Abstract 1573: MLPA and REMBRANDT data predict potential modulation of vitamin D via increased CYP27B1 in aggressive primary brain tumors
Authors: Beckner Marie E. , Patil Shashikant , LeBlanc Jay F. , Katira Kristopher , Nanda Anil , Martin Sherry S. , Brunson Lee Ellen , Truong Long N. , Nordberg Mary L. 
Published: February 2011

Glioblastomas are lethal, aggressive primary brain tumors that resist therapies. We hypothesized that their analysis using multiplex ligation probe amplification (MLPA) kits (MRC Holland, The Netherlands) with probes for 81 genes could aid in selection of individualized treatments for patients. Genes tested in P171, P172, P173 MLPA kits are known to have increased copy numbers in various tumors. DNA was purified from 4 glioblastomas, 1 meningioma, & 1 metastatic carcinoma (lung primary). No gene amplifications were shown in the meningioma or brain metastasis. Probes detected gene amplifications in the glioblastomas: all 4 had amplified EGFR and two (50%) had additional amplifications of CDK4 and CYP27B1. One of these also had amplification of PDGFRA and MDM2. Amplification of CYP27B1 at 12q13.3 was related to CDK4 at 12q14 as shown by simultaneous occurrence in 2 of the 4 glioblastomas. Products of the amplified genes are related to cell proliferation with CYP27B1's effects indirectly mediated through its metabolism of vitamin D (not shown here). Gene amplifications in tumor samples were quantified by calculating the fold increase versus the same gene in commercial normal brain DNA tested concurrently. At least 6 other genes (no apparent changes between normal and tumor) in each MLPA kit were used for normalization between the two samples in each case. Genes amplified in at least 2 tumors, included EGFR, 6.8 − 31.5 fold, CDK4, 6.7 − 17.8 fold and CYP27B1, 3.3 − 9.7 fold increased. All were reported previously as being amplified in some glioblastomas, with a lower percent noted for CYP27B1 than here. Although survival data for copy numbers of these genes in the NIH's REMBRANDT database are limited to EGFR, survival data for their gene expressions (median reporters) are available for 297 gliomas with poorer survival indicated for increased EGFR (3-fold, p = 0.0017), CYP27B1 (2-fold, p = 0.0284) and MDM2 (2-fold, p = 0.0397) in 112, 102, and 100 patients, respectively, but not for increased expression of CDK4 or PDGFRA. Each group with poorer survival contained approximately 80% high grade gliomas, grades III-IV/IV. Chi-square analysis of REMBRANDT data confirmed the relationship between CYP27B1 and CDK4 with p = 9.04 × 10−5 for co-expression of both when increased 2-fold and p = 3.97 × 10−13 for 2-fold increased CYP27B1 with 3-fold increased CDK4. Analysis of CYP27B1 should be included in genomic surveys of brain tumors performed for designing individualized treatments in that vitamin D levels are potentially modulated due to amplification of the gene encoding one of its metabolic enzymes. We acknowledge Louisiana State University Health Sciences Center - Shreveport's Fall 2008 Grant-In-Aid funding, Dwain D'Souza, LSUHSC-S, for technical support and use of the Repository of Molecular Brain Neoplasia Database (REMBRANDT) at NCI & NINDS at NIH, http://rembrandt.nci.nih.gov.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1573.