title: Loss of KAI1 expression in the progression of colorectal cancer.
abstract: The transmembrane 4 superfamily member KAI1 (CD82) has been shown to inhibit pulmonary metastases in experimental metastasis models of prostate cancer and melanoma. KAI1 expression is decreased in the progression of common solid epithelial tumors of adulthood, including lung, prostate, breast, esophageal, gastric, pancreatic, and bladder cancers. The purpose of our study was to investigate KAI1 expression in the progression of human colorectal cancer. We first analyzed 20 colorectal cancer cell lines by immunoblot techniques. KAI1 was expressed heterogeneously, with the tumor cell lines having a more complex degree of glycosylation compared with that of the normal colonic tissue. KAI1 was highly expressed in the primary SW480 colon cancer cell line but was down-regulated 15-fold in the matched metastatic SW620 cell line. We also investigated KAI1 protein expression by immunohistochemistry in tissues from 84 patients with colorectal cancer. Each tissue section was assigned a KAI1 mean score (KMS) from 0 to 300 based on the product of the percentage of cells that stained for KAI1 and the intensity of the stain (1, 2, or 3). In 84 patients with colorectal cancer, KAI1 was expressed at high levels in normal colonic mucosa (KMS 226) but was expressed at lower levels in the primary tumors (KMS 65; P < 0.0001). In a subset of 12 patients with stage IV metastatic disease, we observed a progressive down-regulation of KAI1, from the normal adjacent colonic mucosa (KMS 193) to the primary tumor (KMS 72; P = 0.0001) to the liver metastasis (KMS 25; tumor compared with metastasis, P = 0.0135). We found no correlation between loss of KAI1 expression and stage of disease. In 10 patients, we also noted loss of KAI1 expression in the transition from normal colonic mucosa (KMS 237) to adenoma (KMS 174) to carcinoma (KMS 62; P < 0.0167 for all three comparisons). We conclude that the down-regulation of KAI1 occurs early in the progression of colorectal cancer.
authors.affiliation: Laboratory of Molecular Carcinogenesis, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709, USA.
authors.forename: D P
authors.initials: DP
authors.lastname: Lombardi
authors.forename: J
authors.initials: J
authors.lastname: Geradts
authors.forename: J F
authors.initials: JF
authors.lastname: Foley
authors.forename: C
authors.initials: C
authors.lastname: Chiao
authors.forename: P W
authors.initials: PW
authors.lastname: Lamb
authors.forename: J C
authors.initials: JC
authors.lastname: Barrett
mesh_terms: D000236:Adenoma / Q000378:metabolism; D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D015703:Antigens, CD / Q000737:chemistry / Q000378:metabolism*; D002277:Carcinoma / Q000378:metabolism; D002448:Cell Adhesion; D003106:Colon / Q000378:metabolism*; D003110:Colonic Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D004260:DNA Repair; D018450:Disease Progression; D015536:Down-Regulation; D005260:Female; D016158:Genes, p53 / Q000235:genetics; D005838:Genotype; D006801:Humans; D051861:Kangai-1 Protein; D008113:Liver Neoplasms / Q000378:metabolism / Q000556:secondary; D008297:Male; D008562:Membrane Glycoproteins / Q000737:chemistry / Q000378:metabolism*; D008875:Middle Aged; D008970:Molecular Weight; D009363:Neoplasm Proteins / Q000737:chemistry / Q000378:metabolism*; D009367:Neoplasm Staging; D011518:Proto-Oncogene Proteins; D012004:Rectal Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D014407:Tumor Cells, Cultured
chemical_list: D015703:Antigens, CD; C497688:CD82 protein, human; D051861:Kangai-1 Protein; D008562:Membrane Glycoproteins; D009363:Neoplasm Proteins; D011518:Proto-Oncogene Proteins