Up-regulated lncRNA AFAP1-AS1 indicates a poor prognosis and promotes carcinogenesis of breast cancer

Background: Long noncoding RNAs (lncRNAs) have been reported to play crucial roles in breast cancer. This study aimed to determine the clinical significance and biological functions of lncRNA AFAP1-AS1 in breast cancer.

Methods: The expression of AFAP1-AS1 in breast cancer tissue and adjacent normal tissue from 160 patients and breast cancer cell lines were determined by qRT-PCR. The clinical characteristics of patients were collected to analyse the correlation between AFAP1-AS1 expression and malignancy status. Kaplan-Meier and Cox proportional hazards model were used to analyze whether AFAP1-AS1 expression impacted prognosis. To assess the effect of AFAP1-AS1 on MCF-7 cells proliferation, cell viability, EdU incorporation and colony formation assays were conducted after AFAP1-AS1 knockdown by siRNA. The apoptosis was detected by Caspase-3 activity, cell cycle analysis, Bcl-2 and Bax protein expression. Wound scratch assay and EMT-related protein expression (E-cadherin, N-cadherin and Vimentin) were conducted to evaluate the metastasis ability. To further determine the effect of AFAP1-AS1 on AFAP1, the mRNA and protein expression of AFAP1 and subsequent actin filament integrity were measured after AFAP1-AS1 knockdown.

Results: The expression of AFAP1-AS1 was up-regulated in human breast cancer tissue and associated with malignancy status, high expression of AFAP1-AS1 had a poor prognosis in breast cancer patients. AFAP1-AS1 expression was up-regulated in 4 breast cancer cell lines (MCF-7, SK-RB-3, MDA-MB-231and MDA-MB-468) compared with normal breast cell line HBL-100. MCF-7, the most up-regulation cancer cell, was used for following studies. AFAP1-AS1 knockdown can inhibit the proliferation, metastasis and promote apoptosis of MCF-7. However, the AFAP1 expression and actin filament integrity was not affected after AFAP1-AS1 knockdown.

Conclusion: Up-regulated lncRNA AFAP1-AS1 indicates a poor prognosis in breast cancer patients and regulated the breast cancer cells proliferation, apoptosis and metastasis.