HISTOLOGY AND HISTOPATHOLOGY

Cellular and Molecular Biology

 

Loss of a reporter gene for green fluorescent protein during tumor progression suggests the recruitment of host cells in rats with experimentally induced colon cancer

Dolores C. García-Olmo1, Julia Samos1, María G. Picazo1, Gemma Fernández-Miguel2, Inmaculada Toboso1 and Damián García-Olmo3

1Experimental Research Unit, General University Hospital of Albacete, Albacete, Spain, 2Cellerix S.L., Parque Tecnológico de Madrid, Tres Cantos, Madrid, Spain and 3Department of Surgery, Universidad Autónoma de Madrid and La Paz University Hospital, Madrid, Spain.

Offprint requests to: Dr. Dolores C. García-Olmo, Unidad de Investigación, Hospital General Universitario de Albacete, 02006 Albacete, Spain. e-mail: doloresg@sescam.jccm.es


Summary. The interactions between a host’s normal cells and tumor cells appear to be of significant importance during the development of tumors. In the present study, we examined this issue using a cancer model in vivo in which tumor cells were tagged with a reporter gene for green fluorescent protein (GFP). We used a model of colon cancer in immunocompetent rats, which were given a subcutaneous injection of tumor cells that had been transfected with a gene for GFP. We found that the number of fluorescent cells decreased with the progression of the primary tumors and that lymph node and lung metastases were never macroscopically fluorescent. No GFP-encoding sequences were detected by PCR in many of the long-term primary tumors, in most lymph node metastases (86%) and in all lung metastases, whereas the detection of mutated k-ras, which identified such cells as tumor cells, was always positive. To explain these findings, we present a brief review of the literature and postulate that tumor growth did not occur exclusively as a result of the division of the injected cells, but also involved recruitment of host cells. Histol Histopathol 23, 1205-1211 (2008)

Key words: Green fluorescent protein, Cancer, Metastasis, Immunocompetent rat

DOI: 10.14670/HH-23.1205