Monocyte chemoattractant protein-1 (MCP-1) expression in primary lymphoepithelioma-like carcinomas (LELCs) of the lung

Lymphoepithelioma-like carcinoma (LELC) of the lung is a recently recognize d primary non-small cell lung carcinoma with distinct clinicopathological f eatures and an aetiological association with Epstein-Barr virus (EBV) infec tion. The tumour consists of clusters and sheets of poorly or undifferentia ted tumour cells in close association with numerous mononuclear inflammator y cells, including a rich component of tumour-associated macrophages (TAMs) . To investigate the molecular mechanism leading to the TAM-rich stroma, th e expression of a monocyte-specific chemotactic and activating factor, mono cyte chemoattractant protein-1 (MCP-1), was studied by reverse transcriptas e-polymerase chain reaction (RT-PCR) and in situ hybridization (ISH), and t he presence of TAMs was demonstrated by immunohistochemistry in nine LELCs. The results were compared with those found in 17 conventional non-small ce ll lung carcinomas. RT-PCR showed specific MCP-1 amplification in both LELC s and non-LELCs, but ISH demonstrated a unique and extensive expression of MCP-1 transcripts by the tumour cells of LELCs only, while TAMs, stromal fi broblasts, and endothelial cells formed the major source of MCP-1 in non-LE LCs, TAMs in LELCs were more abundant and showed a close topographical rela tionship with the MCP-1-expressing tumour cells. The results indicate that tumour cell expression of MCP-1 in LELCs is an important mechanism contribu ting to their distinctive morphological features. This is the first study t hat demonstrates the in Fire upregulation of a monocyte-specific chemokine by EBV-related carcinomas, illustrating an interesting aspect of tumour bio logy in EBV-related neoplasms. (C) 1998 John Wiley & Sons, Ltd.