LncRNA ASBEL has been identified as an anti-sense transcript of BTG3 (B cell translocation gene 3) gene, which encodes an anti-proliferation protein. Remarkable down-regulation of BTG3 has been reported in triple-negative breast cancer (TNBC). In the present study, a number of single-stranded modified anti-sense DNA oligonucleotides (antago) were designed, synthesized and screened for specific lncRNA ASBEL knockdown. We showed here that anti-ASBEL antago played a significant tumor suppressive role in TNBC by effective down-regulation of lncRNA ASBEL, which in turn led to increased BTG3 expression. The obtained data suggest lncRNA ASBEL as a novel therapeutic target in TNBC. antago3 has a great potential to be an useful therapeutic tool for TNBC treatment through targeting lncRNA ASBEL-related pathway.