Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal human cancers and shows resistance to any therapeutic strategy used. Here we tested small-molecule inhibitors targeting chromatin regulators as possible therapeutic agents in PDAC. We show that JQ1, an inhibitor of the bromodomain and extraterminal (BET) family of proteins, suppresses PDAC development in mice by inhibiting both MYC activity and inflammatory signals. The histone deacetylase (HDAC) inhibitor SAHA synergizes with JQ1 to augment cell death and more potently suppress advanced PDAC. Finally, using a CRISPR-Cas9–based method for gene editing directly in the mouse adult pancreas, we show that de-repression of p57 (also known as KIP2 or CDKN1C) upon combined BET and HDAC inhibition is required for the induction of combination therapy–induced cell death in PDAC. SAHA is approved for human use, and molecules similar to JQ1 are being tested in clinical trials. Thus, these studies identify a promising epigenetic-based therapeutic strategy that may be rapidly implemented in fatal human tumors.

The nuclear factor of activated T cell (NFAT) proteins are a family of Ca 2 þ /calcineurin-responsive transcription factors primarily recognized for their central roles in T lymphocyte activation and cardiac valve development. We demonstrate that NFATc1 is commonly overexpressed in pancreatic carcinomas and enhances the malignant potential of tumor cells through transcriptional activation of the c-myc oncogene. Activated NFATc1 directly binds to a specific element within the proximal c-myc promoter and upregulates c-myc transcription, ultimately resulting in increased cell proliferation and enhanced anchorageindependent growth. Conversely, c-myc transcription and anchorage-dependent and -independent cell growth is significantly attenuated by inhibition of Ca 2 þ /calcineurin signaling or siRNA-mediated knock down of NFATc1 expression. Together, these results demonstrate that ectopic activation of NFATc1 and the Ca 2 þ /calcineurin signaling pathway is an important mechanism of oncogenic c-myc activation in pancreatic cancer.

Sp1-like proteins are defined by three highly homologous C 2 H 2 zinc finger motifs that bind GC-rich sequences found in the promoters of a large number of genes essential for mammalian cell homeostasis. Here we report that TIEG2, a transforming growth factor ␤-inducible Sp1-like protein with antiproliferative functions, represses transcription through recruitment of the mSin3A-histone deacetylase complex. The interaction of TIEG2 with mSin3A is mediated by an alpha-helical repression motif (␣-HRM) located within the repression domain (R1) of TIEG2. This ␣-HRM specifically associates with the second paired amphipathic helix (PAH2) domain of mSin3A. Mutations in the TIEG2 ␣-HRM domain that disrupt its helical structure abolish its ability to both bind mSin3A and repress transcription. Interestingly, the ␣-HRM is conserved in both the TIEG (TIEG1 and TIEG2) and BTEB (BTEB1, BTEB3, and BTEB4) subfamilies of Sp1-like proteins. The ␣-HRM from these proteins also mediates direct interaction with mSin3A and represses transcription. Surprisingly, we found that the ␣-HRM of the Sp1-like proteins characterized here exhibits structural and functional resemblance to the Sin3A-interacting domain previously described for the basic helix-loop-helix protein Mad1. Thus, our study defines a mechanism of transcriptional repression via the interactions of the ␣-HRM with the Sin3-histone deacetylase complex that is utilized by at least five Sp1-like transcriptional factors. More importantly, we demonstrate that a helical repression motif which mediates Sin3 interaction is not an exclusive structural and functional characteristic of the Mad1 subfamily but rather has a wider functional impact on transcriptional repression than previously demonstrated.The Sp1-like family of transcription factors is characterized by the presence of three highly homologous C-terminal zinc finger motifs that are capable of binding GC-rich DNA sequences. These GC-rich motifs are present in the promoters of more than a thousand different gene products (10,17,21,23). Currently, the Sp1-like proteins identified contain at least 16 members that can be classified into several subgroups, including Sp (Sp1, Sp2, Sp3, and Sp4), BTEB (BTEB1), KLF (BKLF, BKLF3, EKLF, GKLF, BTEB2/IKLF, and LKLF), CPBP (CPBP and UKLF), TIEG (TIEG1 and TIEG2), and Ap-2rep. The detailed nomenclature and classification of these proteins can be found in several recent reviews (7,8,26,34). Several new members, including BTEB3 (J. Kaczynski et al., unpublished data), BTEB4 (A. Conley et al., unpublished data), Sp5 (14), and SP6/KLF14 (27), have recently been added to this growing family of proteins. Because many of the genes essential for the regulation of cell growth (6, 18, 28, 30), differentiation (2, 9), and apoptosis (21, 32) contain Sp1-like binding sites, it is not surprising that members of the Sp1 family are important regulators of mammalian cell homeostasis. Additionally, Sp1-like proteins are critical for normal development. Studies with animal models have shown that disruption o...

Macroautophagy is an evolutionarily conserved cellular process involved in the clearance of proteins and organelles. Although the cytoplasmic machinery that orchestrates autophagy induction during starvation, hypoxia, or receptor stimulation has been widely studied, the key epigenetic events that initiate and maintain the autophagy process remain unknown. Here we show that the methyltransferase G9a coordinates the transcriptional activation of key regulators of autophagosome formation by remodeling the chromatin landscape. Pharmacological inhibition or RNA interference (RNAi)-mediated suppression of G9a induces LC3B expression and lipidation that is dependent on RNA synthesis, protein translation, and the methyltransferase activity of G9a. Under normal conditions, G9a associates with the LC3B, WIPI1, and DOR gene promoters, epigenetically repressing them. However, G9a and G9a-repressive histone marks are removed during starvation and receptor-stimulated activation of naive T cells, two physiological inducers of macroautophagy. Moreover, we show that the c-Jun N-terminal kinase (JNK) pathway is involved in the regulation of autophagy gene expression during naive-T-cell activation. Together, these findings reveal that G9a directly represses genes known to participate in the autophagic process and that inhibition of G9a-mediated epigenetic repression represents an important regulatory mechanism during autophagy.A utophagy is an evolutionarily conserved catabolic process in eukaryotes that involves lysosomal degradation of cellular components, including long-lived proteins and organelles. There are four main forms of autophagy: macroautophagy (referred to here as autophagy), selective autophagy, microautophagy, and chaperone-mediated autophagy (1-4). Autophagy serves as an adaptive response to protect cells or organisms during periods of cellular stress, such as nutrient deprivation. In addition, autophagy can participate in several cellular and developmental processes, including homeostasis, clearance of intracellular pathogens, and immunity (1). Due to its fundamental importance for cellular survival, autophagy regulation has been implicated in several human diseases, such as cancer and neurodegenerative disorders (2, 5).Autophagy initiation involves the de novo synthesis of a double-membrane structure known as the phagophore, which ultimately elongates and closes to sequester cytoplasmic proteins and organelles, forming the autophagosome. The autophagosome subsequently undergoes a stepwise maturation process that culminates in its fusion with acidified endosomal/lysosomal vesicles, resulting in the degradation of its contents into useful biomolecules (2). A screen of yeast mutants unable to survive under nitrogen deprivation characterized a network of autophagy-related (ATG) genes (6). Mammalian homologues of these ATGs were later identified and shown to participate during distinct steps of autophagy. For example, microtubule-associated protein light chain 3 (LC3B) undergoes lipidation and is recruited to the pha...