Tenascin-C expression relates to clinicopathological features in pilocytic and diffuse astrocytomas.

AIMS: Tenascin-C (TN-C) is an extracellular matrix brain glycoprotein for which conflicting in vitro and in vivo results are reported in the literature dealing with its involvement in astrocytoma aggressiveness, in particular astrocytoma invasion. In view of these conflicting results and the lack of data available on low-grade astrocytomas, the present study focuses on pilocytic World Health Organization (WHO) grade I, and diffuse WHO grade II astrocytomas, that is, two histological entities associated with very different invasive abilities. METHODS: Using real-time reverse transcription polymerase chain reaction and immunohistochemistry, we analysed the TN-C expression in normal brain tissue as well as in a series of 54 pilocytic and 53 grade II astrocytomas. CONCLUSIONS: Our data on normal brain showed that while TN-C is largely expressed in supratentorial white matter, it was largely absent in infratentorial white matter. Paralleling these observations, we showed that TN-C expression in low-grade astrocytomas similarly varies according to tumour site. Cox regression analysis evidenced that TN-C provided an independent prognostic value which is enhanced in the case of grade II astrocytomas for which positive TN-C expression is associated with a higher risk of recurrence. We also analysed TN-C expression specifically in vascular areas of low-grade astrocytomas without demonstrating any prognostic value for this additional feature. RESULTS: Similarly to normal brain, low-grade astrocytomas exhibit variations in TN-C expression with site, and this expression is associated with an independent prognostic value in terms of recurrence.

The differential expression of Galectin-1 and Galectin-3 in normal lymphoid tissue and non-Hodgkin's and Hodgkin's lymphomas.

The WHO classification of lymphomas was established on the basis of clinical, morphological, immunohistochemical and genetic criteria. However, each entity displays its own spectrum of clinical aggressiveness. Treatment success varies widely and is not predictable. Since galectins are involved in oncogenesis and the physiology of immune cells, we investigated whether galectin-1 and galectin-3 immunohistochemical expression could differ in 25 normal lymphoid tissues, 42 non-Hodgkins and 14 Hodgkins lymphomas. Immunohistochemical galectin expression was submitted to semi-quantitative and quantitative (computer-assisted microscopy) evaluations. This study is completed by an analysis (by means of quantitative RT-PCR) of galectin-3 mRNA expression in 3 normal lymph nodes, 3 follicular lymphomas (FLs) and 3 diffuse large B-cell lymphomas (DLBCLs). The data show that in normal lymphoid tissue, lymphocytes do not express galectin-1 and rarely express galectin-3. In contrast, galectin-3 was expressed in 8 of the 16 DLBCL cases and in 1 of the 8 FL cases. Furthermore, galectin-3 mRNA was expressed 3 times more in the DLBCLs than in the FLs. While the blood vessel walls of the lymphomas expressed galectin-1, the vessel walls of normal lymphoid tissues did not. This expression of galectin-1 in blood vessel walls was correlated with vascular density. The present study thus shows that DLBCL can be distinguished from normal lymphoid tissue and other lymphomas on the basis of galectin-3 expression.