CUR - The Council on Undergraduate Research

The Role of Carbonic Anhydrase IX in Acute Myeloid Leukemia and Development of a Potential Therapeutic Target

Austyn Colter, Callista Maguire, and Dr. George Sandusky, Department of Pathology, Indiana University School of Medicine, 340 W 10th St, Indianapolis, IN 46202 Dr. Heiko Konig and Dr. Mircea Ivan, Department of Medicine, Division of Hematology/Oncology, Indiana University School of Medicine, 340 W 10th St, Indianapolis, IN 46202

Acute myeloid leukemia (AML) is a rapidly growing form of blood cancer that affects approx. 20,000 patients in the US per year. Despite achieving a remission in response to intensive chemotherapy, most patients relapse and eventually die from their disease. Evidence suggests that this poor outcome is due to the survival of drug resistant AML cells in O2-deprived niches in the bone marrow (BM). In this study, RNAseq and PCR were employed to identify a potential marker to track hypoxic survival of leukemic cells. Characterization of gene expression was assessed using RNAseq; and Quantitative PCR reactions were performed using PowerUp SYBR GreenPCR Master Mix (Applied Biosystems, USA) on 7900HT Real-Time PCR System. Xenograft models of human AML were treated with varying doses of Cytarabine. In addition, BM from AML patients with drug-resistant disease were assessed for morphologic changes following chemotherapy. Human and mouse tissues underwent staining for Carbonic Anhydrase (CA)-IX and -XII via immunohistochemistry (IHC). Immunostaining was done by the Dako-Flex system platform. The Aperio Whole slide digital imaging system was used to create a digital image, and then computer-assisted morphometric analysis (positive pixel algorithm) was used to analyze the digital images. Our genomic studies demonstrated that CA-IX is the leading CA isoform expressed in AML cells under hypoxic stress conditions. These findings were in line with the results from our xenograft studies, where CA-IX staining was enhanced in leukemic cells remaining after chemotherapy. In patient cases, the blast count directly correlated with CA IX expression. We conclude that (i) due to its membrane-bound location, CA-IX represents a suitable therapeutic target and that (ii) inhibition of CA-IX might represent a useful approach to target drug resistant AML cells that reside in hypoxic environments, such as the BM niche.

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