Proliferation of gastrointestinal carcinoma cells by T lymphocyte factors interleukin-3 and granulocyte-macrophage colony-stimulating factor.

Hematopoietic growth factors have been well characterized by cDNA cloning in recent years. In order to determine the influence of rhGM-CSF and rhIL-3 on epithelial cells of the gastrointestinal tract, their influence on in vitro cultured gastric and pancreas cancer cells was determined. A more than two-fold enhancement of proliferation was observed by IL-3 and GM-CSF in Mz-Sto-1 gastric and 818-4 pancreas carcinoma cells, applying a sensitive microculture system which allows precise quantification. The highest growth rates were obtained adding 1-10 ng/ml of the growth factors, but even picogram amounts were effective. Expression of mRNA for GM-CSF and IL-3 remained undetectable in the cell lines, but mRNA for the EGF receptor was demonstrated. However, IL-3 and GM-CSF did not up-regulate mRNA for the EGF receptor. Therefore, the hematopoietic growth factors IL-3 and GM-CSF stimulate proliferation of epithelial cells derived from gastric and pancreas carcinomas by a paracrine mechanism. This effect did not involve an up-regulation of EGF receptor mRNA.