Effects of p21cip1/waf1 overexpression on growth, apoptosis and differentiation in human colon carcinoma cells

Int J Oncol. 2005 Jul;27(1):69-76.


The cyclin-dependent kinase inhibitor p21cip1/waf1 negatively regulates the progression of cell cycle and the potential usefulness of p21cip1/waf1 gene is proposed in gene therapy. However, studies have demonstrated a protective role of p21cip1/waf1 against apoptosis and little is known about effects of ectopic expression of p21cip1/waf1 on differentiation of colon cancer cells. In the present study, we found diffuse p21cip1/waf1 expression in only a few clinical samples of colorectal cancer with wild-type p53 gene. To explore the role of p21cip1/waf1 in cell growth, apoptosis and differentiation, we constitutively overexpressed p21cip1/waf1 in HT29 colon carcinoma cells. Ectopic overexpression of p21cip1/waf1 was associated with inhibition of CDK2-associated kinase activity, indicating the functionality of the introduced p21cip1/waf1 gene. Overexpression of p21cip1/waf1 caused an appreciable growth inhibition in monolayer and soft agar cultures and it significantly reduced sodium butyrate- but not 5-fluorouracil-induced apoptosis. p21cip1/waf1 overexpressing cells exhibited marked decrease of intestinal differentiation when assayed with intestinal alkaline phosphatase. Our findings suggest that introduction of p21cip1/waf1 gene into colon cancer cells may be useful for inhibiting cell growth but caution should be taken regarding the increased resistance to certain apoptosis-inducing agents and dysregulation of endogenous p21cip1/waf1-mediated differentiation process.

MeSH terms

  • Agar / chemistry
  • Alkaline Phosphatase / metabolism
  • Apoptosis*
  • Blotting, Western
  • Butyrates / pharmacology
  • Carcinoma / metabolism
  • Carcinoma / pathology*
  • Cell Cycle Proteins / metabolism*
  • Cell Differentiation
  • Cell Line, Tumor
  • Cell Proliferation
  • Colonic Neoplasms / metabolism
  • Colonic Neoplasms / pathology*
  • Cyclin-Dependent Kinase Inhibitor p21
  • DNA Mutational Analysis
  • Flow Cytometry
  • Fluorouracil / pharmacology
  • Gene Expression Regulation, Neoplastic*
  • Humans
  • Inhibitory Concentration 50
  • Isobutyrates
  • Mutation
  • Polymerase Chain Reaction
  • Polymorphism, Single-Stranded Conformational
  • Time Factors
  • Tumor Suppressor Protein p53 / metabolism


  • Butyrates
  • CDKN1A protein, human
  • Cell Cycle Proteins
  • Cyclin-Dependent Kinase Inhibitor p21
  • Isobutyrates
  • Tumor Suppressor Protein p53
  • isobutyric acid
  • Agar
  • Alkaline Phosphatase
  • Fluorouracil