Introduction and objective:
Breast cancer (BC) remains the most common malignant tumour among females. Dysregulated microRNAs (miRNAs) are key regulators in carcinogenesis, and single nucleotide polymorphisms (SNPs) represent their most prevalent genetic alterations. The aim of the study is to investigate the influence of rs1264440 on miR-877-3p expression and its subsequent effects on BC cell proliferation and migration.

Material and methods:
Both 160 female BC patients and 160 healthy control (HC) subjects in Maternity and Child Care Center of Qinhuangdao, China, were selected as case and control groups, respectively. Genotyping for the SNP rs1264440 was performed using a TaqMan probe-based RT-qPCR assay. The Cell Counting Kit-8 (CCK-8) assay was used to determine cell viability. Analysis of cell migration and invasion was conducted by transwell assays.

Results:
rs1264440 AA genotype (P = 0.006, OR = 0.308, 95% CI=0.129–0.739), A allele (P = 0.003, OR = 0.586, 95% CI = 0.413–0.832) significantly correlated with BC susceptibility. The rs1264440 AA genotype was associated with decreased miR-877-3p levels. High miR-877-3p level could distinguish BC patients from controls with an area under the curve (AUC) of 0.854 (sensitivity=73.13%, specificity=84.38%). Inhibition of miR-877-3p suppressed the proliferative, migratory, and invasive capacities of BC cells in vitro.

Conclusions:
The miR-877-3p rs1264440 is a risk predictor for BC, being implicated in miR-877-3p dysregulation and the promotion of cell viability and motility.