Specific Irreversible Cell-Cycle Arrest and Depletion of Cancer Cells Obtained by Combining Curcumin and the Flavonoids Quercetin and Fisetin.

Background: Induced senescence could be exploited to selectively counteract the proliferation of cancer cells and target them for senolysis. We examined the cellular senescence induced by curcumin and whether it could be targeted by fisetin and quercetin, flavonoids with senolytic activity. Methods: Cell-cycle profiles, chromosome number and structure, and heterochromatin markers were evaluated via flow cytometry, metaphase spreads, and immunofluorescence, respectively. The activation of p21waf1/cip1 was assessed via RT-qPCR and immunoblotting. Senescent cells were detected via SA-ß-Galactosidase staining. Results: We report that curcumin treatment specifically triggers senescence in cancer cells by inducing mitotic slippage and DNA damage. We show that curcumin-induced senescence is p21waf1/cip1-dependent and characterized by heterochromatin loss. Finally, we found that flavonoids clear curcumin-induced senescent cancer cells. Conclusions: Our findings expand the characterization of curcumin-induced cellular senescence in cancer cells and lay the foundation for the combination of curcumin and flavonoids as a possible anti-cancer therapy.

Transcriptomic Changes Following Partial Depletion of CENP-E in Normal Human Fibroblasts.

The centromere is a fundamental chromosome structure in which the macro-molecular kinetochore assembles and is bound by spindle microtubules, allowing the segregation of sister chromatids during mitosis. Any alterations in kinetochore assembly or functioning or kinetochore-microtubule attachments jeopardize chromosome stability, leading to aneuploidy, a common feature of cancer cells. The spindle assembly checkpoint (SAC) supervises this process, ensuring a faithful segregation of chromosomes. CENP-E is both a protein of the kinetochore and a crucial component of the SAC required for kinetochore-microtubule capture and stable attachment, as well as congression of chromosomes to the metaphase plate. As the function of CENP-E is restricted to mitosis, its haploinsufficiency has been used to study the induced cell aneuploidy; however, the gene expression profile triggered by CENP-E reduction in normal cells has never been explored. To fill this gap, here we investigated whether a gene network exists that is associated with an siRNA-induced 50% reduction in CENP-E and consequent aneuploidy. Gene expression microarray analyses were performed at early and late timepoints after transfection. Initially, cell cycle regulation and stress response pathways were downregulated, while afterwards pathways involved in epithelial-mesenchymal transition, hypoxia and xenobiotic metabolism were altered. Collectively, our results suggest that CENP-E reduction triggers a gene expression program that recapitulates some features of tumor cells.