A High-throughput Screening of a Chemical Compound Library in Ovarian Cancer Stem Cells

BACKGROUND

Epithelial ovarian cancer has a poor prognosis, mostly due to its late diagnosis and the development of drug resistance after a first platinum-based regimen. The presence of a specific population of "cancer stem cells" could be responsible of the relapse of the tumor and the development of resistance to therapy. For this reason, it would be important to specifically target this subpopulation of tumor cells in order to increase the response to therapy.

METHOD

We screened a chemical compound library assembled during the COST CM1106 action to search for compound classes active in targeting ovarian stem cells. We here report the results of the high-throughput screening assay in two ovarian cancer stem cells and the differentiated cells derived from them.

RESULTS AND CONCLUSION

Interestingly, there were compounds active only on stem cells, only on differentiated cells, and compounds active on both cell populations. Even if these data need to be validated in ad hoc dose response cytotoxic experiments, the ongoing analysis of the compound structures will open up to mechanistic drug studies to select compounds able to improve the prognosis of ovarian cancer patients.

Synthesis of protectin D1 analogs: novel pro-resolution and radiotracer agents

Protectin D1 is a specialized pro-resolving mediator with potent pro-resolving and anti-inflammatory effects in vivo in several human disease models. Herein the preparation of the first synthetic analog of protectin D1, named 22-F-PD1, is presented together with data from in vivo investigations. This analog showed potent pro-resolving and anti-inflammatory properties. These results inspired the preparation of the radiotracer 22-[18F]F-PD1-ME that was used in a positron emission tomography proof of concept study. Altogether, the findings presented contribute to new knowledge on the biomolecular properties of protectin D1 analogs. In addition, an improved formal synthesis of the metabolite 22-OH-PD1 is reported.

An original phylogenetic approach identified mitochondrial haplogroup T1a1 as inversely associated with breast cancer risk in BRCA2 mutation carriers

INTRODUCTION

Individuals carrying pathogenic mutations in the BRCA1 and BRCA2 genes have a high lifetime risk of breast cancer. BRCA1 and BRCA2 are involved in DNA double-strand break repair, DNA alterations that can be caused by exposure to reactive oxygen species, a main source of which are mitochondria. Mitochondrial genome variations affect electron transport chain efficiency and reactive oxygen species production. Individuals with different mitochondrial haplogroups differ in their metabolism and sensitivity to oxidative stress. Variability in mitochondrial genetic background can alter reactive oxygen species production, leading to cancer risk. In the present study, we tested the hypothesis that mitochondrial haplogroups modify breast cancer risk in BRCA1/2 mutation carriers.

METHODS

We genotyped 22,214 (11,421 affected, 10,793 unaffected) mutation carriers belonging to the Consortium of Investigators of Modifiers of BRCA1/2 for 129 mitochondrial polymorphisms using the iCOGS array. Haplogroup inference and association detection were performed using a phylogenetic approach. ALTree was applied to explore the reference mitochondrial evolutionary tree and detect subclades enriched in affected or unaffected individuals.

RESULTS

We discovered that subclade T1a1 was depleted in affected BRCA2 mutation carriers compared with the rest of clade T (hazard ratio (HR) = 0.55; 95% confidence interval (CI), 0.34 to 0.88; P = 0.01). Compared with the most frequent haplogroup in the general population (that is, H and T clades), the T1a1 haplogroup has a HR of 0.62 (95% CI, 0.40 to 0.95; P = 0.03). We also identified three potential susceptibility loci, including G13708A/rs28359178, which has demonstrated an inverse association with familial breast cancer risk.

CONCLUSIONS

This study illustrates how original approaches such as the phylogeny-based method we used can empower classical molecular epidemiological studies aimed at identifying association or risk modification effects.

Refined histopathological predictors of BRCA1 and BRCA2 mutation status: a large-scale analysis of breast cancer characteristics from the BCAC, CIMBA, and ENIGMA consortia

INTRODUCTION

The distribution of histopathological features of invasive breast tumors in BRCA1 or BRCA2 germline mutation carriers differs from that of individuals with no known mutation. Histopathological features thus have utility for mutation prediction, including statistical modeling to assess pathogenicity of BRCA1 or BRCA2 variants of uncertain clinical significance. We analyzed large pathology datasets accrued by the Consortium of Investigators of Modifiers of BRCA1/2 (CIMBA) and the Breast Cancer Association Consortium (BCAC) to reassess histopathological predictors of BRCA1 and BRCA2 mutation status, and provide robust likelihood ratio (LR) estimates for statistical modeling.

METHODS

Selection criteria for study/center inclusion were estrogen receptor (ER) status or grade data available for invasive breast cancer diagnosed younger than 70 years. The dataset included 4,477 BRCA1 mutation carriers, 2,565 BRCA2 mutation carriers, and 47,565 BCAC breast cancer cases. Country-stratified estimates of the likelihood of mutation status by histopathological markers were derived using a Mantel-Haenszel approach.

RESULTS

ER-positive phenotype negatively predicted BRCA1 mutation status, irrespective of grade (LRs from 0.08 to 0.90). ER-negative grade 3 histopathology was more predictive of positive BRCA1 mutation status in women 50 years or older (LR = 4.13 (3.70 to 4.62)) versus younger than 50 years (LR = 3.16 (2.96 to 3.37)). For BRCA2, ER-positive grade 3 phenotype modestly predicted positive mutation status irrespective of age (LR = 1.7-fold), whereas ER-negative grade 3 features modestly predicted positive mutation status at 50 years or older (LR = 1.54 (1.27 to 1.88)). Triple-negative tumor status was highly predictive of BRCA1 mutation status for women younger than 50 years (LR = 3.73 (3.43 to 4.05)) and 50 years or older (LR = 4.41 (3.86 to 5.04)), and modestly predictive of positive BRCA2 mutation status in women 50 years or older (LR = 1.79 (1.42 to 2.24)).

CONCLUSIONS

These results refine likelihood-ratio estimates for predicting BRCA1 and BRCA2 mutation status by using commonly measured histopathological features. Age at diagnosis is an important variable for most analyses, and grade is more informative than ER status for BRCA2 mutation carrier prediction. The estimates will improve BRCA1 and BRCA2 variant classification and inform patient mutation testing and clinical management.

Stereoselective synthesis of protectin D1: a potent anti-inflammatory and proresolving lipid mediator

A convergent stereoselective synthesis of the potent anti-inflammatory, proresolving and neuroprotective lipid mediator protectin D1 (2) has been achieved in 15% yield over eight steps. The key features were a stereocontrolled Evans-aldol reaction with Nagao's chiral auxiliary and a highly selective Lindlar reduction of internal alkyne 23, allowing the sensitive conjugated E,E,Z-triene to be introduced late in the preparation of 2. The UV and LC/MS-MS data of synthetic protectin D1 (2) matched those obtained from endogenously produced material.

COMPLEXO: identifying the missing heritability of breast cancer via next generation collaboration

Linkage analysis, positional cloning, candidate gene mutation scanning and genome-wide association study approaches have all contributed significantly to our understanding of the underlying genetic architecture of breast cancer. Taken together, these approaches have identified genetic variation that explains approximately 30% of the overall familial risk of breast cancer, implying that more, and likely rarer, genetic susceptibility alleles remain to be discovered.

Common variants at 12p11, 12q24, 9p21, 9q31.2 and in ZNF365 are associated with breast cancer risk for BRCA1 and/or BRCA2 mutation carriers

INTRODUCTION

Several common alleles have been shown to be associated with breast and/or ovarian cancer risk for BRCA1 and BRCA2 mutation carriers. Recent genome-wide association studies of breast cancer have identified eight additional breast cancer susceptibility loci: rs1011970 (9p21, CDKN2A/B), rs10995190 (ZNF365), rs704010 (ZMIZ1), rs2380205 (10p15), rs614367 (11q13), rs1292011 (12q24), rs10771399 (12p11 near PTHLH) and rs865686 (9q31.2).

METHODS

To evaluate whether these single nucleotide polymorphisms (SNPs) are associated with breast cancer risk for BRCA1 and BRCA2 carriers, we genotyped these SNPs in 12,599 BRCA1 and 7,132 BRCA2 mutation carriers and analysed the associations with breast cancer risk within a retrospective likelihood framework.

RESULTS

Only SNP rs10771399 near PTHLH was associated with breast cancer risk for BRCA1 mutation carriers (per-allele hazard ratio (HR) = 0.87, 95% CI: 0.81 to 0.94, P-trend = 3 × 10-4). The association was restricted to mutations proven or predicted to lead to absence of protein expression (HR = 0.82, 95% CI: 0.74 to 0.90, P-trend = 3.1 × 10-5, P-difference = 0.03). Four SNPs were associated with the risk of breast cancer for BRCA2 mutation carriers: rs10995190, P-trend = 0.015; rs1011970, P-trend = 0.048; rs865686, 2df-P = 0.007; rs1292011 2df-P = 0.03. rs10771399 (PTHLH) was predominantly associated with estrogen receptor (ER)-negative breast cancer for BRCA1 mutation carriers (HR = 0.81, 95% CI: 0.74 to 0.90, P-trend = 4 × 10-5) and there was marginal evidence of association with ER-negative breast cancer for BRCA2 mutation carriers (HR = 0.78, 95% CI: 0.62 to 1.00, P-trend = 0.049).

CONCLUSIONS

The present findings, in combination with previously identified modifiers of risk, will ultimately lead to more accurate risk prediction and an improved understanding of the disease etiology in BRCA1 and BRCA2 mutation carriers.

Interferon-γ inhibits ghrelin expression and secretion via a somatostatin-mediated mechanism

AIM: To investigate if and how the proinflammatory cytokine interferon γ (IFNγ) affects ghrelin expression in mice.

METHODS: The plasma concentration of ghrelin, and gastric ghrelin and somatostatin expression, were examined in wild-type mice and mice infected with Helicobacter pylori (H. pylori). Furthermore, ghrelin expression was examined in two achlorhydric mouse models with varying degrees of gastritis due to bacterial overgrowth. To study the effect of IFNγ alone, mice were given a subcutaneous infusion of IFNγ for 7 d. Finally, the influence of IFNγ and somatostatin on the ghrelin promoter was characterized.

RESULTS: H. pylori infection was associated with a 50% reduction in ghrelin expression and plasma concentration. Suppression of ghrelin expression was inversely correlated with gastric inflammation in achlorhdyric mouse models. Subcutaneous infusion of IFNγ suppressed fundic ghrelin mRNA expression and plasma ghrelin concentrations. Finally, we showed that the ghrelin promoter operates under the control of somatostatin but not under that of IFNγ.

CONCLUSION: Gastric infection and inflammation is associated with increased IFNγ expression and reduced ghrelin expression. IFNγ does not directly control ghrelin expression but inhibits it indirectly via somatostatin.

Regulation of neuronal cholecystokinin gene transcription

Cholecystokinin (CCK) is a neuroendocrine peptide expressed in I-cells of the small intestine and in central and peripheral neurons. Whereas intestinal CCK is involved in the release of pancreatic enzymes and the contraction of the gallbladder, cerebral CCK is implicated in a variety of functions, such as feeding behaviour, anxiety and memory. The expression of CCK is developmentally regulated. Brain CCK mRNA levels are low before birth, but increase markedly shortly after birth and reach adult like patterns of expression three weeks after birth during the final maturation of the central nervous system. In the adult, several substances induce neuronal CCK mRNA expression via activation of transcription factors binding to regulatory elements in the CCK promoter. Recent studies have examined the signaling pathways, transcription factors and regulatory elements involved in cAMP, fibroblast growth factor-2, and calcium-induced CCK gene transcription in neuronal cells. The review describes the signaling pathways and transcription factors involved in neuronal CCK gene transcription.

Regulation of neuronal cholecystokinin gene transcription

Cholecystokinin (CCK) is a neuroendocrine peptide expressed in I-cells of the small intestine and in central and peripheral neurons. Whereas intestinal CCK is involved in the release of pancreatic enzymes and the contraction of the gallbladder, cerebral CCK is implicated in a variety of functions, such as feeding behaviour, anxiety and memory. The expression of CCK is developmentally regulated. Brain CCK mRNA levels are low before birth, but increase markedly shortly after birth and reach adult like patterns of expression three weeks after birth during the final maturation of the central nervous system. In the adult, several substances induce neuronal CCK mRNA expression via activation of transcription factors binding to regulatory elements in the CCK promoter. Recent studies have examined the signaling pathways, transcription factors and regulatory elements involved in cAMP, fibroblast growth factor-2, and calcium-induced CCK gene transcription in neuronal cells. The review describes the signaling pathways and transcription factors involved in neuronal CCK gene transcription.

Cholecystokinin gene transcription: promoter elements, transcription factors and signaling pathways

Cholecystokinin (CCK) is a neuropeptide expressed in the small intestine and in the central and peripheral nervous system. CCK gene expression is both spatially and temporally regulated. In neurons CCK production is increased by growth factors, cyclic adenosine 3', 5'-monophosphate (cAMP), dopamine, estrogen, and injury situations, while intestinal CCK expression is mainly regulated by food intake. The function of the proximal CCK promoter has been examined by transfection of human CCK-CAT reporter constructs in cultured cells, DNase I footprinting and gel shift assays. These studies have led to the identification of regulatory elements and transcription factors important for basal and stimulated gene expression and depicted the signaling pathways involved in growth factor and cAMP induced CCK transcription. The review outlines the current knowledge of the regulation of CCK transcription and describes the role of putative transcription factors in tissue-specific CCK gene expression.

Function of the C-36 to T polymorphism in the human cholecystokinin gene promoter

Cholecystokinin (CCK) is the most abundant neuropeptide in the mammalian brain, and in man significant quantities are expressed in all regions of the brain.1,2 Therefore, CCK has been implicated in a variety of CNS functions-such as feeding behavior, anxiety, analgesia and memory functions as well as psychiatric disease like panic disorder and schizophrenia (for review, see2,3). Recently, a number of studies have indicated that a C-36 to T transition in the CCK gene promoter Sp1 element4 (Figure 1) is associated with alcoholism and withdrawal symptoms as well as panic disorder.5-7 Moreover, it has been proposed that the polymorphism plays a direct role in the pathogenesis of the disorders by decreasing the expression and synthesis of CCK peptides. The significance of these findings is still unclear and other studies have failed to demonstrate linkage between the polymorphism and alcoholism.8 In this study we examined the function of the C-36 to T transition in transcription of the human CCK gene. We demonstrate that substitution of the C-36 residue causes a slight reduction of Sp1 and Sp3 binding, but this has no effect on transcription in vivo. Moreover, no difference in the response to physiological stimuli was observed. Taken together the results show that the C to T polymorphism does not play a direct role in the pathogenesis of either alcoholism or panic disorder and that a putative association to these disorders is likely to be the result of co-segregation with a linked mutation.

Negative cooperativity between juxtaposed E-box and cAMP/TPA responsive elements in the cholecystokinin gene promoter

The promoter of the cholecystokinin (CCK) gene possesses evolutionary conserved juxtaposed E-box and cAMP/TPA responsive elements (CRE/TRE). We have examined the functional interaction of these two sites. As previously noted, c-Jun/c-Fos heterodimers greatly increase promoter activity through association with the CRE/TRE. Mutation of the E-box enhanced the activation by c-Jun/c-Fos, as well as stimulation by forskolin and bFGF, that acts through the CRE/TRE site. Moreover, c-Jun/c-Fos stimulation was inhibited by co-expression of c-Myc and Max. The results indicate that factors associating with the E-box exhibit a negative cooperative effect on the activation via the CRE/TRE element. We propose that this mechanism plays a significant role in CCK gene transcription and other genes with juxtaposed E-box and CRE/TRE.

Mitogen-activated protein kinase and protein kinase A signaling pathways stimulate cholecystokinin transcription via activation of cyclic adenosine 3',5'-monophosphate response element-binding protein

Cholecystokinin (CCK) is a potent neuropeptide expressed in the small intestine and in the central nervous system. We have examined the effect of basic fibroblast factor (bFGF) and forskolin on CCK gene transcription and depicted the signaling pathways that lead to promoter activation. bFGF and forskolin stimulated promoter activity via a cAMP response element (CRE)/12-O-tetradecanoylphorbol-13-acetate response element (TRE) located 80 bp upstream from the transcription initiation site. In nuclear extracts from unstimulated as well as stimulated cells, only CRE-binding protein (CREB) and activating transcription factor-1 (ATF-1) bound to the CRE/TRE, and activation was associated with phosphorylation of CREB serine-133 and ATF-1 serine-63. In murine F9 cells, CREB stimulated promoter activity 10-fold in the presence of protein kinase A (PKA), and in SK-N-MC cells activation was inhibited 60-70% by a dominant negative CREB mutant. In contrast, ATF-1 had no effect in F9 cells and exhibited a dominant negative effect in SK-N-MC cells. bFGF stimulation led to phosphorylation of the p38 mitogen-activated protein kinase (MAPK), and the extracellular signal-regulated kinase (ERK) MAPK and promoter activation, phosphorylation of CREB, and GAL4-CREB-dependent transcription were selectively prevented by a dominant negative Ras-mutant, the p38 MAPK-specific inhibitor SB203580, and the MAP/ERK kinase 1 (MEK1) inhibitor PD098059. Forskolin stimulation proceeded via the PKA pathway, and to a minor extent via the p38 and ERK MAPK pathways. We conclude that bFGF and forskolin stimulate the CCK gene promoter via the CRE/TRE(-80) in the proximal promoter region. Signaling proceeds through the p38 MAPK, the ERK MAPK, and the PKA-signaling pathways, which leads to cumulative phosphorylation and activation of CREB. We propose that bFGF in combination with neurotransmitters/neuropeptides coupling to the PKA-signaling pathway play an important role in the control of CCK gene expression.

Transcriptional regulation of the human cholecystokinin gene: composite action of upstream stimulatory factor, Sp1, and members of the CREB/ATF-AP-1 family of transcription factors

We have examined cis-elements and trans-acting factors that regulate transcription of the human cholecystokinin (CCK) gene. Transient expression of CCK promoter deletion constructs in human SK-N-MC neuroblastoma cells depicted positive cis-elements between the positions -100 to -92, -84 to -74, and -58 to -37, 5' to the transcription initiation site. Correspondingly, DNase I protection analysis showed that transacting factors bound to elements within these regions. The sequences encompass a putative basic helix-loop-helix leucine zipper (bHLH-ZIP) element, an Sp1 element, and a combined cAMP- and TPA-responsive element (CRE/TRE) at positions -97 to -92, -39 to -34, and -80 to -73, respectively. Mobility and supershift assays demonstrated that upstream stimulatory factor (USF) and Sp1 bind to the former elements and competition experiments confirmed that CREB/ATF and AP-1 bind to the CRE/TRE element. Mutation of the bHLH-ZIP and CRE/TRE elements decreased the activity of the promoter by 65% and 42%, respectively. The activity of the promoter was increased six- and two-fold after stimulation with forskolin and TPA, respectively. Stimulation was eliminated after mutation of the CRE/TRE element. Co-transfection experiments with pRSV-c-jun, pSV-fos, and pRC-RSV-CREB constructs showed that jun, CREB, and AP-1 stimulate transcription. We conclude that USF, Sp1, and members of the CREB/ATF and AP-1 family of transcription factors are the major determinants of CCK gene transcription.

Homochiral glycerol derivatives by lipase-catalysed racemate resolution

Various aspects of enzyme-catalysed racemate resolution are discussed by using examples from hydrolysis of butanoates of glycerol derivatives. Primary esters of various 1,2-ketals gave low enantioselectivity (E). The results with secondary esters varied. The highest E value (> 100) was obtained when the primary ether groups were methyl and phenylethyl. For the corresponding methyl, phenyl diether E was observed to increase as the hydrolysis proceeded. The stereochemistry of the products agree with a proposed model for lipases.

The effect of chelating agents on vanadium distribution in the rat body and on uptake by human erythrocytes

Pentavalent vanadium (V5) as Na48VO3 was given i.p. to male Wistar rats at a dose of 5 mumol/kg in order to study its organ distribution pattern. Two days after injection, kidneys reached a V level of about 28 nmol/g wet weight, followed in decreasing order by spleen, liver, bone, blood plasma, testis, lung, erythrocytes and brain in control rats. A similar distribution pattern was seen after injection of tetravalent vanadium (V4) given as 48VOSO4. Two chelators, desferrioxamine B (Desferal) or Ca-Na3-diethylene triamine pentaacetic acid (DTPA), were given i.p. 24 h after the vanadium injections to different groups of rats at two dosage levels, 30 and 100 mumol/kg. Desferal (30 mumol/kg) reduced the vanadium content of the kidney by 17%, of the liver by 0%, and of the lung by 7%. The corresponding figures for the effect of DTPA (30 mumol/kg) were 7%, plus 15%, and 0%, respectively. At 100 mumol/kg, Desferal reduced the same organ levels by 20%, 26%, and 25%, respectively, and DTPA by 9%, 18%, and 25%, respectively. Both chelators raised faecal excretion at the low level, and both urinary and faecal excretion at the high level. Spleen and bone seemed to bind vanadium to a higher degree than the other organs under examination. Human erythrocytes, when incubated with 48VOSO4 (V4) or Na48VO3 (V5), were found to accumulate nearly the double amount of V5 as compared to V4. Glutathione (GSH) which is the main reducing substance within the erythrocytes, reduced the uptake of V5 to the V4 level when incubated together with GSH before addition to the cell suspension. Pretreating the erythrocytes with diethyl-maleate (DEM) which blocks the reducing SH groups of intracellular GSH, also reduced the uptake of V5. This may indicate a GSH dependent reduction of V5 to V4 within the erythrocytes. Four chelators, among them Desferal and DTPA, were found to reduce the cellbound amount of vanadium, either by extracting vanadium as V4, or by inhibiting uptake by the red blood cells.