GC is a multifactorial disorder, in which genetic and environmental interactions serve an important role in the development and progression[23]. Increasing age, gender, lifestyle, dietary regime, environmental factors, and Helicobacter pylori infections are among the known risk factors for stomach cancer[24]. While dietary regime and lifestyle are the most recognized factors, enhanced identification of the genetic risk factors is expected to improve the understanding of the basic molecular events involved in tumorigenesis[25]. Genetic factors, including gene expression profile and cancer biomarkers, such as SNPs, have a crucial role in improving the early diagnosis of GC[26].
Recent studies have demonstrated that a high number of genes and various environmental factors are the causal agents of GC, and the presence of different forms of alleles in gene polymorphisms may promote the development of cancers. In this regard, p73 has been a research focus due to its role as a major tumor suppressor gene[27]. p73 has some functions similar to or independent of p53 and plays a role, particularly in compensation for loss of p53 function, in the regulation of cell cycle, DNA repair, apoptosis, and possibly cell differentiation. In the past decades, almost 146 unique variations were reported (shown in the Biomuta database)[28], while numerous studies probed into the relationship of G4C14-A4T14 polymorphism and cancer genomics. G4A (rs2273953) and C14T (rs1801173) polymorphisms are located at positions 4 (G to A) and 14 (C to T) of exon 25′-untranslated region, which may influence the initiating AUG codon by constructing a stem loop[29]. In recent years, the G4C14-A4T14 polymorphism of p73 has been identified to be implicated in the tumorigenesis of various cancer types. However, the data from these published case-control studies were not consistent.
Yang et al.[30] and Niwa et al.[31] reported that G4C14-A4T14 polymorphism is not associated with the susceptibility of cervical cancer in Uighur and Japanese population, respectively. However, Craveiro et al.[32] and Feng et al.[33] revealed that G4C14-A4T14 polymorphism leads to an increasing risk of cervical cancer. Hamajima et al. [34] demonstrated no significant differences in the genotype frequencies among the enrolled cases and controls in their study of colorectal cancer. On the contrary, Lee et al.[35] reported that GC/AT and AT/AT genotypes are significantly associated with the risk of colorectal cancer in Korean population. Arfaoui et al.[36] also uncovered no remarkable differences in genotype frequencies in cancers and controls, but they found that AT/AT genotype may cause poor prognosis of colorectal cancer. Hu et al.[37] indicated that AT/AT and GC/AT variants are associated with a remarkable decrease in the risk of lung cancer. Li et al.[38] suggested that the AT/AT and GC/AT genotypes are related, with a statistically significantly increased risk of lung cancer. However, Choi et al.[39] revealed that the G4C14-A4T14 polymorphism of p73 does not affect the susceptibility of lung cancer in Korean population. Zheng et al.[9] found that the rs1801173 C > T SNPs of p73 are associated with increased risk of ESCC. However, p73 gene polymorphism and GC susceptibility have not been reported yet. Therefore, the rs1801173 C/T polymorphism of p73 merits further functional study to elucidate the etiology of SNP and GC.
In the present study, no statistically significant association was found between p73 rs1801173 C > T gene polymorphism and the risk of GC in a Chinese Han Population. Although the C mutant allele frequency was higher in patients with GC than in controls, the difference was not statistically significant. However, the frequency of smoking factors in the case group was 34.49%, higher than that in the control group by 27.29%, and the difference was statistically significant. This result showed that smoking is related to the occurrence and development of GC. Li et al.[40] studied the connection between p73 G4C14-to-A4T14 polymorphism and the risk of lung cancer. They found that the increased risk associated with the combined p73 GC/AT + AT/AT genotype in younger (≤ 50 years) subjects and light (compared with heavy) smokers suggested an early onset and lower levels of exposure characteristic of genetic susceptibility. They also observed a significantly higher risk in men than in women, particularly among smokers. However, the interaction between smoking and p73 polymorphism was only borderline significant, which warrants additional investigations with larger sample sizes.
This case-control study had several limitations. First, because the patients and controls were enrolled from hospitals, inherent bias may have resulted in spurious findings. Second, the polymorphisms may not provide a comprehensive view of p73 genetic variability. Fine-mapping studies are required. Third, the statistical power was limited because of the moderate sample size and the absence of a validation cohort. In addition, considering that gene–gene interaction and gene–environment interaction play an important role in the pathogenesis of many diseases, especially chronic diseases, p73 gene polymorphism may interact with other gene polymorphisms or environmental factors, thereby affecting the incidence of GC in the population. H. pylori infections, lifestyle, and dietary regime were not investigated. Other limitations included small sample size and sampling of individuals of the same geographical region and race. Therefore, further studies considering different geographical locations and races and a larger number of participants are necessary to confirm the results of the present study. These results failed to indicate an association between p73 rs1801173 polymorphism and risk of GC. Tissue-specific biological characterization and replication studies with larger populations are also required to confirm these findings.