Variant of the CHEK2 gene as a prognostic marker in glioblastoma multiforme.

OBJECTIVE: Germline mutations of the CHEK2 tumor suppressor gene have been found in families with the Li-Fraumeni syndrome (LFS). Patients with LFS experience a variety of cancers, including malignant astrocytomas. We investigated a potential role for a CHEK2 gene polymorphism in glioblastomas. METHODS: A genetic polymorphism of the CHEK2 gene (CHEK2 SNP rs2017309 A/T) was genotyped in a series of glioblastoma patients (n = 213) and population controls (n = 192). Subsets of tumors were analyzed for loss of heterozygosity 22q(n = 66), loss of heterozygosity CHEK2 (n = 53), CHEK2 expression (n = 21), and CHEK2 coding sequence alterations (n = 18). CHEK2 SNP rs2017309 genotyping findings and traditional clinicopathological parameters were correlated with the patients' prognoses. RESULTS: No association between the CHEK2 SNP and glioblastoma formation was observed. No CHEK2 coding sequence aberrations or tumors completely lacking CHEK2 protein were identified. However, the presence of the CHEK2 rs2017309 A allele was significantly associated with an adverse prognosis (P = 0.034), particularly among patients undergoing postoperative chemotherapy and radiotherapy (n = 28, median survival 10.5 versus 15.5 mo, P = 0.008). We could confirm the patients' age, Karnofsky Performance Scale score, and postoperative radiotherapy and chemotherapy (all P < 0.0001, log-rank test) as decisive prognostic factors. CONCLUSION: Our data suggest that a CHEK2 gene polymorphism might correlate with the prognosis of glioblastoma patients. These findings may point to an as yet unrecognized role for the CHEK2 gene in glioblastomas.

Role of p16 and p14ARF in radio- and chemosensitivity of malignant gliomas.

In addition to cytoreductive surgery, most patients with malignant gliomas also undergo radio- and chemotherapy. An improved understanding of the molecular genetic mechanisms underlying the radio- and chemosensitivity of gliomas may help to identify glioma patients who will benefit from aggressive and, therefore, potentially toxic adjuvant treatment. It may also allow for the development of new therapies aimed at improving the response of these tumors towards chemo- and radiotherapy. The INK4a gene products, p16 and p14ARF, have been suggested as potential regulators of glioma chemo- and radiosensitivity. We have used tetracycline controlled expression of p16 and plasmid-based p14ARF expression to study the chemo- and radiosensitivity of glioma cell lines. Ectopic p16 sensitized U-87MG cells towards treatment with vincristine and possibly also BCNU by approximately 1.5 to 2-fold, and towards ionizing radiation by a factor of 1.5. p14ARF expression was found to render U-87MG cells 2-fold more radioresistant than controls. These findings support a role for p16 and p14ARF as modulators of the radio-and chemosensitivity of gliomas. Further studies of the role of cell cycle regulators in glioma chemo- and radio-sensitivity seem warranted. We would like to point out that such candidate genes which may code for potent growth suppressors (like p16) or even toxic gene products can be successfully investigated using the approach detailed in this manuscript.