Opioid Growth Factor Research Articles

Targeting OGF/OGFR signal to mitigate doxorubicin-induced cardiotoxicity

Enkephalins are reportedly correlated with heart function. However, their regulation in the heart remains unexplored. This study revealed a substantial increase in circulating levels of opioid growth factor (OGF) (also known as methionine enkephalin) and myocardial expression levels of both OGF and its receptor (OGFR) in subjects treated with doxorubicin (Dox). Silencing OGFR through gene knockout or using adeno-associated virus serotype 9 carrying small hairpin RNA effectively alleviated Dox-induced cardiotoxicity (DIC) in mice. Conversely, OGF supplementation exacerbated DIC manifestations, which could be abolished by administration of the OGFR antagonist naltrexone (NTX). Mechanistically, the previously characterized OGF/OGFR/P21 axis was identified to facilitate DIC-related cardiomyocyte apoptosis. Additionally, OGFR was observed to dissociate STAT1 from the promoters of ferritin genes (FTH and FTL), thereby repressing their transcription and exacerbating DIC-related cardiomyocyte ferroptosis. To circumvent the compromised therapeutic effects of Dox on tumors owing to OGFR blockade, SiO2-based modifiable lipid nanoparticles were developed for heart-targeted delivery of NTX. The pretreatment of tumor-bearing mice with the assembled NTX nanodrug successfully provided cardioprotection against Dox toxicity without affecting Dox therapy in tumors. Taken together, this study provides a novel understanding of Dox cardiotoxicity and sheds light on the development of cardioprotectants for patients with tumors receiving Dox treatment.

Topical naltrexone increases aquaporin 5 production in the lacrimal gland and restores tear production in diabetic rats.

Diabetes mellitus is a prevalent disease that is often accompanied by ocular surface abnormalities including delayed epithelial wound healing and decreased corneal sensitivity. The impact of diabetes on the lacrimal functional unit (LFU) and the structures responsible for maintaining tear homeostasis, is not completely known. It has been shown that the Opioid Growth Factor Receptor (OGFr), and its ligand, Opioid Growth Factor (OGF), is dysregulated in the ocular surface of diabetic rats leading to overproduction of the inhibitory growth peptide OGF. The opioid antagonist naltrexone hydrochloride (NTX) blocks the OGF-OGFr pathway, and complete blockade following systemic or topical treatment with NTX restores the rate of re-epithelialization of corneal epithelial wounds, normalizes corneal sensitivity, and reverses dry eye in diabetic animal models. These effects occur rapidly and within days of initiating treatment. The present study was designed to understand mechanisms related to the fast reversal (<5 days) of dry eye by NTX in type 1 diabetes (T1D) by investigating dysregulation of the LFU. The approach involved examination of the morphology of the LFU before and after NTX treatment. Male and female adult Sprague-Dawley rats were rendered hyperglycemic with streptozotocin, and after 6 weeks rats were considered to be a T1D model. Rats received topical NTX twice daily to one eye for 10 days. During the period of treatment, tear production and corneal sensitivity were recorded. On day 11, animals were euthanized and orbital tissues including conjunctiva, eyelids, and lacrimal glands, were removed and processed for histologic examination including immunohistochemistry. Male and female T1D rats had significantly decreased tear production and corneal insensitivity, significantly decreased number and size of lacrimal gland acini, decreased expression of aquaporin-5 (AQP5) protein and decreased goblet cell size. Thus, 10 days of NTX treatment restored tear production and corneal sensitivity to normal values, increased AQP5 expression, and restored the surface area of goblet cells to normal. NTX had no effect on the number of lacrimal gland acini or the number of conjunctival goblet cells. In summary, blockade of the OGF-OGFr pathway with NTX reversed corneal and lacrimal gland complications and restored some components of tear homeostasis confirming the efficacy of topical NTX as a treatment for ocular defects in diabetes.

Loss-of-function OGFRL1 variants identified in autosomal recessive cherubism families.

Cherubism (OMIM 118400) is a rare craniofacial disorder in children characterized by destructive jawbone expansion due to the growth of inflammatory fibrous lesions. Our previous studies have shown that gain-of-function mutations in SH3 domain-binding protein 2 (SH3BP2) are responsible for cherubism and that a knock-in mouse model for cherubism recapitulates the features of cherubism, such as increased osteoclast formation and jawbone destruction. To date, SH3BP2 is the only gene identified to be responsible for cherubism. Since not all patients clinically diagnosed with cherubism had mutations in SH3BP2, we hypothesized that there may be novel cherubism genes and that these genes may play a role in jawbone homeostasis. Here, using whole exome sequencing, we identified homozygous loss-of-function variants in the opioid growth factor receptor like 1 (OGFRL1) gene in 2 independent autosomal recessive cherubism families from Syria and India. The newly identified pathogenic homozygous variants were not reported in any variant databases, suggesting that OGFRL1 is a novel gene responsible for cherubism. Single cell analysis of mouse jawbone tissue revealed that Ogfrl1 is highly expressed in myeloid lineage cells. We generated OGFRL1 knockout mice and mice carrying the Syrian frameshift mutation to understand the in vivo role of OGFRL1. However, neither mouse model recapitulated human cherubism or the phenotypes exhibited by SH3BP2 cherubism mice under physiological and periodontitis conditions. Unlike bone marrow-derived M-CSF-dependent macrophages (BMMs) carrying the SH3BP2 cherubism mutation, BMMs lacking OGFRL1 or carrying the Syrian mutation showed no difference in TNF-ɑ mRNA induction by LPS or TNF-ɑ compared to WT BMMs. Osteoclast formation induced by RANKL was also comparable. These results suggest that the loss-of-function effects of OGFRL1 in humans differ from those in mice and highlight the fact that mice are not always an ideal model for studying rare craniofacial bone disorders.

Low-Dose Naltrexone as an Adjuvant in Combined Anticancer Therapy.

Naltrexone (NTX) is a non-selective antagonist of opioid receptors, primarily used in the therapy of opioid and alcohol dependence. Low-dose naltrexone (LDN) exhibits antagonistic action against the opioid growth factor receptor (OGFr), whose signaling is associated with the survival, proliferation, and invasion of cancer cells. The mechanism of action of LDN depends on the dose and duration of the OGFr blockade, leading to a compensatory increase in the synthesis of the opioid growth factor (OGF), which has an inhibitory effect on carcinogenesis. Numerous studies on in vitro and in vivo models provide evidence of LDN's positive impact on inhibiting the OGF-OGFr axis in cancers. LDN's unique mechanism of action on cancer cells, lack of direct cytotoxic effect, and immunomodulating action form the basis for its use as an adjuvant in chemotherapy and immunotherapy of cancerous lesions.

Design, Synthesis, and Antitumor Evaluation of an Opioid Growth Factor Bioconjugate Targeting Pancreatic Ductal Adenocarcinoma.

Pancreatic ductal adenocarcinoma (PDAC) presents a formidable challenge with high lethality and limited effective drug treatments. Its heightened metastatic potential further complicates the prognosis. Owing to the significant toxicity of current chemotherapeutics, compounds like [Met5]-enkephalin, known as opioid growth factor (OGF), have emerged in oncology clinical trials. OGF, an endogenous peptide interacting with the OGF receptor (OGFr), plays a crucial role in inhibiting cell proliferation across various cancer types. This in vitro study explores the potential anticancer efficacy of a newly synthesized OGF bioconjugate in synergy with the classic chemotherapeutic agent, gemcitabine (OGF-Gem). The study delves into assessing the impact of the OGF-Gem conjugate on cell proliferation inhibition, cell cycle regulation, the induction of cellular senescence, and apoptosis. Furthermore, the antimetastatic potential of the OGF-Gem conjugate was demonstrated through evaluations using blood platelets and AsPC-1 cells with a light aggregometer. In summary, this article demonstrates the cytotoxic impact of the innovative OGF-Gem conjugate on pancreatic cancer cells in both 2D and 3D models. We highlight the potential of both the OGF-Gem conjugate and OGF alone in effectively inhibiting the ex vivo pancreatic tumor cell-induced platelet aggregation (TCIPA) process, a phenomenon not observed with Gem alone. Furthermore, the confirmed hemocompatibility of OGF-Gem with platelets reinforces its promising potential. We anticipate that this conjugation strategy will open avenues for the development of potent anticancer agents.

Biology of the Opioid Growth Factor – Opioid Growth Factor Receptor Axis: Bench to Bedside and Back

The Opioid Growth Factor – Opioid Growth Factor Receptor axis was identified nearly 30 years ago in our laboratory when we demonstrated that an endogenous opioid pentapeptide had inhibitory growth activity following injection into normal animals. In addition to validating this action for the peptide, identification, characterization and cloning of the specific receptor related to the opioid growth factor, chemically termed [Met5]-enkephalin, revealed that the receptor was unique in its biochemical and molecular structure, but had pharmacological properties similar to other opioid receptors. Mechanisms associated with binding of the opioid growth factor to its receptor located on the outer nuclear envelop and the transport into the nucleus were identified. The selectively of the peptide for the receptor was demonstrated in normal and cancer cell lines. This uniqueness of the peptide-receptor interaction was evidenced by the duration of receptor blockade in that intermittent blockade resulted in decreased cell replication and complete blockade resulted in accelerated proliferation. Investigations on the mechanism of action, as well as the dysregulation of the Opioid Growth Factor – Opioid Growth Factor Receptor axis in human pathology, have resulted in bench to bedside and bedside to bench discoveries. Receptor blockade by naltrexone has been used clinically for treatment of fatigue and other immune deficiencies in many autoimmune disorders. The research has gone from bench to bedside and has returned to the bench for additional investigation of mechanisms driving the action of the axis and resultant function following receptor blockade.

Current pharmacotherapeutic properties of low-dose naltrexone therapy in humans and possible therapeutic and prophylactic indications in cats and dogs

Naltrexone was first developed in 1963 as an opioid antagonist for therapeutic use in opioid-dependent individuals (alcohol, narcotics, and tobacco) with a 50 mg/day dose approved by the Food and Drug Administration (FDA). In 1985, Dr. Bernard Bihari explained that when naltrexone is taken in very low doses (1-5 mg/day) before bedtime, it blocks opioid receptors for 2- 4 hours and leads to the release of endorphins in the early morning hours, serving as an opioid agonist and immunomodulatory agent. This extra endorphin secretion has been proven to enhance the immune system response in AIDS patients. Endogenous opioids that affect cell development are referred to as opioid growth factor (OGF) and met-enkephalin (ME). Low-dose-naltrexone (LDN) pharmacotherapeutically possesses immunomodulatory, anticarcinogenic, antiviral, antibacterial, antiparasitic, and antifungal properties. LDN also increases the production and sensitivity of OGF, ME, and OGF receptor (OGFr) in the bloodstream, thereby enhancing quality of life. Based on these pharmacotherapeutic properties, LDN application is believed to be effective in the treatment or prophylaxis of various infectious diseases in cats and dogs, particularly vasculitis-related diseases such as feline infectious peritonitis (FIP) and infectious canine hepatitis (ICH), hypothyroidism, gastrointestinal disorders, spondylosis, rheumatoid arthritis, autoimmune diseases, pneumonia, atopic and allergic dermatitis, pyodermas, resistant pyodermas, methicillin-resistant Staphylococcus aureus (MRSA) or various gastrointestinal disorders, alopecia, stubborn dermatomycosis, stubborn demodicosis, various geriatric and oncogenic diseases, and deep depressions or obsessive-compulsive disorders. Thus, this review aims to evaluate the pharmacotherapeutic properties of LDN therapy usage and mechanisms of action in detail and assess the potential indications in cats and dogs based on these mechanisms.

The opioid growth regulatory system and naltrexone in diabetes: One side makes you taller and the other side makes you smaller

This article provides an overview of research into the inhibitory role of the Opioid Growth Regulatory System (OGRS), which is characterized by its mediator, Opioid Growth Factor (OGF), [Met 5 ]-enkephalin, and its specific receptor (OGFr), in the pathobiology of diabetic complications involving the ocular surface. Additionally, involvement of the OGRS in systemic diabetic complications is illustrated by its role in poor diabetic cutaneous wound healing. The title of this paper is derived from Lewis Carroll’s Alice’s Adventures in Wonderland in which Alice is invited by the caterpillar to eat either side of a mushroom with powerful growth inducing characteristics. In the context of this review, this metaphor highlights the antagonistic relationship between the OGRS and naltrexone (NTX), which blocks the binding of OGF to OGFr thereby preventing or reversing the deleterious effects of the OGRS in the pathobiology of diabetic complications such as dry eye, keratopathy (delayed corneal epithelial wound healing and decreased corneal sensitivity) and delayed cutaneous wound healing in animal models of type 1 and type 2 diabetes. In addition, we will show that topical NTX treatment has been demonstrated to be safe in early phase studies performed in humans. We believe these data support further clinical trials of NTX in the treatment of diabetic ocular surface disease and delayed cutaneous wound healing. Finally, our findings may have implications for the evaluation of the OGRS in the pathobiology of other systemic diabetic complications.

Morphine Analgesia, Cannabinoid Receptor 2, and Opioid Growth Factor Receptor Cancer Tissue Expression Improve Survival after Pancreatic Cancer Surgery.

Pancreatic cancer (PDAC) has a poor prognosis despite surgical removal and adjuvant therapy. Additionally, the effects of postoperative analgesia with morphine and piritramide on survival among PDAC patients are unknown, as are their interactions with opioid/cannabinoid receptor gene expressions in PDAC tissue. Cancer-specific survival data for 71 PDAC patients who underwent radical surgery followed by postoperative analgesia with morphine (n = 48) or piritramide (n = 23) were therefore analyzed in conjunction with opioid/cannabinoid receptor gene expressions in the patients' tumors. Receptor gene expressions were determined using the quantitative real-time polymerase chain reaction. Patients receiving morphine had significantly longer cancer-specific survival (CSS) than those receiving piritramide postoperative analgesia (median 22.4 vs. 15 months; p = 0.038). This finding was supported by multivariate modelling (p < 0.001). The morphine and piritramide groups had similar morphine equipotent doses, receptor expression, and baseline characteristics. The opioid/cannabinoid receptor gene expression was analyzed in a group of 130 pancreatic cancer patients. Of the studied receptors, high cannabinoid receptor 2 (CB2) and opioid growth factor receptor (OGFR) gene expressions have a positive influence on the length of overall survival (OS; p = 0.029, resp. p = 0.01). Conversely, high delta opioid receptor gene expression shortened OS (p = 0.043). Multivariate modelling indicated that high CB2 and OGFR expression improved OS (HR = 0.538, p = 0.011, resp. HR = 0.435, p = 0.001), while high OPRD receptor expression shortened OS (HR = 2.264, p = 0.002). Morphine analgesia, CB2, and OGFR cancer tissue gene expression thus improved CSS resp. OS after radical PDAC surgery, whereas delta opioid receptor expression shortened OS.

Elevated Opioid Growth Factor Alters the Limbus in Type 1 Diabetic Rats.

Ocular surface complications occur in more than 50% of individuals diagnosed with diabetes. The financial and health-related burden of diabetes is increasing annually. Several major ocular complications associated with diabetes involve the limbus. The vascular limbus, adjacent to the avascular cornea, is the source of circulating growth factors, elevated glucose, and cytokines for the cornea. The Opioid Growth Factor (OGF) - Opioid OGF Receptor (OGFr) axis is comprised of its effector peptide, OGF, [Met5]-enkephalin and the nuclear-associated receptor, OGFr, and has been demonstrated to be dysfunctional in diabetes with elevated serum and tissue levels of the inhibitory growth factor OGF recorded in corneal tissue. Little is known regarding the impact of OGF-OGFr axis dysregulation in diabetes on the functioning of the limbus constituents in support of corneal homeostasis. Adult male and female Sprague-Dawley rats were rendered hyperglycemic through intraperitoneal injections of streptozotocin (T1D); a subset of T1D rats received topical naltrexone (NTX) applied to the cornea and limbus daily for 8 weeks. At 4 and/or 8 weeks of hyperglycemia, different cohorts of animals were euthanized, eyes removed and processed for assessment of limbal morphology, expression of OGF, OGFr, cytokeratin 15, a marker for limbal cells, and Ki-67, a marker of proliferation. Limbal epithelial morphology (cell diameter, packing density) was altered in T1D male and female rats. OGF and OGFr were overexpressed in the limbus and CK15 expression was decreased, relative to normal control rats of the same sex. Blockade of the OGF- OGFr axis with NTX reversed limbal epithelial cell defects, and reduced OGF limbal tissue levels to those recorded in non-diabetic rats. In summary, OGF-OGFr axis dysregulation was observed in the limbus of T1D rats, contributing to the altered limbal morphology and delayed corneal surface healing observed in diabetic animals.

Acute Low Dose Naltrexone Increases β-Endorphin and Promotes Neuronal Recovery Following Hypoxia-Ischemic Stroke in Type-2 Diabetic Mice.

Diabetic patients experience significant mortality and poor recovery following ischemic stroke. Our clinical and basic science studies demonstrate an overall immune suppression in the periphery of diabetic stroke patients, as well as within the central nervous system (CNS) of type-2 diabetic mice following hypoxia-ischemia (HI). Low doses of naltrexone (LDN) improved clinical outcomes in many autoimmune diseases by acting on opioid receptors to release β-endorphin which in turn balances inflammatory cytokines and modulates the opioid growth factor (OGF)-opioid growth factor receptor (OGFr) pathway. We hypothesized that in our model of diabetic mice, LDN treatment will induce the release of β-endorphin and improve CNS response by promoting neuronal recovery post HI. To test this hypothesis, we induced HI in 10week old male db/db and db/ + mice, collected tissue at 24 and 72h post HI, and measured OGF levels in plasma and brain tissue. The infarct size and number of OGF + neurons in the motor cortex, caudate and hippocampus (CA3) were measured. Following HI, db/db mice had significant increases in brain OGF expression, increased infarct size and neurological deficits, and loss of OGFr + neurons in several different brain regions. In the second experiment, we injected LDN (1mg/kg) intraperitoneally into db/db and db/ + mice at 4, 24, and 48h post HI, and collected brain tissue and blood at 72h. Acute LDN treatment increased β-endorphin and OGF levels in plasma and promoted neuronal recovery in db/db mice compared to phosphate buffer saline (PBS)-treated diabetic mice suggesting a protective or regenerative effect of LDN.

Opioid growth factor receptor promotes adipose tissue thermogenesis via enhancing lipid oxidation

Abstract The thermogenic brown and beige adipocytes consume fatty acids and generate heat to maintain core body temperature in the face of cold challenges. Since their validated presence in humans, the activation of thermogenic fat has been an attractive target for treating obesity and related metabolic diseases. Here, we reported that the opioid growth factor receptor (Ogfr) was highly expressed in adipocytes and promoted thermogenesis. The mice with genetic deletion of Ogfr in adipocytes displayed an impaired capacity to counter environmental cold challenges. Meanwhile, Ogfr ablation in adipocytes led to reduced fatty acid oxidation, enhanced lipid accumulation, impaired glucose tolerance, and exacerbated tissue inflammation under chronic high-fat diet (HFD)-fed conditions. At the cellular level, OGFr enhanced the production of mitochondrial trifunctional protein subunit α (MTPα) and also interacted with MTPα, thus promoting fatty acid oxidation. Together, our study demonstrated the important role of OGFr in fatty acid metabolism and adipose thermogenesis.

Methionine enkephalin suppresses lung cancer metastasis by regulating the polarization of tumor-associated macrophages and the distribution of myeloid-derived suppressor cells in the tumor microenvironment and inhibiting epithelial-mesenchymal transition

Metastasis is one of the most difficult challenges for clinical lung cancer treatment. Epithelial-mesenchymal transition (EMT) is the crucial step of tumor metastasis. Immune cells in the tumor microenvironment (TME), such as tumor-associated macrophages (TAMs) and myeloid-derived suppressor cells (MDSCs), promote cancer cell EMT. In this study, we explored the effect of methionine enkephalin (MENK) on the EMT process in vitro and in vivo, and its influence on TAMs, MDSCs, and associated cytokines in vivo. The results showed that MENK suppressed growth, migration, and invasion of lung cancer cells and inhibited the EMT process by interacting with opioid growth factor receptor. MENK reduced the number of M2 macrophages and MDSC infiltration, and downregulated the expression of interleukin-10 and transforming growth factor-β1 in both primary and metastatic tumors of nude mice. The present findings suggest that MENK is a potential target for suppressing metastasis in lung cancer treatment.

Opioid growth factor receptor: Anatomical distribution and receptor colocalization in neurons of the adult mouse brain

The opioid growth factor (OGF) is an endogenous peptide that binds to the nuclear-associated receptor (OGFr), and plays a significant role in the proliferation of developing, renewing, and healing tissues. The receptor is widely expressed in a variety of organs, however its distribution in the brain remains unknown. In this study, we investigated the distribution of OGFr in different brain regions of male heterozygous (-/+ Lepr db/J), non -diabetic mice and determined the localization of the receptor in three major brain cell types, astrocytes, microglia, and neurons. Immunofluorescence imaging revealed that the highest number of OGFr was in hippocampal CA3 subregion followed by primary motor cortex, hippocampal CA2, thalamus, caudate and hypothalamus in a descending order. Double immunostaining revealed receptor colocalization with neurons and little or no colocalization in microglia and astrocytes. The highest percentage of OGFr positive neurons was identified in the CA3. Hippocampal CA3 neurons play an important role in memory processing, learning and behavior, and motor cortex neurons are important for muscle movement. However, the significance of the OGFr receptor in these brain regions and its relevance in diseased conditions are not known. Our findings provide a basis for understanding the cellular target and interaction of the OGF- OGFr pathway in neurodegenerative diseases such as Alzheimer's, Parkinson's, and stroke where hippocampus and cortex have an important role. This foundational data may also be useful in drug discovery to modulate OGFr by opioid receptor antagonist in various CNS diseases.

Long non-coding RNA OGFRP1 regulates cell proliferation and ferroptosis by miR-299-3p/SLC38A1 axis in lung cancer.

Lung cancer is devastating cancer that ranks as the leading cause of cancer-related death. Long noncoding RNA (lncRNA) opioid growth factor receptor pseudogene 1 (OGFRP1) was recognized as an oncogene in many cancers. However, the molecular mechanism of OGFRP1 in lung cancer is still poorly understood. The expression of target RNAs and genes was detected by quantitative real-time PCR and western blot. The interaction between miR-299-3p and OGFRP1 or solute carrier family 38 member 1 (SLC38A1) was predicted by StarbaseV3.0 and verified by dual-luciferase reporter assay and Pearson's correlation coefficient. Besides, a transplantation model of human lung cancer in nude mice was established to evaluate the role of OGFRP1 in lung cancer. OGFRP1 and SLC38A1 were overexpressed, whereas miR-299-3p was lowly expressed in lung cancer tumors and cells. OGFRP1 knockdown suppressed cell proliferation and facilitated ferroptosis by promoting lipid peroxidation and iron accumulation in lung cancer. Besides, Furthermore, miR-299-3p inhibitor or SLC38A1 overexpression attenuated OGFRP1 depletion-induced suppression on cell proliferation and ferroptosis in lung cancer. Animal experiments indicated that OGFRP1 deficiency restrained tumor growth in vivo by regulating the miR-299-3p/SLC38A1 axis. OGFRP1 regulated cell proliferation and ferroptosis in lung cancer by inhibiting miR-299-3p to enhance SLC38A1 expression, providing a novel therapeutic strategy for lung cancer.

Opioid Receptor Expression in Colorectal Cancer: A Nested Matched Case-Control Study.

BackgroundThere is growing interest in the possible effect of perioperative anesthetic management on the growth and spread of cancer. The impact of perioperative use of opioids on cancer recurrence remains controversial and an assessment cannot yet be established based on current publications. This study aimed to assess the differential expression of opioid receptors between healthy and tumor tissues in patients with stage II and III colorectal cancer undergoing elective surgery by immunohistochemistry (IHC).MethodsPropensity–score matched case–control study nested in a retrospective cohort of patients with stage II or III colorectal. The primary endpoint was the difference in µ–opioid receptor (MOR) expression measured by IHC between tumor and healthy tissue in subject with or without recurrence. Secondary endpoints were to evaluate the differences in Opioid Growth Factor Receptor (OGFR), cyclic adenosine monophosphate (cAMP) production and protein kinase A (PKA) in the matched sample and from a from samples of colorectal cancer stored in the Cancer Genome Atlas (TCGA) and Genotype Tissue Expression Project (GTEx).ResultsThere was a significant difference in MOR receptor (median 3 [intequartile range IQR: 1–3] and 0 [IQR: 0–2], P<0.001) and OGFR receptor (median 6 [IQR: 5–6] and 2 [IQR: 1–2], P<0.001) in tumor and control tissue respectively. However, there were no significant differences in cAMP nor PKA expression between both types of tissues and in expression in any of the analyzed variables by recurrence status. The MOR and OGFR expression data from TCGA database were similar to our sample size data with lower expression of MOR and higher expression of OGFR in tumoural samples with a skewed distribution for MOR expression in tumor tissue both in patients with and without recurrence.ConclusionIn patients with stage II and III colorectal cancer, overall expression of MOR and OGFR was significantly increased but was not different between previously matched patients with or without recurrence. No differences were found in the analyzed metabolic pathway of cAMP–PKA: These results were confirmed by an in silico analysis of samples from the TCGA–GTEx database.

Solid Tumor Opioid Receptor Expression and Oncologic Outcomes: Analysis of the Cancer Genome Atlas and Genotype Tissue Expression Project.

BackgroundOpioid receptors are expressed not only by neural cells in the central nervous system, but also by many solid tumor cancer cells. Whether perioperative opioids given for analgesia after tumor resection surgery might inadvertently activate tumor cells, promoting recurrence or metastasis, remains controversial. We analysed large public gene repositories of solid tumors to investigate differences in opioid receptor expression between normal and tumor tissues and their association with long–term oncologic outcomes.MethodsWe investigated the normalized gene expression of µ, κ, δ opioid receptors (MOR, KOR, DOR), Opioid Growth Factor (OGFR), and Toll-Like 4 (TLR4) receptors in normal and tumor samples from twelve solid tumor types. We carried out mixed multivariable logistic and Cox regression analysis on whether there was an association between these receptors’ gene expression and the tissue where found, i.e., tumor or normal tissue. We also evaluated the association between tumor opioid receptor gene expression and patient disease–free interval (DFI) and overall survival (OS).ResultsWe retrieved 8,780 tissue samples, 5,852 from tumor and 2,928 from normal tissue, of which 2,252 were from the Genotype Tissue Expression Project (GTEx) and 672 from the Cancer Genome Atlas (TCGA) repository. The Odds Ratio (OR) [95%CI] for gene expression of the specific opioid receptors in the examined tumors varied: MOR: 0.74 [0.63–0.87], KOR: 1.27 [1.17–1.37], DOR: 1.66 [1.48–1.87], TLR4: 0.29 [0.26–0.32], OGFR: 2.39 [2.05–2.78]. After controlling all confounding variables, including age and cancer stage, there was no association between tumor opioid receptor expression and long–term oncologic outcomes.ConclusionOpioid receptor gene expression varies between different solid tumor types. There was no association between tumor opioid receptor expression and recurrence. Understanding the significance of opioid receptor expression on tumor cells remains elusive.

Acute Developmental Toxicity of Panax notoginseng in Zebrafish Larvae.

To evaluate toxicity of raw extract of Panax notoginseng (rPN) and decocted extract of PN (dPN) by a toxicological assay using zebrafish larvae, and explore the mechanism by RNA sequencing assay. Zebrafish larvae was used to evaluate acute toxicity of PN in two forms: rPN and dPN. Three doses (0.5, 1.5, and 5.0 µ g/mL) of dPN were used to treat zebrafishes for evaluating the developmental toxicity. Behavior abnormalities, body weight, body length and number of vertebral roots were used as specific phenotypic endpoints. RNA sequencing (RNA-seq) assay was applied to clarify the mechanism of acute toxicity, followed by real time PCR (qPCR) for verification. High performance liquid chromatography analysis was performed to determine the chemoprofile of this herb. The acute toxicity result showed that rPN exerted higher acute toxicity than dPN in inducing death of larval zebrafishes (P<0.01). After daily oral intake for 21 days, dPN at doses of 0.5, 1.5 and 5.0 µ g/mL decreased the body weight, body length, and vertebral number of larval zebrafishes, indicating developmental toxicity of dPN. No other adverse outcome was observed during the experimental period. RNA-seq data revealed 38 genes differentially expressed in dPN-treated zebrafishes, of which carboxypeptidase A1 (cpa1) and opioid growth factor receptor-like 2 (ogfrl2) were identified as functional genes in regulating body development of zebrafishes. qPCR data showed that dPN significantly down-regulated the mRNA expressions of cpa1 and ogfrl2 (both P<0.01), verifying cpa1 and ogfrl2 as target genes for dPN. This report uncovers the developmental toxicity of dPN, suggesting potential risk of its clinical application in children.

LncRNA OGFRP1 promotes cell proliferation and suppresses cell radiosensitivity in gastric cancer by targeting the miR-149-5p/MAP3K3 axis.

Gastric cancer (GC) is an aggressive malignancy with high incidence and mortality. Radiotherapy is a common treatment for patients with advanced GC. Many long noncoding RNAs (lncRNAs) have been verified to affect the radiosensitivity of multiple cancers in previous studies. Nevertheless, whether lncRNA opioid growth factor receptor pseudogene 1 (OGFRP1) affects the radiosensitivity of GC has not been determined. We hypothesized that OGFRP1 might affect cellular processes in GC development. The present study aims to explore the role of OGFRP1 in GC development. First, high expression of OGFRP1 in GC tissues and cells was determined through RT-qPCR. Subsequently, functional assays including colony formation assays, 5-Ethynyl-2'-deoxyuridine assays and flow cytometry analyses were performed to probe the biological functions of OGFRP1 in GC. Specifically, the effect of OGFRP1 on the radiosensitivity of GC cells was detected. Subsequently, with the help of the starBase tool, we found that miR-149-5p might bind to OGFRP1, which was confirmed through a luciferase reporter assay. Furthermore, we identified that MAP3K3 was targeted by miR-149-5p in GC cells. Finally, the results from rescue experiments validated that enhanced MAP3K3 expression counteracted the effect of OGFRP1 silencing on GC cell proliferation, apoptosis and radiosensitivity. Overall, OGFRP1 was determined to promote GC cell proliferation while suppressing cell apoptosis and radiosensitivity by regulating the miR-149-5p/MAP3K3 axis.

Sex Differences in Diabetic Ocular Surface Complications and Dysregulation of the OGF-OGFr Pathway.

Background:Diabetes is a chronic disorder that affects more than 500 million individuals worldwide. It is a life-long disease with complications that attack nearly all other systems within the body. Although there is a slight increase in the prevalence of diabetes in males, ocular surface complications are equally present in males and females.Aim:This review provides a discussion on preclinical studies related to the dysregulation of a biological pathway that appears to be causally related to diabetic ocular surface complications including dry eye, delayed corneal epithelial healing, and decreased corneal sensitivity. Most basic science and clinical studies focus on male sex in animal models in order to avoid confounders related to hormonal cycling. However, with approximately 10.2% of all women in the US aged 18-44 being diagnosed with diabetes and nearly 4% additional women having undiagnosed disease, it is prudent to examine the onset of these dysregulations also in females and to note any sex-related differences in the timing of onset or severity of ocular surface complications.Summary:Data from several well-controlled investigations have documented that female rats with type 1 diabetes develop ocular surface complications before male rats. In part, this finding may be due to the increase in the inhibitory peptide Opioid Growth Factor (OGF) that occurs within 2 weeks of the induction of hyperglycemia in female animals in comparison to the changes in OGF levels in male rats which occur at 4 weeks. It was noted that estrogen levels drop within weeks of induction of hyperglycemia and could serve as another marker for the onset of disease activity and/or its complications. Finally, insulin does not appear to protect against early changes in OGF levels or estrogen secretion in diabetic female rats, setting the stage for a distinction in the disease profile of diabetes between males and females. These data encourage further studies on both sexes in order to establish a complete understanding of the underlying pathologies associated with complications associated with diabetes.