Abstract: The present invention relates to a pharmaceutical composition for prevention or treatment of cancer, comprising a Runx3 (Runt-related transcription factor 3) protein, a polynucleotide encoding thereof, a vector carrying the polynucleotide or a virus or cell transformed with the vector; and a CDK4 inhibitor or an mTOR inhibitor as an active ingredient. It was confirmed that the binding of Runx3 and BRD2 was maintained for up to 8 hours when the CDK4 inhibitor (PD0332991) was present at the concentration of 11 nM known to be non-toxic to normal cells. It was also confirmed that the binding of Runx3 and BRD2 was maintained for up to 8 hours when the mTOR inhibitor (rapamycin) was present at the concentration of 100 nM known to be non-cytotoxic to normal cells. In addition, it was confirmed that the cancer apoptotic effect was significantly increased when the CDK4 inhibitor or mTOR inhibitor was administered simultaneously with Runx3 than when Runx3 was administered alone to Runx3 deficient cancer cells.

Abstract: In the present invention, it was confirmed that the modified protein in which the 356th serine of Runx3 is substituted with alanine has an increased activity of maintaining the complex with Brd2 by more than 10 times compared to the wild-type Runx3, and the apoptosis effect is improved in various cancer cell lines compared to the wild-type Runx3. Therefore, the modified protein in which the 356th serine of Runx3 is substituted with an amino acid that cannot be phosphorylated by a kinase of the present invention, the polynucleotide coding thereof, the vector carrying the polynucleotide, or the virus or cell transformed with the vector can be used as a therapeutic agent for various cancers.