Figure 3. Temporarily blocking p53 during TBI suppresses aberrant expansion of premalignant thymocytes.

(a) PCR that assesses V–J recombination of the TCRβ locus of radiation-induced lymphomas that developed in either shp53 or control mice. The thymus from an unirradiated mouse was used as a control. (b) PCR assessing V–J recombination of the TCRβ locus of thymocytes from control and shp53 mice 150 days after 1.8 Gy × 4 TBI. Red asterisks indicate aberrant PCR bands. (c) Representative flow cytometry dot plots of thymocytes having normal (N) and aberrant (A) TCRβ rearrangement. Cells at different stages of thymocyte development were gated based on the expression of surface markers. CD4 single positive (CD4SP); CD8 single positive (CD8SP); DP: CD4⁺CD8⁺; DN3 : CD44⁻CD25⁺CD4⁻CD8⁻; DN2: CD44⁺CD25⁺CD4⁻CD8⁻; ETP: cKit^hiCD44⁺CD25⁻CD4⁻CD8⁻. (d–f) The percentage of cells at various stages of thymocyte development and the percentage of LSK cells in the bone marrow from control and shp53 mice 150 days after 1.8 Gy × 4 TBI. Black and red dots represent mice harbouring normal and aberrant TCRβ rearrangement, respectively. *P<0.05 by Students t-test. Data are presented as mean±s.e.m. (g) Expression of the ICN protein and (h) Hes1 mRNA in thymocytes having normal (N) and aberrant (A) TCRβ rearrangement.