Recent studies have reported that chemically synthesized small activating RNA (saRNA) targeting the promoter regions of a gene can activate its expression in different cell lines. This technique can be a powerful therapeutic method for diseases caused by complete inactivation or reduced expression of specific genes. E-cadherin is a typical tumor suppressor gene. Loss of E-cadherin mediates the transition from benign lesions to invasive, metastatic cancer. In this study, several 21-nt small double-stranded RNAs (dsRNAs) targeting the promoter regions of human E-cadherin were designed and synthesized and the features of their function were investigated to study the regulatory role of dsRNA on E-cadherin expression. A new saRNA (dsEcad‑661) that can enhance E-cadherin expression by targeting non-coding regulatory regions in gene promoters was identified. Using dsRNA with modified base quantity and cholesterol-conjugated dsRNA, we found the antisense strand may be the guide strand of saRNA in the upregulation of E-cadherin. These findings provide several important pieces of evidence that may improve understanding of the function of saRNA and may promote its development for clinical application.