KAI1 IS UNCHANGED IN METASTATIC AND NONMETASTATIC ESOPHAGEAL AND GASTRIC CANCERS

Down-regulation of KAI1 mRNA expression has been shown to be associate d with the formation of metastases or disease progression in pancreati c cancer, Whether KAI1 possesses similar characteristics in other mali gnancies of the gastrointestinal tract is not known. Here, we compared the patterns of KAI1 mRNA expression in 41 esophageal cancers and 35 stomach cancers to assess whether KAI1 might also be of biological rel evance in the metastatic ability of these tumors. By Northern blot ana lysis, KAI1 mRNA levels ranged widely in both normal and cancerous eso phageal and gastric tissue samples, with no statistical differences, N o association between KAI1 mRNA expression and tumor stage or tumor di fferentiation was seen in these tumors. In addition, KAI1 mRNA express ion was similar in primary esophageal and gastric cancer samples with or without metastases. By in situ hybridization, KAI1 mRNA expression was evident in the cytoplasm of most squamous epithelial cells in the normal esophagus and in nonmucosal epithelial cells of the normal stom ach, The staining intensity in the esophageal and gastric cancer cells was similar to that in the normal controls. This differential pattern of KAI1 mRNA expression in esophageal and gastric cancers in comparis on to pancreatic cancer indicates that KAI1 seems to influence the pot ential of gastrointestinal cancer cells to metastasize differently, In esophageal and gastric cancers, the formation of metastases is not de pendent on the reduction of KAI1 in the cancer cells.