RAS MUTATION AND EXPRESSION OF THE RAS-REGULATED GENES OSTEOPONTIN AND CATHEPSIN-L IN HUMAN ESOPHAGEAL CANCER

As part of our ongoing studies to characterize molecular alterations i n a well-defined series of surgically resected esophageal cancers, we examined the expression of 2 ras-regulated genes, whose products (oste opontin and cathepsin L) previously were shown;to be associated with t umor invasion and metastasis. RNA was extracted from primary esophagea l tumors (adenocarcinomas, 19; squamous-cell carcinomas, 6) and matche d histologically normal esophageal mucosa from the distant resection m argin. Northern analysis was used to quantitate RNA, relative to an 18 S rRNA control, and immunohistochemistry to assess the tissue distribu tion of osteopontin. In addition, H-, K- and N-ras mutations were stud ied in the same tissues using PCR and hybridization with allele (mutan t)-specific oligonucleotide probes. We demonstrated a K-ras mutation ( codon 12, GTT) in one esophageal adenocarcinoma. The res-regulated gen e osteopontin was over-expressed in 100% of squamous-cell carcinomas a nd in 58% of adenocarcinomas relative to matched normal esophageal muc osa. Patterns of immunoreactivity for osteopontin protein also varied between squamous-cell carcinomas (tumor cell staining) and adenocarcin omas (predominantly tumor-infiltrating macrophages). Expression of cat hepsin L also varied with esophageal tumor histology, with over-expres sion in 58% of primary esophageal adenocarcinomas and 33% of squamous- cell cancers. (C) 1997 Wiley-Liss, Inc.