Polycomb complex protein BMI-1 is a polycomb ring finger oncogene that regulates the p16 and p19 cell cycle inhibitor genes. It is necessary for efficient self-renewing cell divisions of stem cells in several tissues and can be over-expressed in tumors. PTC-209 is a BMI-1 inhibitor (IC50 = ~ 0.5 μM) that irreversibly impairs colorectal cancer-initiating cell (CIC) growth. It reduces tumor growth in CIC xenograft assays and abrogates colorectal cancer cell self-renewal in vivo, reducing their tumorigenic potential.
