Loss of p53 protein during radiation transformation of primary human mammary epithelial cells

David E. Wazer, Qiuming Chu, Xiao Long Liu, Qingshen Gao, Homa Safaii, Vimla Band

Research output: Contribution to journalArticle

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Abstract

The causative factors leading to breast cancer are largely unknown. Increased incidence of breast cancer following diagnostic or therapeutic radiation suggests that radiation may contribute to mammary oncogenesis. This report describes the in vitro neoplastic transformation of a normal human mammary epithelial cell strain, 76N, by fractionated γ-irradiation at a clinically used dose (30 Gy). The transformed cells (76R-30) were immortal, had reduced growth factor requirements, and produced tumors in nude mice. Remarkably, the 76R-30 cells completely lacked the p53 tumor suppressor protein. Loss of p53 was due to deletion of the gene on one allele and a 26- bp deletion within the third intron on the second allele which resulted in abnormal splicing out of either the third or fourth exon from the mRNA. PCR with a mutation-specific primer showed that intron 3 mutation was present in irradiated cells before selection for immortal phenotype. 76R-30 cells did not exhibit G1 arrest in response to radiation, indicating a loss of p53- mediated function. Expression of the wild-type p53 gene in 76R-30 cells led to their growth inhibition. Thus, loss of p53 protein appears to have contributed to neoplastic transformation of these cells. This unique model should facilitate analyses of molecular mechanisms of radiation-induced breast cancer and allow identification of p53-regulated cellular genes in breast cells.

Original languageEnglish (US)
Pages (from-to)2468-2478
Number of pages11
JournalMolecular and cellular biology
Volume14
Issue number4
DOIs
Publication statusPublished - Apr 1994

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ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology

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