Phosphodiesterase Type 5 Inhibitors Synergize Vincristine in Killing Castration-Resistant Prostate Cancer Through Amplifying Mitotic Arrest Signaling
Journal
Frontiers in Oncology
Journal Volume
10
Pages
1274
Date Issued
2020
Author(s)
Abstract
Combination therapies that display cancer-killing activities through either coexistent targeting of several cellular factors or more efficient suppression of a specific pathway are generally used in cancer treatment. Sildenafil, a specific phosphodiesterase type 5 (PDE5) inhibitor, has been suggested to display both cardioprotective and neuroprotective activities that provide a rationale for the combination with vincristine on the treatment against castration-resistant prostate cancer (CRPC). In the present work, vincristine arrested cells in the metaphase stage of mitosis. Vincristine-induced mitotic arrest was identified by Cdk1 activation (i.e., increased Cdk1Thr161 phosphorylation and decreased Cdk1Tyr15 phosphorylation), cyclin B1 upregulation, and increased phosphorylation of multiple mitotic proteins and stathmin. Sildenafil synergistically potentiated vincristine-induced mitotic arrest and a dramatic increase of mitotic index. Furthermore, sildenafil potentiated vincristine-induced mitochondrial damage, including Mcl-1 downregulation, Bcl-2 phosphorylation and downregulation, Bak upregulation and loss of mitochondrial membrane potential, and sensitized caspase-dependent apoptotic cell death. Sildenafil-mediated synergistic effects were mimicked by other PDE5 inhibitors including vardenafil and tadalafil, and also by PDE5A knockdown in cells, suggesting PDE5-involved mechanism. Notably, sildenafil amplified vincristine-induced phosphorylation and cleavage of BUBR1, a protein kinase in spindle assembly checkpoint (SAC) function and chromosome segregation. Sildenafil also significantly decreased kinetochore tension during SAC activation. Moreover, sildenafil synergized with vincristine on suppressing tumor growth in an in vivo model. In conclusion, the data suggest that sildenafil, in a PDE5-dependent manner, potentiates vincristine-induced mitotic arrest signaling, and sensitizes mitochondria damage–involved apoptosis in CRPC. Both in vitro and in vivo data suggest the combination potential of PDE5 inhibitors and vincristine on CRPC treatment. ? Copyright ? 2020 Hsu, Leu, Hsu, Ho, Liu and Guh.
SDGs
Other Subjects
Bub1 related protein; cyclin B1; cyclin dependent kinase 1; nicotinamide adenine dinucleotide adenosine diphosphate ribosyltransferase 1; phosphodiesterase V inhibitor; protein Bak; protein bcl 2; protein bcl xl; protein mcl 1; sildenafil; stathmin; tadalafil; vardenafil; vincristine; animal experiment; animal model; animal tissue; apoptosis; Article; castration resistant prostate cancer; cell proliferation; cell synchronization; controlled study; DNA fragmentation assay; DU145 cell line; flow cytometry; gene knockdown; genetic transfection; human; human cell; immunofluorescence; mitochondrial membrane potential; mitosis index; mitosis inhibition; mouse; MTT assay; neurite outgrowth; nonhuman; PC-3 [Human prostate carcinoma] cell line; protein expression; protein phosphorylation; tumor growth; tumor volume; upregulation; Western blotting
Publisher
Frontiers Media S.A.
Type
journal article