Molecular cloning and sequence analysis of the cDNAs derived from the myb transcripts show that ABPL-1 tumor produces a tripartate mRNA containing sequences derived from the viral gag and env genes fused to the myb coding region.
We previously reported a 660-bp mouse mammary tumor virus (MMTV)-like env gene sequence in approximately 38% of human breast cancer DNA, but not in normal breasts or other tumors.
Jaagsiekte sheep retrovirus (JSRV) and ovine nasal adenocarcinoma virus (ONAV) replicate in the airway and cause epithelial cell tumors through the activity of their envelope (Env) proteins.
These data indicate that 38-40% of human breast cancers contain gene sequences homologous to the MMTV env gene that are absent from other tumors and tissues.
Prompted by the observation of retroviral particle formation in teratocarcinoma cell lines and the consistent finding of antibodies against Gag and Env proteins encoded by human endogenous retrovirus (HERV)-K genomes in the sera of patients with classical seminoma, we studied ovarian and testicular germ cell tumours, their precursor lesions, dysgenetic gonads, and trophoblast lesions for expression of HERV-K sequences by in situ hybridization using radioactive and non-radioactive probes.
Elevated expression of the tumor suppressing protein p53 is associated with the presence of mouse mammary tumor-like env gene sequences (MMTV-like) in human breast cancer.
When the tumor reactivity of dominant clonotypic TCRs in each mouse was analyzed, 9 of 13 TCRs induced the secretion of IFNγ in response to, and showed killing of, B16F10 cells <i>in vitro</i>, and 2 of them showed strong antitumor activity <i>in vivo</i> Concerning their antigen specificity, 7 of them reacted to p15E peptide of endogenous murine leukemia virus-derived envelope glycoprotein 70, and the rest reacted to tumor-associated antigens expressed on EL4 lymphoma as well as B16 melanoma cells.