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Background: Gastric cancer is one of the most significant reasons for cancer-related death. miR-146a is one of the dysregulated factors associated with gastric tumorigenesis. However, deregulation of this microRNA (miRNA) has become controversial. Moreover, the inflammation-mediating role of this miRNA implies that miR-146a might be dysregulated by gastric cancer-related pathogens, such as Helicobacter pylori. However, the dysregulation of miR-146a in H. pylori-infected gastric tumors has not been widely studied. Objectives: We aimed to analyze the expression level of miR-146a in gastric cancer tissues and then to assess any potential association between miR-146a and H. pylori infection and other clinical characteristics. Materials and Methods: miR-146a expression level was quantitatively studied by reverse transcription quantitative polymerase chain reaction, in 144 fresh tissues including 44 normal and 100 gastric cancer samples. Results: A dramatic overexpression of miR-146a was observed in primary gastric tumors. miR-146a showed lower expression in progressed tumors with greater stages and lymph node metastasis. Conclusion: miR-146a is highly expressed in primary gastric tumor independent of H. pylori infection. It is highly expressed in the lower stages and lymph node-negative tumors. It might suggest the importance of upregulation and downregulation of this miRNA in the initiating/promoting and progressive steps of gastric tumorigenesis, respectively.

Context: A number of single nucleotide polymorphisms (SNPs) in ERBB4 gene have been linked to increase the risk of breast cancer. However, no study has been dedicated to analyze the significance of microRNA-related SNP rs1972820, located in ERBB4 3'-untranslated region (UTR), in breast tumors. Aims: Here, we investigated the frequency and association between rs1972820 and breast cancer. Subjects and Methods: The rs1972820 genotypes in 182 samples were collected from 96 healthy people, and 86 breast cancer patients were determined using tetra-primer amplification refractory mutation system-polymerase chain reaction. The frequency of genotypes was analyzed to find the association between rs1972820 and breast cancer risk. Statistical Analysis Used: Conditional logistic regression, odds ratios (ORs), the associated 95% confidence intervals (CIs), and Armitage's test were used in this study. Results: In silico analysis suggested that rs1972820 located in the 3'UTR of ERBB4 gene affects the binding affinity of miR-3144-3p a potential oncomiRNA. Statistical analysis showed a significant association between SNP rs1972820 G allele and reduced breast cancer risk, odds ratio = 0.443 (95% CI: 0.196–0.998). Conclusions: rs1972820 SNP allele is significantly associated with the reduced risk of breast cancer and could be considered as a potential marker for breast cancer predisposition in population of Isfahan.