title: Effect of p16 on glucocorticoid response in a B-cell lymphoblast cell line.
abstract: OBJECTIVE
  It has been suggested that p16 has a role in glucocorticoid (GC)-related apoptosis in leukemic cells, but the exact mechanisms have yet to be clarified. We evaluated the relationship between the GC response and p16 expression in a lymphoma cell line.
  
  
  METHODS
  We used p16 siRNA transfection to construct p16-inactivated cells by using the B-cell lymphoblast cell line NC-37. We compared glucocorticoid receptor (GR) expression, apoptosis, and cell viability between control (p16+ NC-37) and p16 siRNA-transfected (p16- NC-37) cells after a single dose of dexamethasone (DX).
  
  
  RESULTS
  In both groups, there was a significant increase in cytoplasmic GR expression, which tended to be higher for p16+ NC-37 cells than for p16- NC37 cells at all times, and the difference at 18 h was significant (P<0.05). Similar patterns of early apoptosis were observed in both groups, and late apoptosis occurred at higher levels at 18 h when the GR had already been downregulated (P<0.05). Cell viability decreased in both groups but the degree of reduction was more severe in p16+ NC-37 cells after 18 h (P<0.05).
  
  
  CONCLUSIONS
  These results suggest a relationship between GR expression and cell cycle inhibition, in which the absence of p16 leads to reduced cell sensitivity to DX.
authors.affiliation: Department of Pediatrics, College of Medicine, Hanyang University, Seoul, Korea.
authors.forename: Sun-Young
authors.initials: SY
authors.lastname: Kim
authors.forename: Kyung-Yil
authors.initials: KY
authors.lastname: Lee
authors.forename: Dae-Chul
authors.initials: DC
authors.lastname: Jeong
authors.forename: Hak-Ki
authors.initials: HK
authors.lastname: Kim