Aberrant methylation of mutL homolog 1 is associated with increased risk of non-small cell lung cancer

Discrimination of Lung Cancer and Benign Lung Diseases Using BALF Exosome DNA Methylation Profile

Benign lung diseases are common and often do not require specific treatment, but they pose challenges in the distinguishing of them from lung cancer during low-dose computed tomography (LDCT). This study presents a comprehensive methylation analysis using real-time PCR for minimally invasive diagnoses of lung cancer via employing BALF exosome DNA. A panel of seven epigenetic biomarkers was identified, exhibiting specific methylation patterns in lung cancer BALF exosome DNA. This panel achieved an area under the curve (AUC) of 0.97, with sensitivity and specificity rates of 88.24% and 97.14%, respectively. Each biomarker showed significantly higher mean methylation levels (MMLs) in both non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC) compared to non-cancer groups, with fold changes from 1.7 to 13.36. The MMLs of the biomarkers were found to be moderately elevated with increasing patient age and smoking history, regardless of sex. A strong correlation was found between the MMLs and NSCLC stage progression, with detection sensitivities of 79% for early stages and 92% for advanced stages. In the validation cohort, the model demonstrated an AUC of 0.95, with 94% sensitivity and specificity. Sensitivity for early-stage NSCLC detection improved from 88.00% to 92.00% when smoking history was included as an additional risk factor.

Role of DNA Methylation in the Resistance to Therapy in Solid Tumors

Despite the recent advances in chemotherapeutic treatments against cancer, some types of highly aggressive and invasive cancer develop drug resistance against conventional therapies, which continues to be a major problem in the fight against cancer. In recent years, studies of alterations of DNA methylome have given us a better understanding of the role of DNA methylation in the development of tumors. DNA methylation (DNAm) is an epigenetic change that promotes the covalent transfer of methyl groups to DNA. This process suppresses gene expression through the modulation of the transcription machinery access to the chromatin or through the recruitment of methyl binding proteins. DNAm is regulated mainly by DNA methyltransferases. Aberrant DNAm contributes to tumor progression, metastasis, and resistance to current anti-tumoral therapies. Aberrant DNAm may occur through hypermethylation in the promoter regions of tumor suppressor genes, which leads to their silencing, while hypomethylation in the promoter regions of oncogenes can activate them. In this review, we discuss the impact of dysregulated methylation in certain genes, which impact signaling pathways associated with apoptosis avoidance, metastasis, and resistance to therapy. The analysis of methylome has revealed patterns of global methylation, which regulate important signaling pathways involved in therapy resistance in different cancer types, such as breast, colon, and lung cancer, among other solid tumors. This analysis has provided gene-expression signatures of methylated region-specific DNA that can be used to predict the treatment outcome in response to anti-cancer therapy. Additionally, changes in cancer methylome have been associated with the acquisition of drug resistance. We also review treatments with demethylating agents that, in combination with standard therapies, seem to be encouraging, as tumors that are in early stages can be successfully treated. On the other hand, tumors that are in advanced stages can be treated with these combination schemes, which could sensitize tumor cells that are resistant to the therapy. We propose that rational strategies, which combine specific demethylating agents with conventional treatment, may improve overall survival in cancer patients.

Clinicopathological Significance and Diagnostic Value of DLEC1 Hypermethylation in Lung Cancer: A Meta-analysis

BACKGROUND

DLEC1 is a tumor-suppressor gene which plays a role in carcinogenesis. The purpose of the current study was to help establish the diagnostic performance of DLEC1 methylation in lung cancer.

METHODS

PubMed, Embase, CNKI, and Wanfang databases were searched to obtain eligible studies. The pooled odds ratios (ORs) and 95% confidence intervals (CIs) were calculated to estimate the strength of the associations. The diagnostic value was assessed by the summary receiver operating characteristics test.

RESULTS

A total of 7 articles, with 8 studies that included 673 lung cancer and 581 control samples, were collected in this meta-analysis. Our results showed a significant association of DLEC1 hypermethylation with lung cancer (P < 0.00001, OR = 13.93, 95% CI = 9.44-20.55). The frequency of DLEC1 methylation was significantly higher in squamous cell carcinoma (SCC) than adenocarcinoma (AC). Moreover, DLEC1 was more frequently methylated in patients with lung cancer aged 60 years or over, patients with lymphatic metastasis, or patients with stage III/IV lung cancer. In addition, there was a sensitivity value of 0.90 (95% CI = 0.86-0.93) and a specificity value of 0.60 (95% CI = 0.56-0.63), a pooled positive-likelihood ratio (PLR) of 2.27 (95% CI = 2.08-2.48), a pooled negative-likelihood ratio (NLR) of 0.17 (95% CI = 0.12-0.23), a diagnostic odds ratio (DOR) of 14.72 (10.09-21) and an area under the curve (AUC) of 0.8146 using DLEC1 methylation in the prediction of lung cancer risk.

CONCLUSION

This meta-analysis confirms that DLEC1 methylation is a promising biomarker for lung cancer.

A systematic review and meta-analysis approach on diagnostic value of MLH1 promoter methylation for head and neck squamous cell carcinoma

BACKGROUND

Head and neck squamous cell carcinoma (HNSCC) is the leading histological type among head and neck cancers. Several studies have explored an association between aberrant methylation of MutL homolog-1 (MLH1) promoter and HNSCC risk. We aimed to explore the associations between MLH1 promoter methylation and HNSCC by using a meta-analysis.

METHODS

Systematic literature search was conducted among PubMed, Google Scholar, Web of Science, and China National Knowledge Infrastructure, and Wanfang databases to retrieve relevant articles published up to June 30, 2018. A total of 12 studies were included in this meta-analysis (including 717 HNSCC and 609 controls).

RESULTS

The results demonstrated that MLH1 promoter methylation was notably higher in patients with HNSCC than in controls (odds ratios [ORs] = 2.52, 95% confidence intervals [CIs] = 1.33-4.79). Besides, MLH1 promoter methylation was not associated with tumor stage, lymph node status, smoking behavior, age, clinical stage, gender, and differentiation grade (all P > .05). The pooled sensitivity and specificity rates of MLH1 methylation for HNSCC were 0.23 (95% CI = 0.12-0.38) and 0.95 (95% CI, 0.82-0.99), respectively. The area under the receiver operating characteristic (ROC) curve was presented as 0.64 (95% CI = 0.60-0.68).

CONCLUSION

The results of this meta-analysis suggested that hypermethylation of MLH1 promoter was associated with HNSCC. Methylated MLH1 could be a potential diagnostic biomarker for diagnose of HNSCC.

The gene mutations and subtelomeric DNA methylation in immunodeficiency, centromeric instability and facial anomalies syndrome

Immunodeficiency, centromeric instability and facial anomalies syndrome (ICF) is a rare autosomal recessive disorder, which is characteristic of a severe impairment of immunity. In the genetic aspect, ICF is featured with mutations primarily located in the specific genes (DNMT3B for ICF1, ZBTB24 for ICF2, CDCA7 for ICF3, and HELLS for ICF4). The subtelomeric region is defined as 500 kb at the terminal of each autosomal arm. And subtelomeric DNA fragments can partially regulate key biological activities, including chromosome movement and localization in the nucleus. In this review, we updated and summarized gene mutations in ICF based on the previous review. In addition, we focused on the correlation between subtelomeric DNA methylation and ICF. The relationship between subtelomeric methylation and telomere length in ICF was also summarized.

Impact of Heat Shock Protein 90 Inhibition on the Proteomic Profile of Lung Adenocarcinoma as Measured by Two-Dimensional Electrophoresis Coupled with Mass Spectrometry

Heat shock protein 90 (HSP90) is an important chaperone in lung adenocarcinoma, with relevant protein drivers such as EGFR (epidermal growth factor receptor) and EML4-ALK (echinoderm microtubule-associated protein-like protein4 fused to anaplastic lymphoma kinase) depending on it for their correct function, therefore HSP90 inhibitors show promise as potential treatments for lung adenocarcinoma. To study responses to its inhibition, HSP90 was pharmacologically interrupted by geldanamycin and resorcinol derivatives or with combined inhibition of HSP90 plus HSP70 in lung adenocarcinoma cell lines. Two-dimensional electrophoresis was performed to identify proteomic profiles associated with inhibition which will help to understand the biological basis for the responses. HSP90 inhibition resulted in altered protein profiles that differed according the treatment condition studied. Results revealed 254 differentially expressed proteins after treatments, among which, eukaryotic translation initiation factor3 subunit I (eIF3i) and citrate synthase demonstrated their potential role as response biomarkers. The differentially expressed proteins also enabled signalling pathways involved in responses to be identified; these included apoptosis, serine-glycine biosynthesis and tricarboxylic acid cycle. The proteomic profiles identified here contribute to an improved understanding of HSP90 inhibition and open possibilities for the detection of potential response biomarkers which will be essential to maximize treatment efficacy in lung adenocarcinoma.

Aberrant methylation of mutL homolog 1 is associated with increased risk of non-small cell lung cancer

BACKGROUND

Non-small cell lung cancer (NSCLC) is a common malignant tumor. DNA hypermethylation in the promoter region has been served as a potential molecular marker for several tumors. The goal of the current study was to assess the diagnostic ability of mutL homolog 1 (MLH1) promoter methylation in NSCLC.

METHODS

A total of 111 NSCLC patients' paired tissue samples were obtained to explore the association between MLH1 promoter methylation and NSCLC by methylation-specific polymerase chain reaction (MSP) method. Public databases including The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) were used to verify our findings.

RESULTS

Our results showed a significantly higher MLH1 methylation frequency in tumor tissue samples than their paired adjacent tissues (P = .008). ROC curve indicated that MLH1MSP assay was a sensitive but not a specific method in the diagnosis for NSCLC (sensitivity = 0.964, specificity = 0.135, AUC = 0.550). And the association between the methylation level and clinical characteristics has no statistical significance. TCGA cohort evinced a higher methylation probability in tumor group compared with nontumor group (the mean β value: -0.449 [-0.467, -0.437] vs -0.466 [-0.472, -0.437], P = .011), which was consistent with our results. Meanwhile, an inverse correlation between MLH1 methylation and MLH1 expression was detected in TCGA and GEO databases.

CONCLUSIONS

The MSP method for MLH1 methylation was a sensitive but not a specific diagnostic method for NSCLC.