Abstract 3110: MASH1 expression in high grade astrocytoma may demonstrate a potential model for prognosis that may lead to a molecular target for future therapy

Abstract

Abstract Introduction: A large U.S. study showed that 25% of patients diagnosed with grade 3 astrocytoma survived for 5 years or more after diagnosis. Unfortunately, the outlook is even worse for patients diagnosed with GBM, as most patients live for less than a year. Achaete-scute complex homolog 1 (ASCL1, MASH1) is a proneural transcription factor that has an essential role in the formation of multiple neuronal lineages. Recent studies have shown that the upregulation of MASH1 and inhibition of the Notch signaling pathway characterize progressive astrocytoma. Proneural proteins have been shown to regulate stem-cell proliferation and differentiation. The convergence with oncogenic pathways combined with the overexpression in glioblastoma has been shown to correlate with poor clinical outcome and has identified these transcription factors as promising therapeutic targets. Recently, a MASH1 mouse monoclonal antibody has been developed. Most studies have shown MASH1 to be a specific marker of neuroendocrine carcinomas; however, only one immunohistochemical study on astrocytoma using a polyclonal antibody has been reported. This study examined MASH1 expression in grade 1-4 astrocytoma cases. Materials and Methods: Formalin-fixed paraffin-embedded tissue microarrays consisting of samples of normal brain and astrocytomas [grade 1 (n = 22), grade 2 (n = 34), grade 3 (n = 16) and glioblastoma (n = 35)] were evaluated by immunohistochemical analysis using a monoclonal MASH1 antibody. A value of >1% staining was scored as positive. Results: MASH1 stained 61.7% (66/107) of astrocytomas (grades 1-4). In grade 1 astrocytoma, MASH1 was expressed in 31.8% versus 85.3% in grade 2, 68.7% in grade 3 and 54.3% in grade 4 (p ∼ 0.0028). Conclusion: MASH1 is highly expressed in astrocytoma. There was a variable and progressive increase of MASH1 expression in grade 1 versus grade 2-4 astrocytoma; and thus, may demonstrate a potential model for prognosis that may lead to future target therapeutic strategies. Citation Format: David E. Tacha, Jillian Tyrrell, Margaret Lobo. MASH1 expression in high grade astrocytoma may demonstrate a potential model for prognosis that may lead to a molecular target for future therapy. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3110.