5-FU and folinic acid) were retrospectively analyzed to further evaluate the prognostic and predictive impact of SULF2 methylation in gastric cancer.

RESULTS

Methylated SULF2(SULF2M) was detected in 28 patients, while the remaining 72 patients showed unmethylated SULF2(SULF2U, methylation rate: 28%). Samples with SULF2U were more sensitive to cisplatin than those with SULF2M(inhibition rate: 48.80% vs. 38.15%, P = 0.02), while samples with SULF2M were more sensitive to irinotecan than SULF2U(inhibition rate: 53.61% vs. 40.92%, P = 0.01). There were no association between SULF2 methylation and in vitro sensitivity to docetaxel, gemcitabine and pemetrexed. SULF2 methylation was found to have a significant association with cisplatin efficacy(SULF2M: 57.14%, SULF2U: 80.56%, P = 0.02) and irinotecan efficacy(SULF2M: 89.29%, SULF2U: 62.50%, P = 0.01). Among the 56 patients receiving the modified FOLFOX regimen, a significant association was observed between survival and SULF2 methylation status(SULF2M: 309 days, 95% CI = 236 to 382 days; SULF2U: 481 days, 95% CI = 418 to 490 days; P = 0.02). Multivariate analysis revealed that SULF2 methylation was an independent prognostic factor of overall survival in gastric cancer patients treated with platinum-based chemotherapy.

CONCLUSION

SULF2 methylation is negatively associated with cisplatin sensitivity in vitro. SULF2 methylation may be a novel prognostic biomarker for gastric cancer patients treated with platinum-based chemotherapy.

Quantitative assessment of the associations between DNA repair gene XRCC3 Thr241Met polymorphism and gastric cancer

Gastric cancer is one of the most prevalent types of cancer in the world today. Recently, there is a large sample volume of published case-control studies on XRCC3 Thr241Met polymorphism with gastric cancer. This will have an important impact on published article by meta-analysis regarding XRCC3 Thr241Met polymorphism with gastric cancer. Therefore, it is necessary to update by meta-analysis to comprehensively investigate the relationship between DNA repair gene XRCC3 Thr241Met polymorphism and gastric cancer. To preciously examine the association between the XRCC3 Thr241Met polymorphism and gastric cancer, we undertook a meta-analysis of 12 case-control studies. The association between the XRCC3 Thr241Met polymorphism and gastric cancer risk was assessed by odds ratios together with their 95 % confidence intervals using a fixed-effects model or random-effects model. We found that the XRCC3 Thr241Met polymorphism was not associated with an increased gastric cancer risk. However, the XRCC3 Thr241Met polymorphism was associated with decreased gastric cancer risk in Asians. In addition, there is no evidence of association on XRCC3 Thr241Met polymorphism with response to chemotherapy and prognosis in gastric cancer. The XRCC3 Thr241Met polymorphism might influence gastric cancer risk in Asians.

Progress in research of the BRCA1 gene in gastric cancer

Chemotherapy occupies an important position in the treatment of gastric cancer. Platinum drugs are commonly chemotherapy drugs for gastric cancer; however, sensitivity to these drugs varies among different patients. The breast cancer susceptibility gene 1 (BRCA1) is a tumor suppressor gene that is associated with sensitivity to platinum drugs. At present, the research on the BRCA1 gene is mainly focused on breast cancer, and there have been fewer studies on gastric cancer. This paper will give an overview of the structure and function of the BRCA1 gene and the relationship between BRCA1 and gastric cancer.

Clinical significance of TS and BRCA1 protein overexpression in gastric cancer

AIM: To investigate the correlation between thymidylate synthase (TS) and breast cancer susceptibility gene-1 (BRCA1) expression and clinicopathological characteristics of gastric cancer.

METHODS: Two hundred and forty-six surgical specimens of gastric cancer collected from patients with complete clinical data who were treated at Fuzhou General Hospital of Nanjing Military Command between January 2011 and January 2012 were used in this study. The protein expression of TS and BRCA1 in these specimens was examined by immunohistochemistry. The correlation between TS and BRCA1 protein expression and clinicopathological characteristics of gastric cancer was analyzed.

RESULTS: The rates of TS and BRCA1 overexpression in gastric cancer were 39.02% (96/246) and 55.69% (137/246), respectively. There was no relationship between TS overexpression and sex, age, tumor site, histotype, differentiation, distant metastasis, depth of invasion, TNM stage and lymph node metastasis (all P > 0.05). BRCA1 protein overexpression was associated with depth of invasion (P < 0.01) and TNM stage (P < 0.05), but not with sex, age, tumor site, differentiation, lymph node metastasis or distant metastasis (all P > 0.05). The co-expression rate of TS and BRCA1 in gastric cancer was 26.02% (64/246). The overexpression of TS was negatively correlated with that of BRCA1 (P < 0.01, r = 0.2472).

CONCLUSION: There exists TS and BRCA1 overexpression in gastric cancer. The overexpression of BRCA1was associated with TNM stage and depth of invasion, which implies that BRCA1 overexpression may be related to invasion of gastric cancer. Detection of BRCA1 protein overexpression may be used to assess the malignant biological behavior and prognosis of gastric cancer and help choose chemotherapy drugs.

Differing effects of adjuvant chemotherapy according to BRCA1 nuclear expression in gastric cancer

BACKGROUND

We aimed to investigate the role of BRCA1 nuclear expression in sporadic gastric cancer; currently, the role remains unknown.

METHODS

Patients with gastric cancer who received curative operation with D2 dissection were enrolled in this study. Adjuvant chemotherapy was administered at the discretion of the physician. According to BRCA1 nuclear expression analysis by immunohistochemistry (IHC) on tissue microarrays using anti-BRCA1 antibody MS110, BRCA1 expression was classified as negative, low expression, and high expression.

RESULTS

Among 318 cases, 155 cases (48.7 %) were identified as BRCA1-negative by IHC and 96 cases (30.2 %) revealed BRCA1 low expression, 67 cases (21.0 %) showed BRCA1 high expression. The negative or reduced expression of BRCA1 was more frequent in more advanced-stage disease (p < 0.001) and was associated with perineural invasion (p = 0.032). Disease-free survival (DFS) was significantly decreased with reduced BRCA1 expression (p = 0.027). This tendency was also observed in overall survival (OS), although the difference was not significant. The poorer prognosis of BRCA1-negative tumors was overcome through adjuvant chemotherapy. The benefit of adjuvant chemotherapy for DFS and OS in stage III was enhanced only in BRCA1-negative tumors (p < 0.001, p < 0.001, respectively), but not in BRCA1-positive tumors (p = 0.236, p = 0.148, respectively).

CONCLUSION

The reduction of BRCA1 nuclear expression is associated with advanced stage and perineural invasion. Moreover, negative BRCA1 nuclear expression is a predictive marker regarding the benefit of adjuvant chemotherapy in sporadic gastric cancer; these novel findings are of great importance, and further, larger studies are warranted.

Association of XRCC1 gene polymorphisms with the survival and clinicopathological characteristics of gastric cancer

Polymorphisms of the DNA repair gene X-ray repair cross-complementing protein 1 (XRCC1) Arg194Trp, Arg280His, and Arg399Gln have been shown to alter the DNA repair activity and to be associated with genetic susceptibility to several types of cancer. We indentified genotypes of 944 surgically resected gastric cancer (GC) patients by the SNaPshot method to investigate the association of these polymorphisms with clinical progression and outcomes of GC in a Chinese population. The XRCC1 codon 280 His carriers (Arg/His+His/His) held a significantly lower risk of distant metastasis in the dominant model (Pearson chi-square test P=0.019). A weak association of these cases with reduced risk of lymph node metastasis was also found (Pearson chi-square test P=0.051). Individuals carrying at least one Trp allele of XRCC1 codon 194 had an increased risk of death compared with those with Arg/Arg homozygotes in diffuse-type GC (adjusted hazard ratio=1.34, 95% confidence interval=1.05-1.71). Our findings demonstrated that the genetic variant Arg280His in XRCC1 may contribute to cancer progression and that XRCC1 Arg194Trp variants may act as a favorable prognostic indicator of resected GC, particularly among the diffuse-type GC. Larger studies are needed to verify our results in different populations.

BRCA1 mRNA expression as a predictive and prognostic marker in advanced esophageal squamous cell carcinoma treated with cisplatin- or docetaxel-based chemotherapy/chemoradiotherapy

BACKGROUND

The molecular backgrounds that determine therapeutic effectiveness in esophageal cancer remain largely unknown. Breast cancer susceptibility gene 1 (BRCA1) expression has been found to switch the response to cisplatin- or paclitaxel-based chemotherapy. It remains unclear how variations in BRCA1 expression influence clinical outcomes in esophageal cancer.

PATIENTS AND METHODS

Quantitative real-time polymerase chain reaction (qPCR) was performed to examine BRCA1 mRNA expressions in paraffin-embedded specimens from 144 patients with advanced or metastatic esophageal squamous cell carcinoma who received cisplatin- or docetaxel-based first-line treatments.

RESULTS

Low BRCA1 mRNA expression correlated with increased response rate (RR; P = 0.025 and 0.017, respectively) and median overall survival (mOS; P = 0.002 and P<0.001, respectively) in cisplatin-based chemotherapy or chemoradiotherapy group and also correlated with decreased RR (P = 0.017 and 0.024, respectively) and mOS (both P<0.001) in docetaxel-based chemotherapy or chemoradiotherapy group. Multivariate analysis revealed that low BRCA1 expression was an independent prognostic factor in cisplatin-based chemotherapy (HR 0.29; 95%CI 0.12-0.71; P = 0.007) or chemoradiotherapy (HR 0.12; 95%CI 0.04-0.37; P<0.001) group and higher risk for mortality in docetaxel-based chemotherapy (HR 5.02; 95%CI 2.05-12.28; P<0.001) or chemoradiotherapy (HR 7.02; 95%CI 2.37-27.77; P<0.001) group.

CONCLUSIONS

BRCA1 mRNA expression could be used as a predictive and prognostic marker in esophageal cancer who underwent first-line cisplatin- or docetaxel-based treatments.

Evidence for base excision repair processing of DNA interstrand crosslinks

Many bifunctional alkylating agents and anticancer drugs exert their cytotoxicity by producing cross links between the two complementary strands of DNA, termed interstrand crosslinks (ICLs). This blocks the strand separating processes during DNA replication and transcription, which can lead to cell cycle arrest and apoptosis. Cells use multiple DNA repair systems to eliminate the ICLs. Concerted action of repair proteins involved in Nucleotide Excision Repair and Homologous Recombination pathways are suggested to play a key role in the ICL repair. However, recent studies indicate a possible role for Base Excision Repair (BER) in mediating the cytotoxicity of ICL inducing agents in mammalian cells. Elucidating the mechanism of BER mediated modulation of ICL repair would help in understanding the recognition and removal of ICLs and aid in the development of potential therapeutic agents. In this review, the influence of BER proteins on ICL DNA repair and the possible mechanisms of action are discussed.

Polymorphisms in ERCC1, GSTs, TS and MTHFR predict clinical outcomes of gastric cancer patients treated with platinum/5-Fu-based chemotherapy: a systematic review

BACKGROUND

Despite genetic polymorphism in response to platinum/5-Fu chemotherapy in gastric cancer (GC) has been studied, data reported so far are conflicting and critical consideration is needed before translation to the treatment of GC.

METHODS

We performed a meta-analysis by using 20 eligible studies to examine polymorphisms of ERCC1, GSTs, TS and MTHFR in predicting clinical outcomes (response rate, overall survival and toxicity) of GC patients treated with platinum/5-Fu-based chemotherapy. The association was measured using random/fixed effect odds ratios (ORs) or hazard ratios (HRs) combined with their 95% confidence intervals (CIs) according to the studies' heterogeneity. Statistical analysis was performed with the software STATA 9.0 package.

RESULTS

No significant association was found between response rate and genetic polymorphism in TS, MTHFR, ERCC1, GSTM1 and GSTP1. However, response rate was higher in GSTT1 (+) genotype compared with GSTT1 (-) genotype (T-/T+: OR=0.67, 95% CI: 0.47-0.97). With regard to long term outcomes, we could observe a significant longer overall survival in TS 3R/3R [(2R2R+2R3R)/3R3R: HR=1.29, 95% CI: 1.02-1.64] and GSTP1 GG/GA [(GG+AG)/AA: HR=0.51, 95% CI: (0.39, 0.67)] genotypes. In addition, significant association was demonstrated between toxicity and genetic polymorphism in TS, MTHFR and GSTP1 in included studies.

CONCLUSION

Polymorphisms of ERCC1, GSTs, TS and MTHFR were closely associated with clinical outcomes of GC patients treated with platinum/5-Fu-based chemotherapy. Studies with large sample size using the method of multi-variant analyses may help us to give more persuasive data on the putative association in future.

Impact of DNA polymorphisms in key DNA base excision repair proteins on cancer risk

Genetic variation in DNA repair genes can modulate DNA repair capacity and may be related to cancer risk. However, study findings have been inconsistent. Inheritance of variant DNA repair genes is believed to influence individual susceptibility to the development of environmental cancer. Reliable knowledge on which the base excision repair (BER) sequence variants are associated with cancer risk would help elucidate the mechanism of cancer. Given that most of the previous studies had inadequate statistical power, we have conducted a systematic review on sequence variants in three important BER proteins. Here, we review published studies on the association between polymorphism in candidate BER genes and cancer risk. We focused on three key BER genes: 8-oxoguanine DNA glycosylase (OGG1), apurinic/apyrimidinic endonuclease (APE1/APEX1) and x-ray repair cross-complementing group 1 (XRCC1). These specific DNA repair genes were selected because of their critical role in maintaining genome integrity and, based on previous studies, suggesting that single-nucleotide polymorphisms (SNPs) in these genes have protective or deleterious effects on cancer risk. A total of 136 articles in the December 13, 2010 MEDLINE database (National Center for Biotechnology Information, http://www.ncbi.nlm.nih.gov/pubmed/) reporting polymorphism in OGG1, XRCC1 or APE1 genes were analyzed. Many of the reported SNPs had diverse association with specific human cancers. For example, there was a positive association between the OGG1 Ser326Cys variant and gastric and lung cancer, while the XRCC1 Arg399Gln variant was associated with reduced cancer risk. Gene-environment interactions have been noted and may be important for colorectal and lung cancer risk and possibly other human cancers.

Deep sequencing of gastric carcinoma reveals somatic mutations relevant to personalized medicine

BACKGROUND

Globally, gastric cancer is the second most common cause of cancer-related death, with the majority of the health burden borne by economically less-developed countries.

METHODS

Here, we report a genetic characterization of 50 gastric adenocarcinoma samples, using affymetrix SNP arrays and Illumina mRNA expression arrays as well as Illumina sequencing of the coding regions of 384 genes belonging to various pathways known to be altered in other cancers.

RESULTS

Genetic alterations were observed in the WNT, Hedgehog, cell cycle, DNA damage and epithelial-to-mesenchymal-transition pathways.

CONCLUSIONS

The data suggests targeted therapies approved or in clinical development for gastric carcinoma would be of benefit to ~22% of the patients studied. In addition, the novel mutations detected here, are likely to influence clinical response and suggest new targets for drug discovery.