M. B. Burch1, J. M. Warram1, N. G. Patel1, T. M. Zimmermann2, E. L. Rosenthal1 1University Of Alabama At Birmingham,Division Of Otolaryngology, Department Of Surgery,Birmingham, AL, USA 2Mayo Clinic,Department Of Otorhinolaryngology,Rochester, MN, USA
Introduction:
S100A9, a subunit of the protein calprotectin, is released during tissue damage and has been implicated in the progression of inflammation and cancer metastasis. Recent studies suggest that extracellular matrix metalloproteinase inducer (EMMPRIN) can act as a cell-surface receptor for S100A9. EMMPRIN is a well-characterized factor in the progression of many head and neck tumors. Therefore, evidence of an S100A9-EMMPRIN interaction would serve to further demonstrate a possible role for S100A9 in local tumor invasion and disease progression.
Methods:
Human SCC1-Luc+ HNSCC cells were injected into the unilateral flank of nude athymic mice. Tumors were grown for 1 week before exposure to trial compounds. Studies incorporated exposure of these tumors to the S100A9 inhibitor Tasquinimod (TASQ) via drinking water at a dose of 10 mg/kg/day, as well as anti-EMMPRIN monoclonal antibody (CNTO3899). Groups included exposure to TASQ (n=5), anti-EMMPRIN (n=5), TASQ + anti-EMMPRIN concurrently (n=5), and untreated (n=5). Microcalipers and bioluminescence imaging via luciferase were used to quantify tumor size. Tumors were resected, sectioned, and mounted. Immunohistochemistry was performed using primary antibodies to EMMPRIN and S100A9. Corresponding fluorescently-labeled secondary antibodies and fluorescence microscopy were used to assess localized expression. Scores were assigned descriptively using a modified Allred scoring method by assigning a relative expression of 0 to 5 based on fluorescence intensity and 0 to 5 based on fluorescence distribution within each sample. Aggregated scores were then used for statistical analysis.
Results:
Upon study termination, tumors exposed to TASQ alone and exposed to TASQ + anti-EMMPRIN were significantly larger than untreated tumors (p= 0.015 and p=0.009, respectively). In vivo analysis revealed that mice administered TASQ alone exhibited an increase in tumor size 110.77% over untreated tumors, whereas tumors exposed to both TASQ and anti-EMMPRIN concurrently demonstrated a 113.04% increase in tumor size over untreated tumors during this same period. Tumors exposed only to anti-EMMPRIN decreased 78.26% in size compared to untreated tumors. Tumors exposed to TASQ demonstrated a significant decrease in EMMPRIN expression compared to untreated tumors (p=0.015).
Conclusion:
Inhibition of S100A9 activity by TASQ in HNSCC leads to accelerated tumor growth, suggesting a possible protective role for this molecule in squamous cell tumors. The concurrent inhibition of S100A9 and EMMPRIN contributes to enhanced disease progression in HNSCC. Inhibition of EMMPRIN alone decreases HNSCC progression. Inhibition of S100A9 by TASQ leads to a significant decrease in cellular EMMPRIN expression.
