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Personal History
I received my PhD in Biochemistry from Jadavpur University, India, and completed postdoctoral training at Max Planck Institute for Experimental Medicine (Germany), Roswell Park Cancer Institute (Buffalo, NY), and University of Maryland Biotechnology Institute (Baltimore, MD). I had been an Assistant Professor at the UMBI before joining the University of Maryland School of Medicine. I am a participating investigator at the University of Maryland Marlene and Stewart Greenebaum Cancer Center (UMGCC) and the Consortium of Functional Glycomics of the NIH. My research has been funded by the DOD and the NIH. I hold one US patent on early diagnosis of prostate cancer.
Research Interests
Structure, function, and regulation of galectins
My research interest has been in the area of basic and translational research of the carbohydrate-binding proteins (called lectins). Particularly, I am interested in structure, function and regulation of galectins (a family of beta-galactoside-binding lectins) and their interactions with the carbohydrates that mediate cell-cell and cell-extracellular matrix (ECM) interactions during normal and cancer development such as prostate and breast cancers. The prostate cancer cells differentially express several members of galectins, which alter normal cell-cell and cell-ECM interactions during cancer development. We have discovered a novel isoform of galectin-8 that may be relevant to prostate cancer cell proliferation. We have demonstrated cytosine methylation in galectin promoter in cancerous prostate, which may account for the differential expression of galectins during cancer development. Differential expression of galectin repertoire and identification of cytosine methylation of galectin gene promoters in normal and tumor prostate tissues have enabled us to develop a methylation-specific PCR based sensitive assay for early diagnosis of prostate cancer in biological fluids such as serum and urine. In another project, natural carbohydrate inhibitors of galectin are being employed to prevent breast cancer metastasis.
Lectin-nanoparticle conjugates to target cancer cells
Nanoparticles provide a new mode of cancer drug delivery as they function as a carrier for entry through fenestrations in tumor vasculature allowing direct cell access. Although this results in delivery of high drug concentrations to the targeted cancer cell, a considerable amount of normal cells are damaged and thus new technology is needed to reduce injury of normal cells. Several lectin-nanoparticle conjugates are being analyzed not only for delivering drugs specifically to cancer cells, but also for detection of cancer cells when imaging technologies are combined.
Zebrafish as a model organism for studying human cancer
The zebrafish is emerging as a powerful cancer model system as zebrafish neoplasms are in many cases similar to human cancers. The main advantages of zebrafish as a model organism are short generation times and transparent embryos that develop externally. Moreover, they are cheap and don't need much space, and can be genetically manipulated, both via reverse and forward genetics. In addition to these techniques, small molecule screens and genetic modifier screens are relatively easy to perform in zebrafish. Particularly, I am interested in developing methylation microarray specifically focused on CpG islands of zebrafish promoters. For this purpose, zebrafish are chemically induced to develop a specific cancer and then methylation pattern of genes are analyzed to gain insight into mammalian DNA methylation and the assembly of the genetic networks that regulate normal development and oncogenesis.
Postdoctoral Position Available:
A postdoctoral position is available to study protein-carbohydrate interactions and their epigenetic regulations in normal and cancer cells. Applicants should have a Ph.D. in molecular and cellular biology, biochemistry, or immunology with experience in standard molecular biology and protein techniques. A background in cancer biology and/or glycobiology is strongly encouraged. Preference will be given to applicants with experience in epigenetics, quantitative real-time PCR, flow cytometry, or confocal microscopy. For details of our research projects, send e-mail to hahmed@som.umaryland.edu.
Publications
Selected From 62 Peer-Reviewed Publications
Ahmed, H. (2010) Promoter methylation in prostate cancer and its application for the early detection of prostate cancer using serum and urine samples. Biomarkers in Cancer, 2, 17-33.
Craig, S.E., Thummel, R., Ahmed, H., Vasta, G.R., Hyde, D., and Hitchcock, P.F. (2010) The zebrafish galectin Drgal1-L2 is expressed by proliferating Muller glia and photoreceptor progenitors and regulates the regeneration of rod photoreceptors. Invest. Ophthalmol. Vis. Sci. 51, 3244-3252.
Poisa-Beiro, L., Dios, S., Ahmed, H., Vasta, G.R., Martínez-López, A., Estepa, A., Alonso-Gutiérrez, J., Figueras, A., and Novoa, B. (2009) Nodavirus infection of sea bass (Dicentrarchus labrax) induces up-regulation of galectin-1 expression with potential anti-inflammatory activity. J. Immunol. 183, 6600-6611.
Ahmed, H.*, Cappello, F., Rodolico, V., and Vasta, G.R. (2009) Evidence of heavy methylation in the galectin-3 promoter in early stages of prostate adenocarcinoma: Development and validation of a methylated marker for early diagnosis of prostate cancer. Translational Oncol. 2, 146-156.
Ahmed, H., Du, S.J., and Vasta, G.R. (2009) Knockdown of a galectin-1-like protein in zebrafish (Danio rerio) causes defects in skeletal muscle development. Glycoconjugate J. 26, 277-283.
Ahmed, H. and Vasta, G.R. (2008) Unlike mammalian GRIFIN, the zebrafish homologue (DrGRIFIN) represents a functional carbohydrate-binding galectin. Biochem. Biophys. Res. Commun. 371, 350-355.
Ahmed, H.*, Banerjee, P.B., and Vasta, G.R. (2007) Differential expression of galectins in normal, benign and malignant prostate epithelial cells: Silencing of galectin-3 expression in prostate cancer by its promoter methylation. Biochem. Biophys. Res. Commun. 358, 241-246.
Mercer, N., Ahmed, H., Etcheverry, S., Vasta, G.R., and Cortizo, A.M. (2007) Regulation of advanced glycation end product (AGE) receptors and apoptosis by AGEs in osteoblast-like cells. Mol. Cell. Biochem. 306, 87-94.
Ahmed, H., Du, S.J., O’Leary, N., and Vasta, G.R. (2004) Biochemical and molecular characterization of galectins from zebrafish (Danio rerio): notochord-specific expression of a prototype galectin during early embryogenesis. Glycobiology 14, 219-232.
Mercer, N., Ahmed, H., McCarthy, A.D., Etcheverry, S.B., Vasta, G.R., and Cortizo, A.M. (2004) AGE-R3/Galectin-3 expression in osteoblast-like cells: regulation by AGEs. Mol. Cell. Biochem. 266, 17-24.
Ahmed, H., Schott, E.J., Gauthier, J.D., and Vasta, G.R. (2003) Superoxide dismutases from the oyster parasite Perkinsus marinus: Purification, biochemical characterization, and development of a plate microassay for activity. Anal. Biochem. 318, 132-141.
Ahmed, H., Bianchet, M.A., Amzel, L.M., Hirabayashi, J., Kasai, K., Giga-Hama, Y., Tohda, H., and Vasta, G.R. (2002) Novel carbohydrate specificity of the 16 kDa galectin from Caenorhabditis elegans: Binding to blood group precursor oligosaccharides (type 1, type 2, T¿ , and Tß) and gangliosides. Glycobiology 12, 451-461.
Bianchet, M.A., Ahmed, H., Vasta, G.R., and Amzel, L.M. (2000) A soluble ß-galactosyl-binding lectin (galectin) from toad (Bufo arenarum Hensel) ovary: Crystallographic studies of two protein-sugar complexes. Proteins 40, 378-88.
Schwarz, F.P., Ahmed, H., Bianchet, M.A., Amzel, L.M., and Vasta, G.R. (1998) Thermodynamics of bovine spleen galectin-1 binding to disaccharides: correlation with structure and its effects on oligomerization at the denaturation temperature. Biochemistry 37, 5867-5877.
Ahmed, H., Pohl, J., Fink, N.E., Strobel, F., and Vasta, G.R. (1996) The primary structure and carbohydrate specificity of a ß-galactosyl-binding lectin from toad (Bufo arenarum Hensel) ovary reveal closer similarities to the mammalian galectin-1 than to the galectin from the clawed frog Xenopus laevis. J. Biol. Chem. 271, 33083-33094.
Ahmed, H. and Vasta, G.R. (1994) Galectins: conservation of functionally and structurally relevant amino acid residues defines two types of carbohydrate recognition domains. Glycobiology 4, 545-549.
Liao, D.I., Kapadia, G., Ahmed, H., Vasta, G.R. and Herzberg, O. (1994) Structure of S-lectin, a developmentally regulated vertebrate ß-galactoside binding protein. Proc. Natl. Acad. Sci. (USA) 91, 1428-1432.
Books and Book Chapters (Selected)
Ahmed, H. Silencing of galectin-3 by promoter methylation during prostate cancer progression: a novel transcriptional regulation of galectin-3 expression. In: Gene Silencing: Theory, Techniques and Applications, (Ed., F. Columbus), Nova Science Publishers, Hauppauge, NY (In press).
Vasta, G.R. and Ahmed, H. (Eds.) Animal lectins: a functional view, Taylor and Francis, Boca Raton, FL, 592 pages, 2008.
Ahmed, H., Rabinovich, G., Jackson, S. and Vasta, G.R. Animal models for assessing biological roles of animal lectins. In: Animal lectins: a functional view, (Eds. G.R. Vasta and H. Ahmed), Taylor and Francis (CRC Press), Boca Raton, FL, 85-114, 2008.
Bianchet, M.A., Ahmed, H., Vasta, G.R., and Amzel, L.M. Structural aspects of lectin-ligand interactions. In: Animal lectins: a functional view, (Eds. G.R. Vasta and H. Ahmed), Taylor and Francis, Boca Raton, FL, 13-31, 2008.
Ahmed, H. Principles and reactions of protein extraction, purification, and characterization, CRC Press, Boca Raton, FL, 408 pages, 2004. (2nd edition is under preparation).