AbstractBackgroundBreast cancer represents the second most deadly malignancy in women, and long noncoding RNAs (lncRNAs) have crucial functions in its development.ObjectiveTo investigate effects of the promoter ofCDKN1Aantisense DNA damage-activated RNA (PANDAR) on epithelial-mesenchymal transition (EMT) in breast cancer cells and their proliferation.MethodslncRNAs potentially regulating the transcriptional activity of the E-cadherin (E-cad, an epithelial cell marker) gene promoter were screened using a dual-luciferase reporter assay.PANDARwas overexpressed in Michigan cancer foundation 7 (MCF-7) breast cancer cells. E-cad and N-cadherin (N-cad, a mesenchymal cell marker) levels were detected by immunoblotting. Cell viability was assessed using a cell counting kit-8.ResultsPANDARandTCONS00068220/LOC105375819conservatively regulated the promoter activity ofE-cad.PANDARoverexpression in MCF-7 inhibited E-cad expression, but upregulated N-cad. The enhanced expression ofPANDARpromoted cell proliferation.ConclusionPANDARis a key transcriptional repressor ofE-cadand has regulatory effects on the promotion of cell proliferation.PANDARis an oncogene in breast cancer, potentially facilitating the EMT process and promoting cell proliferation.