Introduction: MicroRNAs (miRNAs) are small ribonucleic acids that modulate the expression of downstream target genes. There is considerable evidence of their involvement in many malignancies, such as oesophageal and gastric. We hypothesised altered expressions of pri-miR-124-1 rs531564 and STAT3 rs1053023 polymorphisms in gastric cancer. Materials and methods: Genomic DNA was extracted from peripheral blood of 250 patients with gastric cancer and 310 healthy individuals. The RFLP method was applied for determination of pri-miR-124 polymorphism and the AS-PCR method for STAT3 polymorphism. Results: The distribution of rs531564 genotypes in cases and controls was different: the G allele carriers had a reduced gastric cancer risk (OR = 0.62; 95%CI = 0.49–0.80, P = 0.0002). Presence of the minor allele of STAT3 (rs1053023) was linked with higher risk of gastric cancer (OR = 2.29; 95% CI = 1.79–2.93, P < 0.0001). Compared with the most frequent haplotype C-G [the SNP order was pri-miR-124-1 (rs531564) and STAT3 (rs1053023)] in controls, C-A haplotype was associated with a significantly increased risk of gastric cancer (OR = 2.28; 95%CI = 1.64–3.09, P < 0.0001). Conclusion: There is a strong link between pri-miR-124-1 rs531564 and STAT3 rs1053023 and gastric cancer that may be pathogenic, and so worthy of further investigation.

Background: Breast cancer (BC) is one of the main causes of cancer-related death in women worldwide. It is necessary to find methods for prognosis and early detection of BC. MicroRNAs inhibit the expression of special target genes at the post-transcriptional stage and have a fundamental role in various cancers. They function as oncogenes or tumor suppressors. MiR-125a- 5p acts as a tumor suppressor in some cancers through a signal transducer and activator of transcription 3 (STAT3) suppression. STAT3 is activated in response to cytokines and growth factors, affecting the transcription of target genes. Objective: We examined the association between miR-125a-5p and STAT3 expression levels in breast cancer patients for the first time through a case-control study on an Iranian population. Methods: Total RNAs were extracted from breast cancer and healthy tissues using TRIzol Reagent. Complementary DNA synthesis was performed, and Real-time PCR was done using miR-125a and STAT3-specific primers. GAPDH and U48 genes were used as internal controls. Statistical analysis of the results was conducted by SPSS v.19.0 software. Results: We obtained a significant association between miR-125a-5p down-regulation and breast cancer disease (0.4333 in patients vs. 1.656 in controls, p-value = 0.009). STAT3 expression was significantly up-regulated in BC samples relative to healthy subjects (1.324 vs. 0.6557, respectively) and p-value <0.0001. Conclusion: We investigated that decreased miR-125a-5p expression levels were significantly associated with increased STAT3 expression in BC tissues. Therefore, the expression changes of miR- 125a-5p can be an important potential biomarker for early diagnosis of breast cancer. Also, the miRNA molecule may have serious therapeutic potential.

(2019). Relationship of the expression of circulating hsa-miR-125a-3p and hsa-miR-125b with breast cancer. British Journal of Biomedical Science. Ahead of Print.