Search Results (16)

Lin28b and let-7 miRNA regulate mammalian pubertal initiation and Gonadotropin-releasing hormone (GnRH) production. However, it remains unclear which signaling pathways Lin28b regulates to modulate GnRH production. In this study, the mRNA expression levels of Lin28b and let-7 in the pubertal and juvenile goat hypothalamus and pituitary gland were detected, and Lin28b expression in the pubertal hypothalamus decreased significantly compared with that in juvenile tissues. It was predicted that Lin28b might inhibit GnRH1 expression, which was verified in the GnRH-producing cell model GT1-7 cells. Lin28b inhibited GnRH1 expression and promoted Kiss1/Gpr54 signaling. The pyruvate content and the expression of Hif1a and Hk2, which were related to glycolysis, were also promoted by Lin28b overexpression. Additionally, 77 differentially expressed miRNAs (DEMIs) in Lin28b-overexpressed GT1-7 cells were identified. Bioinformatics analysis and mRNA expression of the target genes of DEMIs revealed that the MAPK and PI3K-AKT-mTOR signaling pathways were key pathways that involved the regulatory effect of Lin28b on GnRH. In GT1-7 cells, GnRH1 expression was suppressed by blocking mTOR signaling with rapamycin, which was rescued by Lin28b overexpression. These results indicate that Lin28b-let-7 regulates GnRH1 expression through several pathways, including the Kiss1/Gpr54, MAPK, and mTOR signaling pathways, which are all related to glucose metabolism and provide new insights into the molecular mechanism of the regulatory role of Lin28b on GnRH production. Full article

Oral cancer, particularly oral squamous cell carcinoma (OSCC), is a significant global health challenge because of its high incidence and limited treatment options. Major risk factors, including tobacco use, alcohol consumption, and specific microbiota, contribute to the disease’s prevalence. Recently, a compelling association between diabetes mellitus (DM) and oral cancer has been identified, with metformin, a widely used antidiabetic drug, emerging as a potential therapeutic agent across various cancers, including OSCC. This review explores both preclinical and clinical studies to understand the mechanisms by which metformin may exert its anticancer effects, such as inhibiting cancer cell proliferation, inducing apoptosis, and enhancing the efficacy of existing treatments. Preclinical studies demonstrate that metformin modulates crucial metabolic pathways, reduces inflammation, and impacts cellular proliferation, thereby potentially lowering cancer risk and improving patient outcomes. Additionally, metformin’s ability to reverse epithelial-to-mesenchymal transition (EMT), regulate the LIN28/let-7 axis, and its therapeutic role in head and neck squamous cell carcinoma (HNSCC) are examined through experimental models. In clinical contexts, metformin shows promise in enhancing therapeutic outcomes and reducing recurrence rates, although challenges such as drug interactions, complex dosing regimens, and risks such as vitamin B12 deficiency remain. Future research should focus on optimizing metformin’s application, investigating its synergistic effects with other therapies, and conducting rigorous clinical trials to validate its efficacy in OSCC treatment. This dual exploration underscores metformin’s potential to play a transformative role in both diabetes management and cancer care, potentially revolutionizing oral cancer treatment strategies. Full article

Muscular atrophy is a complex catabolic condition that develops due to several inflammatory-related disorders, resulting in muscle loss. Tumor necrosis factor alpha (TNF-α) is believed to be one of the leading factors that drive inflammatory response and its progression. Until now, the link between inflammation and muscle wasting has been thoroughly investigated, and the non-coding RNA machinery is a potential connection between the candidates. This study aimed to identify specific miRNAs for muscular atrophy induced by TNF-α in the C2C12 murine myotube model. The difference in expression of fourteen known miRNAs and two newly identified miRNAs was recorded by next-generation sequencing between normal muscle cells and treated myotubes. After validation, we confirmed the difference in the expression of one novel murine miRNA (nov-mmu-miRNA-1) under different TNF-α-inducing conditions. Functional bioinformatic analyses of nov-mmu-miRNA-1 revealed the potential association with inflammation and muscle atrophy. Our results suggest that nov-mmu-miRNA-1 may trigger inflammation and muscle wasting by the downregulation of LIN28A/B, an anti-inflammatory factor in the let-7 family. Therefore, TNF-α is involved in muscle atrophy through the modulation of the miRNA cellular machinery. Here, we describe for the first time and propose a mechanism for the newly discovered miRNA, nov-mmu-miRNA-1, which may regulate inflammation and promote muscle atrophy. Full article

Neuroblastoma (NB) is the most commonly diagnosed extracranial solid tumor in children, accounting for 15% of all childhood cancer deaths. Although the 5-year survival rate of patients with a high-risk disease has increased in recent decades, NB remains a challenge in pediatric oncology, and the identification of novel potential therapeutic targets and agents is an urgent clinical need. The RNA-binding protein LIN28B has been identified as an oncogene in NB and is associated with a poor prognosis. Given that LIN28B acts by negatively regulating the biogenesis of the tumor suppressor let-7 miRNAs, we reasoned that selective interference with the LIN28B/let-7 miRNA interaction would increase let-7 miRNA levels, ultimately leading to reduced NB aggressiveness. Here, we selected (−)-epigallocatechin 3-gallate (EGCG) out of 4959 molecules screened as the molecule with the best inhibitory activity on LIN28B/let-7 miRNA interaction and showed that treatment with PLC/PLGA-PEG nanoparticles containing EGCG (EGCG-NPs) led to an increase in mature let-7 miRNAs and a consequent inhibition of NB cell growth. In addition, EGCG-NP pretreatment reduced the tumorigenic potential of NB cells in vivo. These experiments suggest that the LIN28B/let-7 miRNA axis is a good therapeutic target in NB and that EGCG, which can interfere with this interaction, deserves further preclinical evaluation. Full article

Diffuse midline glioma (DMG) is the most lethal of all childhood cancers. DMGs are driven by histone-tail-mutation-mediated epigenetic dysregulation and partner mutations in genes controlling proliferation and migration. One result of this epigenetic and genetic landscape is the overexpression of LIN28B RNA binding protein. In other systems, LIN28B has been shown to prevent let-7 microRNA biogenesis; however, let-7, when available, faithfully suppresses tumorigenic pathways and induces cellular maturation by preventing the translation of numerous oncogenes. Here, we review the current literature on LIN28A/B and the let-7 family and describe their role in gliomagenesis. Future research is then recommended, with a focus on the mechanisms of LIN28B overexpression and localization in DMG. Full article

People living with HIV (PLHIV) are at a higher risk of having cerebrocardiovascular diseases (CVD) compared to HIV negative (HIV^neg) individuals. The mechanisms underlying this elevated risk remains elusive. We hypothesize that HIV infection results in modified microRNA (miR) content in plasma extracellular vesicles (EVs), which modulates the functionality of vascular repairing cells, i.e., endothelial colony-forming cells (ECFCs) in humans or lineage negative bone marrow cells (lin⁻ BMCs) in mice, and vascular wall cells. PLHIV (N = 74) have increased atherosclerosis and fewer ECFCs than HIV^neg individuals (N = 23). Plasma from PLHIV was fractionated into EVs (HIV^posEVs) and plasma depleted of EVs (HIV PL^depEVs). HIV^posEVs, but not HIV PL^depEVs or HIV^negEVs (EVs from HIV^neg individuals), increased atherosclerosis in apoE^−/− mice, which was accompanied by elevated senescence and impaired functionality of arterial cells and lin⁻ BMCs. Small RNA-seq identified EV-miRs overrepresented in HIV^posEVs, including let-7b-5p. MSC (mesenchymal stromal cell)-derived tailored EVs (TEVs) loaded with the antagomir for let-7b-5p (miRZip-let-7b) counteracted, while TEVs loaded with let-7b-5p recapitulated the effects of HIV^posEVs in vivo. Lin⁻ BMCs overexpressing Hmga2 (a let-7b-5p target gene) lacking the 3′UTR and as such is resistant to miR-mediated regulation showed protection against HIV^posEVs-induced changes in lin⁻ BMCs in vitro. Our data provide a mechanism to explain, at least in part, the increased CVD risk seen in PLHIV. Full article

COVID-19 has presented itself as a challenging task to medical teams and researchers throughout the world, since the outbreak of SARS-CoV-2 started in the Chinese city of Wuhan. To this day, there are still new variants emerging, and the knowledge about the mechanisms used by the virus to infect cells and perpetuate itself are still not well understood. The scientific community is still trying to catch up with the velocity of new variants and, consequently, the new physiological pathways that appear along with it. It is known that the new coronavirus plays a role in changing many molecular pathways to take control of the infected cells. Many of these pathways are related to control genomic expression of certain genes by epigenetic ways, allowing the virus to modulate immune responses and cytokines production. The let-7 family of microRNAs, for instance, are known to promote increased viral fusion in the target cell through a mechanism involving the transmembrane serine protease 2 (TMPRSS2). It was also demonstrated they are able to increase the inflammatory activity through the NF-κB/IL-6/let-7/LIN-28 axis. In addition, let-7 overexpression led to a reduction in inflammatory cytokines and chemokines expression (IL-6, IL-8 and TNF-α). Interestingly, the cytokines modulated by the let-7 family are related to COVID-19-induced cytokine storm observed in patients undergoing clinical phase three. Thus, let-7 can be considered a novel and attractive biomarker for therapeutic purpose. Based on that, the present study aims to critically analyze the immunopathological mechanisms of the microRNA let-7 in the infection caused by SARS-CoV-2. Full article

Lin28 is a pluripotency factor that regulates cancer cell stem-like phenotypes to promote cancer development and therapy-resistant tumor progression. It acts through its cold shock domain and zinc knuckle domain (ZKD) to interact with the Let-7 pre-microRNA and block Let-7 biosynthesis. Chemical inhibition of Lin28 from interacting with Let-7 presents a therapeutic strategy for cancer therapy. Herein, we present the computer-aided development of small molecules by in silico screening 18 million compounds from the ZINC20 library, followed by the biological validation of 163 predicted compounds to confirm 15 new Lin28 inhibitors. We report three lead compounds, Ln7, Ln15, and Ln115, that target the ZKD of both Lin28A and Lin28B isoforms and block Lin28 from binding Let-7. They restore Let-7 expression and suppress tumor oncogenes such as SOX2 in cancer cells and show strong inhibitory effects on cancer cell stem-like phenotypes. However, minimal impacts of these compounds were observed on Lin28-negative cells, confirming the on-target effects of these compounds. We conclude from this study the discovery of several new Lin28 inhibitors as promising candidate compounds that warrant further drug development into potential anticancer therapies. Full article

The proper conceptus elongation in ruminants is critical for the successful placentation and establishment of pregnancy. We have previously shown that the trophectoderm-specific knockdown of LIN28A/B in day 9 ovine blastocysts resulted in increased let-7 miRNAs and reduced conceptus elongation at day 16 of gestation. In this current study, by transcriptome analysis of LIN28A knockdown (AKD) or LIN28B knockdown (BKD) trophectoderm (TE), we explored the downstream target genes of the LIN28-let-7 axis and their roles in the placental and fetal development. We identified 449 differentially expressed genes (DEGs) in AKD TE and 1214 DEGs in BKD TE compared to non-targeting control (NTC). Our analysis further revealed that 210 downregulated genes in AKD TE and 562 downregulated genes in BKD TE were the potential targets of let-7 miRNAs. Moreover, 16 downregulated genes in AKD TE and 57 downregulated and 7 upregulated genes in BKD TE were transcription factors. The DEGs in AKD and BKD TE showed enrichment in the biological processes and pathways critical for placental development and function, and fetal development and growth. The results of this study suggest the potential roles of the LIN28-let-7 axis in placental and fetal development beyond its involvement in trophoblast proliferation and conceptus elongation. Full article

Neuroblastoma (NB) is a tumor of the peripheral sympathetic nervous system that substantially contributes to childhood cancer mortality. NB originates from neural crest cells (NCCs) undergoing a defective sympathetic neuronal differentiation and although the starting events leading to the development of NB remain to be fully elucidated, the master role of genetic alterations in key oncogenes has been ascertained: (1) amplification and/or over-expression of MYCN, which is strongly associated with tumor progression and invasion; (2) activating mutations, amplification and/or over-expression of ALK, which is involved in tumor initiation, angiogenesis and invasion; (3) amplification and/or over-expression of LIN28B, promoting proliferation and suppression of neuroblast differentiation; (4) mutations and/or over-expression of PHOX2B, which is involved in the regulation of NB differentiation, stemness maintenance, migration and metastasis. Moreover, altered microRNA (miRNA) expression takes part in generating pathogenetic networks, in which the regulatory loops among transcription factors, miRNAs and target genes lead to complex and aberrant oncogene expression that underlies the development of a tumor. In this review, we have focused on the circuitry linking the oncogenic transcription factors MYCN and PHOX2B with their transcriptional targets ALK and LIN28B and the tumor suppressor microRNAs let-7, miR-34 and miR-204, which should act as down-regulators of their expression. We have also looked at the physiologic role of these genetic and epigenetic determinants in NC development, as well as in terminal differentiation, with their pathogenic dysregulation leading to NB oncogenesis. Full article

Lin28A and Lin28B are two homologues of the same family of RNA binding proteins (RBPs). The function and molecular mechanism of Lin28A in the formation of primordial germ cells (PGCs) are very clear, but the related research on Lin28B is rarely reported. Here, we found that the overexpression of Lin28B can promote the formation of PGC in vivo. Furthermore, the overexpression of Lin28B also resulted in the inhibition of totipotency gene expression and upregulated the PGCs marker genes, and a significant increase in the number of PGCs in genital ridge, as detected by Periodic Acid-Schiff(PAS) staining. However, the inhibited Lin28B expression showed completely opposite results, which were confirmed on the PGC induction model in vitro. Mechanistically, we found that the overexpression of Lin28B can inhibit the maturation of let-7a-3p, and the results of high-throughput sequencing indicated that let-7a-3p was a negative regulator of the formation process of PGCs. Therefore, we conclude that our results determine that Lin28B participates in the formation of PGCs through let-7a-3p, which set a theoretical foundation for improving the function and mechanism of Lin28 family in the formation of PGCs. Full article

Metastasis remains an unsolved clinical challenge. Two crucial features of metastasizing cancer cells are (a) their ability to dynamically move along the epithelial–hybrid–mesenchymal spectrum and (b) their tumor initiation potential or stemness. With increasing functional characterization of hybrid epithelial/mesenchymal (E/M) phenotypes along the spectrum, recent in vitro and in vivo studies have suggested an increasing association of hybrid E/M phenotypes with stemness. However, the mechanistic underpinnings enabling this association remain unclear. Here, we develop a mechanism-based mathematical modeling framework that interrogates the emergent nonlinear dynamics of the coupled network modules regulating E/M plasticity (miR-200/ZEB) and stemness (LIN28/let-7). Simulating the dynamics of this coupled network across a large ensemble of parameter sets, we observe that hybrid E/M phenotype(s) are more likely to acquire stemness relative to “pure” epithelial or mesenchymal states. We also integrate multiple “phenotypic stability factors” (PSFs) that have been shown to stabilize hybrid E/M phenotypes both in silico and in vitro—such as OVOL1/2, GRHL2, and NRF2—with this network, and demonstrate that the enrichment of hybrid E/M phenotype(s) with stemness is largely conserved in the presence of these PSFs. Thus, our results offer mechanistic insights into recent experimental observations of hybrid E/M phenotype(s) that are essential for tumor initiation and highlight how this feature is embedded in the underlying topology of interconnected EMT (Epithelial-Mesenchymal Transition) and stemness networks. Full article

An appreciation for the complex interactions between the NF-κB transcription factor and the Lin28 RNA binding protein/let-7 microRNA pathways has grown substantially over the past decade. Both the NF-κB and Lin28/let-7 pathways are master regulators impacting cell survival, growth and proliferation, and an understanding of how interfaces between these pathways participate in governing pluripotency, progenitor differentiation, and neuroplastic responses remains an emerging area of research. In this review, we provide a concise summary of the respective pathways and focus on the function of signaling interactions at both the transcriptional and post-transcriptional levels. Regulatory loops capable of providing both reinforcing and extinguishing feedback have been described. We highlight convergent findings in disparate biological systems and indicate future directions for investigation. Full article

MicroRNAs (miRNA), and more recently long non-coding RNAs (lncRNA), are emerging as a driving force for hepatocellular carcinoma (HCC), one of the leading causes of cancer-related death. In this work, we investigated a possible RNA regulatory network involving two oncosuppressive miRNAs, miR-125a and let-7e, and a long non-coding antisense RNA, SPACA6P-AS (SP-AS), all transcribed from the same locus, with SP-AS in the opposite direction and thus carrying complementary sequences to the miRNAs. In vitro experiments validated the binding of the miRNAs to SP-AS. Then, the boosting of either the miRNAs or SP-AS levels demonstrated their reciprocal inhibition. In addition, overexpression of SP-AS resulted in a reduced silencing activity of miR-125a and let-7e toward their key oncogenic targets, i.e., Lin28b, MMP11, SIRT7, Zbtb7a, Cyclin D1, CDC25B, HMGA2, that resulted significantly upregulated. Finally, the analysis of 374 HCC samples in comparison to 50 normal liver tissues showed an upregulation of SP-AS and a reverse expression of miR-125a, not observed for let-7e; consistently, miR-125a oncogenic targets were upregulated. Overall, the data depict a novel competing endogenous RNA (ceRNA) network, ceRNET, whereby miR-125a can regulate the expression of SP-AS, which in turn regulates the miRNA by competing with the binding to the mRNA targets. We speculate that the unbalancing of any network component may contribute to hepatocarcinogenesis. Full article

Placental disorders are a major cause of pregnancy loss in humans, and 40–60% of embryos are lost between fertilization and birth. Successful embryo implantation and placental development requires rapid proliferation, invasion, and migration of trophoblast cells. In recent years, microRNAs (miRNAs) have emerged as key regulators of molecular pathways involved in trophoblast function. A miRNA binds its target mRNA in the 3ʹ-untranslated region (3ʹ-UTR), causing its degradation or translational repression. Lethal-7 (let-7) miRNAs induce cell differentiation and reduce cell proliferation by targeting proliferation-associated genes. The oncoprotein LIN28 represses the biogenesis of mature let-7 miRNAs. Proliferating cells have high LIN28 and low let-7 miRNAs, whereas differentiating cells have low LIN28 and high let-7 miRNAs. In placenta, low LIN28 and high let-7 miRNAs can lead to reduced proliferation of trophoblast cells, resulting in abnormal placental development. In trophoblast cells, let-7 miRNAs reduce the expression of proliferation factors either directly by binding their mRNA in 3ʹ-UTR or indirectly by targeting the AT-rich interaction domain (ARID)3B complex, a transcription-activating complex comprised of ARID3A, ARID3B, and histone demethylase 4C (KDM4C). In this review, we discuss regulation of trophoblast function by miRNAs, focusing on the role of LIN28-let-7-ARID3B pathway in placental development. Full article