Knocking out alpha-synuclein in melanoma cells downregulates L1CAM and decreases motility

Alpha-synuclein regulates nucleolar DNA double-strand break repair in melanoma

Although an increased risk of the skin cancer melanoma in people with Parkinson's disease (PD) has been shown in multiple studies, the mechanisms involved are poorly understood, but increased expression of the PD-associated protein alpha-synuclein (αSyn) in melanoma cells may be important. Our previous work suggests that αSyn can facilitate DNA double-strand break (DSB) repair, promoting genomic stability. We now show that αSyn is preferentially enriched within the nucleolus in melanoma, where it colocalizes with DNA damage markers and DSBs. Inducing DSBs specifically within nucleolar ribosomal DNA (rDNA) increases αSyn levels near sites of damage. αSyn knockout increases DNA damage within the nucleolus at baseline, after specific rDNA DSB induction, and prolongs the rate of recovery from this induced damage. αSyn is important downstream of ataxia-telangiectasia-mutated signaling to facilitate MDC1-mediated 53BP1 recruitment to DSBs, reducing micronuclei formation and promoting cellular proliferation, migration, and invasion.

Concomitant Pathologies and Their Impact on Parkinson Disease: A Narrative Overview of Current Evidence

Many clinico-pathological studies point to the presence of multiple comorbidities/co-pathologies in the course of Parkinson disease (PD). Lewy body pathology, the morphological hallmark of PD, rarely exists in isolation, but is usually associated with other concomitant pathologies, in particular Alzheimer disease-related changes (ADNC), cerebrovascular pathologies (macro- and microinfarcts, cerebral small vessel disease, cerebral amyloid angiopathy), TDP-43 pathology as well as multiple pathological combinations. These include cardiovascular disorders, metabolic syndrome, diabetes mellitus, autoimmune and rheumatic diseases, myasthenia gravis, Sjögren's syndrome, restless leg syndrome or other rare disorders, like Fabry disease. A combination of PD and multiple sclerosis (MS) may be due to the immune function of LRRK2 and its interrelation with α-synuclein. COVID-19 and HIV posed considerable impacts on patients with PD. Epidemiological evidence points to a decreased risk for the majority of neoplasms, except melanoma and other skin cancers, while some tumors (breast, brain) are increased. On the other hand, a lower frequency of malignancies preceding early PD markers may argue for their protective effect on PD risk. Possible pathogenetic factors for the association between PD and cancer are discussed. The tremendous heterogeneity of concomitant pathologies and comorbidities observed across the PD spectrum is most likely caused by the complex interplay between genetic, pathogenic and other risk factors, and further research should provide increasing insight into their relationship with idiopathic PD (and other parkinsonian disorders) in order to find better diagnostic tools and probable disease-modifying therapies.

Alpha-synuclein knockout impairs melanoma development and alters DNA damage repair in the TG3 mouse model in a sex-dependent manner

Introduction

Strong evidence suggests links between Parkinson's Disease (PD) and melanoma, as studies have found that people with PD are at an increased risk of developing melanoma and those with melanoma are at increased risk of developing PD. Although these clinical associations are well-established, the cellular and molecular pathways linking these diseases are poorly understood. Recent studies have found a previously unrecognized role for the neurodegeneration-associated protein alpha-synuclein (αSyn) in melanoma; the overexpression of αSyn promotes melanoma cell proliferation and metastasis. However, to our knowledge, no studies have investigated the role of αSyn in in vivo melanoma models outside of a xenograft paradigm.

Methods

Our study created and characterized Snca knockout in the spontaneously developing melanoma TG3 mouse line, TG3+/+Snca-/-.

Results

We show that αSyn loss-of-function significantly delays melanoma onset and slows tumor growth in vivo in males. Furthermore, decreased tumor volume is correlated with a decreased DNA damage signature and increased apoptotic markers, indicating a role for αSyn in modulating the DNA damage response (DDR) pathway.

Discussion

Overall, our study may suggest that targeting αSyn and its role in modulating the DDR and melanomagenesis could serve as a promising new therapeutic target.

α-synuclein expression in glioblastoma restores tumor suppressor function and rescues temozolomide drug resistance

Several studies have shown that Parkinson's disease causative gene products, including α-synuclein (α-syn), display tight links with the tumor suppressor p53. The purpose of this study is to determine the implication of α-syn in glioblastoma development and elucidate how it elicits a tumor suppressor function. We show that the expression of α-syn, a TP53 transcriptional target and a key molecular player in Parkinson's disease, is detected in 1p/19q-codeleted and isocitrate dehydrogenase (IDH)-mutant oligodendroglioma and in IDH-wild-type glioblastoma, while reduced in glioblastoma biopsies, corroborating the link of α-syn expression with a better prognosis among all glioma patients. Accordingly, protein expression is drastically reduced in oligodendrogliomas and glioblastoma biopsies. This could be accounted for by a reduction of p53 transcriptional activity in these samples. Interestingly, genetic manipulation of p53 in glioblastoma cells and in mouse brain shows that p53 up-regulates α-synuclein, a phenotype fully abolished by the prominent p53 hot spot mutation R175H. Downstream to its p53-linked control, α-syn lowers cyclin D1 protein and mRNA levels and reduces glioblastoma cells proliferation in a cyclin D1-dependent-manner. Further, in temozolomide (TMZ)-resistant U87 cells, α-syn reduces O6-methylguanine-DNA methyltransferase (MGMT) expression and rescues drug sensitivity by a mechanism implying its transcriptional activation by X-box binding protein 1 (XBP1), an effector of the UPR response. Furthermore, α-syn lowers MGMT and cyclin D1 (CCDN1) expressions and reduces tumor development in allografted mice. Overall, our data reveals a new role of α-syn as an oligodendroglioma biomarker and as a glioblastoma tumor suppressor capable of either potentiate TMZ effect or avoid TMZ-associated resistance.

Bioinformatic analysis of ferroptosis related biomarkers and potential therapeutic targets in vitiligo

Vitiligo is a complex autoimmune skin disorder characterized by depigmentation and immune dysregulation. To elucidate the role of ferroptosis-related genes (FRGs) in vitiligo, we conducted a comprehensive analysis of gene expression data from the GSE53146 and GSE65127 datasets obtained from the GEO database. We identified 31 differentially expressed FRGs (DE-FRGs), with 21 genes upregulated and 10 downregulated. Functional enrichment analysis revealed that these DE-FRGs are significantly involved in oxidative stress, immune regulation, and vitiligo-associated signaling pathways. Utilizing machine learning approaches, including LASSO and SVM-RFE, we identified four key marker genes (ALOX5, SNCA, SLC1A4, and IL33) with strong diagnostic potential. Immune landscape analysis demonstrated that these marker genes influence immune cell composition, particularly showing correlations with CD8 + T cells and regulatory T cells. Furthermore, drug-gene interaction analysis proposed potential therapeutic targets, while ceRNA network analysis uncovered intricate regulatory relationships involving miRNAs and lncRNAs. Collectively, our findings provide novel insights into the molecular mechanisms underpinning vitiligo and suggest new avenues for diagnostic and therapeutic development.

Nuclear Alpha-Synuclein in Parkinson's Disease and the Malignant Transformation in Melanoma

Background: Alpha-synuclein (ASyn), a marker of Parkinson's disease (PD) and other neurodegenerative processes, plays pivotal roles in neuronal nuclei and synapses. ASyn and its phosphorylated form at Serine 129 (p-ASyn) are involved in DNA protection and repair, processes altered in aging, neurodegeneration, and cancer. Objective: To analyze the localization of p-ASyn in skin biopsies of PD patients and melanoma. Methods: Biopsies from 26 PD patients, 20 melanoma patients, and 31 control subjects were probed and analyzed with a p-ASyn antibody by immunohistochemistry and immunofluorescence. Nuclear positivity was quantified by image analysis. Results: Peripheral nerve endings from healthy subjects show little p-ASyn immunopositivity but notable axonal presence in PD. Control subjects show immunopositivity to p-ASyn along all epidermic strata and scarce presence in their cytoplasm. In contrast, its nuclear presence in PD is weaker, with a higher cytoplasmic and intercellular presence. Nuclear p-ASyn in melanoma varied from similar to control skin in early stage melanoma to a higher rate of empty nuclei in the intermediate stage and total absence of nuclear p-ASyn in severe cases. Interpretation: These findings support the nuclear localization of p-ASyn in skin cells and show that its presence decreases PD and almost disappears in the malignant transformation of melanocytes, redistributing to the cytoplasm and intercellular spaces. This confirms the association between PD and melanoma, providing crucial insights into the role of p-ASyn in both diseases. Trial Registration: ClinicalTrials.gov identifier: NCT01380899.

Alpha-synuclein knockout impairs melanoma development and alters DNA damage repair in the TG3 mouse model in a sex-dependent manner

Strong evidence suggests links between Parkinson's Disease (PD) and melanoma, as studies have found that people with PD are at an increased risk of developing melanoma and those with melanoma are at increased risk of developing PD. Although these clinical associations are well-established, the cellular and molecular pathways linking these diseases are poorly understood. Recent studies have found a previously unrecognized role for the neurodegeneration-associated protein alpha-synuclein (αSyn) in melanoma; the overexpression of αSyn promotes melanoma cell proliferation and metastasis. However, to our knowledge, no studies have investigated the role of αSyn in in vivo melanoma models outside of a xenograft paradigm. Our study created and characterized Snca knockout in the spontaneously developing melanoma TG3 mouse line, TG3+/+Snca-/-. We show that αSyn loss-of-function significantly delays melanoma onset and slows tumor growth in vivo. Furthermore, decreased tumor volume is correlated with a decreased DNA damage signature and increased apoptotic markers, indicating a role for αSyn in modulating the DNA damage response (DDR) pathway. Overall, our study provides evidence that targeting αSyn and its role in modulating the DDR and melanomagenesis could serve as a promising new therapeutic target.

Possible regulation of the immune modulator tetraspanin CD81 by alpha-synuclein in melanoma

We probed the mechanism by which the Parkinson's disease-associated protein α-synuclein (α-syn)/SNCA promotes the pathogenesis and progression of melanoma. We found that the human melanoma cell line SK-MEL-28 in which SNCA is knocked out (SNCA-KO) has low levels of tetraspanin CD81, which is a cell-surface protein that promotes invasion, migration, and immune suppression. Analyzing data from the Cancer Genome Atlas, we show that SNCA and CD81 mRNA levels are positively correlated in melanoma; melanoma survival is inversely related to the levels of SNCA and CD81; and SNCA/CD81 are inversely related to the expression of key cytokine genes (IL12A, IL12B, IFN, IFNG, PRF1 and GZMB) for immune activation and immune cell-mediated killing of melanoma cells. We propose that high levels of α-syn and CD81 in melanoma and in immune cells drive invasion and migration and in parallel cause an immunosuppressive microenvironment; these contributing factors lead to aggressive melanomas.

Transcriptomic analysis of melanoma cells reveals an association of α-synuclein with regulation of the inflammatory response

The Parkinson's disease protein, alpha-synuclein (α-syn/SNCA), is highly expressed in neurons and melanomas. The goal of this study was to reveal the mechanism(s) of α-syn's involvement in melanoma pathogenesis. To decipher the genes and pathways affected by α-syn, we conducted an RNA sequencing analysis of human SK-MEL-28 cells and several SK-MEL-28 SNCA-KO clones. We identified 1098 significantly up-regulated genes and 660 significantly down-regulated genes. Several of the upregulated genes are related to the immune system, i.e., the inflammatory response and the matrisome. We validated five upregulated genes (IL-1β, SAA1, IGFBP5, CXCL8, and CXCL10) by RT-qPCR and detected IGFBP5 and IL-1β in spent media of control and SNCA-KO cells. The levels of each of these secreted proteins were significantly higher in the spent media of the SNCA-KO clones than control cells. These secreted proteins quite likely activate the immune response against SNCA-KO cells. We suggest that, conversely, high levels of α-syn expression in melanoma cells helps the cells evade the immune system by inhibiting the secretion of these immune activating factors.

Association between Parkinson's Disease and Cancer: New Findings and Possible Mediators

Epidemiological evidence points to an inverse association between Parkinson's disease (PD) and almost all cancers except melanoma, for which this association is positive. The results of multiple studies have demonstrated that patients with PD are at reduced risk for the majority of neoplasms. Several potential biological explanations exist for the inverse relationship between cancer and PD. Recent results identified several PD-associated proteins and factors mediating cancer development and cancer-associated factors affecting PD. Accumulating data point to the role of genetic traits, members of the synuclein family, neurotrophic factors, the ubiquitin-proteasome system, circulating melatonin, and transcription factors as mediators. Here, we present recent data about shared pathogenetic factors and mediators that might be involved in the association between these two diseases. We discuss how these factors, individually or in combination, may be involved in pathology, serve as links between PD and cancer, and affect the prevalence of these disorders. Identification of these factors and investigation of their mechanisms of action would lead to the discovery of new targets for the treatment of both diseases.

Alpha-synuclein regulates nucleolar DNA double-strand break repair in melanoma

Although an increased risk of the skin cancer melanoma in people with Parkinson's Disease (PD) has been shown in multiple studies, the mechanisms involved are poorly understood, but increased expression of the PD-associated protein alpha-synuclein (αSyn) in melanoma cells may be important. Our previous work suggests that αSyn can facilitate DNA double-strand break (DSB) repair, promoting genomic stability. We now show that αSyn is preferentially enriched within the nucleolus in the SK-MEL28 melanoma cell line, where it colocalizes with DNA damage markers and DSBs. Inducing DSBs specifically within nucleolar ribosomal DNA (rDNA) increases αSyn levels near sites of damage. αSyn knockout increases DNA damage within the nucleolus at baseline, after specific rDNA DSB induction, and prolongs the rate of recovery from this induced damage. αSyn is important downstream of ATM signaling to facilitate 53BP1 recruitment to DSBs, reducing micronuclei formation and promoting cellular proliferation, migration, and invasion.