OBJECTIVETo explore the role of protein kinase D3 (PKD3) in the regulation of matrix metalloproteinases 7 (MMP-7) expression in prostate cancer cells.

METHODSPC-3 cells were either stimulated with 100 nmol/L PMA to activate PKD3 kinase activity, or transiently transfected with PKD3 siRNA, and the relative expression level of MMP-7 mRNA were analyzed by real-time PCR using 2(-delta delta Ct) method. MMP-7 mRNA levels were also analyzed and quantified in HEK293 cells with over-expression of wild-type PKD3, PKD3 knockdown (using PKD3 siRNA), or over-expression of wild-type PKD3 followed by PKD3 knockdown.

RESULTSMMP-7 mRNA expression in PC3 cells was significantly decreased after PMA-induced PKD3 kinase activation. In contrast, PKD3 knockdown by siRNA transfection markedly increased MMP-7 mRNA level (P<0.01). MMP-7 mRNA level in HEK293 cells was significantly decreased by PKD3 over-expression, whereas obviously increased by PKD3 knockdown. Down-regulation of MMP-7 mRNA level in HEK293 induced by PKD3 over-expression was rescued by PKD3 knockdown.

CONCLUSIONPKD3 may contribute to the malignant progression of prostate cancer cells through negative regulation of MMP-7 expression.

Cell Line, Tumor ; Down-Regulation ; Gene Knockdown Techniques ; Humans ; Male ; Matrix Metalloproteinase 7 ; metabolism ; Prostatic Neoplasms ; enzymology ; metabolism ; Protein Kinase C ; metabolism ; Signal Transduction

OBJECTIVETo investigate the role of PKD3 in prostate-specific antigen (PSA) expression regulation in androgen-dependent prostate cancer cells and explore the mechanism.

METHODSLNCaP cells containing low level of PKD3 were transfected with pEGFP-C2 or pEGFP-PKD3 plasmid followed by dihydrotestosterone (DHT) treatment, and PSA mRNA level was analyzed by RT-QPCR using 2(-delta delta Ct) method. Wild-type or kinase-dead PKD3 plasmids, human androgen receptor plasmid pSVAR0, pMMTV-luc of AR luciferase reporter and renilla luciferase reporter pRL-SV40 were cotransfected into HEK293 cells, and after treatment with DHT for 24 h, the cells were harvested and AR transcriptional activity were determined by dual-luciferase reporter assay. The subcellular localization of endogenous PKD3 and AR and their colocalization induced by DHT were observed by confocal microscopy.

RESULTSPSA mRNA level triggered by DHT was significantly increased by overexpression of pEGFP-PKD3 in LNCaP cells compared with that in pEGFP-C2 control cells (P<0.001). AR transcription in response to DHT treatment was also significantly up-regulated by wild type PKD3 expression (P<0.001), but partially down-regulated by kinase-dead PKD3 mutant (P<0.01). Endogenous PKD3 and AR in LNCaP cells not only translocated from the cytoplasm to the nucleus, but also colocalized with each other after DHT stimulation.

CONCLUSIONElevated AR transcriptional activity and enhanced expression of PSA induced by PKD3 in response to DHT treatment suggest that PKD3 contributes to the proliferation and malignant growth of androgen-dependent prostate cancer cells.

Cell Line, Tumor ; Humans ; Male ; Neoplasms, Hormone-Dependent ; metabolism ; Prostate-Specific Antigen ; metabolism ; Prostatic Neoplasms ; metabolism ; Protein Kinase C ; metabolism ; Transcriptional Activation ; Up-Regulation