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

Abstract

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.

Keywords: 8q24; cytoband; gastric cancer; genes; single nucleotide polymorphism.

Figure 1.

Top: illustration of the normal gastric mucosa, stomach parts, molecular factors, and carcinogens. Bottom right: diffuse gastric cancer and certain factors that participate in the development of the neoplasia. Bottom left: gastric intestinal cancer, the precancerous chain, and certain factors that influence the development of neoplasia. CNA, copy number alterations.

Figure 2.

The complete chromosome 8 is shown on the left side, the centromeres are shown in green, and of the 40 cytobands, three are highlighted in red as they are most commonly affected in GC. Each affected cytoband has a gray bar with blue rectangles, indicating the affected genes. In the yellow rectangles, the genes and their SNP identified in GC are observed, and in pink, those that present an alteration, such as CNV. GC, gastric cancer; SNP, single nucleotide polymorphism; CNV, copy number variation; NSMCE2, NSE2 (MMS21) homolog, SMC5-SMC6 complex SUMO ligase; PCAT1, prostate cancer associated transcript 1; CASC19, cancer susceptibility 19; CASC8, cancer susceptibility 8; CCAT2, colon cancer associated transcript 2; PRNCR1, prostate cancer associated non-coding RNA 1; POU5F1B, POU class 5 homeobox 1B; PVT1, Pvt1 oncogene; PSCA, prostate stem cell antigen; PTK2, protein tyrosine kinase 2; JRK, jrk helix-turn-helix protein; >, sense; <, antisense.