ABSTRACT
Proper cell division relies on the coordinated regulation between a structural component, the mitotic spindle, and a regulatory component, anaphase-promoting complex/cyclosome (APC/C). Hematopoietic PBX-interacting protein (HPIP) is a microtubule-associated protein that plays a pivotal role in cell proliferation, cell migration, and tumor metastasis. Here, using HEK293T and HeLa cells, along with immunoprecipitation and immunoblotting, live-cell imaging, and protein-stability assays, we report that HPIP expression oscillates throughout the cell cycle and that its depletion delays cell division. We noted that by utilizing its D box and IR domain, HPIP plays a dual role both as a substrate and inhibitor, respectively, of the APC/C complex. We observed that HPIP enhances the G2/M transition of the cell cycle by transiently stabilizing cyclin B1 by preventing APC/C-Cdc20-mediated degradation, thereby ensuring timely mitotic entry. We also uncovered that HPIP associates with the mitotic spindle and that its depletion leads to the formation of multiple mitotic spindles and chromosomal abnormalities, results in defects in cytokinesis, and delays mitotic exit. Our findings uncover HPIP as both a substrate and an inhibitor of APC/C-Cdc20 that maintains the temporal stability of cyclin B1 during the G2/M transition and thereby controls mitosis and cell division.
Subject(s)
Anaphase-Promoting Complex-Cyclosome/metabolism , Cdc20 Proteins/metabolism , Cell Cycle , Cyclin B1/chemistry , Gene Expression Regulation/drug effects , Intracellular Signaling Peptides and Proteins/pharmacology , Mitosis , Anaphase-Promoting Complex-Cyclosome/antagonists & inhibitors , Anaphase-Promoting Complex-Cyclosome/genetics , Cdc20 Proteins/antagonists & inhibitors , Cdc20 Proteins/genetics , HEK293 Cells , HeLa Cells , Humans , Spindle Apparatus , Substrate SpecificityABSTRACT
Two series of diaziridinyl quinone isoxazole derivatives were prepared and evaluated for their cytotoxic activity against MCF7, HeLa, BT549, A549 and HEK293 cell lines and interaction with tubulin. Compounds (6A-M: ) showed promising activity against all the 5 human cancer cell lines. Compounds 6A: , 6E: and 6 M: were potent [IC50 ranging between 2.21 µg to 2.87 µg] on ER-positive MCF7 cell line similar to the commercially available drug molecule Doxorubicin. The results from docking models are in consistent with the experimental values which demonstrated the favourable binding modes of compounds 6A-M: to the interface of α- and ß-tubulin dimer.
