Long noncoding RNA LINC01594 inhibits the CELF6-mediated splicing of oncogenic CD44 variants to promote colorectal cancer metastasis

The role of RNA binding proteins in cancer biology: A focus on FMRP

RNA-binding proteins (RBPs) act as crucial regulators of gene expression within cells, exerting precise control over processes such as RNA splicing, transport, localization, stability, and translation through their specific binding to RNA molecules. The diversity and complexity of RBPs are particularly significant in cancer biology, as they directly impact a multitude of RNA metabolic events closely associated with tumor initiation and progression. The fragile X mental retardation protein (FMRP), as a member of the RBP family, is central to the neurodevelopmental disorder fragile X syndrome and increasingly recognized in the modulation of cancer biology through its influence on RNA metabolism. The protein's versatility, stemming from its diverse RNA-binding domains, enables it to govern a wide array of transcript processing events. Modifications in FMRP's expression or localization have been associated with the regulation of mRNAs linked to various processes pertinent to cancer, including tumor proliferation, metastasis, epithelial-mesenchymal transition, cellular senescence, chemotherapy/radiotherapy resistance, and immunotherapy evasion. In this review, we emphasize recent findings and analyses that suggest contrasting functions of this protein family in tumorigenesis. Our knowledge of the proteins that are regulated by FMRP is rapidly growing, and this has led to the identification of multiple targets for therapeutic intervention of cancer, some of which have already moved into clinical trials or clinical practice.

LncRNA MRF targeting FSHR inhibits the osteogenic differentiation of BMSCs and bone defect repair through the regulation of the cAMP-PKA-CREB signaling pathway

BACKGROUND

Mesenchymal stem cells (MSCs), known for their ability to differentiate into osteoblasts, play a pivotal role in bone metabolism. In our previous investigations, we identified a novel long non-coding RNA (lncRNA) named MCP1 Regulatory Factor (MRF), which exhibits significant involvement in immune regulation of BMSCs. Moreover, we observed noticeable expression changes of MRF during the osteogenic differentiation of BMSCs. However, the exact role and underlying mechanism of MRF in the osteogenic differentiation of BMSCs remain elusive.

METHODS

QRT-PCR analysis was employed to assess the expression levels of MRF. RNA interference and overexpression plasmids were utilized to modulate MRF expression, allowing for the observation of changes in the osteogenic differentiation capacity of BMSCs. Downstream pathways involved in the MRF-mediated regulation of BMSCs' osteogenic differentiation were predicted using transcriptome sequencing. The functionality of MRF in vivo was validated through a mouse tibial drilling defect model.

RESULTS

In patients with osteoporosis, there is a notable increase in the expression of MRF within BMSCs. During the osteogenic differentiation of BMSCs, the MRF expression progressively decreases. The knockdown of MRF significantly enhances the osteogenic differentiation of BMSCs, promoting an increased expression of bone-related proteins such as RUNX2, ALP, and COL1A1. Transcriptome sequencing and western blot indicated that cAMP/PKA/CREB signaling pathway was significantly activated after lncRNA-MRF knockdown. Moreover, in the mouse tibial drilling defect model, MRF knockdown significantly promotes ossification in vivo.

CONCLUSIONS

MRF modulates the cAMP/PKA/CREB signaling pathway via the follicle stimulating hormone receptor (FSHR), thereby influencing the ossification differentiation of BMSCs. Our research suggests that MRF may serve as a potential target for bone-related disorders.

CELF6 as an Oncogene in Colorectal Cancer: Targeting Stem-Cell-Like Properties Through Modulation of HOXA5 mRNA Stability

BACKGROUND

Emerging evidence indicates the essential role of cancer stem cells (CSCs) in the development and progression of various cancers, including colorectal cancer (CRC). CELF6, a member of the cytosine-uridine-guanine-binding protein (CUG-BP), Elav-like family (CELF), has been reported to be downregulated in CRC tissues. This study aims to elucidate the role and underlying mechanisms of CELF6 in CRC progression.

METHODS

The expression levels and prognostic significance of CELF6, along with its association with homeobox A5 (HOXA5), were analyzed using University of Alabama at Birmingham Cancer Data Analysis Portal (UALCAN), PrognoScan, and Tumor Immune Estimation Resource (TIMER) databases. The expression of CELF6 was further assessed through quantitative real-time polymerase chain reaction (qRT-PCR), immunoblotting, and immunohistochemistry. Both in vitro and in vivo experiments were conducted to investigate the effects of CELF6 on CRC cell proliferation, stemness and tumorigenesis, and to elucidate the molecular mechanisms.

RESULTS

CELF6 was found to be downregulated in CRC and was associated with poor prognosis. Functional studies revealed that overexpression of CELF6 resulted in decreased CRC cell proliferation and stemness in vitro, reduced tumor growth in vivo, and induced G1 phase cell cycle arrest. Mechanistically, CELF6 regulated the expression of HOXA5 by modulating its mRNA stability. Furthermore, the knockdown of HOXA5 reversed the inhibitory effects of CELF6 on CRC cell proliferation and stemness, demonstrating that silencing HOXA5 counteracted the suppressive effects of CELF6.

CONCLUSIONS

This study is the first to identify CELF6 as a suppressor of stemness and a modulator of CRC progression. These findings provide new insights into the role of CELF6 in CRC and highlight its potential as a novel therapeutic target.

A novel lncRNA LOC101928222 promotes colorectal cancer angiogenesis by stabilizing HMGCS2 mRNA and increasing cholesterol synthesis

BACKGROUND

Metastasis is the leading cause of mortality in patients with colorectal cancer (CRC) and angiogenesis is a crucial factor in tumor invasion and metastasis. Long noncoding RNAs (lncRNAs) play regulatory functions in various biological processes in tumor cells, however, the roles of lncRNAs in CRC-associated angiogenesis remain to be elucidated in CRC, as do the underlying mechanisms.

METHODS

We used bioinformatics to screen differentially expressed lncRNAs from TCGA database. LOC101928222 expression was assessed by qRT-PCR. The impact of LOC101928222 in CRC tumor development was assessed both in vitro and in vivo. The regulatory mechanisms of LOC101928222 in CRC were investigated by cellular fractionation, RNA-sequencing, mass spectrometric, RNA pull-down, RNA immunoprecipitation, RNA stability, and gene-specific m6A assays.

RESULTS

LOC101928222 expression was upregulated in CRC and was correlated with a worse outcome. Moreover, LOC101928222 was shown to promote migration, invasion, and angiogenesis in CRC. Mechanistically, LOC101928222 synergized with IGF2BP1 to stabilize HMGCS2 mRNA through an m6A-dependent pathway, leading to increased cholesterol synthesis and, ultimately, the promotion of CRC development.

CONCLUSIONS

In summary, these findings demonstrate a novel, LOC101928222-based mechanism involved in the regulation of cholesterol synthesis and the metastatic potential of CRC. The LOC101928222-HMGCS2-cholesterol synthesis pathway may be an effective target for diagnosing and managing CRC metastasis.

The m6A modification mediated-lncRNA POU6F2-AS1 reprograms fatty acid metabolism and facilitates the growth of colorectal cancer via upregulation of FASN

BACKGROUND

Long noncoding RNAs (lncRNAs) have emerged as key players in tumorigenesis and tumour progression. However, the biological functions and potential mechanisms of lncRNAs in colorectal cancer (CRC) are unclear.

METHODS

The novel lncRNA POU6F2-AS1 was identified through bioinformatics analysis, and its expression in CRC patients was verified via qRT-PCR and FISH. In vitro and in vivo experiments, such as BODIPY staining, Oil Red O staining, triglyceride (TAG) assays, and liquid chromatography mass spectrometry (LC-MS) were subsequently performed with CRC specimens and cells to determine the clinical significance, and functional roles of POU6F2-AS1. Biotinylated RNA pull-down, RIP, Me-RIP, ChIP, and patient-derived organoid (PDO) culture assays were performed to confirm the underlying mechanism of POU6F2-AS1.

RESULTS

The lncRNA POU6F2-AS1 is markedly upregulated in CRC and associated with adverse clinicopathological features and poor overall survival in CRC patients. Functionally, POU6F2-AS1 promotes the growth and lipogenesis of CRC cells both in vitro and in vivo. Mechanistically, METTL3-induced m6A modification is involved in the upregulation of POU6F2-AS1. Furthermore, upregulated POU6F2-AS1 could tether YBX1 to the FASN promoter to induce transcriptional activation, thus facilitating the growth and lipogenesis of CRC cells.

CONCLUSIONS

Our data revealed that the upregulation of POU6F2-AS1 plays a critical role in CRC fatty acid metabolism and might provide a novel promising biomarker and therapeutic target for CRC.