Neurokinin-1 receptor is a novel positive regulator of Wnt/ β-catenin signaling in melanogenesis

Small Peptide Derived from SFRP5 Suppresses Melanogenesis by Inhibiting Wnt Activity

Melanocytes, located in the epidermis' basal layer, are responsible for melanin pigment production, crucial for skin coloration and protection against UV radiation-induced damage. Melanin synthesis is intricately regulated by various factors, including the Wnt signaling pathway, particularly mediated by the microphthalmia-associated transcription factor (MITF). While MITF is recognized as a key regulator of pigmentation, its regulation by the Wnt pathway remains poorly understood. This study investigates the role of Sfrp5pepD, a peptide antagonist of the Wnt signaling pathway, in modulating melanogenesis and its potential therapeutic implications for pigmentary disorders. To tackle this issue, we investigated smaller peptides frequently utilized in cosmetics or pharmaceuticals. Nevertheless, there is a significant scarcity of reports on peptides associated with melanin-related signal modulation or inhibiting melanin production. Results indicate that Sfrp5pepD effectively inhibits Wnt signaling by disrupting the interaction between Axin-1 and β-catenin, thus impeding downstream melanogenic processes. Additionally, Sfrp5pepD suppresses the interaction between MITF and β-catenin, inhibiting their nuclear translocation and downregulating melanogenic enzyme expression, ultimately reducing melanin production. These inhibitory effects are validated in cell culture models suggesting potential clinical applications for hyperpigmentation disorders. Overall, this study elucidates the intricate interplay between Wnt signaling and melanogenesis, highlighting Sfrp5pepD as a promising therapeutic agent for pigmentary disorders. Sfrp5pepD, with a molecular weight of less than 500 Da, is anticipated to penetrate the skin unlike SFRPs. This suggests a strong potential for their use as cosmetics or transdermal absorption agents. Additional investigation into its mechanisms and clinical significance is necessary to enhance its effectiveness in addressing melanin-related skin conditions.

The Repurposing of Non-Peptide Neurokinin-1 Receptor Antagonists as Antitumor Drugs: An Urgent Challenge for Aprepitant

The substance P (SP)/neurokinin-1 receptor (NK-1R) system is involved in cancer progression. NK-1R, activated by SP, promotes tumor cell proliferation and migration, angiogenesis, the Warburg effect, and the prevention of apoptosis. Tumor cells overexpress NK-1R, which influences their viability. A typical specific anticancer strategy using NK-1R antagonists, irrespective of the tumor type, is possible because these antagonists block all the effects mentioned above mediated by SP on cancer cells. This review will update the information regarding using NK-1R antagonists, particularly Aprepitant, as an anticancer drug. Aprepitant shows a broad-spectrum anticancer effect against many tumor types. Aprepitant alone or in combination therapy with radiotherapy or chemotherapy could reduce the sequelae and increase the cure rate and quality of life of patients with cancer. Current data open the door to new cancer research aimed at antitumor therapeutic strategies using Aprepitant. To achieve this goal, reprofiling the antiemetic Aprepitant as an anticancer drug is urgently needed.

Reversing Gray Hair: Inspiring the Development of New Therapies Through Research on Hair Pigmentation and Repigmentation Progress

Hair graying is a common and visible sign of aging resulting from decreased or absence of melanogenesis. Although it has been established that gray hair greatly impacts people's mental health and social life, there is no effective countermeasure other than hair dyes. It has long been thought that reversal of gray hair on a large scale is rare. However, a recent study reported that individual gray hair darkening is a common phenomenon, suggesting the possibility of large-scale reversal of gray hair. In this article, we summarize the regulation mechanism of melanogenesis and review existing cases of hair repigmentation caused by several factors, including monoclonal antibodies drugs, tyrosine kinase inhibitors (TKIs), immunomodulators, other drugs, micro-injury, and tumors, and speculate on the mechanisms behind them. This review offers some insights for further research into the modulation of melanogenesis and presents a novel perspective on the development of clinical therapies, with emphasis on topical treatments.

A Comprehensive Review of Mammalian Pigmentation: Paving the Way for Innovative Hair Colour-Changing Cosmetics

The natural colour of hair shafts is formed at the bulb of hair follicles, and it is coupled to the hair growth cycle. Three critical processes must happen for efficient pigmentation: (1) melanosome biogenesis in neural crest-derived melanocytes, (2) the biochemical synthesis of melanins (melanogenesis) inside melanosomes, and (3) the transfer of melanin granules to surrounding pre-cortical keratinocytes for their incorporation into nascent hair fibres. All these steps are under complex genetic control. The array of natural hair colour shades are ascribed to polymorphisms in several pigmentary genes. A myriad of factors acting via autocrine, paracrine, and endocrine mechanisms also contributes for hair colour diversity. Given the enormous social and cosmetic importance attributed to hair colour, hair dyeing is today a common practice. Nonetheless, the adverse effects of the long-term usage of such cosmetic procedures demand the development of new methods for colour change. In this context, case reports of hair lightening, darkening and repigmentation as a side-effect of the therapeutic usage of many drugs substantiate the possibility to tune hair colour by interfering with the biology of follicular pigmentary units. By scrutinizing mammalian pigmentation, this review pinpoints key targetable processes for the development of innovative cosmetics that can safely change the hair colour from the inside out.

Steroidogenic cell microenvironment and adrenal function in physiological and pathophysiological conditions

The human adrenal cortex is a complex organ which is composed of various cell types including not only steroidogenic cells but also mesenchymal cells, immunocompetent cells and neurons. Intermingling of these diverse cell populations favors cell-to-cell communication processes involving local release of numerous bioactive signals such as biogenic amines, cytokines and neuropeptides. The resulting paracrine interactions play an important role in the regulation of adrenocortical cell functions both in physiological and pathophysiological conditions. Especially, recent evidence indicates that adrenocortical cell microenvironment is involved in the pathogenesis of adrenal disorders associated with corticosteroid excess. The paracrine factors involved in these intraadrenal regulatory mechanisms may thus represent valuable targets for future pharmacological treatments of adrenal diseases.

The emerging role of substance P/neurokinin-1 receptor signaling pathways in growth and development of tumor cells

Tachykinins (TKs) include an evolutionarily conserved group of small bio-active peptides which possess a common carboxyl-terminal sequence, Phe-X-Gly-Leu-Met-NH2. TKs also have been shown to have implications in different steps of carcinogenesis, such as angiogenesis, mitogenesis, metastasis, and other growth-related events. The biological actions of substance P (SP), as the most important member of the TK family, are mainly mediated through a G protein-coupled receptor named neurokinin-1 receptor (NK1R). More recently, it has become clear that SP/NK1R system is involved in the initiation and activation of signaling pathways involved in cancer development and progression. Therefore, SP may contribute to triggering a variety of effector mechanisms including protein synthesis and a number of transcription factors that modulate the expression of genes involved in these processes. The overwhelming insights into the blockage of NK1R using specific antagonists could suggest a therapeutic approach in cancer therapy. In this review, we focus on evidence supporting an association between the signaling pathways of the SP/NK1R system and cancer cell proliferation and development.

MicroRNA-1-3p inhibits the proliferation and migration of oral squamous cell carcinoma cells by targeting DKK1

We investigated the functional role and mechanism of miR-1-3p and DKK1 in oral squamous cell carcinoma (OSCC) cells. The level of miR-1-3p and DKK1 expression were detected in OSCC tissues and cells using reverse-transcription - quantitative PCR and Western blot. A dual luciferase reporter gene assay was applied to confirm the targeting relationship between miR-1-3p and DKK1. Functional assays, including MTT, Transwell, colony formation, and flow cytometry analysis were conducted to verify their effect on cell progressions. MTT, colony formation, and Transwell assays indicated that the proliferation, migration, and invasion of SCC-4 cells was impaired with high miR-1-3p expression but promoted with high DKK1 expression. The results from cell cycle analysis and annexin-V-PI assays for apoptosis suggested that miR-1-3p suppressed the transit of SCC-4 cells from G0/G1 to S and induced apoptosis. In summary, miR-1-3p suppressed the progression of OSCC by inhibiting DKK1 expression.

Suppression of miR-708 inhibits the Wnt/β-catenin signaling pathway by activating DKK3 in adult B-all

Inactivation of Dickkopf-3 (DKK3) is closely associated with a poor prognosis in various solid tumor and hematologic malignancies. Promoter hypermethylation is one potential cause of DKK3 inactivation. However, whether other mechanisms lead to DKK3 inactivation and the subsequent effects of these inactivations on cell proliferation and the Wnt signaling pathway in adult B acute lymphoblastic leukemia (B-ALL) remain unclear. In the present study, we found that low DKK3 expression levels were associated with high miR-708 expression and promoter hypermethylation in adult B-ALL. miR-708 was confirmed to directly decrease DKK3 expression in Nalm-6 and BALL-1 cells. Additionally, a miR-708 inhibitor decreased cell proliferation mainly through apoptosis and cell cycle arrest at the G1 phase, and these effects were eliminated by DKK3 siRNA treatment. Moreover, the demethylating agent 5-aza-2'-deoxycytidine (5-aza) decreased the methylation state of the DKK3 promoter based on methylation-specific PCR (MSP) and bisulfite genomic sequencing PCR (BSP), although this demethylation effect was not enhanced by the miR-708 inhibitor. The miR-708 inhibitor or 5-aza significantly increased DKK3 expression and decreased p-GSK3β, cyclin D1 and nuclear and cytoplasmic β-catenin protein expression, indicating that the Wnt/β-catenin signaling pathway was inhibited. These effects became more pronounced when the miR-708 inhibitor and 5-aza were used simultaneously. These findings provide greater insights into the mechanisms that increase DKK3 expression and suggest that a miR-708 inhibitor and 5-aza might be useful as targeted therapies for adult B-ALL.