SUMMARY Recurrent mutations in histone modifying enzymes imply key roles in tumorigenesis yet their functional relevance is largely unknown. Here we show that JARID1B, encoding a histone H3 lysine 4 (H3K4) demethylase, is frequently amplified and overexpressed in luminal breast tumors and a somatic mutation in a basal-like breast cancer results in the gain of unique chromatin binding and luminal expression and splicing patterns. Downregulation of JARID1B in luminal cells induces basal genes expression and growth arrest, which is rescued by TGFβ pathway inhibitors. Integrated JARID1B chromatin binding, H3K4 methylation, and expression profiles suggest a key function for JARID1B in luminal cell-specific expression programs. High luminal JARID1B activity is associated with poor outcome in patients with hormone receptor positive breast tumors.

p73 has been identi®ed as a protein which shares signi®cant homology with the tumor suppressor p53. We found two new types of splicing variant mRNAs for p73 expressed in MCF-7 cells which we named p73g and e. Sequence analysis revealed that these mRNAs encode variant p73 proteins bearing distinct carboxy-terminal structures, which are also di erent from the previously reported variants p73a and b. The mRNAs encoding p73g and e as well as a and b were con®rmed to be expressed in normal human tissues in varied patterns. All of these splicing variants activated promoter with the p53-binding consensus sequence, but to di erent degrees. Furthermore, suppressive e ects of p73a, g and e, but not b, on endogenous p53 activity were observed when transiently expressed in HepG2 and MCF-7 cells. These results suggested that the carboxy-terminal regions of p73 which were altered by alternative splicing a ect these transactivation abilities and modulate the functions of p73 molecules.

Dysregulation of lysine (K)-specific demethylase 1A (LSD1), also known as KDM1A, has been implicated in the development of various cancers, including leukemia. Here, we describe the antileukemic activity and mechanism of action of T-3775440, a novel irreversible LSD1 inhibitor. Cell growth analysis of leukemia cell lines revealed that acute erythroid leukemia (AEL) and acute megakaryoblastic leukemia cells (AMKL) were highly sensitive to this compound. T-3775440 treatment enforced transdifferentiation of erythroid/megakaryocytic lineages into granulomonocytic-like lineage cells. Mechanistically, T-3775440 disrupted the interaction between LSD1 and growth factor-independent 1B (GFI1B), a transcription factor critical for the differentiation processes of erythroid and megakaryocytic lineage cells. Knockdown of LSD1 and GFI1B recapitulated T-3775440-induced transdifferentiation and cell growth suppression, highlighting the significance of LSD1-GFI1B axis inhibition with regard to the anti-AML effects of T-3775440. Moreover, T-3775440 exhibited significant antitumor efficacy in AEL and AMKL xenograft models. Our findings provide a rationale for evaluating LSD1 inhibitors as potential treatments and indicate a novel mechanism of action against AML, particularly AEL and AMKL. Mol Cancer Ther; 16(2); 273-84. ©2016 AACR.

The epidermal growth factor receptor (EGFR) family plays a critical role in vital cellular processes and in various cancers. Known EGFR inhibitors exhibit distinct antitumor responses against the various EGFR mutants associated with nonsmall-cell lung cancer. The L858R mutation enhances clinical sensitivity to gefitinib and erlotinib as compared with wild type and reduces the relative sensitivity to lapatinib. In contrast, the T790M mutation confers drug resistance to gefitinib and erlotinib. We determined crystal structures of the wild-type and T790M/L858R double mutant EGFR kinases with reversible and irreversible pyrrolo[3,2-d]pyrimidine inhibitors based on analogues of TAK-285 and neratinib. In these structures, M790 adopts distinct conformations to accommodate different inhibitors, whereas R858 allows conformational variations of the activation loop. These results provide structural insights for understanding the structure-activity relationships that should contribute to the development of potent inhibitors against drug-sensitive or -resistant EGFR mutations.

Protein arginine methyltransferases (PRMTs) regulate diverse biological processes and are increasingly being recognized for their potential as drug targets. Here we report the discovery of a potent, selective, and cell-active chemical probe for PRMT7. SGC3027 is a cell permeable prodrug, which in cells is converted to SGC8158, a potent, SAM-competitive PRMT7 inhibitor. Inhibition or knockout of cellular PRMT7 results in drastically reduced levels of arginine monomethylated HSP70 family stress-associated proteins. Structural and biochemical analyses reveal that PRMT7-driven in vitro methylation of HSP70 at R469 requires an ATP-bound, open conformation of HSP70. In cells, SGC3027 inhibits methylation of both constitutive and inducible forms of HSP70, and leads to decreased tolerance for perturbations of proteostasis including heat shock and proteasome inhibitors. These results demonstrate a role for PRMT7 and arginine methylation in stress response.

T-3775440 is an irreversible inhibitor of the chromatin demethylase LSD1, which exerts antiproliferative effects by disrupting the interaction between LSD1 and GFI1B, a SNAG domain transcription factor, inducing leukemia cell transdifferentiation. Here, we describe the anticancer effects and mechanism of action of T-3775440 in small-cell lung cancer (SCLC). T-3775440 inhibited proliferation of SCLC cells and retarded SCLC tumor growth T-3775440 disrupted the interaction between LSD1 and the transcriptional repressor INSM1, thereby inhibiting expression of neuroendocrine-associated genes, such as INSM1 silencing phenocopied the effects of T-3775440 on gene expression and cell proliferation, consistent with the likelihood T-3775440 mediated its effects in SCLC by inhibiting INSM1. T-3775440 also inhibited proliferation of an SCLC cell line that overexpressed GFI1B, rather than INSM1, by disrupting the interaction between LSD1 and GFI1B. Taken together, our results argue that LSD1 plays an important role in neuroendocrine-associated transcription and cell proliferation of SCLC via interactions with the SNAG domain proteins INSM1 and GFI1B. Targeting these critical interactions with LSD1 inhibitors offers a novel rational strategy to therapeutically manage SCLC..

The mechanisms of the molecular and dissociative adsorption of formic acid HCOOH on a ZnO(101̄0) surface were investigated by means of the ab initio molecular orbital method using a Zn4O4 cluster embedded in an electrostatic field represented by 464 point charges at the crystal ZnO lattice positions. cis-Formic acid molecularly adsorbs on a ZnO(101̄0) surface without activation energy. It dissociates into a formate anion HCOO- and a proton H+ with an activation energy of 11.7 kcal/mol. The formate anion is geometrically stable in the bridging structure of two Zn atoms and the unidentate structure of a Zn atom interacting with a surface OH species. The adsorption energy is about 80 kcal/mol for both structures. In contrast, the bidentate structure is about 24 kcal/mol less stable. Possible reaction pathways for the dissociation of the O−H bond of cis-formic acid were also examined. trans-Formic acid is dissociatively adsorbed on a ZnO(101̄0) surface to form a formate anion and a surface OH species without activation energy. The initial formate anion generated from trans-formic acid continues to interact with the surface OH species. This interaction produces the stability of the unidentate structure. Interconversion between the unidentate and bridging structures was also examined. The formate anion can be easily tilted on the surface by a small perturbation, leading to increased interaction between the formate species and the surface.

Since the commercialization of rechargeable Li ion batteries in the early 1990 s, the performance of these devices has continually improved. In such batteries, graphite is typically used as the negative electrode and the present work examined the reaction mechanisms at graphite negative electrodes based on operando synchrotron X-ray diffraction analyses during charge/discharge. The resulting in-plane diffraction patterns of the Li-intercalated graphite permitted a detailed analysis of changes in the three-dimensional structure of the electrode. As the intercalation proceeded from a dilute stage 1 (with less Li intercalation) to a final stage 1 (the formation of LiC6), the material transitioned from a random in-plane structure to a p(√3 × √3)R30° in-plane structure via a superlattice based on a p(3 × 3)R0° in-plane structure. The data also indicate that a series of superlattices was formed during the reaction of the electrode as a result of successive rearrangements, depending on the amount of Li intercalated into the graphite.