Protein Kinase D3 (PKD3) Contributes to Prostate Cancer Cell Growth and Survival Through a PKCε/PKD3 Pathway Downstream of Akt and ERK 1/2

Abstract

Protein kinase D (PKD) is a family of novel diacylglycerol/ phorbol ester targets that regulate many important cellular functions including cell growth and survival. We now provide experimental evidence to indicate that PKD3 contributes to prostate cancer cell growth and survival. Expression of PKD3 as well as PKD1 was significantly higher in human prostate tumors compared with normal tissues as revealed by immunohistochemistry. Moreover, PKD3 exhibited a marked increase in nuclear localization in tumor tissues, which correlated with tumor grade. Isoforms of PKD were differentially expressed and localized between normal and human prostate cancer cells. Increased protein expression and nuclear accumulation of PKD3 were observed in the more aggressive androgen-independent PC3 and DU145 cells compared with the less aggressive androgen-dependent LNCaP cells. Overexpression of wild-type PKD3 in LNCaP cells blocked phorbol 12-myristate 13-acetate (PMA)-induced apoptosis in association with inhibition of PMA-induced down-regulation of Akt activity, and prolonged extracellular signal-regulated kinase (ERK)1/2 activation. Overexpression of wild-type PKD3 also promoted S phase entry, whereas depletion of endogenous PKD3 resulted in G 0 -G 1 phase cell cycle arrest and inhibition of PC3 cell proliferation. In PC3 and DU145 cells, PKCE regulated PKD3 kinase activity and nuclear localization. Moreover, ectopical expression of PKD3 increased, whereas depletion of endogenous PKD3 reduced basal Akt and ERK1/2 activities. Further analysis showed that up-regulation of Akt activity induced by PKD3 required phosphatidylinositol-3-OH kinase and p38. In summary, our data indicate that PKD3 contributes to growth and survival of prostate cancer cells and may represent a novel therapeutic target for prostate cancer. [Cancer Res 2008;68(10):3844-53]

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

“…Overexpression of catalytically active PKD3 resulted in the hyperactivation of S6K1, whereas PKD3 knockdown reduced S6K1 phosphorylation. Interestingly, we did not observe any changes in the phosphorylation of Erk1/2 and Akt, kinases whose activation has previously been implicated in the context of PKD3-positive prostate cancer (10), indicating a selective effect of PKD3 on S6K1 in breast cancer cells. The two main S6K1 isoforms, p70 and p85, derive from the same gene and are produced by alternative translational initiation (16).…”

“…For example, PKD1/2-mediated phosphorylation of substrates such as slingshot homolog 1 and Ras and Rab interactor 1 leads to the inhibition of cell migration (6 -8), and reduced PKD1 expression levels were observed by immunohistological analyses of invasive breast cancer samples (9), suggesting that the loss of PKD1 may be associated with breast tumor progression. By contrast, Chen et al (10) showed that PKD3 is up-regulated in primary prostate cancers and prostate cancer cell lines and stimulates prosurvival pathways, indicating a positive correlation between PKD3 expression and tumorigenesis. This implies that PKD3 regulates a distinct set of substrates to fulfill such functions, which is in accordance with our recent findings that PKD3 selectively phosphorylates the multidomain protein GIT1 (G-protein coupled receptor kinase-interacting protein 1) to enhance cell spreading and motility (11).…”

“…The best characterized localization for the PKD isoforms is at the Golgi complex (1,4), and mTOR has also been described to localize to the Golgi membranes (22,23). However, PKD3 was also observed to localize to the nucleus in prostate cancer cells and VAMP2-positive vesicular structures in HEK 293 cells (10,24). Due to the lack of a commercially available antibody suited for the immunocytochemical detection of endogenous PKD3, we ectopically expressed GFP-tagged PKD3 in MDA-MB-231 cells where it localized mainly to the Golgi compartment, as revealed by costaining with the trans-Golgi marker p230, with smaller amounts found at the plasma membrane and in the cytosol (Fig.…”

Protein kinase D in vascular biology and angiogenesis

“…Prostate cancer cell lines exhibit increased levels of PKD3 and the degree of PKD3 nuclear localization has been positively correlated with tumor grade. PKD3 overexpression was also associated with increased growth and decreased apopotosis (48). These studies highlight the variable roles of the PKD isoforms in cancer biology and underline the importance of a more targeted and selective approach to anti-PKD therapeutics.…”

The downregulation of onzin expression by PKCɛ-ERK2 signaling and its potential role in AML cell differentiation

“…21,22 A series of evidence from the chemical inhibitions, RNA interferences, and transfections of dominant negative mutants and the constitutive activated forms of several representative PKCs strongly validated that PKCe is required for suppression of onzin expression by PMA. Furthermore, PKCs lead to the activation of the MAPK pathway by multiple signaling molecules such as protein kinase D, 23,24 which stimulates phosphorylation of transcription factors or inhibitors, for example AP-1, c-Jun, and Elk, finally regulating gene expression. For instance, PKCe inhibits human CYP11B2 gene expression through ERK1/2 signaling pathway and Jun B.…”