Applicability of HIN-1, MGMT and RASSF1A promoter methylation as biomarkers for detecting field cancerization in breast cancer

Introduction

It has been shown in some articles that genetic and epigenetic abnormalities cannot only be found in tumor tissues but also in adjacent regions that appear histologically normal. This phenomenon is metaphorically called field cancerization or field defect. Field cancerization is regarded as clinically significant because it is assumed to be an important factor in local recurrence of cancer. As the field showing these molecular abnormalities may not be removed completely by surgery, these changes might lead to neoplasms and subsequent transformation to a tumor. We aimed to investigate the applicability of the methylation status of six tumor suppressor genes as biomarkers for detecting field cancerization in breast cancer.

Methods

The promoter methylation status of CCND2, DAPK1, GSTP1, HIN-1, MGMT and RASSF1A was determined by methylation-sensitive high-resolution melting (MS-HRM) analysis. MS-HRM methods for CCND2, MGMT and RASSF1A were developed in-house, primer sequences for DAPK1, GSTP1 and HIN-1 have already been published. Biopsy samples were taken from tumor, tumor-adjacent and tumor-distant tissue from 17 breast cancer patients. Normal breast tissues of four healthy women served as controls.

Results

All MS-HRM methods proved to be very sensitive. LODs were in the range from 0.1 to 1.5 %, LOQs ranged from 0.3 to 5.3 %. A total of 94 %, 82 % and 65 % of the tumors showed methylation of RASSF1A, HIN-1 and MGMT promoters, respectively. The methylation status of these promoters was significantly lower in tumor-distant tissues than in tumor tissues. Tumor-adjacent tissues showed higher methylation status of RASSF1A, HIN-1 and MGMT promoters than tumor-distant tissues, indicating field cancerization. The methylation status of the HIN-1 promoter in tumor-adjacent tissues was found to correlate strongly with that in the corresponding tumors (r = 0.785, p < 0.001), but not with that in the corresponding tumor-distant tissues (r = 0.312, p = 0.239).

Conclusions

Among the gene promoters investigated, the methylation status of the HIN-1 promoter can be considered the best suitable biomarker for detecting field cancerization. Further investigation is needed to test whether it can be used for defining surgical margins in order to prevent future recurrence of breast cancer.     

Tumour and serum MGMT promoter methylation and protein expression in glioblastoma patients

Introduction

Methylation of the promoter of the MGMT gene and MGMT protein expression are recognized as predictive markers for response to alkylating chemotherapy in glioblastoma (GB).

Material and methods

We have assessed MGMT methylation with the methylation-specific polymerase chain reaction (MSP) in tumor samples from 70 GB patients and in serum samples from 37 of these patients. We have also assessed MGMT protein expression by immunohistochemical (IHC) analysis in tissue samples from 63 of these patients.

Results

We found concordance between MGMT methylation status in tissue and serum (Cohen??s Kappa = 0.586; p<0.0001). MSP for detection of non-methylated MGMT promoter in serum showed a sensitivity of 95.4% and a specificity of 60%, while the IHC methylation test showed a low specificity (8.9%). Patients whose MGMT promoter was methylated in tissue attained longer progression-free and overall survival. In the multivariate analysis, serum MGMT promoter methylation emerged as an independent factor for longer progression-free and overall survival.

Conclusion

Serum-based MGMT methylation analysis offers a promising alternative to tumor-based MGMT analysis in cases where tissue samples are unavailable.     

LINE-1 hypomethylation in gastric cancer, detected by bisulfite pyrosequencing, is associated with poor prognosis

Background

Genome-wide DNA hypomethylation plays an important role in genomic instability and carcinogenesis. DNA methylation in the long interspersed nucleotide element-1, L1 (LINE-1) repetitive element is a good indicator of the global DNA methylation level. In some types of human neoplasms, LINE-1 methylation level is attracting interest as a predictive marker for patient prognosis. However, the prognostic significance of LINE-1 hypomethylation in gastric cancer remains unclear.

Methods

Using 203 resected gastric cancer specimens, we quantified LINE-1 methylation using bisulfite-pyrosequencing technology. A Cox proportional hazards model was used to calculate the hazard ratio (HR), adjusted for the clinical and pathological variables.

Results

Gastric cancers showed significantly lower LINE-1 methylation levels compared to matched normal gastric mucosa (p < 0.0001; n = 74). Tumoral LINE-1 methylation range was 11.6–97.5 on a 0–100 scale (n = 203; mean 71.4, median 74.4, standard deviation 12.9). LINE-1 hypomethylation was significantly associated with shorter overall survival [log-rank p = 0.029; univariate HR 2.01, 95 % confidence interval (CI) 1.09–3.99, p = 0.023; stage-matched HR 1.88, 95 % CI 1.02–3.74, p = 0.041; multivariate HR 1.98, 95 % CI 1.04–4.04, p = 0.036]. No significant effect modification was observed by any of the covariates in survival analysis (all p interaction >0.25).

Conclusions

LINE-1 hypomethylation in gastric cancer is associated with shorter survival, suggesting that it has potential for use as a prognostic biomarker.     

宫颈癌组织中DAPK基因启动子甲基化的研究

背景与目的:已有研究表明DNA异常甲基化在肿瘤的发生、发展中发挥了重要作用.本研究旨在探讨宫颈癌组织中DAPK(death-associated protein kinase)启动子甲基化与基因失活的关系.方法:应用甲基化特异性PCR (methylation-specific PCR,MSP)技术检测52例宫颈癌、60例宫颈上皮内瘤样病变(cervical intraepithelial neoplasia,CIN)和20例正常宫颈鳞状上皮DAPK启动子甲基化状况,应用免疫组化方法检测其蛋白表达;分析DAPK启动子甲基化和基因失活与宫颈癌临床病理因素之间的关系.结果:正常宫颈组织不存在DAPK基因启动子CpG岛甲基化,而CIN和宫颈癌中的DAPK甲基化率分别为18.3%(11/60)、65.4%(34/52),三者之间的差异有统计学意义(P<0.05).宫颈鳞癌的DAPK甲基化率明显高于腺癌(分别为80.0%和16.7%),其差异有统计学意义(P<0.001).DAPK启动子甲基化和DAPK蛋白表达之间呈负相关(r=-0.849,P<0.001).结论:DAPK启动子CpG岛甲基化可导致基因失活,并可能参与宫颈癌的发生.     

Identification of the methylation of p14ARF promoter as a novel non-invasive biomarker for early detection of lung cancer

Background

Recent diagnostic procedure advances have greatly improved early lung cancer detection. However, the invasive, unpleasant and inconvenient nature of current diagnostic procedures limits their application. There is a great need of novel non-invasive biomarkers for early lung cancer diagnosis. In the present study, we intend to determine whether the blood signatures of p14ARF promoter methylation are suitable for early detection of lung cancer.

Methods

The study aimed to assess the probability of p14ARF promoter methylation in plasma samples to detect early lung cancer using nested methylation-specific PCR in the training set consisted of tumor tissues and paired blood. Besides, we were further to discuss the difference in time to progression between methylation and unmethylation of p14ARF promoter using univariate and multivariate analysis.

Results

The methylation of p14ARF promoter was detected in 33.6 % of tumor tissues, and 12.1 and 25.2 % in distant-cancer mucosa and matched plasma, respectively, and our study has also demonstrated the positive correlation between them by Pearson’s test (r = 0.300). The tumor-free survival time of the unmethylation of p14ARF promoter is significantly longer than that of the methylation of p14ARF promoter in tumor tissues (χ ² = 7.149, P = 0.008).

Conclusion

The methylation of p14ARF promoter in plasma samples has strong potential as a novel non-invasive biomarker for early detection of lung cancer, and the methylation of p14ARF promoter was considered as prognostic factor in our study.     

Prostate Cancer Metastasis to the Stomach: 9 Years after the Initial Diagnosis—Case Report and a Literature Review

Introduction

Gastric cancer (GC) is one of the leading causes of cancer-related death in Iran. Genome stability is one of the main genetic issues in cancer biology which is governed via the different repair systems such as DNA mismatch repair (MMR). A clear correlation between MMR defects and tumor progression has been shown. Beside the genetic mutations, epigenetic changes also have a noticeable role in MMR defects.

Methods

Here, we assessed promoter methylation status and the level of hMLH1mRNA expression as the main component of MMR system in 51 GC patients using the methylation-specific PCR and real-time PCR, respectively. Moreover, we performed a promoter methylation study of the E-cadherin gene promoter.

Results

It was observed that, 12 out of 39 cases (23.5 %) had hMLH1 overexpression. Hypermethylation of hMLH1 and E-cadherin promoter regions were observed in 25.5 and 36.4 %, respectively. Although, there was no significant correlation between hMLH1 mRNA expression and clinicopathological features, there are significant correlations between E-cadherin promoter methylation and tumor stage (p?=?0.028) and location (p?=?0.025). The rate of hMLH1 promoter methylation in this study was lower than that in the other population, showing the importance of the other mechanisms, in gastric tumorigenesis.

Conclusion

The results of this study indicate that DNA repair system is adversely affected by hypermethylation of hMLH1 in a fraction of gastric cancer patients. Additionally, E-cadherin hypermethylation seen in a subset of our gastric cancer patients is consistent with other reports showing correlation with aggressiveness and metastasis of gastric cancer.     

PEG1/MEST and IGF2 DNA methylation in CIN and in cervical cancer

Introduction

Although most invasive cervical cancer (ICC) harbor <20 human papillomavirus (HPV) genotypes, use of HPV screening to predict ICC from HPV has low specificity, resulting in multiple and costly follow-up visits and overtreatment. We examined DNA methylation at regulatory regions of imprinted genes in relation to ICC and its precursor lesions to determine if methylation profiles are associated with progression of HPV-positive lesions to ICC.

Materials and methods

We enrolled 148 controls, 38 CIN and 48 ICC cases at Kilimanjaro Christian Medical Centre from 2008 to 2009. HPV was genotyped by linear array and HIV-1 serostatus was tested by two rapid HIV tests. DNA methylation was measured by bisulfite pyrosequencing at regions regulating eight imprinted domains. Logistic regression models were used to estimate odd ratios.

Results

After adjusting for age, HPV infection, parity, hormonal contraceptive use, and HIV-1 serostatus, a 10 % decrease in methylation levels at an intragenic region of IGF2 was associated with higher risk of ICC (OR 2.00, 95 % CI 1.14–3.44) and cervical intraepithelial neoplasia (CIN) (OR 1.51, 95 % CI 1.00–2.50). Methylation levels at the H19 DMR and PEG1/MEST were also associated with ICC risk (OR 1.51, 95 % CI 0.90–2.53, and OR 1.44, 95 % CI 0.90–2.35, respectively). Restricting analyses to women >30 years further strengthened these associations.

Conclusions

While the small sample size limits inference, these findings show that altered DNA methylation at imprinted domains including IGF2/H19 and PEG1/MEST may mediate the association between HPV and ICC risk.     

Nativity disparities in late-stage diagnosis and cause-specific survival among Hispanic women with invasive cervical cancer: an analysis of Surveillance, Epidemiology, and End Results data

Purpose

While cervical cancer screening and risk behaviors have been found to vary among US- and foreign-born Hispanic women, many cancer epidemiology studies have conceptualized Hispanics as a homogenous group. Here, we examine differences in cervical cancer stage at diagnosis and survival among Hispanic women by nativity.

Methods

We use data from the Surveillance, Epidemiology, and End Results program, 1998–2008. Nativity was based on place of birth and was categorized as US versus foreign born. Distant and regional tumors were classified as late stage, while local tumors were classified as early stage.

Results

Forty-seven percent of cases of invasive cervical cancer among Hispanics were diagnosed at a late stage, and over half of invasive cervical cancer cases were among foreign-born women. Foreign-born Hispanic women were significantly more likely than US-born Hispanics to have late-stage diagnosis, after adjusting for age at diagnosis and tumor histology (adjusted odds ration = 1.09, p value = 0.003). There was heterogeneity in the association between nativity and survival by stage at diagnosis. Among cases with early-stage diagnosis, survival was poorer among foreign-born versus US-born Hispanics after adjusting for age at diagnosis, histology, and cancer-directed therapy [adjusted hazard ratios (HR) = 1.31, p value = 0.030]. However, among cases with late-stage diagnosis, survival was better among foreign-born Hispanics (adjusted HR = 0.81, p value < 0.001).

Conclusions

We hypothesize that nativity differences in survival may be indicative of diverse risk, screening, and treatment profiles. Given such differences, it may be inappropriate to aggregate Hispanics as a single group for cervical cancer research.     

IDH1/2 gene status defines the prognosis and molecular profiles in patients with grade III gliomas

Background

The discovery of isocitrate dehydrogenase 1 and 2 gene (IDH1/2) mutations has enabled grade III glioma to be divided into mutated and wild-type IDH1/2 groups, which are known to carry different prognosis and molecular features. However, detailed subgroup analysis of grade III glioma is limited. To address this, we investigated molecular and prognostic features of grade III glioma with and without IDH1/2 mutation.

Methods

We retrospectively analyzed 115 grade III glioma patients. Clinical parameters were obtained from medical records. The mutation of IDH1/2 and TP53 was analyzed by direct sequencing. O⁶-methylguanine methyltransferase gene (MGMT) gene promoter methylation status was determined by methylation-specific polymerase chain reaction. Detection of chromosome copy number changes of 1p, 7p (EGFR), 9p (CDKN2A), 10q (PTEN), and 19q was carried out by multiple ligation-dependent probe amplification. Patients were divided into two groups, mutated IDH1/2 and wild-type IDH1/2, for correlation with the factors analyzed.

Results

In our series, as previously reported, IDH1/2 mutation was an independent prognostic marker for improved progression-free and overall survival (OS) (P < 0.0001 and P < 0.0001, respectively) in patients with grade III gliomas. Subgroup analysis found that incomplete resection, 7p gain, and TP53 mutation were independent prognostic factors of poor outcome in grade III glioma patients with mutated IDH1/2 (P = 0.0092, P = 0.015 and P = 0.026, respectively), while there were none in patients with wild-type IDH1/2.

Conclusions

IDH1/2 gene status was significantly associated with prognosis in grade III gliomas. Subgroup analysis found that poor prognostic factors existed even in patients with IDH1/2 mutation.     

Dietary aflatoxin B1 intake, genetic polymorphisms of CYP1A2, CYP2E1, EPHX1, GSTM1, and GSTT1, and gastric cancer risk in Korean

Purpose

We investigated the effects of aflatoxin B1 (AFB1) intake, genetic polymorphisms of AFB1 metabolic enzymes, and interactions between the polymorphisms and intake of AFB1 with regard to the risk of gastric cancer in Korean.

Methods

The participants in the study included 477 gastric cancer patients and 477 age- and sex-matched control subjects. Direct interviews and a structured questionnaire were used to determine the level of exposure to AFB1, and the GoldenGate assay and multiplex polymerase chain reaction were used for genotypic analyses of the cytochrome P450 1A2 (CYP1A2), cytochrome P450 1E1, epoxide hydrolase 1, and glutathione S-transferase genes.

Results

The probable daily intake of AFB1 was significantly higher among gastric cancer patients than among control subjects (cases vs. controls: 1.91 ± 0.87 vs. 1.65 ± 0.72 ng/kg bw/day, p < 0.0001), and increased AFB1 intake was significantly associated with an elevated risk of gastric cancer (odds ratio 1.94; 95 % confidence interval 1.43–2.63). However, genetic polymorphisms of AFB1 metabolic enzymes were not associated with gastric cancer, with the exception of CYP1A2. Moreover, there was no interaction between AFB1 intake and the genotypes of metabolic enzymes that affect gastric cancer risk.

Conclusions

Our results suggest that dietary AFB1 exposure might be associated with a risk of gastric cancer. However, the effect of AFB1 on gastric carcinogenesis may not be modulated by genetic polymorphisms of AFB1 metabolic enzymes.     

Cervical screening, high-grade squamous lesions, and cervical cancer in illicit drug users

Background and purpose

Women who use illicit drugs (“drug users”) are exposed to human papillomaviruses (HPVs) from lifestyle risks that include sex risk behaviors, human immunodeficiency virus infection, and high levels of tobacco smoking. Both HPVs and tobacco smoking are recognized causes of cervical cancer, but little is known about risk in drug users. We sought to examine risk of cervical neoplasia and to estimate cervical screening prevalence in drug users compared to non-drug-users in Australia.

Methods

Our study linked hospital admission records of women aged 20–54 in 2000–2007 to Pap Test Register and Cancer Registry records for 19,699 with an illicit drug–related admission and 194,089 without. We designed a nested case–control study of risk of cervical intraepithelial neoplasia (CIN) 2/3 and cervical cancer and a cross-sectional study of screening prevalence in this cohort of women.

Results

Drug users were less likely than non-users to be screened in the past 3 years (crude prevalence 47 vs 58 %; prevalence ratio 0.80; 95 % CI 0.78–0.81). Odds ratios (ORs) in drug users, adjusted for cervical screening history and smoking, were 1.13 (95 % CI 1.04–1.23) for CIN 2/3 and 1.43 (95 % CI 0.96–2.15) for cervical cancer. The adjusted ORs in each case were similar in cannabinoid users and users of other drugs.

Conclusions

The increased risks of CIN 2/3 and cervical cancer we observed are probably due to sex risk behaviors and their associated high risk of HPV. Interventions in drug users, such as HPV vaccination and barrier contraception and more cervical screening, might reduce the risk of cervical neoplasia.     

Aberrant promoter methylation of the RASSF1A and APC genes in epithelial ovarian carcinoma development

Purpose

Tumor suppressor gene (TSG) silencing through promoter hypermethylation plays an important role in cancer development. The aim of this study was to assess the extent of methylation of the RASSF1A and APC TSG promoters in ovarian epithelial adenomas, low malignant potential tumours and carcinomas in order to reveal a role for epigenetic TSG silencing in the development of these ovarian malignancies.

Method

The promoter methylation status of the RASSF1A and APC genes was assessed in 19 benign cystadenomas, 14 low malignant potential (LMP) tumours, and 86 carcinomas using methylation specific PCR (MSP).

Results

The methylation frequencies of the RASSF1A and APC gene promoters in benign cystadenomas were found to be 37?% and 16?%, respectively. The LMP tumours exhibited RASSF1A and APC gene promoter methylation frequencies of 50?% and 28?%, respectively, whereas the carcinomas exhibited methylation frequencies of 58?% and 29?%, respectively. Methylation of either the RASSF1A or the APC gene promoter was encountered in 58?% of the invasive carcinomas.

Conclusion

The observed aberrant methylation frequencies of the RASSF1A and APC gene promoters indicate that an accumulation of epigenetic events at these specific TSG promoters may be associated with the malignant transformation of benign cystadenomas and LMP tumours to carcinomas.     

Validation of DNA promoter hypermethylation biomarkers in breast cancer — a short report

Purpose

DNA promoter hypermethylation of tumor suppressor genes is known to occur early in cancer development, including breast cancer. To improve early breast cancer detection, we aimed to investigate whether the identification of DNA promoter hypermethylation might be of added value.

Methods

The methylation status of a panel of 19 candidate genes (AKR1B1, ALX1, ARHGEF7, FZD10, GHSR, GPX7, GREM1, GSTP1, HOXD1, KL, LHX2, MAL, MGMT, NDRG2, RASGRF2, SFRP1, SFRP2, TM6SF1 and TMEFF2) was determined in formalin-fixed paraffin-embedded normal breast and breast cancer tissue samples using gel-based methylation-specific PCR (MSP).

Results

The promoters of the AKR1B1, ALX1, GHSR, GREM1, RASGRF2, SFRP2, TM6SF1 and TMEFF2 genes were found to be significantly differentially methylated in normal versus malignant breast tissues. Based on sensitivity, specificity and logistic regression analyses the best performing genes for detecting breast cancer were identified. Through multivariate analyses, we found that AKR1B1 and TM6SF1 could detect breast cancer with an area under the curve (AUC) of 0.986 in a receiver operating characteristic (ROC) assessment.

Conclusions

Based on our data, we conclude that AKR1B1 and TM6SF1 may serve as candidate methylation biomarkers for early breast cancer detection. Further studies are underway to evaluate the methylation status of these genes in body fluids, including nipple aspirates and blood.     

Efficacy of bevacizumab-containing chemotherapy for non-squamous non-small cell lung cancer with bone metastases

Purpose

Skeletal-related events (SREs) negatively affect the quality of life of patients with cancer. Vascular endothelial growth factor receptor (VEGFR)-targeted therapy is effective against bone metastasis in animal models, but the clinical efficacy of anti-VEGFR inhibitors against bone metastases remains unclear. Therefore, we aimed to investigate the efficacy of chemotherapy with bevacizumab, an anti-VEGF antibody, against bone metastases.

Methods

We retrospectively reviewed consecutive patients with non-squamous non-small cell lung cancer who received first-line platinum-based chemotherapy with zoledronic acid at Shizuoka Cancer Center between 2007 and 2011.

Results

Of 25 patients, 13 received bevacizumab-based chemotherapy (BEV group) and 12 received chemotherapy without bevacizumab (non-BEV group). The overall response (54 vs. 8 %, p = 0.01) and disease control (100 vs. 50 %, p = 0.01) rates were higher in the BEV group than in the non-BEV group. The bone-specific response (23 vs. 0 %, p = 0.038) and disease control (100 vs. 67 %, p = 0.01) rates were also higher in the BEV group. The median time to progression (TTP) for bone metastases was higher in the BEV group (13.7 vs. 4.3 months, p = 0.06), whereas that for overall disease was similar between the groups (5.7 vs. 2.6 months, p = 0.17). The proportions of patients with SREs were 23 and 50 % in the BEV and non-BEV groups, respectively (p = 0.16).

Conclusion

Bevacizumab might potentiate the antitumor activity of chemotherapy against systemic disease and bone metastases, prolonging bone-specific TTP and reducing the incidence of SRE.     

Multiple human papillomavirus infection with or without type 16 and risk of cervical intraepithelial neoplasia among women with cervical cytological abnormalities

Purpose

To evaluate the impact of multiple human papillomavirus (HPV) infections on the risk of cervical intraepithelial neoplasia grade 3 or worse (CIN3+) in subjects with cervical cytological abnormalities.

Methods

A cross-sectional study of 3,842 women attending a colposcopy service was carried out. Genotyping of 18 high-risk, seven low-risk, and two undefined-risk HPVs was carried out by the INNO-LiPA genotyping system.

Results

The final colposcopic/pathological diagnoses were as follows: 1,933 (50.3 %) subjects were negative; 1,041 (27.1 %) CIN1; 280 (7.3 %) CIN2; 520 (13.5 %) CIN3; and 68 (1.8 %) invasive cervical cancer. The prevalence of HPV infection was 75.8 % (2,911/3,842), whereas multiple HPVs were detected in 34.5 % of HPV-positive subjects (2,255/3,842). The adjusted risks of CIN3+ in the group with multiple compared to the group with single infection were 2.31 (95 % CI = 1.54–3.47), among HPV16-positive women, and 3.25 (95 % CI = 2.29–4.61, p = 0.21 compared with HPV16-positive subjects), in HPV16-negative subjects. Out of a total of 1,285 subjects with mild lesions, followed up for a median of 16.1 months (interquartile range = 8.9–36.8), the rate of progression to CIN2–3 was 0.6 % (5/541) among subjects negative or with low-risk HPVs, 1.7 % (8/463) among those with single high-risk HPV, and 5 % (14/281, p < 0.001 compared with HPV-negative/low-risk HPV and p = 0.038 compared with single high-risk HPV) among those with multiple high-risk HPVs.

Conclusions

Among women with cervical cytological abnormalities, infection by multiple high-risk HPVs increased the risk of CIN3+ in both HPV16-positive and HPV16-negative subjects. These findings suggest a potential synergistic interaction between high-risk HPVs, favoring the progression of CIN lesions.     

Le polymorphisme −308 G>A du promoteur du gène codant le TNF-α n’est pas associé au cancer cervical en Tunisie

Objective

We assessed the polymorphism G>A at position 308 of the promoter of the gene encoding the TNF-α as a risk factor for cervical cancer in Tunisia. We also investigated whether this polymorphism is associated with histological type and/or FIGO stage of cervical tumor.

Materials and methods

Polymorphism G>A at position 308 of the promoter of the gene encoding the TNF-α is analyzed by ARMS-PCR in 103 Tunisian patients with cervical cancer and 138 healthy Tunisian women. The search for associations between this polymorphism and cervical cancer is based on the χ² test or Fisher’s exact test.

Results

The G allele is more frequent than the A allele in patients (63.11%) and healthy controls (65.58%). The heterozygous genotype GA is the most represented with a frequency of 56.31% in patients and 52.90% in controls. Homozygous genotypes GG and AA were found respectively at 34.95 and 8.74% patients and 39.13 and 7.97% healthy controls. Comparing the distribution of genotype frequencies between patients and healthy controls revealed no significant differences neither between allele A (AA + GA vs. GG) and the rest (p = 0.5070), nor between the G allele (GG vs. GA + AA) and the rest (p = 0.8309).

Conclusion

The ?308 G/A polymorphism of TNF-α gene promoter is not associated with cervical cancer or the stage and histological type of cervical tumor in Tunisia.     

MGMT gene promoter methylation correlates with tolerance of temozolomide treatment in melanoma but not with clinical outcome

Background:

Despite limited clinical efficacy, treatment with dacarbazine or temozolomide (TMZ) remains the standard therapy for metastatic melanoma. In glioblastoma, promoter methylation of the counteracting DNA repair enzyme O⁶-methylguanine-DNA-methyltransferase (MGMT) correlates with survival of patients exposed to TMZ in combination with radiotherapy. For melanoma, data are limited and controversial.

Methods:

Biopsy samples from 122 patients with metastatic melanoma being treated with TMZ in two multicenter studies of the Dermatologic Cooperative Oncology Group were investigated for MGMT promoter methylation. We used the COBRA (combined bisulphite restriction analysis) technique to determine aberrant methylation of CpG islands in small amounts of genomic DNA isolated from paraffin-embedded tissue sections. To detect aberrant methylation, bisulphite-treated DNA was amplified by PCR, enzyme restricted, and visualised by gel electrophoresis.

Results:

Correlation with clinical data from 117 evaluable patients in a best-response evaluation indicated no statistically significant association between MGMT promoter methylation status and response. A methylated MGMT promoter was observed in 34.8% of responders and 23.4% of non-responders (P=0.29). In addition, no survival advantage for patients with a methylated MGMT promoter was detectable (P=0.79). Interestingly, we found a significant correlation between MGMT methylation and tolerance of therapy. Patients with a methylated MGMT promoter had more severe adverse events, requiring more TMZ dose reductions or discontinuations (P=0.007; OR 2.7 (95% CI: 1.32–5.7)). Analysis of MGMT promoter methylation comparing primaries and different metastases over the clinical course revealed no statistical difference (P=0.49).

Conclusions:

In advanced melanoma MGMT promoter, methylation correlates with tolerance of therapy, but not with clinical outcome.