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 β-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. ©2007 American Association for Cancer Research.Fil: Melana, Stella M.. University of Oklahoma Health Sciences Center; Estados UnidosFil: Nepomnaschy, Irene. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. University of Oklahoma Health Sciences Center; Estados UnidosFil: Sakalian, Michael. University of Oklahoma Health Sciences Center; Estados UnidosFil: Abbott, Andrea. University of Oklahoma Health Sciences Center; Estados UnidosFil: Hasa, Jennifer. University of Oklahoma Health Sciences Center; Estados UnidosFil: Holland, James F.. University of Oklahoma Health Sciences Center; Estados UnidosFil: Pogo, Beatriz G.T.. University of Oklahoma Health Sciences Center; Estados Unido

Detection of human mammary tumor virus proteins in human breast cancer cells

Mouse mammary tumor virus (MMTV) has been proven to induce mammary cancer in mice. MMTV-like env gene sequences have been detected in one-third of the human breast tumors studied. The whole proviral structure with 95% homology to MMTV was found in two human breast tumors and was designated as human mammary tumor virus (HMTV). HMTV viral particles with betaretroviral features have been isolated. In addition, a retrovirus called human betaretrovirus (HBRV), homologous to the mentioned retroviruses, has been isolated from tissues of patients with primary biliary cirrhosis. In this report, the expression of HMTV envelope (Env) and capsid (Ca) was detected in 10 primary cultures of human breast cancer containing HMTV sequences (MSSM) by Western blot and fluorescence activated cell sorting (FACS), using a panel of antibodies against HMTV Env, HBRV Env and Ca and the MMTV Env Gp36 and Ca P27 proteins. By contrast, HMTV proteins did not react with antibody against the MMTV Env Gp52 protein. All the antibodies detected MMTV proteins with exception of two out of four monoclonal antibodies against HMTV Env. Approximately 13% of the MSSM cells showed HMTV protein expression by FACS analysis. This report shows the expression of HMTV proteins for the first time in human breast cancer cells using a panel of antibodies against HMTV, HBRV and MMTV proteins. This should be taken into consideration when MMTV antibodies are used to detect HMTV proteins in human tissues. © 2009 Elsevier B.V. All rights reserved.Fil: Melana, Stella M.. Mount Sinai School of Medicine; Estados UnidosFil: Nepomnaschy, Irene. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Mount Sinai School of Medicine; Estados UnidosFil: Hasa, Jennifer. Mount Sinai School of Medicine; Estados UnidosFil: Djougarian, Alina. Mount Sinai School of Medicine; Estados UnidosFil: Djougarian, Anna. Mount Sinai School of Medicine; Estados UnidosFil: Holland, James F.. Mount Sinai School of Medicine; Estados UnidosFil: Pogo, Beatriz G.T.. Mount Sinai School of Medicine; Estados Unido

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 β-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. ©2007 American Association for Cancer Research.Fil: Melana, Stella M.. University of Oklahoma Health Sciences Center; Estados UnidosFil: Nepomnaschy, Irene. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. University of Oklahoma Health Sciences Center; Estados UnidosFil: Sakalian, Michael. University of Oklahoma Health Sciences Center; Estados UnidosFil: Abbott, Andrea. University of Oklahoma Health Sciences Center; Estados UnidosFil: Hasa, Jennifer. University of Oklahoma Health Sciences Center; Estados UnidosFil: Holland, James F.. University of Oklahoma Health Sciences Center; Estados UnidosFil: Pogo, Beatriz G.T.. University of Oklahoma Health Sciences Center; Estados Unido