Department of Biochemistry N241 Beadle Center University Of Nebraska Lincoln, Nebraska 68588-0664 Phone (office):402-472-9309 (lab): 402-472-6808 FAX: 402-472-7842
Melanie Simpson	E-mail: msimpson2@unl.edu
Assistant Professor	B.S. 1992 - Biochemistry, University of Minnesota. Ph.D. 1997 - Biochemistry, Molecular Biology, and Biophysics, University of Minnesota.

Project Overview

In prostate cancer progression, prostate epithelial cells undergo phenotypic and genotypic changes that facilitate inappropriate proliferation, invasion of surrounding stromal matrices, entry into the lymphatic system and/or the bloodstream, and colonization of other tissues.  Hyaluronan (HA), a secreted glycosaminoglycan component of extracellular matrices, is critical for cellular proliferation and motility during development.  However, elevated circulating and cell associated levels correlate with various types of cancer, including prostate.  In histopathologic analyses of human prostate cancer, excessive stromal HA accumulation is detectable in early stages and intensifies throughout progression.  Eventually, advanced cancers exhibit tumor cell associated HA, which correlates to poor patient prognosis.

Aggressive prostate tumor cell lines were shown to synthesize excessive HA relative to less aggressive cells, and to express correspondingly higher levels of HA biosynthetic enzymes HAS2 and HAS3.  Inhibition of these enzymes by antisense HAS2 or HAS3 expression diminished HA synthesis and surface retention, and effected slower growth rate of cells in culture.  Subcutaneous injection of SCID mice with HAS antisense transfected cells produced tumors 3-4 fold smaller than control transfectants.  Tumors from HAS antisense transfectants were histologically HA deficient relative to controls.  Quantification of blood vessel density within tumor sections revealed 70-80% diminished vascularity of HAS antisense tumors.  Collectively, the results suggest HA synthase overexpression by prostate tumor cells may facilitate their growth and proliferation in a complex environment by enhancing intrinsic cell growth rates and promoting angiogenesis.

Current research in my lab is focused on understanding the causes and impacts of HA overproduction by prostate tumor cells. Specifically, we are interested in identifying external regulatory mechanisms leading to HAS overexpression, as well as defining the processes by which tumor cells accumulate and retain surface HA. We are also characterizing changes in intracellular signaling that result from altered HA synthesis and the effect of these changes on prostate tumor cell behavior in mouse orthotopic injections.

 

Simpson MA and Lokeshwar VB. Hyaluronan and hyaluronidase in genitourinary cancers.
Invited Review. Frontiers in Bioscience. In press.

Bharadwaj AG, Rector K, Simpson MA. (2007) Inducible hyaluronan production reveals
differential effects on prostate tumor cell growth and tumor angiogenesis. J Biol Chem. 282(28):
20561-72.

Kovar JL, Simpson MA, Geschwender A and Olive DM. (2007) A systematic approach to the
development of fluorescent contrast agents for optical imaging of mouse cancer models. Review.
Anal Biochem. 367(1): 1-12.

Kovar JL, Volcheck WM, Chen J and Simpson MA. (2007) Purification method directly influences
effectiveness of an epidermal growth factor-coupled targeting agent for noninvasive tumor
detection in mice. Anal Biochem. 361(1): 47-54.

Easley KE, Sommer BJ, Boanca G, Barycki JJ, and Simpson MA. (2007) Characterization of
human UDP-glucose dehydrogenase reveals critical catalytic roles for lysine 220 and aspartate
280. Biochemistry 46(2): 369-78.

Kovar JL, Johnson MA, Volcheck WM, Chen J and Simpson MA. (2006) Hyaluronidase induces
prostate tumor metastasis in an orthotopic mouse model. Amer J Pathol. 169(4): 1415-26.
Simpson MA. (2006) Concurrent expression of hyaluronan biosynthesis and processing
enzymes promotes growth and vascularization of prostate tumors in mice. Amer J Pathol. 169(1):
247-57.

McCarthy J, Turley E, Wilson C, Price M, Bullard K, Beck M, Simpson M. (2005) Hyaluronan
biosynthesis in prostate carcinoma growth and metastasis. In Hyaluronan: Structure, Metabolism,
Biological activities, Therapeutic Applications; Chapter 4, Hyaluronan and Tumors. Eds E.A.
Balasz and V.C. Hascall.

Sommer BJ, Barycki JJ, and Simpson MA. (2004) Characterization of human UDP-glucose
dehydrogenase: Cys 276 is required for the second of two successive oxidations. J Biol Chem.
279: 23590-96.

Yang J, Price MA, Wilson C, Ferrone S, Neudauer CL, Xia H, Iida J, Simpson MA, McCarthy JB.
(2004) Melanoma chondroitin sulfate proteoglycan enhances focal adhesion kinase and ERK
activation by distinct mechanisms. J Cell Biol. 165: 881-91.

Kim HR, Wheeler MA, Wilson CM, Iida J, Eng D, Simpson MA, McCarthy JB and Bullard KM.
(2004) Hyaluronan Facilitates Invasion of Colon Carcinoma Cells In Vitro via Interaction with
CD44. Cancer Res. 64: 4569-76.

McCarthy JB and Simpson MA. (2003) Hyaluronan in prostate cancer progression. Glycoforum
online reviews (invited). http://www.glycoforum.gr.jp/science/hyaluronan/HA26/HA26E.html

Bullard KM, Kim HR, Wheeler MA, Wilson CM, Neudauer CL, Simpson MA, McCarthy JB. (2003)
Hyaluronan synthase-3 is upregulated in metastatic colon carcinoma cells and manipulation of
expression alters matrix retention and cellular growth. Int J Cancer 107(5): 739-46.