Coumarins are plant-derived secondary metabolites. The crystal structure of three coumarins—bergamottin, osthole and fraxidin—are described and we analyze intermolecular interactions and their role in crystal formation. Bergamottin is a furanocoumarin found in citrus plants, which is a strong inhibitor of the principal human metabolizing enzyme, cytochrome P450 3A4 (CYP3A4). The crystal structure determinations of three coumarins give us the geometrical parameters and reveal the parallel-displaced π–π stacking and hydrogen bonding intermolecular interactions used for molecular assembly in the crystal structure. A quite strong (less than 3.4 Å) stacking interaction of bergamottin appears to be a determining feature that distinguishes it from other coumarins studied in this work. Our DFT computational studies on the three natural products of the same coumarin family docked into the active site of CYP3A4 (PDB 4D78) show different behavior for these coumarins at the active site. When the substrate is bergamottin, the importance of π-π stacking and hydrogen bonding, which can anchor the substrate in place, appears fundamental. In contrast, fraxidin and osthole show carbonyl coordination to iron. Our docking calculations show that the bergamottin tendency towards π–π stacking is important and likely influences its interactions with the heme group of CYP3A4.

Background: miR-33 family members are well characterized regulators of cellular lipid levels in mammals. Previous studies have shown that overexpression of miR-33 in Drosophila melanogaster leads to elevated triacylglycerol (TAG) levels in certain contexts. Although loss of miR-33 in flies causes subtle defects in larval and adult ovaries, the effects of miR-33 deficiency on lipid metabolism and other phenotypes impacted by metabolic state have not yet been characterized. Results:We found that loss of miR-33 predisposes flies to elevated TAG levels, and we identified genes involved in TAG synthesis as direct targets of miR-33, including atpcl, midway, and Akt1. miR-33 mutants survived longer upon starvation but showed greater sensitivity to an oxidative stressor. We also found evidence that miR-33 is a negative regulator of cuticle pigmentation and that miR-33 mutants show a reduction in interfollicular stalk cells during oogenesis. Conclusion:Our data suggest that miR-33 is a conserved regulator of lipid homeostasis, and its targets are involved in both degradation and synthesis of fatty acids and TAG. The constellation of phenotypes involving tissues that are highly sensitive to metabolic state suggests that miR-33 serves to prevent extreme fluctuations in metabolically sensitive tissues.

Introduction: The runt-related transcription factor 3 (RUNX3) is a downstream effector of the transforming growth factor-β (TGF-β) signaling pathway, and has critical roles in apoptosis, angiogenesis, cell migration and invasion. Putative tumor suppressor activity of RUNX3 has been presented extensively in the literature, particularly in solid epithelial tumors and recently in lymphoma with loss of expression favoring tumorigenesis and/or prognosis, but its role in diffuse large B-cell lymphoma (DLBCL) has not been studied. Enhancer of zeste homolog-2 (EZH2), a histone methyltransferase, has been shown to mediate silencing of RUNX3. RUNX3 downregulation due to EZH2 upregulation has been shown in various solid tumors. In the present study, we investigated the EZH2 and RUNX3 RNA expression status in DLBCL and its impact on clinical outcome. Methods: A retrospective chart review was performed and 169 cases of DLBCL treated with chemoimmunotherapy between 2003 and 2013 were included. Immunodeficiency- or EBV-associated and MYC+ LBCL were excluded. Archived formalin-fixed-paraffin-embedded tissue samples were retrieved and RNA was extracted using commercially available kits. We correlated the RNA expression levels for EZH2 and RUNX3 in various sites using quantitative real-time PCR (Taqman assay) and custom designed primers for each gene. Control samples included three benign lymph nodes free of a neoplastic process. Results: We identified 66 cases of DLBCL, including25 nodal DLBCL and 41 extranodal DLBCL, with sufficient RNA extracted. Extranodal locations included testis (n=12), orbit (n=6), primary central nervous system (n=5), bone (n=3), breast (n=2) and viscera (n=13). The median age was 64 years (range 29- 81 years) with a female to male ratio of 0.4 (F=20 and M=46). Median overall survival (OS) was 28 months (1-156 months). Immunophenotypic subtype based on cell-of-origin using Hans algorithm was available in 63 cases; 34 cases were germinal center B-cell (GCB) type while 29 were non-GCB type. Treatment data was available in 63 cases and all patients received R-CHOP as initial therapy except three patients who died shortly after diagnosis. Forty-four cases showed higher expression of EZH2 and RUNX3 when compared to normal lymph nodes (p < 0.05). Nineteen out of 44 cases showed increased EZH2 and decreased RUNX3 expression (Group 1) while EZH2 expression was lower than RUNX3 in the remaining cases (Group 2). The remaining 22 DLBCL cases did not show significant correlation for expression (Group 3). Overall survival was significantly low in Group 1 compared to Group 2 and Group 3 (p =0.030 and p=0.026, respectively). There was no difference for OS between Groups 2 and 3 (p>0.05) (Figure 1). Conclusions: Our results showed that decreased RUNX3 RNA expression is associated with EZH2 overexpression and poses an adverse prognostic factor in DLBCL. Larger studies are needed to establish the prognostic and therapeutic utility of EZH2 and/or RUNX3. Disclosures Mehta: Pharmacyclics: Research Funding; Merck: Research Funding; Incyte: Research Funding; Medimmune: Research Funding; Roche Genentech: Research Funding; Bristol Myers Squibb: Research Funding; Seattle Genetics: Membership on an entity's Board of Directors or advisory committees. Forero:University of Alabama at Birmingham: Research Funding. Costa:Sanofi: Honoraria, Research Funding.