Kristi Neufeld - US grants

tumor suppressor proteins; protein structure function; cell nucleus;

DESCRIPTION (provided by applicant): Colorectal cancer is the second deadliest malignancy in the United States. Mutation of the adenomatous polyposis coil (Apc) tumor suppressor gene initiates most colorectal carcinomas. However, it is not known how Apc mutation predisposes a cell to polyp development and colorectal carcinogenesis. Although APC is found at cell-cell junctions, binding to microtubules, and in the nuclei, little is known about nuclear APC function. We discovered increased cytoplasmic APC as human colon tissue progressed from normal, to polyp, to tumor. In cultured cells, APC localization responded to cell proliferation and phosphorylation. Furthermore, using this model we found that nuclear APC regulated the activity of the oncoprotein beta-catenin. We hypothesize changes in APC localization, initiated by mutation of the APC nuclear localization signals, will result in concomitant alterations in beta-catenin regulation, proliferation and differentiation at the cellular level, and polyp formation at the tissue level. We will inactivate APC's nuclear localization signals in mouse embryo-derived stem (ES) cells and whole animals to study nuclear APC function under physiological conditions. We will use these two innovative model systems to test directly if nuclear APC is involved in beta-catenin regulation (Aim 1), cellular proliferation (Aim 2), and differentiation (Aim 3). We will perform pathologic examinations on mice lacking nuclear APC to test if nuclear APC functions in tumor suppression (Aim 4). Greater knowledge of APC function in normal cells will improve our understanding of APC's role in tumorigenesis and ultimately illuminate new points for therapeutic intervention.

antigen presenting cell

DESCRIPTION (provided by applicant): Musashi-1 (Msi1) is a stem cell marker overexpressed in many types of cancers. Msi1 is an RNA-binding protein (RBP) that binds to and inhibits translation of target mRNAs. This inhibition results in activation of Wnt and Notch signaling and consequently, cell cycle progression, survival, and resistance to programmed cell death. Experimental manipulation to reduce Msi1 levels in breast and colon cancer cell lines leads to tumor regression in mouse xenograft models. Because Msi1 stimulates both Notch and Wnt signaling and is overexpressed in a wide variety of cancers, Msi1 is an attractive target for developing novel cancer therapy. So far there are no reported small molecule inhibitors of the Msi1-RNA interaction. RBPs such as Msi1 are considered undruggable due to the lack of a well-defined binding pocket for target RNA. Through high throughput screening, we have obtained initial hits at nanomolar Ki, which are validated by Surface Plasmon Resonance (SPR) and Nuclear Magnetic Resonance (NMR). Our hypothesize that small molecule compounds that disrupt Msi1-RNA binding will block Msi1 function, leading to translation of target genes that are critical for inhibiting cancer cell growth and progression. Our objective is to obtain a series of small molecule compounds as chemical probes that potently bind to Msi1 and modulate its function, and ultimately select 1-2 most drug- like lead compounds for further development as a whole new class of molecular cancer therapy that inhibit cancer with Msi1 overexpression. To test our hypothesis, three Specific Aims will be carried out: AIM 1, Structure-based rational design and lead optimization of Msi1-inhibitors; AIM 2, In vitro anti-tumor activity, target validation, and mechanism of action studies; AIM 3, In vivo efficacy studies of the lead Msi1-inhibitors in xenograft models of human cancer. Overall Impact: Successfully carried out, this project will discover novel chemical probes for Msi1 and potentially lead compounds as Msi1-inhibitors that inhibit cancer cells with high levels of Msi1-Notch/Wnt signaling. Discovery of such Msi1-inhibitors will: (1) provide potent and useful chemical probes for delineating the functional roles of Msi1-Notch/Wnt signaling in cancer initiation and progression; and (2) provide promising lead compounds to develop novel molecular therapeutics targeting the oncoprotein Msi1. The data and leads obtained will enable us to seek out partners for further drug discovery and development studies. After assessing structure-activity relationships and lead optimization, we may obtain a few lead compounds for further development as a whole new class of molecular cancer therapeutics that inhibit specific protein/RNA interactions required for cancer cell survival and progression.

Understanding how a single-celled zygote (the fertilized egg) develops into a multicellular animal with diverse, interconnected and properly-specified tissues is core to our understanding of how animals, including humans, actually work. One of the great discovery tools in developmental biology is the small nematode, Caenorhabditis elegans. Taking advantage of the available genetic tools in this organism, the large international community of C. elegans biologists, has made great strides in explaining the cellular and developmental mechanisms that govern how all animals function. For instance, it is now known that the same cell communication pathways control the development of diverse species, including C. elegans, and mammals like mice and humans. This collaborative project investigates the role of one of these conserved pathways in C. elegans development, focusing on asymmetric stem cell divisions. It will extend these studies to the most well-established mammalian example of a stem cell population, intestinal stem cells. In this way, it will determine the extent to which existing models of control of C. elegans stem cell divisions are conserved in mammals. Thus the research will provide a strong framework to address common problems that stem cells in these distantly-related animals encounter. The project will broaden the impact of these studies by 1) increasing public engagement and science literacy through hands-on workshops geared toward the general public, 2) recruiting the next generation of STEM scientists by bringing 8th graders from rural Iowa communities with large Hispanic populations to campus for a day of career simulations and 3) retaining current STEM undergraduates by extending undergraduate research opportunities, including to disadvantaged and underrepresented groups.


Asymmetric cell division (ACD) drives cell fate specification in animals from mammals to nematodes. Stem cells in these organisms use ACD to generate a differentiated daughter and a new stem cell. Wnt signaling is a conserved regulator of ACD and cell fate through its control of the transcriptional activator beta-catenin. The goal of this project is to elucidate the mechanisms of beta-catenin regulation during asymmetric stem cell divisions by analyzing regulation of the C. elegans beta-catenin, SYS-1, and to begin testing the resulting mechanisms in mammals. C. elegans is well-suited for these analyses because of its genetic and molecular tools, in vivo ACD imaging, the separation of the signaling and adhesion functions of beta-catenin into distinct genes and because of recent findings that SYS-1 is negatively regulated by homologs of the beta-catenin destruction complex: Axin, APC and CK1alpha. The mammalian intestinal crypt, arguably the best-known example of Wnt-controlled stem cell maintenance, will be used to test conservation of SYS 1 regulatory mechanisms and will also inform the worm models. This project will determine the mechanism by which Axin localizes the destruction complex, and the extent to which destruction complex regulation of beta-catenin in the nucleus is conserved. The results of these studies are predicted to provide broadly important insight into developmental cell fate specification and the role of Wnt pathway-induced ACD in tissue homeostasis.

Cancer Biology ? Project Summary The scientific goal of the Cancer Biology research program (CB) is to understand the molecular mechanisms that define normal and neoplastic cell growth in order to identify and characterize molecules, pathways and processes that are involved in tumor development, growth and progression that can serve as useful biomarkers and/or as new cellular targets for cancer therapeutics and prevention. CB represents the basic science initiatives of The University of Kansas Cancer Center (KUCC) and is unified by member utilization of molecular, biochemical and cell-based approaches to understand normal and cancer cell behavior. The Specific Aims of CB are: 1) to promote collaboration that enhances discovery of the mechanisms underlying tumor development, progression and malignant behavior; and 2) to leverage basic science discoveries to inspire pre-clinical and clinical development of novel cancer therapies. CB has 49 full members and 12 associate members from 17 departments located at KUMC, KU-Lawrence and Stowers. In 2015, CB garnered nearly $17M in cancer-related, peer-reviewed funding ($2M from NCI, $12.2M other NIH). CB members have published 617 articles since 2012 of which 144 (23%) had intra-programmatic, 128 (21%) had inter-programmatic and 315 (51%) had inter-institutional collaborations. These publications have been cited over 5,600 times, have an average journal impact factor (JIF) of 7.3 and 167 (27%) have a JIF?8. CB is jointly led by Kristi Neufeld (KU-Lawrence) and Linheng Li (Stowers), who bring complementary scientific expertise in cell biology, stem cell biology, biochemistry and translational research, leadership experience and diverse institutional representation. Danny Welch, Associate Director for Basic Science & Education and Jim Calvet, KUCC Research Staff Investigator, round out the leadership team and represent KUMC. Intra- and inter-programmatic collaborations are fostered by research retreats, seminars, research symposia and targeted pilot funding. CB has taken advantage of historical strengths in the study of three tumor sites over-represented in either incidence or mortality rate in the KUCC catchment area population (GI, kidney and hematopoietic). But rather than a disease-based thematic organization, CB members have expertise that can be organized into four discipline-based themes: 1) Cancer Cell Biology and Stem Cell Biology; 2) Cell Proliferation, Differentiation and Death; 3) Chromatin Organization and Transcriptional Regulation; and 4) Signaling Pathways and Development.