Polymorphisms in the XRCC1 gene modify survival of bladder cancer patients treated with chemotherapy

The 8q24 region hosts miRNAs altered in biospecimens of colorectal and bladder cancer patients

BACKGROUND

The 8q24 locus is enriched in cancer-associated polymorphisms and, despite containing relatively few protein-coding genes, it hosts the MYC oncogene and other genetic elements connected to tumorigenesis, including microRNAs (miRNAs). Research on miRNAs may provide insights into the transcriptomic regulation of this multiple cancer-associated region.

MATERIAL AND METHODS

We profiled all miRNAs located in the 8q24 region in 120 colorectal cancer (CRC) patients and 80 controls. miRNA profiling was performed on cancer/non-malignant adjacent mucosa, stool, and plasma extracellular vesicles (EVs), and the results validated with The Cancer Genome Atlas (TCGA) data. To verify if the 8q24-annotated miRNAs altered in CRC were dysregulated in other cancers and biofluids, we evaluated their levels in bladder cancer (BC) cases from the TCGA dataset and in urine and plasma EVs from a set of BC cases and healthy controls.

RESULTS

Among the detected mature miRNAs in the region, 12 were altered between CRC and adjacent mucosa (adj. p < 0.05). Five and four miRNAs were confirmed as dysregulated in the CRC and BC TCGA dataset, respectively. A co-expression analysis of tumor/adjacent tissue data from the CRC group revealed a correlation between the dysregulated miRNAs and CRC-related genes (PVT1 and MYC) annotated in 8q24 region. miR-30d-5p and miR-151a-3p, altered in CRC tissue, were also dysregulated in stool of CRC patients and urine of BC cases, respectively. Functional enrichment of dysregulated miRNA target genes highlighted terms related to TP53-mediated cell cycle control.

CONCLUSIONS

Altered expression of 8q24-annotated miRNAs may be relevant for the initiation and/or progression of cancer.

Haplotypes of single cancer driver genes and their local ancestry in a highly admixed long-lived population of Northeast Brazil

Admixed populations have not been examined in detail in cancer genetic studies. Here, we inferred the local ancestry of cancer-associated single nucleotide polymorphisms (SNPs) and haplotypes of a highly admixed Brazilian population. SNP array was used to genotype 73 unrelated individuals aged 80-102 years. Local ancestry inference was performed by merging genotyped regions with phase three data from the 1000 Genomes Project Consortium using RFmix. The average ancestry tract length was 9.12-81.71 megabases. Strong linkage disequilibrium was detected in 48 haplotypes containing 35 SNPs in 10 cancer driver genes. All together, 19 risk and eight protective alleles were identified in 23 out of 48 haplotypes. Homozygous individuals were mainly of European ancestry, whereas heterozygotes had at least one Native American and one African ancestry tract. Native-American ancestry for homozygous individuals with risk alleles for HNF1B, CDH1, and BRCA1 was inferred for the first time. Results indicated that analysis of SNP polymorphism in the present admixed population has a high potential to identify new ancestry-associated alleles and haplotypes that modify cancer susceptibility differentially in distinct human populations. Future case-control studies with populations with a complex history of admixture could help elucidate ancestry-associated biological differences in cancer incidence and therapeutic outcomes.

Small Non-Coding RNA Profiling in Plasma Extracellular Vesicles of Bladder Cancer Patients by Next-Generation Sequencing: Expression Levels of miR-126-3p and piR-5936 Increase with Higher Histologic Grades

Bladder cancer (BC) is the tenth most frequent cancer worldwide. Due to the need for recurrent cystoscopies and the lack of non-invasive biomarkers, BC is associated with a high management burden. In this respect, small non-coding RNAs (sncRNAs) have been investigated in urine as possible biomarkers for BC, but in plasma their potential has not yet been defined. The expression levels of sncRNAs contained in plasma extracellular vesicles (EVs) from 47 men with BC and 46 healthy controls were assessed by next-generation sequencing. The sncRNA profiles were compared with urinary profiles from the same subjects. miR-4508 resulted downregulated in plasma EVs of muscle-invasive BC patients, compared to controls (adj-p = 0.04). In World Health Organization (WHO) grade 3 (G3) BC, miR-126-3p was upregulated both in plasma EVs and urine, when compared to controls (for both, adj-p < 0.05). Interestingly, two sncRNAs were associated with the risk class: miR-4508 with a downward trend going from controls to high risk BC, and piR-hsa-5936 with an upward trend (adj-p = 0.04 and adj-p = 0.05, respectively). Additionally, BC cases with low expression of miR-185-5p and miR-106a-5p or high expression of miR-10b-5p showed shorter survival (adj-p = 0.0013, adj-p = 0.039 and adj-p = 0.047, respectively). SncRNAs from plasma EVs could be diagnostic biomarkers for BC, especially in advanced grade.

Systematic Review: Genetic Associations for Prognostic Factors of Urinary Bladder Cancer

INTRODUCTION

Many germline associations have been reported for urinary bladder cancer (UBC) outcomes and prognostic characteristics. It is unclear whether there are overlapping genetic patterns for various prognostic endpoints. We aimed to review contemporary literature on genetic associations with UBC prognostic outcomes and to identify potential overlap in reported genes.

METHODS

EMBASE, MEDLINE, and PubMed databases were queried for relevant articles in English language without date restrictions. The initial search identified 1346 articles. After exclusions, 112 studies have been summarized. Cumulatively, 316 single-nucleotide polymorphisms (SNPs) were reported across prognostic outcomes (recurrence, progression, death) and characteristics (tumor stage, grade, size, age, risk group). There were considerable differences between studied outcomes in the context of genetic associations. The most commonly reported SNPs were located in OGG1, TP53, and MDM2. For outcomes with the highest number of reported associations (ie, recurrence and death), functional enrichment annotation yields different terms, potentially indicating separate biological mechanisms.

CONCLUSIONS

Our study suggests that all UBC prognostic outcomes may have different biological origins with limited overlap. Further validation of these observations is essential to target a phenotype that could best predict patient outcome and advance current management practices.

Effect of mitomycin C on X-ray repair cross complementing group 1 expression and consequent cytotoxicity regulation in human gastric cancer cells

Gastric cancer is the fourth most common cancer and ranks as the second leading cause of cancer-related deaths across the world. The combination therapy of surgery with chemotherapeutic drugs, that is, mitomycin C (MMC), is becoming a major strategy for patients with advanced gastric cancer. However, drug resistance is a major factor that limits the effectiveness of chemotherapy, which ultimately leads to the failure of cancer chemotherapy. X-ray repair cross complementing group 1 (XRCC1), a scaffold protein of the base excision repair process, has been implicated in the development of tumor chemoresistance. Thus, this study aimed to explore whether XRCC1 expression could be regulated, its role in gastric AGS cancer cells treated with MMC, and the underlying mechanism. The results of this study demonstrate that XRCC1 expression could be upregulated in AGS cells treated with MMC, and this upregulation could subsequently reduce the cytotoxicity of MMC in AGS cells. Furthermore, MMC-upregulated XRCC1 expression was regulated by MAPK signaling through activating the transcription factor Sp1. These results indicate the role of XRCC1 in the development of drug resistance to MMC in gastric AGS cells. Elucidating the mechanism concerning the MAPKs and transcription factor Sp1 may provide another notion for the development of a clinical chemotherapy strategy for gastric cancers in the future.

microRNA profiles in urine by next-generation sequencing can stratify bladder cancer subtypes

Bladder cancer (BC) is the most frequent malignancy of the urinary tract with a high incidence in men and smokers. Currently, there are no non-invasive markers useful for BC diagnosis and subtypes classification that could overcome invasive procedures such as cystoscopy. Dysregulated miRNA profiles have been associated with numerous cancers, including BC. Cell-free miRNAs are abundantly present in a variety of biofluids including urine and make them promising candidates in cancer biomarker discovery.

In the present study, the identification of miRNA fingerprints associated with different BC status was performed by next-generation sequencing on urine samples from 66 BC and 48 controls. Three signatures based on dysregulated miRNAs have been identified by regression models, assessing the power to discriminate different BC subtypes. Altered miRNAs according to invasiveness and grade were validated by qPCR on 112 cases and 65 controls (among which 46 cases and 16 controls were an independent group of subjects while the rest were replica samples).

The area under the curve (AUC) computed including three miRNAs (miR-30a-5p, let-7c-5p and miR-486-5p) altered in all BC subtypes showed a significantly increased accuracy in the discrimination of cases and controls (AUC model = 0.70; p-value = 0.01).

In conclusions, the non-invasive detection in urine of a selected number of miRNAs altered in different BC subtypes could lead to an accurate early diagnosis of cancer and stratification of patients.

Functional genetic variants of XRCC4 and ERCC1 predict survival of gastric cancer patients treated with chemotherapy by regulating the gene expression

DNA repair protects genomic integrity and may modulate chemotherapy efficacy. Few large-scale studies have evaluated predictive roles of genetic variants of DNA repair genes in survival of Chinese gastric cancer (GCa) patients treated with chemotherapy. Here, we assessed the roles of 35 single nucleotide polymorphisms (SNPs) in DNA repair genes in survival of 1002 GCa patients, of whom 694 received chemotherapy and 308 did not. Among patients receiving chemotherapy, the ERCC1 rs2298881A allele was associated with a better survival [hazards ratio (HR) = 0.82, 95% confidence interval (CI) = 0.69-0.98; P = 0.03], whereas two XRCC4 SNPs were associated with a worse survival (HR = 1.26, 95% CI = 1.03-1.54 for the rs10040363G allele, P = 0.02; and HR = 1.30, 95% CI = 1.06-1.59 for the rs2075685T allele, P = 0.01). These three SNPs were unique survival predictors for patients treated with chemotherapy (P < 0.05 for all) but not for patients without chemotherapy (P > 0.05 for all), suggesting that they modulated chemotherapy efficacy. Patients who received chemotherapy and had haplotypes with at least one death-risk allele in XRCC4 had a poor survival, and the trend for an increase in the number of death-risk alleles adversely affecting the survival was also observed in an allelic dose-dependent manner (P_trend  = 0.001). Further functional analysis revealed that the death-risk alleles up-regulated the gene expression, leading to a worse survival as suggested by our meta-analysis pooling both mRNA microarray data from the GEO database and published data (ERCC1: HR = 1.31 [1.08-1.58]; P = 0.006). These functional genetic variants may independently or jointly affect survival in chemotherapy-treated GCa patients by modulating the gene expression in the tumors.

Association between polymorphisms in DNA repair gene XRCC1 and non-melanoma skin cancer risk: a meta-analysis

Objective

Non-melanoma skin cancer (NMSC) is the most common malignancy with annually rising incidence. The aim of this study was to estimate the association between three coding polymorphisms (Arg399Gln, Arg194Trp, and Arg280His) of the DNA repair gene X-ray repair cross-complementing group 1 (XRCC1) and NMSC susceptibility.

Methods

Online databases were searched to retrieve case–control studies published between January 2000 and November 2016. Pooled odds ratio (OR) and 95% confidence interval (CI) were employed to assess the strength of association. Overall, 10 relevant studies were finally included for analysis, including 3,143 NMSC patients and 3,540 controls. For each polymorphism of XRCC1 gene, there were 3,050 cases and 3,463 controls for Arg399Gln, 914 cases and 1,182 controls for Arg194Trp, and 279 cases and 413 controls for Arg280His.

Results

Our results showed that these three polymorphisms in the XRCC1 coding region were not associated with increased risk of NMSC in the total studied population. However, subgroup analysis by ethnicities demonstrated that Gln/Arg genotype of Arg399Gln polymorphism was associated with increased risk of NMSC under the heterogeneous model in Asian populations (Gln/Arg vs Arg/Arg: OR =1.39, 95% CI =1.04–1.87, P=0.03); subgroup analysis by tumor types showed that Trp/Trp genotype of Arg194Trp was positively associated with decreased cancer risk in squamous-cell skin cancer (SCC) type under the homogeneous model (Trp/Trp vs Arg/Arg: OR =0.38, 95% CI =0.16–0.92, P=0.03).

Conclusion

Our results suggested that Arg399Gln variant of XRCC1 gene might be a risk factor for NMSC in Asian populations, and Arg194Trp variant of XRCC1 gene might be a protective factor for patients with SCC. In addition, future case–control studies are still needed to further evaluate the effect of XRCC1 polymorphisms in NMSC risk.

Polymorphism in XRCC1 gene modulates survival and clinical outcomes of advanced North Indian lung cancer patients treated with platinum-based doublet chemotherapy

Survival in lung cancer patients is genetically determined. Single nucleotide polymorphisms (SNPs) in DNA repair genes are observed to play a critical role in survival as DNA repair itself can behave as double-edged sword. We aim to explore the association of DNA repair gene XRCC1 in survival and clinical outcomes for North Indian population. Blood sample from patients diagnosed with lung cancer was taken. DNA isolation and genotyping were performed for the SNPs of XRCC1 gene. Further, patients were followed up through telephonic conversation after every 2 months for 3 years. Statistical analysis was carried out using Kaplan-Meier to determine the median survival time (MST) and Cox proportional regression model to determine the hazards ratio. Further, logistic regression was used to calculate to calculate the objective response. The mutant genotype for XRCC1 399 is observed to have a better survival (MST = 9.6). Histological stratification did not reveal any association for any SNP except for SCLC subtype in XRCC1 632 with an increased death rate (HR 3.08, p = 0.02). On stratification according to chemotherapy regimen administered; cisplatin/carboplatin + docetaxel was observed to increase survival for XRCC1 399 mutant genotype (AA) (HR 0.26, p = 0.05). Cisplatin/carboplatin + irinotecan increased survival in both heterozygotes (GA) and combined variants (GA + AA) (HR 0.22, p = 0.014; HR 0.23, p = 0.012). The polymorphic variants within the XRCC1 gene have found to play an important role in overall survival of lung cancer patients undergoing specific chemotherapy regimen.

Increased micronucleus frequency in peripheral blood lymphocytes predicts the risk of bladder cancer

Background:

Bladder cancer (BC) is among the most common malignancies worldwide. The identification of new biomarkers for early BC detection, recurrence/progression is urgently needed. The cytokinesis-block micronucleus assay (CBMN) evaluates chromosome damage in cultured human lymphocytes and micronuclei (MN) provide a convenient and reliable index of both chromosome breakage and loss.

Methods:

Chromosomal damage (expressed as frequencies of MN, nucleoplasmic bridges and nuclear buds (NBUD)) was evaluated by CBMN assay in cryopreserved lymphocytes from 158 age/smoking-matched pairs of cases and controls in relation to BC risk, recurrence or progression. Moreover, non-muscle invasive BC (NMIBC) patients were characterised for 783 DNA repair gene polymorphisms for their possible association with the investigated cytogenetic end points.

Results:

MN and NBUD frequencies were significantly higher in cases than in controls (P=0.001 and P=0.006, respectively), with the associations being stronger in NMIBC. In a logistic regression model, for each increase of one unit in the MN frequency, a 1.12 increased risk of developing NMIBC was observed. In NMIBC cases, 10 polymorphisms were associated with different MN frequencies after genotype stratification.

Conclusions:

A model including traditional BC risk factors, MN frequency and the selected polymorphisms differentially distributed in cases and controls improved BC patient identification. Understanding the meaning of systemic chromosomal damage in BC patients with respect to the general population may help to adopt specific prevention strategies and therapeutic intervention.

Differential expression of multidrug resistance‑related proteins in adriamycin‑resistant (pumc‑91/ADM) and parental (pumc‑91) human bladder cancer cell lines

Multidrug resistance (MDR) is the major obstacle to bladder cancer chemotherapy. Several mechanisms have been implicated in the development of MDR, including extrusion of the drug by cell membrane pumps, associated with P‑glycoprotein (P‑gp) and multidrug resistance‑associated protein (MRP); increased DNA damage repair, associated with topoisomerase II (Topo II); suppression of drug‑induced apoptosis, associated with p53; and regulation of cancer cell growth, associated with vascular endothelial growth factor (VEGF). In the present study, the expression levels of these five markers were detected in an adriamycin (ADM)‑resistant human bladder cancer cell line (pumc‑91/ADM) and its parental cell line (pumc‑91), in order to determine which marker is more important, or whether all of them participate in drug resistance. The expression levels of P‑gp, MRP, Topo II, VEGF and p53 were measured in the two cell lines by reverse transcription‑quantitative polymerase chain reaction, western blotting and immunohistochemistry. A significant increase in P‑gp, MRP and VEGF, and a decrease in Topo II mRNA expression were detected in the pumc‑91/ADM drug‑resistant cell line compared with the pumc‑91 cell line; however, no difference in p53 mRNA expression was detected between the cells. In pumc‑91/ADM cells, the protein expression levels of P‑gp and MRP were upregulated, whereas Topo II was significantly decreased. However, no marked differences in p53 or VEGF expression were detected between the two cell lines at the protein level. The cytoplasmic and cell membrane localization of P‑gp and MRP, the cytoplasmic localization of VEGF, and the nuclear localization of p53 and Topo II were confirmed in the two cell lines. The present study detected increased P‑gp and MRP, and reduced Topo II expression in pumc‑91/ADM cells compared with pumc‑91 cells; however, no difference was detected in p53 and VEGF expression between the cell lines. In conclusion, a significant upregulation of MRP and downregulation of Topo II were detected in the ADM‑resistant human bladder cancer cell line (pumc‑91/ADM) compared with in the parental cell line (pumc‑91).

Independent Replication of Published Germline Polymorphisms Associated with Urinary Bladder Cancer Prognosis and Treatment Response

BACKGROUND

Many studies investigated the prognostic or predictive relevance of single nucleotide polymorphisms (SNPs) in biologically plausible genes in urinary bladder cancer (UBC) patients. Most published SNP associations have never been replicated in independent patient series.

OBJECTIVE

To independently replicate all previously reported associations between germline SNPs and disease prognosis or treatment response in UBC.

METHODS

A Pubmed search was performed to identify studies published by July 1, 2014 reporting on germline SNP associations with UBC prognosis or treatment response. For the replication series, consisting of 1,284 non-muscle-invasive bladder cancer (NMIBC) and 275 muscle-invasive or metastatic bladder cancer (MIBC) patients recruited through the Netherlands Cancer Registry, detailed clinical data were retrieved from medical charts. Patients were genotyped using a genome-wide SNP array. SNP association with recurrence-free, progression-free, and overall survival (OS) within specific patient and treatment strata was tested using Cox regression analyses.

RESULTS

For only six of the 114 evaluated SNPs, the association with either UBC prognosis or treatment response was replicated at the p <  0.05 level: rs1799793 (ERCC2) and rs187238 (IL18) for BCG recurrence; rs6678136 (RGS4) and rs11585883 (RGS5) for NMIBC progression; rs12035879 (RGS5) and rs2075786 (TERT) for MIBC OS.

CONCLUSIONS

Non-replicated genetic associations in the literature require cautious interpretation. This single replication does not provide definitive proof of association for the six SNPs, and non-replication of other SNPs may result from population-specific effects or the retrospective patient enrollment.

H2AX phosphorylation level in peripheral blood mononuclear cells as an event-free survival predictor for bladder cancer

Bladder cancer (BC) has a typical aetiology characterized by a multistep carcinogenesis due to environmental exposures, genetic susceptibility, and their interaction. Several lines of evidence suggest that DNA repair plays a role in the development and progression of BC. In particular, the study of individual susceptibility to DNA double strand breaks (DSBs) may provide valuable information on BC risk, and help to identify those patients at high-risk of either recurrence or progression of the disease, possibly personalizing both surveillance and treatment. Among the different DSB markers, the most well characterized is phosphorylation of the histone H2AX (γ-H2AX). We assessed any potential role of γ-H2AX as a molecular biomarker in a case-control study (146 cases and 146 controls) to identify individuals with increased BC risk and at high-risk of disease recurrence or progression. We investigated γ-H2AX levels in peripheral blood mononuclear cells before and after their exposure to ionizing radiation (IR). We did not find any significant difference among cases and controls. However, we observed a significant association between γ-H2AX basal levels and risk of disease recurrence or progression. In particular, both BC patients as a whole and the subgroup of non-muscle invasive BC (NMIBC) with high basal H2AX phosphorylation levels had a decreased risk of recurrence or progression (for all BC HR 0.70, 95%CI 0.52-0.94, P = 0.02; for NMIBC HR 0.68, 95%CI 0.50-0.92, P = 0.01), suggesting a protective effect of basal DSB signaling. Our data suggest that γ-H2AX can be considered as a potential molecular biomarker to identify patients with a higher risk of BC recurrence. © 2015 Wiley Periodicals, Inc.

The Cellular Response to Oxidatively Induced DNA Damage and Polymorphism of Some DNA Repair Genes Associated with Clinicopathological Features of Bladder Cancer

Genome instability and impaired DNA repair are hallmarks of carcinogenesis. The study was aimed at evaluating the DNA damage response in H2O2-treated lymphocytes using the alkaline comet assay in bladder cancer (BC) patients as compared to clinically healthy controls, elderly persons, and individuals with chronic inflammations. Polymorphism in DNA repair genes involved in nucleotide excision repair (NER) and base excision repair (BER) was studied using the PCR-RFLP method in the Belarusian population to elucidate the possible association of their variations with both bladder cancer risk and clinicopathological features of tumors. The increased level of H2O2-induced DNA damage and a higher proportion of individuals sensitive to oxidative stress were found among BC patients as compared to other groups under study. Heterozygosity in the XPD gene (codon 751) increased cancer risk: OR (95% CI) = 1.36 (1.03-1.81), p = 0.031. The frequency of the XPD 312Asn allele was significantly higher in T ≥ 2 high grade than in T ≥ 2 low grade tumors (p = 0.036); the ERCC6 1097Val/Val genotype was strongly associated with muscle-invasive tumors. Combinations of homozygous wild type alleles occurred with the increased frequency in patients with non-muscle-invasive tumors suggesting that the maintenance of normal DNA repair activity may prevent cancer progression.

MicroRNA expression profiling in bladder cancer: the challenge of next-generation sequencing in tissues and biofluids

Bladder cancer (BC) is a heterogeneous disease characterized by a high recurrence rate that necessitates continuous cystoscopic surveillance. MicroRNAs (miRNAs) are detectable in tissues and biofluids such as plasma/serum and urine. They represent promising biomarkers with potential not only for detecting BC but also informing on prognosis and monitoring treatment response. In this review, the many aspects of the application of next-generation sequencing (NGS) to evaluate miRNA expression in BC is discussed, including technical issues as well as a comparison with results obtained by qRT-PCR. The available studies investigating miRNA profiling in BC by NGS are described, with particular attention to the potential applicability on biofluids. Altered miRNA levels have been observed in BC tissues by NGS, but these results so far only partially overlapped among studies and with previous data obtained by qRT-PCR. The discrepancies can be ascribed to the small groups of BC patients sequenced. The few available studies on biofluids are mainly focused on implementing RNA isolation and sequencing workflow. Using NGS to analyze miRNAs in biofluids can potentially provide results comparable to tissues with no invasive procedures for the patients. In particular, the analyses performed on exosomes/microvesicles appear to be more informative. Thanks to the improvement of both wet-lab procedures and pipelines/tools for data analyses, NGS studies on biofluids will be performed on a larger scale. MiRNAs detected in urine and serum/plasma will demonstrate their potentiality to describe the variegated scenario of BC and to become relevant clinical markers.

Immune therapies in non-muscle invasive bladder cancer

OPINION STATEMENT

Non-muscle invasive bladder cancer (NMIBC) continues to be a challenging disease to manage. Treatment involves transurethral resection and, often, intravesical therapy. Appropriate patient selection, accurate staging, and morphological characterization are vital in risk-stratifying patients to those who would most benefit from receiving intravesical therapy. Bacillus of Calmette and Guérin (BCG) continues to be the first-line agent of choice for patients with intermediate- and high-risk NMIBC. Treatment should begin with the standard induction course of 6 weekly treatments. The inclusion of subsequent maintenance courses of BCG is imperative to optimal therapeutic response. While patients with intermediate-risk disease should receive 1 year of maintenance therapy, high-risk patients benefit from up to 3 years of maintenance therapy. BCG use should not be used in low-risk patients with de novo Ta, low-grade, solitary, <3-cm tumors. Conversely, patients with muscle-invasive disease should forgo intravesical immunotherapy and proceed directly to radical cystectomy. Cystectomy also should be considered in patients with multiple T1 tumors, T1 tumors located in difficult to resect locations, residual T1 on re-resection, and T1 with concomitant CIS. Although promising new immunotherapeutic agents, such as Urocidin, protein-based vaccines, and immune check point inhibitors are undergoing preclinical and clinical investigation, immunotherapy in bladder cancer remains largely reliant on intravesical BCG with surgical consolidation as the standard salvage treatment for patients with BCG failure.

Genetic Variants in the Insulin-like Growth Factor Pathway and Colorectal Cancer Risk in the Netherlands Cohort Study

Interrelationships between insulin-like growth factors (IGFs), hyperinsulinaemia, diabetes, and colorectal cancer (CRC) indicate involvement of IGFs in colorectal tumorigenesis. We investigated the CRC risk associated with 24 single nucleotide polymorphisms (SNPs) in 9 genes related to the IGF pathway and an IGF1 19-CA repeat polymorphism. Variants were selected from literature and genotyped in toenail DNA from 3,768 subcohort members and 2,580 CRC cases from the Netherlands Cohort Study, which has a case-cohort design (n = 120,852). We used the follow-up period 1986–2002. Eighteen SNPs were unequivocally associated with selected endpoints in the literature and unfavorable alleles were aggregated into a genetic sum score. Cox regression showed that a higher genetic sum score significantly increased CRC risk at all subsites, except the rectum, in men (highest vs. lowest tertile: HR for CRC = 1.36, 95% CI: 1.11, 1.65; P-trend = 0.002). Single SNPs (except the IGF1 SNP rs5742694) were not associated with risk. Models including the total number of IGF1 19-CA repeats showed CRC risk was halved at all subsites in women carrying <38 repeats but not >38 repeats (≤36 versus 38 repeats: HR for CRC = 0.44; 95% CI: 0.33, 0.58; P-trend < 0.001). These findings support a role for variants in IGF-related genes in colorectal tumorigenesis.

Influences of ERCC1, ERCC2, XRCC1, GSTP1, GSTT1, and MTHFR polymorphisms on clinical outcomes in gastric cancer patients treated with EOF chemotherapy

This study investigated the associations between genetic polymorphisms of six genes involved in DNA repair, detoxification pathways, and fluoropyrimidine metabolism and clinical outcomes in MGC patients receiving EOF treatment. This retrospective study included 108 Chinese MGC patients receiving EOF as first-line chemotherapy. Nine single nucleotide polymorphisms (SNPs) of six genes (ERCC1 rs2298881, ERCC2 rs13181 and rs1799793, XRCC1 rs25487 and rs25489, GSTP1 rs1695, GSTT1 rs2266637, and MTHFR rs1801133 and rs1801131) were genotyped, and the associations between each SNP and clinical outcome were analyzed. XRCC1 rs25487 A allele was significantly associated with progression disease (PD) to EOF (p = 0.002), and patients with AA genotype had significantly poorer progression-free survival (PFS) (p = 0.001) and overall survival (OS) (p = 0.041) compared with patients with the G allele (GG + GA). ERCC2 rs13181 G allele was significantly associated with PD (p = 0.026), and G carriers (GG + GT) tended to have poorer PFS (p = 0.092) than TT homozygotes. ERCC2 rs1799793 GA genotype was associated with unfavorable PFS (p = 0.034) and a tendency toward poorer OS (p = 0.090) compared with GG homozygotes. Patients were categorized as either good (0 risk factors) or poor risk (≥1 unfavorable SNPs) using a prognostic index based on XRCC1 rs25487 AA, ERCC2 rs13181 (GG + GT), and ERCC2 rs1799793 GA genotypes, with median OS and PFS of 534 days, 281 days (p = 0.009) and 206 days, and 123 days (p < 0.001), respectively. These results suggest that the prognostic index comprising XRCC1 rs25487, ERCC2 rs13181, and rs1799793 polymorphisms may be a useful predictor of clinical outcomes in MGC treated with EOF.

Pharmacogenetic association between XRCC1 polymorphisms and improved outcomes in bladder cancer patients following intravesical instillation of epirubicin

BACKGROUND

XRCC1 is a multi-domain protein associated with bladder cancer. We investigated the relationship between the distribution of XRCC1 polymorphisms (rs915927 and rs2854501) and clinical outcomes following intravesical instillation with epirubicin (EPI) or mitomycin C (MMC).

METHODS

A TaqMan assay was performed to determine genotypes of 240 individuals diagnosed with bladder cancer. Logistic regression was used to assess the association between polymorphisms and relapse-free survival (RFS) of patients. Quantitative real-time polymerase chain reaction was performed to determine expression of XRCC1 polymorphisms. Survival curves were generated using the Kaplan-Meier method.

RESULTS

Risk of bladder cancer recurrence was significantly reduced in patients receiving EPI who had higher incidences of XRCC1 polymorphisms (P=0.009 for rs915927, P=0.001 for rs2854501). In participants administered MMC, results were not statistically significant.

CONCLUSIONS

Polymorphisms in XRCC1 SNP variants (rs915927 and rs2854501) were associated with improved clinical outcomes following EPI treatment.

Effects of JWA, XRCC1 and BRCA1 mRNA expression on molecular staging for personalized therapy in patients with advanced esophageal squamous cell carcinoma

BACKGROUND

DNA damage repair genes JWA, XRCC1 and BRCA1 were associated with clinical outcomes and could convert the response to the cisplatin-based therapy in some carcinomas. The synergistic effects of JWA, XRCC1 and BRCA1 mRNA expression on personalized therapy remain unknown in advanced esophageal squamous cell carcinoma (ESCC).

METHODS

We employed quantitative real-time polymerase chain reaction (qPCR) to determine the expression of JWA, XRCC1 and BRCA1 mRNA in paraffin-embedded specimen from 172 patients with advanced ESCC who underwent the first-line cisplatin-or docetaxel-based treatments.

RESULTS

High JWA or XRCC1mRNA expression was correlated with longer median overall survival (mOS) in all the patients (both P<0.001) or in subgroups with different regimens (all P<0.05), but not correlated with response rate (RR, all P>0.05). Multivariate analysis revealed that high JWA (HR 0.22; 95% CI 0.13-0.37; P<0.001) or XRCC1 (HR 0.36; 95% CI 0.21-0.63; P<0.001) mRNA expression emerged as the independent prognostic factors for ESCC patients in this cohort. But no significant difference in prognostic efficacy was found between JWA plus XRCC1 and JWA alone through ROC analysis. Further subgroup analysis showed cisplatin-based treatments could improve mOS of patients with low JWA expression (P<0.05), especially in those with low BRCA1 expression simultaneously (P<0.001); while in patients with high JWA expression, high BRCA1 mRNA expression was correlated with increased mOS in docetaxel-based treatments (P=0.044).

CONCLUSION

JWA, XRCC1and BRCA1 mRNA expression could be used as predictive markers in molecular staging for personalized therapy in patients with advanced ESCC who received first-line cisplatin- or docetaxel-based treatments.

XRCC1 polymorphisms associated with survival among Chinese bladder cancer patients receiving epirubicin and mitomycin C

The association between DNA repair gene polymorphisms and bladder cancer risk has been widely studied. However, only few studies have examined the correlation between bladder cancer and instillation agent sensitivity. The aim of this study was to examine the association between polymorphisms of DNA repair genes, namely X-ray repair cross-complementing group I (XRCC1) rs2854509 and rs3213255, and bladder cancer recurrence risk. We recruited 244 patients (130 treated with epirubicin and 114 treated with mitomycin C). Genomic DNA was used to examine the XRCC1 rs2854509 and rs3213255 genotypes by Taqman PCR analysis. Combination analysis of XRCC1 rs2854509 and rs3213255 and examination of XRCC1 diplotypes were performed to reveal possible correlations. The rs2854509 CC and rs3213255 TT genotypes conferred shorter survival times than the rs2854509 AC/AA and rs3213255 CC/CT genotypes in patients treated with epirubicin, but not in those treated with mitomycin C (MMC) in adjusted models [hazard ratio (HR) = 0.23, 95 % confidence interval (CI) = 0.10-0.53 for rs2854509 AC + AA compared with CC; HR = 0.17, 95 % CI = 0.06-0.46 for rs3213255 CC + CT compared with TT]. Combination analysis showed significantly increased recurrence-free survival (RFS) among patients simultaneously carrying the rs2854509 AC/AA and rs3213255 CC/CT genotypes with an HR of 0.15 (95 % CI = 0.05-0.45) compared to those carrying other genotypes. Diplotype analysis demonstrated that the A-C/C-T diplotype is associated with a lower risk of recurrence compared with the common wild C-T/C-T diplotype (HR = 0.17, 95 % CI = 0.06-0.51). Our results suggest that the rs2854509 CC and rs3213255 TT genotypes confer higher sensitivity to epirubicin instillation. Moreover, the A-C/C-T diplotype presents significantly lower recurrence risk than other diplotypes.

Genetic variants in genes involved in mechanisms of chemoresistance to anticancer drugs

Refractoriness to the pharmacological treatment of cancer is dependent on the expression levels of genes involved in mechanisms of chemoresistance and on the existence of genetic variants that may affect their function. Thus, changes in genes encoding solute carriers may account for considerable inter-individual variability in drug uptake and the lack of sensitivity to the substrates of these transporters. Moreover, changes in proteins involved in drug export can affect their subcellular localization and transport ability and hence may also modify the bioavailability of antitumor agents. Regarding pro-drug activation or drug inactivation, genetic variants are responsible for changes in the activity of drug-metabolizing enzymes, which affect drug clearance and may determine the lack of response to anticancer chemotherapy. The presence of genetic variants may also decrease the sensitivity to pharmacological agents acting through molecular targets or signaling pathways. Recent investigations suggest that changes in genes involved in DNA repair may affect the response to platinum-based drugs. Since most anticancer agents activate cell death pathways, the evasion of apoptosis plays an important role in chemoresistance. Several genetic variants affecting death-receptor pathways, the mitochondrial pathway, downstream caspases and their natural modulators, and the p53 pathway, whose elements are mutated in more than half of tumors, and survival pathways, have been reported. The present review summarizes the available data regarding the role of genetic variants in the different mechanisms of chemoresistance and discusses their potential impact in clinical practice and in the development of tools to predict and overcome chemoresistance.