MicroRNA inhibitor

A small RNA inhibitor comprising a first binding region and a second binding region;

• the first binding region is located at 5′ end of the small RNA inhibitor, comprising an antisense complementary sequence targeting a 5′ region of a small RNA, which can bind to the 5′ region of the targeted small RNA molecule by base complementation;
• the second binding region is located at 3′ end of the small RNA inhibitor, comprising an antisense complementary sequence targeting a 3′ region of the small RNA, which can bind to the 3′ region of the targeted small RNA molecule by base complementation,
• wherein a length of the small RNA inhibitor sequence is 19-26 nt;
• there is a junction region between the first binding region and the second binding region, the junction region is composed of 0-3 nucleotide residues, the junction region and the first binding region and the second binding region are single-stranded;
• the small RNA inhibitor can bind the small RNA molecule, thereby inhibiting biological functions of the small RNA molecule, the type of small RNA molecule is selected from the group consisting of:
• miRNA, siRNA, and piRNA;
• and
• a length of nucleotide contained in the first binding region is N1, a length of nucleotide contained in the second binding region is N2, a length of nucleotide in the 5′ region of the small RNA molecule is N1′, a length of nucleotide in the 3′ region of the small RNA is N2′, a length of total nucleotides of the small RNA is N0, and the 5′ region of the small RNA molecule does not overlap with the 3′ region of the small RNA molecule,
• wherein N1′+N2′=N0;
• 0.3<N1′/N0<0.7;
• 0.3<N2′/N0<0.7;
• N1:N0=(0.3˜0.7):1;
• and
• N2:N0=(0.3˜0.7):1;
• wherein a ratio of the length N1 of the first binding region and the length N2 of the second binding region to the total nucleotide length N0 of the small RNA molecule is N1:N0=(0.4˜0.6):
• 1, N2:N0=(0.4˜0.6):
• 1;
• bases of the first binding region or the second binding region are completely complementary binded to all bases of the 5′ region or the 3′ region of the small RNA molecule.