Expression of mutant proteins or viral infection mayinterfere with proper protein folding activity in the endoplasmic reticulum (ER). Several pathways that maintain cellular homeostasis were activated in response to these ER disturbances. Here we investigated which of these ER stress-activated pathways induce COX-2 and potentially oncogenesis. Tunicamycin and brefeldin A, two ER stress inducers, increased the expression of COX-2 in ML-1 or MCF-7 cells. Nuclear translocation of NF-B and activation of pp38 MAPK were observed during ER stress. I B␣ kinase inhibitor Bay 11-7082 or I B␣ kinase dominant negative mutant significantly inhibited the induction of COX-2. pp38 MAPK inhibitor SB203580 or eIF2␣ phosphorylation inhibitor 2-aminopurine attenuated the nuclear NF-B DNA binding activity and COX-2 induction. Expression of mutant hepatitis B virus (HBV) large surface proteins, inducers of ER stress, enhanced the expression of COX-2 in ML-1 and HuH-7 cells. Transgenic mice showed higher expression of COX-2 protein in liver and kidney tissue expressing mutant HBV large surface protein in vivo. Similarly, increased expression of COX-2 mRNA was observed in human hepatocellular carcinoma tissue expressing mutant HBV large surface proteins. In ML-1 cells expressing mutant HBV large surface protein, anchorage-independent growth was enhanced, and the enhancement was abolished by the addition of specific COX-2 inhibitors. Thus, ER stress due either to expression of viral surface proteins or drugs can stimulate the expression of COX-2 through the NF-B and pp38 kinase pathways. Our results provide important insights into cellular carcinogenesis associated with latent endoplasmic reticulum stress.

Meroterpenoids are a class of fungal natural products that are produced from polyketide and terpenoid precursors. An understanding of meroterpenoid biosynthesis at the genetic level should facilitate engineering of second-generation molecules and increasing production of first-generation compounds. The filamentous fungus Aspergillus nidulans has previously been found to produce two meroterpenoids, austinol and dehydroaustinol. Using targeted deletions that we created, we have determined that, surprisingly, two separate gene clusters are required for meroterpenoid biosynthesis. One is a cluster of four genes including a polyketide synthase gene, ausA. The second is a cluster of ten additional genes including a prenyltransferase gene, ausN, located on a separate chromosome. Chemical analysis of mutant extracts enabled us to isolate 3,5-dimethylorsellinic acid and ten additional meroterpenoids that are either intermediates or shunt products from the biosynthetic pathway. Six of them were identified as novel meroterpenoids in this study. Our data, in aggregate, allow us to propose a complete biosynthetic pathway for the A. nidulans meroterpenoids.

Xanthones are a class of molecules that bind to a number of drug targets and possess a myriad of biological properties. An understanding of xanthone biosynthesis at the genetic level should facilitate engineering of second-generation molecules and increasing production of first-generation compounds. The filamentous fungus Aspergillus nidulans has been found to produce two prenylated xanthones, shamixanthone and emericellin, and we report the discovery of two more, variecoxanthone A and epishamixanthone. Using targeted deletions that we created, we determined that a cluster of 10 genes including a polyketide synthase gene, mdpG, is required for prenyl xanthone biosynthesis. mdpG was shown to be required for the synthesis of the anthraquinone emodin, monodictyphenone, and related compounds, and our data indicate that emodin and monodictyphenone are precursors of prenyl xanthones. Isolation of intermediate compounds from the deletion strains provided valuable clues as to the biosynthetic pathway, but no genes accounting for the prenylations were located within the cluster. To find the genes responsible for prenylation, we identified and deleted seven putative prenyltransferases in the A. nidulans genome. We found that two prenyltransferase genes, distant from the cluster, were necessary for prenyl xanthone synthesis. These genes belong to the fungal indole prenyltransferase family that had previously been shown to be responsible for the prenylation of amino acid derivatives. In addition, another prenyl xanthone biosynthesis gene is proximal to one of the prenyltransferase genes. Our data, in aggregate, allow us to propose a complete biosynthetic pathway for the A. nidulans xanthones.

This study was aimed at elucidating the mechanism by which FTY720, a synthetic sphingosine immunosuppressant, mediated antitumor effects in hepatocellular carcinoma (HCC) cells. The three HCC cell lines examined, Hep3B, Huh7, and PLC5, exhibited differential susceptibility to FTY720-mediated suppression of cell viability, with IC 50 values of 4.5, 6.3, and 11 Mmol/L, respectively. Although FTY720 altered the phosphorylation state of protein kinase B and p38, our data refuted the role of these two signaling kinases in FTY720-mediated apoptosis. Evidence indicates that the antitumor effect of FTY720 was attributable to its ability to stimulate reactive oxygen species (ROS) production, which culminated in protein kinase C (PKC)D activation and subsequent caspase-3-dependent apoptosis. We showed that FTY720 activated PKCD through two distinct mechanisms: phosphorylation and caspase-3-dependent cleavage. Cotreatment with the caspase-3 inhibitor Z-VAD-FMK abrogated the effect of FTY720 on facilitating PKCD proteolysis. Equally important, pharmacologic inhibition or shRNA-mediated knockdown of PKCD protected FTY720-treated Huh7 cells from caspase-3 activation. Moreover, FTY720 induced ROS production to different extents among the three cell lines, in the order of Hep3B > Huh7 >> PLC5, which inversely correlated with the respective glutathione S-transferase P expression levels. The low level of ROS generation might underlie the resistant phenotype of PLC5 cells to the apoptotic effects of FTY720. Blockade of ROS production by an NADPH oxidase inhibitor protected Huh7 cells from FTY720-induced PKCD activation and caspase-3-dependent apoptosis. Together, this study provides a rationale to use FTY720 as a scaffold to develop potent PKCD-activating agents for HCC therapy.

BackgroundPolycystic ovary syndrome (PCOS) is one of the most common endocrine disorders among women of reproductive age. A higher prevalence of psychiatric comorbidities, including depressive disorder, anxiety disorder, and bipolar disorder has been proved in patients with PCOS. However, a clear temporal causal relationship between PCOS and psychiatric disorders has not been well established.ObjectiveWe explored the relationship between PCOS and the subsequent development of psychiatric disorders including schizophrenia, bipolar disorder, depressive disorder, anxiety disorder, and sleep disorder.MethodsWe identified patients who were diagnosed with PCOS by an obstetrician-gynecologist in the Taiwan National Health Insurance Research Database. A comparison cohort was constructed of patients without PCOS who were matched according to age and sex. The occurrence of subsequent new-onset psychiatric disorders was evaluated in both cohorts based on diagnoses made by psychiatrists.ResultsThe PCOS cohort consisted of 5431 patients, and the comparison cohort consisted of 21,724 matched control patients without PCOS. The incidence of depressive disorder (hazard ratio [HR] 1.296, 95% confidence interval [CI] 1.084–.550), anxiety disorder (HR 1.392, 95% CI 1.121–1.729), and sleep disorder (HR 1.495, 95% CI 1.176–1.899) were higher among the PCOS patients than among the patients in the comparison cohort. In addition, a higher incidence of newly diagnosed depressive disorder, anxiety disorder, and sleep disorder remained significantly increased in all of the stratified follow-up durations (0–1, 1–5, ≥5 y).ConclusionsPCOS might increase the risk of subsequent newly diagnosed depressive disorder, anxiety disorder, and sleep disorder. The risk of newly diagnosed bipolar disorder, which has often been reported in the literature to be comorbid with PCOS, was not significantly elevated.