DNA repair gene expression level in peripheral blood and tumour tissue from non-small cell lung cancer and head and neck squamous cell cancer patients

Exploring homologous recombination repair and base excision repair pathway genes for possible diagnostic markers in hematologic malignancies

Hematologic malignancies (HMs) are a collection of malignant transformations, originating from the cells in the bone marrow and lymphoid organs. HMs comprise three main types; leukemia, lymphoma, and multiple myeloma. Globally, HMS accounts for approximately 10% of newly diagnosed cancer. DNA repair pathways defend the cells from recurrent DNA damage. Defective DNA repair mechanisms such as homologous recombination repair (HRR), nucleotide excision repair (NER), and base excision repair (BER) pathways may lead to genomic instability, which initiates HM progression and carcinogenesis. Expression deregulation of HRR, NER, and BER has been investigated in various malignancies. However, no studies have been reported to assess the differential expression of selected DNA repair genes combinedly in HMs. The present study was designed to assess the differential expression of HRR and BER pathway genes including RAD51, XRCC2, XRCC3, APEX1, FEN1, PARP1, and XRCC1 in blood cancer patients to highlight their significance as diagnostic/ prognostic marker in hematological malignancies. The study cohort comprised of 210 blood cancer patients along with an equal number of controls. For expression analysis, q-RT PCR was performed. DNA damage was measured in blood cancer patients and controls using the comet assay and LORD Q-assay. Data analysis showed significant downregulation of selected genes in blood cancer patients compared to healthy controls. To check the diagnostic value of selected genes, the Area under curve (AUC) was calculated and 0.879 AUC was observed for RAD51 (p < 0.0001) and 0.830 (p < 0.0001) for APEX1. Kaplan-Meier analysis showed that downregulation of RAD51 (p < 0.0001), XRCC3 (p < 0.02), and APEX1 (p < 0.0001) was found to be associated with a significant decrease in survival of blood cancer patients. Cox regression analysis showed that deregulation of RAD51 (p < 0.0001), XRCC2 (p < 0.02), XRCC3 (p < 0.003), and APEX1 (p < 0.00001) was found to be associated with the poor prognosis of blood cancer patients. Comet assay showed an increased number of comets in blood cancer patients compared to controls. These results are confirmed by performing the LORD q-assay and an increased frequency of lesions/Kb was observed in selected genes in cancer patients compared to controls. Our results showed significant downregulation of RAD51, XRCC2, XRCC3, APEX1, FEN1, PARP1, and XRCC1 genes with increased DNA damage in blood cancer patients. The findings of the current research suggested that deregulated expression of HRR and BER pathway genes can act as a diagnostic/prognostic marker in hematologic malignancies.

Xeroderma Pigmentosum Complementation Group C (XPC): Emerging Roles in Non-Dermatologic Malignancies

Xeroderma pigmentosum complementation group C (XPC) is a DNA damage recognition protein essential for initiation of global-genomic nucleotide excision repair (GG-NER). Humans carrying germline mutations in the XPC gene exhibit strong susceptibility to skin cancer due to defective removal via GG-NER of genotoxic, solar UV-induced dipyrimidine photoproducts. However, XPC is increasingly recognized as important for protection against non-dermatologic cancers, not only through its role in GG-NER, but also by participating in other DNA repair pathways, in the DNA damage response and in transcriptional regulation. Additionally, XPC expression levels and polymorphisms likely impact development and may serve as predictive and therapeutic biomarkers in a number of these non-dermatologic cancers. Here we review the existing literature, focusing on the role of XPC in non-dermatologic cancer development, progression, and treatment response, and highlight possible future applications of XPC as a prognostic and therapeutic biomarker.

Impact of ERCC1 gene polymorphisms on response to cisplatin based therapy in oral squamous cell carcinoma (OSCC) patients

Background and Objectives

Cisplatin is one of the major drugs that used in the treatment of oral cancer.Excision repair cross-complementation group 1 (ERCC1) is a key DNA repair gene in the nucleotide excision repair pathway which is activated in the repair of intra- and interstrand DNA crosslink caused by platinum-based treatment. The aim of this study was to investigate the association between polymorphisms in ERCC1 (C118T & C8092A) genes and the response to cisplatin-based chemotherapy.

Methods

ERCC1polymorphisms (C118T & C8092A) were studied using PCR-RFLP method from 150 OSCC patients as cases as well as 150 normal tissues from the same patients were collected as controls for this study. Results: Frequencies of ERCC1 C118C, C118T and T118T genotypes were 60%, 28% and 12% in OSCC patients and 78%, 19% and 3% in the controls, respectively. The C118T & T118T genotype had a 1.69 and 4.97 -folds increased risk for OSCC. Frequencies of ERCC1 C8092C, C8092A and A8092A were 78%, 18% and 4% in the OSCC patients and 89%, 10%, amd 1% in the controls, respectively. The C8092A genotype showed a 1.97-fold increased risk for OSCC.

Interpretation & Conclusions

In conclusion, this study highlights the DNA repair gene polymorphisms that might play a role in mediating susceptibility to oral squamous cell carcinoma and cisplatin therapy. Our data suggest that the ERCC1 C118T, T118T and ERCC1 C8092A genotypes are genetic risk factors for Oral squamous cell carcinoma and ERCC1 118 C/T and C8092A polymorphisms have significant influence on clinical outcome.

The DNA damage response network in the treatment of head and neck squamous cell carcinoma

BACKGROUND

We sought to determine whether DNA damage response (DDR)-related aberrations predict therapeutic benefit in cisplatin-treated head and neck squamous cell carcinoma (HNSCC) patients and how DDR pathways are modulated after treatment with olaparib alone or in combination with cisplatin or durvalumab.

PATIENTS AND METHODS

Oxidative stress, abasic sites and DDR-related parameters, including endogenous DNA damage, DNA repair mechanisms and apoptosis rates, were evaluated in HNSCC cell lines and peripheral blood mononuclear cells from 46 healthy controls (HC) and 70 HNSCC patients at baseline and following treatment with cisplatin-containing chemoradiation or nivolumab or enrolled in the OPHELIA phase II trial (NCT02882308; olaparib alone, olaparib plus cisplatin, olaparib plus durvalumab).

RESULTS

HNSCC patients at diagnosis exhibited deregulated DDR-related parameters and higher levels of oxidative stress and abasic sites compared with HC (all P < 0.05). Accordingly, nucleotide excision repair (NER; ERCC1, ERCC2/XPD, XPA, XPC) and base excision repair (APEX1, XRCC1) genes were downregulated in patients versus HC whereas double-strand breaks repair (MRE11A, RAD50, RAD51, XRCC2) and mismatch repair (MLH1, MSH2, MSH3) genes were overexpressed. Corresponding results were obtained in cell lines (all P < 0.001). Excellent correlations were observed between individual ex vivo and in vivo/therapeutic results, with cisplatin non-responders showing higher levels of endogenous DNA damage, augmented oxidative stress and abasic sites, increased NER capacities and reduced apoptosis than responders (all P < 0.05). Also, longer progression-free survival correlated with lower NER capacity (P = 0.037) and increased apoptosis (P = 0.029). Interestingly, treatment with olaparib-containing regimens results in the accumulation of cytotoxic DNA damage and exerts an extra antitumor effect by elevating oxidative stress (all P < 0.05). Nivolumab induced no significant changes in the DDR parameters examined.

CONCLUSIONS

Aberrations in DDR signals are implicated in the response to HNSCC chemotherapy and can be exploited as novel therapeutic targets, sensitive/effective non-invasive biomarkers as well as for the design of novel clinical trials.

Higher order genes interaction in DNA repair and cytokine genes polymorphism and risk to lung cancer in North Indians

Context

Lung cancer pathological process involves cumulative effects exerted by gene polymorphism(s), epigenetic modifications, and alterations in DNA repair machinery. Further, DNA damage due to oxidative stress, chronic inflammation, and the interplay between genetic and environmental factors is also an etiologic milieu of this malignant disease.

Aims

The present study aims to assess the prognostic value of DNA repair, cytokines, and GST gene polymorphism in lung cancer patients who had not received any neoadjuvant therapy.

Materials and Methods

In this case-control study, 127 cases and 120 controls were enrolled. DNA from the blood samples of both patients and controls was used to genotype XRCC1Arg399Gln, XPDLys751Gln, and interleukin-1 (IL-1β) genes by polymerase chain reaction (PCR)-restriction fragment length polymorphism method, whereas multiplex PCR was performed to genotype GSTT1 and GSTM1.

Results

Binary logistic regression analysis showed that XRCC1Arg399Gln-mutant genotype (Gln/Gln, odds ratio [OR] = 4.6, 95% confidence interval [CI]: 2.2-9.6) and GSTT1 null (OR = 2.7, 95% CI: 1.6-4.5) were linked to cancer susceptibility. Generalized multidimensional reduction analysis of higher order gene-gene interaction using cross-validation testing (CVT) accuracy showed that GSTT1 (CVT 0.62, P = 0.001), XPD751 and IL-1β (CVT 0.6, P = 0.001), and XRCC1399, XPD751, and interleukin-1 receptor antagonists (IL-1RN) (CVT 0.98, P = 0.001) were single-, two-, and three-factor best model predicted, respectively, for lung cancer risk. Classification and regression tree analysis results showed that terminal nodes which contain XRCC1399-mutant genotype (AA) had increased the risk to lung cancer.

Conclusion

The present study demonstrated that XRCC1399 (Gln/Gln), GSTT1, and IL-1RN allele I, I/II served as the risk genotypes. These genes could serve as the biomarkers to predict lung cancer risk.

ERCC1 C8092A polymorphism predicts fair survival outcome in Japanese patients with pharyngo-laryngeal squamous cell carcinoma

PURPOSE

To evaluate the prognostic significance of DNA excision repair gene polymorphisms, excision repair cross-complementation group 1 (ERCC1) and X-ray repair complementing defective repair in Chinese hamster cells 1 (XRCC1) polymorphisms were investigated in Japanese patients with head and neck squamous cell carcinoma (HNSCC).

METHODS

A total of 225 consecutive patients with HNSCC who underwent surgery or chemoradiotherapy/radiotherapy (CRT/RT) with curative intent as primary treatment from 2006 to 2017 were recruited. ERCC1 C8092A and XRCC1 Arg399Gln polymorphisms in DNA extracted from individual blood samples were determined by the polymerase chain reaction-restriction fragment length polymorphism method. Cumulative survival was estimated by Kaplan-Meier analysis with a log-rank test and Cox proportional hazards model stratified by treatment arm, adjusting for clinical prognostic factors.

RESULTS

Multivariate analysis showed that carriers with the ERCC1 8092 (C/A+A/A) genotype (hazard ratio, 3.56; 95% confidence interval, 1.22-7.39; p = 0.02) had significantly worse survival than those with ERCC1 8092 C/C who received CRT/RT. Conversely, the XRCC1 Arg399Gln polymorphism did not influence survival in patients who received CRT/RT as well as surgery.

CONCLUSION

The ERCC1 C8092A polymorphism might be an independent predictor of response to CRT and survival outcome in patients with HNSCC. This is the first report to investigate the role of DNA excision repair gene polymorphisms in patients with head and neck cancer in a Japanese population.

Validation of gene expression profiles of candidate genes using low density array in peripheral blood of tobacco consuming head and neck cancer patients and auto/taxi drivers with preneoplastic lesions

TaqMan Low-Density Array (TLDA) based Real-Time PCR (RT-PCR) of selected genes showed increased expression of polycyclic aromatic hydrocarbons (PAHs) metabolizing cytochrome P450s (CYPs), glutathione S-transferases (GSTs) and associated transcription factors in biopsy and peripheral blood samples isolated from head and neck squamous cell carcinoma (HNSCC) patients when compared to the controls. The genes involved in DNA repair, signal transduction pathway, EMT pathway, apoptosis, and cell adhesion/motility were found to be altered in both peripheral blood and biopsy samples of HNSCC patients. Transcription profiles in blood isolated from auto/taxi drivers, with pre-neoplastic lesions and history of tobacco use, also showed similar alterations. The present TLDA data thus demonstrates that low-density array of selected genes in peripheral blood has the potential to be used as a surrogate for providing insight into cancer progression pathways and possibly as an early biomarker for monitoring tobacco induced HNSCC.

Clinical research of individualized therapy in advanced esophageal cancer based on the ERCC1 C8092A genotype

The present study aimed to explore the role and clinical value of the detection of Excision repair cross-complementing 1(ERCC1) C8092A polymorphisms in individualized therapy of patients with advanced esophageal cancer. A total of 127 patients with advanced esophageal cancer were enrolled between January 2010 and January 2014 in Anhui Provincial Hospital. Patients were randomly assigned in a 1:2 ratio to a standard treatment group or an individualized treatment group, respectively, prior to ERCC1 C8092A assessment. Patients in the standard treatment group were treated with paclitaxel and cisplatin. The DNA was obtained from the peripheral blood of individualized treatment patients, amplified by PCR and sequenced to determine the ERCC1 C8092A polymorphism prior to the administration of chemotherapies. Patients with the ERCC1 C8092A genotype of A/A or A/C received paclitaxel and cisplatin, and those with the genotype of C/C received paclitaxel and fluorouracil. The primary endpoint was response rate (RR). The secondary endpoints included toxicity of chemotherapy, progression-free survival (PFS) and overall survival (OS) times. Differences between the groups were evaluated by χ² test. Differences in survival were analyzed by Kaplan-Meier survival curves. The survival rate was analyzed by log-rank test. Follow-up data was obtained until December 2015. The RR was obtained for 15 patients (34.8%) in the standard treatment group and 45 patients (53.6%) in the individualized treatment group (χ²=3.095; P=0.046). For adverse events, nausea and vomiting and anemia were significantly decreased in the individualized treatment group compared with the standard treatment group (P=0.001 and P=0.004, respectively). The median progression free survival time was 4.4 months [95% confidence interval (CI)3.8-5.0 months] in the standard treatment group and 6.6 months (95% CI, 5.8-7.4 months) in the individualized treatment group (P=0.018). The median overall survival time was 11.4 months (95% CI, 10.1-12.7 months) in the standard treatment group and 14.2 months (95% CI, 13.2-15.2 months) in the individualized treatment group (P=0.008). The RR, toxicity of chemotherapy, PFS and OS were significantly improved in the individualized treatment group compared with the standard treatment group. Detection of ERCC1 gene polymorphisms maybe performed for patients with advanced esophageal cancer to improve individualized therapy, which requires additional study.

Exploratory analysis of ERCC2 DNA methylation in survival among pediatric medulloblastoma patients

AIM

Medulloblastoma is the most frequent malignant pediatric brain tumor. While survival rates have improved due to multimodal treatment including cisplatin-based chemotherapy, there are few prognostic factors for adverse treatment outcomes. Notably, genes involved in the nucleotide excision repair pathway, including ERCC2, have been implicated in cisplatin sensitivity in other cancers. Therefore, this study evaluated the role of ERCC2 DNA methylation profiles on pediatric medulloblastoma survival.

METHODS

The study population included 71 medulloblastoma patients (age <18years at diagnosis) and recruited from Texas Children's Cancer Center between 2004 and 2009. DNA methylation profiles were generated from peripheral blood samples using the Illumina Infinium Human Methylation 450 Beadchip. Sixteen ERCC2-associated CpG sites were evaluated in this analysis. Multivariable regression models were used to determine the adjusted association between DNA methylation and survival. Cox regression and Kaplan-Meier curves were used to compare 5-year overall survival between hyper- and hypo-methylation at each CpG site.

RESULTS

In total, 12.7% (n=9) of the patient population died within five years of diagnosis. In our population, methylation of the cg02257300 probe (Hazard Ratio=9.33; 95% Confidence Interval: 1.17-74.64) was associated with death (log-rank p=0.01). This association remained suggestive after correcting for multiple comparisons (FDR p<0.2). No other ERCC2-associated CpG site was associated with survival in this population of pediatric medulloblastoma patients.

CONCLUSION

These findings provide the first evidence that DNA methylation within the promoter region of the ERCC2 gene may be associated with survival in pediatric medulloblastoma. If confirmed in future studies, this information may lead to improved risk stratification or promote the development of novel, targeted therapeutics.

Increased expression of ERCC2 gene in head and neck cancer is associated with aggressive tumors: a systematic review and case-control study

INTRODUCTION

The excision repair cross-complementation group 2 (ERCC2) ATP-dependent helicase is an essential member of the DNA repair pathway. It has been observed to be differentially expressed in different cancers, which shows its involvement in carcinogenesis.

AIM

In the present study we have tried to determine the association of expression patterns of this gene with head and neck carcinogenesis.

METHOD

We first carried out a systematic review of the available studies on the role of ERCC2 in head and neck cancer (HNC). In order to test the hypothesis that the expression patterns of XPD/ERCC2 play a critical role in HNC pathogenesis, we then conducted a population based case-control study on 81 head and neck tumor samples and adjacent normal-tissue control samples. Reverse transcriptase polymerase chain reaction (RT-PCR) and quantitative polymerase chain reaction (qPCR) were used to assess ERCC2 deregulation at the mRNA level.

RESULT

Expression analysis showed that the ERCC2 expression level was significantly upregulated (p<0.05) in HNC tissues compared with adjacent normal tissues. Furthermore, the expression pattern of ERCC2 was correlated with the expression pattern of Ki-67 and a significant correlation (r = 0.230, p<0.03) was observed between ERCC2 and Ki-67. Spearman's correlation also showed a significant correlation between ERCC2 expression and tumor stage (r = 0.271, p<0.02) and grade (r = 0.228, p<0.02) of HNC.

CONCLUSIONS

Our data suggest that deregulation of ERCC2 in HNC has the potential to predict a more aggressive cancer phenotype and may be considered a possible biomarker for improved diagnosis and prognosis of HNC.

XPC: Going where no DNA damage sensor has gone before

XPC has long been considered instrumental in DNA damage recognition during global genome nucleotide excision repair (GG-NER). While this recognition is crucial for organismal health and survival, as XPC's recognition of lesions stimulates global genomic repair, more recent lines of research have uncovered many new non-canonical pathways in which XPC plays a role, such as base excision repair (BER), chromatin remodeling, cell signaling, proteolytic degradation, and cellular viability. Since the first discovery of its yeast homolog, Rad4, the involvement of XPC in cellular regulation has expanded considerably. Indeed, our understanding appears to barely scratch the surface of the incredible potential influence of XPC on maintaining proper cellular function. Here, we first review the canonical role of XPC in lesion recognition and then explore the new world of XPC function.

The roles of excision repair cross-complementation group1 in objective response after cisplatin-based concurrent chemoradiotherapy and survival in head and neck cancers: a systematic review and meta-analysis

Our aim of the study was to investigate the precise relationship of repair cross-complementation group 1 (ERCC1) expression and the survival as well as objective response rate to cisplatin-based concurrent chemoradiotherapy (CCRT) and a meta-analysis was conducted to analysis ERCC1's prognostic roles in head and neck cancer. A search based on published articles in PubMed, Embase and CKNI database (up to Oct 15, 2014) to find eligible studies meeting eligibility criteria and then a meta-analysis was conducted to assess the outcomes in head and neck squamous cell carcinomas (HNSCC) patients with different ERCC1 expression. The principle outcomes were hazard ratio (HR) for survival analysis and relative risks (RR) for objective response. Fixed or random model was used for calculation according to the heterogeneity. The results showed that 9 studies involving 568 patients met the inclusion criteria. Low/negative expression of ERCC1 was associated with longer overall survival (OS) and profession-free survival (PFS) after receiving cisplatin-based CCRT therapy (HR 0.38; 95% confidence interval (CI) 0.21-0.63; P<0.001 and HR 0.37; 95%CI 0.21-0.63; P<0.001). And there was no significant difference discovered in objective response rate between low/negative and high/positive ERCC1 expression (RR 1.19; 95%CI 1.00-1.43; P=0.06). Evidence of modest heterogeneity was found between ERCC1 expression and OS (I(2)=48.8%, P<0.05) and subgroup analysis was performed based on ethnicity, variable methods and primary tumor location. The conclusion is that ERCC1 might be the one of adverse prognostic factors affecting the survival time and objective response to cisplatin-based chemoradiotherap due to its drug-resistance characteristics.

Association of the XPA A23G polymorphism with the risk of head and neck carcinomas: Evidence from 5,491 subjects

The XPA gene participates in modulating DNA damage recognition during the DNA nucleotide excision repair process. Current data regarding the association of the XPA A23G polymorphism with the risk of head and neck squamous cell carcinoma (HNSCC) remain controversial, and meta-analyses focusing on the HNSCC risk and this polymorphism are limited. Therefore, the aim of the present study was to derive a more precise estimation of this association by a meta-analysis of all the eligible studies. Odds ratios (ORs) with 95% confidence intervals (CI) were assessed for the strength of the associations in eight studies, including 5,491 subjects (2,409 HNSCC cases and 3,082 controls). The overall analysis revealed that the XPA A23G polymorphism was not significantly associated with the overall HNSCC risk. Consistently, there was no evidence for the association between the XPA A23G polymorphism and HNSCC risk in subgroup analyses based on ethnicity and the source of controls. However, the significant associations in oral carcinoma with the increased risk among the XPA heterozygote (AG vs. AA: OR, 1.58; 95% CI, 1.06-2.37; P_{heterogeneity}=0.23, I²=30%) and dominant (AG +GG vs. AA: OR, 1.53; 95% CI, 1.04-2.23; P_{heterogeneity}=0.21, I²=36%) models were observed in the subgroup analysis by tumor site. In conclusion, the meta-analysis suggested that the XPA A23G polymorphism was not associated with overall HNSCC susceptibility, but it was associated with oral carcinoma susceptibility and it may be a risk factor for oral carcinoma. Further well-designed and large studies are required to confirm these associations.

Significant accumulation of persistent organic pollutants and dysregulation in multiple DNA damage repair pathways in the electronic-waste-exposed populations

Electronic waste (e-waste) has created a worldwide environmental and health problem, by generating a diverse group of hazardous compounds such as persistent organic pollutants (POPs). Our previous studies demonstrated that populations from e-waste exposed region have a significantly higher level of chromosomal aberrancy and incidence of DNA damage. In this study, we further demonstrated that various POPs persisted at a significantly higher concentration in the exposed group than those in the unexposed group. The level of reactive oxygen species and micronucleus rate were also significantly elevated in the exposed group. RNA sequencing analysis revealed 31 genes in DNA damage responses and repair pathways that were differentially expressed between the two groups (Log2 ratio >1 or <-1). Our data demonstrated that both females and males of the exposed group have activated a series of DNA damage response genes; however many important DNA repair pathways have been dysregulated. Expressions of NEIL1/3 and RPA3, which are critical in initiating base pair and nucleotide excision repairs respectively, have been downregulated in both females and males of the exposed group. In contrast, expression of RNF8, an E3 ligase involved in an error prone non-homologous end joining repair for DNA double strand break, was upregulated in both genders of the exposed group. The other genes appeared to be differentially expressed only when the males or females of the two groups were compared respectively. Importantly, the expression of cell cycle regulatory gene CDC25A that has been implicated in multiple kinds of malignant transformation was significantly upregulated among the exposed males while downregulated among the exposed females. In conclusion, our studies have demonstrated significant correlations between e-waste disposing and POPs accumulation, DNA lesions and dysregulation of multiple DNA damage repair mechanisms in the residents of the e-waste exposed region.

Biomarkers to assess the efficiency of treatment with platinum-based drugs: what can metallomics add?

Since the approval of cisplatin as an antineoplastic drug, the medical and the scientific communities have been concerned about the side effects of platinum-based drugs, and this has been the dose-limiting factor that leads to reduced treatment efficiency. Another important issue is the intrinsic or acquired resistance of some patients to treatment. Identifying proper biomarkers is crucial in evaluating the efficiency of a treatment, assisting physicians in determining, at early stages, whether or not the patient presents resistance to the drug, minimizing severe side effects, and allowing them to redirect the established course of chemotherapy. A great effort is being made to identify biomarkers that can be used to predict the outcome of the treatment of cancer patients with platinum-based drugs. In this context, the metallomic approach has not yet been used to its full potential. Since the basis of these drugs is platinum, the monitoring of biomarkers containing this metal should be the natural approach to evaluate treatment progress. This review intends to show where the research in this field stands and points out some gaps that can be filled by metallomics.

Serum APE1 autoantibodies: a novel potential tumor marker and predictor of chemotherapeutic efficacy in non-small cell lung cancer

Apurinic/apyrimidinic endonuclease 1 (APE1), which has the dual functions of both DNA repair and redox activity, has been reported to be highly expressed in non-small cell lung cancer (NSCLC), and this appears to be a characteristic related to chemotherapy resistance. In this study, we identified serum APE1 autoantibodies (APE1-AAbs) in NSCLC patients and healthy controls by immunoblotting and investigated the expression of APE1-AAbs by indirect ELISA from the serum of 292 NSCLC patients and 300 healthy controls. In addition, serum APE1-AAbs level alterations of 91 patients were monitored before and after chemotherapy. Our results showed that serum APE1-AAbs can be detected in both NSCLC patients and healthy controls. Serum APE1-AAbs were significantly higher than those of healthy controls and closely related to APE1 antigen levels both in tumor tissues and the peripheral blood. Moreover, the change in levels of serum APE1-AAbs in NSCLC is closely associated with the response to chemotherapy. These results suggest that APE1-AAbs is a potential tumor marker and predictor of therapeutic efficacy in NSCLC.

Increased expression and function of P-glycoprotein in peripheral blood CD56+ cells is associated with the chemoresistance of non-small-cell lung cancer

PURPOSE

Chemoresistance is common among non-small-cell lung cancer (NSCLC), P-glycoprotein (P-gp), encoded by the human multi-drug-resistant MDR1 gene, and multidrug-resistance protein 1 (MRP1) might be major contributors. The aim of the present study was to develop an effective method to investigate the expression and function of P-gp in the peripheral CD56+ cells in order to clarify their correlation with the chemoresistance in NSCLC.

METHODS

Using microbead technology and a RT-qPCR methodology, we evaluated the expression levels of P-gp and MRP1 in the purified CD56+ cells in the chemoresistance and chemo-naive NSCLC patients compared with that in the healthy volunteers. Flow cytometric analysis was used to investigate the changes of P-gp function in the CD56+ cells between the three cohorts.

RESULTS

The MDR1 gene expression was elevated markedly (twofold-tenfold), and P-gp function was increased in the chemoresistance cohort compared with the chemo-naive and the healthy cohorts; whereas there was only about two times averagely elevated for the MRP1 gene expression. No statistical significance (p > 0.05) was seen with respect to the expression of MDR1 and MRP1, the function of P-gp between the chemo-naive and the healthy cohorts.

CONCLUSIONS

P-gp in peripheral CD56+ cells demonstrated possible clinical relevance as predictive biomarkers for the identification of chemoresistance in NSCLC, while MRP1 may not play a significant role in the drug resistance in NSCLC. The potential applications for this finding are provided evidence to screen the potential P-gp reversors and to diagnose and manage the chemoresistance in NSCLC patients.