Dentin sialophosphoprotein (DSPP) gene-silencing inhibits key tumorigenic activities in human oral cancer cell line, OSC2

Rajeshree Joshi, Amany Tawfik, Nneka Edeh, Veronica Mccloud, Stephen Looney, Jill Lewis, Stephen Hsu, Kalu U.E. Ogbureke

Research output: Contribution to journalArticle

18 Scopus citations

Abstract

Background: We determined recently that dentin sialophosphoprotein (DSPP), a member of the SIBLING (Small integrin-binding ligand N-linked glycoproteins) family of phosphoglycoproteins, is highly upregulated in human oral squamous cell carcinomas (OSCCs) where upregulation is associated with tumor aggressiveness. To investigate the effects of DSPP-silencing on the tumorigenic profiles of the oral cancer cell line, OSC2, short-hairpin RNA (shRNA) interference was employed to silence DSPP in OSC2 cells. Methodology/Principal Findings: Multiple regions of DSPP transcript were targeted for shRNA interference using hDSP-shRNA lentiviral particles designed to silence DSPP gene expression. Control shRNA plasmid encoding a scrambled sequence incapable of degrading any known cellular mRNA was used for negative control. Following puromycin selection of stable lines of DSSP-silenced OSC2 cells, phenotypic hallmarks of oral carcinogenesis were assayed by western blot and RT-PCR analyses, MTT (cell-viability), colony-formation, modified Boyden-Chamber (migration and invasion), and flow cytometry (cell-cycle and apoptosis) analyses. DSPP-silenced OSC2 cells showed altered cell morphology, reduced viability, decreased colony-formation ability, decreased migration and invasion, G0/G1 cell-cycle arrest, and increased tumor cell sensitivity to cisplatin-induced apoptosis. Furthermore, MMP-2, MMP-3, MMP-9, VEGF, Ki-67, p53, and EGFR were down-regulated. There was a direct correlation between the degree of DSPP-silencing and MMP suppression, as indicated by least squares regression: MMP-2 {(y=0.850x, p<0.001) (y =1.156x, p<0.001)}, MMP-3 {(y= 0.994x, p<0.001) (y=1.324x, p= 0.004)}, and MMP-9 {(y= 1.248x, p =0.005, y=0.809, p= 0.013)}. Conclusions/Significance: DSPP-silencing in OSC2 cell decreased salient hallmarks of oral tumorigenesis and provides the first functional evidence of a potential key role for DSPP in oral cancer biology. The down-regulation of MMP-2, MMP-3, MMP-9, p53 and VEGF in DSPP-silenced OSC2 cells provides a significant functional/molecular framework for deciphering the mechanisms of DSPP activities in oral cancer biology.

Original languageEnglish (US)
Article numbere13974
JournalPloS one
Volume5
Issue number11
DOIs
StatePublished - 2010

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)
  • Agricultural and Biological Sciences(all)
  • General

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