Ultraviolet B irradiation enhances the secretion of exosomes by human primary melanocytes and changes their exosomal miRNA profile

Novel Exosomal miRNA Expression in Irradiated Human Keratinocytes

The epidermis, the outer layer of the skin, relies on a delicate balance of cell growth and keratinocyte differentiation for its function and renewal. Recent research has shed light on exosomes' role in facilitating skin communication by transferring molecules like miRNAs, which regulate gene expression post-transcriptionally. Additionally, these factors lead to skin aging through oxidative stress caused by reactive oxygen species (ROS). In this research project, experiments were conducted to study the impact of Sun2000 solar simulator irradiation on exosomal miRNA profiles in HEKa cells. We hypothesized that acute oxidative stress induced by solar simulator irradiation would alter the expression profile of exosomal miRNAs in HEKa cells. The cells were exposed to different durations of irradiation to induce oxidative stress, and the levels of reactive ROS were measured using the CellROX Deep Red flow cytometry assay kit. Exosomes were isolated from both control and irradiated cells, characterized using DLS and SEM techniques, and their miRNAs were extracted and analyzed using qPCR. Solar simulator irradiation led to a time-dependent increase in intracellular ROS and a decrease in cell viability. Exosomal size increased in irradiated cells. Fifty-nine exosomal miRNAs were differentially expressed in irradiated HEKa cells, including hsa-miR-425-5p, hsa-miR-181b-5p, hsa-miR-196b-5p, hsa-miR-376c-3p, and hsa-miR-15a-5p. This study highlights the significant impact of solar radiation on exosomal miRNA expression in keratinocytes, suggesting their potential role in the cellular response to oxidative stress.

Role of non‑coding RNAs in UV‑induced radiation effects (Review)

Ultraviolet (UV) is divided into UVA (long-wave, 320-400 nm), UVB (middle-wave, 280-320 nm) and UVC (short-wave, 100-280 nm) based on wavelength. UV radiation (UVR) from sunlight (UVA + UVB) is a major cause of skin photodamage including skin inflammation, aging and pigmentation. Accidental exposure to UVC burns the skin and induces skin cancer. In addition to the skin, UV radiation can also impair visual function. Non-coding RNAs (ncRNAs) are a class of functional RNAs that do not have coding activity but can control cellular processes at the post-transcriptional level, including microRNA (miRNA), long non-coding RNA (lncRNA) and circulatory RNA (circRNA). Through a review of the literature, it was determined that UVR can affect the expression of various ncRNAs, and that this regulation may be wavelength specific. Functionally, ncRNAs participate in the regulation of photodamage through various pathways and play pathogenic or protective regulatory roles. In addition, ncRNAs that are upregulated or downregulated by UVR can serve as biomarkers for UV-induced diseases, aiding in diagnosis and prognosis assessment. Therapeutic strategies targeting ncRNAs, including the use of natural drugs and their extracts, have shown protective effects against UV-induced photodamage. In the present review, an extensive summarization of previous studies was performed and the role and mechanism of ncRNAs in UV-induced radiation effects was reviewed to aid in the diagnosis and treatment of UV-related diseases.

Enrichment, Characterization, and Proteomic Profiling of Small Extracellular Vesicles Derived from Human Limbal Mesenchymal Stromal Cells and Melanocytes

Limbal epithelial progenitor cells (LEPC) rely on their niche environment for proper functionality and self-renewal. While extracellular vesicles (EV), specifically small EVs (sEV), have been proposed to support LEPC homeostasis, data on sEV derived from limbal niche cells like limbal mesenchymal stromal cells (LMSC) remain limited, and there are no studies on sEVs from limbal melanocytes (LM). In this study, we isolated sEV from conditioned media of LMSC and LM using a combination of tangential flow filtration and size exclusion chromatography and characterized them by nanoparticle tracking analysis, transmission electron microscopy, Western blot, multiplex bead arrays, and quantitative mass spectrometry. The internalization of sEV by LEPC was studied using flow cytometry and confocal microscopy. The isolated sEVs exhibited typical EV characteristics, including cell-specific markers such as CD90 for LMSC-sEV and Melan-A for LM-sEV. Bioinformatics analysis of the proteomic data suggested a significant role of sEVs in extracellular matrix deposition, with LMSC-derived sEV containing proteins involved in collagen remodeling and cell matrix adhesion, whereas LM-sEV proteins were implicated in other cellular bioprocesses such as cellular pigmentation and development. Moreover, fluorescently labeled LMSC-sEV and LM-sEV were taken up by LEPC and localized to their perinuclear compartment. These findings provide valuable insights into the complex role of sEV from niche cells in regulating the human limbal stem cell niche.

Effect of environmental exposures on cancer risk: Emerging role of non-coding RNA shuttled by extracellular vesicles

Environmental and lifestyle exposures have a huge impact on cancer risk; nevertheless, the biological mechanisms underlying this association remain poorly understood. Extracellular vesicles (EVs) are membrane-enclosed particles actively released by all living cells, which play a key role in intercellular communication. EVs transport a variegate cargo of biomolecules, including non-coding RNA (ncRNA), which are well-known regulators of gene expression. Once delivered to recipient cells, EV-borne ncRNAs modulate a plethora of cancer-related biological processes, including cell proliferation, differentiation, and motility. In addition, the ncRNA content of EVs can be altered in response to outer stimuli. Such changes can occur either as an active attempt to adapt to the changing environment or as an uncontrolled consequence of cell homeostasis loss. In either case, such environmentally-driven alterations in EV ncRNA might affect the complex crosstalk between malignant cells and the tumor microenvironment, thus modulating the risk of cancer initiation and progression. In this review, we summarize the current knowledge about EV ncRNAs at the interface between environmental and lifestyle determinants and cancer. In particular, we focus on the effect of smoking, air and water pollution, diet, exercise, and electromagnetic radiation. In addition, we have conducted a bioinformatic analysis to investigate the biological functions of the genes targeted by environmentally-regulated EV microRNAs. Overall, we draw a comprehensive picture of the role of EV ncRNA at the interface between external factors and cancer, which could be of great interest to the development of novel strategies for cancer prevention, diagnosis, and therapy.

miR-656-3p inhibits melanomas in vitro and in vivo by inducing senescence via inhibiting LMNB2

BACKGROUND

Ultra-Violet Radiation (UVR) is the most significant exogenous contributor to skin aging. UVB causes the senescence of melanocytes, which results in a permanent arrest in the proliferative process. Senescence is also regarded as a physiological tumor-suppressing mechanism of normal cells. However, the mechanism of the relationship between melanocyte senescence and melanoma was not sufficiently clarified.

METHODS

Melanocytes and melanoma cells were irradiated with UVB for the indicated time. The miRNA expression profile of melanocytes were obtained by miRNA sequencing and confirmed by real-time PCR. Cell count kit-8 assays, cell cycle assays were also employed to explore the effect of miR-656-3p and LMNB2 on senescence. Dual-luciferase reporter assays were applied to determine the miRNA targets. Finally, a xenograft model and a photoaging model of mice were conducted to verified the function of miR-656-3p in vivo.

RESULTS

Melanoma cells did not alter into a senescence stage and the expressions of miR-656-3p had no significant changes under the same intensity of UVB radiation. miR-656-3p appeared to be upregulated in melanocytes rather than melanoma cells after UVB radiation. miR-656-3p could promote the photoaging of human primary melanocytes by targeting LMNB2. Finally, overexpression of miR-656-3p significantly induced senescence and inhibited the growth of melanomas in vitro and in vivo.

CONCLUSION

Our work not only demonstrated the mechanism by which miR-656-3p induced the senescence of melanocytes but also proposed a treatment strategy for melanomas by using miR-656-3p to induce senescence.

Enhancing the Cellular Production of Extracellular Vesicles for Developing Therapeutic Applications

Extracellular vesicles (EVs) have various advantageous properties, including a small size, high biocompatibility, efficient cargo loading, and precise cell targeting ability, making them promising tools for therapeutic development. EVs have been increasingly explored for applications like drug delivery. However, due to limited cellular secretion rates of EVs, wide-scale clinical applications are not achievable. Therefore, substantial strategies and research efforts have been devoted to increasing cellular secretion rates of EVs. This review describes various studies exploring different methods to increase the cellular production of EVs, including the application of electrical stimulus, pharmacologic agents, electromagnetic waves, sound waves, shear stress, cell starvation, alcohol, pH, heat, and genetic manipulation. These methods have shown success in increasing EV production, but careful consideration must be given as many of these strategies may alter EV properties and functionalities, and the exact mechanisms causing the increase in cellular production of EVs is generally unknown. Additionally, the methods' effectiveness in increasing EV secretion may diverge with different cell lines and conditions. Further advancements to enhance EV biogenesis secretion for therapeutic development is still a significant need in the field.

The retinal pigmentation pathway in human albinism: Not so black and white

Albinism is a pigment disorder affecting eye, skin and/or hair. Patients usually have decreased melanin in affected tissues and suffer from severe visual abnormalities, including foveal hypoplasia and chiasmal misrouting. Combining our data with those of the literature, we propose a single functional genetic retinal signalling pathway that includes all 22 currently known human albinism disease genes. We hypothesise that defects affecting the genesis or function of different intra-cellular organelles, including melanosomes, cause syndromic forms of albinism (Hermansky-Pudlak (HPS) and Chediak-Higashi syndrome (CHS)). We put forward that specific melanosome impairments cause different forms of oculocutaneous albinism (OCA1-8). Further, we incorporate GPR143 that has been implicated in ocular albinism (OA1), characterised by a phenotype limited to the eye. Finally, we include the SLC38A8-associated disorder FHONDA that causes an even more restricted "albinism-related" ocular phenotype with foveal hypoplasia and chiasmal misrouting but without pigmentation defects. We propose the following retinal pigmentation pathway, with increasingly specific genetic and cellular defects causing an increasingly specific ocular phenotype: (HPS1-11/CHS: syndromic forms of albinism)-(OCA1-8: OCA)-(GPR143: OA1)-(SLC38A8: FHONDA). Beyond disease genes involvement, we also evaluate a range of (candidate) regulatory and signalling mechanisms affecting the activity of the pathway in retinal development, retinal pigmentation and albinism. We further suggest that the proposed pigmentation pathway is also involved in other retinal disorders, such as age-related macular degeneration. The hypotheses put forward in this report provide a framework for further systematic studies in albinism and melanin pigmentation disorders.

Exosomes released by melanocytes modulate fibroblasts to promote keloid formation: a pilot study

Keloids are a common type of pathological scar as a result of skin healing, which are extremely difficult to prevent and treat without recurrence. The pathological mechanism of keloids is the excessive proliferation of fibroblasts, which synthesize more extracellular matrices (ECMs), including type I/III collagen (COL-1/3), mucopolysaccharides, connective tissue growth factor (CTGF, also known as cellular communication network factor 2 (CCN2)), and fibronectin (FN) in scar tissue, mostly through the abnormal activation of transforming growth factor-‍β (TGF-‍β)/Smads pathway (Finnson et al., 2013; Song et al., 2018). Genetic factors, including race and skin tone, are considered to contribute to keloid formation. The reported incidence of keloids in black people is as high as 16%, whereas white people are less affected. The prevalence ratio of colored people to white people is 5:1‍‍-‍‍15:1 (Rockwell et al., 1989; LaRanger et al., 2019). In addition, keloids have not been reported in albinism patients of any race, and those with darker skin in the same race are more likely to develop this disease (LaRanger et al., 2019). Skin melanocyte activity is significantly different among people with different skin tones. The more active the melanocyte function, the more melanin is produced and the darker the skin. Similarly, in the same individual, the incidence of keloids increases during periods when melanocytes are active, such as adolescence and pregnancy. Keloids rarely appear in areas where melanocytes synthesize less melanin, such as in the palms and soles. Thus, the formation of keloids seems to be closely related to melanocyte activity.

Integrative small and long RNA omics analysis of human healing and nonhealing wounds discovers cooperating microRNAs as therapeutic targets

MicroRNAs (miR), as important epigenetic control factors, reportedly regulate wound repair. However, our insufficient knowledge of clinically relevant miRs hinders their potential therapeutic use. For this, we performed paired small and long RNA-sequencing and integrative omics analysis in human tissue samples, including matched skin and acute wounds collected at each healing stage and chronic nonhealing venous ulcers (VUs). On the basis of the findings, we developed a compendium (https://www.xulandenlab.com/humanwounds-mirna-mrna), which will be an open, comprehensive resource to broadly aid wound healing research. With this first clinical, wound-centric resource of miRs and mRNAs, we identified 17 pathologically relevant miRs that exhibited abnormal VU expression and displayed their targets enriched explicitly in the VU gene signature. Intermeshing regulatory networks controlled by these miRs revealed their high cooperativity in contributing to chronic wound pathology characterized by persistent inflammation and proliferative phase initiation failure. Furthermore, we demonstrated that miR-34a, miR-424, and miR-516, upregulated in VU, cooperatively suppressed keratinocyte migration and growth while promoting inflammatory response. By combining miR expression patterns with their specific target gene expression context, we identified miRs highly relevant to VU pathology. Our study opens the possibility of developing innovative wound treatment that targets pathologically relevant cooperating miRs to attain higher therapeutic efficacy and specificity.

Extracellular Vesicles and Hepatocellular Carcinoma: Opportunities and Challenges

The incidence of hepatocellular carcinoma (HCC) is increasing worldwide. Extracellular vesicles (EVs) contain sufficient bioactive substances and are carriers of intercellular information exchange, as well as delivery vehicles for nucleic acids, proteins and drugs. Although EVs show great potential for the treatment of HCC and their role in HCC progression has been extensively studied, there are still many challenges such as time-consuming extraction, difficult storage, easy contamination, and low drug loading rate. We focus on the biogenesis, morphological characteristics, isolation and extraction of EVs and their significance in the progression of HCC, tumor invasion, immune escape and cancer therapy for a review. EVs may be effective biomarkers for molecular diagnosis of HCC and new targets for tumor-targeted therapy.

An estimate of extracellular vesicle secretion rates of human blood cells

Extracellular vesicles (EVs) have been implicated in the intercellular transfer of RNA and proteins through cellular secretion into the extracellular space. In blood plasma, circulating EVs are mainly derived from blood cells; however, factors that control plasma EV abundance are largely unknown. Here, we estimate the EV secretion rates for blood cell types using reported values for cell-specific plasma EV abundances and their parental cell's ubiquity in healthy humans. While we found that plasma contains on average ∼2 plasma EVs/cell, the cell-specific EV-to-cell ratio spanned four orders of magnitude from 0.13 ± 0.1 erythrocyte-derived EVs/erythrocyte to (1.9 ± 1.3) × 103 monocyte-derived EVs/monocyte. The steady-state plasma EV level was maintained by an estimated plasma EV secretion rate of (1.5 ± 0.4) ×  1012 EVs/min. The cell-specific secretion rate estimates were highest for monocytes (45 ± 21 EVs/cell/min) and lowest for erythrocytes ((3.2 ± 3.0) ×  10-3 EVs/cell/min). The estimated basal cell-specific EV secretion rates were not significantly correlated to the cell's lifespan or size; however, we observed a highly significant correlation to cellular mitochondrial enzyme activities. Together, our analysis indicates that cell-specific mitochondrial metabolism, for example, via reactive oxygen species, affects plasma EV abundance through increased secretion rates, and the results provide a resource for understanding EV function in human health and disease.

Light-induced high-efficient cellular production of immune functional extracellular vesicles

Extracellular vesicle (EV)-based therapies and vaccines are emerging. However, employment at the scale for population-based dose development is always a huge bottleneck. In order to overcome such a roadblock, we introduce a simple and straightforward approach for promoting cellular production of dendritic cell derived EVs (DEVs) by leveraging phototherapy based light induction. Under the optimization of light wavelengths, intensities, and exposure times, we achieved more than 13-fold enhancement in DEV production rate, while maintaining good integral quality and immune function from produced EVs. The LED light at 365 nm is optimal to reliably trigger enhanced cellular production of EVs no matter cell line types. Our observation and other reported studies support longer near UV wavelength does not impair cell growth. We conducted a series of investigations in terms of size, zeta potential, morphology, immune surface markers and cytokines, biocompatibility, cellular uptake behaviour, and immune-modulation ability on eliciting cellular responses in vitro. We also validated the biodistribution, immunogenicity, and administration safety using light-promoted DEVs in mice models from both male and female genders. Overall data supports that light promoted DEVs are highly immune functional with great biocompatibility for serving as good therapeutic platforms. The in vivo animal study also demonstrated light-promoted DEVs are as well tolerated as native DEVs, with no safety concerns. Taken together, the data supports that light promoted DEVs are in excellent quality, high biocompatibility, in vivo tolerant, and viable for serving as an ideal therapeutic platform in scalable production.

Therapeutic implications of exosomes in the treatment of radiation injury

Radiotherapy is one of the main cancer treatments, but it may damage normal tissue and cause various side effects. At present, radioprotective agents used in clinics have side effects such as nausea, vomiting, diarrhea and hypotension, which limit their clinical application. It has been found that exosomes play an indispensable role in radiation injury. Exosomes are lipid bilayer vesicles that carry various bioactive substances, such as proteins, lipids and microRNA (miRNA), that play a key role in cell-to-cell communication and affect tissue injury and repair. In addition, studies have shown that radiation can increase the uptake of exosomes in cells and affect the composition and secretion of exosomes. Here, we review the existing studies and discuss the effects of radiation on exosomes and the role of exosomes in radiation injury, aiming to provide new insights for the treatment of radiation injury.

Secretory Autophagy Forges a Therapy Resistant Microenvironment in Melanoma

Melanoma is the most aggressive skin cancer characterized by high mutational burden and large heterogeneity. Cancer cells are surrounded by a complex environment, critical to tumor establishment and progression. Thus, tumor-associated stromal components can sustain tumor demands or impair cancer cell progression. One way to manage such processes is through the regulation of autophagy, both in stromal and tumor cells. Autophagy is a catabolic mechanism that provides nutrients and energy, and it eliminates damaged organelles by degradation and recycling of cellular elements. Besides this primary function, autophagy plays multiple roles in the tumor microenvironment capable of affecting cell fate. Evidence demonstrates the existence of novel branches in the autophagy system related to cytoplasmic constituent's secretion. Hence, autophagy-dependent secretion assembles a tangled network of signaling that potentially contributes to metabolism reprogramming, immune regulation, and tumor progression. Here, we summarize the current awareness regarding secretory autophagy and the intersection with exosome biogenesis and release in melanoma and their role in tumor resistance. In addition, we present and discuss data from public databases concerning autophagy and exosome-related genes as important mediators of melanoma behavior. Finally, we will present the main challenges in the field and strategies to translate most of the pre-clinical findings to clinical practice.

Extracellular Vesicles: Footprints of environmental exposures in the aging process?

PURPOSE OF THE REVIEW

Extracellular vesicles (EVs) are nano-sized lipid particles that participate in intercellular signaling through the trafficking of bioactive molecules from parental cells to recipient ones. This well-orchestrated communication system is crucial for the organism to respond to external cues in a coordinated manner; indeed, environmental and lifestyle exposures can modify both EV number and content, with consequences on cellular metabolism and homeostasis. In particular, a growing body of evidence suggests that exposome-induced changes in EV profile could regulate the aging process, both at the cellular and organismal levels. Here, we provide an overview of the role played by ambient-induced EVs on aging and age-related diseases. Among the several environmental factors that can affect the communication network operated by EVs, we focused on air pollution, ultraviolet light, diet, and physical exercise. Moreover, we performed a miRNA target analysis, to support the role of EV-miRNA emerging from the literature in the context of aging.

RECENT FINDINGS

The overall emerging picture strongly supports a key regulatory role for EVs at the interface between external stimuli and cellular/organismal aging, thus providing novel insights into the molecular mechanisms linking a "healthy exposome" to well-being in old age. In addition, this knowledge will pave the way for research aimed at developing innovative antiaging strategies based on EVs.

Home and Away: The Role of Non-Coding RNA in Intracellular and Intercellular DNA Damage Response

Non-coding RNA (ncRNA) has recently emerged as a vital component of the DNA damage response (DDR), which was previously believed to be solely regulated by proteins. Many species of ncRNA can directly or indirectly influence DDR and enhance DNA repair, particularly in response to double-strand DNA breaks, which may hold therapeutic potential in the context of cancer. These include long non-coding RNA (lncRNA), microRNA, damage-induced lncRNA, DNA damage response small RNA, and DNA:RNA hybrid structures, which can be categorised as cis or trans based on the location of their synthesis relative to DNA damage sites. Mechanisms of RNA-dependent DDR include the recruitment or scaffolding of repair factors at DNA break sites, the regulation of repair factor expression, and the stabilisation of repair intermediates. DDR can also be communicated intercellularly via exosomes, leading to bystander responses in healthy neighbour cells to generate a population-wide response to damage. Many microRNA species have been directly implicated in the propagation of bystander DNA damage, autophagy, and radioresistance, which may prove significant for enhancing cancer treatment via radiotherapy. Here, we review recent developments centred around ncRNA and their contributions to intracellular and intercellular DDR mechanisms.

New insights into exosome mediated tumor-immune escape: Clinical perspectives and therapeutic strategies

Recent advances in extracellular vesicle biology have uncovered a substantial role in maintaining cell homeostasis in health and disease conditions by mediating intercellular communication, thus catching the scientific community's attention worldwide. Extracellular microvesicles, some called exosomes, functionally transfer biomolecules such as proteins and non-coding RNAs from one cell to another, influencing the local environment's biology. Although numerous advancements have been made in treating cancer patients with immune therapy, controlling the disease remains a challenge in the clinic due to tumor-driven interference with the immune response and inability of immune cells to clear cancer cells from the body. The present review article discusses the recent findings and knowledge gaps related to the role of exosomes derived from tumors and the tumor microenvironment cells in tumor escape from immunosurveillance. Further, we highlight examples where exosomal non-coding RNAs influence immune cells' response within the tumor microenvironment and favor tumor growth and progression. Therefore, exosomes can be used as a therapeutic target for the treatment of human cancers.