Mammaglobin B gene as a novel marker for lymph node micrometastasis in patients with abdominal cancers

Mammaglobin B is a recently-isolated gene speculated to belong to the utero globin gene family and is overexpressed in primary breast cancers. We inves tigated mammaglobin B mRNA expression in various cancers of the digestive s ystem. Given the absence of mammaglobin B expression in normal lymph nodes, we also assessed the usefulness of mammaglobin B as a marker for lymph nod e micrometastases in cancer patients. Mammaglobin B gene transcripts were f requently detected by reverse transcriptase-polymerase chain reaction (RT-P CR) assay in primary tumors of the esophagus (2/3), stomach (7/7), colon (1 5/15), pancreas (4/6), common bile duct (6/6), cholangioma (2/2) and gall b ladder (1/1). Mammaglobin B overexpression was observed in three of 15 case s (20%) of colon cancer, suggesting its possible contribution to colon carc inogenesis. Downregulated mammaglobin B expression was observed in hepatoma cells in comparison with corresponding non-cancerous livers (3/3). RT-PCR assay of mammaglobin B detected 14 of 15 histologically positive lymph node s from patients with gastric cancer, colon cancer and cholangioma. Seven of 32 (22%), three of nine (33%), and three of seven (43%) histologically neg ative nodes from patients with gastric, colon and cholangiocellular carcino ma, respectively, were found to express mammaglobin B mRNA. Our results sho wed that expression of mammaglobin B was frequently detected in cancers ori ginating in digestive organs, especially adenocarcinomas, and that mammaglo bin B gene detected by RT-PCR may be a potentially useful molecular marker for lymph node micrometastases of various digestive organ cancers. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.