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Supplementary Figure 1 from Peroxisome Proliferator-Activated Receptor-δ Induces Cell Proliferation by a Cyclin E1–Dependent Mechanism and Is Up-regulated in Thyroid Tumors

Supplementary Methods from Cyclin D2–Cyclin-Dependent Kinase 4/6 Is Required for Efficient Proliferation and Tumorigenesis following Apc Loss

Supplementary Figure Legends 1-4 from Cyclin D2–Cyclin-Dependent Kinase 4/6 Is Required for Efficient Proliferation and Tumorigenesis following Apc Loss

Supplementary Figures 1-4 from Cyclin D2–Cyclin-Dependent Kinase 4/6 Is Required for Efficient Proliferation and Tumorigenesis following Apc Loss

Peroxisome proliferator-activated receptors (PPARs) are lipid-sensing nuclear receptors that have been implicated in multiple physiologic processes including cancer. Here, we determine that PPARδ induces cell proliferation through a novel cyclin E1–dependent mechanism and is up-regulated in many human thyroid tumors. The expression of PPARδ was induced coordinately with proliferation in primary human thyroid cells by the activation of serum, thyroid-stimulating hormone/cyclic AMP, or epidermal growth factor/mitogen-activated protein kinase mitogenic signaling pathways. Engineered overexpression of PPARδ increased thyroid cell number, the incorporation of bromodeoxyuridine, and the phosphorylation of retinoblastoma protein by 40% to 45% in just 2 days, one usual cell population doubling. The synthetic PPARδ agonist GW501516 augmented these PPARδ proliferation effects in a dose-dependent manner. Overexpression of PPARδ increased cyclin E1 protein by 9-fold, whereas knockdown of PPARδ by small inhibitory RNA reduced both cyclin E1 protein and cell proliferation by 2-fold. Induction of proliferation by PPARδ was abrogated by knockdown of cyclin E1 by small inhibitory RNA in primary thyroid cells and by knockout of cyclin E1 in mouse embryo fibroblasts, confirming a cyclin E1 dependence for this PPARδ pathway. In addition, the mean expression of native PPARδ was increased by 2-fold to 5-fold (P < 0.0001) and correlated with that of the in situ proliferation marker Ki67 (R = 0.8571; P = 0.02381) in six different classes of benign and malignant human thyroid tumors. Our experiments identify a PPARδ mechanism that induces cell proliferation through cyclin E1 and is regulated by growth factor and lipid signals. The data argue for systematic investigation of PPARδ antagonists as antineoplastic agents and implicate altered PPARδ–cyclin E1 signaling in thyroid and other carcinomas. [Cancer Res 2008;68(16):6578–86]

Inactivation of the Apc gene is recognized as the key early event in the development of sporadic colorectal cancer (CRC), where its loss leads to constitutive activation of β-catenin/T-cell factor 4 signaling and hence transcription of Wnt target genes such as c-Myc. Our and other previous studies have shown that although cyclin D1 is required for adenoma formation, it is not immediately upregulated following Apc loss within the intestine, suggesting that proliferation following acute Apc loss may be dependent on another D-type cyclin. In this study, we investigated the expression and functional relevance of cyclin D2 following Apc loss in the intestinal epithelium. Cyclin D2 is upregulated immediately following Apc loss, which corresponded with a significant increase in cyclin-dependent kinase 4 (CDK4) and hyperphosphorylated Rb levels. Deficiency of cyclin D2 resulted in a reduction in enterocyte proliferation and crypt size within Apc-deficient intestinal epithelium. Moreover, cyclin D2 dramatically reduced tumor growth and development in ApcMin/+ mice. Importantly, cyclin D2 knockout did not affect proliferation of normal enterocytes, and furthermore, CDK4/6 inhibition also suppressed the proliferation of adenomatous cells and not normal cells from ApcMin/+ mice. Taken together, these results indicate that cyclin D–CDK4/6 complexes are required for the efficient proliferation of cells with deregulated Wnt signaling, and inhibiting this complex may be an effective chemopreventative strategy in CRC. Cancer Res; 70(20); 8149–58. ©2010 AACR.

Supplementary Figure 2 from Peroxisome Proliferator-Activated Receptor-δ Induces Cell Proliferation by a Cyclin E1–Dependent Mechanism and Is Up-regulated in Thyroid Tumors

Background Nuclear‐to‐mitochondrial communication regulating gene expression and mitochondrial function is a critical process following cardiac ischemic injury. In this study, we determined that cyclin C, a component of the Mediator complex, regulates cardiac and mitochondrial function in part by modifying mitochondrial fission. We tested the hypothesis that cyclin C functions as a transcriptional cofactor in the nucleus and a signaling molecule stimulating mitochondrial fission in response to stimuli such as cardiac ischemia. Methods and Results We utilized gain‐ and loss‐of‐function mouse models in which the CCNC (cyclin C) gene was constitutively expressed (transgenic, CycC cTg) or deleted (knockout, CycC cKO) in cardiomyocytes. The knockout and transgenic mice exhibited decreased cardiac function and altered mitochondria morphology. The hearts of knockout mice had enlarged mitochondria with increased length and area, whereas mitochondria from the hearts of transgenic mice were significantly smaller, demonstrating a role for cyclin C in regulating mitochondrial dynamics in vivo. Hearts from knockout mice displayed altered gene transcription and metabolic function, suggesting that cyclin C is essential for maintaining normal cardiac function. In vitro and in vivo studies revealed that cyclin C translocates to the cytoplasm, enhancing mitochondria fission following stress. We demonstrated that cyclin C interacts with Cdk1 (cyclin‐dependent kinase 1) in vivo following ischemia/reperfusion injury and that, consequently, pretreatment with a Cdk1 inhibitor results in reduced mitochondrial fission. This finding suggests a potential therapeutic target to regulate mitochondrial dynamics in response to stress. Conclusions Our study revealed that cyclin C acts as a nuclear‐to‐mitochondrial signaling factor that regulates both cardiac hypertrophic gene expression and mitochondrial fission. This finding provides new insights into the regulation of cardiac energy metabolism following acute ischemic injury.

During development of the vertebrate CNS, the basic helix-loop-helix (bHLH) transcription factor Olig2 sustains replication competence of progenitor cells that give rise to neurons and oligodendrocytes. A pathological counterpart of this developmental function is seen in human glioma, wherein Olig2 is required for maintenance of stem-like cells that drive tumor growth. The mitogenic/gliomagenic functions of Olig2 are regulated by phosphorylation of a triple serine motif (S10, S13, and S14) in the amino terminus. Here, we identify a set of three serine/threonine protein kinases (glycogen synthase kinase 3α/β [GSK3α/β], casein kinase 2 [CK2], and cyclin-dependent kinases 1/2 [CDK1/2]) that are, collectively, both necessary and sufficient to phosphorylate the triple serine motif. We show that phosphorylation of the motif itself serves as a template to prime phosphorylation of additional serines and creates a highly charged "acid blob" in the amino terminus of Olig2. Finally, we show that small molecule inhibitors of this forward-feeding phosphorylation cascade have potential as glioma therapeutics.

D-type cyclins integrate mitogen-dependent signals to enforce progression through the first gap phase (G1) of the cell division cycle. In simplest terms, three mammalian D-type cyclins (D1, D2, and D3), induced in a cell lineage-specific fashion in response to extracellular signals, interact with two cyclin-dependent kinases (CDK4 and CDK6) to form holoenzyme complexes that phosphorylate the retinoblastoma protein (RB). In turn, RB phosphorylation, reinforced by other CDKs expressed later in G1 phase, inactivates the suppressive effects of RB on transcription factors that induce genes required for DNA replication. All steps in the life history of individual D-type cyclins, including their transcriptional induction, translation, assembly with CDK4 and CDK6, and their rapid turnover via ubiquitin-mediated proteolysis, are governed by mitogen signaling. Hence, progression through the G1 phase of the mammalian cell cycle is tied to extracellular signals that ultimately influence cell division. Analysis of phenotypes of mice lacking D cyclins has highlighted their individual and combinatorial lineage-specific activities during mammalian development. The genes encoding D-type cyclins and their dependent kinases, CDK4 and CDK6, are proto-oncogenes implicated in many forms of cancer. Genetic or biochemical disruption of cyclin D-dependent CDK signaling can restrain cancer development and progression. Here, we highlight the founding discoveries.

Prior to the massive beta cell demise that leads to autoimmune diabetes (Type 1 Diabetes or T1D), profound profiling changes are imprinted onto the beta cell by an aggressive pro-inflammatory environment that interferes negatively with cell functionality and viability. Ourgoal is to determine key signaling pathways altered in beta cells by the autoimmune assault that are responsible for T1D progression. To this end we have used the T1D-prone NOD (Non Obese Diabetic) mouse model. We have identified several candidate genes the expression of which is altered in the NOD isletendocrine cells prior to the diabetes onset. Interestingly, several of these genes are related to cell cycle progression and are downregulated due to the insulitic attack to the islet. One of these genes is cyclin D3, a D-type cyclin that complexes with either Cdk4 or Cdk6 topromote G1/S cycle progression. The cyclin D3 promoter has binding sequences to NF-kB. However, we have reported that cyclin D3 protects beta cells against cytokine-induced apoptosis and is required for proper beta cell function in a cell-cycle independent fashion. Cdk11 is also affected by inflammation in islet cells and is a cyclin-dependent kinase which is involved in transcription, mitosis and apoptosis. The natural partners of Cdk11 are L-type cyclins, but cyclin D3 has been reported to interact with Cdk11 too. We have addressed whether cdk11 downregulationis responsible for beta cell death.

In this issue of Genes & Development, Besson et al. (2007) report phenotypic characteristics of a novel knock-in mouse strain expressing a mutant allele of the cell cycle inhibitor p27 KiP1 that has both common and unique features when compared with a null allele. The new studies provide the first direct in vivo evidence that in addition to its role as a tumor suppressor, p27 Kip1 also functions as an oncogene. The work also suggests that p27 Kip1 oncogenic activity leads to aberrant stem and progenitor cell expansion in the lung and retina, respectively. Thus, p27 KiP1 's new "dark side" may serve an oncogenic function that operates in less specialized cell types to influence tumorigenesis. creased patient survival (Slingerland and Pagano 2000). Germline mutation of p27 Kip1 was also recently described in a subset of MEN (Multiple Endocrine Neoplasia) syndrome patients in humans, as well as in rats with the related MENX syndrome (Pellegata et al. 2006). p27 Kip1 -null mice develop organomegaly and pituitary adenomas (Fero et al. 1996; Kiyokawa et al. 1996; Nakayama et al. 1996). The most simplistic explanation of the phenotypes was that in p27 Kip1-/- mice, the deregulated CDK2 kinase was responsible for these symptoms. However, recent observations that ablation of CDK2 in p27 Kip1 -null background did not mitigate the phenotypes of p27 Kip1 deficiency clearly shows that p27 Kip1 can act independently of CDK2, likely in part by hyperactivating CDK1 (Aleem et al. 2005; Martin et al. 2005).

Mutations in DNA repair genes show peculiar defects in central nervous system morphogenesis characterized by dramatic cerebellar dysmorphia with relatively preserved forebrain development. Loss of ...

A fundamental aspect of cancer is dysregulated cell cycle control. Unlike normal cells that only proliferate when compelled to do so by developmental or other mitogenic signals in response to tissue growth needs, the proliferation of cancer cells proceeds essentially unchecked. This does not mean that cancer cell cycles are necessarily different from those found in normal cycling cells, but rather implies that cancer cells proliferate because they are no longer subject to proliferation-inhibitory influences arising from the stroma or from gene expression pattern changes consequent to 'terminal' differentiation, nor do they necessarily require extrinsic growth factors to recruit them into or maintain their proliferative state. Finally, cancer cells have also often avoided normal controls linked to cell cycle progression that halt proliferation in the presence of damaged DNA or other physiological insults. The result of these alterations is the inappropriate proliferation commonly associated with cancerous tumor formation. This review will summarize the current understanding of dysregulation of the G0/G1-to-S-phase transition in cancer cells, with particular emphasis on recent in vivo studies that suggest a need to rethink existing models of cell cycle control in development and tumorigenesis.

Type 1 diabetes (T1D) is an autoimmune disease caused by pancreatic beta cells demise due to the attack of self-lymphocyte repertoire. We aim to identify molecular entities targeted by the autoimmune assault to pancreatic beta cells that are causally related to T1D progression. The proinflammatory biological niche in which beta cells are immersed during the autoimmune insult promotes deep phenotypical changes crucial for the pathogenic process. These changes lead mainly to beta cell fitness impairment, cell cycle intervention and apoptosis triggering. By using the Microarray technology we identified a series of genes the expression of which is altered in the islet endocrine cells prior to diabetes onset in the NOD (Non Obese Diabetic) mice. One of those genes encodes for cyclin D3 that triggers cell cycle progression through G1 phase towards the S phase. Cyclin D3 can also bind certain transcription factors and activate inflammation process and development of the T cells (NFκB, GATA). The cyclin D3 promoter has binding sequences to NFκB a transcription factor linked to the action of T1D-related proinflammatory cytokines such as IL-1beta and TNFalpha. We found that cyclin D3 is the only D-type cyclin the expression of which is regulated by inflammation in NOD endocrine islet cells. Moreover we found that cyclin D3 protects beta cells against cytokine-induced apoptosis and is required for proper beta cell function. Moreoever, we observed that CDK11, another cell-cycle related gene that interacts with cyclin D3, is also regulated by inflammation in endocrine islet cells. We have assessed whether there is a causal relationship between the coordinated differential expression of both genes during the insulitic assault and diabetes onset

Inactivation of the Apc gene is recognized as the key early event in the development of sporadic colorectal cancer (CRC), where its loss leads to constitutive activation of β-catenin/T-cell factor 4 signaling and hence transcription of Wnt target genes such as c-Myc. Our and other previous studies have shown that although cyclin D1 is required for adenoma formation, it is not immediately upregulated following Apc loss within the intestine, suggesting that proliferation following acute Apc loss may be dependent on another D-type cyclin. In this study, we investigated the expression and functional relevance of cyclin D2 following Apc loss in the intestinal epithelium. Cyclin D2 is upregulated immediately following Apc loss, which corresponded with a significant increase in cyclin-dependent kinase 4 (CDK4) and hyperphosphorylated Rb levels. Deficiency of cyclin D2 resulted in a reduction in enterocyte proliferation and crypt size within Apc-deficient intestinal epithelium. Moreover, cyclin D2 dramatically reduced tumor growth and development in ApcMin/+ mice. Importantly, cyclin D2 knockout did not affect proliferation of normal enterocytes, and furthermore, CDK4/6 inhibition also suppressed the proliferation of adenomatous cells and not normal cells from ApcMin/+ mice. Taken together, these results indicate that cyclin D–CDK4/6 complexes are required for the efficient proliferation of cells with deregulated Wnt signaling, and inhibiting this complex may be an effective chemopreventative strategy in CRC. Cancer Res; 70(20); 8149–58. ©2010 AACR.

Peroxisome proliferator-activated receptors (PPARs) are lipid-sensing nuclear receptors that have been implicated in multiple physiologic processes including cancer. Here, we determine that PPARδ induces cell proliferation through a novel cyclin E1–dependent mechanism and is up-regulated in many human thyroid tumors. The expression of PPARδ was induced coordinately with proliferation in primary human thyroid cells by the activation of serum, thyroid-stimulating hormone/cyclic AMP, or epidermal growth factor/mitogen-activated protein kinase mitogenic signaling pathways. Engineered overexpression of PPARδ increased thyroid cell number, the incorporation of bromodeoxyuridine, and the phosphorylation of retinoblastoma protein by 40% to 45% in just 2 days, one usual cell population doubling. The synthetic PPARδ agonist GW501516 augmented these PPARδ proliferation effects in a dose-dependent manner. Overexpression of PPARδ increased cyclin E1 protein by 9-fold, whereas knockdown of PPARδ by small inhibitory RNA reduced both cyclin E1 protein and cell proliferation by 2-fold. Induction of proliferation by PPARδ was abrogated by knockdown of cyclin E1 by small inhibitory RNA in primary thyroid cells and by knockout of cyclin E1 in mouse embryo fibroblasts, confirming a cyclin E1 dependence for this PPARδ pathway. In addition, the mean expression of native PPARδ was increased by 2-fold to 5-fold (P < 0.0001) and correlated with that of the in situ proliferation marker Ki67 (R = 0.8571; P = 0.02381) in six different classes of benign and malignant human thyroid tumors. Our experiments identify a PPARδ mechanism that induces cell proliferation through cyclin E1 and is regulated by growth factor and lipid signals. The data argue for systematic investigation of PPARδ antagonists as antineoplastic agents and implicate altered PPARδ–cyclin E1 signaling in thyroid and other carcinomas. [Cancer Res 2008;68(16):6578–86]

Mice likely represent the most-studied mammalian organism, except for humans. Genetic engineering in embryonic stem cells has allowed derivation of mouse strains lacking particular cell cycle proteins. Analyses of these mutant mice, and cells derived from them, facilitated the studies of the functions of cell cycle apparatus at the organismal and cellular levels. In this review, we give some background about the cell cycle progression during mouse development. We next discuss some insights about in vivo functions of the cell cycle proteins, gleaned from mouse knockout experiments. Our text is meant to provide examples of the recent experiments, rather than to supply an extensive and complete list.

Abstract 914 Cell cycle regulators could be differentially used among self–renewing stem cells, rapidly expanding progenitor cells, and terminally differentiated cells those clonally replicate. Cyclin A is a regulatory subunit for cyclin dependent kinase (Cdk) 1 and Cdk2, and it drives S phase progression as well as transition to G2/M phase in cell cycle. We have previously reported that cyclin A2 is not required for fibroblast replication but it is indispensable in maintenance of self-renewing stem cells, including embryonic stem cells and hematopoietic stem cells (HSCs) (Cell 138 2009). The question is whether cyclin A2 plays a role in proliferation of hematopoietic progenitors downstream of the HSC. Here, we further assessed the requirement of cyclin A2 in non-self-renewing hematopoietic progenitors. Quantitative RT-PCR analysis showed that cyclin A2 was expressed in hematopoietic progenitor cells as well as stem cells, and its expression level is highest in lymphoid-committed progenitor stages of both T and B cell lineages. Thus, in order to test the role of cylin A2 in early lymphopoiesis, we crossed cyclin A2 floxed mice with Rag1-Cre knock-in mice. Because recombination activating gene (RAG)-1 is essential for generation of pre-BCRs and pre-TCRs that are critical for expansion of B and T lymphoid progenitor cells, respectively, we hypothesized that the requirement of Cyclin A2 in early lymphopoiesis can be assessed in this system. As we expected, the Rag1-Cre cyclin A2 floxed/floxed mice were viable, and have normal numbers of HSCs and myeloid progenitors. They, however, displayed severe reduction of mature T and B cell numbers that were only 1/100 - 1/10 of wild-type controls. The number of common lymphoid progenitor was unchanged, but there were severely reduced preB cells in bone marrow and T cell progenitors from CD4-CD8- double negative stage in thymus. Furthermore, cell cycle analysis shows that the Cyclin A2 disrupted progenitors are unable to progress from S to G2/M phase, and in vitro culture clearly showed that those progenitors are unable to proliferate and resulted in apoptosis. These findings clearly demonstrate that cyclin A2 is indispensable not only for self-renewing HSCs, but also for proliferation of T and B cell progenitors. Disclosures: No relevant conflicts of interest to declare.