AXL receptor tyrosine kinase modulates gonadotropin-releasing hormone receptor signaling

BACKGROUND

Gonadotropin-releasing hormone (GnRH) receptors are essential for reproduction and are expressed in numerous urogenital, reproductive, and non-reproductive cancers. In addition to canonical G protein-coupled receptor signaling, GnRH receptors functionally interact with several receptor tyrosine kinases. AXL is a receptor tyrosine kinase expressed in numerous tissues as well as multiple tumors. Here we tested the hypothesis that AXL, along with its endogenous ligand Gas6, impacts GnRH receptor signaling.

METHODS

We used clonal murine pituitary αT3-1 and LβT2 gonadotrope cell lines to examine the effect of AXL activation on GnRH receptor-dependent signaling outcomes. ELISA and immunofluorescence were used to observe AXL and GnRH receptor expression in αT3-1 and LβT2 cells, as well as in murine and human pituitary sections. We also used ELISA to measure changes in ERK phosphorylation, pro-MMP9 production, and release of LHβ. Digital droplet PCR was used to measure the abundance of Egr-1 transcripts. A transwell migration assay was used to measure αT3-1 and LβT2 migration responses to GnRH and AXL.

RESULTS

We observed AXL, along with the GnRH receptor, expression in αT3-1 and LβT2 gonadotrope cell lines, as well as in murine and human pituitary sections. Consistent with a potentiating role of AXL, Gas6 enhanced GnRH-dependent ERK phosphorylation in αT3-1 and LβT2 cells. Further, and consistent with enhanced post-transcriptional GnRH receptor responses, we found that Gas6 increased the abundance of Egr-1 transcripts. Suggesting functional significance, in LβT2 cells, Gas6/AXL signaling stimulated LHβ production and enhanced GnRH receptor-dependent generation of pro-MMP9 protein and promoted cell migration.

CONCLUSIONS

Altogether, these data describe a novel role for AXL as a modulator of GnRH receptor signaling. Video Abstract.

Socioeconomic inequalities in metabolic syndrome and its components in a sample of Iranian Kurdish adults

OBJECTIVES

The worldwide incidence of metabolic syndrome (MetS) has increased in recent decades. In this study, we investigated the socioeconomic inequalities associated with MetS and its components in a sample of the Iranian Kurdish population.

METHODS

We used data from 3,996 participants, aged 35 years to 70 years, from the baseline phase of the Dehgolan Prospective Cohort Study (February 2018 to March 2019). The concentration index and concentration curve were used to measure inequality and the Blinder-Oaxaca decomposition method was used to examine the contribution of various determinants to the observed socioeconomic inequality in MetS and its components.

RESULTS

The prevalence of MetS was 34.44% (95% confidence interval [CI], 32.97 to 35.93). The prevalence of MetS was 26.18% for those in the highest socioeconomic status (SES), compared with 40.51% for participants in the lowest SES. There was a significant negative concentration index for MetS (C=-0.13; 95% CI, -0.16 to -0.09), indicating a concentration of MetS among participants with a lower SES. The most prevalent component was abdominal obesity (59.14%) with a significant negative concentration index (C=-0.21; 95% CI, -0.25 to -0.18). According to decomposition analysis, age, gender, and education were the highest contributing factors to inequality in MetS and its components.

CONCLUSIONS

This study showed socioeconomic inequality in MetS. People with a low SES were more likely to have MetS. Therefore, policymakers and health managers need to develop appropriate strategies to reduce these inequalities in MetS across age groups, genders, and education levels, especially among women and the elderly.

AXL/Gas6 signaling mechanisms in the hypothalamic-pituitary-gonadal axis

AXL is a receptor tyrosine kinase commonly associated with a variety of human cancers. Along with its ligand Gas6 (growth arrest-specific protein 6), AXL is emerging as an important regulator of neuroendocrine development and function. AXL signaling in response to Gas6 binding impacts neuroendocrine structure and function at the level of the brain, pituitary, and gonads. During development, AXL has been identified as an upstream inhibitor of gonadotropin receptor hormone (GnRH) production and also plays a key role in the migration of GnRH neurons from the olfactory placode to the forebrain. AXL is implicated in reproductive diseases including some forms of idiopathic hypogonadotropic hypogonadism and evidence suggests that AXL is required for normal spermatogenesis. Here, we highlight research describing AXL/Gas6 signaling mechanisms with a focus on the molecular pathways related to neuroendocrine function in health and disease. In doing so, we aim to present a concise account of known AXL/Gas6 signaling mechanisms to identify current knowledge gaps and inspire future research.

Corticotropin releasing hormone is present in the feline placenta and maternal serum

Background

In women, placental corticotropin releasing hormone (CRH) can be detected in maternal blood throughout pregnancy and is important in the regulation of the timing of parturition. However, its role in other mammalian species is unclear. In fact, very little is known about the presence and localization of CRH in placentas other than human. In this study we report for the first time the presence of CRH in feline placenta and maternal serum.

Methods

Presence of CRH mRNA and protein was assessed using RT-PCR and Western blot, respectively, in at term domestic cat placentas opportunistically obtained at a local animal shelter and spay clinic. In addition, CRH localization within the placenta was demonstrated via immunohistochemistry. Finally, presence of CRH in maternal blood from early (¾21 days) and mid (25-35 days) stages of pregnancy was investigated by ELISA.

Results

CRH mRNA and protein were detected in feline placentas, and localized to larger decidual cells and fetal trophoblast cells, including the binucleate cells. CRH was detectable in maternal blood collected from early-stage pregnancies, and amounts significantly increased in mid-gestation samples.

Conclusion

This is the first report on the presence and localization of CRH in the feline placenta, and its increase in maternal serum during the first half of pregnancy. These data lay the foundation for future studies to determine if CRH can be used as potential novel marker for early pregnancy diagnosis, determination, and monitoring in felids, and could greatly increase efficiency and success in zoo breeding programs utilizing artificial reproductive technologies for endangered feline species.

99mTc- Anionic dendrimer targeted vascular endothelial growth factor as a novel nano-radiotracer for in-vivo breast cancer imaging

Since breast cancer is the commonly cause of death among women around the world, diagnosis at the early stages is significantly important to prevent the metastasis of the cancer. Among the various growth factors that are involved in angiogenesis, vascular endothelial growth factor (VEGF) is believed to be the most important factor. Overexpressed VEGF receptor on tumors surface, is particularly interesting for cancer cells targeting purposes. In this study, citric acid dendrimer conjugated with VEGF antagonist peptide was synthesized. The obtained product was confirmed by FT-IR, TEM, DLS, and EDS. In vitro cytotoxicity assay showed no toxicity on normal cells and indicated the notably dose-dependence toxicity on cancer cells. Box-Behnken software as a computational method was used to determine the optimum amount of radiolabeling parameters. Optimized parameters for reducing agent, dendrimer-anti-VEGF, and time were 1.4 mg, 17.5 mg, and about 30 min respectively. Radiochemical purity of radio-labeled conjugated dendrimer was determined about 90 percent. SPECT imaging was done to observe the in vivo accumulation of dendrimer-anti-VEGF in the tumor site. Images showed high accumulation of radio-tracer in the tumor region. All in all, obtained results confirmed our hypothesis that the dendrimer-anti-VEGF can be a good radio-tracer for diagnosis of cancer.

Novel manganese carbon quantum dots as a nano-probe: Facile synthesis, characterization and their application in naproxen delivery (Mn/CQD/SiO2@naproxen)

This study for the first time pursues two crucial aims of using Naproxen as a non-steroidal anti-inflammatory drug in a better, non-invasive setting and introducing a simple and biocompatible nano-carrier (Mn/CQD/SiO₂) which is a magneto carbon quantum dots modified with mesoporous silica probe which can be served as a drug delivery and tracer system. SiO₂modification was doneby mesoporous silica which improves biocompatibility and provideslow cytotoxicity. Naproxen was conjugated to the nano-probe to form Mn/CQD/SiO₂@naproxen and biodistribution was investigated. Physicochemical characteristics of the Mn/CQD/SiO₂@naproxen were investigated using FT-IR, SEM, TEM, UV-Vis and BET. Antiproliferation assay using MTT assay was performed on HEK-293 cells to determine the cytotoxity of Mn/CQD/SiO₂@naproxen. Relaxivity of Mn/CQD/SiO2 was examined thereafter. To investigate the imaging capability of Mn/CQD/SiO₂@naproxen and biodistribution of Naproxen, fluorescent imaging was done. To confirm the data, then the levels of COX Gene expression was determined. The specific surface area, pore volume, and pore radius were 44.4 m²/g, 10.23 cm³/g, and 25.9 nm respectively. MTT assay showed no cytotoxicity. Relaxivity of Mn/CQD/SiO₂ was higher than conventional Gd-based contrast agent. Fluorescence imaging of Mn/CQD/SiO₂@naproxen showed the biodistribution of naproxen. COX Gene expression confirmed the biodistribution data. By increasing the accumulation in liver COX production reduced. All in all, unique features of Mn/CQD/SiO₂ including biocompatibility, low toxicity, magnetic and fluorescence properties showed that it can be used in biomedical sciences.

PEG-Citrate dendrimer second generation: is this a good carrier for imaging agents In Vitro and In Vivo?

While cancer is the leading cause of human's deaths worldwide, finding an imaging agent which can detect cancer tumours is needed for cancer diagnosis. In the present study, PEG-citrate dendrimer-G2 was used as a nano-carrier of FITC dye and Iohexol to help passive targeting and uptake of both imaging agents in cancer cells/tumour in vitro and in vivo. Dendrimer was synthesisedand the product characterised using LC-MS, FT-IR, DLS, ELS, AFM, and 1HNMR. After FITC loading into dendrimer, MTT was performed to determine the cytotoxicity of formulation on HEK-293 and MCF-7 cells. In vitro imaging using dendrimer-FITC was done via fluorescent microscope thereafter. Moreover, CT imaging using Iohexol was employed to show the targeting nature and ability of the complex to use as imaging agent in vivo. Data yielded in this study corroborate the notion that the promised dendrimer was synthesised properly and had no toxicity along with FITC on normal cell. Furthermore, CT and fluorescent images showed the targeting nature and imaging ability of Iohexol/FITC loaded dendrimer in vitro and in vivo. Overall, results showed promising characteristics of the novel complexes using dendrimer-G2 both in vitro and in vivo.

Technetium-99m chelator-free radiolabeling of specific glutamine tumor imaging nanoprobe: in vitro and in vivo evaluations

Introduction

Nowadays, molecular imaging radiopharmaceuticals', nanoparticles', and/or small-molecule biomarkers' applications are increasing rapidly worldwide. Thus, researchers focus on providing the novel, safe, and cost-effective ones.

Materials and methods

In the present experiment, technetium-99m (^99mTc)-labeled PEG-citrate dendrimer-G₂ conjugated with glutamine (nanoconjugate) was designed and assessed as a novel tumor imaging probe both in vitro and in vivo. Nanoconjugate was synthesized and the synthesis was confirmed by Fourier transform infrared, proton nuclear magnetic resonance, liquid chromatography-mass spectrometry, dynamic light scattering, and static light scattering techniques. The toxicity was assessed by XTT and apoptosis and necrosis methods.

Results

Radiochemical purity indicates that the anionic dendrimer has a very high potential to complex formation with ^99mTc and is also very stable in the human serum in different times. Results from the imaging procedures showed potential ability of nanoconjugates to detect tumor site.

Conclusion

Suitable features of the anionic dendrimer show that it is a promising agent to improve nanoradiopharmaceuticals.

AS1411 Aptamer-Anionic Linear Globular Dendrimer G2-Iohexol Selective Nano-Theranostics

Molecular theranostics is of the utmost interest for diagnosis as well as treatment of different malignancies. In the present study, anionic linear globular dendrimer G2 is employed as a suitable carrier for delivery and AS1411 aptamer is exploited as the targeting agent to carry Iohexol specifically to the human breast cancer cells (MCF-7). Dendrimer G2 was prepared and conjugation of dendrimer and aptamer was carried out thereafter. Based on the data yielded by AFM, morphology of smooth and spherical non-targeted dendrimer changed to the rough aspherical shape when it conjugated. Then, conjugation was confirmed using DLS, ELS and SLS methods. Toxicity on nucleolin positive MCF-7 cells and nucleolin negative HEK-293 cells was assessed by XTT and apoptosis/necrosis assays. In vitro uptake was determined using DAPI-FITC staining and ICP-MS methods. In vivo studies including in vivo CT imaging, pathology and blood tests were done to confirm the imaging ability, bio-safety and targeted nature of the Nano-Theranostics in vivo. In a nutshell, the prepared construction showed promising effects upon decreasing the toxicity of Iohexol on normal cells and accumulation of it in the cancer tumors as well as reducing the number of cancer cells.