Novel anti-metastatic action of cidofovir mediated by inhibition of E6/E7, CXCR4 and Rho/ROCK signaling in HPV tumor cells

PLoS One. 2009;4(3):e5018. doi: 10.1371/journal.pone.0005018. Epub 2009 Mar 26.

Abstract

Cervical cancer is frequently associated with HPV infection. The expression of E6 and E7 HPV oncoproteins is a key factor in its carcinogenicity and might also influence its virulence, including metastatic conversion. The cellular mechanisms involved in metastatic spread remain elusive, but pro-adhesive receptors and their ligands, such as SDF-1alpha and CXCR4 are implicated. In the present study, we assessed the possible relationship between SDF-1alpha/CXCR4 signaling, E6/E7 status and the metastatic process. We found that SDF-1alpha stimulated the invasion of E6/E7-positive cancer cell lines (HeLa and TC-1) in Matrigel though CXCR4 and subsequent Rho/ROCK activation. In pulmonary metastatic foci generated by TC-1 cells IV injection a high proportion of cells expressed membrane-associated CXCR4. In both cases models (in vitro and in vivo) cell adhesion and invasion was abrogated by CXCR4 immunological blockade supporting a contribution of SDF-1alpha/CXCR4 to the metastatic process. E6 and E7 silencing using stable knock-down and the approved anti-viral agent, Cidofovir decreased CXCR4 gene expression as well as both, constitutive and SDF-1alpha-induced cell invasion. In addition, Cidofovir inhibited lung metastasis (both adhesion and invasion) supporting contribution of E6 and E7 oncoproteins to the metastatic process. Finally, potential signals activated downstream SDF-1alpha/CXCR4 and involved in lung homing of E6/E7-expressing tumor cells were investigated. The contribution of the Rho/ROCK pathway was suggested by the inhibitory effect triggered by Cidofovir and further confirmed using Y-27632 (a small molecule ROCK inhibitor). These data suggest a novel and highly translatable therapeutic approach to cervix cancer, by inhibition of adhesion and invasion of circulating HPV-positive tumor cells, using Cidofovir and/or ROCK inhibition.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alphapapillomavirus
  • Cell Line, Tumor
  • Chemokine CXCL12 / metabolism
  • Cidofovir
  • Cytosine / analogs & derivatives*
  • Cytosine / pharmacology
  • Humans
  • Neoplasm Metastasis / drug therapy*
  • Oncogene Proteins, Viral / antagonists & inhibitors*
  • Organophosphonates / pharmacology*
  • Papillomavirus E7 Proteins / antagonists & inhibitors
  • Receptors, CXCR4 / antagonists & inhibitors*
  • Signal Transduction / drug effects
  • rho GTP-Binding Proteins / metabolism*
  • rho-Associated Kinases / metabolism*

Substances

  • CXCR4 protein, human
  • Chemokine CXCL12
  • E6 protein, human papillomavirus type 1
  • Oncogene Proteins, Viral
  • Organophosphonates
  • Papillomavirus E7 Proteins
  • Receptors, CXCR4
  • Cytosine
  • rho-Associated Kinases
  • rho GTP-Binding Proteins
  • Cidofovir