Abstract: Objective:To investigate the expression of long-chain non-coding HOX transcript antisense RNA(HOTAIR) in breast cancer tissues and cells,and effects of arsenic trioxide(As2O3) on its expression.Methods:The expressions of long-chain non-coding HOTAIR mRNA in breast carcer tissue and pericarcinomatous tissue were detected using real-time fluorescence quantitative PCR.Breast cancer cell lines with high expression HOTAIR was screened,the effect of As2O3 on the expression of HOTAIR mRNA was detected.The expressions of HOTAIR between breast cancer tissue,pericarcinomatous tissue and breast cancer cell lines were compared.The HOTAIR expression in MCF-7 cells treated with As2O3 was detected.Results:The expression quantity of HOTAIR mRNA in breast cancer was 0.011?0.005,no expression of HOTAIR was found in pericarcinomatous tissue.The HOTAIR mRNA expression was not found in SKBR-3 and MAD-MB-231 cells.The high expression of HOTAIR mRNA(1?0.236) was detected in MCF-7 cells.The expression level of HOTAIR mRNA in MCF-7 cells treated with As2O3 was significantly lower than that in blank group(PConclusions:The HOTAIR expression is associated with the incidence of breast cancer,and As2O3 can inhibit its expression.