Abstract
Purpose: :
Pigment epithelium-derived factor (PEDF) exhibits indirect and direct anti-melanoma mechanisms of action. We have previously demonstrated that mouse PEDF gene transfection was able to decrease hepatic micrometastasis in a mouse ocular melanoma model. The purpose of this study is to explore the molecular mechanisms of the PEDF-mediated reduction of micrometastasis.
Methods: :
pLenti6.2/N-LumioTM/V5-DEST/mPEDF was transduced into the mouse melanoma B16LS9 cell line, and pLenti6.2/N-LumioTM/V5-DEST/LacZ was transduced a control. Transduced cell clones were selected by Blasticidin for 2 weeks and maintained in culture medium. The level of PEDF expression was detected by Western blot and SYBR green real-time PCR. Gene expression profiles of stably PEDF-overexpressing, vehicle control and wild-type B16LS9 cells were analyzed with Affymetrix GeneChip Mouse Genome 430 2.0 arrays representing approximately 34,000 transcripts.
Results: :
A total of 3212 transcripts exhibited at least 2-fold differences in their expression levels. PEDF gene and VEGF-A gene were up-regulated respectively 32.16-fold and 2.47-fold in the PEDF-transfected cells compared to the wild type cells, which means PEDF gene expressed 13.03-fold higher than VEGF gene in the PEDF-transfected cells. Contrarily, PEDF gene and VEGF-A gene were up-regulated respectively 1.05-fold and 4.4-fold in the LacZ-transfected cells compared to the wild type cells, and the ratio of PEDF to VEGF was 0.24. S100b, Junb and TRAF family member-associated Nf-kappa B activator (Tank) were down-regulated, and hypoxia-inducible factor 1, alpha subunit inhibitor (Hif1an), metastasis suppressor 1(Mtss1) and tissue inhibitor of metalloproteinase 2 (Timp2) were up-regulated in stable PEDF overexpressing B16LS9 cells.
Conclusions: :
PEDF gene overexpression results in an increase PEDF/VEGF ratio. The mechanism of inhibiting micrometastasis may be caused by the PEDF gene overexpression that inhibits NF-ΚB which leads to decreased melanoma cell proliferation with decreased JunB and HIF which regulate melanoma angiogenesis.
Keywords: gene/expression • gene microarray • melanoma