The lncRNA LETS1 promotes TGF-β-induced EMT and cancer cell migration by transcriptionally activating a TβR1-stabilizing mechanism

LncRNAs in oncogenic microenvironment: from threat to therapy

LncRNAs are RNA molecules of more than 200 nucleotides in length and participate in cellular metabolism and cellular responses through their diverse interactomedespite having no protein-coding capabilities. Such significant interactions also implicate the presence of lncRNAs in complex pathobiological pathways of various diseases, affecting cellular survival by modulating autophagy, inflammation and apoptosis. Proliferating cells harbour a complex microenvironment that mainly stimulate growth-specific activities such as DNA replication, repair, and protein synthesis. They also recognise damages at the macromolecular level, preventing them from reaching the next-generation. LncRNAs have shown significant association with the events occurring towards proliferation, regulating key events in dividing cells, and dysregulation of lncRNA transcriptome affects normal cellular life-cycle, promoting the development of cancer. Furthermore, lncRNAs also demonstrated an association with cancer growth and progression by regulating key pathways governing cell growth, epithelial-mesenchymal transition and metastasis. This makes lncRNAs an attractive target for the treatment of cancer and can also be used as a marker for the diagnosis and prognosis of diseases due to their differential expression in diseased samples. This review delves into the correlation of the lncRNA transcriptome with the fundamental cellular signalling and how this crosstalk shapes the complexity of the oncogenic microhabitat.

Long Non-Coding RNAs: Key Regulators of Tumor Epithelial/Mesenchymal Plasticity and Cancer Stemness

Long non-coding RNAs (lncRNAs) are a class of non-coding RNA molecules with transcripts longer than 200 bp, which were initially thought to be noise from genomic transcription without biological function. However, since the discovery of H19 in 1980 and Xist in 1990, increasing evidence has shown that lncRNAs regulate gene expression at epigenetic, transcriptional, and post-transcriptional levels through specific regulatory actions and are involved in the development of cancer and other diseases. Despite many lncRNAs being expressed at lower levels than those of protein-coding genes with less sequence conservation across species, lncRNAs have become an intense area of RNA research. They exert diverse biological functions such as inducing chromatin remodeling, recruiting transcriptional machinery, acting as competitive endogenous RNAs for microRNAs, and modulating protein-protein interactions. Epithelial-mesenchymal transition (EMT) is a developmental process, associated with embryonic development, wound healing, and cancer progression. In the context of oncogenesis, the EMT program is transiently activated and confers migratory/invasive and cancer stem cell (CSC) properties to tumor cells, which are crucial for malignant progression, metastasis, and therapeutic resistance. Accumulating evidence has revealed that lncRNAs play crucial roles in the regulation of tumor epithelial/mesenchymal plasticity (EMP) and cancer stemness. Here, we summarize the emerging roles and molecular mechanisms of lncRNAs in regulating tumor cell EMP and their effects on tumor initiation and progression through regulation of CSCs. We also discuss the potential of lncRNAs as diagnostic and prognostic biomarkers and therapeutic targets.

Unveiling the role of Pafah1b3 in liver fibrosis: A novel mechanism revealed

Liver fibrosis is a common outcome of various chronic hepatic insults, characterized by excessive extracellular matrix (ECM) deposition. The precise mechanisms, however, remain largely undefined. This study identified an elevated expression of platelet-activating factor acetylhydrolase 1B3 (Pafah1b3) in liver tissues from both carbon tetrachloride (CCl4)-treated mice and patients with cirrhosis. Deletion of Pafah1b3 significantly attenuated CCl4-induced fibrosis, hepatic stellate cell (HSC) activation, and activation of transforming growth factor-β (TGF-β) signaling. Mechanistically, PAFAH1B3 binds to mothers against decapentaplegic homolog 7 (SMAD7), disrupting SMAD7's interaction with TGF-β receptor 1 (TβR1), which subsequently decreases TβR1 ubiquitination and degradation. Pharmacological inhibition using 3-IN-P11, a specific Pafah1b3 inhibitor, conferred protective effects against CCl4-induced fibrosis in mice. Furthermore, Pafah1b3 deficiency reduced hepatic inflammation. Overall, these results establish a pivotal role for Pafah1b3 in modulating TGF-β signaling and driving HSC activation.

LncRNA XIST/miR-455-3p/HOXC4 axis promotes breast cancer development by activating TGF-β/SMAD signaling pathway

Breast cancer is the second primary cause of cancer death among women. Long non-coding RNA (lncRNA) X-inactive specific transcript (XIST) is a central regulator for X chromosome inactivation, and its abnormal expression is a primary feature of breast cancer. So far, the mechanism of XIST in breast cancer has not been fully elucidated. We attempted to illustrate the mechanism of XIST in breast cancer. The expressions of XIST, microRNA-455-3p (miR-455-3p) in breast cancer were measured using quantitative real-time PCR. The expressions of homeobox C4 (HOXC4) were assessed with immunohistochemical and Western blot. Also, the functions of XIST in breast cancer were assessed by Cell Counting Kit-8 analysis, colony formation assay, flow cytometry, Western blot, Transwell, and cell scratch assays. Meanwhile, the mechanism of XIST in breast cancer was validated using database analysis and dual-luciferase reporter assay. Furthermore, the function of XIST in breast cancer in vivo was estimated by tumor xenograft model, immunohistochemical assay, and hematoxylin-eosin staining. XIST and HOXC4 expressions were increased, but miR-455-3p expressions were decreased in breast cancer tissues and cells. Knocking down XIST restrained breast cancer cell proliferation, invasion, migration, epithelial-mesenchymal transformation (EMT), and induced cell cycle arrest at G0/G1. Meanwhile, XIST interacted with miR-455-3p, while miR-455-3p interacted with HOXC4. XIST knockdown repressed breast cancer cell proliferation, invasion, and EMT, while miR-455-3p inhibitor or HOXC4 overexpression abolished those impacts. HOXC4 overexpression also blocked the impacts of miR-455-3p mimic on breast cancer cell malignant behavior. In vivo experimental data further indicated that XIST knockdown repressed breast cancer cell tumorigenic ability, and decreased HOXC4 and p-SMAD3 (TGF-β/SMAD-related protein) expressions.XIST/miR-455-3p/HOXC4 facilitated breast cancer development by activating the TGF-β/SMAD pathway.

ATF1 promotes ferroptosis resistance in lung cancer through enhancing mRNA stability of PROM2

BACKGROUND

Ferroptotic proteins are promising therapeutic targets for lung cancer. The PROM2 is upregulated in lung cancer and known to suppress ferroptosis. This study examined the molecular mechanisms for PROM2-induced ferroptosis resistance in lung cancer.

METHODS

Ferroptosis in lung cancer was assessed by iron kit, and transmission electron microscopy was applied to observe the changes in mitochondrial morphology. BODIPY™ was applied to test the lipid ROS, and MeRIP was performed to test the m6A modification of PROM2. RIP assay was employed for confirming the binding between METTL3 and PROM2. In addition, dual luciferase assay was employed for exploring the transcriptional regulation of ATF1 to METTL3, and the binding relation between ATF1 and METTL3 promoter region was explored by ChIP assay.

RESULTS

Expression levels of PROM2 were significantly higher in lung cancer cell lines than a noncancerous control line, and PROM2 knockdown significantly reduced both cancer cell viability and proliferation rate. In addition, PROM2 knockdown reduced xenograft tumor growth and exacerbated erastin-induced ferroptosis. Compared to PROM2 mRNA from control cells, transcripts in lung cancer cells exhibited enhanced m6A levels, and showed greater binding with METTL3. Further, ATF1 upregulated METTL3 transcription, thereby stabilizing PROM2 mRNA and increasing ferroptosis resistance.

CONCLUSION

ATF1 could promote ferroptosis resistance in lung cancer through enhancing mRNA stability of PROM2. Thus, our work might shed novel insights on discovering therapeutic strategy for lung cancer.

RNA regulatory mechanisms controlling TGF-β signaling and EMT in cancer

Epithelial-mesenchymal transition (EMT) is a major contributor to metastatic progression and is prominently regulated by TGF-β signalling. Both EMT and TGF-β pathway components are tightly controlled by non-coding RNAs - including microRNAs (miRNAs), long non-coding RNAs (lncRNAs) and circular RNAs (circRNAs) - that collectively have major impacts on gene expression and resulting cellular states. While miRNAs are the best characterised regulators of EMT and TGF-β signaling and the miR-200-ZEB1/2 feedback loop plays a central role, important functions for lncRNAs and circRNAs are also now emerging. This review will summarise our current understanding of the roles of non-coding RNAs in EMT and TGF-β signaling with a focus on their functions in cancer progression.

LncRNAs in non-small cell lung cancer: novel diagnostic and prognostic biomarkers

Non-small cell lung cancer (NSCLC) is one of the main causes of cancer-related death worldwide, with a serious impact on human health and life. The identification of NSCLC at an early stage is a formidable task that frequently culminates in a belated diagnosis. LncRNA is a kind of noncoding RNA with limited protein-coding capacity, and its expression is out of balance in many cancers, especially NSCLC. A large number of studies have reported that lncRNA acts a vital role in regulating angiogenesis, invasion, metastasis, and the proliferation and apoptosis of tumor cells, affecting the occurrence and development of NSCLC. Abundant evidence demonstrates that lncRNAs may serve as potential biomarkers for NSCLC diagnosis and prognosis. In this review, we summarize the latest progress in characterizing the functional mechanism of lncRNAs involved in the development of NSCLC and further discuss the role of lncRNAs in NSCLC therapy and chemotherapy resistance. We also discuss the advantages, limitations, and challenges of using lncRNAs as diagnostic or prognostic biomarkers in the management of NSCLC.

Proactive and reactive roles of TGF-β in cancer

Cancer cells adapt to varying stress conditions to survive through plasticity. Stem cells exhibit a high degree of plasticity, allowing them to generate more stem cells or differentiate them into specialized cell types to contribute to tissue development, growth, and repair. Cancer cells can also exhibit plasticity and acquire properties that enhance their survival. TGF-β is an unrivaled growth factor exploited by cancer cells to gain plasticity. TGF-β-mediated signaling enables carcinoma cells to alter their epithelial and mesenchymal properties through epithelial-mesenchymal plasticity (EMP). However, TGF-β is a multifunctional cytokine; thus, the signaling by TGF-β can be detrimental or beneficial to cancer cells depending on the cellular context. Those cells that overcome the anti-tumor effect of TGF-β can induce epithelial-mesenchymal transition (EMT) to gain EMP benefits. EMP allows cancer cells to alter their cell properties and the tumor immune microenvironment (TIME), facilitating their survival. Due to the significant roles of TGF-β and EMP in carcinoma progression, it is essential to understand how TGF-β enables EMP and how cancer cells exploit this plasticity. This understanding will guide the development of effective TGF-β-targeting therapies that eliminate cancer cell plasticity.