Exon 19 of EGFR mutation in relation to the CA-repeat polymorphism in intron 1

Genetic polymorphism in the epidermal growth factor receptor gene predicts outcome in advanced non-small cell lung cancer patients treated with erlotinib

OBJECTIVES

Epidermal growth factor receptor (EGFR) mutations are important predictors of treatment response to tyrosine kinase inhibitors (TKIs) in patients with non-small cell lung cancer (NSCLC). However, some patients with mutations do not respond and some patients without mutations show response. We therefore need additional biomarkers to improve the selection of these patients for treatment. A promising candidate could be germline genetic variations in the EGFR gene that can alter protein expression or function and may influence the response to TKIs. Thus, the aim of this study was to evaluate the predictive role of genetic variations in the EGFR gene in advanced NSCLC patients treated with a TKI.

MATERIALS AND METHODS

Genotypes for -216G>T, -191C>A and 181946C>T in the EGFR gene were retrospectively evaluated by DNA sequencing and allele-specific PCR analysis in 331 Caucasian patients with advanced NSCLC. Genotypes were correlated with clinical characteristics, toxicity and outcome. A multivariate analysis was performed using Cox proportional hazards model while adjusting for clinically relevant factors including EGFR mutation status.

RESULTS

181946CT or TT genotypes showed an association with clinical outcome compared with patients with the 181946CC genotype (disease control rate (DCR), 68% versus 52%; P=0.049; progression-free survival (PFS), adjusted hazard ratio (HR)=0.74 (95% confidence interval (CI): 0.55-0.99); overall survival (OS), adjusted HR=0.73 (95% CI: 0.54-0.97)). Subgroup analysis demonstrated that the association may be most relevant in EGFR mutation-positive patients (PFS, adjusted HR=0.43 (95% CI: 0.22-0.82); OS, adjusted HR=0.47 (95% CI: 0.24-0.93)).

CONCLUSION

The 181946C>T polymorphisms in the EGFR gene seems to be a potential predictor of higher DCR, longer PFS and OS in advanced NSCLC patients treated with erlotinib, especially in EGFR mutation-positive patients. Thus, this SNP may be a new potential tool for selection of patients for treatment. Prospective randomized studies are wanted to confirm our data.

EGFR CA repeat polymorphism predict clinical outcome in EGFR mutation positive NSCLC patients treated with erlotinib

OBJECTIVES

Somatic mutations in the epidermal growth factor receptor (EGFR) are predictors of efficacy for treatment with the EGFR tyrosine kinase inhibitor erlotinib in non-small cell lung cancer (NSCLC). A CA repeat polymorphism in intron 1 of the EGFR gene influences the transcription of the EGFR gene. This study evaluates the association between the CA repeat polymorphism and outcome in NSCLC patients treated with erlotinib.

MATERIALS AND METHODS

Number of CA repeats in the EGFR gene was evaluated with PCR-fragment length analysis by capillary electrophoresis in 432 advanced NSCLC patients treated with erlotinib irrespective of EGFR mutation status. Patients were dichotomized into harboring short allele (CA≤16 in any allele) or long alleles (CA>16 in both alleles). Number of repeats was correlated with clinical characteristic and outcome. A subgroup analysis was performed based on the somatic EGFR mutation status.

RESULTS

In EGFR mutation positive patients (N=62) we demonstrate a significantly higher median progression free survival (HR=0.39 (0.22-0.70); p=0.002) and overall survival (HR=0.43 (0.23-0.78); p=0.006) in patients also harboring a short CA repeat length vs. a long (median follow-up time of 52.2 months). The result remained highly significant in a multivariate Cox proportional hazards model. This correlation was not seen in EGFR mutation negative patients.

CONCLUSION

Our study demonstrate that in EGFR mutation positive NSCLC patients treated with erlotinib a low number of CA repeats in intron 1 of the EGFR gene is a predictor for both longer progression free survival and overall survival.

Genetic variations in EGFR and ERBB4 increase susceptibility to cervical cancer

OBJECTIVES

Inherited genetic variability contributes to susceptibility to cervical cancer. We investigated the association of single nucleotide polymorphisms (SNPs) in the human epidermal growth factor receptor (ERBB) family with cervical cancer.

METHODS

We used the transmission disequilibrium test (TDT) to look for excessive transmission of tag single nucleotide polymorphisms (tSNPs) in ERBB family members EGFR, ERBB2, ERBB3, and ERBB4 in a large sample of women with invasive and in situ cervical cancer and their biological parents (628 trios). The study used a discovery set of trios (244) analyzed by Illumina GoldenGate in which SNPs reaching a P<.05 were re-tested by TaqMan in the combined set of 628. We also explored collaborative effects of different ERBB alleles.

RESULTS

Based on single SNP TDT tests we identified 16 significant SNPs in the discover stage and six of 14 SNPs that could be assayed by TaqMan were significantly overtransmitted in women with cervical cancer in the combined replication set. Four SNPs were located in intron 1 of EGFR and two SNPs in intron 24 of ERBB4. The EGFR variants are located near multiple enhancers, silencers, and the previously identified functional common polymorphisms in intron 1.

CONCLUSIONS

Our data provide evidence for the involvement of intron 1 EGFR variants and intron 24 ERBB4 variants in modulating risk for the development of in situ and invasive cervical cancer. These variants should be examined in additional populations and functional studies would be needed to confirm this hypothesis.

Association of intronic repetition of SLC26A4 gene with Hashimoto thyroiditis disease

Intronic microsatellites repeats were implicated in the pathogenic mechanisms of several diseases. SLC26A4 gene, involved in the genetic susceptibility of autoimmune thyroid disease (AITD), harbours large non-coding introns. Using the tandem repeat finder (TRF) Software, two new polymorphic microsatellite markers, rs59736472 and rs57250751, located at introns 10 and 20, respectively, were identified. A case-control design including 308 patients affected with AITD (146 GD, 90 HT and 72 PIM) and 212 unmatched healthy controls were performed for each marker (rs59736472, D7S2459 and rs57250751). Furthermore, we used PHASE 2.0 version to reconstruct haplotypes, Kolmogorov-Smirnov (KS) and the Clump analysis program for multivariate analysis. The fluorescent genotyping revealed three alleles (106,112 and 115 bp) for rs57250751 and 12 alleles for both D7S2459 and rs59736472 ranging from 134 to 156 bp and from 144 to 168 bp, respectively. The case-control analysis confirmed the positive association of D7S2459 with Hashimoto thyroiditis (HT) disease previously reported. Moreover, a significant association was found only with rs59736472 and HT disease. Haplotype-specific analysis showed that the 140-148-115 haplotype may increase the risk of HT (χ2=9.8, 1 df, P=0.0017, OR=2.07, IC [1.27-3.36]). Consequently, considering the number of repetitions of both D7S2459 and rs59736472, we found 15 alleles ranging from 45 to 59 repetitions. The case-control analysis showed a significant association of the 55 repetition with HT disease (χ2=6.32, 1 df, p c=0.012, OR=1.74, IC [1.1-2.76]). In conclusion, we suggest the association of longer alleles of intron 10 of SLC26A4 gene with HT disease.

Epidermal growth factor receptor in pancreatic cancer

Pancreatic cancer is the fourth leading cause of cancer related death. The difficulty in detecting pancreatic cancer at an early stage, aggressiveness and the lack of effective therapy all contribute to the high mortality. Epidermal growth factor receptor (EGFR) is a transmembrane glycoprotein, which is expressed in normal human tissues. It is a member of the tyrosine kinase family of growth factors receptors and is encoded by proto-oncogenes. Several studies have demonstrated that EGFR is over-expressed in pancreatic cancer. Over-expression correlates with more advanced disease, poor survival and the presence of metastases. Therefore, inhibition of the EGFR signaling pathway is an attractive therapeutic target. Although several combinations of EGFR inhibitors with chemotherapy demonstrate inhibition of tumor-induced angiogenesis, tumor cell apoptosis and regression in xenograft models, these benefits remain to be confirmed. Multimodality treatment incorporating EGFR-inhibition is emerging as a novel strategy in the treatment of pancreatic cancer.

Functional EGFR germline polymorphisms may confer risk for EGFR somatic mutations in non-small cell lung cancer, with a predominant effect on exon 19 microdeletions

Somatic mutations in the EGFR tyrosine kinase domain play a critical role in the development and treatment of non-small cell lung cancer (NSCLC). Strong genetic influence on susceptibility to these mutations has been suggested. To identify the genetic factors conferring risk for the EGFR tyrosine kinase mutations in NSCLC, a case-control study was conducted in 141 Taiwanese NSCLC patients by focusing on three functional polymorphisms in the EGFR gene [-216G/T, intron 1 (CA)n, and R497K]. Allelic imbalance of the EGFR -216G/T polymorphism was also tested in the heterozygous patients and in the NCI-60 cancer cell lines to further verify its function. We found that the frequencies of the alleles -216T and CA-19 are significantly higher in the patients with any mutation (P = 0.032 and 0.01, respectively), in particular in those with exon 19 microdeletions (P = 0.006 and 0.033, respectively), but not in the patients with L858R mutation. The -216T allele is favored to be amplified in both tumor DNA of lung cancer patients and cancer cell lines. We conclude that the local haplotype structures across the EGFR gene may favor the development of cellular malignancies and thus significantly confer risk to the occurrence of EGFR mutations in NSCLC, particularly the exon 19 microdeletions.

Epidermal growth factor receptor and K-RAS status in two cohorts of squamous cell carcinomas

Background

With the availability of effective anti-EGFR therapies for various solid malignancies, such as non-cell small lung cancer, colorectal cancer and squamous cell carcinoma of the head and neck, the knowledge of EGFR and K-RAS status becomes clinically important. The aim of this study was to analyse EGFR expression, EGFR gene copy number and EGFR and K-RAS mutations in two cohorts of squamous cell carcinomas, specifically anal canal and tonsil carcinomas.

Methods

Formalin fixed, paraffin-embedded tissues from anal and tonsil carcinoma were used. EGFR protein expression and EGFR gene copy number were analysed by means of immunohistochemistry and fluorescence in situ hybridisation. The somatic status of the EGFR gene was investigated by PCR using primers specific for exons 18 through 21. For the K-RAS gene, PCR was performed using exon 2 specific primers.

Results

EGFR immunoreactivity was present in 36/43 (83.7%) of anal canal and in 20/24 (83.3%) of tonsil squamous cell carcinomas. EGFR amplification was absent in anal canal tumours (0/23), but could be identified in 4 of 24 tonsil tumours.

From 38 anal canal specimens, 26 specimens were successfully analysed for exon 18, 30 for exon 19, 34 for exon 20 and 30 for exon 21. No EGFR mutations were found in the investigated samples. Thirty samples were sequenced for K-RAS exon 2 and no mutation was identified. From 24 tonsil specimens, 22 were successfully analysed for exon 18 and all 24 specimens for exon 19, 20 and 21. No EGFR mutations were found. Twenty-two samples were sequenced for K-RAS exon 2 and one mutation c.53C > A was identified.

Conclusion

EGFR mutations were absent from squamous cell carcinoma of the anus and tonsils, but EGFR protein expression was detected in the majority of the cases. EGFR amplification was seen in tonsil but not in anal canal carcinomas. In our investigated panel, only one mutation in the K-RAS gene of a tonsil squamous cell carcinoma was identified. This indicates that EGFR and K-RAS mutation analysis is not useful as a screening test for sensitivity to anti-EGFR therapy in anal canal and tonsil squamous cell carcinoma.

Lung cancer susceptibility among atomic bomb survivors in relation to CA repeat number polymorphism of epidermal growth factor receptor gene and radiation dose

Lung cancer is a leading cause of cancer death worldwide. Prevention could be improved by identifying susceptible individuals as well as improving understanding of interactions between genes and etiological environmental agents, including radiation exposure. The epidermal growth factor receptor (EGFR)-signaling pathway, regulating cellular radiation sensitivity, is an oncogenic cascade involved in lung cancer, especially adenocarcinoma. The cytosine adenine (CA) repeat number polymorphism in the first intron of EGFR has been shown to be inversely correlated with EGFR production. It is hypothesized that CA repeat number may modulate individual susceptibility to lung cancer. Thus, we carried out a case-cohort study within the Japanese atomic bomb (A-bomb) survivor cohort to evaluate a possible association of CA repeat polymorphism with lung cancer risk in radiation-exposed or negligibly exposed (<5 mGy) A-bomb survivors. First, by dividing study subjects into Short and Long genotypes, defined as the summed CA repeat number of two alleles < or = 37 and > or = 38, respectively, we found that the Short genotype was significantly associated with an increased risk of lung cancer, specifically adenocarcinoma, among negligibly exposed subjects. Next, we found that prior radiation exposure significantly enhanced lung cancer risk of survivors with the Long genotype, whereas the risk for the Short genotype did not show any significant increase with radiation dose, resulting in indistinguishable risks between these genotypes at a high radiation dose. Our findings imply that the EGFR pathway plays a crucial role in assessing individual susceptibility to lung adenocarcinoma in relation to radiation exposure.

Mina53, a novel c-Myc target gene, is frequently expressed in lung cancers and exerts oncogenic property in NIH/3T3 cells

PURPOSE

Mina53, whose expression is directly induced by c-Myc, is overexpressed in various cancers and plays an important role in cell growth. To clarify the involvement of Mina53 in lung cancers, we investigated its expression in human lung cancer tissues as well as in various lung cancer cell lines.

METHODS

Mina53 expression was determined by real-time RT-PCR, western blotting, and immunohistochemistry using lung cancer cell lines, normal human bronchial epithelial cells, and lung cancer tissues. Biological effects of Mina53 were evaluated by soft agar colony formation assay and tumorigenicity in nude mice using Mina53-transfected NIH/3T3 cells. cDNA microarray analysis was performed to determine the gene alteration by Mina53 and confirmation was made using real-time RT-PCR with mina53 expression plasmid or mina53 shRNA-transfected NIH/3T3 cells.

RESULTS

We observed that 62% of patients evidenced overexpression of Mina53 from the early clinical stages of lung cancer. Differences according to gender, smoking status, or histologic type were not statistically significant. Forced expression of Mina53 in NIH/3T3 cells induced cell transformation, and mina53-transfected NIH/3T3 clones produced tumors in nude mice, demonstrating that Mina53 has oncogenic potential. cDNA microarray revealed that 254 genes had altered expression in a mina53-transfected NIH/3T3 clone. Mina53 regulates several genes related to cell adhesion and metabolism, which have also been reported to be regulated by c-Myc. Genes regulated by Mina53, but not by c-Myc included cytokine/growth factor related genes such as EGFR, IL-6, and HGF.

CONCLUSION

Our results suggest that Mina53 plays an important role in carcinogenesis and may be a target for cancer prevention.

Mina53, a novel c-Myc target gene, is frequently expressed in lung cancers and exerts oncogenic property in NIH/3T3 cells

PURPOSE

Mina53, whose expression is directly induced by c-Myc, is overexpressed in various cancers and plays an important role in cell growth. To clarify the involvement of Mina53 in lung cancers, we investigated its expression in human lung cancer tissues as well as in various lung cancer cell lines.

METHODS

Mina53 expression was determined by real-time RT-PCR, western blotting, and immunohistochemistry using lung cancer cell lines, normal human bronchial epithelial cells, and lung cancer tissues. Biological effects of Mina53 were evaluated by soft agar colony formation assay and tumorigenicity in nude mice using Mina53-transfected NIH/3T3 cells. cDNA microarray analysis was performed to determine the gene alteration by Mina53 and confirmation was made using real-time RT-PCR with mina53 expression plasmid or mina53 shRNA-transfected NIH/3T3 cells.

RESULTS

We observed that 62% of patients evidenced overexpression of Mina53 from the early clinical stages of lung cancer. Differences according to gender, smoking status, or histologic type were not statistically significant. Forced expression of Mina53 in NIH/3T3 cells induced cell transformation, and mina53-transfected NIH/3T3 clones produced tumors in nude mice, demonstrating that Mina53 has oncogenic potential. cDNA microarray revealed that 254 genes had altered expression in a mina53-transfected NIH/3T3 clone. Mina53 regulates several genes related to cell adhesion and metabolism, which have also been reported to be regulated by c-Myc. Genes regulated by Mina53, but not by c-Myc included cytokine/growth factor related genes such as EGFR, IL-6, and HGF.

CONCLUSION

Our results suggest that Mina53 plays an important role in carcinogenesis and may be a target for cancer prevention.

Non-B DNA conformations as determinants of mutagenesis and human disease

Repetitive DNA motifs may fold into non-B DNA structures, including cruciforms/hairpins, triplexes, slipped conformations, quadruplexes, and left-handed Z-DNA, thereby representing chromosomal targets for DNA repair, recombination, and aberrant DNA synthesis leading to repeat expansion or genomic rearrangements associated with neurodegenerative and genomic disorders. Hairpins and quadruplexes also determined the relative abundances of simple sequence repeats (SSR) in vertebrate genomes, whereas strong base stacking has permitted the expansion of purine.pyrimidine-rich SSR during evolutionary time. SSR are enriched in regulatory and cancer-related gene classes, where they have been actively recruited to participate in both gene and protein functions. SSR polymorphic alleles in the population are associated with cancer susceptibility, including within genes that appear to share regulatory circuits involving reactive oxygen species.