Distribution pattern of tenascin-C in glioblastoma: correlation with angiogenesis and tumor cell proliferation

Tenascin-C (TN-C) is an extracellular matrix protein which participates in different processes like normal fetal development, wound healing, inflammation, keloids and rheumatoid arthritis. Furthermore, the immunostaining for TN-C is seen in the stroma of various malignant tumors as in glioblastoma multiforme (GBM), however, the significance of these findings is still not clear. In this study 62 GBM samples were analyzed immunohistochemically for distribution patterns of TN-C and correlated with angiogenesis and tumor cell proliferation. Tenascin-C in GBM localizes in two compartments, perivascular and intercellular space. Intercellular tenascin-C (TN-C ic) showed focal distribution in 66%, and diffuse one in 34% of cases. Perivascular tenascin-C (TN-C pv) showed strong correlation with microvascular density (MVD) and vascular endothelial growth factor (VEGF) expression. Moreover, it seems that TN-C pv enhanced the effect of VEGF. Intercellular TN-C did not correlate with MVD and VEGF expression, but showed strong correlation with proliferation index. Furthermore, tumors with diffuse TN-C ic expression had higher proliferation indices than tumors with focal TN-C expression. Our results indicate that TN-C plays a role in angiogenesis and tumor cell proliferation, but beside the intensity of expression, the distribution patterns are also important in these processes. This study also suggests that perivascular and intercellular TN-C compartments have probably different sources and different roles in GBM.