DNA repair dysfunction in gastrointestinal tract cancers

Biomechanistic insights into the roles of oxidative stress in generating complex neurological disorders

Neurological diseases like Alzheimer's disease, epilepsy, parkinsonism, depression, Huntington's disease and amyotrophic lateral sclerosis prevailing globally are considered to be deeply influenced by oxidative stress-based changes in the biochemical settings of the organs. The excess oxygen concentration triggers the production of reactive oxygen species, and even the intrinsic antioxidant enzyme system, i.e. SOD, CAT and GSHPx, fails to manage their levels and keep them under desirable limits. This consequently leads to oxidation of protein, lipids and nucleic acids in the brain resulting in apoptosis, proteopathy, proteasomes and mitochondrion dysfunction, glial cell activation as well as neuroinflammation. The present exploration deals with the evidence-based mechanism of oxidative stress towards development of key neurological diseases along with the involved biomechanistics and biomaterials.

Diagnostic, Predictive, Prognostic, and Therapeutic Molecular Biomarkers in Third Millennium: A Breakthrough in Gastric Cancer

Introduction

Gastric cancer is the fifth most common cancer and the third cause of cancer death. The clinical outcomes of the patients are still not encouraging with a low rate of 5 years' survival. Often the disease is diagnosed at advanced stages and this obviously negatively affects patients outcomes. A deep understanding of molecular basis of gastric cancer can lead to the identification of diagnostic, predictive, prognostic, and therapeutic biomarkers.

Main Body

This paper aims to give a global view on the molecular classification and mechanisms involved in the development of the tumour and on the biomarkers for gastric cancer. We discuss the role of E-cadherin, HER2, fibroblast growth factor receptor (FGFR), MET, human epidermal growth factor receptor (EGFR), hepatocyte growth factor receptor (HGFR), mammalian target of rapamycin (mTOR), microsatellite instability (MSI), PD-L1, and TP53. We have also considered in this manuscript new emerging biomarkers as matrix metalloproteases (MMPs), microRNAs, and long noncoding RNAs (lncRNAs).

Conclusions

Identifying and validating diagnostic, prognostic, predictive, and therapeutic biomarkers will have a huge impact on patients outcomes as they will allow early detection of tumours and also guide the choice of a targeted therapy based on specific molecular features of the cancer.

Predictive biomarkers along gastric cancer pathogenetic pathways

INTRODUCTION

Gastric cancer is the second leading cause of cancer all over the world. Unfortunately, several gastric cancers are diagnosed in an advanced stage and chemotherapy and/or target therapies remain the only options to treat patients. Areas covered: Herein we evaluate the new molecular proposal of gastric cancer classification, offering the possibility to recognize different pathogenetic mechanisms and molecular biomarkers potentially useful for target therapies. Expert commentary: The possibility of introducing new specific tests for identification of molecular biomarkers critical for targeted therapies response represents the new frontier in the selection of gastric cancer patients to improve their survival. Besides HER2, already used in clinical settings as a target biomarker for biological therapy in gastric cancer patients with tissue cancer cells overexpressing HER2, other promising target biomarkers which are deregulated in gastric cancer, such as MET and FGFR, could be identified in tissue and then used for therapeutic purposes. In addition immunotherapy represents the most promising possibility of advanced gastric cancer treatment. In particular, as in other solid tumors, PD-1/PDL1 pathway has emerged in several clinical trials as an interesting therapeutic target.

ARID1A expression in gastric adenocarcinoma: Clinicopathological significance and correlation with DNA mismatch repair status

AIM: To analyze the mismatch repair (MMR) status and the ARID1A expression as well as their clinicopathological significance in gastric adenocarcinomas.

METHODS: We examined the expressions of MMR proteins and ARID1A by immunohistochemistry in consecutive 489 primary gastric adenocarcinomas. The results were further correlated with clinicopathological variables.

RESULTS: The loss of any MMR protein expression, indicative of MMR deficiency, was observed in 38 cases (7.8%) and was significantly associated with an older age (68.6 ± 9.2 vs 60.4 ± 11.7, P < 0.001), a female sex (55.3% vs 31.3%, P = 0.004), an antral location (44.7% vs 25.7%, P = 0.021), and a differentiated histology (57.9% vs 39.7%, P = 0.023). Abnormal ARID1A expression, including reduced or loss of ARID1A expression, was observed in 109 cases (22.3%) and was significantly correlated with lymphatic invasion (80.7% vs 69.5%, P = 0.022) and lymph node metastasis (83.5% vs 73.7%, P = 0.042). The tumors with abnormal ARID1A expression more frequently indicated MMR deficiency (47.4% vs 20.2%, P < 0.001). A multivariate analysis identified abnormal ARID1A expression as an independent poor prognostic factor (HR = 1.36, 95%CI: 1.01-1.84; P = 0.040).

CONCLUSION: Our observations suggest that the AIRD1A inactivation is associated with lymphatic invasion, lymph node metastasis, poor prognosis, and MMR deficiency in gastric adenocarcinomas.

DNA damage and neurotoxicity of chronic alcohol abuse

Chronic alcohol abuse results in a variety of pathological effects including damage to the brain. The causes of alcohol-induced brain pathology are presently unclear. Several mechanisms of pathogenicity of chronic alcoholism have been proposed, including accumulation of DNA damage in the absence of repair, resulting in genomic instability and death of neurons. Genomic instability is a unified genetic mechanism leading to a variety of neurodegenerative disorders. Ethanol also likely interacts with various metabolic pathways, including one-carbon metabolism (OCM). OCM is critical for the synthesis of DNA precursors, essential for DNA repair, and as a methyl donor for various methylation events, including DNA methylation. Both DNA repair and DNA methylation are critical for maintaining genomic stability. In this review, we outline the role of DNA damage and DNA repair dysfunction in chronic alcohol-induced neurodegeneration.

Pediatric duodenal cancer and biallelic mismatch repair gene mutations

Gastrointestinal malignancies are extremely rare in the pediatric population, and duodenal cancers represent an even more unusual entity. Intestinal cancers in young adults and children have been observed to be associated with functional deficiencies of the mismatch repair (MMR) system causing a cancer-predisposition syndrome. We report the case of a 16-year-old female with duodenal adenocarcinoma and past history of medulloblastoma found to have a novel germline bialleleic truncating mutation (c.[949C>T]+[949C>T]) of the PMS2 gene.