Prohormone convertase furin has a role in gastric cancer cell proliferation with parathyroid hormone-related peptide in a reciprocal manner.

We investigated the expression of parathyroid hormone-related peptide (PTHrP) and the relationship between PTHrP and its endoprotease furin in gastric cancer. PTHrP was colocalized with furin in 75% of gastric cancer tissues (six of eight) from patients with high serum PTHrP levels. PTHrP mRNA expression was confirmed in 67% of gastric cancer cell lines (four of six), whereas furin mRNA was detected in all six gastric cancer cell lines. In a cultured gastric cancer cell line, MKN28, mature PTHrP protein expression was markedly increased by transfection of furin cDNA. Furin cDNA-transfected MKN28 cells grew faster than did the mock controls. Moreover, furin mRNA expression in cultured gastric cancer cells was enhanced when PTHrP was added to the culture medium. These results suggest a link between PTHrP and furin in the regulation of gastric cancer cell growth. Furin might be involved not only in the production of the mature form of PTHrP, but also in promoting growth in gastric cancer cells.