Gene Expression for Tumor Necrosis Factor a and Its Production in Gastric Cancer Patients

To determine the gene expression for tumor necrosis factor (TNF) a and its main site of production in gastric cancer patients, serum levels in the peripheral venous blood of 50 patients and the portal blood from 15 of these 50 patients were measured by enzyme‐linked immunosorbent assay (ELISA). TNF gene expression in the peripheral blood mononuclear cells (PBMC) and in the surgically resected tissues was then studied in 16 patients by reverse transcription‐polymerase chain reaction (RT‐PCR) assay. Whereas TNF mRNA expression was detected in the PBMC from 13 of 16 gastric cancer patients (81.3%), it was detected in only one tumor tissue (6.3%). Preoperatively, TNF was detected in the serum from 13 of 50 patients (26.0%). In the portal blood sampled immediately after laparotomy, TNF was positive in 4 of 15 patients (26.7%). TNF gene expression was much more frequently detected in PBMC than in other resected tissues, and its expression was higher than in the serum. Various clinicopathological factors for gastric cancer were not related to the prcopcrative detection of TNF in the serum. It appears that TNF is produced mainly in PBMC but not in the cancer regions or the regional lymph nodes of gastric cancer patients. It is suggested that TNF is not always secreted even when TNF mRNA is expressed, and its preoperatlve production is not related to tumor progression.