Recent Updates on the Involvement of PI3K/AKT/mTOR Molecular Cascade in the Pathogenesis of Hyperproliferative Skin Disorders

Multiplicative Effects of Essential Oils and Other Active Components on Skin Tissue and Skin Cancers

Naturally derived essential oils and their active components are known to possess various properties, ranging from anti-oxidant, anti-inflammatory, anti-bacterial, anti-fungal, and anti-cancer activities. Numerous types of essential oils and active components have been discovered, and their permissive roles have been addressed in various fields. In this comprehensive review, we focused on the roles of essential oils and active components in skin diseases and cancers as discovered over the past three decades. In particular, we opted to highlight the effectiveness of essential oils and their active components in developing strategies against various skin diseases and skin cancers and to describe the effects of the identified essential-oil-derived major components from physiological and pathological perspectives. Overall, this review provides a basis for the development of novel therapies for skin diseases and cancers, especially melanoma.

Imidazole propionate ameliorates atopic dermatitis-like skin lesions by inhibiting mitochondrial ROS and mTORC2

Background

Imidazole propionate (IMP) is a histidine metabolite produced by some gut microorganisms in the human colon. Increased levels of IMP are associated with intestinal inflammation and the development and progression of cardiovascular disease and diabetes. However, the anti-inflammatory activity of IMP has not been investigated. This study aimed to elucidate the role of IMP in treating atopic dermatitis (AD).

Methods

To understand how IMP mediates immunosuppression in AD, IMP was intraperitoneally injected into a Dermatophagoides farinae extract (DFE)/1-chloro-2,4 dinitrochlorobenzene (DNCB)-induced AD-like skin lesions mouse model. We also characterized the anti-inflammatory mechanism of IMP by inducing an AD response in keratinocytes through TNF-α/IFN-γ or IL-4 stimulation.

Results

Contrary to the prevailing view that IMP is an unhealthy microbial metabolite, we found that IMP-treated AD-like skin lesions mice showed significant improvement in their clinical symptoms, including ear thickness, epidermal and dermal thickness, and IgE levels. Furthermore, IMP antagonized the expansion of myeloid (neutrophils, macrophages, eosinophils, and mast cells) and Th cells (Th1, Th2, and Th17) in mouse skin and prevented mitochondrial reactive oxygen species production by inhibiting mitochondrial energy production. Interestingly, we found that IMP inhibited AD by reducing glucose uptake in cells to suppress proinflammatory cytokines and chemokines in an AD-like in vitro model, sequentially downregulating the PI3K and mTORC2 signaling pathways centered on Akt, and upregulating DDIT4 and AMPK.

Discussion

Our results suggest that IMP exerts anti-inflammatory effects through the metabolic reprogramming of skin inflammation, making it a promising therapeutic candidate for AD and related skin diseases.

Dihydromyrcenol Modulates Involucrin Expression through the Akt Signaling Pathway

The epidermis serves as a protective barrier against external threats and is primarily composed of keratinocytes, which ultimately form corneocytes. Involucrin, a protein integral to the cornified envelope, plays a pivotal role in preserving the functional integrity of the skin barrier. Previous studies have shown that Akt plays an important role in keratinocyte differentiation and skin barrier development. This study investigated whether dihydromyrcenol (DHM), a plant-derived terpene, could increase involucrin production in keratinocytes and sought to elucidate the possible underlying mechanisms. To accomplish this objective, we assessed the alterations in involucrin by DHM through quantitative PCR and Western blot on the HaCaT cell line. The changes in the promoter levels were investigated using luciferase assays. Furthermore, upstream mechanisms were explored through the use of siRNA and inhibitors. To strengthen our findings, the results were subsequently validated in primary cells and 3D skin equivalents. DHM significantly increased involucrin mRNA and protein levels in a concentration-dependent manner. In addition, the Fyn-Akt signaling pathway was found to be required for DHM-induced involucrin expression, as inhibition of Fyn or Akt blocked the increase in involucrin mRNA induced by DHM. The transcription factor Sp1, which is recognized as one of the transcription factors for involucrin, was observed to be activated in response to DHM treatment. Moreover, DHM increased epidermal thickness in a 3D human skin model. These findings suggest that the modulation of involucrin expression with DHM could improve skin barrier function and highlight the importance of manipulating the Akt pathway to achieve this improvement.

A Narrative Review of Current Knowledge on Cutaneous Melanoma

Cutaneous melanoma is a public health problem. Efforts to reduce its incidence have failed, as it continues to increase. In recent years, many risk factors have been identified. Numerous diagnostic systems exist that greatly assist in early clinical diagnosis. The histopathological aspect illustrates the grim nature of these cancers. Currently, pathogenic pathways and the tumor microclimate are key to the development of therapeutic methods. Revolutionary therapies like targeted therapy and immune checkpoint inhibitors are starting to replace traditional therapeutic methods. Targeted therapy aims at a specific molecule in the pathogenic chain to block it, stopping cell growth and dissemination. The main function of immune checkpoint inhibitors is to boost cellular immunity in order to combat cancer cells. Unfortunately, these therapies have different rates of effectiveness and side effects, and cannot be applied to all patients. These shortcomings are the basis of increased incidence and mortality rates. This study covers all stages of the evolutionary sequence of melanoma. With all these data in front of us, we see the need for new research efforts directed at therapies that will bring greater benefits in terms of patient survival and prognosis, with fewer adverse effects.

CD133-Dependent Activation of Phosphoinositide 3-Kinase /AKT/Mammalian Target of Rapamycin Signaling in Melanoma Progression and Drug Resistance

Melanoma frequently harbors genetic alterations in key molecules leading to the aberrant activation of PI3K and its downstream pathways. Although the role of PI3K/AKT/mTOR in melanoma progression and drug resistance is well documented, targeting the PI3K/AKT/mTOR pathway showed less efficiency in clinical trials than might have been expected, since the suppression of the PI3K/mTOR signaling pathway-induced feedback loops is mostly associated with the activation of compensatory pathways such as MAPK/MEK/ERK. Consequently, the development of intrinsic and acquired resistance can occur. As a solid tumor, melanoma is notorious for its heterogeneity. This can be expressed in the form of genetically divergent subpopulations including a small fraction of cancer stem-like cells (CSCs) and non-cancer stem cells (non-CSCs) that make the most of the tumor mass. Like other CSCs, melanoma stem-like cells (MSCs) are characterized by their unique cell surface proteins/stemness markers and aberrant signaling pathways. In addition to its function as a robust marker for stemness properties, CD133 is crucial for the maintenance of stemness properties and drug resistance. Herein, the role of CD133-dependent activation of PI3K/mTOR in the regulation of melanoma progression, drug resistance, and recurrence is reviewed.

Insights into Autophagic Machinery and Lysosomal Function in Cells Involved in the Psoriatic Immune-Mediated Inflammatory Cascade

Impaired autophagy, due to the dysfunction of lysosomal organelles, contributes to maladaptive responses by pathways central to the immune system. Deciphering the immune-inflammatory ecosystem is essential, but remains a major challenge in terms of understanding the mechanisms responsible for autoimmune diseases. Accumulating evidence implicates a role that is played by a dysfunctional autophagy-lysosomal pathway (ALP) and an immune niche in psoriasis (Ps), one of the most common chronic skin diseases, characterized by the co-existence of autoimmune and autoinflammatory responses. The dysregulated autophagy associated with the defective lysosomal system is only one aspect of Ps pathogenesis. It probably cannot fully explain the pathomechanism involved in Ps, but it is likely important and should be seriously considered in Ps research. This review provides a recent update on discoveries in the field. Also, it sheds light on how the dysregulation of intracellular pathways, coming from modulated autophagy and endolysosomal trafficking, characteristic of key players of the disease, i.e., skin-resident cells, as well as circulating immune cells, may be responsible for immune impairment and the development of Ps.

Signaling pathways and targeted therapies for psoriasis

Psoriasis is a common, chronic, and inflammatory skin disease with a high burden on individuals, health systems, and society worldwide. With the immunological pathologies and pathogenesis of psoriasis becoming gradually revealed, the therapeutic approaches for this disease have gained revolutionary progress. Nevertheless, the mechanisms of less common forms of psoriasis remain elusive. Furthermore, severe adverse effects and the recurrence of disease upon treatment cessation should be noted and addressed during the treatment, which, however, has been rarely explored with the integration of preliminary findings. Therefore, it is crucial to have a comprehensive understanding of the mechanisms behind psoriasis pathogenesis, which might offer new insights for research and lead to more substantive progress in therapeutic approaches and expand clinical options for psoriasis treatment. In this review, we looked to briefly introduce the epidemiology, clinical subtypes, pathophysiology, and comorbidities of psoriasis and systematically discuss the signaling pathways involving extracellular cytokines and intracellular transmission, as well as the cross-talk between them. In the discussion, we also paid more attention to the potential metabolic and epigenetic mechanisms of psoriasis and the molecular mechanistic cascades related to its comorbidities. This review also outlined current treatment for psoriasis, especially targeted therapies and novel therapeutic strategies, as well as the potential mechanism of disease recurrence.

Skin cancer: understanding the journey of transformation from conventional to advanced treatment approaches

Skin cancer is a global threat to the healthcare system and is estimated to incline tremendously in the next 20 years, if not diagnosed at an early stage. Even though it is curable at an early stage, novel drug identification, clinical success, and drug resistance is another major challenge. To bridge the gap and bring effective treatment, it is important to understand the etiology of skin carcinoma, the mechanism of cell proliferation, factors affecting cell growth, and the mechanism of drug resistance. The current article focusses on understanding the structural diversity of skin cancers, treatments available till date including phytocompounds, chemotherapy, radiotherapy, photothermal therapy, surgery, combination therapy, molecular targets associated with cancer growth and metastasis, and special emphasis on nanotechnology-based approaches for downregulating the deleterious disease. A detailed analysis with respect to types of nanoparticles and their scope in overcoming multidrug resistance as well as associated clinical trials has been discussed.

Case report: PIK3CA somatic mutation leading to Klippel Trenaunay Syndrome and multiple tumors

We report a case of Klippel Trenaunay Syndrome that was monitored both clinically and molecularly over a period of 9 years. A somatic mosaic mutation of PIK3CA (p(E545G)) was identified using both cfDNA NGS liquid biopsy and tissue biopsy. At the age of 56, due to intervening clonal mutations in PIK3CA background, she developed a squamous cell carcinoma in the right affected leg which was treated surgically. Nine years later, lung bilateral adenocarcinoma arose on PIK3CA mutated tissues supported by different clonal mutations. One year later, the patient died from metastases led by a new FGFR3 clone unresponsive to standard-of-care, immunotherapy-based. Our results highlight the presence of a molecular hallmark underlying neoplastic transformation that occurs upon an angiodysplastic process and support the view that PIK3CA mutated tissues must be treated as precancerous lesions. Importantly, they remark the effectiveness of combining cfDNA NGS liquid and tissue biopsies to monitor disease evolution as well as to identify aggressive clones targetable by tailored therapy, which is more efficient than conventional protocols.

LY294002 ameliorates psoriatic skin inflammation in mice via blocking the Notch1/Hes1-PTEN/AKT/IL-17A feedback loop

(IL)-17A, the effective factor of Th17 cells, acts an important pathological role in the pathogenesis of psoriasis. Notch1/hairy and split 1 (Hes1) and PI3K/AKT signaling pathways are interpenetrated and involved in Th17 cell differentiation and IL-17A production. In this present study, we used imiquimod (IMQ)-induced mouse psoriatic skin inflammation to explore the possible mechanism of Notch1/Hes1-PTEN/AKT/IL-17A feedback loop in psoriasis by employing AKT inhibitor LY294002 as an intervention with the methods of flow cytometry analysis, reverse transcription-quantitative polymerase chain reaction, western blot, co-immunoprecipitation, and immunofluorescence. First, LY294002 inhibition can obviously alleviate the mouse psoriatic skin inflammation both in skin structural and histopathological characteristics, which is similar to the changes found in IL-17A antibody-treated mice. Additionally, the interaction between Notch1 intracellular domain (NICD1) and nuclear factor kappa B (NF-κB) activator 1 (Act1) was demonstrated. LY294002 interruption resulted in consistent changes in expression levels of key signaling molecules both in Notch1/Hes1 and PI3K/AKT signaling pathways in a time-dependent manner. Moreover, chloroquine (CQ) can partly reverse the inhibitory effects of LY294002 on the Notch1/Hes1-PTEN/AKT/IL-17A feedback loop by affecting Notch1 ubiquitination and lysosomal degradation. The present study showed that LY294002 can exert the inhibitory effect on Notch1/Hes1-PTEN/AKT/IL-17A feedback loop to regulate Th17 cell differentiation and IL-17A function in the process of psoriasis, which provides a new possible therapeutic strategy for psoriasis.

Prdx5 in the Regulation of Tuberous Sclerosis Complex Mutation-Induced Signaling Mechanisms

(1) Background: Tuberous sclerosis complex (TSC) mutations directly affect mTORC activity and, as a result, protein synthesis. In several cancer types, TSC mutation is part of the driver mutation panel. TSC mutations have been associated with mitochondrial dysfunction, tolerance to reactive oxygen species due to increased thioredoxin reductase (TrxR) enzyme activity, tolerance to endoplasmic reticulum (ER) stress, and apoptosis. The FDA-approved drug rapamycin is frequently used in clinical applications to inhibit protein synthesis in cancers. Recently, TrxR inhibitor auranofin has also been involved in clinical trials to investigate the anticancer efficacy of the combination treatment with rapamycin. We aimed to investigate the molecular background of the efficacy of such drug combinations in treating neoplasia modulated by TSC mutations. (2) Methods: TSC2 mutant and TSC2 wild-type (WT) cell lines were exposed to rapamycin and auranofin in either mono- or combination treatment. Mitochondrial membrane potential, TrxR enzyme activity, stress protein array, mRNA and protein levels were investigated via cell proliferation assay, electron microscopy, etc. (3) Results: Auranofin and rapamycin normalized mitochondrial membrane potential and reduced proliferation capacity of TSC2 mutant cells. Database analysis identified peroxiredoxin 5 (Prdx5) as the joint target of auranofin and rapamycin. The auranofin and the combination of the two drugs reduced Prdx5 levels. The combination treatment increased the expression of heat shock protein 70, a cellular ER stress marker. (4) Conclusions: After extensive analyses, Prdx5 was identified as a shared target of the two drugs. The decreased Prdx5 protein level and the inhibition of both TrxR and mTOR by rapamycin and auranofin in the combination treatment made ER stress-induced cell death possible in TSC2 mutant cells.

The PI3K-Akt-mTOR and Associated Signaling Pathways as Molecular Drivers of Immune-Mediated Inflammatory Skin Diseases: Update on Therapeutic Strategy Using Natural and Synthetic Compounds

The dysregulated phosphatidylinositol-3-kinase (PI3K)-Akt-mammalian target of rapamycin (mTOR) signaling pathway has been implicated in various immune-mediated inflammatory and hyperproliferative dermatoses such as acne, atopic dermatitis, alopecia, psoriasis, wounds, and vitiligo, and is associated with poor treatment outcomes. Improved comprehension of the consequences of the dysregulated PI3K/Akt/mTOR pathway in patients with inflammatory dermatoses has resulted in the development of novel therapeutic approaches. Nonetheless, more studies are necessary to validate the regulatory role of this pathway and to create more effective preventive and treatment methods for a wide range of inflammatory skin diseases. Several studies have revealed that certain natural products and synthetic compounds can obstruct the expression/activity of PI3K/Akt/mTOR, underscoring their potential in managing common and persistent skin inflammatory disorders. This review summarizes recent advances in understanding the role of the activated PI3K/Akt/mTOR pathway and associated components in immune-mediated inflammatory dermatoses and discusses the potential of bioactive natural products, synthetic scaffolds, and biologic agents in their prevention and treatment. However, further research is necessary to validate the regulatory role of this pathway and develop more effective therapies for inflammatory skin disorders.

Activation of Sestrin2 accelerates deep second-degree burn wound healing through PI3K/AKT pathway

Deep second-degree burns heal slowly, and promoting the healing process is a focus of clinical research. Sestrin2 is a stress-inducible protein with antioxidant and metabolic regulatory effects. However, its role during acute dermal and epidermal re-epithelialization in deep second-degree burns is unknown. In this study, we aimed to explore the role and molecular mechanism of sestrin2 in deep second-degree burns as a potential treatment target for burn wounds. To explore the effects of sestrin2 on burn wound healing, we established a deep second-degree burn mouse model. Then we detected the expression of sestrin2 by western blot and immunohistochemistry after obtaining the wound margin of full-thickness burned skin. The effects of sestrin2 on burn wound healing were explored in vivo and in vitro through interfering sestrin2 expression using siRNAs or the small molecule agonist of sestrin2, eupatilin. We also investigated the molecular mechanism of sestrin2 in promoting burn wound healing by western blot and CCK-8 assay. Our in vivo and in vitro deep second-degree burn wound healing model demonstrated that sestrin2 was promptly induced at murine skin wound edges. The small molecule agonist of sestrin2 accelerated the proliferation and migration of keratinocytes, as well as burn wound healing. Conversely, the healing of burn wounds was delayed in sestrin2-deficient mice and was accompanied by the secretion of inflammatory cytokines as well as the suppression of keratinocyte proliferation and migration. Mechanistically, sestrin2 promoted the phosphorylation of the PI3K/AKT pathway, and inhibition of PI3K/AKT pathway abrogated the promoting role of sestrin2 in keratinocyte proliferation and migration. Therefore, sestrin2 plays a critical role in activation of the PI3K/AKT pathway to promote keratinocyte proliferation and migration, as well as re-epithelialization in the process of deep second-degree burn wound repair.

Diosmin nanocrystal gel alleviates imiquimod-induced psoriasis in rats via modulating TLR7,8/NF-κB/micro RNA-31, AKT/mTOR/P70S6K milieu, and Tregs/Th17 balance

Diosmin is a flavonoid with promising anti-inflammatory and antioxidant properties. However, it has difficult physicochemical characteristics since its solubility demands a pH level of 12, which has an impact on the drug's bioavailability. The aim of this work is the development and characterization of diosmin nanocrystals using anti-solvent precipitation technique to be used for topical treatment of psoriasis. Results revealed that diosmin nanocrystals stabilized with hydroxypropyl methylcellulose (HPMC E15) in ratio (diosmin:polymer; 1:1) reached the desired particle size (276.9 ± 16.49 nm); provided promising colloidal properties and possessed high drug release profile. Additionally, in-vivo assessment was carried out to evaluate and compare the activities of diosmin nanocrystal gel using three different doses and diosmin powder gel in alleviating imiquimod-induced psoriasis in rats and investigating their possible anti-inflammatory mechanisms. Herein, 125 mg of 5% imiquimod cream (IMQ) was applied topically for 5 consecutive days on the shaved backs of rats to induce psoriasis. Diosmin nanocrystal gel especially in the highest dose used offered the best anti-inflammatory effect. This was confirmed by causing the most statistically significant reduction in the psoriasis area severity index (PASI) score and the serum inflammatory cytokines levels. Furthermore, it was capable of maintaining the balance between T helper (Th17) and T regulatory (Treg) cells. Moreover, it tackled TLR7/8/NF-κB, miRNA-31, AKT/mTOR/P70S6K and elevated the TNFAIP3/A20 (a negative regulator of NF-κB) expression in psoriatic skin tissues. This highlights the role of diosmin nanocrystal gel in tackling imiquimod-induced psoriasis in rats, and thus it could be a novel promising therapy for psoriasis.

Black Tea Extract, via Modulation of TGF-β Pathway, Prevents Inorganic Arsenic-induced Development of Squamous Cell Carcinoma of the Skin in Swiss Albino Mice

Chronic exposure to inorganic arsenic (iAs) elevates reactive oxygen species (ROS) generation and up-regulates TGF-β signalling. This promotes induction of epithelial to mesenchymal transition (EMT) and causes the development of squamous cell carcinoma (SCC) of skin. Black tea is a popular beverage worldwide and an effective antioxidant. Chemopreventive potential of black tea extract (BTE) against iAs induced carcinogenicity has been explored here. The study aims to investigate the role of BTE in prevention of iAs-induced SCC of skin in Swiss albino mice via the modulation of TGF-β signalling and EMT. Mice were divided into (1) control, (2) iAs, (3) iAs+BTE, and (4) BTE groups and were administered iAs and BTE alone, or in combination for 330 days. Histological studies were performed to assess development of SCC. ROS generation was estimated by flowcytometry. Expression of TGF-β and downstream proteins belonging to suppressor of mothers against decapentaplegic (Smad), phosphoinositide-3-kinase (PI3K)-protein kinase B (AKT) and mitogen-activated protein kinase (MAPK) pathways was assessed by immunoblotting. Expression of EMT markers was evaluated by immunoblotting, immunohistochemistry and semi-quantitative reverse transcriptase-PCR. After 330 days of iAs treatment, development of invasive SCC of skin probably due to excess ROS generation, elevation of TGF-β, downregulation of the Smad pathway, upregulation of PI3K-AKT and MAPK signalling molecules and induction of EMT was observed. All these modulations were found to be reversed by BTE, which inhibits iAs induced SCC of skin by quenching excess ROS, promoting Smad mediated TGF-β signalling, downregulating signalling intermediates of PI3K-AKT and MAPK pathways and inhibiting EMT.

Efficacy of topically applied rapamycin-loaded redox-sensitive nanocarriers in a human skin/T cell co-culture model

Rapamycin, also known as Sirolimus, is a promising anti-proliferative drug, but its therapeutic use for the topical treatment of inflammatory, hyperproliferative skin disorders is limited by insufficient penetration rates due to its high molecular weight (MW of 914.172 g/mol) and high lipophilicity. We have shown that core multi-shell (CMS) nanocarriers sensitive to oxidative environment can improve drug delivery to the skin. In this study, we investigated the mTOR inhibitory activity of these oxidation-sensitive CMS (osCMS) nanocarrier formulations in an inflammatory ex vivo human skin model. In this model, features of inflamed skin were introduced by treating the ex vivo tissue with low-dose serine protease (SP) and lipopolysaccharide (LPS), while phorbol 12-myristate 13-acetate and ionomycin were used to stimulate IL-17A production in the co-cultured SeAx cells. Furthermore, we tried to elucidate the effects of rapamycin on single cell populations isolated from skin (keratinocytes, fibroblast) as well as on SeAx cells. Further, we measured possible effects of the rapamycin formulations on dendritic cell (DC) migration and activation. The inflammatory skin model enabled the assessment of biological readouts at both the tissue and T cell level. All investigated formulations successfully delivered rapamycin across the skin as revealed by reduced IL-17A levels. Nevertheless, only the osCMS formulations reached higher anti-inflammatory effects in the skin compared to the control formulations with a significant downregulation of mTOR activity. These results indicate that osCMS formulations could help to establish rapamycin, or even other drugs with similar physico-chemical properties, in topical anti-inflammatory therapy.

Dual targeting of mTOR/IL-17A and autophagy by fisetin alleviates psoriasis-like skin inflammation

Psoriasis is a chronic autoimmune inflammatory skin disorder characterized by epidermal hyperplasia and aberrant immune response. In addition to aberrant cytokine production, psoriasis is associated with activation of the Akt/mTOR pathway. mTOR/S6K1 regulates T-lymphocyte activation and migration, keratinocytes proliferation and is upregulated in psoriatic lesions. Several drugs that target Th1/Th17 cytokines or their receptors have been approved for treating psoriasis in humans with variable results necessitating improved therapies. Fisetin, a natural dietary polyphenol with anti-oxidant and anti-proliferative properties, covalently binds mTOR/S6K1. The effects of fisetin on psoriasis and its underlying mechanisms have not been clearly defined. Here, we evaluated the immunomodulatory effects of fisetin on Th1/Th17-cytokine-activated adult human epidermal keratinocytes (HEKa) and anti-CD3/CD28-stimulated inflammatory CD4+ T cells and compared these activities with those of rapamycin (an mTOR inhibitor). Transcriptomic analysis of HEKa revealed 12,713 differentially expressed genes (DEGs) in the fisetin-treated group compared to 7,374 DEGs in the rapamycin-treated group, both individually compared to a cytokine treated group. Gene ontology analysis revealed enriched functional groups related to PI3K/Akt/mTOR signaling pathways, psoriasis, and epidermal development. Using in silico molecular modeling, we observed a high binding affinity of fisetin to IL-17A. In vitro, fisetin significantly inhibited mTOR activity, increased the expression of autophagy markers LC3A/B and Atg5 in HEKa cells and suppressed the secretion of IL-17A by activated CD4+ T lymphocytes or T lymphocytes co-cultured with HEKa. Topical administration of fisetin in an imiquimod (IMQ)-induced mouse psoriasis model exhibited a better effect than rapamycin in reducing psoriasis-like inflammation and Akt/mTOR phosphorylation and promoting keratinocyte differentiation and autophagy in mice skin lesions. Fisetin also significantly inhibited T-lymphocytes and F4/80+ macrophage infiltration into skin. We conclude that fisetin potently inhibits IL-17A and the Akt/mTOR pathway and promotes keratinocyte differentiation and autophagy to alleviate IMQ-induced psoriasis-like disease in mice. Altogether, our findings suggest fisetin as a potential treatment for psoriasis and possibly other inflammatory skin diseases.

miR-27a Targeting PIK3R3 Regulates the Proliferation and Apoptosis of Sheep Hair Follicle Stem Cells

Micro RNAs are regulatory factors in tissue development, organ formation, cell growth, apoptosis and other biological processes. In particular, several miRNAs are related to the development of hair follicles. Here, we investigated the effect of the targeting of PIK3R3 by miR-27a on the AKT/MTOR pathway and on the proliferation and apoptosis of hair follicle stem cells (HFSCs) in sheep. Knockdown of the expression of PIK3R3 was found to significantly inhibit the proliferation and promote the apoptosis of HFSCs. Similarly, a miR-27a mimic significantly inhibited the proliferation and promoted the apoptosis of HFSCs. The miR-27a mimic was also shown to significantly inhibit the expression of PIK3R3, AKT, and MTOR and the phosphorylation of AKT and MTOR, while a miR-27a inhibitor increased the expression of these genes. The presence of an miR-27a binding site in the 3' UTR of PIK3R3 was identified by a bioinformatics analysis, and the interaction was verified with a dual-luciferase reporter assay. The expression of PIK3R3 mRNA and protein was negatively correlated with the presence of miR-27a, which suggests that this interaction may be involved in the biological impacts on proliferation and apoptosis. Thus, this study demonstrates that miR-27a plays a potential role in the proliferation and apoptosis of sheep hair follicle stem cells by targeting PIK3R3, which can be used to design new methods to improve sheep wool.

Aruncus dioicus var. kamtschaticus Extract Ameliorates Psoriasis-like Skin Inflammation via Akt/mTOR and JAK2/STAT3 Signaling Pathways in a Murine Model

Goat's beard (Aruncus dioicus var. kamtschaticus) is a traditional medicinal plant, widely used in Chinese and Korean traditional medicine because of its anti-inflammatory, anti-oxidant, antimicrobial, and anti-cancer activity. However, its effect on skin inflammatory diseases like psoriasis is unknown. The aim of this study was to investigate the therapeutic potency of A. dioicus extract (ADE) in in vitro and in vivo psoriasis models. ADE treatment significantly attenuated skin inflammation and improved skin integrity in imiquimod-treated mice by suppressing keratinocyte hyperproliferation, inhibiting the infiltration of immune cells, and downregulating the expression of psoriatic markers. Further, ADE treatment suppressed protein kinase B/mammalian target of rapamycin (Akt/mTOR) and Janus kinase 2/signal transducers and activators of transcription 3 (JAK2/STAT3) signaling in HaCaT cells. Overall, the application of ADE relieves psoriasis-like skin inflammation possibly by regulating the Akt/mTOR and JAK2/STAT3 signaling pathways, making it an effective alternative for psoriasis therapy.

Effect of Azelaic Acid on Psoriasis Progression Investigated Based on Phosphatidylinositol 3-Kinase (PI3K)/Protein Kinase B (AKT) Signaling Pathway

OBJECTIVE

To probe into the effect of azelaic acid on psoriasis based on the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT) signaling pathway.

METHODS

Psoriasis gene expression data were downloaded from the GEO database for differential expression analysis to identify differentially expressed genes (DEGs). KEGG and GSEA analyses were performed to identify important signaling pathways that may be involved in psoriasis progression for subsequent validation. Thirty-six C57BL/6 mice aged 8 weeks old were randomly assigned into the blank control group (n = 9), negative control group (n = 9), psoriasis model group (n = 9), and azelaic acid treat group (n = 9). Mice models of psoriasis were prepared with imiquimod (IMQ) in the latter two groups, and azelaic acid ointment was applied in azelaic acid treat group. Then, hematoxylin-eosin (HE) staining was carried out to detect the effect of azelaic acid on the pathological damage of mice models of psoriasis in each group. HaCaT cells cultured in vitro were divided into blank control group, negative control group (addition of azelaic acid), IL-17 group (20 ng/mL) and IL-17+azelaic acid group, with 3 replicates for each group. Immunofluorescence assay and Western blotting were used to detect the protein expression of PI3K/AKT signaling pathway related molecules.

RESULTS

KEGG analysis showed that DEGs were significantly enriched in PI3K-AKT signaling pathway. GSEA analysis showed that PI3K and MTOR signaling pathways were up-regulated in psoriasis, while AUTOPHAGY signaling pathway was down-regulated. HE staining showed that azelaic acid could significantly inhibit the local skin injury in mice caused by IMQ-induced psoriasis. Moreover, azelaic acid can inhibit the expression of PI3K/AKT signaling pathway related proteins phosphorylated (p)-PI3K, p-AKT, p-mammalian target of rapamycin (mTOR), vascular endothelial growth factor (VEGF), cyclooxygenase-2 (COX-2), angiogenin-1 and hypoxia-inducible factor-1α (HIF-1α). These results imply that azelaic acid may inhibit the activation of PI3K/AKT signaling pathway and angiogenesis, thereby improving the symptoms of psoriasis.

CONCLUSION

Azelaic acid may inhibit the activation of PI3K/AKT signaling pathway and angiogenesis, thereby improving the symptoms of psoriasis.

Network pharmacology and molecular docking-based prediction of active compounds and mechanisms of action of Cnidii Fructus in treating atopic dermatitis

BACKGROUND

Atopic dermatitis (AD) is a common inflammatory skin disease that compromises the skin's barrier function and capacity to retain moisture. Cnidii Fructus (CF), the dried fruits of Cnidium monnieri, has long been used to treat atopic dermatitis (AD) in China. However, the anti-AD compounds and mechanisms of CF are not fully understood. In this study, we evaluated the active compounds and molecular targets of CF in treating AD.

METHODS

The Traditional Chinese Medicine Systems Pharmacology database was used to acquire information regarding the compounds that occur in the herb. Targets of these compounds were predicted using the SwissTargetPrediction website tool. AD-related genes were collected from the GeneCards database. Gene ontology (GO) enrichment analysis and KEGG pathway analysis of proteins that are targeted by active compounds of CF and encoded by AD-related genes were performed using Database for Annotation, Visualization, and Integrated Discovery Bioinformatics Resources. A "compound-target" network was constructed and analyzed using Cytoscape Software. Molecular docking was performed using BIOVIA Discovery Studio Visualizer and AutoDock Vina.

RESULTS

We identified 19 active compounds in CF, 532 potential targets for these compounds, and 1540 genes related to AD. Results of GO enrichment indicated that CF affects biological processes and molecular functions, such as inflammatory response and steroid hormone receptor activity, which may be associated with its anti-AD effects. KEGG pathway analyses showed that PI3K-Akt signaling, calcium signaling, Rap1 signaling, and cAMP signaling pathways are the main pathways involved in the anti-AD effects of CF. Molecular docking analyses revealed that the key active compounds in CF, such as (E)-2,3-bis(2-keto-7-methoxy-chromen-8-yl)acrolein, ar-curcumene, and diosmetin, can bind the main therapeutic targets AKT1, SRC, MAPK3, EGFR, CASP3, and PTGS2.

CONCLUSIONS

Results of the present study establish a foundation for further investigation of the anti-AD compounds and mechanisms of CF and provide a basis for developing modern anti-AD agents based on compounds that occur in CF.

Mechanotransduction in skin wound healing and scar formation: Potential therapeutic targets for controlling hypertrophic scarring

Hypertrophic scarring (HTS) is a major source of morbidity after cutaneous injury. Recent studies indicate that mechanical force significantly impacts wound healing and skin regeneration which opens up a new direction to combat scarring. Hence, a thorough understanding of the underlying mechanisms is essential in the development of efficacious scar therapeutics. This review provides an overview of the current understanding of the mechanotransduction signaling pathways in scar formation and some strategies that offload mechanical forces in the wounded region for scar prevention and treatment.

ITGA5 Promotes Tumor Progression through the Activation of the FAK/AKT Signaling Pathway in Human Gastric Cancer

Background

ITGA5 is an adhesion molecule that integrates the intracellular structures with the extracellular matrix to perform biological functions. However, ITGA5 is highly expressed in a variety of tumors and is involved in tumor progression by promoting cell proliferation and metastasis. Nevertheless, little research has been performed on its function in gastric cancer. Therefore, the aim of this study was to investigate the role of ITGA5 in gastric cancer, focusing on the mechanism regulating the proliferation, invasion and migration.

Methods

The expression of ITGA5 in gastric cancer tissues was assessed by the use of molecular bioinformatics databases and high-throughput sequencing of gastric cancer tissues from patients. Western blot, qPCR, and immunohistochemistry were performed to detect the expression of ITGA5 in samples from gastric cancer patients and gastric cancer cell lines. Furthermore, the ITGA5 gene was silenced and overexpressed in gastric cancer cells, and the effect on proliferation, invasion, migration, and tumorigenic ability was assessed.

Results

ITGA5 mRNA and protein expression were upregulated in gastric cancer cell lines and tissues from patients, and its expression was closely associated with tumor size, lymph node metastasis, and TNM stage. In vitro and in vivo experiments showed that ITGA5 silencing resulted in the inhibition of proliferation, invasion, migration, and graft growth of gastric cancer cells; conversely, the overexpression resulted in the promotion of these cell functions. Our results finally showed that the effect of ITGA5 on proliferation, invasion, and migration of gastric cancer cells was performed through the activation of the FAK/AKT pathway.

Conclusions

ITGA5 promotes proliferation, invasion, and migration of gastric cancer cells through the activation of FAK/AKT signaling pathway, suggesting that ITGA5 may be potentially considered as a new target in gastric cancer therapy.

Modulation of Hedgehog Signaling for the Treatment of Basal Cell Carcinoma and the Development of Preclinical Models

Basal Cell Carcinoma (BCC) is the most commonly diagnosed cancer worldwide. While the survivability of BCC is high, many patients are excluded from clinically available treatments due to health risks or personal choice. Further, patients with advanced or metastatic disease have severely limited treatment options. The dysregulation of the Hedgehog (Hh) signaling cascade drives onset and progression of BCC. As such, the modulation of this pathway has driven advancements in BCC research. In this review, we focus firstly on inhibitors that target the Hh pathway as chemotherapeutics against BCC. Two therapies targeting Hh signaling have been made clinically available for BCC patients, but these treatments suffer from limited initial efficacy and a high rate of chemoresistant tumor recurrence. Herein, we describe more recent developments of chemical scaffolds that have been designed to hopefully improve upon the available therapeutics. We secondly discuss the history and recent efforts involving modulation of the Hh genome as a method of producing in vivo models of BCC for preclinical research. While there are many advancements left to be made towards improving patient outcomes with BCC, it is clear that targeting the Hh pathway will remain at the forefront of research efforts in designing more effective chemotherapeutics as well as relevant preclinical models.

LncRNA NEAT1 Targets miR-342-3p/CUL4B to Inhibit the Proliferation of Cutaneous Squamous Cell Carcinoma Cells

Objective. This study investigated whether lncRNA NEAT1 could inhibit the proliferation of cutaneous squamous cell carcinoma (CSCC) cells by targeting miR-342-3p/CUL4B, thereby affecting the occurrence and development of CSCC. Methods. Fluorescence quantitative PCR was used to detect the expression of lncRNA NEAT1 and miR-42-3p in skin squamous cell carcinoma and adjacent tissues. Bioinformatics software and luciferase reporter gene assay were used to analyze the association of lncRNA NEAT1 and miR-342-3p. The effect of overexpression or knockdown of miR-342-3p on the proliferation of CSCC cells was examined by MTT and colony formation assays. Western blotting was used to detect the proteins of the miR-342-3p/CUL4B signaling axis. Results. The lncRNA NEAT1 is abnormally overexpressed in CSCC tissues and cell lines. The expression of lncRNA NEAT1 and miR-342-3p in CSCC was negatively correlated. Bioinformatics prediction analysis revealed that lncRNA NEAT1 regulates the expression of miR-342-3p. The results of MTT and plate colony formation experiments showed that the transfection of miR-342-3p mimics significantly inhibited the proliferation and plate colony formation of CSCC cells, while the transfection of miR-342-3p inhibitor significantly promoted the proliferation and plate colony-forming ability of CSCC cells. Western blot results showed that lncRNA NEAT1 affected CSCC cell proliferation through miR-342-3p/CUL4B/PI3K-Akt signaling pathway. Conclusion. The expression of lncRNA NEAT1 and miR-342-3p in CSCC tissues was negatively correlated. This study is the first to demonstrate that the lncRNA NEAT1, as a ceRNA, affects the proliferation of skin squamous cell carcinoma cells through the miR-342-3p/CUL4B/PI3K-Akt signaling pathway. Therefore, lncRNA NEAT1 could be a biological marker or target for CSCC diagnosis or treatment.

Post-Translational Modifications in Atopic Dermatitis: Current Research and Clinical Relevance

Atopic dermatitis (AD) is a chronic and relapsing cutaneous disorder characterized by compromised immune system, excessive inflammation, and skin barrier disruption. Post-translational modifications (PTMs) are covalent and enzymatic modifications of proteins after their translation, which have been reported to play roles in inflammatory and allergic diseases. However, less attention has been paid to the effect of PTMs on AD. This review summarized the knowledge of six major classes (including phosphorylation, acetylation, ubiquitination, SUMOylation, glycosylation, o-glycosylation, and glycation) of PTMs in AD pathogenesis and discussed the opportunities for disease management.

Role of mTOR Signaling Cascade in Epidermal Morphogenesis and Skin Barrier Formation

Simple Summary

The skin epidermis is a stratified multilayered epithelium that provides a life-sustaining protective and defensive barrier for our body. The barrier machinery is established and maintained through a tightly regulated keratinocyte differentiation program. Under normal conditions, the basal layer keratinocytes undergo active proliferation and migration upward, differentiating into the suprabasal layer cells. Perturbation of the epidermal differentiation program often results in skin barrier defects and inflammatory skin disorders. The protein kinase mechanistic target of rapamycin (mTOR) is the central hub of cell growth, metabolism and nutrient signaling. Over the past several years, we and others using transgenic mouse models have unraveled that mTOR signaling is critical for epidermal differentiation and barrier formation. On the other hand, there is increasing evidence that disturbed activation of mTOR signaling is significantly implicated in the development of various skin diseases. In this review, we focus on the formation of skin barrier and discuss the current understanding on how mTOR signaling networks, including upstream inputs, kinases and downstream effectors, regulate epidermal differentiation and skin barrier formation. We hope this review will help us better understand the metabolic signaling in the epidermis, which may open new vistas for epidermal barrier defect-associated disease therapy.

Abstract

The skin epidermis, with its capacity for lifelong self-renewal and rapid repairing response upon injury, must maintain an active status in metabolism. Mechanistic target of rapamycin (mTOR) signaling is a central controller of cellular growth and metabolism that coordinates diverse physiological and pathological processes in a variety of tissues and organs. Recent evidence with genetic mouse models highlights an essential role of the mTOR signaling network in epidermal morphogenesis and barrier formation. In this review, we focus on the recent advances in understanding how mTOR signaling networks, including upstream inputs, kinases and downstream effectors, regulate epidermal morphogenesis and skin barrier formation. Understanding the details of the metabolic signaling will be critical for the development of novel pharmacological approaches to promote skin barrier regeneration and to treat epidermal barrier defect-associated diseases.

Notch1/Hes1‑PTEN/AKT/IL‑17A feedback loop regulates Th17 cell differentiation in mouse psoriasis‑like skin inflammation

IL‑17A, the effector cytokine of T helper (Th) 17 cells, plays a crucial role in the pathogenesis of psoriasis. The Notch1 and PI3K/AKT signaling pathways are implicated in Th17 cell differentiation and IL‑17A production. The present study aimed to evaluate the regulatory effect of the Notch1/hairy and enhancer of split 1 (Hes1)‑PTEN/AKT/IL‑17A feedback loop on Th17 cell differentiation via the PI3K/AKT inhibitor LY294002 in a mouse model of psoriasis. Mice were randomly divided into 3 groups: a control group, a model group [5% imiquimod (IMQ)‑induced group] and an intervention group (5% IMQ‑induced plus LY294002‑treated group). Skin structural characteristics were recorded and evaluated by hematoxylin and eosin staining. The weights of the spleens and inguinal lymph nodes were measured. Th17 cell percentage, as well as the mRNA and protein expression levels of Notch1, Notch1 intracellular domain (NICD1), Hes1, PTEN, AKT, phosphorylated (p)‑AKT, mTOR complex 1 (mTORC1), p‑mTORC1, S6 kinase (S6K)1, S6K2 and IL‑17A were detected in skin samples of the three experimental groups. Additionally, splenic mononuclear cells from model mice were treated by 10 and 50 µM LY294002 to further evaluate its regulatory effect on Notch1/Hes1‑PTEN/AKT/IL‑17A feedback loop. Increased Th17 cell percentage, increased expression of Notch1, NICD1, Hes1, AKT, p‑AKT, mTORC1, p‑mTORC1, S6K1, S6K2 and IL‑17A, and decreased PTEN levels were observed in model mice alongside marked psoriasis‑like skin inflammation, splenomegaly and lymphadenopathy. LY294002 treatment significantly alleviated the severity of psoriasis‑like skin inflammation in the intervention mice, attenuated the degree of epidermal hyperplasia and dermal inflammatory cell infiltration, and mitigated splenomegaly and lymphadenopathy. In addition, LY294002 treatment reversed the increased Th17 cell percentage, as well as the increased expression of Notch1, NICD1, Hes1, AKT, p‑AKT, mTORC1, p‑mTORC1, S6K1, S6K2 and IL‑17A, and the decreased expression of PTEN. In vitro study from 5% IMQ‑induced mouse splenic mononuclear cells presented that high dose of LY294002 exerted more obviously regulatory effect on Notch1/Hes1‑PTEN/AKT/IL‑17A feedback loop. The current findings suggested that the Notch1/Hes1‑PTEN/AKT/IL‑17A feedback loop regulates Th17 cell differentiation within the disease environment of psoriasis. Blocking the Notch1/Hes1‑PTEN/AKT/IL‑17A feedback loop may thus be a potential therapeutic method for management of psoriatic inflammation.

Revisiting the Roles of Filaggrin in Atopic Dermatitis

The discovery in 2006 that loss-of-function mutations in the filaggrin gene (FLG) cause ichthyosis vulgaris and can predispose to atopic dermatitis (AD) galvanized the dermatology research community and shed new light on a skin protein that was first identified in 1981. However, although outstanding work has uncovered several key functions of filaggrin in epidermal homeostasis, a comprehensive understanding of how filaggrin deficiency contributes to AD is still incomplete, including details of the upstream factors that lead to the reduced amounts of filaggrin, regardless of genotype. In this review, we re-evaluate data focusing on the roles of filaggrin in the epidermis, as well as in AD. Filaggrin is important for alignment of keratin intermediate filaments, control of keratinocyte shape, and maintenance of epidermal texture via production of water-retaining molecules. Moreover, filaggrin deficiency leads to cellular abnormalities in keratinocytes and induces subtle epidermal barrier impairment that is sufficient enough to facilitate the ingress of certain exogenous molecules into the epidermis. However, although FLG null mutations regulate skin moisture in non-lesional AD skin, filaggrin deficiency per se does not lead to the neutralization of skin surface pH or to excessive transepidermal water loss in atopic skin. Separating facts from chaff regarding the functions of filaggrin in the epidermis is necessary for the design efficacious therapies to treat dry and atopic skin.

Enhanced Activation of mTOR Signaling Pathway Was Found in the Hypertrophic and Nodular Lesions of Port Wine Stains

Background

Port wine stain (PWS) is a congenital skin lesion involving capillary malformations. Most PWS lesions will gradually become hypertrophic and appear nodular in contour. Current research shows that rapamycin, an mTOR inhibitor, is probably a promising adjunctive therapy for PWS, which suggests that the mTOR signaling pathway may play an important role in its pathological process.

Methods

From January 2013 to January 2019, 13 samples were obtained during the surgical excision. Each sample was divided into 3 parts according to the type of lesion, namely, the flat, hypertrophic and nodular lesions. Pathologic structures of each type were observed under the microscope after HE staining. The expression of mTORC1, p70S6, p-p70S6, eIF4EBP1 and p-eIF4EBP1 was examined by immunohistochemical staining and western blotting. The location of the expression of mTORC1, p-p70S6 and p-elF4EBP1 was further detected by immunofluorescence staining.

Results

Large amounts of dilated and malformed vessels were observed in all types of PWS lesions. Abundant hyperplastic hair follicles/glands were shown in the hypertrophic or nodular lesions. Phosphorylation level of p70S6 and elF4EBP1 in PWS was significantly higher than those in normal skin and increased accordingly in the progression of PWS. Activated molecules in mTOR signaling pathway were mostly located in the endothelium of malformed vessels. They were also located in the hyperplastic hair follicles/glands of hypertrophic and nodular lesions.

Conclusion

The mTOR signaling pathway was increasingly activated during the progression of PWS. Enhanced activation of mTOR signaling pathway may contribute to the hypertrophy and nodularity of PWS. The results provide preliminary evidence for treating PWS and related syndromes by inhibiting mTOR signaling pathway.

Ropivacaine inhibits wound healing by suppressing the proliferation and migration of keratinocytes via the PI3K/AKT/mTOR Pathway

Background

After surgery, millions of people suffer from delayed healing or wound dehiscence with subsequent severe complications, even death. Previous studies have reported that ropivacaine exhibits anti-proliferative and anti-migratory activities on numerous cells. Whether ropivacaine is able to influence the proliferation and migration of keratinocytes is still unclear. This study aimed to investigate the effect of ropivacaine on keratinocytes and its underlying molecular mechanism.

Methods

Adult male Sprague–Dawley rats were allocated to establish wound healing models with or without 0.75% ropivacaine treatment and assessed the epidermal thickness by HE staining. HaCaT cells were cultured to evaluate the effect of ropivacaine on wound healing. The cell proliferation, apoptosis status and migration were detected in vitro. Moreover, western blotting was used to examine expression to with PI3K/AKT/mTOR signaling pathways for molecular studies and the changes in inflammatory factors (IL-6, IL-10, TNF-α) were detected by ELISA.

Results

In the present study, we found that ropivacaine delayed wound closure in vivo. In vitro experiments, it was demonstrated that ropivacaine significantly inhibited the proliferation and migration of HaCaT cells via the suppression of PI3K/AKT/mTOR signaling pathway. Activation of PI3K/AKT/mTOR signaling pathway reversed the effects of ropivacaine on the proliferation and migration of HaCaT cells. Furthermore, ropivacaine contributed to the release of pro-inflammatory cytokines (IL-6 and TNF-α) and inhibited the secretion of anti-inflammatory cytokines of keratinocytes (IL-10).

Conclusions

Our research demonstrated that ropivacaine treatment showed a more decreased wound closure rate. Mechanistically, we found that ropivacaine suppressed the proliferation and migration of keratinocytes and altered the expression of cytokines by inhibiting PI3K/AKT/mTOR pathway.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12871-022-01646-0.

MiR-92a/KLF4/p110δ regulates titanium particles-induced macrophages inflammation and osteolysis

As total joint replacement is widely applied for severe arthropathy, peri-prosthetic aseptic loosening as one of the main causes of implant failure has drawn wide attention. Wear particles such as titanium particles (TiPs) derived from prosthesis can initiate macrophages inflammation and sequentially activate osteoclasts, which results in bone resorption and osteolysis for long-term. Therefore, inhibiting wear particles induced macrophages inflammation is considered as a promising therapy for AL. In this research, we found that the inhibition of p110δ, a member of class IA PI3Ks family, could significantly dampen the TiPs-induced secretion of TNFα and IL-6. By the transfection of siRNA targeting p110δ, we confirmed that p110δ was responsible for TNFα and IL-6 trafficking out of Golgi complex without affecting their expression in TiPs-treated macrophages. As the upstream transcription-repressor of p110δ, Krüppel-like factor 4 (KLF4), targeted by miR-92a, could also attenuate TiPs-induced inflammation by mediating NF-κB pathway and M1/M2 polarization. To further ascertain the roles of KLF4/p110δ, TiPs-induced mice cranial osteolysis model was established and vivo experiments validated that KLF4-knockdown could exacerbate TiPs-induced osteolysis, which was strikingly ameliorated by knockdown of p110δ. In summary, our study suggests the key role of miR-92a/KLF4/p110δ signal in TiPs-induced macrophages inflammation and osteolysis.

TLR4 polymorphisms as potential predictors of atopic dermatitis in Chinese Han children

Background

Toll‐like receptor 4 (TLR4) is considered to be involved in the pathogenesis and progression of atopic dermatitis (AD). In the present study, we evaluated the relationship between TLR4 gene polymorphisms and the susceptibility or severity of AD among Chinese Han children.

Methods

A total of 132 AD patients and 100 healthy controls were enrolled in this study. Four single‐nucleotide polymorphisms (rs19277914, rs11536891, rs7869402, and rs11536889) of the TLR4 gene were genotyped by multiplex PCR combined with next‐generation sequencing.

Results

Our results showed that a significantly reduced risk for AD was associated with C allele [p = 0.008; odds ratio (OR) = 0.41, C vs. T], TC genotype (p = 0.022; OR = 0.41, TC vs. TT), and TC + CC genotype (p = 0.010; OR = 0.39, TC + CC vs. TT) of TLR4 rs11536891. The frequency of the haplotype GCCG (rs1927914–rs11536891–rs7869402–rs11536889) in AD patients was lower than that in the controls (p = 0.010; OR = 0.38). Moreover, the results indicated that a higher risk of severe AD was related to the T allele (p = 0.019; OR = 2.97, T vs. C) and the TC genotype (p = 0.021; OR = 3.34, TC vs. CC) of TLR4 rs7869402. A risk haplotype of TLR4 (GTTG) was found in severe AD patients (p = 0.010; OR = 5.26).

Conclusions

Our data suggested that TLR4 rs11536891 polymorphism was associated with the susceptibility to AD in Chinese Han children. And TLR4 rs7869402 might confer the severity of pediatric AD patients.

Mitochondrial Metabolism in Melanoma

Melanoma and its associated alterations in cellular pathways have been growing areas of interest in research, especially as specific biological pathways are being elucidated. Some of these alterations include changes in the mitochondrial metabolism in melanoma. Many mitochondrial metabolic changes lead to differences in the survivability of cancer cells and confer resistance to targeted therapies. While extensive work has gone into characterizing mechanisms of resistance, the role of mitochondrial adaptation as a mode of resistance is not completely understood. In this review, we wish to explore mitochondrial metabolism in melanoma and how it impacts modes of resistance. There are several genes that play a major role in melanoma mitochondrial metabolism which require a full understanding to optimally target melanoma. These include BRAF, CRAF, SOX2, MCL1, TRAP1, RHOA, SRF, SIRT3, PTEN, and AKT1. We will be discussing the role of these genes in melanoma in greater detail. An enhanced understanding of mitochondrial metabolism and these modes of resistance may result in novel combinatorial and sequential therapies that may lead to greater therapeutic benefit.

PI3Kδ Sustains Keratinocyte Hyperproliferation and Epithelial Inflammation: Implications for a Topically Druggable Target in Psoriasis

The phosphatidylinositol 3-kinase (PI3K)-dependent signaling pathway is aberrantly activated in psoriatic lesions and contributes to disease pathogenesis. Among PI3Ks enzymes, PI3Kα, β, and δ isoforms are known to bind the p85 regulatory subunit and mediate activation of AKT and other downstream effectors. In this study, we deepened our understanding of the expression and function of PI3Kδ in skin lesions of patients affected by psoriasis. For the first time, we found that PI3Kδ is overexpressed in psoriatic plaques, and its expression is not only confined to infiltrating immune cells but also accumulates in proliferating keratinocytes of the epidermal basal layer. We investigated the function of PI3Kδ in psoriatic skin by evaluating the impact of seletalisib, a newly developed selective PI3Kδ inhibitor, in both in vitro and in vivo experimental models of psoriasis. Of note, we found that PI3Kδ sustains keratinocyte hyperproliferation and impaired terminal differentiation induced by IL-22, as well as induces epithelial inflammation and resistance to apoptosis mediated by TNF-α in human keratinocytes. Mechanistically, PI3Kδ promotes PDK1 phosphorylation and signals through AKT-dependent or -independent pathways. It is worth mentioning that PI3Kδ inhibition by seletalisib attenuates the severity of psoriasiform phenotype induced in the Imiquimod-induced mouse model of psoriasis by restoring the physiological proliferation and differentiation programs in epidermal keratinocytes and contrasting the cutaneous inflammatory responses. Therefore, we suggest PI3Kδ as a potential topically druggable target in psoriasis and skin diseases characterized by epidermal hyperproliferation and skin inflammation.

SLURP-1 Controls Growth and Migration of Lung Adenocarcinoma Cells, Forming a Complex With α7-nAChR and PDGFR/EGFR Heterodimer

Secreted Ly6/uPAR-related protein 1 (SLURP-1) is a secreted Ly6/uPAR protein that negatively modulates the nicotinic acetylcholine receptor of α7 type (α7-nAChR), participating in control of cancer cell growth. Previously we showed, that a recombinant analogue of human SLURP-1 (rSLURP-1) diminishes the lung adenocarcinoma A549 cell proliferation and abolishes the nicotine-induced growth stimulation. Here, using multiplex immunoassay, we demonstrated a decrease in PTEN and mammalian target of rapamycin (mTOR) kinase phosphorylation in A549 cells upon the rSLURP-1 treatment pointing on down-regulation of the PI3K/AKT/mTOR signaling pathway. Decreased phosphorylation of the platelet-derived growth factor receptor type β (PDGFRβ) and arrest of the A549 cell cycle in the S and G2/M phases without apoptosis induction was also observed. Using a scratch migration assay, inhibition of A549 cell migration under the rSLURP-1 treatment was found. Affinity extraction demonstrated that rSLURP-1 in A549 cells forms a complex not only with α7-nAChR, but also with PDGFRα and epidermal growth factor receptor (EGFR), which are known to be involved in regulation of cancer cell growth and migration and are able to form a heterodimer. Knock-down of the genes encoding α7-nAChR, PDGFRα, and EGFR confirmed the involvement of these receptors in the anti-migration effect of SLURP-1. Thus, SLURP-1 can target the α7-nAChR complexes with PDGFRα and EGFR in the membrane of epithelial cells. Using chimeric proteins with grafted SLURP-1 loops we demonstrated that loop I is the principal active site responsible for the SLURP-1 interaction with α7-nAChR and its antiproliferative effect. Synthetic peptide mimicking the loop I cyclized by a disulfide bond inhibited ACh-evoked current at α7-nAChR, as well as A549 cell proliferation and migration. This synthetic peptide represents a promising prototype of new antitumor drug with the properties close to that of the native SLURP-1 protein.

PI3K/AKT phosphorylation activates ERRα by upregulating PGC‑1α and PGC‑1β in gallbladder cancer

The nuclear estrogen‑related receptor‑α (ERRα) is an orphan receptor that has been identified as a transcriptional factor. Peroxisome proliferator‑activated receptor‑γ (PPARγ) coactivator‑1‑α (PGC‑1α) and PPARγ coactivator‑1‑β (PGC‑1β) act as the co‑activators of ERRα. Our previous study reported that activated ERRα promoted the invasion and proliferation of gallbladder cancer cells by promoting PI3K/AKT phosphorylation. Therefore, the aim of the current study was to investigate whether PI3K/AKT phosphorylation could enhance ERRα activity in a positive feedback loop. LY294002 and insulin‑like growth factor I (IGF‑I) were used to inhibit and promote PI3K/AKT phosphorylation, respectively. A 3X ERE‑TATA luciferase reporter was used to measure ERRα activity. The present study found that LY294002 inhibited PI3K/AKT phosphorylation, decreased the proliferation and invasion of NOZ cells and suppressed the activity of ERRα. Conversely, IGF‑I induced PI3K/AKT phosphorylation, promoted the proliferation and invasion of NOZ cells and enhanced the activity of ERRα. The protein expression levels of PGC‑1α and PGC‑1β were elevated and reduced by IGF‑I and LY294002, respectively. Moreover, knockdown of PGC‑1α and PGC‑1β antagonized ERRα activation, which was enhanced by PI3K/AKT phosphorylation. Taken together, the present study demonstrated that PI3K/AKT phosphorylation triggered ERRα by upregulating the expression levels of PGC‑1α and PGC‑1β in NOZ cells.

PI3K/AKT phosphorylation activates ERRα by upregulating PGC‑1α and PGC‑1β in gallbladder cancer

The nuclear estrogen‑related receptor‑α (ERRα) is an orphan receptor that has been identified as a transcriptional factor. Peroxisome proliferator‑activated receptor‑γ (PPARγ) coactivator‑1‑α (PGC‑1α) and PPARγ coactivator‑1‑β (PGC‑1β) act as the co‑activators of ERRα. Our previous study reported that activated ERRα promoted the invasion and proliferation of gallbladder cancer cells by promoting PI3K/AKT phosphorylation. Therefore, the aim of the current study was to investigate whether PI3K/AKT phosphorylation could enhance ERRα activity in a positive feedback loop. LY294002 and insulin‑like growth factor I (IGF‑I) were used to inhibit and promote PI3K/AKT phosphorylation, respectively. A 3X ERE‑TATA luciferase reporter was used to measure ERRα activity. The present study found that LY294002 inhibited PI3K/AKT phosphorylation, decreased the proliferation and invasion of NOZ cells and suppressed the activity of ERRα. Conversely, IGF‑I induced PI3K/AKT phosphorylation, promoted the proliferation and invasion of NOZ cells and enhanced the activity of ERRα. The protein expression levels of PGC‑1α and PGC‑1β were elevated and reduced by IGF‑I and LY294002, respectively. Moreover, knockdown of PGC‑1α and PGC‑1β antagonized ERRα activation, which was enhanced by PI3K/AKT phosphorylation. Taken together, the present study demonstrated that PI3K/AKT phosphorylation triggered ERRα by upregulating the expression levels of PGC‑1α and PGC‑1β in NOZ cells.