Metformin Treatment Modulates Long Non-Coding RNA Isoforms Expression in Human Cells

Unveiling overlooked pathways: The uric acid catabolism genes in the human genome

In hominids, including Homo sapiens, uric acid is the end product of purine catabolism. In contrast, other placental mammals further degrade uric acid to (S)-allantoin by enzymes such as urate oxidase (uricase), HIU hydrolase (HIUase), and OHCU decarboxylase. Some organisms, such as frogs and fish, hydrolyze (S)-allantoin to allantoate and eventually to (S)-ureidoglycolate and urea, while marine invertebrates convert urea to ammonium. In H. sapiens, mutations in the uricase gene led to a reduction in the selective pressure for maintaining the integrity of the genes encoding the other enzymes of the purine catabolism pathway, resulting in an accumulation of uric acid. The hyperuricemia resulting from this accumulation is associated with gout, cardiovascular disease, diabetes, and preeclampsia. Many commonly used drugs, such as aspirin, can also increase uric acid levels. Despite the apparent absence of these enzymes in H. sapiens, there appears to be production of transcripts for uricase (UOX), HIUase (URAHP), OHCU decarboxylase (URAD), and allantoicase (ALLC). While some URAHP transcripts are classified as long non-coding RNAs (lncRNAs), URAD and ALLC produce protein-coding transcripts. Given the presence of these transcripts in various tissues, we hypothesized that they may play a role in the regulation of purine catabolism and the pathogenesis of diseases associated with hyperuricemia. Here, we specifically investigate the unique aspects of purine catabolism in H. sapiens, the effects mutations of the uricase gene, and the potential regulatory role of the corresponding transcripts. These findings open new avenues for research and therapeutic approaches for the treatment of hyperuricemia and related diseases.

Non-coding RNAs as potential targets in metformin therapy for cancer

Metformin, a widely used oral hypoglycemic drug, has emerged as a potential therapeutic agent for cancer treatment. While initially known for its role in managing diabetes, accumulating evidence suggests that metformin exhibits anticancer properties through various mechanisms. Several cellular or animal experiments have attempted to elucidate the role of non-coding RNA molecules, including microRNAs and long non-coding RNAs, in mediating the anticancer effects of metformin. The present review summarized the current understanding of the mechanisms by which non-coding RNAs modulate the response to metformin in cancer cells. The regulatory roles of non-coding RNAs, particularly miRNAs, in key cellular processes such as cell proliferation, cell death, angiogenesis, metabolism and epigenetics, and how metformin affects these processes are discussed. This review also highlights the role of lncRNAs in cancer types such as lung adenocarcinoma, breast cancer, and renal cancer, and points out the need for further exploration of the mechanisms by which metformin regulates lncRNAs. In addition, the present review explores the potential advantages of metformin-based therapies over direct delivery of ncRNAs, and this review highlights the mechanisms of non-coding RNA regulation when metformin is combined with other therapies. Overall, the present review provides insights into the molecular mechanisms underlying the anticancer effects of metformin mediated by non-coding RNAs, offering novel opportunities for the development of personalized treatment strategies in cancer patients.

A protective role of nintedanib in peritoneal fibrosis through H19-EZH2-KLF2 axis via impeding mesothelial-to-mesenchymal transition

BACKGROUND

Peritoneal fibrosis (PF), a common complication of long-term peritoneal dialysis, accounts for peritoneal ultrafiltration failure to develop into increased mortality. Nintedanib has previously been shown to protect against multi-organ fibrosis, including PF. Unfortunately, the precise molecular mechanism underlying nintedanib in the pathogenesis of PF remains elusive.

METHODS

The mouse model of PF was generated by chlorhexidine gluconate (CG) injection with or without nintedanib administration, either with the simulation for the cell model of PF by constructing high-glucose (HG)-treated human peritoneal mesothelial cells (HPMCs). HE and Masson staining were applied to assess the histopathological changes of peritoneum and collagen deposition. FISH, RT-qPCR, western blot and immunofluorescence were employed to examine distribution or expression of targeted genes. Cell viability was detected using CCK-8 assay. Cell morphology was observed under a microscope. RNA immunoprecipitation (RIP) and chromatin immunoprecipitation (ChIP) assays were applied to validate the H19-EZH2-KLF2 regulatory axis.

RESULTS

Aberrantly overexpressed H19 was observed in both the mouse and cell model of PF, of which knockdown significantly blocked HG-induced mesothelial-to-mesenchymal transition (MMT) of HPMCs. Moreover, loss of H19 further strengthened nintedanib-mediated suppressive effects against MMT process in a mouse model of PF. Mechanistically, H19 could epigenetically repressed KLF2 via recruiting EZH2. Furthermore, TGF-β/Smad pathway was inactivated by nintedanib through mediating H19/KLF2 axis.

CONCLUSION

In summary, nintedanib disrupts MMT process through regulating H19/EZH2/KLF2 axis and TGF-β/Smad pathway, which laid the experimental foundation for nintedanib in the treatment of PF.

Role of long non-coding RNAs in the pathophysiology of Alzheimer's disease and other dementias

Dementia is the term used to describe a group of cognitive disorders characterized by a decline in memory, thinking, and reasoning abilities that interfere with daily life activities. Examples of dementia include Alzheimer's Disease (AD), Frontotemporal dementia (FTD), Amyotrophic lateral sclerosis (ALS), Vascular dementia (VaD) and Progressive supranuclear palsy (PSP). AD is the most common form of dementia. The hallmark pathology of AD includes formation of β-amyloid (Aβ) oligomers and tau hyperphosphorylation in the brain, which induces neuroinflammation, oxidative stress, synaptic dysfunction, and neuronal apoptosis. Emerging studies have associated long non-coding RNAs (lncRNAs) with the pathogenesis and progression of the neurodegenerative diseases. LncRNAs are defined as RNAs longer than 200 nucleotides that lack the ability to encode functional proteins. LncRNAs play crucial roles in numerous biological functions for their ability to interact with different molecules, such as proteins and microRNAs, and subsequently regulate the expression of their target genes at transcriptional and post-transcriptional levels. In this narrative review, we report the function and mechanisms of action of lncRNAs found to be deregulated in different types of dementia, with the focus on AD. Finally, we discuss the emerging role of lncRNAs as biomarkers of dementias.

The anti-diabetic effects of metformin are mediated by regulating long non-coding RNA

Type 2 diabetes (T2D) is a metabolic disease with complex etiology and mechanisms. Long non-coding ribonucleic acid (LncRNA) is a novel class of functional long RNA molecules that regulate multiple biological functions through various mechanisms. Studies in the past decade have shown that lncRNAs may play an important role in regulating insulin resistance and the progression of T2D. As a widely used biguanide drug, metformin has been used for glucose lowering effects in clinical practice for more than 60 years. For diabetic therapy, metformin reduces glucose absorption from the intestines, lowers hepatic gluconeogenesis, reduces inflammation, and improves insulin sensitivity. However, despite being widely used as the first-line oral antidiabetic drug, its mechanism of action remains largely elusive. Currently, an increasing number of studies have demonstrated that the anti-diabetic effects of metformin were mediated by the regulation of lncRNAs. Metformin-regulated lncRNAs have been shown to participate in the inhibition of gluconeogenesis, regulation of lipid metabolism, and be anti-inflammatory. Thus, this review focuses on the mechanisms of action of metformin in regulating lncRNAs in diabetes, including pathways altered by metformin via targeting lncRNAs, and the potential targets of metformin through modulation of lncRNAs. Knowledge of the mechanisms of lncRNA modulation by metformin in diabetes will aid the development of new therapeutic drugs for T2D in the future.

Identification and validation of a novel long non-coding RNA (LINC01465) in ovarian cancer

Epithelial Ovarian Cancer (EOC) is a heterogeneous disease usually diagnosed at advanced stages. Therefore, early detection is crucial for better survival. Despite the advances in ovarian research, mechanisms underlying EOC carcinogenesis are not elucidated. We performed chromatin immunoprecipitation sequencing to identify genes regulated by E2F5, a transcription factor involved in ovarian carcinogenesis. Results revealed several putative candidate genes (115 protein-coding genes, 20 lncRNAs, 6 pseudogenes, and 4 miRNAs). A literature review and bioinformatics analysis of these genes revealed a novel lncRNA candidate (LINC01465) in EOC. We validated LINC01465 by quantifying its expression in EOC cell lines and selected OVSAHO and SKOV3 as a model with high LINC01465 levels. We silenced LINC01465 and performed proliferation, wound healing, invasion, and drug resistance assays. Knocking-down LINC01465 resulted in reduced migration, suggesting potential involvement in EOC. Furthermore, to identify the significance of LINC01465 in chemoresistance, we assessed the LINC01465 levels in A2780 S cells treated with malformin, which revealed higher LINC01465 expression as compared to untreated A2780S cells implying the involvement of LINC01465 in cell death. Thus, this study unraveled the repertoire of E2F5 regulated candidate genes and suggested a putative role of LINC01465 in malformin-induced cell death in EOC.