Inhibition or degradation of anti-apoptotic protein BCL-XL is a viable strategy for cancer treatment. Despite the recent development of PROTACs for degradation of BCL-XL, the E3 ligases are confined to the commonly used VHL and CRBN. Herein we report the development of MDM2-BCL-XL PROTACs using MDM2 as E3 ligase for degradation of BCL-XL. Three MDM2-BCL-XL PROTACs derived from MDM2 inhibitor Nutlin-3, which can also upregulate p53, and BCL-2/BCL-XL inhibitor ABT-263 with different linker length were designed, synthesized, and evaluated in vitro. We found BMM4 exhibited potent, selective degradation activity against BCL-XL and stabilized tumor suppressor p53 in U87, A549 and MV-4-11 cancer cell lines. Moreover, combination of BMM4 and BCL-2 inhibitor ABT-199 showed synergistic antiproliferative activity. The unique dual-functional PROTACs offers an alternative strategy for targeted protein degradation.
Keywords: BCL-XL; MDM2 E3 ligase; PROTAC; targeted protein degradation.