LncRNA HOTAIR-mediated MTHFR methylation inhibits 5-fluorouracil sensitivity in esophageal cancer cells

Deciphering the mechanisms of long non-coding RNAs in ferroptosis: insights into its clinical significance in cancer progression and immunology

A new type of nonapoptotic, iron-dependent cell death induced by lipid peroxidation is known as ferroptosis. Numerous pathological processes, including inflammation and cancer, have been demonstrated to be influenced by changes in the ferroptosis-regulating network. Long non-coding RNAs (LncRNAs) are a group of functional RNA molecules that are not translated into proteins, which can regulate gene expression in various manners. An increasing number of studies have shown that lncRNAs can interfere with the progression of ferroptosis by modulating ferroptosis-related genes directly or indirectly. Despite evidence implicating lncRNAs in cancer and inflammation, studies on their mechanisms and therapeutic potential remain scarce. We investigate the mechanisms of lncRNA-mediated regulation of inflammation and cancer immunity, assessing the feasibility and challenges of lncRNAs as therapeutic targets in these conditions.

HOTAIR in cancer: diagnostic, prognostic, and therapeutic perspectives

The long non-coding RNA HOTAIR is overexpressed in many cancers and is associated with several cancer-promoting effects, including increased cell proliferation, migration and treatment resistance. HOTAIR levels correlate with tumor stage, lymph node metastasis and overall survival in patients with various types of cancer. This highlights the potential uses of HOTAIR, including early cancer detection, predicting patient outcome, identifying high-risk individuals and assisting in therapy selection and monitoring. The aim of this review is to provide a comprehensive summary of the research progress, molecular mechanisms and clinical significance of HOTAIR in various human cancers. In addition, the clinical applications of HOTAIR, such as targeted therapy, radiotherapy, chemotherapy and immunotherapy, are discussed, and relevant information on the potential future advances of HOTAIR in cancer research is provided.

LncRNAs and the cancer epigenome: Mechanisms and therapeutic potential

Long non-coding RNAs (lncRNAs) have emerged as critical regulators of epigenome, modulating gene expression through DNA methylation, histone modification, and/or chromosome remodeling. Dysregulated lncRNAs act as oncogenes or tumor suppressors, driving tumor progression by shaping the cancer epigenome. By interacting with the writers, readers, and erasers of the epigenetic script, lncRNAs induce epigenetic modifications that bring about changes in cancer cell proliferation, apoptosis, epithelial-mesenchymal transition, migration, invasion, metastasis, cancer stemness and chemoresistance. This review analyzes and discusses the multifaceted role of lncRNAs in cancer pathobiology, from cancer genesis and progression through metastasis and therapy resistance. It also explores the therapeutic potential of targeting lncRNAs through innovative diagnostic, prognostic, and therapeutic strategies. Understanding the dynamic interplay between lncRNAs and epigenome is crucial for developing personalized therapeutic strategies, offering new avenues for precision cancer medicine.

lncRNAs: New players of cancer drug resistance via targeting ABC transporters

Cancer drug resistance poses a significant obstacle to successful chemotherapy, primarily driven by the activity of ATP-binding cassette (ABC) transporters, which actively efflux chemotherapeutic agents from cancer cells, reducing their intracellular concentrations and therapeutic efficacy. Recent studies have highlighted the pivotal role of long noncoding RNAs (lncRNAs) in regulating this resistance, positioning them as crucial modulators of ABC transporter function. lncRNAs, once considered transcriptional noise, are now recognized for their complex regulatory capabilities at various cellular levels, including chromatin modification, transcription, and post-transcriptional processing. This review synthesizes current research demonstrating how lncRNAs influence cancer drug resistance by modulating the expression and activity of ABC transporters. lncRNAs can act as molecular sponges, sequestering microRNAs that would otherwise downregulate ABC transporter genes. Additionally, they can alter the epigenetic landscape of these genes, affecting their transcriptional activity. Mechanistic insights reveal that lncRNAs contribute to the activity of ABC transporters, thereby altering the efflux of chemotherapeutic drugs and promoting drug resistance. Understanding these interactions provides a new perspective on the molecular basis of chemoresistance, emphasizing the regulatory network of lncRNAs and ABC transporters. This knowledge not only deepens our understanding of the biological mechanisms underlying drug resistance but also suggests novel therapeutic strategies. In conclusion, the intricate interplay between lncRNAs and ABC transporters is crucial for developing innovative solutions to combat cancer drug resistance, underscoring the importance of continued research in this field.

Long noncoding RNA KCNMA1-AS2 regulates the function of colorectal cancer cells and sponges miR-1227-5p

BACKGROUND

Many long noncoding RNAs (lncRNAs) with altered expression significantly influence colorectal cancer (CRC) progression and behavior. The functions of many lncRNAs in CRC are not clear yet. This study aimed to discover novel lncRNA entities and comprehensively examine and validate their roles and underlying molecular mechanisms in CRC.

METHODS

Tissue samples, both tumourous and non-tumourous, from three CRC patients were submitted for sequencing. Following expression validation in samples from ten patients and four CRC cell lines. The lncRNA KCNMA1-AS2 was synthesized by In-vitro transcription RNA synthesis and the lncRNA was directly transfected into CRC cell lines to overexpress. Functional assays including MTT proliferation assay, Annexin-V/propidium iodide apoptosis assay, wound healing migration assay and cell cycle assays were performed to evaluate the effect of overexpression of KCNMA1-AS2. Furthermore, the binding of KCNMA1-AS2 to miR-1227-5p was confirmed using dual luciferase reporter assays and qPCR analyses. Subsequent bioinformatics analyses identified 58 potential downstream targets of miR-1227-5p across three databases.

RESULTS

In this study, we identified the lncRNA KCNMA1-AS2, the expression of which was down-regulated consistently in cancer tissues and CRC cell lines compared to non-cancerous tissues. The overexpression of lncRNA KCNMA1-AS2 led to significant reduction in CRC cell proliferation and migration, increase in cell apoptosis, and more cells arrested in S phase. Additionally, the interaction between KCNMA1-AS2 and miR-1227-5p was confirmed through dual luciferase reporter assay and qPCR analysis. It is also putatively predicted that MTHFR and ST8SIA2 may be linked to CRC based on bioinformatics analyses.

CONCLUSIONS

LncRNA KCNMA1-AS2 exhibited distinct gene expression patterns in both CRC tissue and cell lines, impacting various cellular functions while also acting as a sponge for miR-1227-5p.The findings spotlight lncRNA KCNMA1-AS2 as a potential marker for diagnosis and treatment of CRC.

LncRNAs: the art of being influential without protein

The plant long noncoding (lnc)RNA field is on the brink of transitioning from large-scale identification of lncRNAs to their functional characterization. Due to the cross-kingdom conservation of interaction types and molecular functions, there is much to be learned from mammalian lncRNA research. Here, we discuss the different molecular processes involving lncRNAs from the regulation of chromatin to splicing. Furthermore, we discuss the lncRNA interactome, which includes proteins, other RNAs, and DNA. We explore and discuss how mammalian lncRNA functionalities could be reflected in similar pathways in plants and hypothesize that several breakthroughs in mammalian research could lead to the discovery of novel plant lncRNA molecular functions. Expanding our knowledge of the biological role of lncRNAs and their multiple applications paves the way for future agricultural applications.

Long non-coding RNA HOTAIR: from pan-cancer analysis to colorectal cancer-related uridine metabolism

Long non-coding RNAs (lncRNAs) are involved significantly in the development of human cancers. lncRNA HOTAIR has been reported to play an oncogenic role in many human cancers. Its specific regulatory role is still elusive. And it might have enormous potential to interpret the malignant progression of tumors in a broader perspective, that is, in pan-cancer. We comprehensively investigated the effect of HOTAIR expression on tumor prognosis across human malignancies by analyzing multiple cancer-related databases like The Cancer Genome Atlas (TCGA) and Tumor Immune Estimation Resource (TIMER). Bioinformatics data indicated that HOTAIR was overexpressed in most of these human malignancies and was significantly associated with the prognosis of patients with cancer, especially in colorectal cancer (CRC). Subsequently, this study further clarified the utility of HOTAIR that downregulation of its expression could result in reduced proliferation and invasion of CRC cells. Mechanistically, HOTAIR upregulated the metabolic enzymes UPP1 by recruiting histone methyltransferase EZH2, thereby increasing the tumor progression. Our results highlight the essential role of HOTAIR in pan-cancer and uridine bypass, suggesting that the HOTAIR/EZH2/UPP1 axis might be a novel target for overcoming CRC. We anticipate that the role of HOTAIR in metabolism could be important in the context of CRC and even exploited for therapeutic purposes.

Associations of long non-coding RNAs HOTAIR, LINC00951, POLR2E and HULC polymorphisms with the risk of esophageal and esophagogastric junction cancer in a western population: a case-control study

BACKGROUND

The incidence of single-nucleotide-polymorphisms with malignant potential in esophageal cancer tissues has only been sparsely investigated in the west. Hence, we explored the contribution of four long non-coding RNAs' polymorphisms HOTAIR rs920778, LINC00951 rs11752942, POLR2E rs3787016 and HULC rs7763881 in esophageal cancer susceptibility.

METHODS AND RESULTS

Formalin-fixed paraffin-embedded tissue specimens from 95 consecutive patients operated for esophageal/esophagogastric junction carcinoma during 25/03/2014-25/09/2018 were processed. Demographic data, histopathological parameters, surgical and oncological outcomes were collected. DNA findings of the abovementioned population were compared with 121 healthy community controls. Both populations were of European/Greek ancestry. Sixty-seven patients underwent Ivor Lewis/McKeown esophagectomy for either squamous cell esophageal carcinoma (N = 6) or esophageal/esophagogastric junction Siewert I or II adenocarcinoma (N = 61). Twenty-eight patients were subjected to extended total gastrectomy for esophagogastric junction Siewert III adenocarcinoma. Neither LINC00951 rs11752942 nor HULC rs7763881 polymorphisms were detected more frequently in esophageal cancer patients compared with healthy community subjects. A significantly higher presence of HOTAIR rs920778 TT genotype in esophagogastric junction Siewert I/II adenocarcinoma was identified. POLR2E rs3787016 C allele and CC genotypes were overrepresented in the control group, and when found in esophageal cancer carriers were associated with earlier disease stages, as well as with minor lymph node involvement and lesser metastatic potential.

CONCLUSIONS

HOTAIR rs920778 may serve as a potential therapeutic suppression target, while POLR2E rs3787016 may represent a valuable biomarker to evaluate esophageal cancer predisposition and predict treatment response and prognosis. Clinical implications of these findings need to be verified with further prospective studies with larger sample-size.

CENPA knockdown restrains cell progression and tumor growth in breast cancer by reducing PLA2R1 promoter methylation and modulating PLA2R1/HHEX axis

BACKGROUND

Breast cancer is a lethal malignancy affecting females worldwide. It has been reported that upregulated centromere protein A (CENPA) expression might indicate unfortunate prognosis and can function as a prognostic biomarker in breast cancer. This study aimed to investigate the accurate roles and downstream mechanisms of CENPA in breast cancer progression.

METHODS

CENPA protein levels in breast cancer tissues and cell lines were analyzed by Western blot and immunohistochemistry assays. We used gain/loss-of-function experiments to determine the potential effects of CENPA and phospholipase A2 receptor (PLA2R1) on breast cancer cell proliferation, migration, and apoptosis. Co-IP assay was employed to validate the possible interaction between CENPA and DNA methyltransferase 1 (DNMT1), as well as PLA2R1 and hematopoietically expressed homeobox (HHEX). PLA2R1 promoter methylation was determined using methylation-specific PCR assay. The biological capabilities of CENPA/PLA2R1/HHEX axis in breast cancer cells was determined by rescue experiments. In addition, CENPA-silenced MCF-7 cells were injected into mice, followed by measurement of tumor growth.

RESULTS

CENPA level was prominently elevated in breast cancer tissues and cell lines. Interestingly, CENPA knockdown and PLA2R1 overexpression both restrained breast cancer cell proliferation and migration, and enhanced apoptosis. On the contrary, CENPA overexpression displayed the opposite results. Moreover, CENPA reduced PLA2R1 expression through promoting DNMT1-mediated PLA2R1 promoter methylation. PLA2R1 overexpression could effectively abrogate CENPA overexpression-mediated augment of breast cancer cell progression. Furthermore, PLA2R1 interacted with HHEX and promoted HHEX expression. PLA2R1 knockdown increased the rate of breast cancer cell proliferation and migration but restrained apoptosis, which was abrogated by HHEX overexpression. In addition, CENPA silencing suppressed tumor growth in vivo.

CONCLUSION

CENPA knockdown restrained breast cancer cell proliferation and migration and attenuated tumor growth in vivo through reducing PLA2R1 promoter methylation and increasing PLA2R1 and HHEX expression. We may provide a promising prognostic biomarker and novel therapeutic target for breast cancer.

Deciphering the Epigenetic Symphony of Cancer: Insights and Epigenetic Therapies Implications

Epigenetic machinery is a cornerstone in normal cell development, orchestrating tissue-specific gene expression in mammalian cells. Aberrations in this intricate landscape drive substantial changes in gene function, emerging as a linchpin in cancer etiology and progression. While cancer was conventionally perceived as solely a genetic disorder, its contemporary definition encompasses genetic alterations intertwined with disruptive epigenetic abnormalities. This review explores the profound impact of DNA methylation, histone modifications, and noncoding RNAs on fundamental cellular processes. When these pivotal epigenetic mechanisms undergo disruption, they intricately guide the acquisition of the 6 hallmark characteristics of cancer within seemingly normal cells. Leveraging the latest advancements in decoding these epigenetic intricacies holds immense promise, heralding a new era in developing targeted and more efficacious treatment modalities against cancers driven by aberrant epigenetic modifications.

Noncoding RNA as an influential epigenetic modulator with promising roles in cancer therapeutics

The epigenetic landscape has an important role in cellular homeostasis and its deregulation leads to cancer. Noncoding (nc)RNA networks function as major regulators of cellular epigenetic hallmarks via regulation of vital processes, such as histone modification and DNA methylation. They are integral intracellular components affecting multiple oncogenic pathways. Thus, it is important to elucidate the effects of ncRNA networks on epigenetic programming that lead to the initiation and progression of cancer. In this review, we summarize the effects of epigenetic modification influenced by ncRNA networks and crosstalk between diverse classes of ncRNA, which could aid the development of patient-specific cancer therapeutics targeting ncRNAs, thereby altering cellular epigenetics.

A new marker constructed from immune-related lncRNA pairs can be used to predict clinical treatment effects and prognosis: in-depth exploration of underlying mechanisms in HNSCC

BACKGROUND

Long non-coding RNA (lncRNA) plays a vital role in tumor proliferation, migration, and treatment. Since it is challenging to standardize the gene expression levels detected by different platforms, the signatures composed of many immune-related single lncRNAs are still inaccurate. Utilizing a gene pair formed of two immune-related lncRNAs and strategically assigning values can effectively meet the demand for a higher-accuracy dual biomarker combination.

METHODS

Co-expression and differential expression analyses were performed on immune genes and lncRNAs data from The Cancer Genome Atlas and the ImmPort database to obtain differentially expressed immune-related lncRNAs for pairwise pairing. The prognostic-related differentially expressed immune-related lncRNAs (PR-DE-irlncRNAs) pairs were then identified by univariate Cox regression and used for lasso regression to construct a prognostic model. Various methods were used to validate the predictive prognostic performance of the model. Additionally, we explored the potential guiding value of the model in immunotherapy and chemotherapy and constructed a nomogram suitable for efficient prognosis prediction. Mechanistic exploration of anti-tumor immunity and mutational perspectives are also included. We also analyzed the correlation between the model and immune checkpoint inhibitors (ICIs)-related, N6-methyadenosine (m6A)-related, and multidrug resistance genes.

RESULTS

We used a total of 20 pairs of PR-DE-irlncRNAs to create a prognosis model. Quantitative real-time polymerase chain reaction experiments further verified the abnormal expression of 11 lncRNAs in HNSCC cells. Various methods have confirmed the excellent performance of the model in predicting patient prognosis. We reasoned that lncRNAs/TP53 mutation might play a positive/negative anti-tumor role through the immune system by multi-perspective analyses. Finally, it was found that the prognostic model was closely related to immunotherapy and chemotherapy as well as the expression of ICIs/m6A/multidrug resistance-related genes.

CONCLUSION

The prognostic model performs excellently in predicting the prognosis of patients and provides the potential value of practical guidance for treatment.

MIAT shuttled by tumor-secreted exosomes promotes paclitaxel resistance in esophageal cancer cells by activating the TAF1/SREBF1 axis

Chemoresistance remains a major obstacle to the treatment of esophageal cancer (EC). Exosome-mediated transfer of long noncoding RNAs (lncRNAs) has recently been unveiled to correlate with the regulation of drug resistance in EC. This study aimed to investigate the physiological mechanisms by which exosome-encapsulated lncRNA myocardial infarction-associated transcript (MIAT) derived from tumor cells might mediate the paclitaxel (PTX) resistance of EC cells. First, MIAT was experimentally determined to be upregulated in PTX nonresponders and PTX-resistant EC cells. Silencing of MIAT in PTX-resistant EC cells decreased cell viability and enhanced apoptosis, corresponding to a reduced half-maximal inhibitory concentration (IC50 ) value. Next, exosomes were isolated from EC109 and EC109/T cells, and EC109 cells were cocultured with EC109/T-cell-derived exosomes. Accordingly, MIAT was revealed to be transmitted through exosomes from EC109/T cells to EC109 cells. Tumor-derived exosomes carrying MIAT increased the IC50 value of PTX and suppressed apoptosis in EC109 cells to promote PTX resistance. Furthermore, MIAT promoted the enrichment of TATA-box binding protein-associated Factor 1 (TAF1) in the promoter region of sterol regulatory element binding transcription factor 1 (SREBF1), as shown by a chromatin immunoprecipitation assay. This might be the mechanism by which MIAT could promote PTX resistance. Finally, in vivo experiments further confirmed that the knockdown of MIAT attenuated the resistance of EC cells to PTX. Collectively, these results indicate that tumor-derived exosome-loaded MIAT activates the TAF1/SREBF1 axis to induce PTX resistance in EC cells, providing a potential therapeutic target for overcoming PTX resistance in EC.

The interactions between DNA methylation machinery and long non-coding RNAs in tumor progression and drug resistance

DNA methylation is one of the main epigenetic mechanisms in cancer development and progression. Aberrant DNA methylation of CpG islands within promoter regions contributes to the dysregulation of various tumor suppressors and oncogenes; this leads to the appearance of malignant features, including rapid proliferation, metastasis, stemness, and drug resistance. The discovery of two important protein families, DNA methyltransferases (DNMTs) and Ten-eleven translocation (TET) dioxygenases, respectively, which are responsible for deregulated transcription of genes that play pivotal roles in tumorigenesis, led to further understanding of DNA methylation-related pathways. But how these enzymes can target specific genes in different malignancies; recent studies have highlighted the considerable role of Long Non-coding RNAs (LncRNAs). LncRNAs recruit these enzymes to promoter regions of genes and mediate their functions, showing great potential as therapeutic agents targeting the epigenetic regulation of various genes. Considering the importance of combining the current treatment methods, especially chemotherapies, with DNA methylation inhibitors in improving patients' outcomes, this review aimed to summarize the recent findings about the interaction between DNA methylation machinery and LncRNAs in regulating genes involved in tumorigenesis and drug resistance. So, these studies could provide insights toward developing novel strategies for cancer-targeted therapy.

LncRNAs and related molecular basis in malignant pleural mesothelioma: challenges and potential

Malignant pleural mesothelioma (MPM) is a rare but invasive cancer, which mainly arises from mesothelial tissues of pleura, peritoneum and pericardium. Despite significant advances in treatments, the prognosis of MPM patients remains poor, and the 5-year survival rate is less than 10%. Therefore, it is urgent to explore novel therapeutic targets for the treatment of MPM. Growing evidence has indicated that long non-coding RNAs (lncRNAs) potentially could be promising therapeutic targets for numerous cancers. In this regard, lncRNAs might also potentially therapeutic targets for MPM. Recent advances have been made to investigate the molecular basis of MPM. This review first provides a comprehensive overview of roles of lncRNAs in MPM and then discusses the relationship between molecular basis of MPM and MPM-related lncRNAs to implement them as promising therapeutic targets for MPM.

Long noncoding RNA SNHG6 silencing sensitized esophageal cancer cells to 5-FU via EZH2/STAT pathway

Chemotherapy was the main treatment method for esophageal cancer (EC) patients. However, chemotherapy resistance due to multiple factors is a major barrier to EC treatment. For investigating how small nucleolar RNA host gene 6 (SNHG6) affected the 5-fluorouracil (5-FU) resistance in EC as well as its possible molecular mechanism. This work conducted cell viability assay, clone formation, scratch assays together with cell apoptosis for evaluating the roles of SNHG6 and enhancer of zeste homolog 2 (EZH2, the histone-lysine N-methyltransferase). Relevant molecular mechanism was identified by RT-qPCR analysis together with Western-blot (WB) assays. Our data showed that SNHG6 expression increased in EC cells. SNHG6 promotes colony formation and migration, whereas suppresses EC cell apoptosis. SNHG6 silencing markedly promoted 5-FU-mediated suppression on KYSE150 and KYSE450 cells. Additional mechanism studies showed that SNHG6 modulating STAT3 and H3K27me3 via promoting EZH2 level. Similar to the function of SNHG6, abnormal expression of EZH2 promotes the malignancy of EC and intensifies its resistance to 5-FU. In addition, overexpression of EZH2 abolished the role of SNHG6 silencing in 5-FU sensitivity in EC cells. SNHG6 overexpression promoted malignancy of EC and increased EC cell resistance to 5-FU. Besides, further molecular mechanism studies provided a novel regulatory pathways that SNHG6 knockdown promoted EC cell sensitivity to 5-FU by modulating STAT3 and H3K27me3 via promoting EZH2 expression.

Noncoding RNAs in esophageal cancer: A glimpse into implications for therapy resistance

Esophageal cancer (EC) is one of the most common malignancies of the digestive system and has a high morbidity and mortality worldwide. Chemotherapy in combination with radiotherapy is one of the most important treatment modalities for EC. Chemoradiotherapy is currently acknowledged worldwide as being the standard treatment for locally advanced or unresectable disease. Unfortunately, due to the existence of therapy resistance, a number of EC patients fail to benefit from drug or irradiation treatment, which ultimately leads to poor outcomes. Considerable efforts have been made to explore the mechanisms underlying the therapy resistance of EC. Notably, noncoding RNAs (ncRNAs), including microRNAs (miRNAs), long noncoding RNAs (lncRNAs) and circular RNAs (circRNAs), are current research areas for the modulation of therapy responses and may serve as new targets to overcome treatment resistance in EC. Herein, we summarized the mechanisms by which ncRNAs are involved in drug and radiation resistance in EC and highlighted their role in promoting or repressing treatment resistance. Additionally, we discussed the clinical relevance of ncRNAs, which may serve as potential therapeutic targets and predictive biomarkers for EC.

Insights into the role of long non-coding RNAs in DNA methylation mediated transcriptional regulation

DNA methylation is one of the most important epigenetic mechanisms that governing regulation of gene expression, aberrant DNA methylation patterns are strongly associated with human malignancies. Long non-coding RNAs (lncRNAs) have being discovered as a significant regulator on gene expression at the epigenetic level. Emerging evidences have indicated the intricate regulatory effects between lncRNAs and DNA methylation. On one hand, transcription of lncRNAs are controlled by the promoter methylation, which is similar to protein coding genes, on the other hand, lncRNA could interact with enzymes involved in DNA methylation to affect the methylation pattern of downstream genes, thus regulating their expression. In addition, circular RNAs (circRNAs) being an important class of noncoding RNA are also found to participate in this complex regulatory network. In this review, we summarize recent research progress on this crosstalk between lncRNA, circRNA, and DNA methylation as well as their potential functions in complex diseases including cancer. This work reveals a hidden layer for gene transcriptional regulation and enhances our understanding for epigenetics regarding detailed mechanisms on lncRNA regulatory function in human cancers.

Tumor-derived extracellular vesicles confer 5-fluorouracil resistance in esophageal cancer via long noncoding RNA AC116025.2 delivery

5-Fluorouracil (5-FU) resistance is one of the main causes for treatment failure in esophageal cancer (EC). Here, we intended to elucidate the mechanism of tumor-derived extracellular vesicles (TEVs)-encapsulated long noncoding RNAs (lncRNAs) AC116025.2 in 5-FU resistance in EC. EVs were isolated from the serum samples of EC patients and HEEC, TE-1, and TE-1/5-FU cells, followed by RT-qPCR detection of AC116025.2 expression in EVs. The relationship among AC116025.2, microRNA (miR)-4496, and SEMA5A was evaluated. Next, EC cells were cocultured with EVs, followed by lentivirus transduction and plasmid transfection for studying the role of TEVs-AC116025.2 in EC cells in relation to miR-4496 and SEMA5A. Tumor formation in nude mice was applied for in vivo confirmation. Elevated AC116025.2 expression was seen in the EVs from the serum of 5-FU insensitive patients and from 5-FU-resistant EC cells. Mechanistically, AC116025.2 bound to miR-4496 that inversely targeted SEMA5A in EC cells. EVs-oe-AC116025.2 augmented EC cell viability, colony formation, and 5-FU resistance, but diminished their apoptosis through miR-4496-mediated SEMA5A. Furthermore, EVs-oe-AC116025.2 augmented tumor formation and 5-FU resistance of EC cells in vivo. Conclusively, our data offered evidence of the promoting mechanism of TEVs in the 5-FU resistance of EC by delivering AC116025.2.

MTHFR epigenetic derepression protects against diabetes cardiac fibrosis

BACKGROUND

Diabetes cardiac fibrosis is associated with altered DNA methylation of fibrogenic genes; however, the underlying mechanisms remain unclear.

OBJECTIVES

In this study, we investigate the critical role of DNA methylation aberration-associated suppression of MTHFR in diabetes cardiac fibrosis, and the protective effects of folate on diabetes cardiac fibrosis, using cultured cells, animal models, and clinical samples.

METHODS AND RESULTS

Herein, we report that DNA methylation repression of MTHFR, critically involved in diabetes cardiac fibrosis, mediates the significant protective effects of folate in a mouse model of diabetes cardiac fibrosis induced by STZ. Heart MTHFR expression was markedly suppressed in diabetes cardiac fibrosis patients and mice, accompanied by increased DNMT3A and MTHFR promoter methylation. Knockdown of DNMT3A demethylated MTHFR promoter, recovered the MTHFR loss, and alleviated the diabetes cardiac fibrosis pathology and cardiac fibroblasts pyroptosis. Mechanistically, DNMT3A epigenetically repressed MTHFR expression via methylation of the promoter. Interestingly, folate supplementation can rescue the effect of MTHFR loss in diabetes cardiac fibrosis, suggesting that inactivation of MTHFR through epigenetics is a critical mediator of diabetes cardiac fibrosis.

CONCLUSIONS

The current study identifies that MTHFR repression due to aberrant DNMT3A elevation and subsequent MTHFR promoter hypermethylation is likely an important epigenetic feature of diabetes cardiac fibrosis, and folate supplementation protects against diabetes cardiac fibrosis.

Functions and underlying mechanisms of lncRNA HOTAIR in cancer chemotherapy resistance

Chemotherapy has been one of the most important treatments for advanced cancer in recent decades. Although the sensitivity rate of initial chemotherapy is high, patients with chemotherapy resistant tumors, experience tumor recurrence. In recent years, many studies have shown that homeobox transcript antisense intergenic RNA (HOTAIR) is involved in many pathological processes including carcinogenesis. The abnormal regulation of a variety of cell functions by HOTAIR, such as apoptosis, the cell cycle, epithelial-mesenchymal transition, autophagy, self-renewal, and metabolism, is associated with chemotherapy resistance. Therefore, there is an urgent need to understand the biology and mechanism underlying the role of HOTAIR in tumor behavior and its potential as a biomarker for predicting the effect of chemotherapy. In this manuscript, we review the mechanisms underlying HOTAIR-related drug resistance and discuss the limitations of current knowledge and propose potential future directions.

Targeting purine metabolism in ovarian cancer

Purine, an abundant substrate in organisms, is a critical raw material for cell proliferation and an important factor for immune regulation. The purine de novo pathway and salvage pathway are tightly regulated by multiple enzymes, and dysfunction in these enzymes leads to excessive cell proliferation and immune imbalance that result in tumor progression. Maintaining the homeostasis of purine pools is an effective way to control cell growth and tumor evolution, and exploiting purine metabolism to suppress tumors suggests interesting directions for future research. In this review, we describe the process of purine metabolism and summarize the role and potential therapeutic effects of the major purine-metabolizing enzymes in ovarian cancer, including CD39, CD73, adenosine deaminase, adenylate kinase, hypoxanthine guanine phosphoribosyltransferase, inosine monophosphate dehydrogenase, purine nucleoside phosphorylase, dihydrofolate reductase and 5,10-methylenetetrahydrofolate reductase. Purinergic signaling is also described. We then provide an overview of the application of purine antimetabolites, comprising 6-thioguanine, 6-mercaptopurine, methotrexate, fludarabine and clopidogrel. Finally, we discuss the current challenges and future opportunities for targeting purine metabolism in the treatment-relevant cellular mechanisms of ovarian cancer.

Regulatory Roles of Noncoding RNAs in the Progression of Gastrointestinal Cancers and Health Disparities

Annually, more than a million individuals are diagnosed with gastrointestinal (GI) cancers worldwide. With the advancements in radio- and chemotherapy and surgery, the survival rates for GI cancer patients have improved in recent years. However, the prognosis for advanced-stage GI cancers remains poor. Site-specific GI cancers share a few common risk factors; however, they are largely distinct in their etiologies and descriptive epidemiologic profiles. A large number of mutations or copy number changes associated with carcinogenesis are commonly found in noncoding DNA regions, which transcribe several noncoding RNAs (ncRNAs) that are implicated to regulate cancer initiation, metastasis, and drug resistance. In this review, we summarize the regulatory functions of ncRNAs in GI cancer development, progression, chemoresistance, and health disparities. We also highlight the potential roles of ncRNAs as therapeutic targets and biomarkers, mainly focusing on their ethnicity-/race-specific prognostic value, and discuss the prospects of genome-wide association studies (GWAS) to investigate the contribution of ncRNAs in GI tumorigenesis.

Risk Stratification and Validation of Eleven Autophagy-Related lncRNAs for Esophageal Squamous Cell Carcinoma

Esophageal squamous cell carcinoma (ESCC), the most prevalent subtype of esophageal cancer, ranks sixth in cancer-related mortality, making it one of the deadliest cancers worldwide. The identification of potential risk factors for ESCC might help in implementing precision therapies. Autophagy-related lncRNAs are a group of non-coding RNAs that perform critical functions in the tumor immune microenvironment and therapeutic response. Therefore, we aimed to establish a risk model composed of autophagy-related lncRNAs that can serve as a potential biomarker for ESCC risk stratification. Using the RNA expression profile from 179 patients in the GSE53622 and GSE53624 datasets, we found 11 lncRNAs (AC004690.2, AC092159.3, AC093627.4, AL078604.2, BDNF-AS, HAND2-AS1, LINC00410, LINC00588, PSMD6-AS2, ZEB1-AS1, and LINC02586) that were co-expressed with autophagy genes and were independent prognostic factors in multivariate Cox regression analysis. The risk model was constructed using these autophagy-related lncRNAs, and the area under the receiver operating characteristic curve (AUC) of the risk model was 0.728. To confirm that the model is reliable, the data of 174 patients from The Cancer Genome Atlas (TCGA) esophageal cancer dataset were analyzed as the testing set. A nomogram for ESCC prognosis was developed using the risk model and clinic-pathological characteristics. Immune function annotation and tumor mutational burden of the two risk groups were analyzed and the high-risk group displayed higher sensitivity in chemotherapy and immunotherapy. Expression of differentially expressed lncRNAs were further validated in human normal esophageal cells and esophageal cancer cells. The constructed lncRNA risk model provides a useful tool for stratifying risk and predicting the prognosis of patients with ESCC, and might provide novel targets for ESCC treatment.

Long Noncoding RNA Hotair Promotes the Progression and Immune Escape in Laryngeal Squamous Cell Carcinoma through MicroRNA-30a/GRP78/PD-L1 Axis

Homeobox (HOX) transcript antisense RNA (Hotair) is elevated in many cancers significantly. However, the oncogenic role of Hotair in human laryngeal squamous cell carcinoma (LSCC) is still unknown. Thus, we explored the expression profile of Hotair and its function in LSCC. We observed high expression levels of Hotair in six LSCC cell lines compared to the human nasopharyngeal epithelial cell line. Knockdown of Hotair inhibited proliferation and enhanced apoptosis of Tu212 and Hep-2 cell lines in vitro. Moreover, the overexpression of hsa-miR-30a-5p inhibited the expression of GRP78 and PD-L1, but Hotair overexpression in LSCC cells rescues both proteins. Furthermore, the impacts of hsa-miR-30a-5p upregulation on the apoptosis and proliferation of LSCC cells were rescued by overexpression of Hotair. Finally, we combined si-Hotair and a VEGF inhibitor to treat LSCC cells in vitro or in vivo and surprisingly observed a significant inhibition of LSCC growth. In summary, these results indicate that Hotair displays an oncogenic role in both malignancy and immune escape in LSCC related to hsa-miR-30a-5p/GRP78/PD-L1 signaling. Therefore, Hotair may be a potential target for treating LSCC.

LncRNA-mediated DNA methylation: an emerging mechanism in cancer and beyond

DNA methylation is one of the most important epigenetic mechanisms to regulate gene expression, which is highly dynamic during development and specifically maintained in somatic cells. Aberrant DNA methylation patterns are strongly associated with human diseases including cancer. How are the cell-specific DNA methylation patterns established or disturbed is a pivotal question in developmental biology and cancer epigenetics. Currently, compelling evidence has emerged that long non-coding RNA (lncRNA) mediates DNA methylation in both physiological and pathological conditions. In this review, we provide an overview of the current understanding of lncRNA-mediated DNA methylation, with emphasis on the roles of this mechanism in cancer, which to the best of our knowledge, has not been systematically summarized. In addition, we also discuss the potential clinical applications of this mechanism in RNA-targeting drug development.

Integrated Dissection of lncRNA-miRNA-mRNA Pairs and Potential Regulatory Role of lncRNA PCAT19 in Lung Adenocarcinoma

Lung adenocarcinoma (LUAD) is the main cause of cancer-related deaths worldwide. Long noncoding RNAs have been reported to play an important role in various cancers due to their special functions. Therefore, identifying the lncRNAs involved in LUAD tumorigenesis and development can help improve therapeutic strategies. The TCGA-LUAD RNA expression profile was downloaded from The Cancer Genome Atlas, and a total of 49 differential lncRNAs, 112 differential miRNAs, and 2,953 differential mRNAs were screened. Through Kaplan–Meier curves, interaction networks, hub RNAs (lncRNAs, miRNAs, and mRNAs) were obtained. These hub genes are mainly involved in cell proliferation, cell cycle, lung development, and tumor-related signaling pathways. Two lncRNAs (SMIM25 and PCAT19) more significantly related to the prognosis of LUAD were screened by univariate Cox analysis, multivariate Cox analysis, and risk model analysis. The qPCR results showed that the expression levels of SMIM25 and PCAT19 were downregulated in clinical tissues, A549 and SPC-A1 cells, which were consistent with the bioinformatics analysis results. Subsequently, the PCAT19/miR-143-3p pairs were screened through the weighted gene co-expression network analysis and miRNA-lncRNA regulatory network. Dual luciferase detection confirmed that miR-143-3p directly targets PCAT19, and qPCR results indicated that the expression of the two is positively correlated. Cell function tests showed that overexpression of PCAT19 could significantly inhibit the proliferation, migration, and invasion of A549 and SPC-A1 cells. In contrast, knockout of PCAT19 can better promote the proliferation and migration of A549 and SPC-A1 cells. The expression of PCAT19 was negatively correlated with tumor grade, histological grade, and tumor mutation load in LUAD. In addition, co-transfection experiments confirmed that the miR-143-3p mimic could partially reverse the effect of PCAT19 knockout on the proliferation of A549 and SPC-A1 cells. In summary, PCAT19 is an independent prognostic factor in patients with LUAD that can regulate the proliferation, migration, and invasion of LUAD cells and may be a potential biomarker for the diagnosis of LUAD. PCAT19/miR-143-3p plays a very important regulatory role in the occurrence and development of LUAD.

Functional Peptides Encoded by Long Non-Coding RNAs in Gastrointestinal Cancer

Gastrointestinal cancer is by far the most common malignancy and the most common cause of cancer-related deaths worldwide. Recent studies have shown that long non-coding RNAs (lncRNAs) play an important role in the epigenetic regulation of cancer cells and regulate tumor progression by affecting chromatin modifications, gene transcription, translation, and sponge to miRNAs. In particular, lncRNA has recently been found to possess open reading frame (ORF), which can encode functional small peptides or proteins. These peptides interact with its targets to regulate transcription or the signal axis, thus promoting or inhibiting the occurrence and development of tumors. In this review, we summarize the involvement of lncRNAs and the function of lncRNAs encoded small peptides in gastrointestinal cancer.

Novel Implications of MicroRNAs, Long Non-coding RNAs and Circular RNAs in Drug Resistance of Esophageal Cancer

Esophageal cancer is the eighth most common malignancy and the sixth leading cause of cancer-related deaths worldwide. Chemotherapy based on platinum drugs, 5-fluorouracil, adriamycin, paclitaxel, gemcitabine, and vinorelbine, as well as targeted treatment and immunotherapy with immune checkpoint inhibitors improved the prognosis in a portion of patients with advanced esophageal cancer. Unfortunately, a number of esophageal cancer patients develop drug resistance, resulting in poor outcomes. Multiple mechanisms contributing to drug resistance of esophageal cancer have been reported. Notably, non-coding RNAs (ncRNAs), including microRNAs (miRNAs), long non-coding RNAs (lncRNAs) and circular RNAs (circRNAs), have been identified to play crucial roles in modulating esophageal cancer drug resistance. In the present review, we highlight the underlying mechanisms how miRNAs, lncRNAs, and circRNAs impact the drug resistance of esophageal cancer. Several miRNAs, lncRNAs, and circRNAs may have potential clinical implications as novel biomarkers and therapeutic targets for esophageal cancer.

Prognostic value of immune-related lncRNA pairs in patients with bladder cancer

BACKGROUND

The characteristics of immune-related long non-coding ribonucleic acids (ir-lncRNAs), regardless of their specific levels, have important implications for the prognosis of patients with bladder cancer.

METHODS

Based on The Cancer Genome Atlas database, original transcript data were analyzed. The ir-lncRNAs were obtained using a coexpression method, and their differentially expressed pairs (DE-ir-lncRNAs) were identified by univariate analysis. The lncRNA pairs were verified using a Lasso regression test. Thereafter, receiver operating characteristic curves were generated, and an optimal risk model was established. The clinical value of the model was verified through the analysis of patient survival rates, clinicopathological characteristics, presence of tumor-infiltrating immune cells, and chemotherapy efficacy evaluation.

RESULTS

In total, 49 pairs of DE-ir-lncRNAs were identified, of which 21 were included in the Cox regression model. A risk regression model was established on the premise of not involving the specific expression value of the transcripts.

CONCLUSIONS

The method and model used in this study have important clinical predictive value for bladder cancer and other malignant tumors.

5-Fluorouracil: A Narrative Review on the Role of Regulatory Mechanisms in Driving Resistance to This Chemotherapeutic Agent

5-fluorouracil (5-FU) is among the mostly administrated chemotherapeutic agents for a wide variety of neoplasms. Non-coding RNAs have a central impact on the determination of the response of patients to 5-FU. These transcripts via modulation of cancer-related pathways, cell apoptosis, autophagy, epithelial-mesenchymal transition, and other aspects of cell behavior can affect cell response to 5-FU. Modulation of expression levels of microRNAs or long non-coding RNAs may be a suitable approach to sensitize tumor cells to 5-FU treatment via modulating multiple biological signaling pathways such as Hippo/YAP, Wnt/β-catenin, Hedgehog, NF-kB, and Notch cascades. Moreover, there is an increasing interest in targeting these transcripts in various kinds of cancers that are treated by 5-FU. In the present article, we provide a review of the function of non-coding transcripts in the modulation of response of neoplastic cells to 5-FU.

LncRNA CBR3-AS1 regulates of breast cancer drug sensitivity as a competing endogenous RNA through the JNK1/MEK4-mediated MAPK signal pathway

Background

Adriamycin (ADR) resistance is one of the main obstacles to improving the clinical prognosis of breast cancer patients. Long noncoding RNAs (lncRNAs) can regulate cell behavior, but the role of these RNAs in the anti-ADR activity of breast cancer remains unclear. Here, we aim to investigate the imbalance of a particular long noncoding RNA, lncRNA CBR3 antisense RNA 1 (CBR3-AS1), and its role in ADR resistance.

Methods

Microarray analysis of ADR-resistant breast cancer cells was performed to identify CBR3-AS1. CCK-8 and colony formation assays were used to detect the sensitivity of breast cancer cells to ADR. Dual-luciferase reporter, RNA pulldown, IHC and western blot analyses were used to verify the relationship between the expression of CBR3-AS1, miRNA and target genes. For in vivo experiments, the effect of CBR3-AS1 on breast cancer resistance was observed in a xenograft tumor model. The role of CBR3-AS1 in influencing ADR sensitivity was verified by clinical breast cancer specimens from the TCGA, CCLE, and GDSC databases.

Results

We found that CBR3-AS1 expression was significantly increased in breast cancer tissues and was closely correlated with poor prognosis. CBR3-AS1 overexpression promoted ADR resistance in breast cancer cells in vitro and in vivo. Mechanistically, we identified that CBR3-AS1 functioned as a competitive endogenous RNA by sponging miR-25-3p. MEK4 and JNK1 of the MAPK pathway were determined to be direct downstream proteins of the CBR3-AS1/miR-25-3p axis in breast cancer cells.

Conclusions

In summary, our findings demonstrate that CBR3-AS1 plays a critical role in the chemotherapy resistance of breast cancer by mediating the miR-25-3p and MEK4/JNK1 regulatory axes. The potential of CBR3-AS1 as a targetable oncogene and therapeutic biomarker of breast cancer was identified.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-021-01844-7.

The Role of Non-Coding RNAs as Prognostic Factor, Predictor of Drug Response or Resistance and Pharmacological Targets, in the Cutaneous Squamous Cell Carcinoma

Cutaneous squamous cell carcinoma (CSCC) is the most common keratinocyte-derived skin cancer in the Caucasian population. Exposure to UV radiations (UVRs) represents the main risk carcinogenesis, causing a considerable accumulation of DNA damage in epidermal keratinocytes with an uncontrolled hyperproliferation and tumor development. The limited and rarely durable response of CSCC to the current therapeutic options has led researchers to look for new therapeutic strategies. Recently, the multi-omics approaches have contributed to the identification and prediction of the key role of non-coding RNAs (ncRNAs), such as microRNAs (miRNAs), circularRNAs (circRNAs) and long non-coding RNAs (lncRNAs) in the regulation of several cellular processes in different tumor types, including CSCC. ncRNAs can modulate transcriptional and post-transcriptional events by interacting either with each other or with DNA and proteins, such as transcription factors and RNA-binding proteins. In this review, the implication of ncRNAs in tumorigenesis and their potential role as diagnostic biomarkers and therapeutic targets in human CSCC are reported.