Effects of adenoviral wild-type p53 gene transfer in p53-mutated lymphoma cells

The present study assessed the ro Ie of adenoviral vector-mediated wild-typ e p53 gene transfer in B lymphoma cells. Deficiency of p53-mediated ce I I death is common inhuman cancer contributing to both tumorigenesis and chemo resistance. Lymphoma cells are being considered as suitable targets for gen e therapy protocols. Recently, we reported an adenoviral protocol leading t o highly efficient gene transfer to B lymphoma cells. All lymphoma cell lin es (n=5) tested here showed mutations in the p53 gene locus. The aim of thi s work was to transduce lymphoma cells with the wild-type p53 gene. Using t his protocol, 88% of Raj!, 75% of Daudi, and 45% of OCl-Ly8-LAM53 cells wer e transfected with the reporter gene green fluorescent protein at a multipl icity of infection of 200. The expression of green fluorescent protein in C A46 and BL41 cells was 27% and 42%, respectively. At this multiplicity of i nfection, growth characteristics of lymphoma cell lines were not changed si gnificantly. In contrast, cells transduced with wild-type p53 gene showed a n inhibition of proliferation as well as an increase in apoptosis. Cell los s by apoptosis after p53 gene transfer was up to 40% as compared to transdu ction with an irrelevant vector. In addition, we determined the effects of DNA damage produced by the DNA topoisomerase II inhibitor etoposide on wild -type p53 transfected lymphoma cells. In Ad-p53-transfected Raji cells, tre atment with the drug resulted in a marked increase of cell loss in comparis on to Ad-beta -Gal-transfected cells (45% vs. 77%). Interestingly, performi ng cytotoxicity studies, we could show an increased sensitivity of Raji and Daudi cells against immunological effector cells. In conclusion, transduct ion of wild-type p53 into lymphoma cells expressing mutated p53 was efficie nt and led to inhibition of proliferation and increase in apoptotic rate in some cell lines dependent on p53 mutation. This protocol should have an im pact on the use of lymphoma cells in cancer gene therapy protocols.