Search

Background: High-grade serous ovarian cancer (HGSOC) is the most lethal subtype of ovarian cancer due to the high rate of early relapse and resistance to chemotherapy. MicroRNAs (miRNAs) control the post-transcriptional expression of a substantial number of coding genes related to ovarian cancer. Therefore, a great interest in the discovery of miRNA-based therapeutics drives many researchers in the field. To identify relevant targets for miRNA-based therapeutics, in this study we analyzed the miRNA targetome associated with early relapse in HGSOC.Methods: Four Gene Expression Omnibus (GEO) datasets were analyzed by GEO2R to find differentially expressed miRNAs (DEMs) in early relapse patients. The miRDB tool was used to predict the gene targets of the DEMs. Functional annotation and cluster analysis was performed on Database for Visualization and Integrated Discovery and Metascape to identify biological processes enriched in the miRNA targetome. To verify the prognostic role of the key miRNA targets, Kaplan-Meier survival analysis was conducted in a validation dataset curated from The Cancer Genome Atlas and GEO datasets on KM-Plotter. A protein-protein interaction network of the prognostic miRNA targets was constructed on STRING. Network analysis was performed on Cytoscape to find the genes with the highest degree and centrality. The interactors and pathways associated with the key miRNA-target genes were searched on inBio Discover.Results: We identified a wide miRNA targetome with fifteen common miRNA targets associated with early relapse in HGSOC. These miRNA targets were enriched in biological processes associated with “transcription from RNA polymerase II promoter”. Further analysis on the validation set verified the prognostic role of thirteen of these targets in HGSOC. The network analysis revealed CWC27, DCUN1D1, MEF2C, and SPOPL as the central miRNA targets associated with early relapse. The primary interactor hubs of these four genes were involved in processes that regulate the synthesis or cleavage of other gene products, further expanding the scope of impact of the miRNA targetome.Conclusions: We believe that the four miRNA targets we identified in this study may be potential targets of miRNA-based therapeutics to prevent early relapse in HGSOC.

Hypoxia is the principal architect of the topographic heterogeneity in tumors. Hypoxia-inducible factor-1α (HIF-1α) reinforces all hallmarks of cancer and donates cancer cells with more aggressive characteristics at hypoxic niches. HIF-1α potently induces sustained growth factor signaling, angiogenesis, epithelial–mesenchymal transition, and replicative immortality. Hypoxia leads to the selection of cancer cells that evade growth suppressors or apoptotic triggers and deregulates cellular energetics. HIF-1α is also associated with genetic instability, tumor-promoting inflammation, and escape from immunity. Therefore, HIF-1α may be an important therapeutic target in cancer. Despite that, the drug market lacks safe and efficacious anti-HIF-1α molecules, raising the quest for fully unveiling the complex interactome of HIF-1α in cancer to discover more effective strategies. The knowledge gap is even wider in gastric cancer, where the number of studies on hypoxia is relatively low compared to other well-dissected cancers. A comprehensive review of the molecular mechanisms by which HIF-1α induces gastric cancer hallmarks could provide a broad perspective to the investigators and reveal missing links to explore in future studies. Thus, here we review the impact of HIF-1α on the cancer hallmarks with a specific focus on gastric cancer.

[Image: see text] A red-absorbing, water-soluble, and iodinated resorufin derivative (R1) that can be selectively activated with a monoamine oxidase (MAO) enzyme was synthesized, and its potential as a photodynamic therapy (PDT) agent was evaluated. R1 showed high (1)O(2) generation yields in aqueous solutions upon addition of MAO isoforms, and it was further tested in cell culture studies. R1 induced photocytotoxicity after being triggered by endogenous MAO enzyme in cancer cells with a much higher efficiency in SH-SY5Y neuroblastoma cells with high MAO-A expression. Additionally, R1 displayed differential cytotoxicity between cancer and normal cells, without any considerable dark toxicity. To the best of our knowledge, R1 marks the first example of a resorufin-based photosensitizer (PS) as well as the first anticancer drug that is activated by a MAO enzyme. Remarkably, the target PDT agent was obtained only in three steps as a result of versatile resorufin chemistry.

Gastric cancer (GC) is the fifth most common cancer and the fourth leading cause of deaths from cancer. Although the combination of conventional chemotherapeutics with molecular targeted agents targeting tumor-specific biomarkers has increased the treatment efficacy in certain types of cancer such as breast cancer, similar success could not be achieved in GC treatment. Therefore, there is an urgent need for combination protocols that can increase the therapeutic success in GC therapy. Synergism is the most important requirement for the success of drug combinations in cancer therapy. Besides the choice of anti-cancer agents included in combination protocols, the order of application and the time interval between drug applications, are important determinants of synergism. In this study, we aim to test whether sequential application of conventional chemotherapeutic-molecular targeted agent pairs can transform antagonistic response into synergistic response in GC. To achieve the goals of this study, we have screened dual combinations of five different chemotherapeutics from anthracyclins, platinium derivatives, taxanes, fluoropyrimidines and topoisomerase inhibitors, and three different molecular-targeted agents targeting EGFR, mTOR or c-Met in four different GC cell models to identify synergistic and antagonistic drug pairs. The most antagonistic drug pairs are selected to test whether sequential application schedules can transform antagonism into synergism for these drug pairs. Drug pairs that display strongest synergism in concomitant applications are also further analyzed in detail to investigate their potential in GC treatment. The degree of synergism is measured with Chou-Talalay Method, and apoptosis, autophagy and cell cycle responses were investigated to identify possible molecular mechanisms of synergism. Our data shows that sequential application schedules can transform antagonism into synergism. We believe that the treatment schedules that will be defined in this study can increase the success of chemotherapeutic-molecular targeted agent combinations in GC. Citation Format: Ozen Leylek, Gulnihal Ozcan. Achieving synergism in combination chemotherapy for gastric cancer treatment [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2021 Oct 7-10. Philadelphia (PA): AACR; Mol Cancer Ther 2021;20(12 Suppl):Abstract nr P023.

The discovery of RNA interference, first in plants and Caenorhabditis elegans and later in mammalian cells, led to the emergence of a transformative view in biomedical research. Knowledge of the multiple actions of non-coding RNAs has truly allowed viewing DNA, RNA and proteins in novel ways. Small interfering RNAs (siRNAs) can be used as tools to study single gene function both in vitro and in vivo and are an attractive new class of therapeutics, especially against undruggable targets for the treatment of cancer and other diseases. Despite the potential of siRNAs in cancer therapy, many challenges remain, including rapid degradation, poor cellular uptake and off-target effects. Rational design strategies, selection algorithms, chemical modifications and nanocarriers offer significant opportunities to overcome these challenges. Here, we review the development of siRNAs as therapeutic agents from early design to clinical trial, with special emphasis on the development of EphA2-targeting siRNAs for ovarian cancer treatment.

Introduction In Turkey, pharmacovigilance began in 1985. A fully structured adverse drug reaction (ADR)-reporting system was established with the publication of the first pharmacovigilance regulation in 2005. Subsequent regulation published in 2014 brought further improvements to the system. Objective In this study, we aimed to analyse the ADR-reporting pattern in the context of the first pharmacovigilance legislation in Turkey. Methods We analysed ADR reports submitted to the Turkish Pharmacovigilance Center (TUFAM) from 2005 to 2014 with respect to reporting rate (RR), patient characteristics, type of the ADRs, suspected drugs, source of the report and the profession of the reporter. Results The annual RR increased gradually over the study period. RRs for females were greater than those for males. RRs were highly correlated with age. Most commonly reported ADRs were skin and subcutaneous tissue disorders. Most commonly suspected drugs were antineoplastic and immunomodulating agents. There was no remarkable change in reporting pattern of ADRs, patient characteristics or classes of suspected drugs over the years. The most common source of reports was spontaneous reporting. Contribution of the reports from studies increased gradually. Most of the reports were reported by physicians. RRs by pharmacists increased substantially over the years. Conclusion This study showed that the annual RR increased gradually over the 9-year study period. This increase was neither due to an increased reporting of a specific group of ADRs or drugs, nor to an increased reporting in a specific group of patients. There was a general increase in RR in parallel to pharmacovigilance activities. Electronic supplementary material The online version of this article (doi:10.1007/s40801-015-0054-1) contains supplementary material, which is available to authorized users.

The modulation of cardiac functions by nitric oxide (NO) was established. This study examined the influences of phosphodiesterase (PDE) inhibitors on the action of NO in the different regions of the rat heart. NO donor diethylamine nonoate (DEA/NO) (0.1-100 μM) decreased functions of the right atrium. DEA/NO-induced depression of the developed tension of the right atrium was inhibited by [erythro-9-(2-hydroxy-3-nonyl)adenine] (PDE2 inhibitor), augmented by milrinone (PDE3 inhibitor), and upturned by rolipram (PDE4 inhibitor). A DEA/NO-induced decrease in the resting tension was inhibited by vinpocetine (PDE1 inhibitor) and [erythro-9-(2-hydroxy-3-nonyl)adenine] but reversed by rolipram. The decreased sinus rate by DEA/NO was prevented by vinpocetine and rolipram. DEA/NO increased cyclic guanosine monophosphate and cyclic adenosine monophosphate (cAMP) concentrations in the right atrium, and rolipram enhanced increased cAMP level. DEA/NO had no effect on the contraction of the papillary muscle. However, unchanged contraction under DEA/NO stimulation was decreased by vinpocetine, milrinone, and rolipram. DEA/NO increased cyclic guanosine monophosphate concentration but has no effect on cAMP in the papillary muscle. However, in the presence of vinpocetine and milrinone, DEA/NO reduced cAMP level. The PDE5 inhibitor sildenafil has no effect on DEA/NO actions. This study indicates that a variety of PDE activities in different regions of the rat heart shapes the action of NO on the myocardium.

Activation of β(2)-adrenegic receptor (β(2)-AR) leads to an increase in intracellular cAMP and activation of ERK. These two signals are activated by the interaction of the receptor with different transducer partners. We showed that the intrinsic activities of β(2)-AR ligands for stimulating cAMP production and ERK phosphorylation responses in HEK-293 cells were not correlated. The lack of correlation resulted mainly from the discrepancy between the intrinsic activities of two groups of ligands for these two responses: The first group consisted of clenbuterol, cimaterol, procaterol, and terbutaline which acted as full agonists for cAMP production but displayed very weak effect on ERK phosphorylation. The second group comprised adrenaline and noradrenaline which displayed higher intrinsic activity for the ERK phosphorylation than for the cAMP response. Thus, both groups behaved as functionally selective ligands. The functional selectivity of the first group was observable only in adherent cells when confluence was approximately 100%. When cell-cell contact was minimized either by decreasing the density of the adherent cells or by bringing the cells into suspension, the first group of ligands gained the ability to stimulate ERK phosphorylation without a change in their effect on cAMP production. In contrast, selectivity of the second group was independent of the adherence state of the cells. Our results show that the inherent "bias" of ligands in coupling a G protein-coupled receptor to different transducers may not always be revealed as functional selectivity when there is a "cross-talk" between the signaling pathways activated by the same receptor.

Membrane rafts and caveolae are specialized microdomains of the cell membrane that form physical platforms for compartmentalization of signalling molecules. Here, we intended to gain insight into the consequences of caveolar localization in G protein-coupled receptor function. We analysed beta(2)-adrenoceptor signalling in purified CRLDF (caveolin-rich low density fractions) of beta(2)-adrenoceptor-overexpressing HEK-293 cells. beta(2)-adrenoceptor and Gs immunoreactivities and forskolin-stimulated adenylate cyclase activity were all detected in CRLDF obtained by the conventional raft purification method that uses Triton X-100 solubilization. However, Triton X-100 caused a complete loss of the functional coupling between beta(2)-adrenoceptor, Gs and adenylate cyclase. Therefore, we developed an optimized purification method based on n-octyl-beta-d-glucopyranoside solubilization, where the functional properties of beta(2)-adrenoceptor, Gs and adenylate cyclase were preserved in the CRLDF. Using this method, we showed that isoproterenol-stimulated adenylate cyclase activity was similar in CRLDF and bulk membrane preparations of HEK-293 cells that overexpress beta(2)-adrenoceptor or beta(2)-adrenoceptor-Gs fusion. Accordingly, treatment of cells with methyl-beta-cyclodextrin, a caveola-disrupting agent, did not affect beta(2)-adrenoceptor-induced cAMP response. Likewise, these responses were insensitive to caveolin 1 and 2 overexpression. On the other hand, methyl-beta-cyclodextrin treatment did decrease beta(2)-adrenoceptor-induced ERK phosphorylation. However, the latter effect of methyl-beta-cyclodextrin could be attributed to a non-specific effect rather than its ability to disrupt membrane microdomains. We showed that localization in the raft microdomains did not affect the signalling efficiency of beta(2)-adrenoceptor-Gs-adenylate cyclase pathway, and that methyl-beta-cyclodextrin may inhibit signalling by directly affecting the signalling system independently of its caveola-disrupting property.