Protein kinase D3 is involved in negative regulation of MMP-7 in prostate cancer cells / 南方医科大学学报

<p><b>OBJECTIVE</b>To explore the role of protein kinase D3 (PKD3) in the regulation of matrix metalloproteinases 7 (MMP-7) expression in prostate cancer cells.</p><p><b>METHODS</b>PC-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.</p><p><b>RESULTS</b>MMP-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.</p><p><b>CONCLUSION</b>PKD3 may contribute to the malignant progression of prostate cancer cells through negative regulation of MMP-7 expression.</p>

PKD3 contributes to up-regulation of prostate-specific antigen in prostate cancer cells / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the role of PKD3 in prostate-specific antigen (PSA) expression regulation in androgen-dependent prostate cancer cells and explore the mechanism.</p><p><b>METHODS</b>LNCaP 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.</p><p><b>RESULTS</b>PSA 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.</p><p><b>CONCLUSION</b>Elevated 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.</p>