Dexamethasone inhibits the phosphorylation of retinoblastoma protein in the suppression of human vascular smooth muscle cell proliferation

Todd D. Reil, Vikram S. Kashyap, Rajabrata Sarkar, Julie Freishlag, Hugh A. Gelabert

Research output: Contribution to journalArticle

15 Scopus citations

Abstract

We have previously demonstrated that dexamethasone (DEX) suppresses neointimal hyperplasia and proliferation of rat aortic smooth muscle cells (SMC) by inducing a late G1 phase cell cycle arrest. Phosphorylation of retinoblastoma protein (Rb) regulates cell proliferation by controlling progression from G1 to S phase of the cell cycle. We hypothesized that DEX inhibits human vascular SMC proliferation and causes cell cycle arrest through inhibition of Rb phosphorylation. Human aortic SMC were cultured and treated with incremental doses of DEX. Cell counts and [3H]thymidine uptake were determined after 72 h. To examine the effects of DEX on the cell cycle, cells were synchronized by serum deprivation, restimulated to enter G1 phase, and treated with 10-5) M DEX, and protein was extracted at sequential time points. Flow cytometry was performed to track cell cycle progression. Western blots were performed to examine Rb phosphorylation. DEX inhibited smooth muscle cell proliferation and DNA synthesis in a concentration-dependent fashion. Flow cytometry indicated that DEX induces a G1 phase cell cycle arrest. DEX inhibited the phosphorylation of Rb protein compared to control. DEX inhibits the proliferation of human vascular SMC by inducing G1 phase cell cycle arrest. DEX inhibited the phosphorylation of Rb, a key step in the progression of the cell from G1 to S phase. Elucidation of the mechanism of DEX may be helpful in treatment strategies for preventing neointimal hyperplasia as well as other disorders of cell proliferation. (C) 2000 Academic Press.

Original languageEnglish (US)
Pages (from-to)108-113
Number of pages6
JournalJournal of Surgical Research
Volume92
Issue number1
DOIs
StatePublished - Jul 2000

Keywords

  • Cell cycle
  • Cell proliferation
  • Dexamethasone
  • Human vascular smooth muscle cells
  • Neointimal hyperplasia
  • Retinoblastoma protein

ASJC Scopus subject areas

  • Surgery

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