Melatonin controls cell proliferation and modulates mitochondrial physiology in pancreatic stellate cells

Melatonin enhances everolimus efficacy in breast cancer by suppressing mTOR pathway activation and promoting apoptosis and mitochondrial function

BACKGROUND

Everolimus is used in the treatment of breast cancer by targeting the PI3K/AKT/mTOR pathway, particularly during anti-hormonal therapy. The efficacy of everolimus is limited due to a feedback loop that supresses mTOR while simultaneously enhancing Akt activation in endocrine-resistant breast cancer. Melatonin (N-acetyl-5-methoxytryptamine) regulates mitochondrial activity, cell death, and autophagy due to its strong free radical scavenging, antioxidant, and anti-inflammatory characteristics. Melatonin, a naturally occurring oncostatic agent, slows tumor growth in a range of malignancies, including breast cancer. Due to its ability to protect healthy cells from oxidative stress and inflammation, along with its anti-cancer properties, melatonin has the potential to serve asan effective adjuvant in breast cancer therapy. It also inhibits the phosphorylation of mTOR and Akt, two essential pathways implicated in breast cancer growth, which may aid in overcoming resistance to targeted treatments like everolimus. The combination effects of melatonin and everolimus on hormone receptor-positive breast cancer remains unexplored. This study examined the effectiveness of melatonin when combined with everolimus for the treatment of hormone receptor-positive breast cancer.

METHODS

To investigate the effects of melatonin and everolimus combination, we divided MCF-7 cells into four experimental groups: the control, Melatonin (3 mM), Everolimus (30 nM), and a combination of Melatonin and Everolimus (3 mM + 30 nM). Cell viability, apoptosis, autophagy activation, and mitochondrial function were evaluated using established techniques.

RESULTS

Based on the cell viability test, the combination of 30 nM everolimus and 3 mM melatonin inhibited phosphorylation of 4E-BP1 and p70S6K, which are downstream effectors of the mTOR pathway, and reduced cell growth. In addition, co-administration of melatonin and everolimus increased apoptosis and led to Sub-G1 phase accumulation. LC3 protein expression and LC3 puncta analysis demonstrated autophagic activity. In terms of mitochondrial function, co-administration of melatonin with everolimus did not cause proton leakage or mitochondrial uncoupling, but did restore everolimus-induced respiratory inhibition.

CONCLUSIONS

In conclusion, melatonin is thought to improve the effectiveness of everolimus by inhibiting mTOR downstream effectors, enhancing apoptosis, activating autophagy, improving mitochondrial respiration, and reducing MCF-7 growth.

The effects of melatonin on differentiated C2C12 myotubes in the absence of pathology: An oxygen-sparing action and enhancement of pro-survival signalling pathways

Previous research has demonstrated that melatonin protects against muscle damage while also improving the performance of injured muscle. However, its impact on healthy skeletal muscle remains largely unexplored. We exposed differentiated C2C12 myotubes to two melatonin concentrations (10 nM or 50 nM). The 10 nM concentration did not affect any of the mitochondrial respiration parameters. Whereas 50 nM concentration reduced mitochondrial complex II-linked oxidative phosphorylation (OXPHOS), electron transfer system (ETS) capacity, the contribution of complex II to ETS, and residual oxygen consumption (ROX). Neither concentration influenced the mitochondrial coupling control ratios, nor the coupling control efficiency ratios. Furthermore, neither concentration affected ATP production but reduced superoxide dismutase activity. The 50 nM increased catalase activity without affecting autophagy or citrate synthase activity. Moreover, 50 nM reduced activated JAK2 and STAT3 protein expression, while 10 nM reduced JAK2 without affecting STAT3. Th 50 nM increased activated AKT and ERK1/2 expression with no effect on p38 or PGC1-α expression. Our data suggests that melatonin (50 nM) triggers an oxygen-sparing effect on mitochondrial respiration, which is mediated via its antioxidant actions and its ability to enhance pro-survival pathways. Therefore, melatonin intake may have ergogenic effects on healthy muscles, in the absence of pathology, e.g., consumption before sporting events or physical exercise may aid in the reduction of oxidative stress often associated with such activities. However, this is an in vitro study, and therefore, the clinical relevance of the data should be considered with caution.

Melatonin protect against pregabalin-induced gonadotoxicity via anti-oxidative, anti-inflammatory, anti-apoptotic, enzymatic and hormonal regulatory mechanisms in rats

BACKGROUND

The therapeutic value of pregabalin in managing various pathological states, such as sleep, anxiety, and bipolar disorders, fibromyalgia, epilepsy, and others, cannot be overstated. Nevertheless, the gonadotoxicity of this drug remains a concern. In contrast, melatonin, an endogenous hormone, is known for its beneficial effects on reproductive tissues following various insults. Thus, this study aimed to examine the impact of melatonin on male Wistar rats exposed to pregabalin.

METHODS

A total of sixty male Wistar rats, weighing between 120 and 140 g, were randomly assigned to six groups, with each group consisting of ten rats. The control group was given 0.5 ml of normal saline orally, whereas melatonin was administered alone at 10 mg/kg/BW, and pregabalin was delivered at low and high doses of 150 and 300 mg/kg/BW orally, respectively. At the specified dosages, rats were also treated simultaneously with low and high doses of pregabalin in combination with melatonin. All treatments lasted for 56 days. Biomarkers were assayed in the testicular and epididymal tissues, while hormones were assayed in the serum.

RESULTS

Pregabalin treatment resulted in notable decreases in the percentage body weight change, testicular weight, relative testicular weight, FSH, LH, testosterone, 3β-HSD, 17β-HSD, SOD, catalase, and GSH, as compared to the control group. However, these effects were mitigated in the groups administered melatonin in conjunction with pregabalin. Pregabalin treatment also caused significant elevations in lactate, pyruvate, LDH, GGT, MDA, caspase, IL-1β, NF-κB, and TNF-α, and distorted testicular histoarchitecture, but these effects were blunted in the group co-administered with pregabalin and melatonin. The histological findings paralleled the biochemical assays.

CONCLUSION

Conclusively, melatonin has a protective effect against pregabalin-induced gonadotoxicity through anti-oxidative, anti-inflammatory, anti-apoptotic, enzymatic, and hormonal regulatory mechanisms.

CLINICAL TRIAL NUMBER

Not applicable.

Metabolism and bioenergetics in the pathophysiology of organ fibrosis

Fibrosis is the tissue scarring characterized by excess deposition of extracellular matrix (ECM) proteins, mainly collagens. A fibrotic response can take place in any tissue of the body and is the result of an imbalanced reaction to inflammation and wound healing. Metabolism has emerged as a major driver of fibrotic diseases. While glycolytic shifts appear to be a key metabolic switch in activated stromal ECM-producing cells, several other cell types such as immune cells, whose functions are intricately connected to their metabolic characteristics, form a complex network of pro-fibrotic cellular crosstalk. This review purports to clarify shared and particular cellular responses and mechanisms across organs and etiologies. We discuss the impact of the cell-type specific metabolic reprogramming in fibrotic diseases in both experimental and human pathology settings, providing a rationale for new therapeutic interventions based on metabolism-targeted antifibrotic agents.

Melatonin improves cognitive dysfunction and decreases gliosis in the streptozotocin-induced rat model of sporadic Alzheimer's disease

Introduction

Alzheimer's disease (AD) and other forms of dementia have a devastating effect on the community and healthcare system, as neurodegenerative diseases are causing disability and dependency in older population. Pharmacological treatment options are limited to symptomatic alleviation of cholinergic deficit and accelerated clearance of β-amyloid aggregates, but accessible disease-modifying interventions are needed especially in the early phase of AD. Melatonin was previously demonstrated to improve cognitive function in clinical setting and experimental studies also.

Methods

In this study, the influence of melatonin supplementation was studied on behavioral parameters and morphological aspects of the hippocampus and amygdala of rats. Streptozotocin (STZ) was injected intracerebroventricularly to induce AD-like symptoms in male adult Wistar rats (n = 18) which were compared to age-matched, sham-operated animals (n = 16). Melatonin was administered once daily in a dose of 20 mg/kg body weight by oral route. Behavioral analysis included open-field, novel object recognition, and radial-arm maze tests. TNF-α and MMP-9 levels were determined from blood samples to assess the anti-inflammatory and neuroprotective effects of melatonin. Immunohistological staining of brain sections was performed using anti-NeuN, anti-IBA-1, and anti-GFAP primary antibodies to evaluate the cellular reorganization of hippocampus.

Results and Discussion

The results show that after 40 days of treatment, melatonin improved the cognitive performance of STZ-induced rats and reduced the activation of microglia in both CA1 and CA3 regions of the hippocampus. STZ-injected animals had higher levels of GFAP-labeled astrocytes in the CA1 region, but melatonin treatment reduced this to that of the control group. In conclusion, melatonin may be a potential therapeutic option for treating AD-like cognitive decline and neuroinflammation.

Pancreatic stellate cells: Key players in pancreatic health and diseases (Review)

As a pluripotent cell, activated pancreatic stellate cells (PSCs) can differentiate into various pancreatic parenchymal cells and participate in the secretion of extracellular matrix and the repair of pancreatic damage. Additionally, PSCs characteristics allow them to contribute to pancreatic inflammation and carcinogenesis. Moreover, a detailed study of the pathogenesis of activated PSCs in pancreatic disease can offer promise for the development of innovative therapeutic strategies and improved patient prognoses. Therefore, the present study review aimed to examine the involvement of activated PSCs in pancreatic diseases and elucidate the underlying mechanisms to provide a viable therapeutic strategy for the management of pancreas‑related diseases.

COMP promotes pancreatic fibrosis by activating pancreatic stellate cells through CD36-ERK/AKT signaling pathways

BACKGROUND

Pancreatic fibrosis is one of the most important pathological features of chronic pancreatitis (CP) and pancreatic stellate cells (PSCs) are the key cells of fibrosis. As an extracellular matrix (ECM) glycoprotein, cartilage oligomeric matrix protein (COMP) is critical for collagen assembly and ECM stability and recent studies showed that COMP exert promoting fibrosis effect in the skin, lungs and liver. However, the role of COMP in activation of PSCs and pancreatic fibrosis remain unclear. We aimed to investigate the role and specific mechanisms of COMP in regulating the profibrotic phenotype of PSCs and pancreatic fibrosis.

METHODS

ELISA method was used to determine serum COMP in patients with CP. Mice model of CP was established by repeated intraperitoneal injection of cerulein and pancreatic fibrosis was evaluated by Hematoxylin-Eosin staining (H&E) and Sirius red staining. Immunohistochemical staining was used to detect the expression changes of COMP and fibrosis marker such as α-SMA and Fibronectin in pancreatic tissue of mice. Cell Counting Kit-8, Wound Healing and Transwell assessed the proliferation and migration of human pancreatic stellate cells (HPSCs). Western blotting, qRT-PCR and immunofluorescence staining were performed to detect the expression of fibrosis marker, AKT and MAPK family proteins in HPSCs. RNA-seq omics analysis as well as small interfering RNA of COMP, recombinant human COMP (rCOMP), MEK inhibitors and PI3K inhibitors were used to study the effect and mechanism of COMP on activation of HPSCs.

RESULTS

ELISA showed that the expression of COMP significantly increased in the serum of CP patients. H&E and Sirius red staining analysis showed that there was a large amount of collagen deposition in the mice in the CP model group and high expression of COMP, α-SMA, Fibronectin and Vimentin were observed in fibrotic tissues. TGF-β1 stimulates the activation of HPSCs and increases the expression of COMP. Knockdown of COMP inhibited proliferation and migration of HPSCs. Further, RNA-seq omics analysis and validation experiments in vitro showed that rCOMP could significantly promote the proliferation and activation of HPSCs, which may be due to promoting the phosphorylation of ERK and AKT through membrane protein receptor CD36. rCOMP simultaneously increased the expression of α-SMA, Fibronectin and Collagen I in HPSCs.

CONCLUSION

In conclusion, this study showed that COMP was up-regulated in CP fibrotic tissues and COMP induced the activation, proliferation and migration of PSCs through the CD36-ERK/AKT signaling pathway. COMP may be a potential therapeutic candidate for the treatment of CP. Interfering with the expression of COMP or the communication between COMP and CD36 on PSCs may be the next direction for therapeutic research.

Membrane Lipid Derivatives: Roles of Arachidonic Acid and Its Metabolites in Pancreatic Physiology and Pathophysiology

One of the most important constituents of the cell membrane is arachidonic acid. Lipids forming part of the cellular membrane can be metabolized in a variety of cellular types of the body by a family of enzymes termed phospholipases: phospholipase A2, phospholipase C and phospholipase D. Phospholipase A2 is considered the most important enzyme type for the release of arachidonic acid. The latter is subsequently subjected to metabolization via different enzymes. Three enzymatic pathways, involving the enzymes cyclooxygenase, lipoxygenase and cytochrome P450, transform the lipid derivative into several bioactive compounds. Arachidonic acid itself plays a role as an intracellular signaling molecule. Additionally, its derivatives play critical roles in cell physiology and, moreover, are involved in the development of disease. Its metabolites comprise, predominantly, prostaglandins, thromboxanes, leukotrienes and hydroxyeicosatetraenoic acids. Their involvement in cellular responses leading to inflammation and/or cancer development is subject to intense study. This manuscript reviews the findings on the involvement of the membrane lipid derivative arachidonic acid and its metabolites in the development of pancreatitis, diabetes and/or pancreatic cancer.