Total protein and DNA extracted from histologically diagnosed normal
nonmalignant and esophageal tumor tissues were used for analysis of polypeptides
pattern by two-dimensional gel electrophoresis and DNA transforming activity in
NIH 3T3 cell transfection assay, respectively. In comparison to normal tissues, eight
polypeptides underwent down-regulation or disappeared, while seven polypeptides
were subjected to up-regulation or appeared for the first time in tumor tissues. We
suggest that the first eight polypeptides are necessary for maintenance of normal
phenotype and the other seven polypeptides are involved in the development of
malignant phenotype. However, results obtained from NIH 3T3 cell transfection with
esophageal tumorous DNA showed that such DNAs lack transforming efficiency.
These data may agree with the published reports about the absence of activated
transforming oncogenes such as the ras family in esophageal cancer specimens