Infection with Helicobacter pylori is associated with the development of gastric cancer. Although the prevalence of gastric cancer has declined throughout years due to improvement in early screening strategy, mortality due to gastric cancer has not changed. Incidence and mortality due to gastric cancer are higher in developing countries as compared to developed countries. Diagnosis and prognosis of gastric cancer are still poor with patients usually diagnosed with cancer at an advanced stage. Eradication of H. pylori is pertinent for the prevention of gastric cancer. However, the rise in antimicrobial resistance among H. pylori isolates has complicated the prevention strategy. H. pylori express multiple virulence factors for survival in the hostile acid gastric environment. The expression of oncogenic protein cytotoxin-associated gene A (CagA), vacuolating cytotoxin A (VacA), and outer inflammatory protein is essential for H. pylori to exert pathogenesis towards the host. Interestingly, <3% of H. pylori-infected subjects develop gastric cancer, suggesting a unique way of interaction between the host's immune response and H. pylori virulence factors. This article is aimed to review the epidemiology and role of H. pylori in gastric carcinogenesis. A better understanding of the interaction between H. pylori virulence factors and host is required for better gastric cancer prevention.
Orang Asli are the oldest inhabitants in Peninsular Malaysia that forms as a national minority while the Malays are the majority. The study aimed to screen the mitochondrial genomes of the Orang Asli and the Malays to discover the disease-associated variants. A total of 99 Orang Asli from six tribes (Bateq, Cheq Wong, Orang Kanaq, Kensiu, Lanoh, and Semai) were recruited. Mitochondrial genome sequencing was conducted using a next-generation sequencing platform. Furthermore, we retrieved mitochondrial DNA sequences from the Malays for comparison. The clinical significance, pathogenicity prediction and frequency of variants were determined using online tools. Variants associated with mitochondrial diseases were detected in the 2 populations. A high frequency of variants associated with mitochondrial diseases, breast cancer, prostate cancer, and cervical cancer were detected in the Orang Asli and modern Malays. As medicine evolves to adopt prediction and prevention of diseases, this study highlights the need for intervention to adopt genomics medicine to strategise better healthcare management as a way forward for Precision Health.
The multiracial population in Malaysia has lived together for almost a century, however, the risk of gastric cancer among them varies. This study aimed to determine the distribution of different gastric adenocarcinoma subtypes and Helicobacter pylori infection status among gastric adenocarcinoma patients. Patients with gastric adenocarcinoma were enrolled from November 2013 to June 2015. Blood samples were collected for detection of H. pylori using ELISA method. Gastric adenocarcinoma cases were more prevalent in the Chinese (52.8%), followed by the Malays (41.7%) and least prevalent in the Indians (5.6%). Gastric adenocarcinoma located in the cardia was significantly more prevalent in the Malays (66.7%) compared to the Chinese (26.3%), whereas non-cardia cancer was diagnosed more in the Chinese (73.7%) compared to the Malays (33.3%) [P = 0.019; OR = 5.6, 95 CI: 1.27 to 24.64]. The Malays also had significantly higher prevalence of gastric tumour located at the cardia or fundus than other gastric sites compared to the Chinese (P = 0.002; OR: 11.2, 95% CI: 2.2 to 56.9). Among the cardia gastric cancer patients, 55.6% of the Malays showed intestinal histological subtype, whereas all the Chinese had the diffuse subtype. More than half of the patients (55.3%) with gastric adenocarcinoma were positive for H. pylori infection and among them, 66.7% were Chinese patients. The risk of gastric adenocarcinoma in our population is different among ethnicities. Further studies on host factors are needed as it might play an important role in gastric cancer susceptibility in our population.
Comprehensive immunophenotyping cluster of differentiation (CD) antigens in gastric adenocarcinoma, specifically between Helicobacter pylori-infected and -uninfected gastric cancer patients by using DotScan(™) antibody microarray has not been conducted. Current immunophenotyping techniques include flow cytometry and immunohistochemistry are limited to the use of few antibodies for parallel examination. We used DotScan(™) antibody microarray consisting 144 CD antibodies to determine the distribution of CD antigens in gastric adenocarcinoma cells and to elucidate the effect of H. pylori infection toward CD antigen expression in gastric cancer.
Chloramphenicol (CAP) and cyclo-(L-Val-L-Pro) were previously isolated from Streptomyces sp., SUK 25 which exhibited a high potency against methicillin-resistant Staphylococcus aureus (MRSA). This study aimed to profile gene expression of MRSA treated with CAP and cyclo-(L-Val-L-Pro) compounds using DNA microarray. Treatment of MRSA with CAP resulted in upregulation of genes involved in protein synthesis, suggesting the coping mechanism of MRSA due to the inhibition of protein synthesis effect from CAP. Most upregulated genes in cyclo-(L-Val-L-Pro) were putative genes with unknown functions. Interestingly, genes encoding ribosomal proteins, cell membrane synthesis, DNA metabolism, citric acid cycle and virulence were downregulated in MRSA treated with cyclo-(L-Val-L-Pro) compound, suggesting the efficacy of this compound in targeting multiple biological pathways. Contrary to CAP, with only a single target, cyclo-(L-Val-L-Pro) isolated from this study had multiple antimicrobial targets that can delay antibiotic resistance and hence is a potential antimicrobial agent of MRSA.