Small molecular BCL6 inhibitor 79-6 is a cell-permeable oxindole compound that selectively inhibits the transcriptional repression activity of BCL6 but does not affect BCL6 protein levels. 79-6 binds an aromatic pocket situated in the BTB domain lateral groove, induces disruption of BCL6 transcriptional complexes, reactivation of BCL6 target genes and selective killing of BCL6-dependent DLBCL cells. BCL6 can also interact with MTA3 through its RD2 domain and represses the terminal differentiation. It recruits CtBP through its DBD domain and represses its own expression. 79-6 suppresses invasive ability and colony-forming ability in both of MCF-7 and MDA231 cells. The inhibition of BCL6 with 79-6 enhanced the mRNA expression of E-cadherin in both of MCF-7 and MDA231 cells. 79-6 reverses the functions of BCL6 in the positive regulation of EMT, invasion and transcriptional repression of E-cadherin in breast cancer cells.
