Application of advances in molecular biology to the treatment of brain tumors
ABSTRACT Recent advances in molecular biology have substantially improved our understanding of the molecular genetics of primary brain
neoplasms. Soon each histopathologic category of glioma will be further divided into subgroups according to similar genetic
background, gene expression profile, and similarity of biologic responses to radiotherapy or chemotherapy. Identification
of key molecules that are specifically altered in neoplastic cells will provide candidate molecular targets for tumor treatment.
Novel therapeutic tools for targeting tumor cells, such as viral vectors for gene therapy, have been created. In the near
future, the accumulation of new knowledge in brain tumor biology and genetics, combined with rational drug design, will revolutionize
the treatment of malignant gliomas, which are among the most lethal human cancers.
- The Lancet 02/1997; 349(9044):2-3. · 39.06 Impact Factor
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ABSTRACT: Cyclin-dependent kinase 4 inhibitor (CDKN2/p16) is a cell cycle regulatory protein that has been demonstrated to be inactivated by mutations, deletions or transcriptional silencing during pathogenesis of a variety of human malignancies. We studied the correlation of CDKN2/p16 expression with cell proliferation activity and patient survival in 42 oligodendrogliomas and 36 astrocytomas. CDKN2/p16 expression was frequently decreased in grade II and anaplastic oligodendrogliomas (17/42) where lack of CDKN2/p16 protein predicted poor survival (p=0.0045). In astrocytomas low CDKN2/p16 expression was associated with high histologic malignancy grade (p=0.002): CDKN2/p16 protein level was decreased in 9 out of 10 glioblastomas, in 5 out of 9 anaplastic astrocytomas, in 3 out of 10 grade II astrocytomas and in none of pilocytic astocytomas (0/7). Low CDKN2/p16 expression was also associated with high cell proliferation activity (MIB-1 immunocytochemistry: p=0.004; mitotic index: p=0.007) and poor patient survival (p=0.025) in astrocytomas. Low CDKN2/p16 mRNA expression had the same topographic distribution as nuclear CDKN2/p16 immunoreactivity proving for reliability of the immunocytochemical findings. Our results are in agreement with earlier studies demonstrating CDKN2/p16 inactivation during tumorigenesis of astrocytic tumors. Furthermore, our findings suggest that loss of CDKN2/p16 expression may also play an important role in the progression of oligodendrogliomas. According to our findings CDKN2/p16 immunocytochemistry could be used as a tool to identify those oligodendrogliomas and low grade astrocytomas that are likely to progress and have poor outcome, and thus would need more aggressive therapy.Journal of Neuro-Oncology 01/1999; 41(3):205-211. · 3.12 Impact Factor
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ABSTRACT: BACKGROUND/METHODS: Gliomas are common malignant neoplasms of the central nervous system. Among the major subtypes of gliomas, oligodendrogliomas are distinguished by their remarkable sensitivity to chemotherapy, with approximately two thirds of anaplastic (malignant) oligodendrogliomas responding dramatically to combination treatment with procarbazine, lomustine, and vincristine (termed PCV). Unfortunately, no clinical or pathologic feature of these tumors allows accurate prediction of their response to chemotherapy. Anaplastic oligodendrogliomas also are distinguished by a unique constellation of molecular genetic alterations, including coincident loss of chromosomal arms 1p and 19q in 50%-70% of tumors. We have hypothesized that these or other specific genetic changes might predict the response to chemotherapy and prognosis in patients with anaplastic oligodendrogliomas. Therefore, we have analyzed molecular genetic alterations involving chromosomes 1p, 10q, and 19q and the TP53 (on chromosome 17p) and CDKN2A (on chromosome 9p) genes, in addition to clinicopathologic features in 39 patients with anaplastic oligodendrogliomas for whom chemotherapeutic response and survival could be assessed. RESULTS/CONCLUSIONS: Allelic loss (or loss of heterozygosity) of chromosome 1p is a statistically significant predictor of chemosensitivity, and combined loss involving chromosomes 1p and 19q is statistically significantly associated with both chemosensitivity and longer recurrence-free survival after chemotherapy. Moreover, in both univariate and multivariate analyses, losses involving both chromosomes 1p and 19q were strongly associated with longer overall survival, whereas CDKN2A gene deletions and ring enhancement (i.e., contrast enhancement forming a rim around the tumor) on neuroimaging were associated with a significantly worse prognosis. The inverse relationship between CDKN2A gene deletions and losses of chromosomes 1p and 19q further implies that these differential clinical behaviors reflect two independent genetic subtypes of anaplastic oligodendroglioma. These results suggest that molecular genetic analysis may aid therapeutic decisions and predict outcome in patients with anaplastic oligodendrogliomas.JNCI Journal of the National Cancer Institute 11/1998; 90(19):1473-9. · 14.34 Impact Factor