Activation of p53-dependent growth suppression in human cells by mutations in PTEN or PIK3CA

Jung Sik Kim, Carolyn Lee, Challice Bonifant, Habtom Ressom, Todd Waldman

Research output: Contribution to journalArticle

Abstract

In an effort to identify genes whose expression is regulated by activated phosphatidylinositol 3-kinase (PI3K) signaling, we performed microarray analysis and subsequent quantitative reverse transcription-PCR on an isogenic set of PTEN gene-targeted human cancer cells. Numerous p53 effectors were upregulated following PTEN deletion, including p21, GDF15, PIG3, NOXA, and PLK2. Stable depletion of p53 led to reversion of the gene expression program. Western blots revealed that p53 was stabilized in HCT116 PTEN-/- cells via an Akt1-dependent and p14ARF-independent mechanism. Stable depletion of PTEN in untransformed human fibroblasts and epithelial cells also led to upregulation of p53 and senescence-like growth arrest. Simultaneous depletion of p53 rescued this phenotype, enabling PTEN-depleted cells to continue proliferating. Next, we tested whether oncogenic PIK3CA, like inactivated PTEN, could activate p53. Retroviral expression of oncogenic human PIK3CA in MCF10A cells led to activation of p53 and upregulation of p53-regulated genes. Stable depletion of p53 reversed these PIK3CA-induced expression changes and synergized with oncogenic PIK3CA in inducing anchorage-independent growth. Finally, targeted deletion of an endogenous allele of oncogenic, but not wild-type, PIK3CA in a human cancer cell line led to a reduction in p53 levels and a decrease in the expression of p53-regulated genes. These studies demonstrate that activation of PI3K signaling by mutations in PTEN or PIIOCA can lead to activation of p53-mediated growth suppression in human cells, indicating that p53 can function as a brake on phosphatidylinositol (3,4,5)-triphosphate-induced mitogenesis during human cancer pathogenesis.

Original languageEnglish (US)
Pages (from-to)662-677
Number of pages16
JournalMolecular and cellular biology
Volume27
Issue number2
DOIs
StatePublished - Jan 1 2007
Externally publishedYes

Fingerprint

Mutation
Growth
Phosphatidylinositol 3-Kinase
p53 Genes
Up-Regulation
Tumor Suppressor Protein p14ARF
HCT116 Cells
Gene Expression
Neoplasms
Microarray Analysis
Reverse Transcription
Fibroblasts
Western Blotting
Epithelial Cells
Alleles
Phenotype
Cell Line
Polymerase Chain Reaction
Genes

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology

Cite this

Activation of p53-dependent growth suppression in human cells by mutations in PTEN or PIK3CA. / Kim, Jung Sik; Lee, Carolyn; Bonifant, Challice; Ressom, Habtom; Waldman, Todd.

In: Molecular and cellular biology, Vol. 27, No. 2, 01.01.2007, p. 662-677.

Research output: Contribution to journalArticle

Kim, Jung Sik ; Lee, Carolyn ; Bonifant, Challice ; Ressom, Habtom ; Waldman, Todd. / Activation of p53-dependent growth suppression in human cells by mutations in PTEN or PIK3CA. In: Molecular and cellular biology. 2007 ; Vol. 27, No. 2. pp. 662-677.
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