Immortalized Mouse Mammary Fibroblasts Lacking Dioxin Receptor Have Impaired Tumorigenicity in a Subcutaneous Mouse Xenograft Model

• Published in: The Journal of biological chemistry Vol. 280; no. 31; pp. 28731 - 28741
• Main Authors: Mulero-Navarro, Sonia, Pozo-Guisado, Eulalia, Perez-Mancera, Pedro A, Alvarez-Barrientos, Alberto, Catalina-Fernandez, Inmaculada, Hernandez-Nieto, Emilia, Saenz-Santamaria, Javier, Martinez, Natalia, Rojas, Jose M, Sanchez-Garcia, Isidro, Fernandez-Salguero, Pedro M
• Format: Journal Article
• Language: English
• Published: United States American Society for Biochemistry and Molecular Biology 05.08.2005
• Subjects: Animals; Antigens, Polyomavirus Transforming - genetics; Cell Cycle; Cell Division; Fibroblasts - cytology; Fibroblasts - physiology; Genes, ras; Leiomyosarcoma - prevention & control; Mammary Glands, Animal - cytology; Mice; Mice, Knockout; Mice, SCID; Receptors, Aryl Hydrocarbon - deficiency; Receptors, Aryl Hydrocarbon - genetics; Skin Neoplasms - prevention & control; Skin Transplantation - pathology; Transfection; Transplantation, Heterologous
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M504538200

Although the dioxin receptor, the aryl hydrocarbon receptor (AhR), is considered a major regulator of xenobiotic-induced carcinogenesis, its role in tumor formation in the absence of xenobiotics is still largely unknown. Trying to address this question, we have produced immortalized cell lines from wild-type (T-FGM-AhR+/+) and mutant (T-FGM-AhR-/-) mouse mammary fibroblasts by stable co-transfection with the simian virus 40 (SV-40) large T antigen and proto-oncogenic c-H-Ras. Both cell lines had a myofibroblast phenotype and similar proliferation, doubling time, SV-40 and c-H-Ras expression and activity, and cell cycle distribution. AhR+/+ and AhR-/- cells were also equally able to support growth factor- and anchorage-independent proliferation. However, the ability of T-FGM-AhR-/- to induce subcutaneous tumors (leimyosarcomas) in NOD/SCID-immunodeficient mice was close to 4-fold lower than T-FGM-AhR+/+. In culture, T-FGM-AhR-/- had diminished migration in collagen-I and decreased lamellipodia formation. VEGFR-1/Flt-1, a VEGF receptor that regulates cell migration and blood vessel formation, was also down-regulated in AhR-/- cells. Signaling through the ERK-FAK-PKB/AKT-Rac-1 pathway, which contributes to cell motility and invasion, was also significantly inhibited in T-FGM-AhR-/-. Thus, the lower tumorigenic potential of T-FGM-AhR-/- could result from a compromised adaptability of these cells to the in vivo microenvironment, possibly because of an impaired ability to migrate and to respond to angiogenesis.