Until recently, the standard approach of most laboratories in distinguishing epithelioid pleural mesothelioma from metastatic adenocarcinoma has been a negative result from a panel of adenocarcinoma-associated antibodies. However, several "mesothelium-associated" antibodies have been proposed as useful in this situation, and we have applied four of these putative mesothelioma markers-thrombomodulin, cytokeratin 5/6, calretinin, and CD44H-to a series of 61 epithelioid pleural mesotheliomas and 63 metastatic adenocarcinomas with known primary sites (lung ‫؍‬ 19; breast ‫؍‬ 21; ovary ‫؍‬ 6; colon ‫؍‬ 10; kidney ‫؍‬ 4; uterus, epididymis, pancreas ‫؍‬ 1 case each). Of the mesotheliomas, 55 of 61 (90%) stained for thrombomodulin, 56 of 61 (92%) for cytokeratin 5/6, 47 of 51 cases (92%) were positive for calretinin, and 39 of 43 (91%) were positive for CD44H. Of the metastatic adenocarcinomas, 12 of 63 (19%) cases were positive for thrombomodulin, 9 of 63 (14%) were positive for CK5/6, and 27 of 60 (45%) were positive for CD44H. With calretinin, only 1 case of 59 (2%) showed positive nuclear staining. All four antibodies stained reactive mesothelium; thrombomodulin also stained endothelium; and CD44H variably stained lymphocytes, macrophages, and fibroblasts. We conclude that all four antibodies show high sensitivity for epithelioid mesothelioma, but only calretinin (98%), cytokeratin 5/6 (86%), and thrombomodulin (81%) show sufficient specificity for practical use in this situation.

This study shows levels of interobserver and intra-observer variation similar to those found in other grading systems in histopathology, with no significant decrease in variability found by abridging the system. The WHO/IASLC system is therefore recommended for future use in both clinical and research fields.

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The anti-inflammatory protein annexin A1 (ANXA1) has been associated with cancer progression and metastasis, suggesting its role in regulating tumor cell proliferation. We investigated the mechanism of ANXA1 interaction with formylated peptide receptor 2 (FPR2/ALX) in control, peritumoral and tumor larynx tissue samples from 20 patients, to quantitate the neutrophils and mast cells, and to evaluate the protein expression and co-localization of ANXA1/FPR2 in these inflammatory cells and laryngeal squamous cells by immunocytochemistry. In addition, we performed in vitro experiments to further investigate the functional role of ANXA1/FPR2 in the proliferation and metastasis of Hep-2 cells, a cell line from larynx epidermoid carcinoma, after treatment with ANXA12–26 (annexin A1 N-terminal-derived peptide), Boc2 (antagonist of FPR) and/or dexamethasone. Under these treatments, the level of Hep-2 cell proliferation, pro-inflammatory cytokines, ANXA1/FPR2 co-localization, and the prostaglandin signalling were analyzed using ELISA, immunocytochemistry and real-time PCR. An influx of neutrophils and degranulated mast cells was detected in tumor samples. In these inflammatory cells of peritumoral and tumor samples, ANXA1/FPR2 expression was markedly exacerbated, however, in laryngeal carcinoma cells, this expression was down-regulated. ANXA12–26 treatment reduced the proliferation of the Hep-2 cells, an effect that was blocked by Boc2, and up-regulated ANXA1/FPR2 expression. ANXA12–26 treatment also reduced the levels of pro-inflammatory cytokines and affected the expression of metalloproteinases and EP receptors, which are involved in the prostaglandin signalling. Overall, this study identified potential roles for the molecular mechanism of the ANXA1/FPR2 interaction in laryngeal cancer, including its relationship with the prostaglandin pathway, providing promising starting points for future research. ANXA1 may contribute to the regulation of tumor growth and metastasis through paracrine mechanisms that are mediated by FPR2/ALX. These data may lead to new biological targets for therapeutic intervention in human laryngeal cancer.

Annexin 1 protein (ANXA1) expression was evaluated in tumor and mast cells in human larynx cancer and control epithelium. The effect of the exogenous ANXA1 (peptide Ac 2-26) was also examined during the cellular growth of the Hep-2 human larynx epidermoid carcinoma cell line. This peptide inhibited the proliferation of the Hep-2 cells within 144 hr. In surgical tissue specimens from 20 patients with larynx cancer, ultrastructural immunocytochemistry analysis showed in vivo down-regulation of ANXA1 expression in the tumor and increased in mast cells and Hep-2 cells treated with peptide Ac2-26. Combined in vivo and in vitro analysis demonstrated that ANXA1 plays a regulatory role in laryngeal cancer cell growth. We believe that a better understanding of the regulatory mechanisms of ANXA1 in tumor and mast cells may lead to future biological targets for the therapeutic intervention of human larynx cancer. ' 2007 Wiley-Liss, Inc.