L1 cell adhesion molecule (CD171) represents a strongly unfavorable prognostic biomarker for ovarian and endometrial carcinomas. Here we carried out an immunohistochemical survey of L1 expression in normal adults and in a broad range of benign and malignant tumors using monoclonal antibody L1-11A and the novel monoclonal antibody L1-14.10. In normal tissues, L1 was expressed in the collecting tubules of adult tissues and pediatric kidney and in peripheral nerve bundles. In tumors of the female genital tract, L 1 was detected in adenocarcinomas of the cervix and fallopian tubes, in addition to ovarian and endometrial carcinomas. Nongynecological tumors expressing L1 comprised malignant melanoma, colon adenocarcinoma positive to chromogranin, clear-cell adenocarcinoma of the urinary bladder, pheochromocytoma, small cell lung carcinoma, and tumors of the nervous system. L1 was absent in breast carcinoma, gastrointestinal tract carcinomas, gastrointestinal carcinoids, renal clear-cell carcinomas, prostate adenocarcinomas, and mesotheliomas. Surprisingly, L1 expression in established breast and renal carcinoma cell lines was not a predictor for its presence in these human tumors in vivo. Our results suggest that L1 expression in tumors is not ubiquitous but restricted to certain subtypes and may be a helpful molecular marker for differential diagnosis and target for antibody-based therapy. (c) 2006 Elsevier Inc. All rights reserved.
