Glycoprotein-glycoprotein receptor binding detection using bioluminescence resonance energy transfer

The glycoprotein receptors, members of the large G protein-coupled receptors (GPCRs) family, are characterized by a large extracellular domains responsible of binding their glycoprotein hormones. Hormone-receptor interactions are traditionally analyzed by ligand-binding assays most often using radiolabeling but also by thermal shift assays. Despite their high sensitivity, these assays require appropriate laboratory conditions and, often, purified plasma cell membranes, which do not provide information on receptor localization or activity as these assays typically focus on measuring binding only. Here, we apply bioluminescence resonance energy transfer (BRET) in living cells to determine hormone-receptor interactions between a Gaussia luciferase (Gluc)-luteinizing hormone/chorionic gonadotropin receptor (LHCGR) fusion and its ligands (human chorionic gonadotropin or luteinizing hormone) fused to the enhanced green fluorescent protein (eGFP). The Gluc-LHCGR, as well as other Gluc-GPCRs such as the somatostatin and the C-X-cytokine 4 receptors, is expressed on the plasma membrane, where luminescence activity is equal to membrane receptor expression, and is fully functional. The chimeric eGFP-ligands are properly secreted from cells and able to bind and activate the wild-type LHCGR as well as the Gluc-LHCGR. Finally, BRET was used to determine the interactions between clinically relevant mutations of the hormones and the LHCGR, and show that this bioassay provides a fast and effective, safe and cost efficient tool to assist the molecular characterization of mutations in either the receptor or ligand, and it is compatible with downstream cellular assays to determine receptor activation/function.

Assessment of an Anticancer Effect of the Simultaneous Administration of MM-129 and Indoximod in the Colorectal Cancer Model

(1) Background: The purpose of the given study was to examine the antitumor activity of the simultaneous administration of MM-129, a 1,2,4-triazine derivative, and indoximod (IND), the kynurenine pathway inhibitor, toward colon cancer. (2) Methods: The efficiency of the co-administration of the studied compounds was assessed in xenografted zebrafish embryos. Then, the effects of the combined administration of compounds on cellular processes such as cell viability, apoptosis, and intracellular signaling pathways were evaluated. In vitro studies were performed using two colorectal cancer cell lines, namely, DLD-1 and HT-29. (3) Results: The results indicated that the simultaneous application of MM-129 and indoximod induced a stronger inhibition of tumor growth in zebrafish xenografts. The combination of these compounds intensified the process of apoptosis by lowering the mitochondrial potential, enhancing the externalization of phosphatidylserine (PS) and activation of caspases. Additionally, the expression of protein kinase B (AKT) and indoleamine 2,3-dioxygenase-(1IDO1) was disrupted under the applied compound combination. (4) Conclusions: Simultaneous targeting of ongoing cell signaling that promotes tumor progression, along with inhibition of the kynurenine pathway enzyme IDO1, results in the enhancement of the antitumor effect of the tested compounds against the colon cancer cells.

Synthetic circuits based on split Cas9 to detect cellular events

Synthetic biology involves the engineering of logic circuit gates that process different inputs to produce specific outputs, enabling the creation or control of biological functions. While CRISPR has become the tool of choice in molecular biology due to its RNA-guided targetability to other nucleic acids, it has not been frequently applied to logic gates beyond those controlling the guide RNA (gRNA). In this study, we present an adaptation of split Cas9 to generate logic gates capable of sensing biological events, leveraging a Cas9 reporter (EGxxFP) to detect occurrences such as cancer cell origin, epithelial to mesenchymal transition (EMT), and cell-cell fusion. First, we positioned the complementing halves of split Cas9 under different promoters-one specific to cancer cells of epithelial origin (phCEA) and the other a universal promoter. The use of self-assembling inteins facilitated the reconstitution of the Cas9 halves. Consequently, only cancer cells with an epithelial origin activated the reporter, exhibiting green fluorescence. Subsequently, we explored whether this system could detect biological processes such as epithelial to mesenchymal transition (EMT). To achieve this, we designed a logic gate where one half of Cas9 is expressed under the phCEA, while the other is activated by TWIST1. The results showed that cells undergoing EMT effectively activated the reporter. Next, we combined the two inputs (epithelial origin and EMT) to create a new logic gate, where only cancer epithelial cells undergoing EMT activated the reporter. Lastly, we applied the split-Cas9 logic gate as a sensor of cell-cell fusion, both in induced and naturally occurring scenarios. Each cell type expressed one half of split Cas9, and the induction of fusion resulted in the appearance of multinucleated syncytia and the fluorescent reporter. The simplicity of the split Cas9 system presented here allows for its integration into various cellular processes, not only as a sensor but also as an actuator.

Regulation of Notch1 Signalling by Long Non-Coding RNAs in Cancers and Other Health Disorders

Notch1 signalling plays a multifaceted role in tissue development and homeostasis. Currently, due to the pivotal role of Notch1 signalling, the relationship between NOTCH1 expression and the development of health disorders is being intensively studied. Nevertheless, Notch1 signalling is not only controlled at the transcriptional level but also by a variety of post-translational events. First is the ligand-dependent mechanical activation of NOTCH receptors and then the intracellular crosstalk with other signalling molecules-among those are long non-coding RNAs (lncRNAs). In this review, we provide a detailed overview of the specific role of lncRNAs in the modulation of Notch1 signalling, from expression to activity, and their connection with the development of health disorders, especially cancers.

Identification of a novel alternatively spliced isoform of the ribosomal uL10 protein

Alternative splicing is one of the key mechanisms extending the complexity of genetic information and at the same time adaptability of higher eukaryotes. As a result, the broad spectrum of isoforms produced by alternative splicing allows organisms to fine-tune their proteome; however, the functions of the majority of alternatively spliced protein isoforms are largely unknown. Ribosomal protein isoforms are one of the groups for which data are limited. Here we report characterization of an alternatively spliced isoform of the ribosomal uL10 protein, named uL10β. The uL10 protein constitutes the core element of the ribosomal stalk structure within the GTPase associated center, which represents the landing platform for translational GTPases - trGTPases. The stalk plays an important role in the ribosome-dependent stimulation of GTP by trGTPases, which confer unidirectional trajectory for the ribosome, allosterically contributing to the speed and accuracy of translation. We have shown that the newly identified uL10β protein is stably expressed in mammalian cells and is primarily located within the nuclear compartment with a minor signal within the cytoplasm. Importantly, uL10β is able to bind to the ribosomal particle, but is mainly associated with 60S and 80S particles; additionally, the uL10β undergoes re-localization into the mitochondria upon endoplasmic reticulum stress induction. Our results suggest a specific stress-related dual role of uL10β, supporting the idea of existence of specialized ribosomes with an altered GTPase associated center.

Optogenetic control of NOTCH1 signaling

The Notch signaling pathway is a crucial regulator of cell differentiation as well as tissue organization, whose deregulation is linked to the pathogenesis of different diseases. NOTCH1 plays a key role in breast cancer progression by increasing proliferation, maintenance of cancer stem cells, and impairment of cell death. NOTCH1 is a mechanosensitive receptor, where mechanical force is required to activate the proteolytic cleavage and release of the Notch intracellular domain (NICD). We circumvent this limitation by regulating Notch activity by light. To achieve this, we have engineered an optogenetic NOTCH1 receptor (optoNotch) to control the activation of NOTCH1 intracellular domain (N1ICD) and its downstream transcriptional activities. Using optoNotch we confirm that NOTCH1 activation increases cell proliferation in MCF7 and MDA-MB-468 breast cancer cells in 2D and spheroid 3D cultures, although causing distinct cell-type specific migratory phenotypes. Additionally, optoNotch activation induced chemoresistance on the same cell lines. OptoNotch allows the fine-tuning, ligand-independent, regulation of N1ICD activity and thus a better understanding of the spatiotemporal complexity of Notch signaling. Video Abstract.

Genetic variants of gonadotrophins and their receptors: Impact on the diagnosis and management of the infertile patient

This narrative review is concerned with genetic variants of the genes encoding gonadotrophin subunits and their receptors, as well as their implications into the diagnosis and treatment of infertility. We first review briefly the basics of molecular biology and biochemistry of gonadotrophin and gonadotrophin receptor structure and function, then describe the phenotypic effects of polymorphisms and mutations of these genes, followed by diagnostic aspects. We will then summarise the information that inactivating gonadotrophin receptor mutations have provided about the controversial topic of extragonadal gonadotrophin action. Finally, we will close with the current and future therapeutic approaches on patients with gonadotrophin and their receptor mutations.

Shooting at Moving and Hidden Targets-Tumour Cell Plasticity and the Notch Signalling Pathway in Head and Neck Squamous Cell Carcinomas

Head and Neck Squamous Cell Carcinoma (HNSCC) is often aggressive, with poor response to current therapies in approximately 40-50% of the patients. Current therapies are restricted to operation and irradiation, often combined with a small number of standard-of-care chemotherapeutic drugs, preferentially for advanced tumour patients. Only very recently, newer targeted therapies have entered the clinics, including Cetuximab, which targets the EGF receptor (EGFR), and several immune checkpoint inhibitors targeting the immune receptor PD-1 and its ligand PD-L1. HNSCC tumour tissues are characterized by a high degree of intra-tumour heterogeneity (ITH), and non-genetic alterations that may affect both non-transformed cells, such as cancer-associated fibroblasts (CAFs), and transformed carcinoma cells. This very high degree of heterogeneity likely contributes to acquired drug resistance, tumour dormancy, relapse, and distant or lymph node metastasis. ITH, in turn, is likely promoted by pronounced tumour cell plasticity, which manifests in highly dynamic and reversible phenomena such as of partial or hybrid forms of epithelial-to-mesenchymal transition (EMT), and enhanced tumour stemness. Stemness and tumour cell plasticity are strongly promoted by Notch signalling, which remains poorly understood especially in HNSCC. Here, we aim to elucidate how Notch signal may act both as a tumour suppressor and proto-oncogenic, probably during different stages of tumour cell initiation and progression. Notch signalling also interacts with numerous other signalling pathways, that may also have a decisive impact on tumour cell plasticity, acquired radio/chemoresistance, and metastatic progression of HNSCC. We outline the current stage of research related to Notch signalling, and how this pathway may be intricately interconnected with other, druggable targets and signalling mechanisms in HNSCC.

Abstract 79: Crosstalk of PIM and LKB1 kinases in driving growth of prostate cancer cells

The oncogenic PIM kinases and the tumor-suppressive LKB1 kinase have been linked to regulation of cell growth and proliferation. Here we have investigated their potential interactions as well as their relative impacts on tumorigenic growth of prostate cancer cells. The cellular functions of PIM and LKB1 kinases were evaluated using either pan-PIM inhibitors or CRISPR/Cas9-based genomic editing, with which all three PIM family members and/or LKB1 were knocked out from PC3 prostate cancer cells. In addition to cell-based 2D proliferation assays, we examined tumor growth using the chick embryo chorioallantoic membrane (CAM) xenograft model. In this report, we show that inhibition of PIM expression or activity results in increased phosphorylation of AMPK at Thr172 in an LKB1-dependent fashion. With in vitro kinase assays, we demonstrate that LKB1 is a novel direct substrate for PIM kinases and that Ser334 is one of the PIM target sites in LKB1. Accordingly, wild-type LKB1, but not the phosphodeficient S334A mutant can restore PIM inhibitor-induced AMPK phosphorylation in LKB1 knock-out cells. Whereas loss of LKB1 exaggerates formation of PC3-based tumors in the CAM xenograft model, co-deletion of PIM kinases attenuates it. The impairment of cell proliferation and tumor growth in cells lacking both PIM and LKB1 kinases not only underscores the potential crosstalk in signaling between these kinases, but also suggest that PIM inhibitors could be used to restrain growth of LKB1-deficient tumors.

Citation Format: Kwan Long Mung, William Eccleshall, Niina M. Santio, Adolfo Rivero-Müller, Cecilia Sahlgren, Päivi J. Koskinen. Crosstalk of PIM and LKB1 kinases in driving growth of prostate cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 79.

PIM kinases inhibit AMPK activation and promote tumorigenicity by phosphorylating LKB1

BACKGROUND

The oncogenic PIM kinases and the tumor-suppressive LKB1 kinase have both been implicated in the regulation of cell growth and metabolism, albeit in opposite directions. Here we investigated whether these kinases interact with each other to influence AMPK activation and tumorigenic growth of prostate and breast cancer cells.

METHODS

We first determined how PIM and LKB1 kinases affect AMPK phosphorylation levels. We then used in vitro kinase assays to demonstrate that LKB1 is phosphorylated by PIM kinases, and site-directed mutagenesis to identify the PIM target sites in LKB1. The cellular functions of PIM and LKB1 kinases were evaluated using either pan-PIM inhibitors or CRISPR/Cas9 genomic editing, with which all three PIM family members and/or LKB1 were knocked out from PC3 prostate and MCF7 breast cancer cell lines. In addition to cell proliferation assays, we examined the effects of PIM and/or LKB1 loss on tumor growth using the chick embryo chorioallantoic membrane (CAM) xenograft model.

RESULTS

We provide both genetic and pharmacological evidence to demonstrate that inhibition of PIM expression or activity increases phosphorylation of AMPK at Thr172 in both PC3 and MCF7 cells, but not in their derivatives lacking LKB1. This is explained by our observation that all three PIM family kinases can phosphorylate LKB1 at Ser334. Wild-type LKB1, but not its phosphodeficient derivative, can restore PIM inhibitor-induced AMPK phosphorylation in LKB1 knock-out cells. In the CAM model, loss of LKB1 enhances tumorigenicity of PC3 xenografts, while cells lacking both LKB1 and PIMs exhibit slower proliferation rates and form smaller tumors.

CONCLUSION

PIM kinases are novel negative regulators of LKB1 that affect AMPK activity in an LKB1-dependent fashion. The impairment of cell proliferation and tumor growth in cells lacking both LKB1 and PIMs indicates that these kinases possess a shared signaling role in the context of cancer. These data also suggest that PIM inhibitors may be a rational therapeutic option for LKB1-deficient tumors. Video Abstract.

An Improved Vector System for Homogeneous and Stable Gene Regulation

Precise analysis of the genetic expression and functioning of proteins requires experimental approaches that, among others, enable tight control of gene expression at the transcriptional level. Doxycycline-induced Tet-On/Tet-Off expression systems provide such an opportunity, and are frequently used to regulate the activity of genes in eukaryotic cells. Since its development, the Tet-system has evolved tight gene control in mammalian cells; however, some challenges are still unaddressed. In the current set up, the establishment of the standard Tet-based system in target cells is time-consuming and laborious and has been shown to be inefficient, especially in a long-term perspective. In this work, we present an optimized inducible expression system, which enables rapid generation of doxycycline-responsive cells according to a one- or two-step protocol. The reported modifications of the Tet-On system expand the toolbox for regulated mammalian gene expression and provide high, stable, and homogenous expression of the Tet-On3G transactivator, which is of fundamental importance in the regulation of transgenes.

PIM-induced phosphorylation of Notch3 promotes breast cancer tumorigenicity in a CSL-independent fashion

Dysregulation of the developmentally important Notch signaling pathway is implicated in several types of cancer, including breast cancer. However, the specific roles and regulation of the four different Notch receptors have remained elusive. We have previously reported that the oncogenic PIM kinases phosphorylate Notch1 and Notch3. Phosphorylation of Notch1 within the second nuclear localization sequence of its intracellular domain (ICD) enhances its transcriptional activity and tumorigenicity. In this study, we analyzed Notch3 phosphorylation and its functional impact. Unexpectedly, we observed that the PIM target sites are not conserved between Notch1 and Notch3. Notch3 ICD (N3ICD) is phosphorylated within a domain, which is essential for formation of a transcriptionally active complex with the DNA-binding protein CSL. Through molecular modeling, X-ray crystallography, and isothermal titration calorimetry, we demonstrate that phosphorylation of N3ICD sterically hinders its interaction with CSL and thereby inhibits its CSL-dependent transcriptional activity. Surprisingly however, phosphorylated N3ICD still maintains tumorigenic potential in breast cancer cells under estrogenic conditions, which support PIM expression. Taken together, our data indicate that PIM kinases modulate the signaling output of different Notch paralogs by targeting distinct protein domains and thereby promote breast cancer tumorigenesis via both CSL-dependent and CSL-independent mechanisms.

In vitro Targetability Validation of Peptide-Functionalized Mesoporous Silica Nanoparticles in the Presence of Serum Proteins

Demonstration of receptor-mediated targeting of nanoparticles to specific organs and/or cell types is an integral aim in many bionanomedicine development projects. However, engagement of targeted receptors with ligands on nanocarriers, which is the cornerstone of the active targeting concept, is challenging to study under biologically relevant conditions and thus often stays overlooked. In this work, we utilize an in-house established bioassay for in vitro targetability validation of mesoporous silica nanoparticles (MSNs), functionalized with high-affinity peptide ligands to somatostatin receptors via protective group chemistry, ensuring the correct orientation of the peptide's pharmacophore. We demonstrate that targeted nanoparticles, but not scrambled peptide-decorated counterparts, specifically engage the targeted receptors in living cells in culture media containing serum protein. The importance of being able to exclude false positives originating from the premature detachment of targeting peptides from the MSNs is highlighted.

iGIST-A Kinetic Bioassay for Pertussis Toxin Based on Its Effect on Inhibitory GPCR Signaling

Detection of pertussis toxin (PTX) activity is instrumental for the development and manufacturing of pertussis vaccines. These quality and safety measures require thousands of mice annually. Here, we describe Interference in Gαi-mediated Signal Transduction (iGIST), an animal-free kinetic bioassay for detection of PTX, by measuring its effect on inhibitory G protein-coupled receptor (GPCR) signaling. PTX ADP-ribosylates inhibitory α-subunits of the heterotrimeric G proteins, thereby perturbing the inhibitory GPCR signaling. iGIST is based on HEK293 cells coexpressing a somatostatin receptor 2 (SSTR2), which is an inhibitory GPCR controllable by a high-affinity agonist octreotide; and a luminescent 3'5'-cyclic adenosine monophosphate (cAMP) probe. iGIST has a low sensitivity threshold in the pg/mL range of PTX, surpassing by 100-fold in a parallel analysis the currently used in vitro end-point technique to detect PTX, the cluster formation assay (CFA) in Chinese hamster ovary cells. iGIST also detects PTX in complex samples, i.e., a commercial PTX-toxoid-containing pertussis vaccine that was spiked with an active PTX. iGIST has an objective digital readout and is observer independent, offering prospects for automation. iGIST emerges as a promising animal-free alternative to detect PTX activity in the development and manufacturing of pertussis vaccines. iGIST is also expected to facilitate basic PTX research, including identification and characterization of novel compounds interfering with PTX.

Membrane Estrogen Receptor (GPER) and Follicle-Stimulating Hormone Receptor (FSHR) Heteromeric Complexes Promote Human Ovarian Follicle Survival

Classically, follicle-stimulating hormone receptor (FSHR)-driven cAMP-mediated signaling boosts human ovarian follicle growth and oocyte maturation. However, contradicting in vitro data suggest a different view on physiological significance of FSHR-mediated cAMP signaling. We found that the G-protein-coupled estrogen receptor (GPER) heteromerizes with FSHR, reprogramming cAMP/death signals into proliferative stimuli fundamental for sustaining oocyte survival. In human granulosa cells, survival signals are missing at high FSHR:GPER ratio, which negatively impacts follicle maturation and strongly correlates with preferential Gαs protein/cAMP-pathway coupling and FSH responsiveness of patients undergoing controlled ovarian stimulation. In contrast, FSHR/GPER heteromers triggered anti-apoptotic/proliferative FSH signaling delivered via the Gβγ dimer, whereas impairment of heteromer formation or GPER knockdown enhanced the FSH-dependent cell death and steroidogenesis. Therefore, our findings indicate how oocyte maturation depends on the capability of GPER to shape FSHR selective signals, indicating hormone receptor heteromers may be a marker of cell proliferation.

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G-protein-coupled estrogen receptor (GPER) interacts with FSH receptor (FSHR)

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FSHR/GPER heteromers reprogram FSH-induced death signals to proliferative stimuli

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Anti-apoptotic signaling of heteromers is via a GPER-Gαs inhibitory complex and Gβγ

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Heteromer formation impacts follicle maturation and FSH responses of IVF patients

A novel bioassay for quantification of surface Cannabinoid receptor 1 expression

The cannabinoid receptor type 1 (CB1) plays critical roles in multiple physiological processes such as pain perception, brain development and body temperature regulation. Mutations on this gene (CNR1), results in altered functionality and/or biosynthesis such as reduced membrane expression, changes in mRNA stability or changes in downstream signaling that act as triggers for diseases such as obesity, Parkinson’s, Huntington’s, among others; thus, it is considered as a potential pharmacological target. To date, multiple quantification methods have been employed to determine how these mutations affect receptor expression and localization; however, they present serious disadvantages that may arise quantifying errors. Here, we describe a sensitive bioassay to quantify receptor surface expression; in this bioassay the Gaussia Luciferase (GLuc) was fused to the extracellular portion of the CB1. The GLuc activity was assessed by coelenterazine addition to the medium followed by immediate readout. Based on GLuc activity assay, we show that the GLuc signals corelate with CB1 localization, besides, we showed the assay’s functionality and reliability by comparing its results with those generated by previously reported mutations on the CNR1 gene and by using flow cytometry to determine the cell surface receptor expression. Detection of membrane-bound CB1, and potentially other GPCRs, is able to quickly screen for receptor levels and help to understand the effect of clinically relevant mutations or polymorphisms.

OR24-04 Ovarian Follicle Survival Is Determined by Follicle-Stimulating Hormone Receptor (FSHR) and Estrogen Receptor (GPER) Heteromers

Mechanisms regulating the selection of antral ovarian follicles are poorly understood and supposed to rely on low estrogen levels, decline of follicle-stimulating hormone (FSH) levels and receptor (FSHR) expression. These concepts are challenged in vitro, where apoptosis of human granulosa cells (hGLC) and transfected cell lines is induced by high doses of FSH or FSHR overexpression, while estrogens induce anti-apoptotic signals via nuclears and a G protein-coupled estrogen receptor (GPER). Therefore, in vitro data suggest that antral follicle selection may be driven by underestimated, FSH/FSHR-dependent apoptotic signals due to transiently maximized FSHR expression and overload of cAMP signalling, prevailing on estrogen-dependent signals. Here we demonstrate how FSHR/GPER physical interaction rescue ovarian follicles from FSH-mediated death. 10 nM FSH induces high intracellular levels of cAMP, measured by bioluminescence resonance energy transfer (BRET), and apoptosis in cultured hGLC under conditions where GPER levels are depleted by siRNA. This result was confirmed in transfected HEK293 cells overexpressing FSHR. Using BRET, photo-activated localization microscopy (PALM) and bioinformatics prodiction, we also demonstrate FSHR/GPER heteromers at the cell surface. The role of FSHR/GPER heteromers may be relevant to inhibit FSH-induced death signals, since increasing GPER expression levels in HEK293 cells co-expressing FSHR results in displacement of the Gαs-protein to FSHR, blockade of FSH-induced cAMP production and inhibition of apoptosis. However, in HEK293 cells coexpressing GPER/FSHR, FSH-induced activation of the anti-apoptotic AKT-pathway via a Gβγ-dependent mechanism, as demonstrated by Western blotting in cells treated using the inhibitor gallein. Inhibition of both FSH-induced cAMP production and apoptosis was lost when FSHR is coexpressed together with a mutant GPER, unable to heteromerize with FSHR, as well as in KO HEK293 cells unable to produce a molecular complex associated with GPER inhibiting cAMP. GPER/FSHR coexpression is confirmed in secondary follicles from paraffin-embedded tissues of human ovary by immunohistochemistry, suggesting that FSHR-GPER heterodimers could be physiologically relevant in vivo for inhibiting cAMP-linked apoptosis. Most importantly, FSHR and GPER co-expression correlates in hGLC from FSH-normo-responder women undergoing assisted reproduction, while it is not in hGLC from FSH-poor-responders, where increasing FSHR mRNA levels do not correspond to increasing GPER mRNA levels. We demonstrate that death signals in atretic follicles are delivered through overexpressed FSHR and inhibited by FSHR/GPER heteromerization, activating anti-apoptotic pathways. This finding unveils a novel working model of the physiology of dominant follicle selection and the relationship between FSH and estrogens.

Imperatorin as a Promising Chemotherapeutic Agent Against Human Larynx Cancer and Rhabdomyosarcoma Cells

Naturally occurring coumarins are bioactive compounds widely used in Asian traditional medicine. They have been shown to inhibit proliferation, induce apoptosis, and/or enhance the cytotoxicity of currently used drugs against a variety of cancer cell types. The aim of our study was to examine the antiproliferative activity of different linear furanocoumarins on human rhabdomyosarcoma, lung, and larynx cancer cell lines, and dissolve their cellular mechanism of action. The coumarins were isolated from fruits of Angelica archangelica L. or Pastinaca sativa L., and separated using high-performance counter-current chromatography (HPCCC). The identity and purity of isolated compounds were confirmed by HPLC-DAD and NMR analyses. Cell viability and toxicity assessments were performed by means of methylthiazolyldiphenyl-tetrazolium bromide (MTT) and lactate dehydrogenase (LDH) assays, respectively. Induction of apoptosis and cell cycle progression were measured using flow cytometry analysis. qPCR method was applied to detect changes in gene expression. Linear furanocoumarins in a dose-dependent manner inhibited proliferation of cancer cells with diverse activity regarding compounds and cancer cell type specificity. Imperatorin (IMP) exhibited the most potent growth inhibitory effects against human rhabdomyosarcoma and larynx cancer cell lines owing to inhibition of the cell cycle progression connected with specific changes in gene expression, including CDKN1A. As there are no specific chemotherapy treatments dedicated to laryngeal squamous cell carcinoma and rhabdomyosarcoma, and IMP seems to be non-toxic for normal cells, our results could open a new direction in the search for effective anti-cancer agents.

Genetically Engineered Lung Cancer Cells for Analyzing Epithelial-Mesenchymal Transition

Cell plasticity, defined as the ability to undergo phenotypical transformation in a reversible manner, is a physiological process that also exerts important roles in disease progression. Two forms of cellular plasticity are epithelial-mesenchymal transition (EMT) and its inverse process, mesenchymal-epithelial transition (MET). These processes have been correlated to the poor outcome of different types of neoplasias as well as drug resistance development. Since EMT/MET are transitional processes, we generated and validated a reporter cell line. Specifically, a far-red fluorescent protein was knocked-in in-frame with the mesenchymal gene marker VIMENTIN (VIM) in H2170 lung cancer cells. The vimentin reporter cells (VRCs) are a reliable model for studying EMT and MET showing cellular plasticity upon a series of stimulations. These cells are a robust platform to dissect the molecular mechanisms of these processes, and for drug discovery in vitro and in vivo in the future.

Vimentin regulates Notch signaling strength and arterial remodeling in response to hemodynamic stress

The intermediate filament (IF) cytoskeleton has been proposed to regulate morphogenic processes by integrating the cell fate signaling machinery with mechanical cues. Signaling between endothelial cells (ECs) and vascular smooth muscle cells (VSMCs) through the Notch pathway regulates arterial remodeling in response to changes in blood flow. Here we show that the IF-protein vimentin regulates Notch signaling strength and arterial remodeling in response to hemodynamic forces. Vimentin is important for Notch transactivation by ECs and vimentin knockout mice (VimKO) display disrupted VSMC differentiation and adverse remodeling in aortic explants and in vivo. Shear stress increases Jagged1 levels and Notch activation in a vimentin-dependent manner. Shear stress induces phosphorylation of vimentin at serine 38 and phosphorylated vimentin interacts with Jagged1 and increases Notch activation potential. Reduced Jagged1-Notch transactivation strength disrupts lateral signal induction through the arterial wall leading to adverse remodeling. Taken together we demonstrate that vimentin forms a central part of a mechanochemical transduction pathway that regulates multilayer communication and structural homeostasis of the arterial wall.

Compound heterozygous mutations in the luteinizing hormone receptor signal peptide causing 46,XY disorder of sex development

Testosterone production by the fetal testis depends on a functional relationship between hCG and the LH/chorionic gonadotropin receptor (LHCGR). Failure of the receptor to correctly respond to its ligand leads to impaired sexual differentiation in males. A phenotypically female patient with pubertal delay had a 46,XY karyotype and was diagnosed with 46,XY disorder of sex development (DSD). Novel compound heterozygous LHCGR mutations were found in the signal peptide: a duplication p.L10_Q17dup of maternal origin, and a deletion (p.K12_L15del) and a p.L16Q missense mutation of paternal origin. cAMP production was very low for both the deletion and duplication mutations and was halved for the missense mutant. The duplication and missense mutations were both expressed intracellularly, but at very low levels at the cell membrane; they were most likely retained in the endoplasmic reticulum. The deletion mutant had a very limited intracellular expression, indicating impaired biosynthesis. There was reduced expression of all three mutants, which was most marked for the deletion mutation. There was also decreased protein expression of all three mutant receptors. In the deletion mutation, the presence of a lower-molecular-weight band corresponding to LHCGR monomer, probably due to lack of glycosylation, and a lack of bands corresponding to dimers/oligomers suggests absent ER entry. This novel case of 46,XY DSD illustrates how different LHCGR signal peptide mutations led to complete receptor inactivation by separate mechanisms. The study underlines the importance of specific regions of signal peptides and expands the spectrum of LHCGR mutations.

The gonadotropin system, lessons from animal models and clinical cases

This review article centers upon family of gonadotropin hormones which consists of two pituitary hormones - follicle-stimulating hormone (FSH) and luteinizing hormone (LH) as well as one non-pituitary hormone - human chorionic gonadotropin (hCG) secreted by placenta, and their receptors. Gonadotropins play an essential role in proper sexual development, puberty, gametogenesis, maintenance of pregnancy and male sexual differentiation during the fetal development. They belong to the family of glycoprotein hormones thus they constitute heterodimeric proteins built of common α subunit and hormone-specific β-subunit. Hitherto, several mutations in genes encoding both gonadotropins and their receptors have been identified in humans. Their occurrence resulted in a number of different phenotypes including delayed puberty, primary amenorrhea, hermaphroditism, infertility and hypogonadism. In order to understand the effects of mutations on the phenotype observed in affected patients, detailed molecular studies are required to map the relationship between the structure and function of gonadotropins and their receptors. Nonetheless, in vitro assays are often insufficient to understand physiology. Therefore, several animal models have been developed to unravel the physiological roles of gonadotropins and their receptors.

Targeting Somatostatin Receptors By Functionalized Mesoporous Silica Nanoparticles - Are We Striking Home?

The concept of delivering nanoformulations to desired tissues by means of targeting membrane receptors of high local abundance by ligands anchored to the nanocarrier has gained a lot of attention over the last decade. Currently, there is no unanimous opinion on whether surface functionalization of nanocarriers by targeting ligands translates into any real benefit in terms of pharmacokinetics or treatment outcomes. Having examined the published nanocarriers designed to engage with somatostatin receptors, we realized that in the majority of cases targetability claims were not supported by solid evidence of targeting ligand-targeted receptor coupling, which is the very crux of a targetability concept. Here, we present an approach to characterize targetability of mesoporous silica-based nanocarriers functionalized with ligands of somatostatin receptors. The targetability proof in our case comes from a functional assay based on a genetically-encoded cAMP probe, which allows for real-time capture of receptor activation in living cells, triggered by targeting ligands on nanoparticles. We elaborate on the development and validation of the assay, highlighting the power of proper functional tests in the characterization pipeline of targeted nanoformulations.

FSHR Trans-Activation and Oligomerization

Follicle stimulating hormone (FSH) plays a key role in human reproduction through, among others, induction of spermatogenesis in men and production of estrogen in women. The function FSH is performed upon binding to its cognate receptor-follicle-stimulating hormone receptor (FSHR) expressed on the surface of target cells (granulosa and Sertoli cells). FSHR belongs to the family of G protein-coupled receptors (GPCRs), a family of receptors distinguished by the presence of various signaling pathway activation as well as formation of cross-talking aggregates. Until recently, it was claimed that the FSHR occurred naturally as a monomer, however, the crystal structure as well as experimental evidence have shown that FSHR both self-associates and forms heterodimers with the luteinizing hormone/chorionic gonadotropin receptor-LHCGR. The tremendous gain of knowledge is also visible on the subject of receptor activation. It was once thought that activation occurs only as a result of ligand binding to a particular receptor, however there is mounting evidence of trans-activation as well as biased signaling between GPCRs. Herein, we describe the mechanisms of aforementioned phenomena as well as briefly describe important experiments that contributed to their better understanding.

The snapping shrimp dactyl plunger: a thermomechanical damage-tolerant sandwich composite

The dactyl plunger of Alpheus sp. was found to be a layered composite, with mineral-rich outer and inner layers and a chitin-rich middle layer of high porosity. The chitin-rich middle layer is itself composed of several porous chitin laminae. Modelling heat conduction through the plunger cross-section revealed that the chitin-rich layer is able to insulate heat and retard its progress through the material. Heat accumulates in the plunger after a series of successive snaps and as such, its thermally resistant design can be considered most useful under the conditions of successive snapping. The plunger has a concurrent mechanical damage-tolerant design with biogenic mineral layers, viscous (chitin-mineral) interfaces, energy-dissipating porous chitin, and sidewalls composed of ordered, layered aragonite. The snapping shrimp plunger has a design that may protect it and internal soft tissues from thermomechanical damage during plunger-socket compression prior to cavitation bubble release.

How to Train a Cell-Cutting-Edge Molecular Tools

In biological systems, the formation of molecular complexes is the currency for all cellular processes. Traditionally, functional experimentation was targeted to single molecular players in order to understand its effects in a cell or animal phenotype. In the last few years, we have been experiencing rapid progress in the development of ground-breaking molecular biology tools that affect the metabolic, structural, morphological, and (epi)genetic instructions of cells by chemical, optical (optogenetic) and mechanical inputs. Such precise dissection of cellular processes is not only essential for a better understanding of biological systems, but will also allow us to better diagnose and fix common dysfunctions. Here, we present several of these emerging and innovative techniques by providing the reader with elegant examples on how these tools have been implemented in cells, and, in some cases, organisms, to unravel molecular processes in minute detail. We also discuss their advantages and disadvantages with particular focus on their translation to multicellular organisms for in vivo spatiotemporal regulation. We envision that further developments of these tools will not only help solve the processes of life, but will give rise to novel clinical and industrial applications.

A vital region for human glycoprotein hormone trafficking revealed by an LHB mutation

Glycoprotein hormones are complex hormonally active macromolecules. Luteinizing hormone (LH) is essential for the postnatal development and maturation of the male gonad. Inactivating Luteinizing hormone beta (LHB) gene mutations are exceptionally rare and lead to hypogonadism that is particularly severe in males. We describe a family with selective LH deficiency and hypogonadism in two brothers. DNA sequencing of LHB was performed and the effects of genetic variants on hormone function and secretion were characterized by mutagenesis studies, confocal microscopy and functional assays. A 20-year-old male from a consanguineous family had pubertal delay, hypogonadism and undetectable LH. A homozygous c.118_120del (p.Lys40del) mutation was identified in the patient and his brother, who subsequently had the same phenotype. Treatment with hCG led to pubertal development, increased circulating testosterone and spermatogenesis. Experiments in HeLa cells revealed that the mutant LH is retained intracellularly and showed diffuse cytoplasmic distribution. The mutated LHB heterodimerizes with the common alpha-subunit and can activate its receptor. Deletion of flanking glutamic acid residues at positions 39 and 41 impair LH to a similar extent as deletion of Lys40. This region is functionally important across all heterodimeric glycoprotein hormones, because deletion of the corresponding residues in hCG, follicle-stimulating hormone and thyroid-stimulating hormone beta-subunits also led to intracellular hormone retention. This novel LHB mutation results in hypogonadism due to intracellular sequestration of the hormone and reveals a discrete region in the protein that is crucial for normal secretion of all human glycoprotein hormones.

Keratin 8-deletion induced colitis predisposes to murine colorectal cancer enforced by the inflammasome and IL-22 pathway

Keratins (K) are intermediate filament proteins important in protection from cellular stress. K8, K18 and K19 are the main components of keratin filaments in colonic epithelia but their role in intestinal diseases remains ambiguous. A function for keratins in intestinal health is supported by the K8-knock-out (K8(-/-)) mouse which manifests an early chronic ulcerative colitis-like inflammatory bowel disease and epithelial hyperproliferation. We tested whether K8(-/-) mice are more susceptible to colorectal cancer (CRC) compared to K8 wild type (K8(+/+)), and K8 heterozygote (K8(+/-)) mice showing increased proliferation but no inflammation. K8(-/-) mice did not develop CRC spontaneously, but had dramatically increased numbers of tumors in the distal colon in the azoxymethane (AOM) and Apc(Min/+) CRC models while neither K8(+/+) nor K8(+/-) mice were susceptible. Upregulation of IL-22 in combination with a complete loss of its negative regulator IL-22BP, and increased downstream STAT3-signaling in K8(-/-) and K8(-/-)Apc(Min/+) colonic epithelia confirmed that the IL-22 pathway, important in inflammation, proliferation and tissue regeneration, was activated. The nearly total loss of IL-22BP correlated with an activated inflammasome leading to increased cleaved caspase-1, and the putative IL-22BP inhibitor, IL-18, as well as a decrease in ALDH1/2. Ablation of K8 in a colorectal cancer cell line similarly resulted in increased IL-18 and decreased ALDH1/2. K8/K18 co-immunoprecipitated with pro-caspase-1, a component of the inflammasome in the colon, which suggests that keratins modulate inflammasome activity and protect the colon from inflammation and tumorigenesis. The K8-null mouse models also provide novel epithelial-derived robust colon-specific CRC models.

Genetically-encoded tools for cAMP probing and modulation in living systems

Intracellular 3′-5′-cyclic adenosine monophosphate (cAMP) is one of the principal second messengers downstream of a manifold of signal transduction pathways, including the ones triggered by G protein-coupled receptors. Not surprisingly, biochemical assays for cAMP have been instrumental for basic research and drug discovery for decades, providing insights into cellular physiology and guiding pharmaceutical industry. However, despite impressive track record, the majority of conventional biochemical tools for cAMP probing share the same fundamental shortcoming—all the measurements require sample disruption for cAMP liberation. This common bottleneck, together with inherently low spatial resolution of measurements (as cAMP is typically analyzed in lysates of thousands of cells), underpin the ensuing limitations of the conventional cAMP assays: (1) genuine kinetic measurements of cAMP levels over time in a single given sample are unfeasible; (2) inability to obtain precise information on cAMP spatial distribution and transfer at subcellular levels, let alone the attempts to pinpoint dynamic interactions of cAMP and its effectors. At the same time, tremendous progress in synthetic biology over the recent years culminated in drastic refinement of our toolbox, allowing us not only to bypass the limitations of conventional assays, but to put intracellular cAMP life-span under tight control—something, that seemed scarcely attainable before. In this review article we discuss the main classes of modern genetically-encoded tools tailored for cAMP probing and modulation in living systems. We examine the capabilities and weaknesses of these different tools in the context of their operational characteristics and applicability to various experimental set-ups involving living cells, providing the guidance for rational selection of the best tools for particular needs.

Diatom-inspired skeletonisation of insulin - Mechanistic insights into crystallisation and extracellular bioactivity

In this paper, we encage insulin within calcium carbonate by means of a biomineralisation process. We find that both dogbone and crossbone morphologies develop during the crystallisation process. The crystals break down into small nanocrystals after prolonged immersion in phosphate buffer solution, which adhere extracellularly to mammalian cells without causing any observable damage or early cell-death. The mechanisms behind calcium carbonate encaging of single insulin monomers are detailed. This communication elucidates a novel, diatom-inspired approach to the mineral skeletonisation of insulin.

A novel inactivating mutation of the LH/chorionic gonadotrophin receptor with impaired membrane trafficking leading to Leydig cell hypoplasia type 1

OBJECTIVE

The LH/chorionic gonadotrophin receptor (LHCGR) is a G protein-coupled receptor (GPCR) that plays a central role in male sexual differentiation, regulation of ovarian follicular maturation, ovulation and maintenance of corpus luteum and pregnancy, as well as maintenance of testicular testosterone production. Mutations in the LHCGR gene are very rare. The aim of this work was to study the clinical and molecular characteristics of a rare familial LHCGR mutation.

METHODS

Five affected members of a family, including a phenotypically female, but genotypically male (46,XY), patient with Leydig cell hypoplasia type 1 and four genotypically female siblings with reproductive abnormalities, were studied genetically. Cell trafficking studies as well as signalling studies of mutated receptor were performed.

RESULTS

The five affected patients were all homozygous for a novel mutation in the LHCGR gene, a deletion of guanine in position 1850 (1850delG). This resulted in a frameshift affecting most of the C-terminal intracellular domain. In vitro studies demonstrated that the 1850delG receptor was completely incapable of transit to the cell membrane, becoming trapped within the endoplasmic reticulum. This could not be rescued by small-molecule agonist treatment or stimulated intracellularly by co-expression of a yoked human chorionic gonadotrophin.

CONCLUSIONS

This novel LHCGR mutation leads to complete inactivation of the LHCGR receptor due to trafficking and signalling abnormalities, which improves our understanding of the impact of the affected structural domain on receptor trafficking and function.

Comprehensive review on betulin as a potent anticancer agent

Numerous plant-derived substances, and their derivatives, are effective antitumour and chemopreventive agents. Yet, there are also a plethora of tumour types that do not respond, or become resistant, to these natural substances. This requires the discovery of new active compounds. Betulin (BE) is a pentacyclic triterpene and secondary metabolite of plants abundantly found in the outer bark of the birch tree Betulaceae sp. BE displays a broad spectrum of biological and pharmacological properties, among which the anticancer and chemopreventive activity attract most of the attention. In this vein, BE and its natural and synthetic derivatives act specifically on cancer cells with low cytotoxicity towards normal cells. Although the antineoplastic mechanism of action of BE is not well understood yet, several interesting aspects of BE's interactions are coming to light. This review will summarize the anticancer and chemopreventive potential of BE in vitro and in vivo by carefully dissecting and comparing the doses and tumour lines used in previous studies, as well as focusing on mechanisms underlying its activity at cellular and molecular level, and discuss future prospects.

CANDLES, an assay for monitoring GPCR induced cAMP generation in cell cultures

Background

G protein-coupled receptors (GPCRs) represent a physiologically and pharmacologically important family of receptors that upon coupling to Gα_S stimulate cAMP production catalyzed by adenylyl cyclase. Thus, developing assays to monitor cAMP production is crucial to screen for ligands in studies of GPCR signaling. Primary cell cultures represent a more robust model than cell lines to study GPCR signaling since they physiologically resemble the parent tissue. Current cAMP assays have two fundamental limitations: 1) absence of cAMP kinetics as competition-based assays require cell lysis and measure only a single time-point, and 2) high variation with separate samples needed to measure consecutive time points. The utility of real-time cAMP biosensors is also limited in primary cell cultures due to their poor transfection efficiency, variable expression levels and inability to select stable clones. We therefore, decided to develop an assay that can measure cAMP not only at a single time-point but the entire cAMP kinetics after GPCR activation in untransfected primary cells.

Results

CANDLES (Cyclic AMP iNdirect Detection by Light Emission from Sensor cells) assay for monitoring cAMP kinetics in cell cultures, particularly in primary cultures was developed. The assay requires co-culturing of primary cells with sensor cells that stably express a luminescent cAMP sensor. Upon GPCR activation in primary cells, cAMP is transferred to sensor cells via gap junction channels, thereby evoking a luminescent read-out. GPCR activation using primary cultures of rat cortical neurons and mouse granulosa cells was measured. Kinetic responses of different agonists to adrenergic receptors were also compared using rat cortical neurons. The assay optimization was done by varying sensor-test cell ratio, using phosphodiesterase inhibitors and testing cell-cell contact requirement.

Conclusions

Here we present CANDLES assay based on co-culturing test cells with cAMP-detecting sensor cells. This co-culture setup allows kinetic measurements, eliminates primary cell transfections and reduces variability. A variety of cell types (rat cortical neurons, mouse granulosa cells and established cell lines) and receptors (adrenergic, follicle stimulating hormone and luteinizing hormone/chorionic gonadotropin receptors) were tested for use with CANDLES. The assay is best applied while comparing cAMP generation curves upon different drug treatments to untransfected primary cells.

Electronic supplementary material

The online version of this article (doi:10.1186/s12964-014-0070-x) contains supplementary material, which is available to authorized users.

Transgenic GATA-4 expression induces adrenocortical tumorigenesis in C57Bl/6 mice

A link between elevated luteinizing hormone (LH) levels, GATA-4 and LH receptor (LHCGR) expression and gonadotropin-dependent adrenocortical tumorigenesis in humans and mice has been shown. To assess the mechanistic tumorigenic interrelationships between these factors, we transgenically expressed Gata4 under the 21-hydroxylase promoter (Cyp21a1, 21-OH) in C57Bl/6N mice. There was a gradual age-dependent increase of GATA-4 expression only in 21-OH-GATA-4 (TG) female adrenals, in association with slowly progressing neoplasia of non-steroidogenic spindle-shaped A cells in the subcapsular cortex. Gonadectomy (GDX), apparently through direct action of elevated serum LH, markedly enhanced the adrenocortical neoplasia, which now also appeared in GDX TG males. The neoplastic areas of the post-GDX TG adrenals contained, besides A cells, larger lipid-laden, steroidogenically active and LHCGR-positive B cells. Prolonged (>10 months) exposure to elevated post-GDX LH levels resulted in formation of adrenocortical adenomas in the TG mice. Intact and GDX TG mouse adrenals displayed elevated FOG-2 and decreased GATA-6 expression. Additionally, increased expression/activation of components of the Inhbb-Acvr2a-Acvr1c-Smad2/3 signaling system was observed in 12-month-old GDX TG adrenals. Our findings show that two distinct GATA-4-dependent populations of neoplastic adrenocortical cells form: non-steroidogenic LH-independent A cells and steroidogenic LH-dependent B cells.

A novel treatment strategy for ovarian cancer based on immunization against zona pellucida protein (ZP) 3

We tested the principle of treating malignant ovarian tumors by vaccination against their ectopically expressed protein, zona pellucida glycoprotein (ZP) 3, using as the experimental model the granulosa cell tumors that develop in transgenic mice expressing the simian virus 40 T-antigen under the inhibin-α promoter (inhα/Tag). We found high ZP3 expression in granulosa cell tumors of the transgenic mice, in human surface ovarian cancer and granulosa cell lines, and in human granulosa cell tumors and their metastases. Early preventive immunization (between 2 and 5.5 mo of age) of transgenic mice with recombinant human (rh) ZP3 prevented ovarian tumorigenesis, and delayed therapeutic immunization (between 4.5 and 7 mo) reduced weights of existing tumors by 86 and 75%, respectively (P<0.001), compared to vehicle-treated control mice. No objective side effects of the immunizations were observed. Liver metastases were found in nontreated/vehicle-treated controls (n=7/39), but none following active rhZP3 immunizations (n=0/36; P<0.05). Immunization with rhZP3 was highly effective, as demonstrated by the induction of anti-ZP3 antibodies, as well as proliferative responses to the ZP3 antigen. These results signal rhZP3 immunization as a novel strategy to be developed for the immunotherapy of ovarian granulosa cell tumors, as well as for that of other malignancies that may express ZP3.

Enhanced LH action in transgenic female mice expressing hCGbeta-subunit induces pituitary prolactinomas; the role of high progesterone levels

The etiology of pituitary adenomas remains largely unknown, with the exception of involvement of estrogens in the formation of prolactinomas. We have examined the molecular pathogenesis of prolactin-producing pituitary adenomas in transgenic female mice expressing the human choriongonadotropin (hCG) beta-subunit. The LH/CG bioactivity is elevated in the mice, with consequent highly stimulated ovarian progesterone (P(4)) production, in the face of normal estrogen secretion. Curiously, despite normal estrogen levels, large prolactinomas developed in these mice, and we provide here several lines of evidence that the elevated P(4) levels are involved in the growth of these estrogen-dependent tumors. The antiprogestin mifepristone inhibited tumor growth, and combined postgonadectomy estradiol/P(4) treatment was more effective than estrogen alone in inducing tumor growth. Evidence for direct growth-promoting effect of P(4) was obtained from cultures of primary mouse pituitary cells and rat somatomammotroph GH3 cells. The mouse tumors and cultured cells revealed stimulation of the cyclin D1/cyclin-dependent kinase 4/retinoblastoma protein/transcription factor E2F1 pathway in the growth response to P(4). If extrapolated to humans, and given the importance of endogenous P(4) and synthetic progestins in female reproductive functions and their pharmacotherapy, it is relevant to revisit the potential role of these hormones in the origin and growth of prolactinomas.

Inhibition of Akt signaling by the lignan matairesinol sensitizes prostate cancer cells to TRAIL-induced apoptosis

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) has been shown to be selectively pro-apoptotic in cancer cells, with minimal toxicity to normal tissues. Although this feature makes TRAIL a promising anticancer agent, not all cancer cell types are sensitive to TRAIL-induced apoptosis despite abundant expression of TRAIL receptors. Thus, combinatorial treatments to sensitize tumor cells to TRAIL-induced apoptosis have been in the focus of extensive research. Dietary lignans have shown cancer preventive and antitumorigenic activity, but the mechanisms behind these effects are poorly known. Here we observed that of the three tested lignan molecules, matairesinol (MAT) was the most effective as a death receptor-sensitizing agent. MAT sensitized the androgen-dependent LNCaP cells to TRAIL-induced apoptosis both in the presence and absence of androgens. Treatment with MAT markedly decreased Akt activity, which has been implicated as a key signaling mechanism in the TRAIL resistance of LNCaP prostate cancer cells. The involvement of the pathway in the MAT-mediated sensitization was shown in rescue experiments using ectopic expression of constitutively active Akt. Owing to the high activity of phosphatidylinositol 3-kinase/Akt signaling in cancer, targeting this survival pathway with MAT could markedly benefit TRAIL-based tumor therapies, including those aimed at prostate cancer.

Targeted therapy for adrenocortical tumors in transgenic mice through their LH receptor by Hecate-human chorionic gonadotropin beta conjugate

Novel strategies are needed for the treatment of adrenocortical tumors that are usually resistant to chemotherapy. Hecate, a 23-amino acid lytic peptide, was conjugated to the 15-amino acid (81-95) fragment of the human chorionic gonadotropin beta (CGbeta) chain, which would selectively kill cancer cells expressing the LH receptor (LHR) sparing the normal ones with LHR. To prove the principle that Hecate-CGbeta conjugate may eradicate tumors ectopically expressing plasma membrane receptors, transgenic (TG) inhibin alpha-subunit promoter (inhalpha)/Simian Virus 40 T-antigen mice, expressing LHR in their adrenal gland tumors, were used as the experimental model. Wild-type control littermates and TG mice with adrenal tumors were treated with either Hecate or Hecate-CGbeta conjugate at the age of 6.5 months for 3 weeks and killed 7 days after the last treatment. The Hecate-CGbeta conjugate reduced the adrenal tumor burden significantly in TG male but not in female mice, in comparison with Hecate-treated mice. Hecate-CGbeta conjugate treatment did not affect normal adrenocortical function as the serum corticosterone level between Hecate and Hecate-CGbeta conjugate groups were similar. The mRNA and protein expressions of GATA-4 and LHR colocalized only in tumor area, and a significant downregulation of gene expression was found after the Hecate-CGbeta conjugate in comparison with Hecate- and/or non-treated adrenal tumors by western blotting. This finding provides evidence for a selective destruction of the tumor cells by the Hecate-CGbeta conjugate. Hereby, our findings support the principle that Hecate-CGbeta conjugate is able to specifically destroy tumor cells that ectopically express LHR.

Assisted large fragment insertion by Red/ET-recombination (ALFIRE)--an alternative and enhanced method for large fragment recombineering

Functional genomics require manipulation and modification of large fragments of the genome. Such manipulation has only recently become more efficient due to the discovery of different techniques based on homologous recombination. However, certain limitations of these strategies still exist since insertion of homology arms (HAs) is often based on amplification of DNA sequences with PCR. Large quantities of PCR products longer than 4–5 kb can be difficult to obtain and the risk of mutations or mismatches increases with the size of the template that is being amplified. This can be overcome by adding HAs by conventional cloning techniques, but with large fragments such as entire genes the procedure becomes time-consuming and tedious. Second, homologous recombination techniques often require addition of antibiotic selection genes, which may not be desired in the final construct. Here, we report a method to overcome the size and selection marker limitations by a two- or three-step procedure. The method can insert any fragment into small or large episomes, without the need of an antibiotic selection gene. We have humanized the mouse luteinizing hormone receptor gene (Lhcgr) by inserting a ∼55 kb fragment from a BAC clone containing the human Lhcgr gene into a 170 kb BAC clone comprising the entire mouse orthologue. The methodology is based on the rationale to introduce a counter-selection cassette flanked by unique restriction sites and HAs for the insert, into the vector that is modified. Upon enzymatic digestion, in vitro or in Escherichia coli, double-strand breaks are generated leading to recombination between the vector and the insert. The procedure described here is thus an additional powerful tool for manipulating large and complex genomic fragments.

Use of hecate-chorionic gonadotropin beta conjugate in therapy of lutenizing hormone receptor expressing gonadal somatic cell tumors

Improvement of cancer treatment is a major challenge of medical research. Despite the immense efforts made in the improvement of diagnosis and treatment, cancer remains a major concern and cause of morbidity and mortality. Most of the modern anti-neoplastic therapies have severe side effects, and tumor cells often develop drug resistance. There is promise in the new generation of treatments (gene therapy, immunotherapy, vaccines, etc.) that are under development, but the efficacies and side effects of such therapies have so far been disappointing. Receptor-based therapies are not new, but many normal cells also present the same receptors reducing the specificity of such approaches. Several lytic peptides have been investigated because of they appear to kill cancer cells due to changes of their membrane potential. Thus, linking receptor-specific ligands to lytic peptides is expected to augment the specificity of targeting and decrease the toxicity of lytic peptides on normal cells. One such polypeptide is hecate (an analogue to the bee venom main component, melittin) that preferentially kills cancer cells at low doses. When this peptide is fused with the 81-95 amino acid fragment of chorionic gonadotropin-beta (CGbeta) subunit (hecate-CGbeta), it targets cells expressing luteinizing hormone receptor (LHR), even at very low doses, or when LHR is expressed at low level. Our recent data showed that this peptide conjugate is efficient in destroying LHR-positive cells in xenografts and more importantly in transgenic mouse models developing LHR-positive somatic cell tumors in gonads. The mechanism of action of hecate-CGbeta after binding to LHR is destruction of cell membranes resulting in rapid cell death by necrosis with minimal side effects. This review summarizes our findings on the action of this novel peptide and considers the future potential of this family of targeting peptides in the treatment of neoplasias.

Mixed chelate copper complex, Casiopeina IIgly, binds and degrades nucleic acids: a mechanism of cytotoxicity

Metal-containing drugs that interact with DNA have been designed and studied for their anticancer activity. In this study, the mixed chelate copper-based anticancer drugs, the casiopeinas, were found to bind to DNA and to degrade DNA and RNA in the presence of reducing agents (e.g. ascorbic acid). Casiopeinas binding to DNA is high affinity, with harsh wash conditions failing to remove the interaction. The reaction requires oxygen, probably involved in the generation of *OH radicals, which would be responsible for the strand breakage. The reaction was diminished by catalase, and was completely abolished by copper chelators (e.g. trientine, EDTA); however, superoxide dismutase (SOD) had no significant effect on casiopeina-mediated DNA degradation. Casiopeina IIgly (casIIgly) in the presence of ascorbate was capable of degrading RNA, plasmid and genomic DNA, and chromatin and intranuclear genetic material. Moreover, catalase and/or SOD partially protected cells, ascorbic acid enhanced and trientine, a copper chelator, abolished the cytotoxicity of casIIgly. The generation of 8-oxodG in cells exposed to casIIgly suggests that the generation of ROS is the major cause of the cytotoxicity observed and underlies the high toxicity and anticancer activity of these compounds.

A novel targeted therapy of Leydig and granulosa cell tumors through the luteinizing hormone receptor using a hecate-chorionic gonadotropin beta conjugate in transgenic mice

We investigated the antitumoral efficacy, endocrine consequences, and molecular mechanisms underlying cell death induced by the Hecate-chorionic gonadotropin (CG)beta conjugate, a fusion protein of a 23-amino acid lytic peptide Hecate with a 15-amino acid (81-95) fragment of the human CGbeta chain. Transgenic (TG) mice expressing the inhibin alpha-subunit promoter (inhalpha)/Simian Virus 40 T-antigen (Tag) transgene, developing luteinizing hormone (LH) receptor (R) expressing Leydig and granulosa cell tumors, and wild-type control littermates were treated either with vehicle, Hecate, or Hecate-CGbeta conjugate for 3 weeks. Hecate-CGbeta conjugate treatment reduced the testicular and ovarian tumor burden (P < .05), whereas a concomitant increase (testis; P < .05) or no change (ovary) in tumor volumes occured with Hectate treatment. A drop in serum progesterone, produced by the tumors, and an increase in LH levels occured in Hecate-CGbeta treated mice, in comparison with vehicle and Hecate groups, providing further support for the positive treatment response. Hecate-CGbeta conjugate induced a rapid and cell-specific membrane permeabilization of LHR-expressing cells in vitro, suggesting a necrotic mode of cell death without activation of apoptosis. These results prove the principle that the Hecate-CGbeta conjugate provides a novel specific lead into gonadal somatic cell cancer therapy by targeted destruction of LHR-expressing tumor cells.

Adrenocortical tumorigenesis in transgenic mice expressing the inhibin alpha-subunit promoter/simian virus 40 T-antigen transgene: relationship between ectopic expression of luteinizing hormone receptor and transcription factor GATA-4

We have analyzed the ontogeny and putative mechanisms of transregulation of LH receptor (LHR) and transcription factor GATA-4, coexpressed during the adrenocortical tumorigenesis of prepubertally gonadectomized transgenic (TG) mice expressing the inhibin alpha-subunit promoter/simian virus 40 T-antigen (inhalpha/Tag) transgene. The onset of adrenal LHR mRNA and protein expression coincided with that of GATA-4 at the age of 4 months and preceded the appearance of discernible adrenal tumors at about 6 months. In situ hybridization and double-immunohistochemistry demonstrated colocalization of the LHR and GATA-4 messages and proteins in the adrenal cortex. A GATA-4 expression plasmid cotransfected with a murine LHR promoter-driven luciferase reporter plasmid, containing a consensus GATA-binding site, induced a dose-dependent significant transactivation of the LHR promoter in nonsteroidogenic human embryonic kidney 293, steroidogenic murine mLTC-1 Leydig cells and in murine adrenal Y-1 cells. The Calpha1 cells derived from an Inhalpha/Tag adrenal tumor did not show this response, apparently due to their high endogenous GATA-4 expression. However, an additional link between GATA-4 and LHR in Calpha1 cells was provided upon the LH/human chorionic gonadotropin stimulation of LHR promoter activity; mutations or deletion of the consensus GATA-4 binding site of the LHR promoter abolished this transactivation. EMSAs further proved GATA-4 binding to the putative consensus GATA recognition site. Our results demonstrate direct interrelationship between LHR and GATA-4 expression during adrenocortical tumorigenesis of the inhalpha/Tag mice. There is apparently a positive and reciprocal feed-forward amplification link between LHR and GATA-4 expression. This mechanism gradually and in synergy with Tag expression leads to formation of the LH-dependent adrenocortical tumors.

Hematotoxicity response in rats by the novel copper-based anticancer agent: casiopeina II

The in vivo toxicity of the novel copper-based anticancer agent, casiopeina II (Cu(4,7-dimethyl-1,10-phenanthroline)(glycine)NO3) (CII), was investigated. Casiopeinas are a family of copper-coordinated complexes that have shown promising anticancer activity. The major toxic effect attributed to a single i.v. administration of CII (5 mg/kg dose) in the rat was an hemolytic anemia (reduced hemoglobin concentration (HB), red blood cell (RBC) count and packed cell volume (PCV) accompanied by a marked neutrophilic leukocytosis) 12 h and 5 days after administration, attributed to a direct erythrocyte damage. Increased reticulocyte levels and presence of normoblasts in peripheral blood 5 days post-administration indicated an effective erythropoietic response with recovery at 15 days. Increase in spleen weight and the morphological evidence of congestion of the red pulp (RP) with erythrocytes (E) resulting in a higher ratio of red to white pulp (WP) was consistent with increased uptake of damaged erythrocytes by the reticuloendothelial system observed by histopathology and electron microscopy. Extramedullary hemopoiesis was markedly increased at 5 days giving further evidence of a regenerative erythropoietic response that had an effective recovery by 15 days. Morphological changes in spleen cellularity were consistent with hematotoxicity, mainly a reduction of the red pulp/white pulp ratio, increase in erythrocyte content at 12 h, and an infiltration of nucleated cells in the red pulp at 5 days, with a tendency towards recovery 15 days after administration. The erythrocyte damage is attributed to generation of free radicals and oxidative damage on the membrane and within cells resulting from the reduction of Cu(II) and the probable dissociation of the CII complex.

Heat stress downregulates FLIP and sensitizes cells to Fas receptor-mediated apoptosis

The heat shock response and death receptor-mediated apoptosis are both key physiological determinants of cell survival. We found that exposure to a mild heat stress rapidly sensitized Jurkat and HeLa cells to Fas-mediated apoptosis. We further demonstrate that Hsp70 and the mitogen-activated protein kinases, critical molecules involved in both stress-associated and apoptotic responses, are not responsible for the sensitization. Instead, heat stress on its own induced downregulation of FLIP and promoted caspase-8 cleavage without triggering cell death, which might be the cause of the observed sensitization. Since caspase-9 and -3 were not cleaved after heat shock, caspase-8 seemed to be the initial caspase activated in the process. These findings could help understanding the regulation of death receptor signaling during stress, fever, or inflammation.