Abstract
Tumor antigen peptides on BALB/c leukemia RL♂1 that were recognized by cytotoxic T lymphocytes were shown to be derived from a normally unstranslated region of the akt proto-oncogene (Uenaka, A. et al., J. Exp. Med., 180: 1599, 1994). We show here that the murine leukemia virus (MuLV) long terminal repeat (LTR) was inserted directly into the exon of c-akt in RL♂1 leukemia and that transcription started from the cap site of the LTR. Translation appeared to start from the ATG codon created in the six nucleotides of unknown origin, which were inserted into the LTR/akt junction. The deduced molecular size is approximately Mr 59,000 due to the addition of 33 amino acid residues to the normally expressed c-AKT protein. Western blot analysis demonstrated the presence of Mr 59,000 molecules in an RL♂1 lysate, and their expression at about ten times the level of normal AKT molecules of Mr 56,000, which is consistent with the increased expression of akt mRNA demonstrated by Northern blot analysis. The findings show that the molecular alteration of AKT protein by insertion of MuLV LTR is the mechanism for creating rejection antigen peptides derived from the untranslated region of akt.
Footnotes
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↵1 This work was supported in part by a Grant-in-Aid for Cancer Research from the Japanese Ministry of Education, Science, and Culture.
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↵2 To whom requests for reprints should be addressed.
- Received August 15, 1995.
- Accepted September 21, 1995.
- ©1995 American Association for Cancer Research.