Characterization of mast cell subpopulations in lip cancer

BACKGROUND: Lip squamous cell carcinoma (SCC) is the most common form of oral cancer. Human mast cells (MCs), which are increased in up SCC, are classified by their protease content in tryptase-positive (MC_T) and tryptase/chymase-positive (MC_TC). MC proteases are associated with tumor progression and angiogenesis. The aim of this study was to quantify and characterize MC subpopulations in lip SCC. METHODS: Serial sections from lip SCC (n = 21) and normal lip vermilion (n = 8) biopsies were stained immunohistochemically for tryptase and enzymehistochemically for chymase to determine MC subpopulation density and distribution. RESULTS: MC_T and HC_TC were increased in lip SCC when compared with normal lip (P < 0.0001), where MC_T predominated over MC_TC (P < 0.01). In lip SCC neither subpopulation predominated. Regarding distribution, MC _T were higher than MC_TC at the intratumoral stroma, whereas MC_TC were higher than MC_T at the peritumoral stroma (P < 0.01). CONCLUSIONS: The results suggest that MC subpopulations may contribute to lip SCC progression. While intratumoral MC_T may stimulate angiogenesis, peritumoral MC_TC may promote extracellular matrix degradation and tumor progression at the invasion front.