Excision Repair Cross-complementing 1 mRNA Expression Research Articles

Chemoresistance in gastric cancer is attributed to the overexpression of excision repair cross-complementing 1 (ERCC1) caused by microRNA-122 dysregulation.

MicroRNAs are deemed as key regulators of gene expression. In particular, the elevated expression of excision repair cross-complementing 1 (ERCC1) significantly reduced the effectiveness of gastric cancer treatment by cisplatin (CDDP)-based therapies. In this paper, qRT-PCR and western blot were adopted to measure miR-122 and ERCC1 messenger RNA (mRNA) expression in all samples. Luciferase assay was carried out to verify the role of ERCC1 as a target of miR-122. The CCK-8 assay was carried out to study the effect of ERCC1 and miR-122 on cell survival and apoptosis. The results demonstrated that miR-122 expression was reduced in cisplatin-resistant gastric cancer. Using bioinformatic analysis, miR-122 was shown to target the 3'-UTR of human ERCC1. A dual-luciferase assay demonstrated that miR-122 downregulated ERCC1 expression, while the mutations in ERCC1 3'-UTR abolished its interaction with miR-122. Transfection of miR-122 mimics decreased the levels of ERCC1 mRNA and protein expression, while the transfection of miR-122 inhibitors increased the levels of both ERCC1 mRNA and protein expression. Furthermore, we found that overexpressed miR-122 promoted the proliferation of MKN74 cells and reduced their apoptotic by targeting ERCC1. In addition, the levels of miR-122 and ERCC1 were negatively correlated in gastric cancer samples. In summary, the reduced miR-122 expression may play an essential role in the induction of cisplatin-resistance by increasing ERCC1 expression.

The Predictive Role of ERCC1 Status in Oxaliplatin Based Neoadjuvant Therapy for Metastatic Colorectal Cancer (mCRC) to the Liver

Increased expression of excision repair cross-complementing 1 (ERCC1) in mCRC patients could be related to their response to Oxaliplatin based chemotherapy. We evaluated ERCC1 mRNA expression levels in primary bowel and liver metastases of 51 patients, and correlated with pathologic parameters and clinical outcomes. A significant negative correlation was detected between primary tumor ERCC1 and both the extent of clear surgical margins (P = 0.0011) and the percent of liver metastasis necrosis (P = 0.0167). No relationship was observed between ERCC1 expression and survival. Further study is needed to assess the promising role of ERCC1 expression as a predictive marker benefiting subgroups for Oxaliplatin.

ERCC1 mRNA expression as a postoperative prognostic marker in extrahepatic bile duct cancer.

No reliable biomarker for biliary tract cancer has yet been identified because of the varying composition of the cancer type, differences in tumor location, a mixture of curative and non-curative operations, and differences in operative methods. Fifty extrahepatic bile duct cancer patients, pathologically diagnosed with papillary or tubular adenocarcinoma who underwent a pancreatoduodenectomy with R0 resection, were included in the study. Messenger RNA (mRNA) expression levels were measured from formalin-fixed, paraffin-embedded samples by real-time reverse-transcription polymerase chain reaction. The preliminary analysis selected ten patients who have survived more than 5 years (LS group) and ten who had a relapse within 2 years (SS group). mRNA expression of seven target genes was examined, but only excision repair cross-complementing 1 (ERCC1) mRNA levels showed a significant difference between the LS and SS groups (median ERCC1: LS 26.5 vs. SS 9.7; p = 0.0073). The median survival time of patients with high ERCC1 levels was significantly longer than in patients with low ERCC1 levels (p = 0.0105). Thirty more patients with identical backgrounds were added to the study, and ERCC1 mRNA levels were measured in all 50 patients. Those with high ERCC1 mRNA levels had a significantly greater overall survival (OS) time compared with those with low ERCC1 levels (MST: 174 vs. 86 M; p = 0.048). Multivariate analysis found that an absence of lymph node metastases and high ERCC1 expression were significantly associated with improved OS. ERCC1 mRNA expression appears to be a useful prognostic biomarker for extrahepatic bile duct cancer with R0 resection.

ERCC1 siRNA ameliorates drug resistance to cisplatin in gastric carcinoma cell lines

The present study examined the effects of cisplatin (DDP) on gastric carcinoma cells by inhibiting the expression of excision repair cross-complementing 1 (ERCC1) using RNA interference (RNAi). mRNA and protein expression of ERCC1 were measured in various gastric carcinoma cell lines using reverse transcription polymerase chain reaction (RT-PCR) and western blot analysis. Cells were treated with different concentrations of DDP and the cell viability was measured using an MTT assay. The correlation between the expression of the ERCC1 gene and the resistance to DDP in the cells was determined. The specific ERCC1 small interfering RNA (siRNA) was synthesized and then transfected into SGC-7901/DDP cells. Alterations in intracellular ERCC1 mRNA expression and protein levels were detected using RT-PCR and western blot analysis, the number of apoptotic cells were measured using flow-cytometry and the cell viability was measured using an MTT assay. The gene expression of ERCC1 correlated with the resistance to DDP of the cells. mRNA expression of ERCC1 was significantly reduced 24 h following transfection of ERCC1 siRNA compared with the mock control group. In addition, the number of apoptotic cells was increased and cell viability was significantly decreased in the ERCC1 siRNA-transfected group compared with the mock control group, suggesting that the sensitivity of SGC-7901/DDP cells to DDP had significantly increased. Cells transfected with siRNA1, siRNA2 and siRNA3 were significantly more sensitive to DPP (161, 381 and 249%, respectively) compared with the mock controls (P<0.05). The results of the present study showed that drug resistance to DDP in gastric carcinoma is correlated with increased expression of ERCC1; therefore, inhibition of ERCC1 by siRNA may ameliorate resistance to DDP in gastric carcinoma.

Cinnamaldehyde/chemotherapeutic agents interaction and drug-metabolizing genes in colorectal cancer

Cinnamaldehyde is an active monomer isolated from the stem bark of Cinnamomum cassia, a traditional oriental medicinal herb, which is known to possess marked antitumor effects in vitro and in vivo. The aim of the present study was to examine the potential advantages of using cinnamaldehyde in combination with chemotherapeutic agents commonly used in colorectal carcinoma (CRC) therapy, as well as to investigate the effect of cinnamaldehyde on chemotherapeutic-associated gene expression. The synergistic interaction of cinnamaldehyde and chemotherapeutic agents on human CRC HT-29 and LoVo cells was evaluated using the combination index (CI) method. The double staining with Annexin V conjugated to fluorescein-isothiocyanate and phosphatidylserine was employed for apoptosis detection. The expression of drug-metabolizing genes, including excision repair cross‑complementing 1 (ERCC1), orotate phosphoribosyltransferase (OPRT), thymidylate synthase (TS), breast cancer susceptibility gene 1 (BRCA1) and topoisomerase 1 (TOPO1), all in HT-29 and LoVo cells, with or without the addition of cinnamaldehyde, was examined by quantitative polymerase chain reaction (PCR). Cinnamaldehyde had a synergistic effect on the chemotherapeutic agents cytotoxicity in HT-29 and LoVo cells. In addition, cinnamaldehyde suppressed BRCA1, TOPO1, ERCC1 and TS mRNA expression, except for OPRT expression, which was markedly upregulated. Our findings indicate that cinnamaldehyde appears to be a promising candidate as an adjuvant in combination therapy with 5-fluorouracil (5-FU) and oxaliplatin (OXA), two chemotherapeutic agents used in CRC treatment. The possible mechanisms of its action may involve the regulation of drug‑metabolizing genes.

Synergistic Anticancer Effects of Polyphyllin I and Evodiamine on Freshly-Removed Human Gastric Tumors

ObjectiveThe present study was designed to examine the anticancer effect of Traditional Chinese Medicine of polyphyllin I (PPI) and evodiamine (EVO) on freshly–removed gastric tumor tissues.MethodsSixty freshly–removed gastric tumor tissues were collected. Their sensitivity to PPI, EVO, platinum (Pt), 5-FU, irinotecan (CPT-11) were determined by histoculture drug response assay (HDRA). Those samples were also formalin-fixed and paraffin-embedded, which were used to examine the mRNA expression levels of aprataxin(APTX), excision repair cross-complementing 1(ERCC1), thymidylate synthase(TS) and topoisomerase I(TOPO1) by quantitative RT-PCR. The association of the gene expression levels and in vitro sensitivity were analyzed.ResultsPPI, EVO, Pt, 5-FU and CPT-11 had anticancer effects on the freshly-removed gastric tumor tissues with average inhibition rates of 20.64%±14.25% for PPI, 21.14%±13.43% for EVO, 50.57%±22.37% for Pt, 53.54%±22.03% for 5-FU, and 39.33%±24.79% for CPT-11, respectively. Combination of PPI and Pt, EVO and Pt, EVO and 5-FU had higher inhibition rates than any single drug of them (P<0.001, P = 0.028, P = 0.017, respectively). The mRNA expression levels of ERCC1 were correlated with Pt sensitivity (rho = −0.645, P<0.001); the mRNA expression levels of TS were correlated with 5-FU sensitivity (rho = −0.803, P<0.001). There were also weak but significant correlations between APTX mRNA expression levels and CPT-11 sensitivity (rho = −0.376, P = 0.017) or EVO sensitivity (rho = −0.322, P = 0.036). ERCC1 mRNA expression levels was markedly suppressed by the presentation of PPI (P = 0.001) and slightly suppressed by the presentation of EVO (P = 0.04); whereas, TS mRNA expression levels was markedly decreased by the presentation of EVO (P = 0.017) and slightly decreased by the presentation of PPI (P = 0.047).ConclusionPPI and EVO both could inhibit the activity of freshly-removed gastric tumor, and they could enhance the anticancer effect of Pt and 5-FU by reducing the mRNA expression levels of ERCC1 and TS.

Blood-based CHRNA3 single nucleotide polymorphism and outcome in advanced non-small-cell lung cancer patients

Nicotine acetylcholine receptors (nAChRs) are associated with resistance to gemcitabine, cisplatin and paclitaxel in non-small-cell lung cancer (NSCLC) cell lines. Three single nucleotide polymorphisms (SNPs) of CHRNA3, CHRNA5 and LOC123688 increase lung cancer risk. These SNPs may have influenced outcome in patients treated in our phase III trial. Stage IV NSCLC patients were treated with customized chemotherapy based on ERCC1 (excision repair cross-complementing 1) mRNA expression. Patients in the control arm received docetaxel/cisplatin; patients in the genotypic arm with low levels of ERCC1 received docetaxel/cisplatin; patients in the genotypic arm with high levels of ERCC1 received docetaxel/gemcitabine. DNA was extracted from lymphocytes, and CHRNA3 (rs1051730), CHRNA5 (rs16969968) and LOC123688 (rs8034191) SNPs were genotyped with the Taqman allele discrimination assay. A significant interaction was found for CHRNA3 and PS ( P = 0.02). In patients with PS 0, CT patients had a better response than both CC ( P = 0.01) and TT ( P = 0.02) patients, and patients in the low genotypic group also had a better response ( P = 0.01). When the CHRNA3 genotype was added in the multivariate analysis for progression-free survival, an improvement was observed in the low genotypic group in PS 0 patients ( P = 0.02). PS 0 patients in the low genotypic group with the CT genotype attained an 84% response rate, 12.1-month progression-free survival, and 19-month median survival. CHRNA3 (rs1051730) genotyping can improve customized chemotherapy based on tumor assessment of ERCC1 mRNA in stage IV NSCLC with PS 0.

Can We Customize Chemotherapy? Individualizing Cytotoxic Regimens in Advanced Non–Small-Cell Lung Cancer

Metastatic non–small-cell lung cancer remains a fatal disease with a median survival of < 1 year. A critical challenge is to develop predictive markers for customizing platinum-based treatment. The first studies focused on the excision repair cross-complementing 1 (ERCC1) gene in this difficult task. Several layers of evidence indicate that ERCC1 mRNA expression could be a predictive marker for cisplatin alone or in combination with certain drugs such as etoposide, gemcitabine, and 5-fluorouracil but not in combination with antimicrotubule drugs. Several retrospective studies demonstrated an impressive survival advantage for gemcitabine plus cisplatin but not for other combinations in tumors with low ERCC1 expression. A customized phase III ERCC1-based trial met the primary endpoint of improvement in response but not in survival, leading us to hypothesize that docetaxel might not be the most appropriate partner for cisplatin in the presence of low ERCC1 levels or for gemcitabine in the presence of high ERCC1 levels. A phase II study demonstrated the feasibility of combining carboplatin, gemcitabine, docetaxel, and vinorelbine according to ERCC1 and ribonucleotide reductase subunit M1 expression levels. These findings highlight the importance of continual learning, and decision-making strategies for customizing treatment should reflect the limitations of our knowledge.

Platinum Resistance Related to a Functional NER Pathway

Tobacco carcinogens induce DNA adducts that are repaired by the nucleotide excision repair (NER) pathway.1 Inhaled combustion-derived particles, such as cigarette smoke, cause a local pulmonary inflammatory response that is characterized by the influx of neutrophils into the airways. On entering the lung, neutrophils are activated and release reactive oxygen species and an array of proteins, such as myeloperoxidase. A significant reduction of NER in human alveolar epithelial cells was observed when they were cocultured with activated neutrophils.2 NER, a highly versatile pathway for DNA damage removal, is often dysfunctional in non-small cell lung cancer (NSCLC) and could, therefore, be the Achilles heel for customizing chemotherapy. NER removes numerous types of DNA helix-distorting lesions, including cisplatinand ultraviolet-induced photo products.1 Inherited defects in the NER process cause serious repair disorders: xeroderma pigmentosum (XP), with extreme risk of ultraviolet-induced skin cancer, and Cockayne syndrome. NER functions by a “cutand-paste” mechanism in which cisplatin damage recognition, local opening of the DNA helix around the lesion, damage excision, and gap filling occur in successive steps1,3–5 (Figure 1). NER is composed of two subpathways: global genome NER (GG-NER) and transcription-coupled NER (TC-NER), which share the same core mechanism but differ in the way lesions are recognized.6 NER-defective XP is classified into seven complementation groups, XPA to XPG. XPC and XPE are specifically defective in GG-NER, which repairs the damage on the nontranscribed strand, whereas the other XP groups involve deficiencies in both TC-NER and GG-NER.7 The first step in GG-NER is damage recognition by the heterodimer XPC/hHR23B, which binds with higher affinity to helix-distorting DNA lesions than to nondamaged, doublestranded DNA1 (Figure 1A). Various NER factors, including transcription factor IIH (TFIIH, a general transcription factor for RNA polymerase II), XPA, replication protein A (RPA), and XPG work together to repair DNA damage (Figure 1B). TFIIH can be divided into two subcomplexes: the core TFIIH (composed of XPB, p62, p52, p44, p34, and p8) and a cdk-activating kinase subcomplex (containing cdk7, cyclin H, and MAT1).7 Both subcomplexes are bridged by XPD. In NER, TFIIH unwinds the duplex DNA around the lesion to allow the recruitment of the NER factors XPA, RPA, XPG, and excision repair cross-complementing 1 (ERCC1)/XPF (Figure 1B). TFIIH, with the two helicases XPB and XPD, opens an approximately 30-base-long DNA segment around the platinum damage. This open intermediate is stabilized by RPA and XPA (Figure 1C). The DNA strand that contains the damaged base(s) is excised by the two NER endonucleases XPG and ERCC1/XPF (Figure 1D). XPG cleaves the damaged DNA strand 3= from the lesion, and ERCC1/XPF cleaves the damaged strand 5= from the lesion (Figure 1D). The resulting gap is filled by DNA polymerase or in the presence of replication factors8 (Figure 1E). Importantly, the ERCC1/XPF structure-specific nuclease has an additional role in the repair of cisplatin adducts besides its function in NER: the recombination repair of interstrand cross-links.9 Moreover, colocalization of ERCC1 foci and RAD51 foci in response to cisplatin treatment has recently been found and may represent recruitment of ERCC1/XPF to sites of recombination repair.10 Nevertheless, in addition to NER, cisplatininduced cytotoxicity requires the interaction of components from several different DNA damage-processing systems.11

ERCC1-Tailored Chemotherapy in Lung Cancer: The First Prospective Randomized Trial

The cancer death toll is one of the top health problems facing the industrialized world today. Lung cancer is the leading cause of cancer death in men and also increasingly in women. Novel therapeutic strategies need to be developed and existing therapies optimized to increase the survival rate of lung cancer patients. Improving systemic chemotherapy will have an impact on virtually 90% of all lung cancer patients, result in the cure of more patients with resected non–small-cell lung cancer (NSCLC), and improve the survival of patients with locally advanced/metastatic lesions. In this regard, rational treatment decision making based on an analysis of biomarkers of response and resistance to cytotoxic drugs seems to be a promising approach. Platinum has long been the mainstay of chemotherapy for lung cancer. Platinum cytotoxicity results from the disruption of the double-stranded DNA molecule in cells, mainly through the formation of intrastrand adducts. Nucleotide excision repair (NER) is the primary DNA repair mechanism that removes platinum-DNA adducts from genomic DNA. Excision repair cross-complementing 1 (ERCC1) is a critical gene on the NER pathway. A growing list of reports links cisplatin, carboplatin, and oxaliplatin resistance to ERCC1 mRNA levels in tumors. This relationship has been suggested for patients with gastric, bladder, ovarian, colorectal, and non–small-cell lung cancers. We recently showed that immunohistochemically evaluated ERCC1 levels are also predictive for the survival benefit afforded by adjuvant cisplatin-based chemotherapy in patients with totally resected stage I to IIIA NSCLC. In the treated group, ERCC1-negative tumors derived a substantial benefit from adjuvant cisplatin-based chemotherapy, whereas their ERCC1-positive counterparts did not. Interestingly, in patients randomly assigned to the observation arm, the subgroup with ERCC1-positive tumors had a better survival compared with those with ERCC1-negative tumors. This paradoxical status of ERCC1 (a good prognostic marker in untreated resected NSCLC patients and a poor predictor of efficient adjuvant chemotherapy) was recently confirmed by Zheng et al. The study by Cobo et al in this issue of the Journal of Clinical Oncology evaluated ERCC1 mRNA expression prospectively in an attempt to predict response to cisplatin-based or cisplatin-free regimens in stage IIIB or IV in NSCLC patients. In the control arm (no customization), patients received the well-established docetaxel/cisplatin combination. In the genotypic arm, patients were allocated to docetaxel/cisplatin or docetaxel/gemcitabine regimens respectively, according to whether low or high ERCC1 mRNA levels were detected. The study met its primary end point: response rates were significantly higher in the genotypic arm (50.3%) when compared with the control arm (39.3%). However, this difference was no longer significant after a strict intent-to-treat analysis. Most importantly however, the clinical relevance remains limited, given that there was no difference between the two arms in either progression-free survival or overall survival. How can one explain the negative results of such an innovative pioneering trial of customized chemotherapy? Technical issues clearly are crucial in the setting of biomarkerbased therapies. The study by Cobo et al is based on a series of assumptions. Evaluation of mRNA gene expression by reverse transcriptase polymerase chain reaction may be assessed safely in a convenient material: paraffin-embedded tissue. Laser capture tumor microdissection guarantees optimal tumor enrichment of the analyzed specimen. This quantitative technique produces a ratio of ERCC1 mRNA expression with housekeeping genes, thus simplifying allocation by predefining a threshold. In the trial under consideration, however, approximately 18% of the patients allocated to the genotypic arm were inassessable for ERCC1 due to insufficient tumor material. This percentage, along with patients excluded for other reasons (such as brain metastasis, protocol violations, and so on), led the authors to amend the protocol and increase recruitment by nearly 30%. The 18% dropout rate emphasizes the poor feasibility of this technique when insufficient tumor tissue is available. ERCC1 assessment was performed by Response Genetics (Los Angeles, CA), proprietor of the mRNA extraction procedure. The exact threshold defining high ERCC1 expression levels is unknown, but 43% of the patients were allocated to the high expression arm (high genotypic arm). It is therefore surprising that ranges for ERCC1 expression valve overlap between the high and low genotypic groups. Overall, major improvements of quantitative mRNA assessment are still required in the prospective setting. This technique should be compared and put into perspective with immunohistochemistry, a semiquantitative method that can be performed with a minimum amount of tissue and that has been validated for ERCC1 evaluation by two independent groups in the NSCLC setting. The design of the study by Cobo et al also merits discussion. The underlying hypothesis is that ERCC1 customization should improve clinical outcome (response rate and survival). This should be achieved by offering cisplatin-based therapy to ERCC1-negative JOURNAL OF CLINICAL ONCOLOGY E D I T O R I A L VOLUME 25 NUMBER 19 JULY 1 2007

Customizing Cisplatin Based on Quantitative Excision Repair Cross-Complementing 1 mRNA Expression: A Phase III Trial in Non–Small-Cell Lung Cancer

Although current treatment options for metastatic non-small-cell lung cancer (NSCLC) rely on cisplatin-based chemotherapy, individualized approaches to therapy may improve response or reduce unnecessary toxicity. Excision repair cross-complementing 1 (ERCC1) has been associated with cisplatin resistance. We hypothesized that assigning cisplatin based on pretreatment ERCC1 mRNA levels would improve response. From August 2001 to October 2005, 444 stage IV NSCLC patients were enrolled. RNA was isolated from pretreatment biopsies, and quantitative real-time reverse transcriptase PCR assays were performed to determine ERCC1 mRNA expression. Patients were randomly assigned in a 1:2 ratio to either the control or genotypic arm before ERCC1 assessment. Patients in the control arm received docetaxel plus cisplatin. In the genotypic arm, patients with low ERCC1 levels received docetaxel plus cisplatin, and those with high levels received docetaxel plus gemcitabine. The primary end point was the overall objective response rate. Of 444 patients enrolled, 78 (17.6%) went off study before receiving one cycle of chemotherapy, mainly due to insufficient tumor tissue for ERCC1 mRNA assessment. Of the remaining 346 patients assessable for response, objective response was attained by 53 patients (39.3%) in the control arm and 107 patients (50.7%) in the genotypic arm (P = .02). Assessment of ERCC1 mRNA expression in patient tumor tissue is feasible in the clinical setting and predicts response to docetaxel and cisplatin. Additional studies are warranted to optimize methodologies for ERCC1 analysis in small tumor samples and to refine a multibiomarker profile predictive of patient outcome.

Small interfering RNA-induced suppression of ERCC1 enhances sensitivity of human cancer cells to cisplatin

The level of excision repair cross-complementing 1 (ERCC1) gene expression, which is important in the repair of the cisplatin–DNA adducts, is reported to be related to the level of cisplatin resistance in tumor cells. Therefore, ERCC1 is an attractive target to confer increased cellular sensitivity to cisplatin-based chemotherapy. We designed, synthesized, and utilized small interfering RNAs (siRNAs) that were selective for ERCC1 and investigated their effectiveness in altering the repair capacity of the cells to cisplatin–DNA damage as well as the resistance of the cells to cisplatin. Twenty-four and 48 h after transfecting ERCC1 siRNA1 and siRNA2 targeting the two different regions of the ERCC1 transcript, both the ERCC1 mRNA and protein expression were significantly inhibited, whereas the mock or control siRNA had no effect. The suppression of ERCC1 expression in the HeLa S3 cells led to a decrease in the repair activity of cisplatin-induced DNA damage along with a decrease in the cell viability against platinum-based drugs, such as cisplatin, carboplatin, and oxaliplatin. A similar increased sensitivity to cisplatin and decreased repair activity were also observed for siRNA-mediated ERCC1 silencing in the MCF-7 and HCT116 cells. This study is the first to demonstrate the feasibility of utilizing ERCC1 siRNAs to specifically reduce the ERCC1 expression level in human cancer cells and provides direct evidence for the potential use of ERCC1 siRNA as a chemotherapy-sensitizing agent.

Single nucleotide polymorphisms and outcome in docetaxel–cisplatin-treated advanced non-small-cell lung cancer

Background: Platinum-based doublets are the standard chemotherapy for advanced non-small-cell lung cancer (NSCLC). Excision-repair cross-complementing 1 (ERCC1), xeroderma pigmentosum group D (XPD) and ribonucleotide reductase subunit M1 (RRM1) are essential to the repair of cisplatin DNA adducts. Multidrug resistance 1 (MDR1) has been related to antimicrotubule resistance. We assessed whether single nucleotide polymorphisms (SNPs) in ERCC1, XPD, RRM1 and MDR1, and ERCC1 mRNA expression, predicted survival in docetaxel–cisplatin-treated stage IV NSCLC patients.Patients and methods: Using the TaqMan 5′ nuclease assay, we examined ERCC1 118, XPD 751 and 312, RRM1 −37C/A, and MDR1 C3435T SNPs in peripheral blood lymphocytes (PBLs) obtained from 62 docetaxel–cisplatin-treated advanced NSCLC patients. ERCC1 expression was measured in RNA isolated from PBLs using real-time reverse transcriptase PCR.Results: Overall median survival was 10.26 months. Median survival was 9.67 months for 34 patients with ERCC1 118 C/T, 9.74 months for 17 patients with T/T, and not reached for 11 patients with C/C (P=0.04). Similar significant differences in time to progression were observed according to ERCC1 118 genotype (P=0.03). No other significant differences were observed.Conclusions: Patients homozygous for the ERCC1 118 C allele demonstrated a significantly better survival. ERCC1 SNP assessment could be an important component of tailored chemotherapy trials.

High specificity of quantitative excision repair cross-complementing 1 messenger RNA expression for prediction of minor histopathological response to neoadjuvant radiochemotherapy in esophageal cancer.

The excision repair cross-complementing 1 (ERCC1) gene is coding for a nucleotide excision repair protein involved in the repair of radiation- and chemotherapy-induced DNA damage. We examined the potential of quantitative ERCC1 mRNA expression to predict minor or major histopathological response to neoadjuvant radiochemotherapy (cisplatin, 5-fluorouracil, and 36 Gy of radiation) followed by transthoracic en bloc esophagectomy in patients with locally advanced esophageal cancer (cT(2-4), N(x), M(0)). Tissue samples were collected by endoscopic biopsy before treatment. RNA was isolated from biopsies, and quantitative real-time reverse transcriptase PCR assays were performed to determine ERCC1 mRNA expression. Relative mRNA levels (tumor/normal ratios) were calculated as (ERCC1/beta-actin in tumor)/(ERCC1/beta-actin in paired normal tissue). ERCC1 expression levels were correlated with the objective histopathological response in resected specimens. Histomorphological regression was defined as major response when resected specimens contained <10% of residual vital tumor cells or in case a pathologically complete response was achieved. Twelve of 36 tumors showed a major histopathological response, and 24 of 36 showed a minor histopathological response. Relative expression levels of ERCC1 of >1.09 were not associated with a major histopathological response (sensitivity, 62.5%; specificity, 100%) and 15 of 24 patients with minor histopathological response to the delivered neoadjuvant radiochemotherapy could be unequivocally identified. This association of dichotomized relative ERCC1 mRNA expression and histopathological response was statistically significant (P < 0.001). Relative expression levels of ERCC1 mRNA determined by quantitative real-time reverse transcriptase-PCR appear highly specific to predict minor response to our neoadjuvant radiochemotherapy protocol in patients with locally advanced esophageal cancer and could be applied to prevent expensive, noneffective, and potentially harmful therapies in a substantial number (42%) of patients.