GUARDIN is necessary for preventing chromosome end-to-end fusion through maintaining the expression of telomeric repeat-binding factor 2 (TRF2) by sequestering microRNA-23a.Moreover, GUARDIN also sustains breast cancer 1 (BRCA1) stability by acting as an RNA scaffold to facilitate the heterodimerization of BRCA1 and BRCA1-associated RING domain protein 1 (BARD1).As such, GUARDIN silencing triggered apoptosis and senescence,enhanced cytotoxicity of additional genotoxic stress and inhibited cancer xenograft growth. Thus, GUARDIN may constitute a target for cancer treatment. GUARDIN functions to regulate TRF2 and IRF1 through sequestering miR-23a.