Localization by in situ hybridization of mRNAs encoding stromelysin 3 and tissue inhibitors of metallo-proteinases TIMP-1 and TIMP-2 in human head and neck carcinomas.

The presence and distribution of mRNAs encoding a matrix metalloproteinase (MMP) stromelysin 3 and two tissue inhibitors of MMP, TIMP1 and TIMP-2 have been studied by in situ hybridization of 18 human epidermoid head and neck carcinomas and four normal tissues. We found that in 16 tumors out of 18, stromelysin 3 mRNAs were only expressed by fibroblasts which were in close contact to invasive cancer cells. Tumor cells and normal tissues were not labeled. TIMP-1 mRNAs were detected in well differentiated cancer cells and in endothelial cells in all the cancers. In 13 out of the 18 carcinomas, TIMP-2 mRNAs were localized in only a few stromal cells near well differentiated invasive cancer cells and in endothelial cells. The significant expression of TIMP-1 and TIMP-2 mRNAS may lead to less aggressive MMPs, especially in the case of stromelysin 3, in the invasive process of the stroma.