PSA is an oncodevelopmental
antigen usually expressed in human
tumors with high metastatic potential. Here we set up a metastatic model in nude mice by using TE671 cells, which strongly express
PSA-NCAM. We observed the formation of lung
metastases when TE671 cells were injected intravenously, intramuscularly, and intraperitoneally, but not subcutaneously.
Intraperitoneal injections also induced peritoneal carcinosis,
ascites, and liver
metastases. To evaluate the putative role of PSA in the metastatic process we used a specific cleavage of PSA on
NCAM by
endoneuraminidase-N on intraperitoneal primary
tumors. Mice with primary intramuscular
tumors were taken as control. Repeated
injections of
endoneuraminidase-N led to a decrease in PSA expression in primary intraperitoneal nodules and
ascites but not in intramuscular primary
tumors.
Endoneuraminidase-N also increased the delay in ascitic formation and decreased the number of lung or liver
metastases in the case of intraperitoneal
tumors but not in the case of intramuscular
tumors. When
metastases occurred in
endoneuraminidase-N injected animals, they strongly expressed
PSA-NCAM. Therefore, we established a relationship between PSA expression on the surface of primary
tumor cells and the metastatic process.