Regional difference in intratumoral lymphangiogenesis of oral squamous cell carcinomas evaluated by immunohistochemistry using D2-40 and podoplanin antibody: an analysis in comparison with angiogenesis.

Background:  Whether tumor cells induce lymphangiogenesis intratumorally or permeate pre-existing lymphatic vessels in the peritumoral area still remains unclear. In this study, we investigated in detail the intratumoral lymphangiogenesis of oral squamous cell carcinomas (SCC) in comparison with tumor angiogenesis. Methods:  Immunohistochemistry with D2-40, podoplanin antibody, and CD34 antibody were used to evaluate the lymphatic vessel density (LVD) and blood microvessel density (MVD). Vascular endothelial growth factor (VEGF) and VEGF-C expressions of oral SCC were also assessed by immunohistochemistry. Results:  LVD significantly increased in the superficial area of tumor tissue compared with normal mucosa, whereas it decreased in the deep area of intratumoral tissue near the invasion front, in sharp contrast to MVD, which significantly increased throughout tumor tissue. Consistent with the decreased intratumoral LVD and increased intratumoral MVD, VEGF-C expression of tumor cells was down-regulated in the deep area of tumor tissue, while VEGF expression of tumor cells was up-regulated throughout the tumor tissue. Conclusions:  Lymphangiogenesis in oral SCC varies depending on the region within the tumor tissue. It is not induced in the genuine tumor stroma near the invasion front, probably due to the down-regulation of VEGF-C expression of tumor cells, which is different from VEGF-mediated induction of intratumoral angiogenesis.