2. Academic Validation
  3. Cyclin A/B RxL Macrocyclic Inhibitors to Treat Cancers with High E2F Activity

Cyclin A/B RxL Macrocyclic Inhibitors to Treat Cancers with High E2F Activity

  • bioRxiv. 2024 Aug 1:2024.08.01.605889. doi: 10.1101/2024.08.01.605889.
Shilpa Singh,  Catherine E Gleason,  Min Fang,  Yasmin N Laimon,  Vishal Khivansara,  Shanhai Xie,  Yavuz T Durmaz,  Aniruddha Sarkar,  Kenneth Ngo,  Varunika Savla,  Yixiang Li,  Muhannad Abu-Remaileh,  Xinyue Li,  Bishma Tuladhar,  Ranya Odeh,  Frances Hamkins-Indik,  Daphne He,  Miles W Membreno,  Meisam Nosrati,  Nathan N Gushwa,  Siegfried S F Leung,  Breena Fraga-Walton,  Luis Hernandez,  Miguel P Baldomero,  Bryan M Lent,  David Spellmeyer,  Joshua F Luna,  Dalena Hoang,  Yuliana Gritsenko,  Manesh Chand,  Megan K DeMart,  Sammy Metobo,  Chinmay Bhatt,  Justin A Shapiro,  Kai Yang,  Nathan J Dupper,  Andrew T Bockus,  John G Doench,  James B Aggen,  Li-Fen Liu,  Bernard Levin,  Evelyn W Wang,  Iolanda Vendrell,  Roman Fischer,  Benedikt Kessler,  Prafulla C Gokhale,  Sabina Signoretti,  Alexander Spektor,  Constantine Kreatsoulas,  Rajinder Singh,  David J Earp,  Pablo D Garcia,  Deepak Nijhawan,  Matthew G Oser
PMID: 39211113 DOI: 10.1101/2024.08.01.605889
Abstract

Cancer cell proliferation requires precise control of E2F1 activity; excess activity promotes Apoptosis. Here, we developed cell-permeable and bioavailable macrocycles that selectively kill small cell lung Cancer (SCLC) cells with inherent high E2F1 activity by blocking RxL-mediated interactions of cyclin A and cyclin B with select substrates. Genome-wide CRISPR/Cas9 knockout and random mutagenesis screens found that cyclin A/B RxL macrocyclic inhibitors (cyclin A/Bi) induced Apoptosis paradoxically by cyclin B- and Cdk2-dependent spindle assembly checkpoint activation (SAC). Mechanistically, cyclin A/Bi hyperactivate E2F1 and cyclin B by blocking their RxL-interactions with cyclin A and Myt1, respectively, ultimately leading to SAC activation and mitotic cell death. Base editor screens identified cyclin B variants that confer cyclin A/Bi resistance including several variants that disrupted cyclin B:Cdk interactions. Unexpectedly but consistent with our base editor and knockout screens, cyclin A/Bi induced the formation of neo-morphic Cdk2-cyclin B complexes that promote SAC activation and Apoptosis. Finally, orally-bioavailable cyclin A/Bi robustly inhibited tumor growth in chemotherapy-resistant patient-derived xenograft models of SCLC. This work uncovers gain-of-function mechanisms by which cyclin A/Bi induce Apoptosis in cancers with high E2F activity, and suggests cyclin A/Bi as a therapeutic strategy for SCLC and other cancers driven by high E2F activity.

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