Long Noncoding RNA NEAT1 Contributes to the Tumorigenesis of Colorectal Cancer Through Regulating SLC38A1 Expression by Sponging miR-138

The paradox of autophagy in cancer: NEAT1's role in tumorigenesis and therapeutic resistance

Cancer remains a current active problem of modern medicine, a process during which cell growth and proliferation become uncontrolled. However, the role of autophagy in the oncological processes is counterintuitive and, at the same time, increasingly influential on the formation, development, and response to therapy of oncological diseases. Autophagy is a vital cellular process that removes defective proteins and organelles and supports cellular homeostasis. Autophagy can enhance the ability to form new tumors and suppress this formation in cancer. The dual potential of apoptosis may be the reason for this duality in either promoting or impeding the survival of cancer cells, depending on the situation, including starvation or treatment stress. Furthermore, long non-coding RNA NEAT1, which has been linked to several stages of carcinogenesis and in all forms of the illness, has drawn attention as a major player in cancer biology. NEAT1 is a structural portion of nuclear paraspeckles and has roles in deactivating expression in both transcriptional and post-transcriptional levels. NEAT1 acts in carcinogenesis in numerous ways, comprising interactions with microRNAs, the influence of gene articulation, regulation of epigenetics, and engagement in signalling cascades. In addition, the complexity of NEAT1's role in cancer occurrence is amplified by its place in regulating cancer stem cells and the tumor microenvironment. NEAT1's interaction with autophagy further complicates the already complicated function of this RNA in cancer biology. NEAT1 has been linked to autophagy in several types of cancer, influencing autophagy pathways and altering its stress response and tumor cell viability. Understanding the interrelation between NEAT1, autophagy, and cancer will enable practitioners to identify novel treatment targets and approaches to disrupt oncogenic processes, reduce the occurrence of treatment resistance, and increase patient survival rates. Specialized treatment strategies and regimens are thus achievable. In the present review, the authors analyze sophisticated relationship schemes in cancer: The NEAT1 pathway and the process of autophagy.

MicroRNAs in the Regulation of Solute Carrier Proteins Behind Xenobiotic and Nutrient Transport in Cells

Altered metabolism, such as aerobic glycolysis or the Warburg effect, has been recognized as characteristics of tumor cells for almost a century. Since then, there is accumulating evidence to demonstrate the metabolic reprogramming of tumor cells, addiction to excessive uptake and metabolism of key nutrients, to support rapid proliferation and invasion under tumor microenvironment. The solute carrier (SLC) superfamily transporters are responsible for influx or efflux of a wide variety of xenobiotic and metabolites that are needed for the cells to function, as well as some medications. To meet the increased demand for nutrients and energy, SLC transporters are frequently dysregulated in cancer cells. The SLCs responsible for the transport of key nutrients for cancer metabolism and energetics, such as glucose and amino acids, are of particular interest for their roles in tumor progression and metastasis. Meanwhile, rewired metabolism is accompanied by the dysregulation of microRNAs (miRNAs or miRs) that are small, noncoding RNAs governing posttranscriptional gene regulation. Studies have shown that many miRNAs directly regulate the expression of specific SLC transporters in normal or diseased cells. Changes of SLC transporter expression and function can subsequently alter the uptake of nutrients or therapeutics. Given the important role for miRNAs in regulating disease progression, there is growing interest in developing miRNA-based therapies, beyond serving as potential diagnostic or prognostic biomarkers. In this article, we discuss how miRNAs regulate the expression of SLC transporters and highlight potential influence on the supply of essential nutrients for cell metabolism and drug exposure toward desired efficacy.

Emerging roles for lncRNA-NEAT1 in colorectal cancer

Colorectal cancer (CRC) is the third cause of cancer death in the world that arises from the glandular and epithelial cells of the large intestine, during a series of genetic or epigenetic alternations. Recently, long non-coding RNAs (lncRNAs) has opened a separate window of research in molecular and translational medicine. Emerging evidence has supported that lncRNAs can regulate cell cycle of CRC cells. LncRNA NEAT1 has been verified to participate in colon cancer development and progression. NEAT1 as a competing endogenous RNA could suppress the expression of miRNAs, and then regulate molecules downstream of these miRNAs. In this review, we summarized emerging roles of NEAT1 in CRC cells.

NEAT1 as a competing endogenous RNA in tumorigenesis of various cancers: Role, mechanism and therapeutic potential

The nuclear paraspeckle assembly transcript 1 (NEAT1) is a long non-coding RNA (lncRNA) that is upregulated in a variety of human cancer types. Increasing evidence has shown that the elevation of NEAT1 in cancer cells promotes cell growth, migration, and invasion and inhibits cell apoptosis. It is also known that lncRNAs act as a competing endogenous RNA (ceRNA) by sponging microRNAs (miRNAs) to alter the expression levels of their target genes in the development of cancers. Therefore, it is important to understand the molecular mechanisms underlying this observation. In this review, specific emphasis was placed on NEAT1's role in tumor development. We also summarize and discuss the feedback roles of NEAT1/miRNA/target network in the progression of various cancers. As our understanding of the role of NEAT1 during tumorigenesis improves, its therapeutic potential as a biomarker and/or target for cancer also becomes clearer.

NEAT1 silencing alleviates pulmonary arterial smooth muscle cell migration and proliferation under hypoxia through regulation of miR‑34a‑5p/KLF4 in vitro

Pulmonary arterial hypertension (PAH) is a severe vascular disease that adversely affects patient health and can be life threatening. The present study aimed to investigate the detailed role of nuclear paraspeckle assembly transcript 1 (NEAT1) in PAH. Using RT‑qPCR, the expression levels of NEAT1, microRNA (miR)‑34a‑5p, and Krüppel‑like factor 4 (KLF4) were detected in both hypoxia‑treated pulmonary arterial smooth muscle cells (PASMCs) and serum from PAH patients. Then, the interactions among miR‑34a‑5p, NEAT1, and KLF4 were evaluated by dual‑luciferase reporter assay. The detailed role of the NEAT1/miR‑34a‑5p/KLF4 axis in PAH pathogenesis was further explored using MTT, Transwell, and western blot assays. The results revealed that NEAT1 targeted miR‑34a‑5p and miR‑34a‑5p targeted KLF4. In hypoxia‑treated PASMCs and serum from PAH patients, high NEAT1 and KLF4 expression levels and low miR‑34a‑5p expression were observed. The proliferation and migration of hypoxia‑treated PASMCs were reduced by transfection with sh‑NEAT1 or miR‑34a‑5p mimics. The suppressive effects of NEAT1 knockdown on the proliferation and migration of hypoxia‑treated PASMCs were reversed by knock down of miR‑34a‑5p expression and increased KLF4 expression. NEAT1 was not only highly expressed in the serum of PAH patients but its silencing also alleviated PAH by regulating miR‑34a‑5p/KLF4 in vitro. The present study highlighted a potential new therapeutic target and diagnostic biomarker for PAH.

CircRUNX1 functions as an oncogene in colorectal cancer by regulating circRUNX1/miR-485-5p/SLC38A1 axis

BACKGROUND

Circular RNAs (circRNAs) have emerged as vital regulators in human cancers, including colorectal cancer (CRC). In this study, we aimed to explore the roles of circRUNX1 in CRC.

METHODS

The levels of circRUNX1, RUNX1 mRNA, solute carrier family 38 member 1 (SLC38A1) mRNA and microRNA-485-5p (miR-485-5p) were determined by quantitative real-time polymerase chain reaction (qRT-PCR) analysis. The protein level of SLC38A1 was measured by Western blot assay. Cell colony formation, migration, invasion and apoptosis were assessed by colony formation assay, wound-healing assay, Transwell assay and flow cytometry analysis, respectively. The interaction between miR-485-5p and circRUNX1 or SLC38A1 was verified by dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assay. The levels of extracellular glutamine, intracellular glutamate and α-ketoglutarate (α-KG) were measured with specific kits. The functional role of circRUNX1 in CRC development in vivo was explored by murine xenograft model assay.

RESULTS

CircRUNX1 was upregulated in CRC tissues and cells compared with normal tissues and cells. CircRUNX1 deficiency restrained CRC cell colony formation, migration, invasion and glutaminolysis and induced apoptosis in vitro as well as blocked tumour growth in vivo. CircRUNX1 directly sponged miR-485-5p, which negatively modulated SLC38A1 expression in CRC cells. The effects of circRUNX1 knockdown on CRC cell colony formation, migration, invasion, apoptosis and glutaminolysis were reversed by miR-485-5p inhibition. Moreover, miR-485-5p overexpression repressed the malignant behaviours of CRC cells, with SLC38A1 elevation overturned the impacts.

CONCLUSION

CircRUNX1 promoted CRC cell growth, metastasis and glutamine metabolism and repressed apoptosis by elevating SLC38A1 through sponging miR-485-5p, which might provide a novel target for CRC treatment.