Laboratory Research Faculty
Roman Perez-Soler, M.D., Professor and Chairman
rperezso@montefiore.org
Our laboratory is interested in the development and understanding of new molecular therapies for lung cancer and other solid tumors. An area of preferential focus for us has been the development of novel drugs delivery systems and currently our basic strategy is to combine approaches that involve anatomical as well as molecular targeting.
We have extensively explored the use of liposome carriers to deliver novel, non cross resistant platinum, anthracyclines and more recently camptothecin agents. These efforts have in the past resulted in the introduction of two new agents in clinical trials. One major interest at this oint is the development of aerosolized therapies as an early intervention approach to repair tobacco-induced bronchial damage. We have shown proof of principle using gene corrective therapy with the p53 gene in a liposome carrier and we are currently exploring the use of demethylating agents, COX-2 inhibitors, and anti EGFR agents via inhalation. We expect to initiate a clinical study with aerosolized p53 in 2004. Another area of major interest is understanding the mechanisms of action and resistance of EGFR inhibitors. We have been at the forefront of showing that these agents have significant clinical activity in non-small cell lung cancer. We have developed cells lines resistant to some of these agents and are analyzing the mechanisms of acquired resistance. Another area of activity has been the cell cycle effects and mechanisms of apoptosis of a variety of chemotherapeutic agents, particularly M-Phase blockers like the taxanes, the proteasome inhibitor PS341 and arsenic trioxide.
Finally, we have great interest in the development of clinically relevant in vivo models of lung cancer. We have a longstanding experience with heterotransplants of human tumors and are actively involved in identifying the determinants of successful tumor take. We have recently discovered that the downregulation of H-cadherin secondary to promoter hypermethylation is an important factor for the successful growth of these tumors in nude mice. We are currently studying whether these tumors can be used to predict tumor response in patients and also developing in vivo resistant tumors to a variety of antitumor agents
Leonard Augenlicht, Ph.D., Professor and Associate Chair for Research
augen@aecom.yu.edu
Our interests focus on the initiation and modulation of tumorigenesis by genetic and dietary factors, and especially, there interactions. We have developed and utilize novel mouse genetic strains and cell culture systems, and direct experiments on patient tissues to dissect cellular and molecular pathways of intestinal cell maturation, how these are normally coordinated to maintain mucosal homeostasis, and the perturbations that arise during tumorigenesis. Major interdisciplinary programs funded by the NCI include: molecular analysis of how factors in the western diet that predispose to colon cancer interact with genetic pathways to establish risk and site specificity for tumor formation; and determination of the mechanisms that establish relative sensitivity to chemopreventive and chemotherapeutic agents for intestinal cancer.
Robert E. Gallagher, M.D., Professor
rgallagh@aecom.yu.edu
The main interest of my laboratory is in acute promyelocytic leukemia (APL), a subclass of acute myeloid leukemia that provides a model for studying the therapeutic mechanisms of action and resistance of a variety of bioeffectors. These include all-trans retinoic acid (ATRA), which eliminates APL cells by inducing terminal differentiation; arsenic trioxide (ATO), which induces apoptosis and terminal differentiation; and chromatin active agents, such as histone deacetylase and DNA methyltransferase inhibitors, which can augment the anti-leukemic effects of RA and ATO. Since APL is a relatively infrequent disease, molecular biological correlative studies are conducted in the context of large multi-institutional studies, including nationwide cooperative oncology group protocol studies. More basic mechanistic stuidies are conducted using APL cell culture resources. A current focus is on understanding a unique mechanism of APL cell ATRA resistance. Despite the fact that ATRA is the quintessential example of targeted gene therapy and although the development of clinical resistance is frequently associated with the acquisition of mutations in the ATRA target gene PML-RARa, disease relapse with PML-RARa mutations is often not related to therapeutic ATRA selection pressure. This clinically-related observation differs from other examples of leukemia relapse associated with gene-targeted drug resistance, and it suggests that a novel mechanism of APL subclonal selection is involved leading to relapse, which is likely related to alternative functions of mutant PML-RARa as an aberrant nuclear transcription factor.
Edward L. Schwartz, Ph.D., Professor
eschwart@aecom.yu.edu
The formation of new blood vessels (angiogenesis) is a critical process in the growth of tumors and provides a means by which they can spread to distant sites. My laboratory explores the mechanisms by which certain angiogenic factors stimulate blood vessel-forming endothelial cells, studies the molecular actions of experimental and established cancer chemotherapeutic drugs which inhibit the angiogenic process, and participates in the design and testing of new agents which could provide novel clinical approaches to inhibit angiogenesis in cancer. Among our current interests are the understanding of signal transduction pathways which mediate migration in the endothelial cell, including the formation of focal adhesions, the activation of cell surface integrins, the phosphorylation and activation of regulatory proteins, and the interaction of these components with microtubules and the cell cytoskeleton.
Cy A. Stein, M.D., Ph.D., Professor
cstein@montefiore.org
G3139 is a phosphorothioate oligonucleotide targeted to the initiation codon region of the bcl-2 mRNA. This molecule has recently, and successfully, completed a global, randomized phase III trial in combination with DTIC for advanced melanoma, and the data on other phase III trials is pending. However, although G3139 is purported to be active by an antisense mechanism of action, its behavior is actually quite complex. For example, in prostate cancer cells, G3139, as demonstrated by an oligonucleotide microarry analysis, induces the interferon cascade in the absence of induction of the production of interferon proteins. This apparently leads to cellular cytostasis (at least in prostate cancer cells), rather than apoptosis, but does not lead to chemosensitization, as might have been anticipated when the expression of the anti-apoptotic protein bcl-2 has been decreased. In fact, if prostate cancer cells are treated with interferons, many aspects of the G3139-induced phenotype can be recapitulated. These aspects include downregulation of bcl-2 protein and mRNA, and inhibition of cell growth. However, other aspects of the G3139-induced phenotype, including the generation of reactive oxygen species, are not recapitulated by interferon treatment. However, if bcl-2 protein expression is downregulated by a (purportedly) highly specific siRNA approach, no apparent phenotype (e.g., growth suppression, reactive oxygen species production) is produced either in prostate cancer cells, or in 518A2 melanoma cells. Additional research suggests that the production of the G3139 phenotype does not depend on the downregulation of bcl-2 expression, but rather on the presence of the subsequence motif CGNNCG contained within the molecule. The mechanism of action of this motif is now being intensively investigated, along with its apparent ability to induce the generation of reactive oxygen species. These studies have great relevance to the future development of DNA medicines, and to the use of bcl-2 as a therapeutic target.
Barbara G. Heerdt, Ph.D., Associate Professor
heerdt@aecom.yu.edu
Transformation of colonic epithelial cells is characterized by early defects in mitochondrial activity. The research in my laboratory focuses on mitochondria in risk, progression and prevention of colon cancer. Our recent work indicates that the intrinsic mitochondrial membrane potential plays a critical role in defining the probability of colonic tumorigenesis and progression.
Anna Velcich, Ph.D., Associate Professor
velcich@aecom.yu.edu
Our laboratory is interested in the molecular mechanisms that regulate intestinal cell differentiation and homeostasis and how these processes are deregulated in tumorigenesis. We approach these problems by the integration of in vivo and in vitro models using genetically engineered mice and cell lines that partially recapitulate in vivo events. Specifically, we investigate the regulation of the MUC2 gene, which encodes the major gastrointestinal mucin and the expression of which is restricted to mature, fully differentiated intestinal goblet cells in physiological conditions.
Projects ongoing in the lab include:
Role of MUC2 in intestinal carcinogenesis. MUC2 encodes the major form of secreted gastrointestinal mucins. Importantly, in many aberrant crypt foci, which are considered pre-malignant lesions in the flat mucosa of individuals genetically predisposed to develop colon cancer, there is an under representation of goblet cells, the cell lineage that expresses, synthesizes and secrete MUC2 mucin. To investigate whether MUC2 plays a role early in tumorigenesis, we have generated a Muc2 null mouse by homologous recombination. These mice spontaneously develop intestinal and rectal tumors. Experiments utilizing genetics (crosses with mice that carry genetic alterations shown to play a role in intestinal tumorigenesis), genomics (molecular profiling technology) and biochemical-molecular tools are under way to investigate the molecular mechanisms of tumor development in the Muc2-/- mice.
Mucus has an important role in regulating colonic cells/bacteria interactions. Mounting evidence points at the importance of microbial population in colorectal tumor development. Absence of Muc2 may not only expose underlying epithelial cells to bacteria, but also change the taxonomy of bacterial group favoring the colonization of strains that are associated with colon cancer. In future experiments we are planning to generate mice with gnotobiotic flora to ascertain the contribution of specific strains to the development of colon cancer in the Muc2-/- mice.
Regulatory studies of MUC2. Our work on the regulation of the MUC2 gene has identified a series of compounds defined by their ability to inhibit histone deacetylase (HDAC) activity, which repress MUC2 gene expression in in vitro cell systems. HDAC inhibitors are a new class of compounds that have recently been in clinical trials for a variety of cancers (such as Butyrates, Saha, and valproic acid). Most relevant for our studies is the action of sodium butyrate (NaB), a short chain fatty acid, which is a natural compound generated by the bacterial fermentation of fibers in the intestine. NaB is an inducer of differentiation of intestinal tumor cell in vitro, while in vivo promotes cell growth being the major energy source for colonocytes. We are currently investigating the mechanisms of NaB induced repression of MUC2 expression by modifying the levels of HDACs using expression vector and RNA interference approaches. Understanding the interaction between HDAC inhibitors and MUC2 gene expression can have an impact on managing mucinous tumors, which are characterized by large production of mucus, and MUC2 overexpression. In addition, it may contribute in reducing the metastatic potential of late stage cancers that has been linked to increased MUC2 expression.
Dineo Khabele, M.D., Assistant Professor
dkhabele@montefiore.org
The primary focus of this laboratory is the study of genetic alterations in ovarian cancer, utilizing cDNA microarrays, quantitative real time reverse transcriptase polymerase chain reaction (QPCR) and tissue microarrays. We are employing these techniques to dissect the molecular pathways related to tumor necrosis factor-related genes and histone deacetylase genes in order to provide further insight into mechanisms of ovarian cancer development and the use of novel therapies to treat ovarian cancer.
Lidija Klampfer, Ph.D., Assistant Professor
lklampf@aecom.yu.edu
Our laboratory is studying how activating Ki-ras mutations promote transformation of intestinal epithelial cells and regulate the responsiveness of cancer cells to chemopreventive and chemotherapeutic agents. We have available isogenic colon cancer cell lines that differ only by the presence of the mutant Ki-ras allele. A genome-wide survey of Ras target genes was performed on these cells and we identified several downstream effectors of Ras signaling that mediate its ability to regulate proliferation, apoptosis and differentiation. Among the downstream targets of Ras signaling were several genes that regulate apoptosis, including gelsolin, a putative tumor suppressor gene whose expression is frequently reduced in colon cancers. One of the projects in the laboratory is to define the role of gelsolin in apoptosis induced by chemopreventive and chemotherapeutic agents and to establish its role in the progression of colon cancer in vivo using a compound mouse model containing both APC1638 mutation and gelsolin null mutation.
In a second project, we are studying the impact of Ras signaling on the expression of Interferon target genes, some of which shape tumor immunogenicity, curb cellular proliferation, promote apoptosis and differentiation and inhibit angiogenesis. We demonstrated that the expression of STAT1, STAT2 and IRF-9, transcription factors that are required for signaling by interferons, is reduced in cells that harbor an activated Ras mutation. Our goal is to uncover the pathways activated by Ras that interfere with IFN signaling, and to determine the biological significance of the antagonism between Ras and IFN/STAT signaling.
John M. Mariadason, Ph.D., Assistant Professor
jmariada@aecom.yu.edu
Deregulation of cell proliferation, differentiation and apoptosis are fundamental to the development of colon cancer. The focus of my laboratory is to investigate the role of histone deacetylases (HDACs) in the regulation of these processes using in vitro model systems of colonic epithelial cell differentiation (Caco-2 cell line, butyrate treatment), and in the mouse intestine in vivo. We are also utilizing high density cDNA microarrays for the characterization of pathways of normal intestinal cell differentiation and tumorigenesis, and for the identification of profiles of gene expression predictive of response of colon tumors to chemotherapy.
