Farnesol-Induced Apoptosis in Human Lung Carcinoma Cells Is Coupled to the Endoplasmic

Farnesol-induced apoptosis in human lung carcinoma cells is coupled to the endoplasmic reticulum stress response.

Joo JH, Liao G, Collins JB, Grissom SF, Jetten AM.

Farnesol (FOH) and other isoprenoid alcohols induce apoptosis in various carcinoma cells and inhibit tumorigenesis in several in vivo models. However, the mechanisms by which they mediate their effects are not yet fully understood. In this study, we show that FOH is an effective inducer of apoptosis in several lung carcinoma cells, including H460. This induction is associated with activation of several caspases and cleavage of poly(ADP-ribose) polymerase (PARP). To obtain insight into the mechanism involved in FOH-induced apoptosis, we compared the gene expression profiles of FOH-treated and control H460 cells by microarray analysis. This analysis revealed that many genes implicated in endoplasmic reticulum (ER) stress signaling, including ATF3, DDIT3, HERPUD1, HSPA5, XBP1, PDIA4, and PHLDA1, were highly up-regulated within 4 h of FOH treatment, suggesting that FOH-induced apoptosis involves an ER stress response. This was supported by observations showing that treatment with FOH induces splicing of XBP1 mRNA and phosphorylation of eIF2alpha. FOH induces activation of several mitogen-activated protein kinase (MAPK) pathways, including p38, MAPK/extracellular signal-regulated kinase (ERK) kinase (MEK)-ERK, and c-jun NH(2)-terminal kinase (JNK). Inhibition of MEK1/2 by U0126 inhibited the induction of ER stress response genes. In addition, knockdown of the MEK1/2 and JNK1/2 expression by short interfering RNA (siRNA) effectively inhibited the cleavage of caspase-3 and PARP and apoptosis induced by FOH. However, only MEK1/2 siRNAs inhibited the induction of ER stress-related genes, XBP1 mRNA splicing, and eIF2alpha phosphorylation. Our results show that FOH-induced apoptosis is coupled to ER stress and that activation of MEK1/2 is an early upstream event in the FOH-induced ER stress signaling cascade. [Cancer Res 2007;67(16):7929-36].

Circulating insulin-like growth factor binding protein-1 and the risk of pancreatic cancer.

Wolpin BM, Michaud DS, Giovannucci EL, Schernhammer ES, Stampfer MJ, Manson JE, Cochrane BB, Rohan TE, Ma J, Pollak MN, Fuchs CS.

Department of Medical Oncology, Dana-Farber Cancer Institute.

Insulin-like growth factor (IGF)-I has growth-promoting effects on pancreatic cancer cells, and elevated fasting serum insulin has been linked to pancreatic cancer risk. IGF binding protein-1 (IGFBP-1) is a downstream target of insulin and inhibits IGF-I activity. To investigate whether prediagnostic plasma levels of IGFBP-1 are associated with pancreatic cancer risk, we did a prospective, case-control study nested within the Health Professionals Follow-up Study, the Nurses' Health Study, the Physicians' Health Study, and the Women's Health Initiative. We assayed circulating IGFBP-1 among 144 pancreatic cancer cases that occurred >/=4 years after plasma collection and in 429 controls, matched for date of birth, prospective cohort, smoking status, and fasting status. When compared with participants in the three highest quartiles of plasma IGFBP-1, those in the lowest quartile experienced a relative risk (RR) for pancreatic cancer of 2.07 [95% confidence intervals (95% CI), 1.26-3.39], after adjusting for other risk factors, including circulating IGF-I, IGF binding protein-3, and C-peptide. Only participants in the lowest quartile of plasma IGFBP-1 showed an elevated risk of pancreatic cancer. The influence of low plasma IGFBP-1 became progressively stronger with time; among cases diagnosed >/=8 years after blood collection, the adjusted RR was 3.47 (95% CI, 1.48-8.14), comparing the bottom versus the top three quartiles. The influence of plasma IGFBP-1 was most marked among participants who never smoked cigarettes (RR, 3.30; 95% CI, 1.48-7.35). Among participants in four U.S. prospective cohort studies, low plasma IGFBP-1 levels significantly predicted an increased risk of pancreatic cancer. [Cancer Res 2007;67(16):7923-8].

Platelet-Derived Growth Factor Receptor Regulates Myeloid and Monocytic Differentiation of HL-60 Cells.

Reiterer G, Yen A.

Department of Biomedical Sciences, Cornell University, Ithaca, New York.

Here, we show that the platelet-derived growth factor receptor (PDGFR) regulates myeloid and monocytic differentiation of HL-60 myeloblastic leukemia cells in response to retinoic acid (RA) and vitamin D3 (D3), respectively. Both RA and D3 decreased the expression of PDGFR-alpha and PDGFR-beta throughout differentiation. When cells were treated with the PDGFR inhibitor AG1296 in addition to RA or D3, signs of terminal differentiation such as inducible oxidative metabolism and cell substrate adhesion were enhanced. These changes were accompanied by an increased extracellular signal-regulated kinase 1/2 activation. AG1296 also resulted in elevated expression of differentiation markers CD11b and CD66c when administered with RA or D3. Interestingly, other markers did not follow the same pattern. Cells receiving AG1296 in addition to RA or D3 showed decreased G(1)-G(0) arrest and CD14, CD38, and CD89 expression. We thus provide evidence that certain sets of differentiation markers can be enhanced, whereas others can be inhibited by the PDGFR pathway. In addition, we found calcium levels to be decreased by RA and D3 but increased when AG1296 was given in addition to RA or D3, suggesting that calcium levels decrease during myeloid or monocytic differentiation, and elevated calcium levels can disturb the expression of certain differentiation markers. [Cancer Res 2007;67(16):7765-71].

Estrogen Receptor {alpha} Inhibits p53-Mediated Transcriptional Repression: Implications for the Regulation of Apoptosis.

Sayeed A, Konduri SD, Liu W, Bansal S, Li F, Das GM.

Department of Pharmacology and Therapeutics, Roswell Park Cancer Institute, Buffalo, New York.

Estrogen receptor alpha (ERalpha) and tumor suppressor protein p53 exert opposing effects on cellular proliferation. As a transcriptional regulator, p53 is capable of activating or repressing various target genes. We have previously reported that ERalpha binds directly to p53, leading to down-regulation of transcriptional activation by p53. In addition to transcriptional activation, transcriptional repression of a subset of target genes by p53 plays important roles in diverse biological processes, such as apoptosis. Here, we report that ERalpha inhibits p53-mediated transcriptional repression. Chromatin immunoprecipitation assays reveal that ERalpha interacts in vivo with p53 bound to promoters of Survivin and multidrug resistance gene 1, both targets for transcriptional repression by p53. ERalpha binding to p53 leads to inhibition of p53-mediated transcriptional regulation of these genes in human cancer cells. Transcriptional derepression of Survivin by ERalpha is dependent on the p53-binding site on the Survivin promoter, consistent with our observation that p53 is necessary for ERalpha to access the promoters. Importantly, mutagenic conversion of this site to an activation element enabled ERalpha to repress p53-mediated transcriptional activation. Further, RNA interference-mediated knockdown of ERalpha resulted in reduced Survivin expression and enhanced the propensity of MCF-7 cells to undergo apoptosis in response to staurosporine treatment, an effect that was blocked by exogenous expression of Survivin. These results unravel a novel mechanism by which ERalpha opposes p53-mediated apoptosis in breast cancer cells. The findings could have translational implications in developing new therapeutic and prevention strategies against breast cancer. [Cancer Res 2007;67(16):7746-55].

Retinoblastoma: from the two-hit hypothesis to targeted chemotherapy.

Macpherson D, Dyer MA.

Department of Embryology, Carnegie Institution, Baltimore, Maryland.

Studies on retinoblastoma have been at the heart of many of the landmark discoveries in cancer genetics over the past 35 years. However, these advances in the laboratory have had little effect on the treatment of children with retinoblastoma. One of the reasons for this has been the lack of preclinical models that recapitulated the genetic and histopathologic features of human retinoblastoma. In the past three years, a series of new animal models of retinoblastoma has been developed and characterized from several different laboratories using a variety of experimental approaches. It is encouraging that there is broad agreement about the consequences of inactivation of the Rb family in retinal development from these studies. More importantly, these new mouse models of retinoblastoma have contributed to clinical trials and novel therapeutic approaches for treating this debilitating childhood cancer. [Cancer Res 2007;67(16):7547-50].

Early developmental pathology due to cytochrome c oxidase deficiency is revealed by a new zebrafish model.

Baden KN, Murray J, Capaldi RA, Guillemin K.

Biology, Institute of Molecular Biology, University of Oregon, Eugene, OR 97403.

Deficiency of cytochrome c oxidase (COX) is associated with significant pathology in humans. However, the consequences for organogenesis and early development are not well understood. We have investigated these issues using a zebrafish model. COX deficiency was induced using morpholinos to reduce expression of CoxVa, a structural subunit, and Surf1, an assembly factor, both of which impaired COX assembly. Reduction of COX activity to 50% resulted in developmental defects in endodermal tissue, cardiac function, and swimming behavior. Cellular investigations revealed different underlying mechanisms. Apoptosis was dramatically increased in the hindbrain and neural tube and secondary motor neurons were absent or abnormal, explaining the motility defect. In contrast, the heart lacked apoptotic cells but showed increasingly poor performance over time, consistent with energy deficiency. The zebrafish model has revealed tissue-specific responses to COX deficiency and holds promise for discovery of new therapies to treat mitochondrial diseases in humans.

Induction of endogenous UCP3 suppresses mitochondrial oxidant emission during fatty-acid supported respiration.

Anderson EJ, Yamazaki H, Neufer PD.

Department of Exercise and Sport Science & Department of Physiology, East Carolina University, Greenville, NC 27858.

Uncoupling protein 3 (UCP3) expression increases dramatically in skeletal muscle under metabolic states associated with elevated lipid metabolism, yet the function of UCP3 in a physiological context remains controversial. Here, in situ mitochondrial H{sub}2O{sub}2 emission and respiration were measured in permeabilized fiber bundles prepared from both rat and mouse (wild-type) gastrocnemius muscle after a single bout of exercise plus 18h recovery (Ex/R) that induced a ~2- to 4-fold increase in UCP3 protein. Elevated uncoupling activity (i.e., GDP inhibitable) was evident in Ex/R fibers only upon addition of palmitate (known activator of UCP3) or under substrate conditions eliciting substantial rates of H{sub}2O{sub}2 production (i.e., respiration supported by succinate or palmitoyl-L-carnitine/malate, but not pyruvate/malate), indicative of UCP3 activation by endogenous ROS. In mice completely lacking UCP3 (ucp3 -/-), Ex/R failed to induce uncoupling activity. Surprisingly, when UCP3 activity was inhibited by GDP (rats) or in the absence of UCP3 (ucp3 -/-), H{sub}2O{sub}2 emission was significantly (P<0.05) higher in Ex/R versus non-exercised control fibers. Collectively, these findings demonstrate that the oxidant emitting potential of mitochondria is increased in skeletal muscle during recovery from exercise, possibly as a consequence of prolonged reliance on lipid metabolism and/or altered mitochondrial biochemistry/morphology, and that induction of UCP3 in vivo mediates an increase in uncoupling activity that restores mitochondrial H{sub}2O{sub}2 emission to non-exercised, control levels.

Lactogens promote beta cell survival through JAK2/STAT5 activation and BCL-XL upregulation.

Fujinaka Y, Takane K, Yamashita H, Vasavada RC.

Medicine, University of Pittsburgh, Pittsburgh, PA 15261.

One of the goals in the treatment for diabetes is to enhance pancreatic beta cell function, proliferation, and survival. This study explores the role of lactogenic hormones, prolactin (PRL) and placental lactogen (PL), in beta cell survival. We have previously shown that transgenic mice expressing mouse placental lactogen-1 (mPL1) in beta cells under the rat insulin II promoter (RIP) are resistant to the diabetogenic and cytotoxic effects of streptozotocin (STZ) in vivo. The current study demonstrates that lactogens protect rat insulinoma (INS-1) cells and primary mouse beta cells against two distinct beta cell death inducers, STZ and dexamethasone (DEX), in vitro. Further, we identify the mechanism through which lactogens protect beta cells against DEX-induced death. The signaling pathway mediating this protective effect is the janus-activated-kinase-2/ signal transducer and activator of transcription-5 (JAK2/STAT5) pathway. This is demonstrated in INS-1 cells and primary mouse beta cells using three separate approaches, pharmacological inhibitors, JAK2-specific siRNAs and a dominant-negative STAT5 mutant. Furthermore, lactogens specifically and significantly increase the anti-apoptotic protein Bcl-XL in insulinoma cells and mouse islets. Bcl-XL-specific siRNA significantly inhibits lactogen-mediated protection against DEX-induced beta cell death. We believe this is the first direct demonstration of lactogens mediating their protective effect through the JAK2/STAT5 pathway in the beta cell, and through Bcl-XL in any cell type.

A honey bee odorant receptor for the queen substance 9-oxo-2-decenoic acid.

Wanner KW, Nichols AS, Walden KK, Brockmann A, Luetje CW, Robertson HM.

Department of Entomology, University of Illinois at Urbana–Champaign, Urbana, IL 61801.

By using a functional genomics approach, we have identified a honey bee [Apis mellifera (Am)] odorant receptor (Or) for the queen substance 9-oxo-2-decenoic acid (9-ODA). Honey bees live in large eusocial colonies in which a single queen is responsible for reproduction, several thousand sterile female worker bees complete a myriad of tasks to maintain the colony, and several hundred male drones exist only to mate. The "queen substance" [also termed the queen retinue pheromone (QRP)] is an eight-component pheromone that maintains the queen's dominance in the colony. The main component, 9-ODA, acts as a releaser pheromone by attracting workers to the queen and as a primer pheromone by physiologically inhibiting worker ovary development; it also acts as a sex pheromone, attracting drones during mating flights. However, the extent to which social and sexual chemical messages are shared remains unresolved. By using a custom chemosensory-specific microarray and qPCR, we identified four candidate sex pheromone Ors (AmOr10, -11, -18, and -170) from the honey bee genome based on their biased expression in drone antennae. We assayed the pheromone responsiveness of these receptors by using Xenopus oocytes and electrophysiology. AmOr11 responded specifically to 9-ODA (EC50 = 280 +/- 31 nM) and not to any of the other seven QRP components, other social pheromones, or floral odors. We did not observe any responses of the other three Ors to any of the eight QRP pheromone components, suggesting 9-ODA is the only QRP component that also acts as a long-distance sex pheromone.

Apoptotic cells protect mice from autoimmune inflammation by the induction of regulatory B cells.

Gray M, Miles K, Salter D, Gray D, Savill J.

*Medical Research Council Centre for Inflammation Research, The Queen's Medical Research Institute, University of Edinburgh, 47 Little France Crescent, Edinburgh EH16 4TJ, United Kingdom.

The maintenance of immune tolerance to apoptotic cells (AC) within an inflammatory milieu is vital to prevent autoimmunity. To investigate this, we administered syngeneic AC i.v. into mice carrying a cohort of ovalbumin (OVA)-specific transgenic T cells (DO11.10) along with OVA peptide and complete Freund's adjuvant, observing a dramatic increase in OVA-specific IL-10 secretion. Activated splenic B cells responded directly to AC, increasing secretion of IL-10, and this programming by AC was key to inducing T cell-derived IL-10. We went on to ask whether AC are able to modulate the course of autoimmune-mediated, chronic inflammation. AC given up to 1 month before the clinical onset of collagen-induced arthritis protected mice from severe joint inflammation and bone destruction. Antigen-specific CD4(+) T cells again secreted significantly more IL-10, associated with a reduced titer of pathogenic anti-collagen II antibodies. Inhibition of IL-10 in vivo reversed the beneficial effects of AC. Passive transfer of B cells from AC-treated mice provided significant protection from arthritis. These data demonstrate that AC exert a profound influence on an adaptive immune response through the generation of CD19(+) regulatory B cells, which in turn are able to influence the cytokine profile of antigen-specific effector T cells.