Reactive Oxygen Species Regulation of Chemoresistance and Metastatic Capacity of Melanoma: Role of the Cancer Stem Cell Marker CD271

Neurotoxic effects of coronavirus: Potential implications in Alzheimer's onset and progression

The COVID-19, caused by SARS-CoV-2, first affects the respiratory tract but evidence is emerging that the virus, reaching the central nervous system (CNS), can lead to severe neurological disorders. In particular, CoV infection could cause an acceleration of the neurodegenerative process. On the other hand, patients diagnosed with Alzheimer's disease (AD) develop more serious forms of COVID-19 with worse relapses. Therefore, understanding the connection between the two pathologies, AD and infection by coronavirus, could help in the development of new therapeutic approaches to counter them. We used the SH-SY5Y cell line differentiated into neurons, as widely used in studies of AD if supplemented with exogenous fibrillary β-amyloid (Aβ). As a glial counterpart, human microglia (HMC3) and astrocytic (D54MG) cell lines were used to create co-cultures with neurons via transwell systems. In these experimental models, we generated infection with the Human Coronavirus OC43 (HCoV-OC43), a low-risk model of SARS-CoV-2. Our results suggest that the infection by HCoV-OC43 leads to a neurotoxic effect not depending on an already present event of Aβ deposition. Indeed, unlike microglia, neurons and even more astrocytes are susceptible to CoV infection and, although the infection does not show a cytotoxic effect in the neurons in the first few days, significant alterations at a biochemical and morphological level have been observed, suggesting that the neurons are reacting to a stressful condition, including the prodromal and neurodegenerative features of AD. Interestingly, the interaction of infected astrocytes with the neurons resulted in the manifestation of signs of neurodegeneration, such as amyloid-beta deposition. By using exogenous fibrillary Aβ, as an AD in vitro model, our data suggest that there is an aggravating effect both on the infection itself and on the neurological disease progression. In conclusion, the results of this study suggest a causal interplay between HCoV-OC43 and neurological diseases and demonstrate that the co-presence of different CNS cell populations is the necessary condition to study the pathogenic effects in vitro as a whole.

Promotion of apoptosis in melanoma cells by taxifolin through the PI3K/AKT signaling pathway: Screening of natural products using WGCNA and CMAP platforms

Melanoma is a skin cancer originating from melanocytes. The global incidence rate of melanoma is rapidly increasing, posing significant public health challenges. Identifying effective therapeutic agents is crucial in addressing this growing problem. Natural products have demonstrated promising anti-tumor activity. In this study, a plant flavonoid, taxifolin, was screened using Weighted Correlation Network Analysis (WGCNA) in combination with the Connectivity Map (CMAP) platform. Taxifolin was confirmed to inhibit the proliferation, migration, and invasion ability of melanoma A375 and MV-3 cells by promoting apoptosis. Additionally, it suppressed the Epithelial-Mesenchymal Transition (EMT) process of melanoma cells. Cyber pharmacological analysis revealed that taxifolin exerts its inhibitory effect on melanoma through the PI3K/AKT signaling pathway, specifically by downregulating the protein expression of p-PI3K and p-AKT. Notably, the addition of SC-79, an activator of the PI3K/AKT signaling pathway, reversed the effects of taxifolin on cell migration and apoptosis. Furthermore, in vivo experiments demonstrated that taxifolin treatment slowed tumor growth in mice without significant toxic effects. Based on these findings, taxifolin holds promise as a potential drug for melanoma treatment.

Unveiling the Dynamic Interplay between Cancer Stem Cells and the Tumor Microenvironment in Melanoma: Implications for Novel Therapeutic Strategies

Cutaneous melanoma still represents a significant health burden worldwide, being responsible for the majority of skin cancer deaths. Key advances in therapeutic strategies have significantly improved patient outcomes; however, most patients experience drug resistance and tumor relapse. Cancer stem cells (CSCs) are a small subpopulation of cells in different tumors, including melanoma, endowed with distinctive capacities of self-renewal and differentiation into bulk tumor cells. Melanoma CSCs are characterized by the expression of specific biomarkers and intracellular pathways; moreover, they play a pivotal role in tumor onset, progression and drug resistance. In recent years, great efforts have been made to dissect the molecular mechanisms underlying the protumor activities of melanoma CSCs to provide the basis for novel CSC-targeted therapies. Herein, we highlight the intricate crosstalk between melanoma CSCs and bystander cells in the tumor microenvironment (TME), including immune cells, endothelial cells and cancer-associated fibroblasts (CAFs), and its role in melanoma progression. Specifically, we discuss the peculiar capacities of melanoma CSCs to escape the host immune surveillance, to recruit immunosuppressive cells and to educate immune cells toward an immunosuppressive and protumor phenotype. We also address currently investigated CSC-targeted strategies that could pave the way for new promising therapeutic approaches for melanoma care.

Mechanisms of Melanoma Progression and Treatment Resistance: Role of Cancer Stem-like Cells

Melanoma is the third most common type of skin cancer, characterized by its heterogeneity and propensity to metastasize to distant organs. Melanoma is a heterogeneous tumor, composed of genetically divergent subpopulations, including a small fraction of melanoma-initiating cancer stem-like cells (CSCs) and many non-cancer stem cells (non-CSCs). CSCs are characterized by their unique surface proteins associated with aberrant signaling pathways with a causal or consequential relationship with tumor progression, drug resistance, and recurrence. Melanomas also harbor significant alterations in functional genes (BRAF, CDKN2A, NRAS, TP53, and NF1). Of these, the most common are the BRAF and NRAS oncogenes, with 50% of melanomas demonstrating the BRAF mutation (BRAFV600E). While the successful targeting of BRAFV600E does improve overall survival, the long-term efficacy of available therapeutic options is limited due to adverse side effects and reduced clinical efficacy. Additionally, drug resistance develops rapidly via mechanisms involving fast feedback re-activation of MAPK signaling pathways. This article updates information relevant to the mechanisms of melanoma progression and resistance and particularly the mechanistic role of CSCs in melanoma progression, drug resistance, and recurrence.