Establishment and characterization of new mammary adenocarcinoma cell lines derived from double transgenic mice expressing GFP and neu oncogene.

A new murine cell line, named GFPneu, was established from a mammary adenocarcinoma arising in double transgenic MMTVneu x CMV-GFP mice. Breast tumours develop in 100% of females after 2 months latency, as a result of the over-expression of the activated rat neu oncogene in the mammary glands. All tissues, and in particular the breast tumours, express the GFP protein. This cell line was tumorigenic when inoculated into nude mice and the derived tumours showed the same histological features as the primaries from which they were isolated. Their histopathology reproduces many characteristics of human breast adenocarcinomas, in particular their ability to metastasize. The GFP marker allows us to visualize the presence of lung metastases in fresh tissues immediately, to confirm the histopathology. From a lung metastatic fluorescent nodule, we derived a further cell line, named MTP-GFP, which we also characterized. These two cell lines could be useful to study the role played by the neu oncogene in the maintenance of the transformed phenotype, in the metastatic process, to test novel therapeutic strategies to inhibit primary tumour growth and to observe the generation of distant metastases.