Up-regulated expression of the uridine phosphorylase gene in human gastric tumors is correlated with a favorable prognosis.

Uridine phosphorylase (UP) is one of the enzymes involved in 5-fluorouracil (5-FU) activation. The expression was compared in paired specimens from cancerous and non-cancerous regions of gastric, colon and lung cancer patients. Among 28 paired gastric samples, 20 cases showed greater expression in tumors than in normal surrounding tissues and 8 cases showed equal or lower expression levels in tumors. All the gastric patients received 5-FU before and/or after the surgical resection and the prognosis of the patients, whose UP tumor expression increased, was relatively better than that of the patients with equal or less UP gene tumor expression. In contrast, most of the colon (22 cases in total) and all the lung cancer patients (14 in total) did not receive 5-FU and the majority of the colon (12 cases) and lung (10 cases) specimens showed lower expression in the cancerous region. The differential expression between cancerous and non-cancerous regions in colon and lung cancers was not linked with the prognosis. These data suggest that the paired expression level of the UP gene in gastric cancer is a possible prognostic marker for the patients who received 5-FU.