CD44 expression in astrocytic tumors.

CD44 belongs to a family of adhesion molecules displayed by a wide range of normal and malignant cells. Several studies implicated its presence as a marker for poor prognosis or metastases, especially in breast and colon cancer. CD44 has been proposed as an invasion marker for glioblastoma. We studied 75 astrocytic tumors with different degrees of anaplasia including juvenile pilocytic astrocytoma (JPA), low-grade astrocytoma (LGA), anaplastic astrocytoma (AA), and glioblastoma multiforme (GBM) to determine whether standard CD44 (CD44s) can be used as a clinically useful marker distinguishing between low- and high-grade gliomas. Archival paraffin-embedded tissues from 19 JPAs, 20 LGAs, 17 AAs, and 19 GBMs were immunostained with standard CD44 monoclonal antibody and compared with glial fibrillary acidic protein, using the streptavidin-complex peroxidase technique. Immunostaining was rated on a three-tiered scale by two observers. The expression of variant-splice forms of CD44 (CD44v) have been variably reported in brain tumors; a subset of these gliomas were tested with anti-CD44v monoclonal antibodies. In the tumors studied, 89% of JPAs, 90% of LGAs, 76% of AAs, and 84% of GBMs have 2+ or 3+ intensity for CD44s. Low- and high-grade gliomas showed no significant difference in staining (P > .05). Therefore, CD44s does not seem to correlate with the grading range of astrocytomas. The overall intensity of CD44s immunostaining usually, but not always, showed concordance with glial fibrillary acidic protein immunostaining, but the distinctive membrane staining of CD44s surface staining revealed fine cytologic detail in tumor cell processes in diagnostic sections. Some very anaplastic tumors were negative for CD44s, and gliomas were immunonegative for CD44v6. If variant chains (CD44v) are not found in gliomas and if this large series of low- and high-grade gliomas show no difference in CD44 expression, other factors must be explored to understand the differential behavior of low- and high-grade astrocytomas.