1998 — 2002 |
Spinella, Michael J |
K01Activity Code Description: For support of a scientist, committed to research, in need of both advanced research training and additional experience. |
Retinoid Induced Tumor Differentiation and the Cell Cycl
DESCRIPTION (Applicant's Description): The objective of this proposal is to identify mechanisms linking RA-induced tumor differentiation to changes in the cell cycle leading to G1-S arrest. Elucidating how initiation of tumor differentiation is coupled to the cell cycle machinery should lead to a greater fulfillment of the potential of maturation-based cancer therapy. The human germ cell cancer (teratocarcinoma) cell line, NT2/D1, arrests in G1 during RA-induced neuronal differentiation. Preliminary data indicate in response to RA, NT2/D1 cells show a progressive d e c l ine in cyclin D1 expression that parallels a decline in cell proliferation. Phenotypic maturation and accumulation of cells in G1 occur thereafter. An RA-resistant clone, NT2/D1-R1, shown not to express the retinoid receptor-gamma (RARgamma), did not accumulate in G1 and persistently overexpressed cyclin D1 and p53. Exogenous RARgamma expression reversed RA resistance and restored RA-mediated decline of cyclin D1. This proposal is designed to learn how RA signals those cell cycle changes causing growth suppression. The first specific aim identifies the mechanisms by which RA achieves G1 arrest by comparing the biochemical activity and expression of known mediators of G1-S progression in RA-sensitive and resistant NT2/D1 cells. The second specific aim determines whether RA-induced cell cycle changes are causal in mediating induced growth suppression and maturation by studying the RA sensitivity of cells engineered to overexpress cyclin D1, p53 and other highlighted cell cycle components. The third specific aim explores the role of RARs in signaling RA-induced changes in the cell cycle by individually over-expressing specific retinoid receptors in RA-sensitive and resistant NT2/D1 cells. The direct role of RARgamma in tumor differentiation is addressed in Specific Aim 4 by engineering lines to express a dominant-negative RARgamma construct. This research addresses the mechanisms of induced growth suppression and differentiation of human tumor cells. The successful completion of these specific aims should aid in the rational use of retinoids in cancer therapy and prevention.
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2004 — 2008 |
Spinella, Michael J |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Retinoid Tumor Differentiation Mechanisms
[unreadable] DESCRIPTION (provided by applicant): There is rapidly evolving evidence for beneficial retinoid actions in preventing or treating clinical tumors. Retinoids are established regulators of gene transcription via activation of retinoid receptors. The key targets of retinoid receptors are unknown. We have discovered a novel pathway of potential major biologic significance that is predicted to regulate retinoid signaling at the level of the receptor and also to provide cross-talk between retinoids and other nuclear receptor family members. Our previous microarray studies discovered that the nuclear receptor co-repressor, receptor interacting protein 140 (RIP140) is a novel direct target of all-trans retinoic acid (RA). RIP140 appears to belong to a novel class of nuclear receptor coregulators since it is able to suppress the function of various agonist-bound hormone receptors. [unreadable] [unreadable] We propose that the activation of RIP140 may be a general mechanism that regulates RA-mediated G1 arrest in diverse cell contexts through a mechanism of repressional cross-talk among nuclear receptor family members. Based on novel preliminary findings we have designed three specific aims that will establish whether RIP140 plays a critical role in two clinically important areas of retinoid cancer biology. During RA-induced terminal differentiation of human embyronal carcinoma, we will ask whether RA regulation of RIP140 constitutes a programmed negative feedback mechanism which limits the activation of retinoid receptors. In the second system, we will ask whether RIP140 mediates cross-talk between retinoid and estrogen signaling in human breast cancer. The novel hypothesis to be tested is that one mechanism by which retinoids regulate gene expression and biologic phenotype is by transrepression through direct activation of the retinoid target gene RIP140. The three specific aims are designed to probe the mechanistic consequence of RA induction of RIP140 and to establish whether RIP140 plays a central role in regulating retinoid-induced tumor cell differentiation and G1 arrest. We believe RIP140 is an excellent entry point to gain mechanistic insights on the role of coregulator dynamics in hormonal signaling across a broad range of hormones, tumors and tissues. [unreadable] [unreadable]
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2007 — 2008 |
Spinella, Michael J |
R21Activity Code Description: To encourage the development of new research activities in categorical program areas. (Support generally is restricted in level of support and in time.) |
Epigenetic Reprogramming of Malignant Stem Cells of the Testes
[unreadable] DESCRIPTION (provided by applicant): Embryonal carcinoma (EC) are the stem cells of testicular germ cell tumors (TGCTs), are pluripotent, and share remarkable genetic and biologic similarity to human ES cells. We contend that EC can be seen as an archetypal model of successfully treated, malignant cancer stem cells. Our efforts to define the molecular mechanisms of retinoic acid (RA) mediated tumor cell differentiation using global gene expression analysis and a unique system of RA-sensitive and RA-resistant human EC has led to our hypothesis that a critical determinant of loss of tumorigenicity of EC is epigenetic reprogramming. This evidence is based in part on a set of candidate pluripotency genes, including a polycomb group gene involved in Hox gene repression, PHC1/EDR1, that we discovered to be rapidly downregulated by RA at the lineage commitment window. We provide evidence that EDR1 and other pluripotency genes may be regulated by RA via RA-mediated downregulation of the master pluripotency factor Oct4. Interestingly, many of these RA-downregulated pluripotency genes reside on chromosome 12p, which is uniformly amplified in TGCTs. Hence, we propose that the malignant conversion of the normal primordial germ cell to the EC cell may involve "enforced" pluripotency with associated chromatin remodeling. The hypothesis to be tested is that RA-induced loss of stem cell renewal is in part due to transcriptional modulation of EDR1 leading to epigenetic reprogramming and lineage commitment of EC cells. The goal of this R21 Stem Cells and Cancer application is to begin to characterize histone modifications in EC cells associated with tumorigenic and curative potential. Our focus is the polycomb complex since alterations in this complex are known to be closely associated with a variety of human cancers and since we have shown that RA downregulates a specific polycomb gene EDR1 that is localized to the critical 12p amplicon in TGCTs. This will be accomplished through molecular, genetic and cell biologic approaches to complete the following specific aims. 1. To define polycomb-specific chromatin modifications of RA-sensitive EC and RA-resistant EC and to determine whether RA is a major morphogenic signal regulating polycomb-specific repression and cancer stem cell renewal. 2. To determine the role of the RR12 gene, EDR1, in RA-mediated, polycomb-specific reprogramming of cancer stem cell renewal in embryonal carcinoma. These studies are important because the unique "germ cell-like" epigenetics of human EC may be linked to the curability of TGCTs. Testicular germ cell tumors (TGCTs) are one of the few solid tumors curable with chemotherapy even when highly advanced, suggesting that the self-renewing, cancer stem cells of TGCTs are likely targeted during therapy. Completion of the aims of this grant will increase understanding of the genetics and biologic progression of TGCTs and may increase understanding of why these tumors are so curable when the vast majority of advanced solid tumors are not. This in turn may lead to new therapies that effectively target crucial cells within tumors, cancer stem cells. [unreadable] [unreadable] [unreadable] [unreadable]
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2014 — 2015 |
Spinella, Michael J |
R21Activity Code Description: To encourage the development of new research activities in categorical program areas. (Support generally is restricted in level of support and in time.) |
New Cancer Therapeutic Target
DESCRIPTION (provided by applicant): The median survival of patients with glioblastoma (GBM) is 12-15 months. Extending the life of individuals with this disease is a critical unmet need. Clearly more effective therapies are needed and the identification of new targets is a key strategy to accelerate progress towards this goal. This application is based on our unique discovery of a new candidate kinase target for GBM called STK17A. STK17A is a novel member of the DAP family of serine/threonine protein kinases. Our preliminary data directly links STK17A to survival of GBM patients. STK17A is highly overexpressed in GBM. STK17A overexpression and increased copy number is associated with a significant survival disadvantage for patients with glioma. Knockdown of STK17A in established and primary human GBM results in a decrease in proliferation and sensitized cells to nutritional stress. Knockdown of STK17A is associated with a marked decrease in ULK1, a critical rate-limiting component of autophagy and STK17A knockdown represses autophagy in response to cytotoxic and nutritional stress. Small molecular weight inhibitors of STK17A also inhibit the growth/survival of GBM cells. STK17A is an entirely new candidate kinase target for GBM that our lab has uncovered. The broad, long-term goal of this project is to determine the role of STK17A in promoting GBM proliferation and survival and to discover whether targeting STK17A is a promising strategy to combat GBM which is resistant to current forms of therapy. Our hypothesis is that STK17A is an exciting and new therapeutic target and prognostic biomarker in GBM and that overexpression of STK17A promotes progression and growth of GBM and promotes autophagy-mediated tumor cell survival upon nutrient deprivation and therapy-induced genotoxic stress. Translational studies using clinical samples and in vitro and in vivo models will mechanistically test our hypothesis. This application is innovative since it is based on new data generated by our laboratory on a novel serine/threonine kinase that has not previously been linked to cancer or tumor cell chemosensitivity. The proposed aims are significant since they have the potential to introduce the field to an entirely new GBM target that could lead to development of new therapies for GBM and other cancers and provide a new strategy to sensitize cancers to existing therapies. This project will also lead to findings to support targetig autophagy as a general strategy to combat cancer and provides a target in which to do so in GBM. Through the unique resources available and expert collaborators we are poised to make significant contributions to our understanding of STK17A as a prognostic marker and therapeutic target for GBM.
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