PKD2 and PKD3 Promote Prostate Cancer Cell Invasion via uPA by Shifting Balance Between NF-κB and HDAC1

Abstract

SummaryAlthough protein kinase D3 (PKD3) has been shown to contribute to prostate cancer cell growth and survival, the role of PKD in prostate cancer cell motility remains unclear. Here, we show that PKD2 and PKD3 promote nuclear factor kappa B (NF-kB) signaling and urokinase-type plasminogen activator (uPA) expression/activation, which are crucial for prostate cancer cell invasion. Silencing of endogenous PKD2 and/or PKD3 markedly decreased prostate cancer cell migration and invasion, reduced uPA and uPA receptor (uPAR) expression and increased plasminogen activator inhibitor-2 (PAI-2) expression. These results were further substantiated by the finding that PKD2 and PKD3 promoted the activity of uPA and matrix metalloproteinase 9 (MMP9). Furthermore, depletion of PKD2 and/or PKD3 decreased the level of binding of the p65 subunit of NF-kB to the promoter of the gene encoding uPA (PLAU), suppressing transcriptional activation of uPA. Endogenous PKD2 and PKD3 interacted with inhibitor of NF-kB (IkB) kinase b (IKKb); PKD2 mainly regulated the phosphorylated IKK (pIKK)-phosphorylated IkB (pIkB)-IkB degradation cascade, p65 nuclear translocation, and phosphorylation of Ser276 on p65, whereas PKD3 was responsible for the phosphorylation of Ser536 on p65. Conversely, inhibition of uPA transactivation by PKD3 silencing was rescued by constitutive Ser536 p65 phosphorylation, and reduced tumor cell invasion resulting from PKD2 or PKD3 silencing was rescued by ectopic expression of p65. Interestingly, PKD3 interacted with histone deacetylase 1 (HDAC1), suppressing HDAC1 expression and decreasing its binding to the uPA promoter. Moreover, depletion of HDAC1 resulted in recovery of uPA transactivation in PKD3-knockdown cells. Taken together, these data suggest that PKD2 and PKD3 coordinate to promote prostate cancer cell invasion through p65 NF-kB-and HDAC1-mediated expression and activation of uPA.

Opposing Growth Regulatory Roles of Protein Kinase D Isoforms in Human Keratinocytes

“…PKD1 and PKD2 share higher homology in their structure than with PKD3, which lacks some regulatory elements including the N terminus hydrophobic domain or the C terminus PDZ binding motif (41) and contains divergent pleckstrin homology and C1 domain (42,43). Contrary to our findings in normal cells, recent studies in cancer cell lines have suggested coordinated functions of PKD2 and PKD3 in promoting cancer cell growth and invasion (33,44). This apparent contradiction in PKD2 signaling in normal and cancer cells could be explained by the fact that cancer cells resist inhibitory signals that might otherwise stop their growth (45).…”

Elevated Protein Kinase D3 (PKD3) Expression Supports Proliferation of Triple-negative Breast Cancer Cells and Contributes to mTORC1-S6K1 Pathway Activation

“…By contrast, in lung cancer cells, PKD3 was identified as part of a bone metastatic signature (42), and silencing of PKD3 in prostate cancer cells was shown to reduce in vitro proliferation, migration, invasion, and xenograft growth in nude mice (43). Mechanistically, PKD3 promoted the expression and secretion of cytokines and extracellular proteases such as matrix metalloproteinase 9 and urokinase-type plasminogen activator via activation of NFB and histone deacetylase signaling pathways, thereby positively contributing to cell migration and invasion (43,44). Furthermore, silencing of PKD2 in MCF7 cells promoted cell spreading (7), whereas PKD3 knockdown in the same cell line (data not shown) and in MDA-MB-231 cells as shown in this study impaired cell spreading.…”

A Novel Conserved Domain Mediates Dimerization of Protein Kinase D (PKD) Isoforms

“…For instance, PKDs mediate pro-survival signaling induced by oxidative stress (8); control fission of secretory vesicles from the transGolgi network (TGN) (9 -13); regulate cofilin-mediated F-actin dynamics underlying cell motility (14, 15); modulate proliferation and intensity of signal transduction in T cells (6,16,17); de-repress gene transcription in heart, skeletal muscle, and immune cells by phosphorylating type IIa histone deacetylases (HDACs) (18 -22); elicit expression of ϳ85 genes in Caenorhabditis elegans intestine that coordinately defend animals against bacterial pathogens (23); and enable associative learning in C. elegans by simultaneously transmitting environmental signals to a neuronal circuit and the intestine (24). Dysregulation of PKDs contributes to cancer phenotypes, cardiac hypertrophy, and heart failure (18,19,(25)(26)(27).Three genes encode mammalian PKD1, PKD2, and PKD3, which contain conserved regulatory and catalytic domains (3, 4). PKDs are broadly expressed, but levels of individual isoforms vary with cell type.…”