¹Department of Biological Sciences, Hunter College of the City University of New York, New York, NY, USA

Correspondence: Dr DA Foster, Department of Biological Sciences, Hunter College of the City University of New York, 695 Park Avenue, New York, NY 10021, USA. E-mail: foster@genectr.hunter.cuny.edu

²Current address: Novartis Institute, Cambridge, MA 02139, USA.

Received 13 January 2006; Revised 19 April 2006; Accepted 4 May 2006; Published online 19 June 2006.

Abstract

p53 is the most commonly mutated gene in human cancer. Although the loss of tumor suppressor functions for p53 in tumorigenesis is well characterized, gain-of-function p53 mutations observed in most cancers are not as widely appreciated. The human breast cancer cell line MDA-MB-231, which has high levels of a mutant p53, has high levels of phospholipase D (PLD) activity, which provides a survival signal in these cells when deprived of serum growth factors. We report here that the mutant p53 in MDA-MB-231 cells is stabilized by the elevated PLD activity in these cells. Surprisingly, the survival of MDA-MB-231 cells deprived of serum was dependent on the mutant p53. These data indicate that a mutant p53, stabilized by elevated PLD activity, can contribute to the suppression of apoptosis in a human breast cancer cell line and suggest a rationale for the selection of p53 mutations early in tumorigenesis to suppress apoptosis in an emerging tumor.