Vimentin binds to a novel tumor suppressor protein, GSPT1-238aa, encoded by circGSPT1 with a selective encoding priority to halt autophagy in gastric carcinoma

CircRNA LOC729852 promotes bladder cancer progression by regulating macrophage polarization and recruitment via the miR-769-5p/IL-10 axis

Circular RNAs (circRNAs) function as tumour promoters or suppressors in bladder cancer (BLCA) by regulating genes involved in macrophage recruitment and polarization. However, the underlying mechanisms are largely unknown. The aim of this study was to determine the biological role of circLOC729852 in BLCA. CircLOC729852 was upregulated in BLCA tissues and correlated with increased proliferation, migration and epithelial mesenchymal transition (EMT) of BCLA cells. MiR-769-5p was identified as a target for circLOC729852, which can upregulate IL-10 expression by directly binding to and suppressing miR-769-5p. Furthermore, our results indicated that the circLOC729852/miR-769-5p/IL-10 axis modulates autophagy signalling in BLCA cells and promotes the recruitment and M2 polarization of TAMs by activating the JAK2/STAT3 signalling pathway. In addition, circLOC729852 also promoted the growth of BLCA xenografts and M2 macrophage infiltration in vivo. Thus, circLOC729852 functions as an oncogene in BLCA by inducing secretion of IL-10 by the M2 TAMs, which then facilitates tumour cell growth and migration. Taken together, circLOC729852 is a potential diagnostic biomarker and therapeutic target for BLCA.

Emerging roles of circular RNAs in tumorigenesis, progression, and treatment of gastric cancer

With an estimated one million new cases reported annually, gastric cancer (GC) ranks as the fifth most diagnosed malignancy worldwide. The early detection of GC remains a major challenge, and the prognosis worsens either when patients develop resistance to chemotherapy or radiotherapy or when the cancer metastasizes. The precise pathogenesis underlying GC is not well understood, which further complicates its treatment. Circular RNAs (circRNAs), a recently discovered class of noncoding RNAs that originate from parental genes through "back-splicing", have been shown to play a key role in various biological processes in both eukaryotes and prokaryotes. CircRNAs have been linked to cardiovascular diseases, diabetes, hypertension, Alzheimer's disease, and the occurrence and progression of tumors. Prior studies have established that circRNAs play a crucial role in GC, impacting tumorigenesis, diagnosis, progression, and therapy resistance. This review aims to summarize how circRNAs contribute to GC tumorigenesis and progression, examine their roles in the development of drug resistance, discuss their potential as biotechnological drugs, and summarize their response to therapeutic drugs and microorganism in GC.

Hypoxia-induced circ-CDYL-EEF1A2 transcriptional complex drives lung metastasis of cancer stem cells from hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is often associated with poor outcomes due to lung metastasis. ICAM-1+ circulating tumor cells, termed circulating cancer stem cells (CCSCs), possess stem cell-like characteristics. However, it is still unexplored how their presence indicates lung metastasis tendency, and particularly, what mechanism drives their lung metastasis. Here, we demonstrated that a preoperative CCSC count in 5 mL of blood (CCSC5) of >3 was a risk factor for lung metastasis in clinical HCC patients. The CSCs overexpressed with circ-CDYL entered the bloodstream and developed lung metastases in mice. Mechanistically, circ-CDYL promoted COL14A1 expression and thus ERK signaling to facilitate epithelial-mesenchymal transition. Furthermore, we uncovered that an RNA-binding protein, EEF1A2, acted as a novel transcriptional (co-) factor to cooperate with circ-CDYL and initiate COL14A1 transcription. A high circ-CDYL level is caused by HIF-1⍺-mediated transcriptional upregulation of its parental gene CDYL and splicing factor EIF4A3 under a hypoxia microenvironment. Hence, the hypoxia microenvironment enables the high-tendency lung metastasis of ICAM-1+ CCSCs through the HIF-1⍺/circ-CDYL-EEF1A2/COL14A1 axis, potentially allowing clinicians to preoperatively detect ICAM-1+ CCSCs as a real-time biomarker for precisely deciding HCC treatment strategies.

LINC01226 promotes gastric cancer progression through enhancing cytoplasm-to-nucleus translocation of STIP1 and stabilizing β-catenin protein

Gastric cancer (GC) remains one of the most common malignances and the leading cause of cancer-related mortality worldwide. Although the critical role of several long non-coding RNAs (lncRNAs) transcribed from several GC-risk loci has been established, we still know little about the biological significance of these lncRNAs at most gene loci and how they play in cell signaling. In the present study, we identified a novel oncogenic lncRNA LINC01226 transcribed from the 1p35.2 GC-risk locus. LINC01226 shows markedly higher expression levels in GC specimens compared with those in normal tissues. High expression of LINC01226 is evidently correlated with worse prognosis of GC cases. In line with these, oncogenic LINC01226 promotes proliferation, migration and metastasis of GC cells ex vivo and in vivo. Importantly, LINC01226 binds to STIP1 protein, leads to disassembly of the STIP1-HSP90 complex, elevates interactions between HSP90 and β-catenin, stabilizes β-catenin protein, activates the Wnt/β-catenin signaling and, thereby, promote GC progression. Together, our findings uncovered a novel layer regulating the Wnt signaling in cancers and uncovers a new epigenetic mode of GC tumorigenesis. These discoveries also shed new light on the importance of functional lncRNAs as innovative therapeutic targets through precisely controlling protein-protein interactions in cancers.

The ASH1L-AS1-ASH1L axis controls NME1-mediated activation of the RAS signaling in gastric cancer

Gastric cancer (GC) is one of the most leading cause of malignancies. However, the molecular mechanisms underlying stomach carcinogenesis remain incompletely understood. Dysregulated genetic and epigenetic alternations significantly contribute to GC development. Here, we report that ASH1L and its antisense lncRNA ASH1L-AS1, which are transcribed from the most significant GC-risk signal at 1q22, act as novel oncogenes. The high levels of ASH1L or lncRNA ASH1L-AS1 expression in GC specimens are associated with worse prognosis of patients. In line with this, ASH1L and ASH1L-AS1 are functionally important in promoting GC disease progression. LncRNA ASH1L-AS1 up-regulates ASH1L transcription, increases histone methyltransferase ASH1L expression and elevates genome-wide H3K4me3 modification levels in GC cells. Furthermore, ASH1L-AS1 directly interacts with transcription factor NME1 protein to form the ASH1L-AS1-NME1 ribonucleoprotein, which transcriptionally promotes expression of ASH1L, ASH1L-AS1, KRAS and RAF1, and activates the RAS signaling pathway in GC cells. Taken together, our data demonstrated that the ASH1L-AS1-ASH1L regulatory axis controls histone modification reprogram and activation of the RAS signaling in cancers. Thus, ASH1L-AS1 might be a novel targets of GC therapeutics and diagnosis in the clinic.

Newly discovered circRNAs encoding proteins: recent progress

Circular RNA (circRNA) is a special class of noncoding RNA molecules and the latest research hotspot in the field of RNA. CircRNA molecules have a closed loop structure, which is not affected by RNA exonuclease and has the characteristics of more stable expression. Previous studies have shown that circRNA molecules are rich in microRNA (miRNA) binding sites and act as miRNA sponges in cells. By interacting with miRNAs associated with tumors and other diseases, circRNAs play an important regulatory role. However, circRNAs have recently been found to have small open reading frames that enable them to encode peptides/proteins. These proteins have been reported to play an important role in the mechanism of regulation of a variety of diseases and have great potential in the diagnosis and treatment of diseases. In this review, we summarize the mechanism of action of the newly discovered circRNA-coding proteins since 2022 and briefly describe their research process. In addition, we also discuss the prediction model of the functional sites and encoded proteins of circRNAs, which provides a potential idea for future research on circRNAs.

Extracellular vesicles in gastric cancer: role of exosomal lncRNA and microRNA as diagnostic and therapeutic targets

Extracellular vesicles (EVs), including exosomes, play a crucial role in intercellular communication and have emerged as important mediators in the development and progression of gastric cancer. This review discusses the current understanding of the role of EVs, particularly exosomal lncRNA and microRNA, in gastric cancer and their potential as diagnostic and therapeutic targets. Exosomes are small membrane-bound particles secreted by both cancer cells and stromal cells within the tumor microenvironment. They contain various ncRNA and biomolecules, which can be transferred to recipient cells to promote tumor growth and metastasis. In this review, we highlighted the importance of exosomal lncRNA and microRNA in gastric cancer. Exosomal lncRNAs have been shown to regulate gene expression by interacting with transcription factors or chromatin-modifying enzymes, which regulate gene expression by binding to target mRNAs. We also discuss the potential use of exosomal lncRNAs and microRNAs as diagnostic biomarkers for gastric cancer. Exosomes can be isolated from various bodily fluids, including blood, urine, and saliva. They contain specific molecules that reflect the molecular characteristics of the tumor, making them promising candidates for non-invasive diagnostic tests. Finally, the potential of targeting exosomal lncRNAs and microRNAs as a therapeutic strategy for gastric cancer were reviewed as wee. Inhibition of specific molecules within exosomes has been shown to suppress tumor growth and metastasis in preclinical models. In conclusion, this review article provides an overview of the current understanding of the role of exosomal lncRNA and microRNA in gastric cancer. We suggest that further research into these molecules could lead to new diagnostic tools and therapeutic strategies for this deadly disease.

CircRNAs regulate the crosstalk between inflammation and tumorigenesis: The bilateral association and molecular mechanisms

Inflammation, a hallmark of cancer, has been associated with tumor progression, transition into malignant phenotype and efficacy of the chemotherapeutic agents in cancer. Chronic inflammation provides a favorable environment for tumorigenesis by inducing immunosuppression, whereas acute inflammation prompts tumor suppression by generating anti-tumor immune responses. Inflammatory factors derived from interstitial cells or tumor cells can stimulate cell proliferation and survival by modulating oncogenes and/or tumor suppressors. Recently, a new class of RNAs, i.e., circular RNAs (circRNAs), has been implicated in inflammatory diseases. Although there are reports on circRNAs imparting functions in inflammatory insults, whether these circularized transcripts hold the potential to regulate inflammation-induced cancer or tumor-related inflammation, and modulate the interactions between tumor microenvironment (TME) and the inflammatory stromal/immune cells, awaits further elucidation. Contextually, the current review describes the molecular association between inflammation and cancer, and spotlights the regulatory mechanisms by which circRNAs can moderate TME in response to inflammatory signals/triggers. We also present comprehensive information about the immune cell(s)-specific expression and functions of the circRNAs in TME, modulation of inflammatory signaling pathways to drive tumorigenesis, and their plausible roles in inflammasomes and tumor development. Moreover, the therapeutic potential of these circRNAs in harnessing inflammatory responses in cancer is also discussed.

Newly discovered mechanisms that mediate tumorigenesis and tumour progression: circRNA-encoded proteins

Proteins produced by cap-independent translation mediated by an internal ribosome entry site (IRES) in circular RNAs (circRNAs) play important roles in tumour progression. To date, numerous studies have been performed on circRNAs and the proteins they encode. In this review, we summarize the biogenesis of circRNAs and the mechanisms regulating circRNA-encoded proteins expression. We also describe relevant research methods and their applications to biological processes such as tumour cell proliferation, metastasis, epithelial-mesenchymal transition (EMT), apoptosis, autophagy and chemoresistance. This paper offers deeper insights into the roles that circRNA-encoded proteins play in tumours. It also provides a theoretical basis for the use of circRNA-encoded proteins as biomarkers of tumorigenesis and for the development of new targets for tumour therapy.

BmNPV circular RNA-encoded peptide VSP39 promotes viral replication

CircRNAs are covalently closed single-stranded circular RNA molecules, which are not easily degraded by endonucleases and play vital roles in many biological processes. Currently, most studies on circRNAs focus on endogenous circRNAs in cells, and there are few studies on virus-encoded circRNAs. In this study, a viral circRNA (circRNA-000010) derived from the region (-/bp: 114514-115,319) of the complementary strand of Bombyx mori Nucleopolyhedrovirus (BmNPV) genome was identified with the circRNA-sequencing. The authenticity of viral circRNA-000010 was further confirmed by reverse transcription PCR, reverse transcription-rolling circle amplification (TCA), in situ hybridization, immunofluorescent staining, and Northern blotting. The results of overexpression and knockdown experiments showed that circRNA-000010 promoted viral replication. Furthermore, a viral small peptide VSP39 with 39 amino acid residues translated by circRNA-000010 but not its linear molecule was confirmed. Finally, VSP39 was found to promote viral replication. Our findings indicated that a viral circRNA encoded by BmNPV promoted viral replication. These findings will provide new clues for further understanding coding information of the BmNPV genome and open a new insight for investigating host-virus interactions.

Role of circRNAs in gastric cancer

Circular RNAs (circRNAs) are a large class of non-coding RNAs with single-strand covalently closed loops, formed by reverse splicing, which widely exist in many cell lines and diverse species. Some circRNAs have highly evolutionarily conserved sequences, or tissue-specific or cell-specific expression patterns, and many circRNAs are extremely stable. In the past decades, accumulating evidence has indicated that circRNAs participate in the mechanisms associated with the development of many kinds of tumors, exert important biological functions by acting as microRNA or protein ‘sponges’, transcriptional regulatory factors, and protein translation templates, and play key roles in the occurrence and development of gastric cancer. This review comprehensively summarizes the biogenesis, characteristics, and biological functions of circRNAs, and the molecular mechanisms underlying the role of circRNAs in the carcinogenesis and progression of gastric cancer.

Silencing effects of mutant RAS signalling on transcriptomes

Mutated genes of the RAS family encoding small GTP-binding proteins drive numerous cancers, including pancreatic, colon and lung tumors. Besides the numerous effects of mutant RAS gene expression on aberrant proliferation, transformed phenotypes, metabolism, and therapy resistance, the most striking consequences of chronic RAS activation are changes of the genetic program. By performing systematic gene expression studies in cellular models that allow comparisons of pre-neoplastic with RAS-transformed cells, we and others have estimated that 7 percent or more of all transcripts are altered in conjunction with the expression of the oncogene. In this context, the number of up-regulated transcripts approximates that of down-regulated transcripts. While up-regulated transcription factors such as MYC, FOSL1, and HMGA2 have been identified and characterized as RAS-responsive drivers of the altered transcriptome, the suppressed factors have been less well studied as potential regulators of the genetic program and transformed phenotype in the breadth of their occurrence. We therefore have collected information on downregulated RAS-responsive factors and discuss their potential role as tumor suppressors that are likely to antagonize active cancer drivers. To better understand the active mechanisms that entail anti-RAS function and those that lead to loss of tumor suppressor activity, we focus on the tumor suppressor HREV107 (alias PLAAT3 [Phospholipase A and acyltransferase 3], PLA2G16 [Phospholipase A2, group XVI] and HRASLS3 [HRAS-like suppressor 3]). Inactivating HREV107 mutations in tumors are extremely rare, hence epigenetic causes modulated by the RAS pathway are likely to lead to down-regulation and loss of function.

Circular RNAs as diagnostic biomarkers for gastric cancer: A comprehensive update from emerging functions to clinical significances

The incidence and mortality of gastric cancer ranks as a fouth leading cause of cancer death worldwide, especially in East Asia. Due to the lack of specific early-stage symptoms, the majority of patients in most developing nations are diagnosed at an advanced stage. Therefore, it is urgent to find more sensitive and reliable biomarkers for gastric cancer screening and diagnosis. Circular RNAs (circRNAs), a novel type of RNAs with covalently closed loops, are becoming a latest hot spot in the field of. In recent years, a great deal of research has demonstrated that abnormal expression of circRNAs was associated with the development of gastric cancer, and suggested that circRNA might serve as a potential biomarker for gastric cancer diagnosis. In this review, we summarize the structural characteristics, formation mechanism and biological function of circRNAs, and elucidate research progress and existing problems in early screening of gastric cancer.