Knockdown of long non-coding RNA HOTAIR inhibits cisplatin resistance of gastric cancer cells through inhibiting the PI3K/Akt and Wnt/β-catenin signaling pathways by up-regulating miR-34a

HOTAIR Promotes the Hyperactivation of PI3K/Akt and Wnt/β-Catenin Signaling Pathways via PTEN Hypermethylation in Cervical Cancer

The mechanisms underlying the sustained activation of the PI3K/AKT and Wnt/β-catenin pathways mediated by HOTAIR in cervical cancer (CC) have not been extensively described. To address this knowledge gap in the literature, we explored the interactions between these pathways by driving HOTAIR expression levels in HeLa cells. Our findings reveal that HOTAIR is a key regulator in sustaining the activation of both signaling pathways. Specifically, altering HOTAIR expression-either by knockdown or overexpression-significantly influenced the transcriptional activity of the PI3K/AKT and Wnt/β-catenin pathways. Additionally, we discovered that HIF1α directly induces HOTAIR transcription, which in turn leads to the epigenetic silencing of the PTEN promoter via DNMT1. This process leads to the sustained activation of both pathways, highlighting a novel regulatory axis involving HOTAIR and HIF1α in cervical cancer. Our results suggest a new model in which HOTAIR sustains reciprocal activation of the PI3K/AKT and Wnt/β-catenin pathways through the HOTAIR/HIF1α axis, thereby contributing to the oncogenic phenotype of cervical cancer.

Long noncoding RNAs as potential targets for overcoming chemoresistance in upper gastrointestinal cancers

In the last decade, researchers have paid much attention to the role of noncoding RNA molecules in human diseases. Among the most important of these molecules are LncRNAs, which are RNA molecules with a length of more than 200 nucleotides. LncRNAs can regulate gene expression through various mechanisms, such as binding to DNA sequences and interacting with miRNAs. Studies have shown that LncRNAs may be valuable therapeutic targets in treating various cancers, including upper-gastrointestinal cancers. Upper gastrointestinal cancers, mainly referring to esophageal and gastric cancers, are among the deadliest gastrointestinal cancers. Despite notable advances, traditional chemotherapy remains a common strategy for treating these cancers. However, chemoresistance poses a significant obstacle to the effective treatment of upper gastrointestinal cancers, resulting in a low survival rate. Chemoresistance arises from various events, such as the enhancement of efflux and detoxification of chemotherapy agents, reduction of drug uptake, alteration of drug targeting, reduction of prodrug activation, strengthening of EMT and stemness, and the attenuation of apoptosis in cancerous cells. Tumor microenvironment also plays an important role in chemoresistance. Interestingly, a series of studies have revealed that LncRNAs can influence important mechanisms associated with some of the aforementioned events and may serve as promising targets for mitigating chemoresistance in upper gastrointestinal cancers. In this review paper, following a concise overview of chemoresistance mechanisms in upper gastrointestinal cancers, we will review the most intriguing findings of these investigations in detail.

The Role of Circular RNA in the Pathogenesis of Chemotherapy-Induced Cardiotoxicity in Cancer Patients: Focus on the Pathogenesis and Future Perspective

Cardiotoxicity is a serious challenge cancer patients face today. Various factors are involved in cardiotoxicity. Circular RNAs (circRNAs) are one of the effective factors in the occurrence and prevention of cardiotoxicity. circRNAs can lead to increased proliferation, apoptosis, and regeneration of cardiomyocytes by regulating the molecular pathways, as well as increasing or decreasing gene expression; some circRNAs have a dual role in cardiomyocyte regeneration or death. Identifying each of the pathways related to these processes can be effective on managing patients and preventing cardiotoxicity. In this study, an overview of the molecular pathways involved in cardiotoxicity by circRNAs and their effects on the downstream factors have been discussed.

Expression of Pivotal Long Non-coding RNAs Implicated in Gastric Cancer: A Bioinformatic and Clinical Study

Gastric cancer (GC) is a prominent public health issue and ranks as the third most prevalent cause of cancer-related mortality on a global scale. The role of long non-coding RNAs (lncRNAs) in cancer is not yet fully understood, particularly in relation to GC development. The objective of this study was to examine the expression levels of lncRNAs in GC tissues using a bioinformatics-based ranking approach. A bioinformatics methodology was employed to prioritize lncRNAs that are hypothesized to play a role in GC tumorigenesis. Moreover, a selection was made for experimental validation of the highest-ranked lncRNAs, which include HCG18, OIP5-AS1, FGD5-AS1, and NORAD. Additionally, quantitative real-time polymerase chain reaction (qRT-PCR) was employed to confirm the results obtained from bioinformatics analysis in a total of 35 GC samples and their corresponding adjacent non-tumoral samples. Receiver operating characteristic (ROC) curves and the corresponding area under the ROC curve (AUC) were utilized to evaluate the diagnostic efficacy of the lncRNAs. The bioinformatics analysis revealed that the lncRNA HCG18 is the highest-ranked lncRNA associated with GC. Furthermore, the expression levels of HCG18, OIP5-AS1, FGD5-AS1, and NORAD were found to be significantly elevated in GC samples when compared to adjacent non-tumoral samples. The calculated values for the AUC of HCG18, OIP5-AS1, FGD5-AS1, and NORAD were 0.80, 0.74, 0.73, and 0.71, respectively. The results of the study indicate that the lncRNAs HCG18, OIP5-AS1, FGD5-AS1, and NORAD may play a role in the development of GC. Additionally, the present study revealed that utilizing bioinformatic techniques can prove to be a highly effective strategy in identifying potential lncRNAs pertinent to the progression of GC.

Wnt signaling and tumors (Review)

Wnt signaling is a highly conserved evolutionary pathway that plays a key role in regulation of embryonic development, as well as tissue homeostasis and regeneration. Abnormalities in Wnt signaling are associated with tumorigenesis and development, leading to poor prognosis in patients with cancer. However, the pharmacological effects and mechanisms underlying Wnt signaling and its inhibition in cancer treatment remain unclear. In addition, potential side effects of inhibiting this process are not well understood. Therefore, the present review outlines the role of Wnt signaling in tumorigenesis, development, metastasis, cancer stem cells, radiotherapy resistance and tumor immunity. The present review further identifies inhibitors that target Wnt signaling to provide a potential novel direction for cancer treatment. This may facilitate early application of safe and effective drugs targeting Wnt signaling in clinical settings. An in-depth understanding of the mechanisms underlying inhibition of Wnt signaling may improve the prognosis of patients with cancer.

Identification and validation of the role of ZNF281 in 5-fluorouracil chemotherapy of gastric cancer

BACKGROUND

The early diagnosis of gastric cancer (GC) and overcoming chemotherapy resistance is challenging. The aberrant expression of zinc finger protein 281 (ZNF281) and the over-activation of the Wnt/β-catenin pathway are oncogenic factors and confer tumor chemoresistance. ZNF281 modulates the Wnt/β-catenin pathway to influence malignant tumor behavior. However, the role of ZNF281 in GC chemotherapy and the relationship with the Wnt/β-catenin pathway have not been elucidated by researchers.

METHODS

We explored differences in ZNF281 expression in Pan-cancer and normal tissues, the effect of its expression on prognosis of patients treated with 5-fluorouracil (5-FU). Cox regression was utilized to determine whether ZNF281 is an independent prognostic factor. Enrichment analysis was performed to explore the mechanism underlying ZNF281's role in 5-FU treatment. We assessed the relationship between ZNF281 and the tumour microenvironment (TME) and combined bulk-RNA and single-cell RNA data to analyse the relationship between ZNF281 and immune infiltration. In vitro experiments verified the effects of ZNF281 knockdown on proliferation, invasion, migration, apoptosis, DNA damage of GC cells with 5-FU treated and the Wnt/β-catenin pathway proteins.

RESULTS

ZNF281 was highly expressed in seven cancers and correlates with the prognosis. It is an independent prognostic factor in 5-FU treatment. ZNF281 correlates with TME score, CD8T cell abundance. ZNF281 is primarily associated with DNA repair and the Wnt/β-catenin pathway. ZNF281 knockdown enhanced the effect of 5-FU on phenotypes of GC cells.

CONCLUSION

We identified and verified ZNF281 as one of the potential influencing factors of 5-FU treatment in GC and may be associated with the Wnt/β-catenin pathway. Low ZNF281 may contribute to improved 5-FU sensitivity in GC patients.

The role of HOTAIR in the modulation of resistance to anticancer therapy

Leading anti-tumour therapeutic strategies typically involve surgery and radiotherapy for locally advanced (non-metastatic) cancers, while hormone therapy, chemotherapy, and molecular targeted therapy are the current treatment options for metastatic cancer. Despite the initially high sensitivity rate to anticancer therapies, a large number of patients develop resistance, leading to a poor prognosis. The mechanisms related to drug resistance are highly complex, and long non-coding RNAs appear to play a crucial role in these processes. Among these, the lncRNA homeobox transcript antisense intergenic RNA (HOTAIR), widely implicated in cancer initiation and progression, likewise plays a significant role in anticancer drug resistance. It can modulate cell activities such as proliferation, apoptosis, hypoxia, autophagy, as well as epithelial-mesenchymal transition, thereby contributing to the development of resistant tumour cells. In this manuscript, we describe different mechanisms of antitumor drug resistance in which HOTAIR is involved and suggest its potential as a therapeutic predictive biomarker for the management of cancer patients.

Long Non-Coding RNAs in Drug Resistance of Gastric Cancer: Complex Mechanisms and Potential Clinical Applications

Gastric cancer (GC) ranks as the third most prevalent malignancy and a leading cause of cancer-related mortality worldwide. However, the majority of patients with GC are diagnosed at an advanced stage, highlighting the urgent need for effective perioperative and postoperative chemotherapy to prevent relapse and metastasis. The current treatment strategies have limited overall efficacy because of intrinsic or acquired drug resistance. Recent evidence suggests that dysregulated long non-coding RNAs (lncRNAs) play a significant role in mediating drug resistance in GC. Therefore, there is an imperative to explore novel molecular mechanisms underlying drug resistance in order to overcome this challenging issue. With advancements in deep transcriptome sequencing technology, lncRNAs-once considered transcriptional noise-have garnered widespread attention as potential regulators of carcinogenesis, including tumor cell proliferation, metastasis, and sensitivity to chemo- or radiotherapy through multiple regulatory mechanisms. In light of these findings, we aim to review the mechanisms by which lncRNAs contribute to drug therapy resistance in GC with the goal of providing new insights and breakthroughs toward overcoming this formidable obstacle.

Bibliometric and visualized analysis of global research on microRNAs in gastric cancer: from 2013 to 2023

Gastric cancer (GC) imposes a heavy burden on global public health, and microRNAs (miRNAs) play a crucial role in the diagnosis and treatment of GC. Therefore, it is necessary to clarify the hotspots and frontiers in the field of miRNAs in GC to guide future research. A total of 2,051 publications related to miRNAs in GC from January 2013 to December 2023 were searched from the Web of Science Core Collection database. CiteSpace was used to identify research hotspots and delineate developmental trends. In the past decade, China, Nanjing Medical University, and Ba Yi were the most contributing research country, institute, and author in this field, respectively. The role of miRNAs as biomarkers in GC, the mechanism of miRNAs in the progression of GC, and the impact of the mutual effects between miRNAs and Helicobacter pylori on GC have been regarded as the research hotspots. The mechanisms of miRNAs on glucose metabolism and the application of the roles of circular RNAs as miRNA sponges in GC treatment will likely be frontiers. Overall, this study called for strengthened cooperation to identify targets and therapeutic regimes for local specificity and high-risk GC types, and to promote the translation of research results into clinical practice.

Non-Coding RNA as Biomarkers and Their Role in the Pathogenesis of Gastric Cancer-A Narrative Review

Non-coding RNAs (ncRNAs) represent a broad family of molecules that regulate gene expression, including microRNAs, long non-coding RNAs and circular RNAs, amongst others. Dysregulated expression of ncRNAs alters gene expression, which is implicated in the pathogenesis of several malignancies and inflammatory diseases. Gastric cancer is the fifth most frequently diagnosed cancer and the fourth most common cause of cancer-related death. Studies have found that altered expression of ncRNAs may contribute to tumourigenesis through regulating proliferation, apoptosis, drug resistance and metastasis. This review describes the potential use of ncRNAs as diagnostic and prognostic biomarkers. Moreover, we discuss the involvement of ncRNAs in the pathogenesis of gastric cancer, including their interactions with the members of major signalling pathways.

MicroRNA-34 and gastrointestinal cancers: a player with big functions

It is commonly assumed that gastrointestinal cancer is the most common form of cancer across the globe and is the leading contributor to cancer-related death. The intricate mechanisms underlying the growth of GI cancers have been identified. It is worth mentioning that both non-coding RNAs (ncRNAs) and certain types of RNA, such as circular RNAs (circRNAs), long non-coding RNAs (lncRNAs), and microRNAs (miRNAs), can have considerable impact on the development of gastrointestinal (GI) cancers. As a tumour suppressor, in the group of short non-coding regulatory RNAs is miR-34a. miR-34a silences multiple proto-oncogenes at the post-transcriptional stage by targeting them, which inhibits all physiologically relevant cell proliferation pathways. However, it has been discovered that deregulation of miR-34a plays important roles in the growth of tumors and the development of cancer, including invasion, metastasis, and the tumor-associated epithelial-mesenchymal transition (EMT). Further understanding of miR-34a's molecular pathways in cancer is also necessary for the development of precise diagnoses and effective treatments. We outlined the most recent research on miR-34a functions in GI cancers in this review. Additionally, we emphasize the significance of exosomal miR-34 in gastrointestinal cancers.

Research Progress of Long Non-Coding RNA in Tumor Drug Resistance: A New Paradigm

In the past few decades, chemotherapy has been one of the most effective cancer treatment options. Drug resistance is currently one of the greatest obstacles to effective cancer treatment. Even though drug resistance mechanisms have been extensively investigated, they have not been fully elucidated. Recent genome-wide investigations have revealed the existence of a substantial quantity of long non-coding RNAs (lncRNAs) transcribed from the human genome, which actively participate in numerous biological processes, such as transcription, splicing, epigenetics, the cell cycle, cell differentiation, development, pluripotency, immune microenvironment. The abnormal expression of lncRNA is considered a contributing factor to the drug resistance. Furthermore, drug resistance may be influenced by genetic and epigenetic variations, as well as individual differences in patient treatment response, attributable to polymorphisms in metabolic enzyme genes. This review focuses on the mechanism of lncRNAs resistance to target drugs in the study of tumors with high mortality, aiming to establish a theoretical foundation for targeted therapy.

Deciphering drug resistance in gastric cancer: Potential mechanisms and future perspectives

Gastric cancer (GC) is a malignant tumor that originates from the epithelium of the gastric mucosa. The latest global cancer statistics show that GC ranks fifth in incidence and fourth in mortality among all cancers, posing a serious threat to public health. While early-stage GC is primarily treated through surgery, chemotherapy is the frontline option for advanced cases. Currently, commonly used chemotherapy regimens include FOLFOX (oxaliplatin + leucovorin + 5-fluorouracil) and XELOX (oxaliplatin + capecitabine). However, with the widespread use of chemotherapy, an increasing number of cases of drug resistance have emerged. This article primarily explores the potential mechanisms of chemotherapy resistance in GC patients from five perspectives: cell death, tumor microenvironment, non-coding RNA, epigenetics, and epithelial-mesenchymal transition. Additionally, it proposes feasibility strategies to overcome drug resistance from four angles: cancer stem cells, tumor microenvironment, natural products, and combined therapy. The hope is that this article will provide guidance for researchers in the field and bring hope to more GC patients.

Emerging roles of HOTAIR lncRNA in the pathogenesis and prognosis of cardiovascular diseases

Highlights HOTAIR, a long noncoding RNA, plays a role in the regulation of proteins involved in the pathogenesis of cardiovascular disease. Furthermore, it has been identified as a biomarker of this type of disease. Several factors and cells contribute to atherosclerosis, a progressive disease. However, the prognosis of HOTAIR in this disease varies depending on the path in which it plays a role. For this condition, there is no single prognosis to consider.

Mechanism of PWAR6 regulating cisplatin drug sensitivity in non-small cell lung cancer through miR-577/PHACTR1

lncRNA Prader Willi/Angelman Region RNA 6 (PWAR6) is considered to play a protective lncRNA in glioma, but, the role of PWAR6 in the occurrence and cisplatin resistance of non-small cell lung cancer (NSCLC) is elusive. In the study, we aimed to assess the role of PWAR6 in the cisplatin resistance of NSCLC. Based on the oebiotech and TargetScanHuman database, we predicted the interaction between PWAR6, miR-577 and PHACTR1. We then used small interfering RNA (siRNA), miRNA mimics and dual-luciferase reporter assay to explore the regulatory role of PWAR6/miR-577PHACTR1. Based on the online database, miR-577 can interact with PWAR6 and PHACTR1. Soon afterwards, we observed that the expression of PWAR6 and PHACTR1 was increased, while miR-577 expression was decreased in A549/DDP cells. And the cell viability was decreased, while cell apoptosis was increased in A549/DDP cells. What's more, PWAR6 knockdown can promote the expression of miR-577 and inhibit the expression of PHACTR1. PWAR6 knockdown elevated cell proliferation and reduced cell apoptosis of A549/DDP cells. Interestingly, we found that miR-577 can interact with PHACTR1 to regulate the proliferation and apoptosis of A549/DDP cells. To conclude, we speculated that PWAR6 knockdown elevated cell proliferation and reduced cell apoptosis of A549/DDP cells via miR-577/PHACTR1, providing the theoretical basis for the clinical treatment of NSCLC patients.

Exosomal long non-coding RNAs in glioblastoma

Glioblastoma multiforme (GBM) is the most prevalent primary tumor found in the central nervous system, accounting for 70% of all adult brain tumors. The median overall survival rate is one year post-diagnosis with treatment, and only four months without treatment. Current GBM diagnostic methods, such as magnetic resonance imaging (MRI), surgery, and brain biopsies, have limitations. These include difficulty distinguishing between tumor recurrence and post-surgical necrotic regions, and operative risks associated with obtaining histological samples through direct surgery or biopsies. Consequently, there is a need for rapid, inexpensive, and minimally invasive techniques for early diagnosis and improved subsequent treatment. Research has shown that tumor-derived exosomes containing various long non-coding RNAs (lncRNAs) play critical regulatory roles in immunomodulation, cancer metastasis, cancer development, and drug resistance in GBM. They regulate genes that enhance cancer growth and progression and alter the expression of several key signaling pathways. Due to the specificity and sensitivity of exosomal lncRNAs, they have the potential to be used as biomarkers for early diagnosis and prognosis, as well as to monitor a patient's response to chemotherapy for GBM. In this review, we discuss the role of exosomal lncRNAs in the pathogenesis of GBM and their potential clinical applications for early diagnosis.

Non-coding RNAs as potential therapeutic targets for receptor tyrosine kinase signaling in solid tumors: current status and future directions

This review article presents an in-depth analysis of the current state of research on receptor tyrosine kinase regulatory non-coding RNAs (RTK-RNAs) in solid tumors. RTK-RNAs belong to a class of non-coding RNAs (nc-RNAs) responsible for regulating the expression and activity of receptor tyrosine kinases (RTKs), which play a critical role in cancer development and progression. The article explores the molecular mechanisms through which RTK-RNAs modulate RTK signaling pathways and highlights recent advancements in the field. This include the identification of potential new RTK-RNAs and development of therapeutic strategies targeting RTK-RNAs. While the review discusses promising results from a variety of studies, encompassing in vitro, in vivo, and clinical investigations, it is important to acknowledge the challenges and limitations associated with targeting RTK-RNAs for therapeutic applications. Further studies involving various cancer cell lines, animal models, and ultimately, patients are necessary to validate the efficacy of targeting RTK-RNAs. The specificity of ncRNAs in targeting cellular pathways grants them tremendous potential, but careful consideration is required to minimize off-target effects, the article additionally discusses the potential clinical applications of RTK-RNAs as biomarkers for cancer diagnosis, prognosis, and treatment. In essence, by providing a comprehensive overview of the current understanding of RTK-RNAs in solid tumors, this review emphasizes their potential as therapeutic targets for cancer while acknowledging the associated challenges and limitations.

HOTAIR: A key regulator of the Wnt/β-catenin signaling cascade in cancer progression and treatment

The long non-coding RNA (lncRNA) HOTAIR occupies a central position in the complex domain of cancer biology, particularly concerning its intricate interplay with the Wnt/β-catenin signaling pathway. This comprehensive review explores the multifaceted interactions between HOTAIR and the Wnt/β-catenin cascade, elucidating their profound function in cancer growth, progression, and therapeutic strategies. The study commences by underscoring the pivotal role of the Wnt/β-catenin cascade in governing essential cellular activities, emphasizing its dysregulation as a linchpin in cancer initiation and advancement. It introduces HOTAIR as a crucial regulatory entity, influencing gene expression in both healthy and diseased. The core of this review plunges into the intricacies of HOTAIR's engagement with Wnt/β-catenin signaling. It unravels how HOTAIR, through epigenetic modifications and transcriptional control, exerts its influence over key pathway constituents, including β-catenin, Wnt ligands, and target genes. This influence drives unchecked cancer cell growth, invasion, and metastasis. Furthermore, the review underscores the clinical significance of the HOTAIR-Wnt/β-catenin interplay, elucidating its associations with diverse cancer subtypes, patient prognoses, and prospects as a therapy. It provides insights into ongoing research endeavors to develop HOTAIR-targeted treatments and initiatives to facilitate aberrant Wnt/β-catenin activation. Concluding on a forward-looking note, the article accentuates the broader implications of HOTAIR's involvement in cancer biology, including its contributions to therapy resistance and metastatic dissemination. It underscores the importance of delving deeper into these intricate molecular relationships to pave the way for groundbreaking cancer treatment.

Overexpression of LINC00853 enhances tumorigenesis and metastasis of gastric cancer

Gastric cancer (GC) is a rising global health issue, with increasing incidence and mortality rates. The pathogenesis of GC is highly complex and involves a combination of genetic and environmental factors. Therefore, identifying new genes and pathways that contribute to the development and progression of GC is essential for improving diagnosis and treatment outcomes. Long noncoding RNAs (lncRNAs) have recently emerged as a promising area of research in understanding the molecular mechanisms underlying various cancers, including GC. These RNA molecules are longer than 200 nucleotides and do not code proteins. Although initially considered "junk DNA", lncRNAs have been demonstrated to play significant roles in various biological processes, including cell proliferation, differentiation, and apoptosis, as well as in the pathogenesis of various cancers. In this study, we screened clinical specimens for a novel lncRNA, LINC00853, which showed high expression in GC tissues and promoted the proliferation, migration, and invasion of GC cells. Furthermore, in vivo experiments confirmed its ability to facilitate the growth and metastasis of GC. These results suggest that LINC00853 plays a crucial role in the development and progression of GC.

The long non-coding RNA HOTAIR contributes to joint-specific gene expression in rheumatoid arthritis

Although patients with rheumatoid arthritis (RA) typically exhibit symmetrical joint involvement, some patients develop alternative disease patterns in response to treatment, suggesting that different molecular mechanism may underlie disease progression depending on joint location. Here, we identify joint-specific changes in RA synovium and synovial fibroblasts (SF) between knee and hand joints. We show that the long non-coding RNA HOTAIR, which is only expressed in knee SF, regulates more than 50% of this site-specific gene expression in SF. HOTAIR is downregulated after stimulation with pro-inflammatory cytokines and is expressed at lower levels in knee samples from patients with RA, compared with osteoarthritis. Knockdown of HOTAIR in knee SF increases PI-Akt signalling and IL-6 production, but reduces Wnt signalling. Silencing HOTAIR inhibits the migratory function of SF, decreases SF-mediated osteoclastogenesis, and increases the recruitment of B cells by SF. We propose that HOTAIR is an important epigenetic factor in joint-specific gene expression in RA.

Evaluation of Long Non-coding RNA (LncRNA) in the Pathogenesis of Chemotherapy Resistance in Cervical Cancer: Diagnostic and Prognostic Approach

Cervical cancer (CC), caused by human papillomavirus (HPV), is a leading cause of female malignancies worldwide. Therefore, understanding the underlying mechanisms of CC development and identifying novel therapeutic targets are significantly important. Cisplatin resistance is a significant challenge in the management of CC. Recent studies highlighted the critical role of long non-coding RNAs (lncRNAs) in modulation of cisplatin resistance. This comprehensive review aims to collect the current understanding roles of lncRNAs and their involvement in cisplatin resistance in CC by highlighting key processes of cancer progression, including apoptosis, proliferation, angiogenesis and epithelial-to-mesenchymal transition (EMT). We discussed the role of lncRNA in CC resistance to cisplatin through molecular pathways and examined gene expression changes. We also discussed treatment strategies and factors that reduce CC resistance to cisplatin by targeting them.

Role of non-coding RNAs as new therapeutic targets in regulating the EMT and apoptosis in metastatic gastric and colorectal cancers

Colorectal cancer (CRC) and gastric cancer (GC), are the two most common cancers of the gastrointestinal tract, and are serious health concerns worldwide. The discovery of more effective biomarkers for early diagnosis, and improved patient prognosis is important. Non-coding RNAs (ncRNAs), including microRNAs (miRNAs) and long non-coding RNAs (lncRNAs), can regulate cellular processes such as apoptosis and the epithelial-mesenchymal transition (EMT) leading to progression and resistance of GC and CRC tumors. Moreover these pathways (apoptosis and EMT) may serve as therapeutic targets, to prevent metastasis, and to overcome drug resistance. A subgroup of ncRNAs is common to both GC and CRC tumors, suggesting that they might be used as biomarkers or therapeutic targets. In this review, we highlight some ncRNAs that can regulate EMT and apoptosis as two opposite mechanisms in cancer progression and metastasis in GC and CRC. A better understanding of the biological role of ncRNAs could open up new avenues for the development of personalized treatment plans for GC and CRC patients.

A state-of-art of underlying molecular mechanisms and pharmacological interventions/nanotherapeutics for cisplatin resistance in gastric cancer

The fourth common reason of death among patients is gastric cancer (GC) and it is a dominant tumor type in Ease Asia. One of the problems in GC therapy is chemoresistance. Cisplatin (CP) is a platinum compound that causes DNA damage in reducing tumor progression and viability of cancer cells. However, due to hyperactivation of drug efflux pumps, dysregulation of genes and interactions in tumor microenvironment, tumor cells can develop resistance to CP chemotherapy. The current review focuses on the CP resistance emergence in GC cells with emphasizing on molecular pathways, pharmacological compounds for reversing chemoresistance and the role of nanostructures. Changes in cell death mechanisms such as upregulation of pro-survival autophagy can prevent CP-mediated apoptosis that results in drug resistance. Moreover, increase in metastasis via EMT induction induces CP resistance. Dysregulation of molecular pathways such as PTEN, PI3K/Akt, Nrf2 and others result in changes in CP response of GC cells. Non-coding RNAs determine CP response of GC cells and application of pharmacological compounds with activity distinct of CP can result in sensitivity in tumor cells. Due to efficacy of exosomes in transferring bioactive molecules such as RNA and DNA molecules among GC cells, exosomes can also result in CP resistance. One of the newest progresses in overcoming CP resistance in GC is application of nanoplatforms for delivery of CP in GC therapy that they can increase accumulation of CP at tumor site and by suppressing carcinogenic factors and overcoming biological barriers, they increase CP toxicity on cancer cells.

Drug Discovery and Development of miRNA-Based Nucleotide Drugs for Gastrointestinal Cancer

Short non-coding RNAs, miRNAs, play roles in the control of cell growth and differentiation in cancer. Reportedly, the introduction of miRNAs could reduce the biologically malignant behavior of cancer cells, suggesting a possible use as therapeutic reagents. Given that the forced expression of several miRNAs, including miR-302, results in the cellular reprograming of human and mouse cells, which is similar to the effects of the transcription factors Oct4, Sox2, Klf4, and c-Myc, this suggests that the selective introduction of several miRNAs will be able to achieve anti-cancer effects at the epigenetic and metabolic levels. In this review article, we bring together the recent advances made in studies of microRNA-based therapeutic approaches to therapy-resistant cancers, especially in gastrointestinal organs.

MicroRNA: trends in clinical trials of cancer diagnosis and therapy strategies

As a type of short noncoding RNAs, microRNA (miRNA) undoubtedly plays a crucial role in cancer development. Since the discovery of the identity and clinical functions of miRNAs, over the past few decades, the roles of miRNAs in cancer have been actively investigated. Numerous pieces of evidence indicate that miRNAs are pivotal factors in most types of cancer. Recent cancer research focused on miRNAs has identified and characterized a large cohort of miRNAs commonly dysregulated in cancer or exclusively dysregulated in specific types of cancer. These studies have suggested the potential of miRNAs as biomarkers in the diagnosis and prognostication of cancer. Moreover, many of these miRNAs have oncogenic or tumor-suppressive functions. MiRNAs have been the focus of research given their potential clinical applications as therapeutic targets. Currently, various oncology clinical trials using miRNAs in screening, diagnosis, and drug testing are underway. Although clinical trials studying miRNAs in various diseases have been reviewed before, there have been fewer clinical trials related to miRNAs in cancer. Furthermore, updated results of recent preclinical studies and clinical trials of miRNA biomarkers and drugs in cancer are needed. Therefore, this review aims to provide up-to-date information on miRNAs as biomarkers and cancer drugs in clinical trials.

HOX cluster-embedded lncRNAs and epithelial-mesenchymal transition in cancer: Molecular mechanisms and therapeutic opportunities

Although there has been substantial improvement in the treatment modalities, cancer remains the major cause of fatality worldwide. Metastasis, recurrence, and resistance to oncological therapies are the leading causes of cancer mortality. Epithelial-mesenchymal transition (EMT) is a complex biological process that allows cancer cells to undergo morphological transformation into a mesenchymal phenotype to acquire invasive potential. It encompasses reversible and dynamic ontogenesis by neoplastic cells during metastatic dissemination. Hence, understanding the molecular landscape of EMT is imperative to identify a reliable clinical biomarker to combat metastatic spread. Accumulating evidence reveals the role of HOX (homeobox) cluster-embedded long non-coding RNAs (lncRNAs) in EMT and cancer metastasis. They play a crucial role in the induction of EMT, modulating diverse biological targets. The present review emphasizes the involvement of HOX cluster-embedded lncRNAs in EMT as a molecular sponge, chromatin remodeler, signaling regulator, and immune system modulator. Furthermore, the molecular mechanisms behind therapy resistance and the potential use of novel drugs targeting HOX cluster-embedded lncRNAs in the clinical management of distant metastasis will be discussed.

The Emerging Role of Circular RNA Homeodomain Interacting Protein Kinase 3 and Circular RNA 0046367 through Wnt/Beta-Catenin Pathway on the Pathogenesis of Nonalcoholic Steatohepatitis in Egyptian Patients

Background

Non-alcoholic fatty liver disease is a major problem worldwide that needs non-invasive biomarkers for early diagnosis and treatment response assessment. We aimed to assess the correlation between circRNA-HIPK3 and miRNA-29a expression and its role as miRNA-29a sponge, as well as the correlation between circRNA-0046367 and miRNA-34a expression and its role as miRNA-34a sponge and their effect on regulation of the Wnt/β catenin pathway, which may provide a new target for treatment of non-alcoholic steatohepatitis.

Methods

the research was performed on 110 participants: group (I): fifty-five healthy donors served as controls and group (II): fifty-five patients with fatty liver pattern on abdominal ultrasound. Lipid profile and liver functions were assessed. RT-PCR was performed to assess the RNAs: circRNA-HIPK3, circRNA-0046367, miRNA-29a, miRNA-34a and Wnt mRNA gene expression. ELISA was performed to determine β-catenin protein levels.

Results

miRNA-34a and circRNA-HIPK3 expression were significantly greater, while miRNA-29a and circRNA-0046367 expression were significantly less, in patients than in controls. Wnt/β-catenin regulated by miRNA-29a and miRNA-34a showed a significant decrease that leads to its abnormal effect on lipid metabolism.

Conclusions

our results imply that miRNA-29a can be investigated as a target for circRNA-HIPK3, while miRNA-34a can be investigated as a target for circRNA-0046367, and that circRNA-HIPK3 and circRNA-0046367 may have emerging roles that can affect the pathogenesis of nonalcoholic steatohepatitis through the Wnt/β-catenin pathway and thus be used as therapeutic targets for the disease.

Interruption of the long non-coding RNA HOTAIR signaling axis ameliorates chemotherapy-induced cachexia in bladder cancer

BACKGROUND

Cisplatin-based chemotherapy is the first line of treatment for bladder cancer. However, cisplatin induces muscle wasting associated with NF-κB and cancer cachexia. HOTAIR, an oncogenic long non-coding RNA (lncRNA), promotes cancer progression in different cancers. Crosstalk between HOTAIR and NF-κB is documented. Prothymosin α (ProT) plays important roles in cancer progression and inflammation. However, the potential link between HOTAIR, ProT, and cisplatin-induced cancer cachexia remains unexplored. Here, we investigated the contribution of HOTAIR in cisplatin-induced cancer cachexia and dissected the potential signaling cascade involving the epidermal growth factor receptor (EGFR), ProT, NF-κB, and HOTAIR.

MATERIALS AND METHODS

Expression of ProT and HOTAIR transcripts and their correlations in tumor tissues of bladder cancer patients and bladder cancer cell lines were determined by RT-qPCR. Next, levels of phospho-EGFR, EGFR, phospho-NF-κB, and NF-κB were examined by immunoblot analysis in human bladder cancer cells treated with cisplatin. Expression of HOTAIR in cisplatin-treated cells was also assessed by RT-qPCR. Pharmacological inhibitors and overexpression and knockdown approaches were exploited to decipher the signaling pathway. The murine C2C12 myoblasts were used as an in vitro muscle atrophy model. The syngeneic murine MBT-2 bladder tumor was used to investigate the role of mouse Hotair in cisplatin-induced cancer cachexia.

RESULTS

Expression of ProT and HOTAIR was higher in bladder tumors than in normal adjacent tissues. There were positive correlations between ProT and HOTAIR expression in clinical bladder tumors and bladder cancer cell lines. Cisplatin treatment increased EGFR and NF-κB activation and upregulated ProT and HOTAIR expression in bladder cancer cells. ProT overexpression increased, whereas ProT knockdown decreased, HOTAIR expression. Notably, cisplatin-induced HOTAIR upregulation was abrogated by EGFR inhibitors or ProT knockdown. ProT-induced HOTAIR overexpression was diminished by NF-κB inhibitors. HOTAIR overexpression enhanced, whereas its knockdown reduced, cell proliferation, cachexia-associated pro-inflammatory cytokine expression, and muscle atrophy. Cachexia-associated symptoms were ameliorated in mice bearing Hotair-knockdown bladder tumors undergoing cisplatin treatment.

CONCLUSIONS

We demonstrate for the first time a critical role for HOTAIR and identify the involvement of the EGFR-ProT-NF-κB-HOTAIR signaling axis in cisplatin-induced cachexia in bladder cancer and likely other cancers. Our findings also provide therapeutic targets for this disease.

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.

Emerging roles of long noncoding RNAs in chemoresistance of pancreatic cancer

Pancreatic cancer is one of the most common causes of cancer death in the world due to the lack of early symptoms, metastasis occurrence and chemoresistance. Therefore, early diagnosis by detection of biomarkers, blockade of metastasis, and overcoming chemoresistance are the effective strategies to improve the survival of pancreatic cancer patients. Accumulating evidence has revealed that long noncoding RNA (lncRNA) and circular RNAs (circRNAs) play essential roles in modulating chemosensitivity in pancreatic cancer. In this review article, we will summarize the role of lncRNAs in drug resistance of pancreatic cancer cells, including HOTTIP, HOTAIR, PVT1, linc-ROR, GAS5, UCA1, DYNC2H1-4, MEG3, TUG1, HOST2, HCP5, SLC7A11-AS1 and CASC2. We also highlight the function of circRNAs, such as circHIPK3 and circ_0000284, in regulation of drug sensitivity of pancreatic cancer cells. Moreover, we describe a number of compounds, including curcumin, genistein, resveratrol, quercetin, and salinomycin, which may modulate the expression of lncRNAs and enhance chemosensitivity in pancreatic cancers. Therefore, targeting specific lncRNAs and cicrRNAs could contribute to reverse chemoresistance of pancreatic cancer cells. We hope this review might stimulate the studies of lncRNAs and cicrRNAs, and develop the new therapeutic strategy via modulating these noncoding RNAs to promote chemosensitivity of pancreatic cancer cells.

Long non-coding RNAs (lncRNAs); roles in tumorigenesis and potentials as biomarkers in cancer diagnosis

New research has indicated that long non-coding RNAs (lncRNAs) play critical roles in a broad range of biological processes, including the pathogenesis of many complex human diseases, including cancer. The detailed regulation mechanisms of many lncRNAs in cancer initiation and progression have yet to be discovered, even though a few of lncRNAs' functions in cancer have been characterized. In the present study, we summarize recent advances in the mechanisms and functions of lncRNAs in cancer. We focused on the roles of newly-identified lncRNAs as oncogenes and tumor suppressors, as well as the potential pathways these molecules could play. The paper also discusses their potential uses as biomarkers for the diagnosis and prognosis of cancer.

Functional role of the SLC7A11-AS1/xCT axis in the development of gastric cancer cisplatin-resistance by a GSH-dependent mechanism

Resistance to platinum-based chemotherapy is a major obstacle in gastric cancer (GC) treatment. Abundant long noncoding RNAs (lncRNAs) are reported to play important roles in tumorigenesis and drug resistance biology. Herein, we report that the SLC7A11-AS1 and xCT are involved in cisplatin resistance in GC. SLC7A11-AS1 was downregulated and xCT was upregulated in cisplatin-resistant GC tissues and cell lines. GC patients with low expression of SLC7A11-AS1 and high expression of xCT had a poor prognosis and relatively poor response to chemotherapy. Overexpression of SLC7A11-AS1 weakened GC growth, reduced intracellular GSH biosynthesis, enhanced intracellular reactive oxygen species (ROS) and conferred sensitivity to cisplatin to resistant GC cells in vitro and in vivo. Mechanistically, SLC7A11-AS1 directly suppressed xCT expression, while miR-33a-5p remarkably reduced SLC7A11-AS1 and xCT expression by directly targeting the SLC7A11-AS1 and xCT 3'UTRs. In addition, we found that low SLC7A11-AS1 expression activated the p38MAPK-JNK signaling pathway, and increased the expression of cisplatin export gene ATP7A and the GSH biosynthesis gene GCLM in GC.

Differential Expression of Long Noncoding RNA HOTAIR in Intestinal Metaplasia and Gastric Cancer

INTRODUCTION

High expression of HOTAIR promotes tumor growth and carries a dismal prognosis for the patient. We investigated the prognostic value of HOTAIR expression in gastric cancer (GC) and systematically delineate the expression in relation to Helicobacter pylori infection and preneoplastic changes.

METHODS

HOTAIR expression was analyzed in surgical paired tissue samples of patients with GC and biopsy samples from patients with atrophic gastritis and/or intestinal metaplasia (AG ± -IM), chronic nonatrophic gastritis, and controls. The cancer genome atlas (TCGA) data were used for validation. HOTAIR expression was evaluated in sera and ascites of patients with GC. Quantitative HOTAIR expression analysis was performed using quantitative polymerase chain reaction, and LINE-1 methylation was assessed by bisulfite pyrosequencing.

RESULTS

HOTAIR was more frequently detected in tumor tissues compared with adjacent gastric mucosa (65.4% vs 8.6%). HOTAIR expression was associated with depth of tumor invasion and tumor location and with shorter overall survival in patients with diffuse-type GC as confirmed in the TCGA cohort. HOTAIR was not detectable in controls but was found in 2.2% of patients with chronic nonatrophic gastritis and 18.3% of patients with AG ± IM, which was further associated with IM, grade of IM, and H. pylori positivity.

DISCUSSION

HOTAIR expression was associated with GC and preneoplastic changes of stomach mucosa. Although HOTAIR expression was strongly linked to IM, HOTAIR expression was only associated with worse prognosis in Lauren diffuse and not intestinal type of GC. Further studies are needed to evaluate the value of HOTAIR as diagnostic and predictive biomarker in IM and translational therapeutic relevance of HOTAIR in diffuse-type GC.

Contribution of MicroRNAs in Chemoresistance to Cisplatin in the Top Five Deadliest Cancer: An Updated Review

Cisplatin (DDP) is a well-known anticancer drug used for the treatment of numerous human cancers in solid organs, including bladder, breast, cervical, head and neck squamous cell, ovarian, among others. Its most important mode of action is the DNA-platinum adducts formation, inducing DNA damage response, silencing or activating several genes to induce apoptosis; these mechanisms result in genetics and epigenetics modifications. The ability of DDP to induce tumor cell death is often challenged by the presence of anti-apoptotic regulators, leading to chemoresistance, wherein many patients who have or will develop DDP-resistance. Cancer cells resist the apoptotic effect of chemotherapy, being a problem that severely restricts the successful results of treatment for many human cancers. In the last 30 years, researchers have discovered there are several types of RNAs, and among the most important are non-coding RNAs (ncRNAs), a class of RNAs that are not involved in protein production, but they are implicated in gene expression regulation, and representing the 98% of the human genome non-translated. Some ncRNAs of great interest are long ncRNAs, circular RNAs, and microRNAs (miRs). Accumulating studies reveal that aberrant miRs expression can affect the development of chemotherapy drug resistance, by modulating the expression of relevant target proteins. Thus, identifying molecular mechanisms underlying chemoresistance development is fundamental for setting strategies to improve the prognosis of patients with different types of cancer. Therefore, this review aimed to identify and summarize miRs that modulate chemoresistance in DDP-resistant in the top five deadliest cancer, both in vitro and in vivo human models.

Noncoding RNAs and hyperthermic intraperitoneal chemotherapy in advanced gastric cancer

Gastric cancer (GC) is one of the most common malignant tumors globally. About 20-30% of patients with gastric cancer show peritoneal implantation metastasis at the first diagnosis. Peritoneal metastasis is responsible for 70% of deaths of patients with advanced gastric cancer. Although there are many ways to treat advanced gastric cancer, the prognosis of patients with recurrence is unsatisfactory. An auxiliary treatment with hyperthermic intraperitoneal chemotherapy (HIPEC), is an internationally recognized recommended treatment for advanced gastric cancer. A series of clinical trials have shown that HIPEC significantly improves the overall survival of patients with cancer. Compared with the cytoreductive surgery (CRS) alone, HIPEC combined with CRS markedly reduced the rate of peritoneal metastasis in patients with ovarian cancer and colorectal cancer. It has been demonstrated that HIPEC alters transcription of many genes by affecting non-coding RNAs, which may contribute to the suppressive effect of HIPEC on the synthesis of nucleic acids and proteins in cancer cells. This paper reviews the recent advances in understanding the role of non-coding RNAs in tumor invasion and metastasis of advanced gastric cancer. We also consider changes in noncoding RNA levels and other molecules in advanced gastric cancer cases treated with HIPEC. We hope that our review will provide a reference for future research on molecular epidemiology and etiology of advanced gastric cancer and promote precise treatment of this malignancy using HIPEC.

Progress of HOTAIR-microRNA in hepatocellular carcinoma

The Hox transcript antisense intergenic RNA (HOTAIR) has been identified as a tumor gene, and its expression in HCC is significantly increased. HOTAIR is associated with the proliferation, invasion, metastasis and poor prognosis of HCC. In addition, HOTAIR can also regulate the expression and function of microRNA by recruiting the polycomb repressive complex 2 (PRC2) and competitive adsorption, thus promoting the occurrence and development of HCC. In this review, we discussed the two mechanisms of HOTAIR regulating miRNA through direct binding miRNA and indirect regulation, and emphasized the role of HOTAIR in HCC through miRNA, explained the regulatory pathway of HOTAIR-miRNA-mRNA and introduced the role of this pathway in HCC proliferation, drug resistance, invasion and metastasis.

Long Non-Coding RNA in Gastric Cancer: Mechanisms and Clinical Implications for Drug Resistance

Gastric cancer (GC) is the third leading cause of cancer-related deaths worldwide, with high recurrence and mortality rate. Chemotherapy, including 5-fluorouracil (5-FU), adriamycin (ADR), vincristine (VCR), paclitaxel (PTX), and platinum drugs, remains one of the fundamental methods of GC treatment and has efficiently improved patients’ prognosis. However, most patients eventually develop resistance to chemotherapeutic agents, leading to the failure of clinical treatment and patients’ death. Recent studies suggest that long non-coding RNAs (lncRNAs) are involved in the drug resistance of GC by modulating the expression of drug resistance-related genes via sponging microRNAs (miRNAs). Moreover, lncRNAs also play crucial roles in GC drug resistance via a variety of mechanisms, such as the regulation of the oncogenic signaling pathways, inhibition of apoptosis, induction of autophagy, modulation of cancer stem cells (CSCs), and promotion of the epithelial-to-mesenchymal transition (EMT) process. Some of lncRNAs exhibit great potential as diagnostic and prognostic biomarkers, as well as therapeutic targets for GC patients. Therefore, understanding the role of lncRNAs and their mechanisms in GC drug resistance may provide us with novel insights for developing strategies for individual diagnosis and therapy. In this review, we summarize the recent findings on the mechanisms underlying GC drug resistance regulated by lncRNAs. We also discuss the potential clinical applications of lncRNAs as biomarkers and therapeutic targets in GC.

Gastric cancer: An epigenetic view

Gastric cancer (GC) poses a serious threat worldwide with unfavorable prognosis mainly due to late diagnosis and limited therapies. Therefore, precise molecular classification and search for potential targets are required for diagnosis and treatment, as GC is complicated and heterogeneous in nature. Accumulating evidence indicates that epigenetics plays a vital role in gastric carcinogenesis and progression, including histone modifications, DNA methylation and non-coding RNAs. Epigenetic biomarkers and drugs are currently under intensive evaluations to ensure efficient clinical utility in GC. In this review, key epigenetic alterations and related functions and mechanisms are summarized in GC. We focus on integration of existing epigenetic findings in GC for the bench-to-bedside translation of some pivotal epigenetic alterations into clinical practice and also describe the vacant field waiting for investigation.

The Molecular Roles and Clinical Implications of Non-Coding RNAs in Gastric Cancer

Gastric cancer (GC) is one of the most common malignancies in the world. It is also the fifth most common cancer in China. In recent years, a large number of studies have proved that non-coding RNAs (ncRNAs) can regulate cell proliferation, invasion, metastasis, apoptosis, and angiogenesis. NcRNAs also influence the therapeutic resistance of gastric cancer. NcRNAs mainly consist of miRNAs, lncRNAs and circRNAs. In this paper, we summarized ncRNAs as biomarkers and therapeutic targets for gastric cancer, and also reviewed their role in clinical trials and diagnosis. We sum up different ncRNAs and related moleculars and signaling pathway in gastric cancer, like Bcl-2, PTEN, Wnt signaling. In addition, the potential clinical application of ncRNAs in overcoming chemotherapy and radiotherapy resistance in GC in the future were also focused on.

The role of non-coding RNAs in chemotherapy for gastrointestinal cancers

Gastrointestinal (GI) cancers, including colorectal, gastric, hepatic, esophageal, and pancreatic tumors, are responsible for large numbers of deaths around the world. Chemotherapy is the most common approach used to treat advanced GI cancer. However, chemoresistance has emerged as a critical challenge that prevents successful tumor elimination, leading to metastasis and recurrence. Chemoresistance mechanisms are complex, and many factors and pathways are involved. Among these factors, non-coding RNAs (ncRNAs) are critical regulators of GI tumor development and subsequently can induce resistance to chemotherapy. This occurs because ncRNAs can target multiple signaling pathways, affect downstream genes, and modulate proliferation, apoptosis, tumor cell migration, and autophagy. ncRNAs can also induce cancer stem cell features and affect the epithelial-mesenchymal transition. Thus, ncRNAs could possibly act as new targets in chemotherapy combinations to treat GI cancer and to predict treatment response.

Non-Coding RNAs in Gastric Cancer: From Malignant Hallmarks to Clinical Applications

Gastric cancer (GC) is one of the most lethal malignancies worldwide. However, the molecular mechanisms underlying gastric carcinogenesis remain largely unknown. Over the past decades, advances in RNA-sequencing techniques have greatly facilitated the identification of various non-coding RNAs (ncRNAs) in cancer cells, including microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs). Accumulating evidence has revealed that ncRNAs are essential regulators in GC occurrence and development. However, ncRNAs represent an emerging field of cancer research, and their complex functionality remains to be clarified. Considering the lack of viable biomarkers and therapeutic targets in GC, further studies should focus on elucidating the intricate relationships between ncRNAs and GC, which can be translated into clinical practice. In this review, we summarize recent research progress on how ncRNAs modulate the malignant hallmarks of GC, especially in tumor immune escape, drug resistance, and stemness. We also discuss the promising applications of ncRNAs as diagnostic biomarkers and therapeutic targets in GC, aiming to validate their practical value for clinical treatment.

LncRNA HLA Complex Group 11 Knockdown Alleviates Cisplatin Resistance in Gastric Cancer by Targeting the miR-144-3p/UBE2D1 Axis

OBJECTIVE

Cisplatin (DDP) treatment is one of the most predominant chemotherapeutic strategies for patients with gastric cancer (GC). LncRNA noncoding RNA HLA complex group 11 (lncRNA HCG11) has been confirmed to promote GC progression. This study attempted to investigate the underlying molecular mechanism of HCG11 in DDP resistance of GC.

METHODS

qRT-PCR was performed to evaluate the expression of HCG11, microRNA-144-3p (miR-144-3p), and ubiquitin-conjugating enzyme E2 D1 (UBE2D1) in GC. The correlation between HCG11 and clinicopathological features of GC patients was assessed. DDP-resistant GC cells and their parental cells were cultured in different concentrations of DDP. The role of HCG11 for the viability and the half maximal inhibitory concentration (IC50) of DDP in DDP-resistant GC cells was determined by MTT assay. Then, the invasion of DDP-resistant GC cells was measured by transwell assay. Next, a dual-luciferase reporter assay was used to confirm the interactions among HCG11, miR-144-3p, and UBE2D1 in GC.

RESULTS

The expression of HCG11 and UBE2D1 was elevated in tumor tissues of GC patients, but miR-144-3p was declined. HCG11 expression was elevated in DDP-resistant GC patients and is strongly correlated with DDP sensitivity and World Health Organization grade in GC patients. HCG11 knockdown reduced the viability, IC50 of DDP, and invasion of DDP-resistant GC cells. Additionally, HCG11 targeted miR-144-3p and miR-144-3p further targeted UBE2D1. Feedback experiments indicated that low expression of miR-144-3p or overexpression of UBE2D1 mitigated the inhibitory effect of HCG11 depletion on DDP resistance of GC cells.

CONCLUSION

HCG11 knockdown attenuated DDP resistance of GC cells through via miR-144-3p/UBE2D1 axis, affording a novel therapeutic strategy for GC.

HOTAIR promotes gefitinib resistance through modification of EZH2 and silencing p16 and p21 in non-small cell lung cancer

The long non-coding RNA Hox transcript antisense intergenic RNA (HOTAIR) plays a critical role in tumorigenesis as well as drug resistance in various cancers. However, the molecular mechanism by which HOTAIR induces gefitinib resistance in non-small cell lung cancer is to date unclear. In the present study, we revealed that HOTAIR is upregulated in gefitinib-resistant lung cancer cells and over-expression of HOTAIR enhances gefitinib resistance in lung cancer cells. In addition, the overexpression of HOTAIR promotes cell cycle progression through epigenetic regulation of EZH2/H3K27. Silencing of EZH2 by either siRNA or inhibitors sensitized the lung cancer cells to gefitinib. Inhibition of EZH2 induces expression of p16 and p21, whereas levels of CDK4, cyclinD1, E2F1, and LSD1 are significantly decreased in PC-9 cells overexpressing HOTAIR. ChIP-PCR experiments indicate that HOTAIR increases H3K27me3 recruitment to the promoter of p16 and p21 in PC-9 lung cancer cells overexpressing HOTAIR. In xenograft mouse models, overexpressing HOTAIR in lung cancer tissues decreased p16 and p21 proteins. Taken together, these data suggest that HOTAIR contributes to gefitinib resistance by regulating EZH2 and p16 and p21. Targeting HOTAIR may be a novel therapeutic strategy for treating gefitinib-resistance in non-small cell lung cancer.

LncRNA HOTAIR: A Potential Prognostic Factor and Therapeutic Target in Human Cancers

Long non-coding RNAs (lncRNAs) are emerging as crucial regulators of gene expression and physiological processes. LncRNAs are a class of ncRNAs of 200 nucleotides in length. HOX transcript antisense RNA (HOTAIR), a trans-acting lncRNA with regulatory function on transcription, can repress gene expression by recruiting chromatin modifiers. HOTAIR is an oncogenic lncRNA, and numerous studies have determined that HOTAIR is highly upregulated in a wide variety of human cancers. In this review, we briefly summarize the impact of lncRNA HOTAIR expression and functions on different human solid tumors, and emphasize the potential of HOTAIR on tumor prognosis and therapy. Here, we review the recent studies that highlight the prognostic potential of HOTAIR in drug resistance and survival, and the progress of therapies developed to target HOTAIR to date. Furthermore, targeting HOTAIR results in the suppression of HOTAIR expression or function. Thus, HOTAIR knockdown exhibits great therapeutic potential in various cancers, indicating that targeting lncRNA HOTAIR may serve as a promising strategy for cancer therapy. We also propose that preclinical studies involving HOTAIR are required to provide a better understanding of the exact molecular mechanisms underlying the dysregulation of its expression and function in different human cancers and to explore effective methods of targeting HOTAIR and engineering efficient and targeted drug delivery methods in vivo.

Roles of ncRNAs as ceRNAs in Gastric Cancer

Although ignored in the past, with the recent deepening of research, significant progress has been made in the field of non-coding RNAs (ncRNAs). Accumulating evidence has revealed that microRNA (miRNA) response elements regulate RNA. Long ncRNAs, circular RNAs, pseudogenes, miRNAs, and messenger RNAs (mRNAs) form a competitive endogenous RNA (ceRNA) network that plays an essential role in cancer and cardiovascular, neurodegenerative, and autoimmune diseases. Gastric cancer (GC) is one of the most common cancers, with a high degree of malignancy. Considerable progress has been made in understanding the molecular mechanism and treatment of GC, but GC’s mortality rate is still high. Studies have shown a complex ceRNA crosstalk mechanism in GC. lncRNAs, circRNAs, and pseudogenes can interact with miRNAs to affect mRNA transcription. The study of the involvement of ceRNA in GC could improve our understanding of GC and lead to the identification of potential effective therapeutic targets. The research strategy for ceRNA is mainly to screen the different miRNAs, lncRNAs, circRNAs, pseudogenes, and mRNAs in each sample through microarray or sequencing technology, predict the ceRNA regulatory network, and, finally, conduct functional research on ceRNA. In this review, we briefly discuss the proposal and development of the ceRNA hypothesis and the biological function and principle of ceRNAs in GC, and briefly introduce the role of ncRNAs in the GC’s ceRNA network.

Attacking the PI3K/Akt/mTOR signaling pathway for targeted therapeutic treatment in human cancer

Cancer is the second leading cause of human death globally. PI3K/Akt/mTOR signaling is one of the most frequently dysregulated signaling pathways observed in cancer patients that plays crucial roles in promoting tumor initiation, progression and therapy responses. This is largely due to that PI3K/Akt/mTOR signaling is indispensable for many cellular biological processes, including cell growth, metastasis, survival, metabolism, and others. As such, small molecule inhibitors targeting major kinase components of the PI3K/Akt/mTOR signaling pathway have drawn extensive attention and been developed and evaluated in preclinical models and clinical trials. Targeting a single kinase component within this signaling usually causes growth arrest rather than apoptosis associated with toxicity-induced adverse effects in patients. Combination therapies including PI3K/Akt/mTOR inhibitors show improved patient response and clinical outcome, albeit developed resistance has been reported. In this review, we focus on revealing the mechanisms leading to the hyperactivation of PI3K/Akt/mTOR signaling in cancer and summarizing efforts for developing PI3K/Akt/mTOR inhibitors as either mono-therapy or combination therapy in different cancer settings. We hope that this review will facilitate further understanding of the regulatory mechanisms governing dysregulation of PI3K/Akt/mTOR oncogenic signaling in cancer and provide insights into possible future directions for targeted therapeutic regimen for cancer treatment, by developing new agents, drug delivery systems, or combination regimen to target the PI3K/Akt/mTOR signaling pathway. This information will also provide effective patient stratification strategy to improve the patient response and clinical outcome for cancer patients with deregulated PI3K/Akt/mTOR signaling.

Disruption of Wnt/β-catenin Pathway Elevates the Sensitivity of Gastric Cancer Cells to PD-1 Antibody

BACKGROUND

Gastric cancer (GC) is the fifth most common malignancy tumor and the third cause of cancer-related death around the world. Immune checkpoint inhibitors (ICIs) such as programmed cell death-1 (PD-1) antibodies play an active role in tumor therapy. A recent study reveals that the Wnt/β-catenin signaling pathway is negatively correlated with T-cell infiltration in the tumor microenvironment (TME), thereby influencing the therapeutic efficacy of the PD-1 antibody.

OBJECTIVE

In this study, we aimed to uncover the relationship of the Wnt/β-catenin pathway to CD8+ T cell activity as well as its effect on anti-PD-1 therapeutic efficacy in GC.

METHODS

We first collected clinical samples and went through an immunohistochemical analysis and found that a high β-catenin expression in GC tissues was often associated with a significant absence of CD8+ T-cell infiltration.

RESULTS

In addition, our data further indicated that disruption of the Wnt/β-catenin pathway in GC cells inhibited their migratory and invasive ability. Meanwhile, enhanced sensitivity of GC cells to PD-1 blockade therapy was evident by decreased Jurkat cell apoptosis rate and increased GC cell apoptosis rate in a tumor and Jurkat cells co-culture system with the presence of Wnt/β-catenin pathway inhibition.

CONCLUSION

Collectively, these findings indicated that the Wnt/β-catenin pathway might play a significant role in modulating the activity of Jurkat cells, and downregulation of Wnt/β-catenin may enhance the sensitivity of GC cells to PD-1 antibody in vitro. This result further indicated that β-catenin and PD-1 targeted inhibition might become a potential and effective therapy for GC patients.

MicroRNAs as the critical regulators of cisplatin resistance in gastric tumor cells

Combined chemotherapeutic treatment is the method of choice for advanced and metastatic gastric tumors. However, resistance to chemotherapeutic agents is one of the main challenges for the efficient gastric cancer (GC) treatment. Cisplatin (CDDP) is used as an important regimen of chemotherapy for GC which induces cytotoxicity by interfering with DNA replication in cancer cells and inducing their apoptosis. Majority of patients experience cisplatin-resistance which is correlated with tumor metastasis and relapse. Moreover, prolonged and high-dose cisplatin administrations cause serious side effects such as nephrotoxicity, ototoxicity, and anemia. Since, there is a high rate of recurrence after CDDP treatment in GC patients; it is required to clarify the molecular mechanisms associated with CDDP resistance to introduce novel therapeutic methods. There are various cell and molecular processes associated with multidrug resistance (MDR) including drug efflux, detoxification, DNA repair ability, apoptosis alteration, signaling pathways, and epithelial-mesenchymal transition (EMT). MicroRNAs are a class of endogenous non-coding RNAs involved in chemo resistance of GC cells through regulation of all of the MDR mechanisms. In present review we have summarized all of the miRNAs associated with cisplatin resistance based on their target genes and molecular mechanisms in gastric tumor cells. This review paves the way of introducing a miRNA-based panel of prognostic markers to improve the efficacy of chemotherapy and clinical outcomes in GC patients. It was observed that miRNAs are mainly involved in cisplatin response of gastric tumor cells via regulation of signaling pathways, autophagy, and apoptosis.

Long non-coding RNAs regulating multiple proliferative pathways in cancer cell

Long non-coding RNAs (lncRNAs) belong to an extremely heterogeneous class of non-coding RNAs with a length ranging from 200 to 100,000 bp. They modulate a series of cellular pathways in both physiological and pathological context. It is no coincidence that they are expressed in an aberrant way in pathologies such as cancer, so as to deserve to be subclassified as oncogenes or tumor suppressors. These molecules are also involved in the regulation of cancer cell proliferation. Several lncRNAs are able to modulate cell growth both positively and negatively, and in this review we have focused on a small group of them, characterized by the simultaneous action on different pathways regulating cell proliferation. They have been considered in the light of their behavior in three different subtypes of proliferative pathways that we can define as (I) tumor suppressor, (II) oncogenic and (III) transcriptionally-driven. More specifically, we have characterized some lncRNAs considered oncogenes (such as H19, linc-ROR, MALAT1, HULC, HOTAIR and ANRIL), tumor suppressors (such as MEG3 and lincRNA-p21), and both oncogenes/tumor suppressors (UCA1 and TUG1) in a little more detail. As can be understood from the review, the interactions between lncRNAs and their molecular targets, only in the context of controlling cell proliferation, give rise to an intricate molecular network, the understanding of which, in the future, will certainly be of help for the treatment of molecular diseases such as cancer.