Expression patterns of insulin-like growth factor binding protein isoforms in medulloblastoma subtypes and clinical correlation.

Background: Insulin-like growth factor binding proteins (IGFBPs) are known to be differentially expressed in brain tumours. The role of some IGFBPs in malignant CNS tumours, except glioblastoma, is unknown. We evaluated the protein expression of 3 IGFBP isoforms (IGFBP-2, -3, -5) in medulloblastoma and correlated them with histological subtypes and clinical parameters.

Methods: The expression of IGFBP-2, -3 and -5 was analysed in 67 samples of medulloblastoma by immunohistochemistry and correlated with histological subtypes and patient prognosis.

Results: IGFBP-3 expression was seen in 37.3% of cases and IGFBP-5 expression in 80.6% of cases. IGFBP-2 expression was totally absent in medulloblastoma. The extent of IGFBP-3 expression was higher in anaplastic when compared to classical and desmoplastic subtypes (p < 0.05). IGFBP-5 expression was significantly higher in classical and anaplastic subtypes when compared to desmoplastic medulloblastoma (p < 0.05). No influence of IGFBPs on survival was noted.

Conclusions: This is the first study to report expression of 3 cancer-related biomarkers - IGFBP-2, -3, -5 in medulloblastoma. Significantly higher extents of expression of IGFBP-3 in large cell variant and IGFBP-5 in classical and anaplastic subtypes suggest a plausible role of these molecules in specific molecular pathways of medulloblastoma.