Adenoviral-mediated p53 transgene expression sensitizes both wild-type and null p53 prostate cancer cells in vitro to radiation

Int J Radiat Oncol Biol Phys. 2000 Dec 1;48(5):1507-12. doi: 10.1016/s0360-3016(00)01409-7.


Purpose/objective: The effect of adenoviral-mediated p53 transgene expression on the radiation response of two human prostate cancer cell lines, the p53(wild-type) LNCaP and p53(null) PC3 lines, was examined. The objective was to determine if this vector sensitizes cells to radiation independently of their p53 status.

Methods and materials: A recombinant adenovirus-5 vector (RPR/INGN 201, Introgen Therapeutics, Houston, TX) containing a CMV promoter and wild-type p53-cDNA (Ad5-p53) was used to facilitate p53 transgene expression. A multiplicity of infection (MOI) of 10-40 viral particles per cell was used, based on Ad5/CMV/lacz infection and staining for the beta-galactosidase reporter gene product. Clonogenic assays were performed to evaluate the degree of sensitization to radiation of viral-transduced cells compared with irradiated nontransduced controls. The relative efficacy of these treatments to induce apoptotic cell death was determined using the TUNEL assay.

Results: The delivery of Ad5-p53 (10 MOI) reduced control plating efficiency from 36.5% to 0.86% in the LNCaP cell line and from 75.1% to 4.1% in the PC3 cell line. After correcting for the effect of Ad5-p53 on plating efficiency, the surviving fraction after 2 Gy (SF2) of gamma-irradiation was reduced over 2.5-fold, from 0.187 to 0.072, with transgene p53 expression in the LNCaP cell line. Surviving fraction after 4 Gy (SF4) was reduced over 4.5-fold, from 0.014 to 0.003, after Ad5-p53 treatment. In the PC3 cell line, Ad5-p53 (40 MOI) reduced SF2 over 1.9-fold from 0.708 to 0.367, and SF4 over 6-fold from 0.335 to 0.056. In both the LNCaP and PC3 cell lines, the combination of Ad5-p53 plus radiation (2 Gy) resulted in supra-additive apoptosis (approximately 20% for LNCaP and approximately 15% for PC3 at 50 MOI), above that seen from the addition of the controls; control vector Ad5-pA plus RT (0.15% for LNCaP and 1.44% for PC3), Ad5-p53 alone (28.6% for LNCaP and 21.7% for PC3), RT alone (0% for LNCaP and 0.23% for PC3), or Ad5-pA alone (0.1% for LNCaP and 0.29% for PC3).

Conclusion: The clonogenic survival and apoptosis data demonstrate that p53 transgene expression sensitizes human prostate adenocarcinoma cells in vitro to irradiation. As this effect was observed in both the p53(wild-type) LNCaP and p53(null) PC3 lines, radiosensitization was independent of p53 status.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adenoviridae / genetics
  • Apoptosis / genetics*
  • Cell Survival / genetics
  • Gene Expression Regulation, Neoplastic / genetics*
  • Genes, Reporter
  • Genes, p53 / genetics*
  • Genetic Vectors / physiology
  • Humans
  • Male
  • Prostatic Neoplasms / genetics*
  • Prostatic Neoplasms / physiopathology
  • Prostatic Neoplasms / radiotherapy*
  • Radiation Tolerance / genetics*
  • Radiobiology
  • Transfection
  • Transgenes / genetics*
  • Tumor Cells, Cultured / radiation effects
  • beta-Galactosidase / genetics


  • beta-Galactosidase