Gradual expression of MMP9 and MT1-MMP at the tumor-stroma interface in head and neck squamous cell carcinoma

Due to the late-stage diagnosis of head and neck squamous cell carcinoma (HNSCC), treatment remains a significant clinical challenge. The metalloproteinases MMP-9 and MT1-MMP play a pivotal role in extracellular matrix remodeling, thereby facilitating tumor growth and metastasis. Tumor progression requires the degradation of the basement membrane. The principal components of this structure, namely collagen IV and laminin, are the main targets of both MMP-9 and MT1-MMP. However, they can also exert influence over the expression of these enzymes. Oxidative stress plays an instrumental role in tumor development, functioning as a key inducer of metalloproteinase expression. The present study investigates the distribution of MMP-9 and MT1-MMP within tumor nests and along the basement membrane, comparing these with the distributions of collagen IV, laminin-332, and the antioxidant MnSOD. Biopsies from 12 patients with HNSCC and poor prognostic factors were subjected to immunofluorescence analysis. MMP-9 and MT1-MMP were found to be predominantly present in tumor cells, with a significant decrease in expression from the periphery to the center of tumor nests. Co-localization studies with laminin-332 and collagen IV, revealed substantial overlap, in accordance with the role of MMPs in basal membrane degradation. The cellular expression of laminin-332 associated with MMP-9 expression suggests an intricate relationship between metalloproteinases and their targets. While the previously observed pattern of glutathione-producing enzyme was similar to the metalloproteinases pattern, MnSOD expression was homogeneously distributed within tumor nests. Our findings reveal various distribution patterns of oxidative stress regulators, suggesting a complicated interplay in the development of HNSCC.