Abstract: Objective To explore the expression of long non-coding RNA urothelial cancer-associated 1 (lncRNA UCA1) in breast cancer cells and its effect on the proliferation of breast cancer cells. Methods The expression levels of lncRNA UCA1 were analyzed in breast cell lines of BT-459, SKBR3, MCF-7, T47D and MDA-MB231 through quantitative reverse-transcription polymerase chain reaction (qRT-PCR) analysis. The lentivirus UCA1 was transfected into breast cancer cells. The cell proliferation ability and cell cycle distribution were detected by flow cytometry and MTT assay respectively. The expression of WNT6 in WNT signaling was examined by qRT-PCR and Western blot. Results The expression levels of lncRNA UCA1 were higher in breast cancer cell lines compared with normal breast epithelial cell (P<0.05). Overexpression of UCA1 significantly enhanced cell proliferation and cell cycle progression (P<0.05). And both gene and protein level of WNT6 were improved after overexpression of UCA1 (P<0.05). Conclusions lncRNA UCA1 is highly expressed in breast cancer cell lines. Overexpression of UCA1 promotes cell proliferation, which may be related to WNT signaling pathway. This study provides some experimental basis for the clinical application of lncRNA.