Abstract 5618: Tumor suppressor genes? The status of genes PAX 5&6 in primary and secondary gliomas and glioblastoma multiforme tumors

Abstract

Abstract Background: Gliomas are the most common brain tumors, and glioblastoma multiforme (GBM) tumors have the poorest prognosis, and due to their molecular heterogeneity, these tumors remain incurable and highly resistant to treatments, in most cases. The PAX (paired box) family of genes is comprised of are nine members that are subdivided based on the products of their protein domain structures. PAX5 and PAX6 are developmental genes that are vital during embryonic stages of development, and their transcription factors have supportive, if not, key functions in tumorigenesis. Interestingly, gene PAX6 has been reported to be over and under expressed in high grade gliomas, GBMs, and glioma cell lines. However, these results could be an effect of upstream or downstream manipulation of other transcription factor(s), the origin of the tissue (PAX6 expression is restricted to the forebrain, optic cup, hindbrain, and spinal cord, lens placode, and nasal epithelium), and the epigenetic regulation of some other gene. In addition, there are no reported mutations in either gene PAX5 or PAX6 in the cells from GBMs. Therefore, confusion exists as to role these genes have in tumorigenesis, and whether either gene has the properties or characteristics of a tumor suppressor gene. Study Objective: The overall study objective was to determine if either PAX5 or PAX6 are tumor suppressor genes, and can be silenced or over-expressed to inhibit the progression of cultured human adult primary glioma tissue samples, by employing small interfering RNA (siRNA) methodology. Methods: Primary cell cultures were incubated in reduced serum conditions for at least 1 month prior to transfections and cells were passed every 7 to 10 days or when flask was 90% confluent. To investigate and measure true inhibition of cell proliferation or progression of the cells, several techniques were used, such as, real-time quantitative reverse transcription PCR, enzyme-linked immunosorbent assays, and immunohistochemistry. Results: The high grade (IV) primary glioma tissue samples and their respective cell cultures showed relatively high expression levels for the gene PAX6 and lower levels of expression for gene PAX5 when compared to GAPDH gene and standard controls. Our initial transfections for knocking down of PAX6 using siRNA (TriFECTA, IDT) showed 90% of control samples were transfected, and our primary cells were knockdown by 82%, 70%, and 65% for each of PAX6 isoforms (N000280.21.1-S, 2-S, and 3-S) respectively. We are currently analyzing the rest of the PAX6 data and all of the PAX5 data. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5618. doi:1538-7445.AM2012-5618