A 5'-tRNA halve, tiRNA-Gly promotes cell proliferation and migration via binding to RBM17 and inducing alternative splicing in papillary thyroid cancer

The potential role of differentially expressed tRNA-derived fragments in high glucose-induced podocytes

The prevalence of diabetic kidney disease (DKD) is increasing annually. Damage to and loss of podocytes occur early in DKD. tRNA-derived fragments (tRFs), originating from tRNA precursors or mature tRNAs, are associated with various illnesses. In this study, tRFs were identified, and their roles in podocyte injury induced by high-glucose (HG) treatment were explored. High-throughput sequencing of podocytes treated with HG was performed to identify differentially expressed tRFs. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were performed. The expression levels of nephrin, podocin, and desmin were measured in podocytes after overexpression of tRF-1:24-Glu-CTC-1-M2 (tRF-1:24) and concomitant HG treatment. A total of 647 tRFs were identified, and 89 differentially expressed tRFs (|log2FC| ≥ 0.585; p ≤ .05) were identified in the HG group, of which 53 tRFs were downregulated and 36 tRFs were upregulated. The 10 tRFs with the highest differential expression were detected by real-time quantitative polymerase chain reaction (RT-qPCR), and these results were consistent with the sequencing results. GO analysis revealed that the biological process, cellular component, and molecular function terms in which the tRFs were the most enriched were cellular processes, cellular anatomical entities, and binding. KEGG pathway analysis revealed that tRFs may be involved in signaling pathways related to growth hormones, phospholipase D, the regulation of stem cell pluripotency, and T-/B-cell receptors. Overexpression of tRF-1:24, one of the most differentially expressed tRFs, attenuated podocyte injury induced by HG. Thus, tRFs might be potential biomarkers for podocyte injury in DKD.

tRNA-derived fragments: Unveiling new roles and molecular mechanisms in cancer progression

tRNA-derived fragments (tRFs) are novel small noncoding RNAs (sncRNAs) that range from approximately 14 to 50 nt. They are generated by the cleavage of mature tRNAs or precursor tRNAs (pre-tRNAs) at specific sites. Based on their origin and length, tRFs can be classified into three categories: (1) tRF-1 s; (2) tRF-3 s, tRF-5 s, and internal tRFs (i-tRFs); and (3) tRNA halves. They play important roles in stress response, signal transduction, and gene expression processes. Recent studies have identified differential expression of tRFs in various tumors. Aberrantly expressed tRFs have critical clinical value and show promise as new biomarkers for tumor diagnosis and prognosis and as therapeutic targets. tRFs regulate the malignant progression of tumors via various mechanisms, primarily including modulation of noncoding RNA biogenesis, global chromatin organization, gene expression regulation, modulation of protein translation, regulation of epigenetic modification, and alternative splicing regulation. In conclusion, tRF-mediated regulatory pathways could present new avenues for tumor treatment, and tRFs could serve as promising therapeutic targets for cancer therapy.

Characterization of RNA Processing Genes in Colon Cancer for Predicting Clinical Outcomes

Objective

Colon cancer is associated with multiple levels of molecular heterogeneity. RNA processing converts primary transcriptional RNA to mature RNA, which drives tumourigenesis and its maintenance. The characterisation of RNA processing genes in colon cancer urgently needs to be elucidated.

Methods

In this study, we obtained 1033 relevant samples from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases to explore the heterogeneity of RNA processing phenotypes in colon cancer. Firstly, Unsupervised hierarchical cluster analysis detected 4 subtypes with specific clinical outcomes and biological features via analysis of 485 RNA processing genes. Next, we adopted the least absolute shrinkage and selection operator (LASSO) as well as Cox regression model with penalty to characterise RNA processing-related prognostic features.

Results

An RNA processing-related prognostic risk model based on 10 genes including FXR1, MFAP1, RBM17, SAGE1, SNRPA1, SRRM4, ADAD1, DDX52, ERI1, and EXOSC7 was identified finally. A composite prognostic nomogram was constructed by combining this feature with the remaining clinical variables including TNM, age, sex, and stage. Genetic variation, pathway activation, and immune heterogeneity with risk signatures were also analysed via bioinformatics methods. The outcomes indicated that the high-risk subgroup was associated with higher genomic instability, increased proliferative and cycle characteristics, decreased tumour killer CD8+ T cells and poorer clinical prognosis than the low-risk group.

Conclusion

This prognostic classifier based on RNA-edited genes facilitates stratification of colon cancer into specific subgroups according to TNM and clinical outcomes, genetic variation, pathway activation, and immune heterogeneity. It can be used for diagnosis, classification and targeted treatment strategies comparable to current standards in precision medicine. It provides a rationale for elucidation of the role of RNA editing genes and their clinical significance in colon cancer as prognostic markers.

A Novel tsRNA, m7G-3' tiRNA LysTTT, Promotes Bladder Cancer Malignancy Via Regulating ANXA2 Phosphorylation

Emerging evidence indicates that transfer RNA (tRNA)-derived small RNAs (tsRNAs), originated from tRNA with high abundance RNA modifications, play an important role in many complex physiological and pathological processes. However, the biological functions and regulatory mechanisms of modified tsRNAs in cancer remain poorly understood. Here, it is screened for and confirmed the presence of a novel m7G-modified tsRNA, m7G-3'-tiRNA LysTTT (mtiRL), in a variety of chemical carcinogenesis models by combining small RNA sequencing with an m7G small RNA-modified chip. Moreover, it is found that mtiRL, catalyzed by the tRNA m7G-modifying enzyme mettl1, promotes bladder cancer (BC) malignancy in vitro and in vivo. Mechanistically, mtiRL is found to specifically bind the oncoprotein Annexin A2 (ANXA2) to promote its Tyr24 phosphorylation by enhancing the interactions between ANXA2 and Yes proto-oncogene 1 (Yes1), leading to ANXA2 activation and increased p-ANXA2-Y24 nuclear localization in BC cells. Together, these findings define a critical role for mtiRL and suggest that targeting this novel m7G-modified tsRNA can be an efficient way for to treat BC.

tRF-29-79 regulates lung adenocarcinoma progression through mediating glutamine transporter SLC1A5

In recent decades, considerable evidence has emerged indicating the involvement of tRNA-derived fragments (tRFs) in cancer progression through various mechanisms. However, the biological effects and mechanisms of tRFs in lung adenocarcinoma (LUAD) remain unclear. In this study, we screen out tRF-29-79, a 5'-tRF derived from tRNAGlyGCC, through profiling the tRF expressions in three pairs of LUAD tissues. We show that tRF-29-79 is downregulated in LUAD and downregulation of tRF-29-79 is associated with poorer prognosis. In vivo and in vitro assay reveal that tRF-29-79 inhibits proliferation, migration and invasion of LUAD cells. Mechanistically, we discovered that tRF-29-79 interacts with the RNA-binding protein PTBP1 and facilitates the transportation of PTBP1 from nucleus to cytoplasm, which regulates alternative splicing in the 3' untranslated region (UTR) of SLC1A5 pre-mRNA. Given that SLC1A5 is a core transporter of glutamine, we proved that tRF-29-79 mediate glutamine metabolism of LUAD through affecting the stability of SLC1A5 mRNA, thus exerts its anticancer function. In summary, our findings uncover the novel mechanism that tRF-29-79 participates in glutamine metabolism through interacting with PTBP1 and regulating alternative splicing in the 3' UTR of SLC1A5 pre-mRNA.

tiRNA-Val-CAC-2 interacts with FUBP1 to promote pancreatic cancer metastasis by activating c‑MYC transcription

Cumulative studies have established the significance of transfer RNA-derived small RNA (tsRNA) in tumorigenesis and progression. Nevertheless, its function and mechanism in pancreatic cancer metastasis remain largely unclear. Here, we screened and identified tiRNA-Val-CAC-2 as highly expressed in pancreatic cancer metastasis samples by tsRNA sequencing. We also observed elevated levels of tiRNA-Val-CAC-2 in the serum of pancreatic cancer patients who developed metastasis, and patients with high levels of tiRNA-Val-CAC-2 exhibited a worse prognosis. Additionally, knockdown of tiRNA-Val-CAC-2 inhibited the metastasis of pancreatic cancer in vivo and in vitro, while overexpression of tiRNA-Val-CAC-2 promoted the metastasis of pancreatic cancer. Mechanically, we discovered that tiRNA-Val-CAC-2 interacts with FUBP1, leading to enhanced stability of FUBP1 protein and increased FUBP1 enrichment in the c-MYC promoter region, thereby boosting the transcription of c-MYC. Of note, rescue experiments confirmed that tiRNA-Val-CAC-2 could influence pancreatic cancer metastasis via FUBP1-mediated c-MYC transcription. These findings highlight a potential novel mechanism underlying pancreatic cancer metastasis, and suggest that both tiRNA-Val-CAC-2 and FUBP1 could serve as promising prognostic biomarkers and potential therapeutic targets for pancreatic cancer.

tRNA-derived fragments: Key determinants of cancer metastasis with emerging therapeutic and diagnostic potentials

Metastasis is a significant clinical challenge responsible for cancer mortality and non-response to treatment. However, the molecular mechanisms driving metastasis remain unclear, limiting the development of efficient diagnostic and therapeutic approaches. Recent breakthroughs in cancer biology have discovered a group of small non-coding RNAs called tRNA-derived fragments (tRFs), which play a critical role in the metastatic behavior of various tumors. tRFs are produced from cleavage modifications of tRNAs and have different functional classes based on the pattern of these modifications. They perform post-transcriptional regulation through microRNA-like functions, displacing RNA-binding proteins, and play a role in translational regulation by inducing ribosome synthesis, translation initiation, and epigenetic regulation. Tumor cells manipulate tRFs to develop and survive the tumor mass, primarily by inducing metastasis. Multiple studies have demonstrated the potential of tRFs as therapeutic, diagnostic, and prognostic targets for tumor metastasis. This review discusses the production and function of tRFs in cells, their aberrant molecular contributions to the metastatic environment, and their potential as promising targets for anti-metastasis treatment strategies.

tRF-1:30-Gly-CCC-3 inhibits thyroid cancer via binding to PC and modulating metabolic reprogramming

tRFs and tiRNAs (tRNA-derived fragments) are an emerging class of small noncoding RNAs produced by the precise shearing of tRNAs in response to specific stimuli. They have been reported to regulate the pathological processes of numerous human cancers. However, the biofunction of tRFs and tiRNAs in the development and progression of papillary thyroid cancer (PTC) has not been reported yet. In this study, we aimed to explore the biological roles of tRFs and tiRNAs in PTC and discovered that a novel 5'tRNA-derived fragment called tRF-1:30-Gly-CCC-3 (tRF-30) was markedly down-regulated in PTC tissues and cell lines. Functionally, tRF-30 inhibited the proliferation and invasion of PTC cells. Mechanistically, tRF-30 directly bound to the biotin-dependent enzyme pyruvate carboxylase (PC), downregulated its protein level, interfered with the TCA cycle intermediate anaplerosis, and thus affected metabolic reprogramming and PTC progression. These findings revealed a novel regulatory mechanism for tRFs and a potential therapeutic target for PTC.

tRNA-Derived Small RNAs: A Novel Regulatory Small Noncoding RNA in Renal Diseases

Background

tRNA-derived small RNAs (tsRNAs) are an emerging class of small noncoding RNAs derived from tRNA cleavage.

Summary

With the development of high-throughput sequencing, various biological roles of tsRNAs have been gradually revealed, including regulation of mRNA stability, transcription, translation, direct interaction with proteins and as epigenetic factors, etc. Recent studies have shown that tsRNAs are also closely related to renal disease. In clinical acute kidney injury (AKI) patients and preclinical AKI models, the production and differential expression of tsRNAs in renal tissue and plasma were observed. Decreased expression of tsRNAs was also found in urine exosomes from chronic kidney disease patients. Dysregulation of tsRNAs also appears in models of nephrotic syndrome and patients with lupus nephritis. And specific tsRNAs were found in high glucose model in vitro and in serum of diabetic nephropathy patients. In addition, tsRNAs were also differentially expressed in patients with kidney cancer and transplantation.

Key Messages

In the present review, we have summarized up-to-date works and reviewed the relationship and possible mechanisms between tsRNAs and kidney diseases.

Transfer RNAs as dynamic and critical regulators of cancer progression

Transfer RNAs (tRNAs) have been historically viewed as non-dynamic adaptors that decode the genetic code into proteins. Recent work has uncovered dynamic regulatory roles for these fascinating molecules. Advances in tRNA detection methods have revealed that specific tRNAs can become modulated upon DNA copy number and chromatin alterations and can also be perturbed by oncogenic signalling and transcriptional regulators in cancer cells or the tumour microenvironment. Such alterations in the levels of specific tRNAs have been shown to causally impact cancer progression, including metastasis. Moreover, sequencing methods have identified tRNA-derived small RNAs that influence various aspects of cancer progression, such as cell proliferation and invasion, and could serve as diagnostic and prognostic biomarkers or putative therapeutic targets in various cancers. Finally, there is accumulating evidence, including from genetic models, that specific tRNA synthetases - the enzymes responsible for charging tRNAs with amino acids - can either promote or suppress tumour formation. In this Review, we provide an overview of how deregulation of tRNAs influences cancer formation and progression.

The m5 C methyltransferase NSUN2 promotes codon-dependent oncogenic translation by stabilising tRNA in anaplastic thyroid cancer

BACKGROUND

Translation dysregulation plays a crucial role in tumourigenesis and cancer progression. Oncogenic translation relies on the stability and availability of tRNAs for protein synthesis, making them potential targets for cancer therapy.

METHODS

This study performed immunohistochemistry analysis to assess NSUN2 levels in thyroid cancer. Furthermore, to elucidate the impact of NSUN2 on anaplastic thyroid cancer (ATC) malignancy, phenotypic assays were conducted. Drug inhibition and time-dependent plots were employed to analyse drug resistance. Liquid chromatography-mass spectrometry and bisulphite sequencing were used to investigate the m5 C methylation of tRNA at both global and single-base levels. Puromycin intake and high-frequency codon reporter assays verified the protein translation level. By combining mRNA and ribosome profiling, a series of downstream proteins and codon usage bias were identified. The acquired data were further validated by tRNA sequencing.

RESULTS

This study observed that the tRNA m5 C methyltransferase NSUN2 was up-regulated in ATC and is associated with dedifferentiation. Furthermore, NSUN2 knockdown repressed ATC formation, proliferation, invasion and migration both in vivo and in vitro. Moreover, NSUN2 repression enhanced the sensitivity of ATC to genotoxic drugs. Mechanically, NSUN2 catalyses tRNA structure-related m5 C modification, stabilising tRNA that maintains homeostasis and rapidly transports amino acids, particularly leucine. This stable tRNA has a substantially increased efficiency necessary to support a pro-cancer translation program including c-Myc, BCL2, RAB31, JUNB and TRAF2. Additionally, the NSUN2-mediated variations in m5C levels and different tRNA Leu iso-decoder families, partially contribute to a codon-dependent translation bias. Surprisingly, targeting NSUN2 disrupted the c-Myc to NSUN2 cycle in ATC.

CONCLUSIONS

This research revealed that a pro-tumour m5C methyltransferase, dynamic tRNA stability regulation and downstream oncogenes, c-Myc, elicits a codon-dependent oncogenic translation network that enhances ATC growth and formation. Furthermore, it provides new opportunities for targeting translation reprogramming in cancer cells.

Digging out the biology properties of tRNA-derived small RNA from black hole

An unique subclass of functional non-coding RNAs generated by transfer RNA (tRNA) under stress circumstances is known as tRNA-derived small RNA (tsRNA). tsRNAs can be divided into tRNA halves and tRNA-derived fragments (tRFs) based on the different cleavage sites. Like microRNAs, tsRNAs can attach to Argonaute (AGO) proteins to target downstream mRNA in a base pairing manner, which plays a role in rRNA processing, gene silencing, protein expression and viral infection. Notably, tsRNAs can also directly bind to protein and exhibit functions in transcription, protein modification, gene expression, protein stabilization, and signaling pathways. tsRNAs can control the expression of tumor suppressor genes and participate in the initiation of cancer. It can also mediate the progression of diseases by regulating cell viability, migration ability, inflammatory factor content and autophagy ability. Precision medicine targeting tsRNAs and drug therapy of plant-derived tsRNAs are expected to be used in clinical practice. In addition, liquid biopsy technology based on tsRNAs indicates a new direction for the non-invasive diagnosis of diseases.

Serum tRF-27-FDXXE6XRK45 as a Promising Biomarker for the Clinical Diagnosis in Gastric Cancer

Objective: Gastric cancer (GC) has high morbidity and mortality due to inefficient early screening. Therefore, we are searching for more sensitive and specific diagnostic markers for GC. tRNA-derived small RNAs are novel non-coding small RNAs with good abundance and stable presence in body fluids, which may play multiple biological regulatory roles. In this study, we aimed to find a potential biomarker with high accuracy in tRNA-derived small RNAs that can help diagnose GC. Methods: tRF-27-FDXXE6XRK45 was screened as a target molecule by high-throughput sequencing in three pairs of GC tissues. RNA quantitative reverse transcription PCR was conducted to detect the expression levels of tRF-27-FDXXE6XRK45. Agarose gel electrophoresis, Sanger sequencing, cytoplasmic and nuclear RNA isolation assays, gradient dilution experiments, and room temperature and repeated freeze-thaw experiments were used to assess the detection performance of tRF-27-FDXXE6XRK45. Using the chi-square test to analyze the correlation between tRF-27-FDXXE6XRK45 expression levels and clinicopathological parameters. In addition, receiver operating characteristic curves were used to evaluate the diagnostic value of tRF-27-FDXXE6XRK45 in GC. Results: tRF-27-FDXXE6XRK45 expression levels, significantly upregulated in tissues and sera of GC patients and decreased after radical GC surgery, were correlated with the degree of differentiation, depth of tumor infiltration, TNM stage, lymph node metastasis, and nerve/vascular invasion. In comparison with current GC diagnostic markers, tRF-27-FDXXE6XRK45 displayed better efficacy. Conclusions: tRF-27-FDXXE6XRK45, with high diagnostic efficacy, can distinguish GC patients from gastritis patients and healthy donors, suggesting that tRF-27-FDXXE6XRK45 may be a promising candidate as a diagnostic marker for GC.

Role of tRNA-derived small RNAs(tsRNAs) in the diagnosis and treatment of malignant tumours

Malignant tumours area leading cause of death globally, accounting for approximately 13% of all deaths. A detailed understanding of the mechanism(s) of the occurrence and development of malignant tumours and identification of relevant therapeutic targets are therefore key to tumour treatment. tsRNAs(tRNA-derived small RNAs)-also known as TRFs (tRNA-derived fragments), tiRNAs (tRNA-derived stress-induced RNAs), tRNA halves, etc.-are a recently identified class of small noncoding RNAs that are generated from mature tRNA or tRNA precursors through cleavage by enzymes such as angiogenin, Dicer, RNase Z, and RNase P. Several studies have confirmed that dysregulation of tsRNAs is closely related to the tumorigenesis of breast cancer, nasopharyngeal cancer, lung cancer, and so on. Furthermore, research indicates that tsRNAs can be used as clinical diagnostic markers and therapeutic targets for cancer. In our review, we summarized the recent research progress on the role and clinical application of tsRNAs in tumorigenesis and progression. Video Abstract.

Emerging roles of tRNA-derived small RNAs in cancer biology

Transfer RNAs (tRNAs) play an essential role in mRNA translation by delivering amino acids to growing polypeptide chains. Recent data demonstrate that tRNAs can be cleaved by ribonucleases, and the resultant cleavage products, tRNA-derived small RNAs (tsRNAs), have crucial roles in physiological and pathological conditions. They are classified into more than six types according to their size and cleavage positions. Since the initial discovery of the physiological functions of tsRNAs more than a decade ago, accumulating data have demonstrated that tsRNAs play critical roles in gene regulation and tumorigenesis. These tRNA-derived molecules have various regulatory functions at the transcriptional, post-transcriptional, and translational levels. More than a hundred types of modifications are found on tRNAs, affecting the biogenesis, stability, function, and biochemical properties of tsRNA. Both oncogenic and tumor suppressor functions have been reported for tsRNAs, which play important roles in the development and progression of various cancers. Abnormal expression patterns and modification of tsRNAs are associated with various diseases, including cancer and neurological disorders. In this review, we will describe the biogenesis, versatile gene regulation mechanisms, and modification-mediated regulation mechanisms of tsRNA as well as the expression patterns and potential therapeutic roles of tsRNAs in various cancers.

5’tiRNA-Pro-TGG, a novel tRNA halve, promotes oncogenesis in sessile serrated lesions and serrated pathway of colorectal cancer

BACKGROUND

Transfer RNA (tRNA)-derived small RNAs (tsRNAs) are small fragments that form when tRNAs severe. tRNA halves (tiRNAs), a subcategory of tsRNA, are involved in the oncogenic processes of many tumors. However, their specific role in sessile serrated lesions (SSLs), a precancerous lesion often observed in the colon, has not yet been elucidated.

AIM

To identify SSL-related tiRNAs and their potential role in the development of SSLs and serrated pathway of colorectal cancer (CRC).

METHODS

Small-RNA sequencing was conducted in paired SSLs and their adjacent normal control (NC) tissues. The expression levels of five SSL-related tiRNAs were validated by q-polymerase chain reaction. Cell counting kit-8 and wound healing assays were performed to detect cell proliferation and migration. The target genes and sites of tiRNA-1:33-Pro-TGG-1 (5′tiRNA-Pro-TGG) were predicted by TargetScan and miRanda algorithms. Metabolism-associated and immune-related pathways were analyzed by single-sample gene set enrichment analysis. Functional analyses were performed to establish the roles of 5′tiRNA-Pro-TGG based on the target genes.

RESULTS

In total, we found 52 upregulated tsRNAs and 28 downregulated tsRNAs in SSLs compared to NC. The expression levels of tiRNA-1:33-Gly-CCC-2, tiRNA-1:33-Pro-TGG-1, and tiRNA-1:34-Thr-TGT-4-M2 5′tiRNAs were higher in SSLs than those in NC, while that of 5′tiRNA-Pro-TGG was associated with the size of SSLs. It was demonstrated that 5′tiRNA-Pro-TGG promoted cell proliferation and migration of RKO cell in vitro. Then, heparanase 2 (HPSE2) was identified as a potential target gene of 5′tiRNA-Pro-TGG. Its lower expression was associated with a worse prognosis in CRC. Further, lower expression of HPSE2 was observed in SSLs compared to normal controls or conventional adenomas and in BRAF-mutant CRC compared to BRAF-wild CRC. Bioinformatics analyses revealed that its low expression was associated with a low interferon γ response and also with many metabolic pathways such as riboflavin, retinol, and cytochrome p450 drug metabolism pathways.

CONCLUSION

tiRNAs may profoundly impact the development of SSLs. 5′tiRNA-Pro-TGG potentially promotes the progression of serrated pathway CRC through metabolic and immune pathways by interacting with HPSE2 and regulating its expression in SSLs and BRAF-mutant CRC. In the future, it may be possible to use tiRNAs as novel biomarkers for early diagnosis of SSLs and as potential therapeutic targets in serrated pathway of CRC.

5'-tiRNA-Gln inhibits hepatocellular carcinoma progression by repressing translation through the interaction with eukaryotic initiation factor 4A-I

tRNA-derived small RNAs (tsRNAs) are novel non-coding RNAs that are involved in the occurrence and progression of diverse diseases. However, their exact presence and function in hepatocellular carcinoma (HCC) remain unclear. Here, differentially expressed tsRNAs in HCC were profiled. A novel tsRNA, tRNAGln-TTG derived 5'-tiRNA-Gln, is significantly downregulated, and its expression level is correlated with progression in patients. In HCC cells, 5'-tiRNA-Gln overexpression impaired the proliferation, migration, and invasion in vitro and in vivo, while 5'-tiRNA-Gln knockdown yielded opposite results. 5'-tiRNA-Gln exerted its function by binding eukaryotic initiation factor 4A-I (EIF4A1), which unwinds complex RNA secondary structures during translation initiation, causing the partial inhibition of translation. The suppressed downregulated proteins include ARAF, MEK1/2 and STAT3, causing the impaired signaling pathway related to HCC progression. Furthermore, based on the construction of a mutant 5'-tiRNA-Gln, the sequence of forming intramolecular G-quadruplex structure is crucial for 5'-tiRNA-Gln to strongly bind EIF4A1 and repress translation. Clinically, 5'-tiRNA-Gln expression level is negatively correlated with ARAF, MEK1/2, and STAT3 in HCC tissues. Collectively, these findings reveal that 5'-tiRJNA-Gln interacts with EIF4A1 to reduce related mRNA binding through the intramolecular G-quadruplex structure, and this process partially inhibits translation and HCC progression.

Role of ADAM33 short isoform as a tumor suppressor in the pathogenesis of thyroid cancer via oncogenic function disruption of full-length ADAM33

Thyroid cancer is the most prevalent endocrine malignancy globally; however, its underlying pathogenesis remains unclarified. Reportedly, alternative splicing is involved in processes such as embryonic stem and precursor cell differentiation, cell lineage reprogramming, and epithelial-mesenchymal transitions. ADAM33-n, an alternative splicing isoform of ADAM33, encodes a small protein containing 138 amino acids of the N-terminal of full-length ADAM33, which constructs a chaperone-like domain that was previously reported to bind and block the proteolysis activity of ADAM33. In this study, we reported for the first time that ADAM33-n was downregulated in thyroid cancer. The results of cell counting kit-8 and colony formation assays showed that ectopic ADAM33-n in papillary thyroid cancer cell lines restricted cell proliferation and colony formation. Moreover, we demonstrated that ectopic ADAM33-n reversed the oncogenic function of full-length ADAM33 in cell growth and colony formation in the MDA-T32 and BCPAP cells. These findings indicate the tumor suppressor ability of ADAM33-n. Altogether, our study findings present a potential explanatory model of how the downregulation of the oncogenic gene ADAM33 promotes the pathogenesis of thyroid cancer.

Identification of RNA helicases with unwinding activity on angiogenin-processed tRNAs

Stress-induced tRNA fragmentation upon environmental insult is a conserved cellular process catalysed by endonucleolytic activities targeting mature tRNAs. The resulting tRNA-derived small RNAs (tsRNAs) have been implicated in various biological processes that impact cell-to-cell signalling, cell survival as well as gene expression regulation during embryonic development. However, how endonuclease-targeted tRNAs give rise to individual and potentially biologically active tsRNAs remains poorly understood. Here, we report on the in vivo identification of proteins associated with stress-induced tsRNAs-containing protein complexes, which, together with a 'tracer tRNA' assay, were used to uncover enzymatic activities that can bind and process specific endonuclease-targeted tRNAs in vitro. Among those, we identified conserved ATP-dependent RNA helicases which can robustly separate tRNAs with endonuclease-mediated 'nicks' in their anticodon loops. These findings shed light on the existence of cellular pathways dedicated to producing individual tsRNAs after stress-induced tRNA hydrolysis, which adds to our understanding as to how tRNA fragmentation and the resulting tsRNAs might exert physiological impact.

Emerging roles of tRNA-derived fragments in cancer

tRNA-derived fragments (tRFs) are an emerging category of small non-coding RNAs that are generated from cleavage of mature tRNAs or tRNA precursors. The advance in high-throughput sequencing has contributed to the identification of increasing number of tRFs with critical functions in distinct physiological and pathophysiological processes. tRFs can regulate cell viability, differentiation, and homeostasis through multiple mechanisms and are thus considered as critical regulators of human diseases including cancer. In addition, increasing evidence suggest the extracellular tRFs may be utilized as promising diagnostic and prognostic biomarkers for cancer liquid biopsy. In this review, we focus on the biogenesis, classification and modification of tRFs, and summarize the multifaceted functions of tRFs with an emphasis on the current research status and perspectives of tRFs in cancer.

Inhibition of tiRNA-Gly-GCC ameliorates neointimal formation via CBX3-mediated VSMCs phenotypic switching

Background and aim

tRNA-derived fragments (tRFs) are a new class of non-coding RNAs involved in a variety of pathological processes, but their biological functions and mechanisms in human aortic smooth muscle cells (HASMCs) phenotype transition and vascular intimal hyperplasia are unclear.

Methods/results

tiRNA-Gly-GCC is upregulated in synthetic HASMCs, atherosclerotic arteries, plasma, and the balloon injured carotid artery of rats. Functionally, the inhibition of tiRNA-Gly-GCC represses HASMCs proliferation, migration, and reversed dedifferentiation, whereas the overexpression of tiRNA- Gly-GCC have contrary effects. Mechanistically, tiRNA-Gly-GCC performs these functions on HASMCs via downregulating chromobox protein homolog 3 (CBX3). Finally, the inhibition of tiRNA-Gly-GCC could ameliorate neointimal formation after vascular injury in vivo.

Conclusions

tiRNA-Gly-GCC is a mediator of HASMCs phenotypic switching by targeting CBX3 and inhibition of tiRNA-Gly-GCC suppresses neointimal formation.

5'-tRF-GlyGCC promotes breast cancer metastasis by increasing fat mass and obesity-associated protein demethylase activity

tRNA-derived fragments (tRFs) are a class of regulatory non-coding RNAs that play essential biological functions in cancer and stress-induced diseases. Several lines of evidence suggest that 5'-tRF-GlyGCC participates in tumor progression; however, its molecular mechanisms remain unclear. In this study, we explored the function of 5'-tRF-GlyGCC in breast cancer (BC) progression and studied the related potential molecular mechanisms. 5'-tRF-GlyGCC expression increased in human BC, and it promoted the proliferation, migration, and invasion of BC cells in vitro and tumor growth and metastasis in vivo. 5'-tRF-GlyGCC was found for the first time to bind directly to fat mass and obesity-associated proteins, and increase the activity of FTO demethylase, reducing eIF4G1 methylation, inhibiting autophagy, and promoting BC proliferation and metastasis. These findings suggest that 5'-tRF-GlyGCC might be a therapeutic target for treating BC.

tRNA derived fragments:A novel player in gene regulation and applications in cancer

The heterogeneous species of tRNA-derived fragments (tRFs) with specific biological functions was recently identified. Distinct roles of tRFs in tumor development and viral infection, mediated through transcriptional and post-transcriptional regulation, has been demonstrated. In this review, we briefly summarize the current literatures on the classification of tRFs and the effects of tRNA modification on tRF biogenesis. Moreover, we highlight the tRF repertoire of biological roles such as gene silencing, and regulation of translation, cell apoptosis, and epigenetics. We also summarize the biological roles of various tRFs in cancer development and viral infection, their potential value as diagnostic and prognostic biomarkers for different types of cancers, and their potential use in cancer therapy.

Downregulation of RBM17 enhances cisplatin sensitivity and inhibits cell invasion in human hypopharyngeal cancer cells

Most of advanced hypopharyngeal squamous cell carcinoma (HSCC) are resistant to chemotherapy, and there is still lack of effective treatment for HSCC now. The present study aimed to investigate whether downregulation of RNA-binding motif protein 17 (RBM17) could enhance cisplatin sensitivity and inhibit cell invasion in HSCC and the underlying mechanism. We observed that RBM17 was upregulated in tumor tissues and associated with poor progression. Treatment of FaDu cells with cisplatin increased RBM17 expression in mRNA levels. Downregulation of RBM17 enhanced cisplatin-mediated inhibition of FaDu cells. In addition, downregulation of RBM17 effectively suppressed tumor cell migration and invasion through the reversion of epithelial-mesenchymal transition. Moreover, downregulation of RBM17 could significantly slow tumor growth in FaDu xenograft tumor model. Liquid chromatography-mass spectrometry/mass spectrometry detection and independent PRM analysis showed that 21 differentially expressed proteins were associated with the downregulation of RBM17. Taken together, our study implied that downregulation of RBM17 could serve as a novel approach to enhance cisplatin sensitivity in HSCC.

N6-Methyladenosine-modified lncRNA LINREP promotes Glioblastoma progression by recruiting the PTBP1/HuR complex

Glioblastoma multiforme (GBM) is acknowledged as the most aggressive primary brain tumor in adults. It is typically characterized by the high heterogeneity which corresponds to extensive genetic mutations and complex alternative splicing (AS) profiles. Known as a major repressive splicing factor in AS, polypyrimidine tract-binding protein 1 (PTBP1) is involved in the exon skipping events of multiple precursor mRNAs (pre-mRNAs) in GBM. However, precise mechanisms that modulate the expression and activity of PTBP1 remain to be elucidated. In present study, we provided evidences for the role of a long intergenic noncoding RNA (LINREP) implicated in the regulation of PTBP1-induced AS. LINREP interacted with PTBP1 and human antigen R (HuR, ELAVL1) protein complex and protected PTBP1 from the ubiquitin-proteasome degradation. Consequently, a broad spectrum of PTBP1-induced spliced variants was generated by exon skipping, especially for the skipping of reticulon 4 (RTN4) exon 3. Interestingly, LINREP also promoted the dissociation of nuclear UPF1 from PTBP1, which increased the binding of PTBP1 to RTN4 transcripts, thus enhancing the skipping of RTN4 exon 3 to some extent. Besides, HuR recruitment was essential for the stabilization of LINREP via a manner dependent on N6-methyladenosine (m6A) formation and identification. Taken together, our results demonstrated the functional significance of LINREP in human GBM for its dual regulation of PTBP1-induced AS and its m6A modification modality, implicating that HuR/LINREP/PTBP1 axis might serve as a potential therapeutic target for GBM.

Transfer RNA-derived fragment 5'tRF-Gly promotes the development of hepatocellular carcinoma by direct targeting of carcinoembryonic antigen-related cell adhesion molecule 1

Transfer RNA-derived fragments are a group of small noncoding single-stranded RNA that play essential roles in multiple diseases. However, their biological functions in carcinogenesis are not well understood. In this study, 5'tRF-Gly was found to have significantly high expression in hepatocellular carcinoma (HCC), and the upregulation of 5'tRF-Gly was positively correlated with tumor size and tumor metastasis. Overexpression of 5'tRF-Gly induced increased growth rate and metastasis in HCC cells in vitro and in nude mice, while knockdown showed the opposite effect. Carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1) was confirmed to be a direct target of 5'tRF-Gly in HCC. In addition, the cytological effect of CEACAM1 knockdown proved to be similar to the overexpression of 5'tRF-Gly. Moreover, attenuation of CEACAM1 expression rescued the 5'tRF-Gly-mediated promoting effects on HCC cells. These data show that 5'tRF-Gly is a new tumor-promoting factor and could be a potential diagnostic biomarker or new therapeutic target for HCC.

tRNA derived small RNAs—Small players with big roles

In the past 2 decades, small non-coding RNAs derived from tRNA (tsRNAs or tRNA derived fragments; tRFs) have emerged as new powerful players in the field of small RNA mediated regulation of gene expression, translation, and epigenetic control. tRFs have been identified from evolutionarily divergent organisms from Archaea, the higher plants, to humans. Recent studies have confirmed their roles in cancers and other metabolic disorders in humans and experimental models. They have been implicated in biotic and abiotic stress responses in plants as well. In this review, we summarize the current knowledge on tRFs including types of tRFs, their biogenesis, and mechanisms of action. The review also highlights recent studies involving differential expression profiling of tRFs and elucidation of specific functions of individual tRFs from various species. We also discuss potential considerations while designing experiments involving tRFs identification and characterization and list the available bioinformatics tools for this purpose.

Characteristics of tRNA-Derived Small RNAs and microRNAs Associated with Immunocompromise in an Intrauterine Growth-Restricted Pig Model

Simple Summary

Intrauterine growth restriction (IUGR) refers to the slow growth and development of an embryo or fetus in the uterus of mammals. IUGR newborns commonly present with slow growth and the development of the body and organs accompany increased risks of infection during the early life period. IUGR remains a significant global public health issue, particularly in developing countries. In this work, we investigated the transfer RNA-derived small RNA and microRNA expression profiles in the spleen using pigs as an IUGR model. These results uncover an important potential regulator network involved in immunocompromise caused by IUGR. The present studies provide a novel perspective on the molecular regulatory mechanism of IUGR and a reference for prevention and treatment.

Abstract

Intrauterine growth restriction (IUGR) is an important cause of newborn morbidity and mortality in mammals. Transfer RNA-derived small RNA (tsRNA) has become an emerging non-coding RNA in recent years. tsRNA and microRNAs (miRNAs) share similar mechanisms, which are involved in various biological processes. In this study, the pig was used as a model of IUGR, and the tsRNA and miRNA expression profile in the spleen was characterized by RNA sequencing. A total of 361 miRNAs and 620 tsRNAs were identified, of which 22 were differentially expressed miRNA (DEM) and 25 differentially expressed tsRNA (DET). tRF-5c were the primary tsRNA type making up more than 90%, and the most abundantly expressed tsRNAs are from tRNA-Gly-GCC. Functional enrichment analysis found that those DETs and DEMs have been implicated in the immune system process. Protein–protein interaction (PPI) network analysis revealed ssc-miR-370, ssc-miR-206, tiRNA-Ser-TGA-001 and tRF-Val-AAC-034 could be major regulators. TNF, TLR4, CD44, MAPK1 and STAT1 were predicted hub target genes. Those DETs and DEMs may regulate the T-cell receptor signaling pathway and Toll-like receptor signaling pathway to mediate the immunocompromise caused by IUGR. The results discussed in this article uncover the potential role of tsRNAs and miRNAs in IUGR porcine spleen.

Genome-wide repertoire of transfer RNA-derived fragments in a mouse model of age-related cataract

Purpose To investigate the roles of tRNA-derived small RNAs (tsRNAs) containing transfer RNA-derived fragments (tRFs) and tRNA halves in age-related cataract (ARC). Methods: Lens capsule tissue from Emory mice at 3 months and 8 months of age were dissected for integrated tsRNA and gene transcriptome sequencing. Quantitative real-time PCR assay (qRT-PCR) was perform for validating sequencing results. Bioinformatics analysis was constructed to reveal the roles of tsRNAs. Results: A total of 422 DE tsRNAs were changed, in which 156 were elevated while 266 were declined in 8-month-old mice. Subsequently, the gene sequencing data exhibited 375 upregulated and 456 downregulated DE genes. Validation by qRT-PCR in 5 selected upregulated tRFs was consistent with tsRNAs sequencing results. Moreover, bioinformatics analysis identified 25 downregulated target genes of the 5 validated tRFs. Furthermore, GO analysis revealed that these target genes were mainly enriched in camera-type eye development, sensory organ development and so on. Conclusion: Our study provide a novel perspective for the role of tsRNAs in pathogenesis of ARC, and thus therapeutic potential targets for ARC.

Transfer RNA-derived small RNA: an emerging small non-coding RNA with key roles in cancer

Transfer RNAs (tRNAs) promote protein translation by binding to the corresponding amino acids and transporting them to the ribosome, which is essential in protein translation. tRNA-derived small RNAs (tsRNAs) are derived fragments of tRNAs that are cleaved explicitly under certain conditions. An increasing amount of research has demonstrated that tsRNAs have biological functions rather than just being degradation products. tsRNAs can exert functions such as regulating gene expression to influence cancer progression. Their dysregulation is closely associated with various cancers and can serve as diagnostic and prognostic biomarkers for cancer. This review summarizes the generation, classification, and biological functions of tsRNAs, and highlights the roles of tsRNAs in different cancers and their applications as tumor markers.

A novel 3'tRNA-derived fragment tRF-Val promotes proliferation and inhibits apoptosis by targeting EEF1A1 in gastric cancer

At present, it is commonly believed that tRFs and tiRNAs are formed by the specific and selective shear of tRNAs under certain pressure stimulation, rather than by random degradation of tRNA. tRFs and tiRNAs have been reported to contribute to the biological process of a variety of human cancers. However, the evidence for the mechanisms of tRFs and tiRNAs in the occurrence and development of gastric cancer (GC) is still insufficient. Here, we aimed to explore the carcinogenic roles of tRFs and tiRNAs in GC with RNA-sequencing technique, and found a novel 3'tRNA-derived fragment tRF-Val was significantly upregulated in GC tissues and cell lines. tRF-Val expression was positively correlated with tumor size and the depth of tumor invasion in GC tissues. Functionally, tRF-Val promoted proliferation and invasion, and inhibited apoptosis in GC cells. Mechanistically, tRF-Val directly bound to the chaperone molecule EEF1A1, mediated its transport into the nucleus and promoted its interaction with MDM2 (a specific p53 E3 ubiquitin ligase), thus inhibiting the downstream molecular pathway of p53 and promoting GC progression. These findings provided a new potential therapeutic target for GC and a new explanation for the occurrence of GC.

The tRNA-Derived Fragment tRF-24-V29K9UV3IU Functions as a miRNA-like RNA to Prevent Gastric Cancer Progression by Inhibiting GPR78 Expression

Emerging studies have proved that tRNA-derived fragments (tRFs) play vital roles in tumor metastasis; however, the function of tRFs in gastric cancer (GC) remains largely unclear. We investigated the role of tRF-24-V29K9UV3IU in growth and metastasis of GC using a xenograft mouse model. Differential gene expression downstream of tRF-24-V29K9UV3IU was identified by transcriptome sequencing, and interaction was then verified by a dual luciferase reporter and RNA immunoprecipitation. MKN-45 cells were also used to explore the biological functions of tRF-24-V29K9UV3IU in vitro. Here, knockdown of tRF-24-V29K9UV3IU promoted tumor growth and metastasis of GC in vivo. The expression of tRF-24-V29K9UV3IU and E-cadherin (epithelial cell marker) was down-regulated in tumors of mice following tRF-24-V29K9UV3IU knockdown, whereas the mesenchymal cell markers N-cadherin and vimentin displayed an opposite trend. Transcriptome sequencing identified 87 differentially expressed genes (DEGs) down-regulated in the tRF-24-V29K9UV3IU-overexpressed groups compared with the control group. Among them, G-protein–coupled receptor 78 (GPR78), the most significantly down-regulated DEG, was also predicted to be a target of tRF-24-V29K9UV3IU. Moreover, tRF-24-V29K9UV3IU could function as a miRNA-like fragment and bind to AGO2 and directly silence GPR78 expression by complementing with the 3′-untranslated region of the GPR78 mRNA. Functionally, overexpression of tRF-24-V29K9UV3IU significantly suppressed proliferation, migration, and invasion and promoted apoptosis of MKN-45 cells, whereas GPR78 attenuated these effects. Therefore, our data suggest that tRF-24-V29K9UV3IU functions as a miRNA-like fragment to suppress GPR78 expression and thus inhibit GC progression. These observations suggest that the tRF-24-V29K9UV3IU/GPR78 axis serves as a potential therapeutic target in GC.

An emerging role of the 5' termini of mature tRNAs in human diseases: Current situation and prospects

The fundamental biological roles of a class of small noncoding RNAs (sncRNAs), derived from mature tRNAs or pre-tRNAs, in human diseases have received increasing attention in recent years. These ncRNAs are called tRNA-derived fragments (tRFs) or tRNA-derived small RNAs (tsRNAs). tRFs mainly include tRF-1, tRF-5, tRF-3 and tRNA halves (tiRNAs or tRHs), which are produced by enzyme-specific cleavage of tRNAs. Here, we classify tRF-5 and 5' tiRNAs into the same category: 5'-tRFs and review the biological functions and regulatory mechanisms of 5'-tRFs in cancer and other diseases (metabolic diseases, neurodegenerative diseases, pathological stress injury and virus infection) to provide a new theoretical basis for the diagnosis and treatment of diseases.

Alternative Splicing, Epigenetic Modifications and Cancer: A Dangerous Triangle, or a Hopeful One?

Simple Summary

Epigenetics studies the alteration of gene expression without changing DNA sequence and very often, epigenetic dysregulation causes cancer. Alternative splicing is a mechanism that results in the production of several mRNA isoforms from a single gene and aberrant splicing is also a frequent cause of cancer. The present review is built on the interrelations of epigenetics and alternative splicing. In an intuitive way, we say that epigenetic modifications and alternative splicing are at two vertices of a triangle, the third vertex being occupied by cancer. Interconnection between alternative splicing and epigenetic modifications occurs backward and forward and the mechanisms involved are widely reviewed. These connections also provide novel diagnostic or prognostic tools, which are listed. Finally, as epigenetic alterations are reversible and aberrant alternative splicing may be corrected, the therapeutic possibilities to break the triangle are discussed.

Abstract

The alteration of epigenetic modifications often causes cancer onset and development. In a similar way, aberrant alternative splicing may result in oncogenic products. These issues have often been individually reviewed, but there is a growing body of evidence for the interconnection of both causes of cancer. Actually, aberrant splicing may result from abnormal epigenetic signalization and epigenetic factors may be altered by alternative splicing. In this way, the interrelation between epigenetic marks and alternative splicing form the base of a triangle, while cancer may be placed at the vertex. The present review centers on the interconnections at the triangle base, i.e., between alternative splicing and epigenetic modifications, which may result in neoplastic transformations. The effects of different epigenetic factors, including DNA and histone modifications, the binding of non-coding RNAs and the alterations of chromatin organization on alternative splicing resulting in cancer are first considered. Other less-frequently considered questions, such as the epigenetic regulation of the splicing machinery, the aberrant splicing of epigenetic writers, readers and erasers, etc., are next reviewed in their connection with cancer. The knowledge of the above-mentioned relationships has allowed increasing the collection of biomarkers potentially useful as cancer diagnostic and/or prognostic tools. Finally, taking into account on one hand that epigenetic changes are reversible, and some epigenetic drugs already exist and, on the other hand, that drugs intended for reversing aberrations in alternative splicing, therapeutic possibilities for breaking the mentioned cancer-related triangle are discussed.

tRNA Metabolism and Lung Cancer: Beyond Translation

Lung cancer, one of the most malignant tumors, has extremely high morbidity and mortality, posing a serious threat to global health. It is an urgent need to fully understand the pathogenesis of lung cancer and provide new ideas for its treatment. Interestingly, accumulating evidence has identified that transfer RNAs (tRNAs) and tRNA metabolism–associated enzymes not only participate in the protein translation but also play an important role in the occurrence and development of lung cancer. In this review, we summarize the different aspects of tRNA metabolism in lung cancer, such as tRNA transcription and mutation, tRNA molecules and derivatives, tRNA-modifying enzymes, and aminoacyl-tRNA synthetases (ARSs), aiming at a better understanding of the pathogenesis of lung cancer and providing new therapeutic strategies for it.