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.

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.

Release of cell-free DNA into the bloodstream leads to high levels of non-tumor plasma DNA during tumor progression in rats.

To examine the implications of cell-free DNA in the plasma in neoplastic disease, it is necessary to clarify various features of this DNA, such as the contribution of DNA from the host's normal cells and the kinetics of the release of this latter DNA. To quantify non-tumor DNA in the plasma of tumor-bearing rats and to correlate levels of this DNA with tumor progression, we injected DHD/K12-PROb colon cancer cells subcutaneously into BD-IX rats and recorded tumor diameters weekly. After euthanasia, we collected plasma from each rat and quantified non-mutated and mutated DNA in the plasma.

Circulating nucleic acids in plasma/serum and tumor progression: are apoptotic bodies involved? An experimental study in a rat cancer model.

The "genometastasis hypothesis" proposes that cell-free tumor nucleic acids might be able to transform host stem cells, and that this might be a pathway for the development of metastases. This theory is supported by previous experimental findings and is consistent with observations of other authors. It has been suggested that tumor DNA might be horizontally transferred by the uptake of apoptotic bodies and initiate the genetic changes that are necessary for tumor formation.

Surgery and hematogenous dissemination: comparison between the detection of circulating tumor cells and of tumor DNA in plasma before and after tumor resection in rats.

Background: To examine the effects of the surgical manipulation of tumors on the hematogenous dissemination of tumors, we compared rates of detection of tumor-derived DNA in the buffy coat and in plasma from tumor-bearing rats before and after tumor resection.

Methods: We injected DHD/K12-PROb cells subcutaneously into BD-IX rats. Three weeks later, we removed the tumors surgically.