The landscape of 8q24 cytoband in gastric cancer (Review)

Worldwide, gastric cancer (GC) is estimated to be the fifth most common type of cancer type in both sexes, ranking sixth for new cases, with >640,850 cases per year, and fourth in terms of mortality rate. Cancer presents numerical and structural alterations in chromosomes, often through gains and losses of regions. In GC, there are multiple genetic alterations, in which those located in cytoband 8q24 have been frequently described; essential genes are present in this cytoband, regulating the homeostasis of crucial biological processes, such as the MYC gene, which induces expression of selective genes to promote cell growth and proliferation. Conversely, DNA sequence variations can also occur when a single nucleotide in the genome sequence is altered, and this is termed a single nucleotide polymorphism (SNP). These alterations, which can serve as a biological marker, are present in at least 1% of the population and assist in identifying genes associated with GC. In the present review, 12 genes present in cytoband 8q24 related to GC (NSMCE2, PCAT1, CASC19, CASC8, CCAT2, PRNCR1, POU5F1B, PSCA, JRK, MYC, PVT1 and PTK2) are discussed. The PSCA gene was cited more frequently than others; it has four known SNPs associated with GC (rs2978980, rs2294008, rs2976392 and rs9297976). Thus, these SNPs should be further studied in different populations to determine their risk value in patients with GC.

Copy number alterations and epithelial‑mesenchymal transition genes in diffuse and intestinal gastric cancers in Mexican patients

Gastric cancer (GC) is a common malignancy with the highest mortality rate among diseases of the digestive system, worldwide. The present study of GC alterations is crucial to the understanding of tumor biology and the establishment of important aspects of cancer prognosis and treatment response. In the present study, DNA from Mexican patients with diffuse GC (DGC), intestinal GC (IGC) or non‑atrophic gastritis (NAG; control) was purified and whole‑genome analysis was performed with high‑density arrays. Shared and unique copy number alterations (CNA) were identified between the different tissues involving key genes and signaling pathways associated with cancer. This led to the molecular distinction and identification of the most relevant molecular functions to be identified. A more detailed bioinformatics analysis of epithelial‑mesenchymal transition (EMT) genes revealed that the altered network associated with chromosomal alterations included 11 genes that were shared between DGC, IGC and NAG, as well as 19 DGC‑ and 7 IGC‑exclusive genes. Furthermore, the main molecular functions included adhesion, angiogenesis, migration, metastasis, morphogenesis, proliferation and survival. The present study provided the first whole‑genome high‑density array analysis in Mexican patients with GC and revealed shared and exclusive CNA‑associated genes in DGC and IGC. In addition, a bioinformatics‑predicted network was generated, focusing on CNA‑altered genes associated with EMT and the hallmarks of cancer, as well as precancerous alterations that may lead to GC. Molecular signatures of diffuse and intestinal GC, predicted bioinformatically, involve common and distinct CNA‑EMT genes related to the hallmarks of cancer that are potential candidates for screening biomarkers of GC, including early stages.

Circulating microRNAs and their role in the immune response in triple-negative breast cancer

Breast cancer (BC) is the most common type of cancer in women worldwide, and despite advances in treatments, its incidence and mortality are increasing. Therefore, it is necessary to develop new, non-invasive tests that provide more accurate diagnosis and prognosis in a timely manner. A promising approach is measuring the presence of biomarkers to detect tumors at various stages and determine their specific characteristics, thus allowing for more personalized treatment. MicroRNAs (miRNAs) serve a role in gene expression, primarily by interacting with messenger RNAs, and may be potential biomarkers for detecting cancer. They are detectable in tissues and blood, including plasma and/or serum, are stable and often tumor specific. Also, different miRNAs are associated with specific BC molecular subtypes. Triple-negative BC (TNBC) is a type of BC in which the primary targets for hormonal therapy are absent. It is an aggressive phenotype, which frequently metastasizes and is associated with an unfavorable prognosis. The present review focuses on circulating miRNAs in patients with TNBC, with an emphasis on their interaction with the immune response checkpoint genes PD-1, PD-L1 and CTLA4. Modulation and response of the immune system are of interest in cancer treatment due to the success of immunotherapy in the treatment of various neoplasms. Based on the findings of this literature review and the in silico analysis performed as part of this review, it is concluded that circulating hsa-miR-195 and hsa-miR-155 in TNBC interact with checkpoint genes involved in the immune response. Further analysis of the expression of these circulating miRNAs and their association with prognosis in patients with TNBC treated with immunotherapy should be assessed to evaluate their possible use as non-invasive predictive biomarkers. In addition, functional studies to analyze biologically relevant targets in the development and prognosis of TNBC, which could be therapeutic targets, are also recommended.

A proposed method for the relative quantification of levels of circulating microRNAs in the plasma of gastric cancer patients

Gastric cancer (GC) is the fifth most common type of malignancy and the third leading cause of cancer-associated mortality worldwide. It is necessary to identify novel methods aimed at improving the early diagnosis and treatment of GC. MicroRNA expression profiles in the plasma of patients with GC have demonstrated a potential use in the opportune diagnosis of this neoplasm. However, there are currently no standardized targets for use in the normalization of microRNA Cq values for different neoplasms. The present study tested two normalization approaches while analyzing plasma derived from patients with GC and non-atrophic gastritis. The first method utilized a panel of small nucleolar RNAs (snoRNAs) and a small nuclear RNA (snRNA) provided by a commercial array. The second normalization approach involved the use of hsa-miR-18a-5p and hsa-miR-29a-3p, which were identified by a stability analysis of the samples being tested. The results revealed that the snoRNAs and snRNA were not expressed in all samples tested. Only the stable microRNAs allowed a narrow distribution of the data and enabled the identification of specific downregulation of hsa-miR-200c-3p and hsa-miR-26b-5p in patients with GC. hsa-miR-200c-3p and hsa-miR-26b-5p have been previously linked to cancer, and a Kyoto Encyclopedia of Genes and Genomes analysis demonstrated that these microRNAs were associated with cell adhesion, cell cycle and cancer pathways.

Hepatitis B epidemiology in Latin America

Background

Hepatitis B virus (HBV) is a small DNA-containing virus with 4 genes, C, S, X and P. The S gene codes for the surface antigen (HBsAg), which contains the "a" determinant, the main region for induction of a protective humoral immune response. To compare the genotype and sequence of the "a" determinant between strains isolated from asymptomatic and symptomatic Mexican HBV carriers.

Results

21 asymptomatic (blood donors) and 12 symptomatic (with clinical signs and with >1 year lamivudine treatment) HBV carriers were studied; all patients were positive for the HBsAg in serum. Viral load, genotypes, and subtypes were determined in plasma. A fragment of the S gene including the "a" determinant was PCR amplified and sequenced to determine genotype, subtype and to identify mutations. Mean viral load was 0.7965 × 10⁴ copies/ml in asymptomatic carriers and 2.73 × 10⁶ copies/ml in symptomatic patients. Genotypes H, C, and F were identified in asymptomatic individuals; whereas H was dominant in symptomatic patients. A fragment of 279 bp containing the "a" determinant was amplified from all 33 carriers and sequences aligned with S gene sequences in the GenBank. Mutations identified were Y100N, T126I, Q129H and N146K in the asymptomatic group, and F93I and A128V in the symptomatic group.

Conclusion

Differences in genotype and in mutations in the "a" determinant were found between strains from asymptomatic and symptomatic HBV Mexican carriers.