Emerging Role of Non-Coding RNAs in Senescence

H, Elsayed Ahmed R, Muralidharan P, Paulsamy P. SASP Modulation for Cellular Rejuvenation and Tissue Homeostasis: Therapeutic Strategies and Molecular Insights

Cellular senescence regulates aging, tissue maintenance, and disease progression through the Senescence-Associated Secretory Phenotype (SASP), a secretory profile of cytokines, chemokines, growth factors, and matrix-remodeling enzymes. While transient SASP aids wound healing, its chronic activation drives inflammation, fibrosis, and tumorigenesis. This review examines SASP's molecular regulation, dual roles in health and pathology, and therapeutic potential. The following two main strategies are explored: senescence clearance, which eliminates SASP-producing cells, and SASP modulation, which refines secretion to suppress inflammation while maintaining regenerative effects. Key pathways, including NF-κB, C/EBPβ, and cGAS-STING, are discussed alongside pharmacological, immunotherapeutic, gene-editing, and epigenetic interventions. SASP heterogeneity necessitates tissue-specific biomarkers for personalized therapies. Challenges include immune interactions, long-term safety, and ethical considerations. SASP modulation emerges as a promising strategy for aging, oncology, and tissue repair, with future advancements relying on multi-omics and AI-driven insights to optimize clinical outcomes.

Circadian rhythm, hypoxia, and cellular senescence: From molecular mechanisms to targeted strategies

Cellular senescence precipitates a decline in physiological activities and metabolic functions, often accompanied by heightened inflammatory responses, diminished immune function, and impaired tissue and organ performance. Despite extensive research, the mechanisms underpinning cellular senescence remain incompletely elucidated. Emerging evidence implicates circadian rhythm and hypoxia as pivotal factors in cellular senescence. Circadian proteins are central to the molecular mechanism governing circadian rhythm, which regulates homeostasis throughout the body. These proteins mediate responses to hypoxic stress and influence the progression of cellular senescence, with protein Brain and muscle arnt-like 1 (BMAL1 or Arntl) playing a prominent role. Hypoxia-inducible factor-1α (HIF-1α), a key regulator of oxygen homeostasis within the cellular microenvironment, orchestrates the transcription of genes involved in various physiological processes. HIF-1α not only impacts normal circadian rhythm functions but also can induce or inhibit cellular senescence. Notably, HIF-1α may aberrantly interact with BMAL1, forming the HIF-1α-BMAL1 heterodimer, which can instigate multiple physiological dysfunctions. This heterodimer is hypothesized to modulate cellular senescence by affecting the molecular mechanism of circadian rhythm and hypoxia signaling pathways. In this review, we elucidate the intricate relationships among circadian rhythm, hypoxia, and cellular senescence. We synthesize diverse evidence to discuss their underlying mechanisms and identify novel therapeutic targets to address cellular senescence. Additionally, we discuss current challenges and suggest potential directions for future research. This work aims to deepen our understanding of the interplay between circadian rhythm, hypoxia, and cellular senescence, ultimately facilitating the development of therapeutic strategies for aging and related diseases.

The Intersection of Epigenetics and Senolytics in Mechanisms of Aging and Therapeutic Approaches

The biological process of aging is influenced by a complex interplay of genetic, environmental, and epigenetic factors. Recent advancements in the fields of epigenetics and senolytics offer promising avenues for understanding and addressing age-related diseases. Epigenetics refers to heritable changes in gene expression without altering the DNA sequence, with mechanisms like DNA methylation, histone modification, and non-coding RNA regulation playing critical roles in aging. Senolytics, a class of drugs targeting and eliminating senescent cells, address the accumulation of dysfunctional cells that contribute to tissue degradation and chronic inflammation through the senescence-associated secretory phenotype. This scoping review examines the intersection of epigenetic mechanisms and senolytic therapies in aging, focusing on their combined potential for therapeutic interventions. Senescent cells display distinct epigenetic signatures, such as DNA hypermethylation and histone modifications, which can be targeted to enhance senolytic efficacy. Epigenetic reprogramming strategies, such as induced pluripotent stem cells, may further complement senolytics by rejuvenating aged cells. Integrating epigenetic modulation with senolytic therapy offers a dual approach to improving healthspan and mitigating age-related pathologies. This narrative review underscores the need for continued research into the molecular mechanisms underlying these interactions and suggests future directions for therapeutic development, including clinical trials, biomarker discovery, and combination therapies that synergistically target aging processes.

The oncogenic lncRNA MIR503HG suppresses cellular senescence counteracting supraphysiological androgen treatment in prostate cancer

BACKGROUND

The androgen receptor (AR), a ligand-dependent transcription factor, plays a key role in regulating prostate cancer (PCa) growth. The novel bipolar androgen therapy (BAT) uses supraphysiological androgen levels (SAL) that suppresses growth of PCa cells and induces cellular senescence functioning as a tumor suppressive mechanism. The role of long non-coding RNAs (lncRNAs) in the regulation of SAL-mediated senescence remains unclear. This study focuses on the SAL-repressed lncRNA MIR503HG, examining its involvement in androgen-controlled cellular senescence in PCa.

METHODS

Transcriptome and ChIP-Seq analyses of PCa cells treated with SAL were conducted to identify SAL-downregulated lncRNAs. Expression levels of MIR503HG were analyzed in 691 PCa patient tumor samples, mouse xenograft tumors and treated patient-derived xenografts. Knockdown and overexpression experiments were performed to assess the role of MIR503HG in cellular senescence and proliferation using senescence-associated β-Gal assays, qRT-PCRs, and Western blotting. The activity of MIR503HG was confirmed in PCa tumor spheroids.

RESULTS

A large patient cohort analysis shows that MIR503HG is overexpressed in metastatic PCa and is associated with reduced patient survival, indicating its potential oncogenic role. Notably, SAL treatment suppresses MIR503HG expression across four different PCa cell lines and patient-derived xenografts but interestingly not in the senescence-resistant LNCaP Abl EnzaR cells. Functional assays reveal that MIR503HG promotes PCa cell proliferation and inhibits SAL-mediated cellular senescence, partly through miR-424-5p. Mechanistic analyses and rescue experiments indicate that MIR503HG regulates the AKT-p70S6K and the p15INK4b-pRb pathway. Reduced expression of MIR503HG by SAL or knockdown resulted in decreased BRCA2 levels suggesting a role in DNA repair mechanisms and potential implications for PARP inhibitor sensitivity by SAL used in BAT clinical trial.

CONCLUSIONS

The lncRNA MIR503HG acts as an oncogenic regulator in PCa by repressing cellular senescence. SAL-induced suppression of MIR503HG enhances the tumor-suppressive effects of AR signaling, suggesting that MIR503HG could serve as a biomarker for BAT responsiveness and as a target for combination therapies with PARP inhibitors.

Ageing-associated long non-coding RNA extends lifespan and reduces translation in non-dividing cells

Genomes produce widespread long non-coding RNAs (lncRNAs) of largely unknown functions. We characterize aal1 (ageing-associated lncRNA), which is induced in quiescent fission yeast cells. Deletion of aal1 shortens the chronological lifespan of non-dividing cells, while ectopic overexpression prolongs their lifespan, indicating that aal1 acts in trans. Overexpression of aal1 represses ribosomal-protein gene expression and inhibits cell growth, and aal1 genetically interacts with coding genes functioning in protein translation. The aal1 lncRNA localizes to the cytoplasm and associates with ribosomes. Notably, aal1 overexpression decreases the cellular ribosome content and inhibits protein translation. The aal1 lncRNA binds to the rpl1901 mRNA, encoding a ribosomal protein. The rpl1901 levels are reduced ~2-fold by aal1, which is sufficient to extend lifespan. Remarkably, the expression of the aal1 lncRNA in Drosophila boosts fly lifespan. We propose that aal1 reduces the ribosome content by decreasing Rpl1901 levels, thus attenuating the translational capacity and promoting longevity. Although aal1 is not conserved, its effect in flies suggests that animals feature related mechanisms that modulate ageing, based on the conserved translational machinery.

Genetic and Epigenetic Interactions Involved in Senescence of Stem Cells

Cellular senescence is a permanent condition of cell cycle arrest caused by a progressive shortening of telomeres defined as replicative senescence. Stem cells may also undergo an accelerated senescence response known as premature senescence, distinct from telomere shortening, as a response to different stress agents. Various treatment protocols have been developed based on epigenetic changes in cells throughout senescence, using different drugs and antioxidants, senolytic vaccines, or the reprogramming of somatic senescent cells using Yamanaka factors. Even with all the recent advancements, it is still unknown how different epigenetic modifications interact with genetic profiles and how other factors such as microbiota physiological conditions, psychological states, and diet influence the interaction between genetic and epigenetic pathways. The aim of this review is to highlight the new epigenetic modifications that are involved in stem cell senescence. Here, we review recent senescence-related epigenetic alterations such as DNA methylation, chromatin remodeling, histone modification, RNA modification, and non-coding RNA regulation outlining new possible targets for the therapy of aging-related diseases. The advantages and disadvantages of the animal models used in the study of cellular senescence are also briefly presented.

Senescence and fibrosis in salivary gland aging and disease

Salivary gland hypofunction is highly prevalent in aged and diseased individuals leading to significant discomfort and morbidity. One factor that contributes to salivary gland hypofunction is cellular aging, or senescence. Senescent cells can impair gland function by secreting paracrine-acting growth factors and cytokines, known as senescence-associated secretory phenotype (SASP) factors. These SASP factors stimulate inflammation, propagate the senescent phenotype through the bystander effect, and stimulate fibrosis. As senotherapeutics that target senescent cells have shown effectiveness in limiting disease manifestations in other conditions, there is interest in the use of these drugs to treat salivary gland hypofunction. In this review, we highlight the contribution of senescence and fibrosis to salivary gland pathologies. We also discuss therapeutic approaches to eliminate or modulate the senescent SASP phenotype for treating age-related salivary gland diseases and extending health span.

The Impact of Long Noncoding RNAs in Tissue Regeneration and Senescence

Overcoming senescence with tissue engineering has a promising impact on multiple diseases. Here, we provide an overview of recent studies in which cellular senescence was inhibited through the up/downregulation of specific lncRNAs. This approach prevented senescence in the bones, joints, nervous system, heart, and blood vessels, with a potential impact on regeneration and the prevention of osteoarthritis and osteoporosis, as well as neurodegenerative and cardiovascular diseases. Senescence of the skin and liver could also be prevented through the regulation of cellular levels of specific lncRNAs, resulting in the rejuvenation of cells from these organs and their potential protection from disease. From these exciting achievements, which support tissue regeneration and are not restricted to stem cells, we propose lncRNA regulation through RNA or gene therapies as a prospective preventive and therapeutic approach against aging and multiple aging-related diseases.

Naringenin induces the cell apoptosis of acute myeloid leukemia cells by regulating the lncRNA XIST/miR-34a/HDAC1 signaling

Acute myeloid leukemia (AML) is a life-threatening aggressive malignancy of the bone marrow and has posed a great challenge to the clinic, due to a lack of fully understanding of the molecular mechanism. Histone deacetylase 1 (HDAC1) has been reported to be a therapeutic target for treating AML. Naringenin (Nar) may act as an anti-leukemic agent and suppress the expression of HDACs. However, the potential underlying mechanism of Nar in suppressing the activity of HDAC1 remains unclear. Here, we found that Nar induced the apoptosis, decreased the expression of lncRNA XIST and HDAC1, and increased the expression of microRNA-34a in HL60 cells. Sh-XIST transfection could induce cell apoptosis. On the contrary, the forced expression of XIST might reverse the biological actions of Nar. XIST could sponge miR-34a, which targeted to degrade HDAC1. The forced expression of HDAC1 could effectively reverse the effects of Nar. Thus, Nar can induce cell apoptosis by mediating the expression of lncRNA XIST/miR-34a/HDAC1 signaling in HL60 cells.

microRNAs Associated with Carotid Plaque Development and Vulnerability: The Clinician's Perspective

Ischemic stroke (IS) related to atherosclerosis of large arteries is one of the leading causes of mortality and disability in developed countries. Atherosclerotic internal carotid artery stenosis (ICAS) contributes to 20% of all cerebral ischemia cases. Nowadays, atherosclerosis prevention and treatment measures aim at controlling the atherosclerosis risk factors, or at the interventional (surgical or endovascular) management of mature occlusive lesions. There is a definite lack of the established circulating biomarkers which, once modulated, could prevent development of atherosclerosis, and consequently prevent the carotid-artery-related IS. Recent studies emphasize that microRNA (miRNA) are the emerging particles that could potentially play a pivotal role in this approach. There are some research studies on the association between the expression of small non-coding microRNAs with a carotid plaque development and vulnerability. However, the data remain inconsistent. In addition, all major studies on carotid atherosclerotic plaque were conducted on cell culture or animal models; very few were conducted on humans, whereas the accumulating evidence demonstrates that it cannot be automatically extrapolated to processes in humans. Therefore, this paper aims to review the current knowledge on how miRNA participate in the process of carotid plaque formation and rupture, as well as stroke occurrence. We discuss potential target miRNA that could be used as a prognostic or therapeutic tool.