Provided is a polynucleotide including, from the 3′ terminus of the polynucleotide to the 5′ terminus of the polynucleotide, a first region including a nucleotide sequence complementary to a nucleotide sequence of a portion of a target nucleic acid; a second region including a nucleotide sequence identical to a nucleotide sequence of a portion of the target nucleic acid; and a third region including a nucleotide sequence that self-hybridizes to form a stem-loop structure, and compositions, kits, and methods related thereto.