Low expression of p27 indicates a poor prognosis in patients with high-grade astrocytomas.

Background: Two families of tumor suppressor genes, Cip/Kip (p21, p27, and 57) and INK4 (p15, p16, p18, and p19), regulate cell proliferation and neoplastic transformation. p27 exerts its suppressor effect through cyclin E-dependent kinase (CDK2) by inhibiting the phosphorylation of pRb by CDK2, which, in turn, arrests cells in the G1-phase. p21 has a similar effect in addition to participating in the p53 dependent CDK4-mediated and CDK6-mediated pathway.

Prognostic value of the expression of tumor suppressor genes p53, p21, p16 and prb, and Ki-67 labelling in high grade astrocytomas treated with radiotherapy.

Cumulative inactivation of tumor suppressor genes and/or amplification of oncogenes lead to progressively more malignant astrocytic tumors. We have analyzed the significance of tumor suppressor genes p53, p21, p16 and retinoblastoma protein (pRb) and proliferative activity for survival in 77 high grade astrocytic tumors. After operation, the patients--25 anaplastic astrocytomas (AA) and 52 glioblastomas (GBs)--were treated with similar radiotherapy.