Examples of Inverse Comorbidity between Cancer and Neurodegenerative Diseases: A Possible Role for Noncoding RNA

Unveiling the pathophysiology of restless legs syndrome through transcriptome analysis

The aim of this study was to analyze signaling pathways associated with differentially expressed messenger RNAs in people with restless legs syndrome (RLS). Seventeen RLS patients and 18 controls were enrolled. Coding RNA expression profiling of 12,857 gene transcripts by next-generation sequencing was performed. Enrichment analysis by pathfindR tool was carried-out, with p-adjusted ≤0.001 and fold-change ≥2.5. Nine main different network groups were significantly dysregulated in RLS: infections, inflammation, immunology, neurodegeneration, cancer, neurotransmission and biological, blood and metabolic mechanisms. Genetic predisposition plays a key role in RLS and evidence indicates its inflammatory nature; the high involvement of mainly neurotropic viruses and the TORCH complex might trigger inflammatory/immune reactions in genetically predisposed subjects and activate a series of biological pathways-especially IL-17, receptor potential channels, nuclear factor kappa-light-chain-enhancer of activated B cells, NOD-like receptor, mitogen-activated protein kinase, p53, mitophagy, and ferroptosis-involved in neurotransmitter mechanisms, synaptic plasticity, axon guidance, neurodegeneration, carcinogenesis, and metabolism.

Natural resistance to cancer: A window of hope

As healthcare systems are improving and thereby the life expectancy of human populations is increasing, cancer is representing itself as the second leading cause of death. Although cancer biologists have put enormous effort on cancer research so far, we still have a long way to go before being able to treat cancers efficiently. One interesting approach in cancer biology is to learn from natural resistance and/or predisposition to cancer. Cancer-resistant species and tissues are thought-provoking models whose study shed light on the inherent cancer resistance mechanisms that arose during the course of evolution. On the other hand, there are some syndromes and factors that increase the risk of cancer development, and revealing their underlying mechanisms will increase our knowledge about the process of cancer formation. Here, we review natural resistance and predisposition to cancer and the known mechanisms at play. Further insights from these natural phenomena will help design future cancer research and could ultimately lead to the development of novel cancer therapeutic strategies.

Gene Expression Profiling of Post Mortem Midbrain of Parkinson's Disease Patients and Healthy Controls

Parkinson's disease (PD) stands as the most prevalent degenerative movement disorder, marked by the degeneration of dopaminergic neurons in the substantia nigra of the midbrain. In this study, we conducted a transcriptome analysis utilizing post mortem mRNA extracted from the substantia nigra of both PD patients and healthy control (CTRL) individuals. Specifically, we acquired eight samples from individuals with PD and six samples from CTRL individuals, with no discernible pathology detected in the latter group. RNA sequencing was conducted using the TapeStation 4200 system from Agilent Technologies. A total of 16,148 transcripts were identified, with 92 mRNAs displaying differential expression between the PD and control groups. Specifically, 33 mRNAs were significantly up-regulated, while 59 mRNAs were down-regulated in PD compared to the controls. The identification of statistically significant signaling pathways, with an adjusted p-value threshold of 0.05, unveiled noteworthy insights. Specifically, the enriched categories included cardiac muscle contraction (involving genes such as ATPase Na+/K+ transporting subunit beta 2 (ATP1B2), solute carrier family 8 member A1 (SLC8A1), and cytochrome c oxidase subunit II (COX2)), GABAergic synapse (involving GABA type A receptor-associated protein-like 1 (GABARAPL1), G protein subunit beta 5 (GNB5), and solute carrier family 38 member 2 (SLC38A2), autophagy (involving GABARAPL1 and tumor protein p53-inducible nuclear protein 2 (TP53INP2)), and Fc gamma receptor (FcγR) mediated phagocytosis (involving amphiphysin (AMPH)). These findings uncover new pathophysiological dimensions underlying PD, implicating genes associated with heart muscle contraction. This knowledge enhances diagnostic accuracy and contributes to the advancement of targeted therapies.

Implications of TDP-43 in non-neuronal systems

TAR DNA-binding protein 43 (TDP-43) is a versatile RNA/DNA-binding protein with multifaceted processes. While TDP-43 has been extensively studied in the context of degenerative diseases, recent evidence has also highlighted its crucial involvement in diverse life processes beyond neurodegeneration. Here, we mainly reviewed the function of TDP-43 in non-neurodegenerative physiological and pathological processes, including spermatogenesis, embryonic development, mammary gland development, tumor formation, and viral infection, highlighting its importance as a key regulatory factor for the maintenance of normal functions throughout life. TDP-43 exhibits diverse and sometimes opposite functionality across different cell types through various mechanisms, and its roles can shift at distinct stages within the same biological system. Consequently, TDP-43 operates in both a context-dependent and a stage-specific manner in response to a variety of internal and external stimuli. Video Abstract.

The impact of aging and oxidative stress in metabolic and nervous system disorders: programmed cell death and molecular signal transduction crosstalk

Life expectancy is increasing throughout the world and coincides with a rise in non-communicable diseases (NCDs), especially for metabolic disease that includes diabetes mellitus (DM) and neurodegenerative disorders. The debilitating effects of metabolic disorders influence the entire body and significantly affect the nervous system impacting greater than one billion people with disability in the peripheral nervous system as well as with cognitive loss, now the seventh leading cause of death worldwide. Metabolic disorders, such as DM, and neurologic disease remain a significant challenge for the treatment and care of individuals since present therapies may limit symptoms but do not halt overall disease progression. These clinical challenges to address the interplay between metabolic and neurodegenerative disorders warrant innovative strategies that can focus upon the underlying mechanisms of aging-related disorders, oxidative stress, cell senescence, and cell death. Programmed cell death pathways that involve autophagy, apoptosis, ferroptosis, and pyroptosis can play a critical role in metabolic and neurodegenerative disorders and oversee processes that include insulin resistance, β-cell function, mitochondrial integrity, reactive oxygen species release, and inflammatory cell activation. The silent mating type information regulation 2 homolog 1 (Saccharomyces cerevisiae) (SIRT1), AMP activated protein kinase (AMPK), and Wnt1 inducible signaling pathway protein 1 (WISP1) are novel targets that can oversee programmed cell death pathways tied to β-nicotinamide adenine dinucleotide (NAD+), nicotinamide, apolipoprotein E (APOE), severe acute respiratory syndrome (SARS-CoV-2) exposure with coronavirus disease 2019 (COVID-19), and trophic factors, such as erythropoietin (EPO). The pathways of programmed cell death, SIRT1, AMPK, and WISP1 offer exciting prospects for maintaining metabolic homeostasis and nervous system function that can be compromised during aging-related disorders and lead to cognitive impairment, but these pathways have dual roles in determining the ultimate fate of cells and organ systems that warrant thoughtful insight into complex autofeedback mechanisms.

Epigenetic regulation in major depression and other stress-related disorders: molecular mechanisms, clinical relevance and therapeutic potential

Major depressive disorder (MDD) is a chronic, generally episodic and debilitating disease that affects an estimated 300 million people worldwide, but its pathogenesis is poorly understood. The heritability estimate of MDD is 30-40%, suggesting that genetics alone do not account for most of the risk of major depression. Another factor known to associate with MDD involves environmental stressors such as childhood adversity and recent life stress. Recent studies have emerged to show that the biological impact of environmental factors in MDD and other stress-related disorders is mediated by a variety of epigenetic modifications. These epigenetic modification alterations contribute to abnormal neuroendocrine responses, neuroplasticity impairment, neurotransmission and neuroglia dysfunction, which are involved in the pathophysiology of MDD. Furthermore, epigenetic marks have been associated with the diagnosis and treatment of MDD. The evaluation of epigenetic modifications holds promise for further understanding of the heterogeneous etiology and complex phenotypes of MDD, and may identify new therapeutic targets. Here, we review preclinical and clinical epigenetic findings, including DNA methylation, histone modification, noncoding RNA, RNA modification, and chromatin remodeling factor in MDD. In addition, we elaborate on the contribution of these epigenetic mechanisms to the pathological trait variability in depression and discuss how such mechanisms can be exploited for therapeutic purposes.

Rethinking the Role of Orexin in the Regulation of REM Sleep and Appetite

Orexin plays a significant role in the modulation of REM sleep, as well as in the regulation of appetite and feeding. This review explores, first, the current evidence on the role of orexin in the modulation of sleep and wakefulness and highlights that orexin should be considered essentially as a neurotransmitter inhibiting REM sleep and, to a much lesser extent, a wake promoting agent. Subsequently, the relationship between orexin, REM sleep, and appetite regulation is examined in detail, shedding light on their interconnected nature in both physiological conditions and diseases (such as narcolepsy, sleep-related eating disorder, idiopathic hypersomnia, and night eating syndrome). Understanding the intricate relationship between orexin, REM sleep, and appetite regulation is vital for unraveling the complex mechanisms underlying sleep-wake patterns and metabolic control. Further research in this field is encouraged in order to pave the way for novel therapeutic approaches to sleep disorders and metabolic conditions associated with orexin dysregulation.

Double Trouble: Association of Malignant Melanoma with Sporadic and Genetic Forms of Parkinson's Disease and Asymptomatic Carriers of Related Genes: A Brief Report

Introduction: Previous epidemiological evidence has established the co-occurrence of malignant melanoma (MM) and Parkinson's disease (PD). Shared molecular mechanisms have been proposed to be implicated in this relationship. The aim of the present study was to assess the prevalence of MM in patients with sporadic and genetic types of PD, as well as in asymptomatic carriers of PD-related genes. Methods: Data regarding past medical history and concomitant disease of 1416 patients with PD (including 20 participants with prodromal disease who phenoconverted to PD), 275 healthy controls (HCs) and 670 asymptomatic carriers of PD-related genes were obtained from the database of the Parkinson's Progression Markers Initiative (PPMI). Focus was placed on information about a medical record of MM. We also retrieved data regarding the genetic status of selected PPMI participants with a positive MM history. Results: In total, 46 patients with PD reported a positive MM history. Concerning the genetic forms of PD, nine of these PD patients (2.47%) carried a Leucine Rich Repeat Kinase 2 (LRRK2) gene mutation (mainly the G2019S), while eight (4.49%) harbored a Glucocerebrosidase (GBA) gene mutation (mainly the N370S). No alpha-synuclein (SNCA) gene mutation was identified in patients with an MM history. The remaining 29 PD patients (3.5%) were genetically undetermined. In total, 18 asymptomatic carriers of PD-related genes had a positive medical history for MM: among them, 10 carried an LRRK2 gene mutation (2.69%) and 10 a GBA gene mutation (3.51%) (2 were dual carriers). MM history was identified for seven HCs (2.5%). Conclusions: We replicated the previously reported association between genetically undetermined PD (GU-PD) and MM. A correlation of LRRK2 mutations with the development of MM could not be verified in either symptomatic PD patients or asymptomatic carriers, implicating distinct pathogenetic mechanisms as compared to GU-PD. Importantly, despite the limited literature evidence on Gaucher disease, this study highlights for the first time the relatively high prevalence of MM among asymptomatic and symptomatic PD GBA mutation carriers, with potential clinical implications.

Cognitive Impairment in Multiple Sclerosis

Almost three million individuals suffer from multiple sclerosis (MS) throughout the world, a demyelinating disease in the nervous system with increased prevalence over the last five decades, and is now being recognized as one significant etiology of cognitive loss and dementia. Presently, disease modifying therapies can limit the rate of relapse and potentially reduce brain volume loss in patients with MS, but unfortunately cannot prevent disease progression or the onset of cognitive disability. Innovative strategies are therefore required to address areas of inflammation, immune cell activation, and cell survival that involve novel pathways of programmed cell death, mammalian forkhead transcription factors (FoxOs), the mechanistic target of rapamycin (mTOR), AMP activated protein kinase (AMPK), the silent mating type information regulation 2 homolog 1 (Saccharomyces cerevisiae) (SIRT1), and associated pathways with the apolipoprotein E (APOE-ε4) gene and severe acute respiratory syndrome coronavirus (SARS-CoV-2). These pathways are intertwined at multiple levels and can involve metabolic oversight with cellular metabolism dependent upon nicotinamide adenine dinucleotide (NAD+). Insight into the mechanisms of these pathways can provide new avenues of discovery for the therapeutic treatment of dementia and loss in cognition that occurs during MS.

Cellular Metabolism: A Fundamental Component of Degeneration in the Nervous System

It is estimated that, at minimum, 500 million individuals suffer from cellular metabolic dysfunction, such as diabetes mellitus (DM), throughout the world. Even more concerning is the knowledge that metabolic disease is intimately tied to neurodegenerative disorders, affecting both the central and peripheral nervous systems as well as leading to dementia, the seventh leading cause of death. New and innovative therapeutic strategies that address cellular metabolism, apoptosis, autophagy, and pyroptosis, the mechanistic target of rapamycin (mTOR), AMP activated protein kinase (AMPK), growth factor signaling with erythropoietin (EPO), and risk factors such as the apolipoprotein E (APOE-ε4) gene and coronavirus disease 2019 (COVID-19) can offer valuable insights for the clinical care and treatment of neurodegenerative disorders impacted by cellular metabolic disease. Critical insight into and modulation of these complex pathways are required since mTOR signaling pathways, such as AMPK activation, can improve memory retention in Alzheimer's disease (AD) and DM, promote healthy aging, facilitate clearance of β-amyloid (Aß) and tau in the brain, and control inflammation, but also may lead to cognitive loss and long-COVID syndrome through mechanisms that can include oxidative stress, mitochondrial dysfunction, cytokine release, and APOE-ε4 if pathways such as autophagy and other mechanisms of programmed cell death are left unchecked.

Targeting Orexin Receptors for the Treatment of Insomnia: From Physiological Mechanisms to Current Clinical Evidence and Recommendations

After a detailed description of orexins and their roles in sleep and other medical disorders, we discuss here the current clinical evidence on the effects of dual (DORAs) or selective (SORAs) orexin receptor antagonists on insomnia with the aim to provide recommendations for their further assessment in a context of personalized and precision medicine. In the last decade, many trials have been conducted with orexin receptor antagonists, which represent an innovative and valid therapeutic option based on the multiple mechanisms of action of orexins on different biological circuits, both centrally and peripherally, and their role in a wide range of medical conditions which are often associated with insomnia. A very interesting aspect of this new category of drugs is that they have limited abuse liability and their discontinuation does not seem associated with significant rebound effects. Further studies on the efficacy of DORAs are required, especially on children and adolescents and in particular conditions, such as menopause. Which DORA is most suitable for each patient, based on comorbidities and/or concomitant treatments, should be the focus of further careful research. On the contrary, studies on SORAs, some of which seem to be appropriate also in insomnia in patients with psychiatric diseases, are still at an early stage and, therefore, do not allow to draw definite conclusions.

Role and Dysregulation of miRNA in Patients with Parkinson's Disease

Parkinson's disease (PD) is a neurodegenerative synucleinopathy that has a not yet fully understood molecular pathomechanism behind it. The role of risk genes regulated by small non-coding RNAs, or microRNAs (miRNAs), has also been highlighted in PD, where they may influence disease progression and comorbidities. In this case-control study, we analyzed miRNAs on peripheral blood mononuclear cells by means of RNA-seq in 30 participants, with the aim of identifying miRNAs differentially expressed in PD compared to age-matched healthy controls. Additionally, we investigated the pathways influenced by differentially expressed miRNAs and assessed whether a specific pathway could potentially be associated with PD susceptibility (enrichment analyses performed using the Ingenuity Pathway Analysis tools). Overall, considering that the upregulation of miRNAs might be related with the downregulation of their messenger RNA targets, and vice versa, we found several putative targets of dysregulated miRNAs (i.e., upregulated: hsa-miR-1275, hsa-miR-23a-5p, hsa-miR-432-5p, hsa-miR-4433b-3p, and hsa-miR-4443; downregulated: hsa-miR-142-5p, hsa-miR-143-3p, hsa-miR-374a-3p, hsa-miR-542-3p, and hsa-miR-99a-5p). An inverse connection between cancer and neurodegeneration, called "inverse comorbidity", has also been noted, showing that some genes or miRNAs may be expressed oppositely in neurodegenerative disorders and in some cancers. Therefore, it may be reasonable to consider these miRNAs as potential diagnostic markers and outcome measures.