Identification of a retrovirus in human breast cancer J. F. Holland, Y. Wang, S. Mellana, J. Jiang, B. Pogo Abstract: Background: Breast cancer (BC) in mice is caused by mouse mammary tumor virus (MMTV). We have reported that 38% of BC in American women contain envelope gene sequences, 95% to 99% homologous to the env gene of MMTV implying the presence of a human mammary tumor virus (HMTV) (Cancer Res 55, 5173; 1995). Env positivity is high in regions with high incidence of BC (Western Europe, North Africa, the Americas, Australia) and low in low regions (Asia, Asia Minor) (Clin Cancer Res 10, 5647; 2004). Methods: Polymerase chain reaction (PCR), reverse transcriptase PCR (RT-PCR), and nucleotide sequencing were performed by standard. Methods: Env positive breast cancer cells were co-cultured for five days through a micropore barrier with normal breast or peripheral blood mononuclear cells (PBMC). Results: A complete 9.9 kb proviral structure has been identified, 95% homologous to MMTV. Unique differences from MMTV are systematically found in the long terminal repeat (LTR) gene of the HMTV. Normal tissues of the same patient do not contain sequences, thereby excluding endogenous sequences and genetic inheritance as mechanisms of transmission. In six of twelve experiments viral sequences were transferred to allogeneic breast cells and in four of six to allogeneic PBMC as detected by specific monoclonal antibody staining and by PCR. Conclusions: HMTV is an infectious agent, horizontally acquired, that can be transmitted from BC cells in vitro. These data establish that a substantial proportion of human BC is associated with a viral agent, HMTV, closely similar to MMTV, which is known to cause mammary tumors in mice. The correlation of HMTV with human BC incidence is consistent with considerations of causality. Abstract No: 548 Ann's NOTE: I spoke to Dr. James Holland who ran the breast service at Mt. Sinai Hospital in NYC about this. He has worked on this issue for MANY years. Everything takes many years in the cancer 'biz'. Remember we are NOT Doctors and have NO medical training. This site is like an Encylopedia - there are many pages, many links on many topics. Support our work with any size DONATION - see left side of any page - for how to donate. You can help raise awareness of CAM.