Characterization of viral particles isolated from primary cultures of human breast cancer cells.
The association of human breast cancer with sequences similar to the mouse mammary tumor virus (MMTV) has been shown, but convincing evidence for the presence of viral particles in breast tumors has been lacking. We have described the complete proviral structure of a retrovirus in human breast cancer. This provirus, designated as human mammary tumor virus (HMTV), was 95% homologous to MMTV and revealed features of a replication-competent virus. We have therefore investigated the production of viral particles in primary cultures of human breast cancer (MSSM). Cells isolated from ascites or pleural effusions of patients with metastatic breast cancer contained viral sequences in their DNA, expressed Env protein, and showed retroviral particles by electron microscopy. Viral particles from culture media exhibited morphologic features of beta-retroviruses sedimenting at buoyant densities of 1.12 to 1.18 g/mL in sucrose gradients and showed reverse transcriptase activity. cDNA sequences from virion RNA were synthesized, amplified, and sequenced and all the virion genes were detected and 70% of the virion RNA was sequenced. The sequence homologies were, respectively, 85% to 95% compared with the MMTV and HMTV proviruses we have previously described. These results clearly show that breast cancer cells in primary cultures produced HMTV viral particles that are similar to the mouse virus and which may play a role in human breast cancer pathogenesis.
Melana
Stella M
SM
Department of Medicine, Mount Sinai School of Medicine, New York, New York 10029, USA.
Nepomnaschy
Irene
I
Sakalian
Michael
M
Abbott
Andrea
A
Hasa
Jennifer
J
Holland
James F
JF
Pogo
Beatriz G T
BG
D000595:Amino Acid Sequence; D001943:Breast Neoplasms / Q000821:virology*; D006801:Humans; D008969:Molecular Sequence Data; D012367:RNA, Viral / Q000032:analysis / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014407:Tumor Cells, Cultured; D014771:Virion / Q000235:genetics* / Q000302:isolation & purification
D012367:RNA, Viral