Circular RNA circVAPA promotes chemotherapy drug resistance in gastric cancer progression by regulating miR-125b-5p/STAT3 axis

Helicobacter pylori induce circ_0046854 to regulate microRNA-511-3p/CSF1 axis and enhance the resistance of gastric cancer to cisplatin

Helicobacter pylori (HP) is considered a major risk factor for gastric cancer (GC) and during this process, cytotoxin‑associated gene A (CagA) plays in essence. The study mainly focused on the molecular mechanism of circular RNA 0046854 (circ_0046854) in HP-induced GC. Clinically, 56 cases of GC and normal tissues were collected, and the GC tissues were divided into HP-negative GC tissues (HP-) and 33 HP-positive GC tissues (HP+). Tissue expression of circ_0046854, microRNA (miR)-511-3p and colony-stimulating factor 1 (CSF1) was tested. BGC-823/Cisplatin (DDP) resistant strain was induced and cell growth and DDP resistance were detected after HP infection. In vivo experiments were performed using a mouse xenograft model. The relationship between circ_0046854, miR-511-3p and CSF1 was confirmed. GC tissues especially HP+ cancer tissues expressed high circ_0046854 and CSF1 and low miR-511-3p. HP-induced circ_0046854 expression in GC cells through CagA. Inhibition of circ_0046854 or miR-511-3p elevation inhibited the growth and DDP resistance in GC cells. Circ_0046854 acted as a sponge for miR-511-3p, which targeted CSF1. Restoring CSF1 could abolish the inhibitory effect of miR-511-3p overexpression on CagA+ HP-induced GC progression in vitro. Circ_0046854 silencing repressed tumor growth and aggrandized the inhibiting effects of DDP on tumorigenesis in vivo. Circ_0046854/miR-511-3p/CSF1 axis may be involved in the development of HP-induced GC, thus providing new ideas for studying the mechanism of HP-related gastric diseases.

Induction, growth, drug resistance, and metastasis: A comprehensive summary of the relationship between STAT3 and gastric cancer

Gastric cancer is a prevalent and highly lethal malignancy that poses substantial challenges to healthcare systems globally. Owing to its often asymptomatic nature in early stages, diagnosis frequently occurs at advanced stages when surgical intervention is no longer a viable option, forcing most patients to rely on nonsurgical treatments such as chemotherapy, targeted therapies, and emerging immunotherapies. Unfortunately, the therapeutic response rates for these treatments are suboptimal, and even among responders, the eventual development of drug resistance remains a significant clinical hurdle. Signal transducer and activator of transcription 3 (STAT3) is a widely expressed cellular protein that plays crucial roles in regulating cellular processes such as growth, metabolism, and immune function. Aberrant activation of the STAT3 pathway has been implicated in the initiation, progression, and therapeutic resistance of several cancers, with gastric cancer being particularly affected. Dysregulated STAT3 signaling not only drives tumorigenesis but also facilitates the development of resistance to chemotherapy and targeted therapies, as well as promotes metastatic dissemination. In this study, we explored the critical role of the STAT3 signaling cascade in the pathogenesis of gastric cancer, its contribution to drug resistance, and its involvement in the metastatic process. Furthermore, we assess recent advances in the development of STAT3 inhibitors and their potential application as therapeutic agents in the treatment of gastric cancer. This work provides a comprehensive overview of the current understanding of STAT3 in gastric cancer and offers a foundation for future research aimed at improving therapeutic outcomes in this challenging disease.

Novel role of circRNAs in the drug resistance of gastric cancer: regulatory mechanisms and future for cancer therapy

Cancer, including gastric cancer, has become a serious disease that jeopardizes public life. Currently, the main treatment methods are surgery, radiation therapy, and chemotherapy. One of the primary causes of death for patients with gastric cancer is drug resistance. Several mechanisms of anticancer drugs resistance have been reported, including changes in drugs transport and metabolism, mutations in drug targets, changes in DNA repair systems, inhibition of cell apoptosis and autophagy, gastric cancer stem cells, invasion and migration. It is becoming more widely known that non-coding RNAs, like circRNAs, play a critical role in the resistance of drugs used to treat gastric cancer. CircRNAs have a unique structure and function that is related to gastric cancer resistance, cell proliferation, apoptosis, autophagy, DNA repair systems, migration, and invasion. A clear understanding of the molecular mechanism of circRNAs mediated the resistance of gastric cancer drugs will open a new window for the treatment and management of gastric cancer. Therefore, in this review, we will summarize the current mechanism of drug resistance, and finally discuss the molecular mechanism of circRNAs in regulating the development of drug resistance in gastric cancer.

Crosstalk between circular RNAs and the STAT3 signaling pathway in human cancer

Circular RNAs (circRNAs) are endogenous covalently closed single-stranded RNAs produced by reverse splicing of pre-mRNA. Emerging evidence suggests that circRNAs contribute to cancer progression by modulating the oncogenic STAT3 signaling pathway, which plays key roles in human malignancies. STAT3 signaling-related circRNAs expression appears to be extensively dysregulated in diverse cancer types, where they function either as tumor suppressors or oncogenes. However, the biological effects of STAT3 signaling-related circRNAs and their associations with cancer have not been systematically studied before. Given this, shedding light on the interaction between circRNAs and STAT3 signaling pathway in human malignancies may provide several novel insights into cancer therapy. In this review, we provide a comprehensive introduction to the molecular mechanisms by which circRNAs regulate STAT3 signaling in cancer progression, and the crosstalk between STAT3 signaling-related circRNAs and other signaling pathways. We also further discuss the role of the circRNA/STAT3 axis in cancer chemotherapy sensitivity.

CircUBA2 promotes the cancer stem cell-like properties of gastric cancer through upregulating STC1 via sponging miR-144-5p

BACKGROUND

Cancer stem cells (CSCs) are critical factors that limit the effectiveness of gastric cancer (GC) therapy. Circular RNAs (circRNAs) are confirmed as important regulators of many cancers. However, their role in regulating CSC-like properties of GC remains largely unknown. Our study aimed to investigate the role of circUBA2 in CSC maintenance and the underlying mechanisms.

METHODS

We identified circUBA2 as an upregulated gene using circRNA microarray analysis. qRT-PCR was used to examine the circUBA2 levels in normal and GC tissues. In vitro and in vivo functional assays were performed to validate the role of circUBA2 in proliferation, migration, metastasis and CSC-like properties of GC cell. The relationship between circUBA2, miR-144-5p and STC1 was characterised using bioinformatics analysis, a dual fluorescence reporter system, FISH, and RIP assays.

RESULTS

CircUBA2 expression was significantly increased in GC tissues, and patients with GC with high circUBA2 expression had a poor prognosis. CircUBA2 enhances CSC-like properties of GC, thereby promoting cell proliferation, migration, and metastasis. Mechanistically, circUBA2 promoted GC malignancy and CSC-like properties by acting as a sponge for miR-144-5p to upregulate STC1 expression and further activate the IL-6/JAK2/STAT3 signaling pathway. More importantly, the ability of circUBA2 to enhance CSC-like properties was inhibited by tocilizumab, a humanised Interleukin-6 receptor (IL-6R) antibody. Thus, circUBA2 knockdown and tocilizumab synergistically inhibited CSC-like properties.

CONCLUSIONS

Our study demonstrated the critical role of circUBA2 in regulating CSC-like properties in GC. CircUBA2 may be a promising prognostic biomarker for GC.

CircVDAC3 sequesters microRNA-592 and elevates EIF4E3 expression to inhibit the progression of gastric cancer

BACKGROUND

Accumulating evidence has shown that circular RNAs (circRNAs) are involved in gastric cancer (GC) tumorigenesis. However, specific functional circRNAs in GC remain to be discovered, and their underlying mechanisms remain to be elucidated.

METHODS

CircRNAs that were differentially expressed between GC tissues and controls were analyzed using a circRNA microarray dataset. The expression of circVDAC3 in GC was determined using quantitative real-time PCR (qRT-PCR), and the structural features of circVDAC3 were validated. Cell function assays and animal experiments were conducted to explore the effects of circVDAC3 on GC. Finally, bioinformatics analysis, fluorescent in situ hybridization, and dual luciferase assays were used to analyze the downstream mechanisms of circVDAC3.

RESULTS

Our results showed that circVDAC3 was downregulated in GC and inhibited the proliferation and metastasis of GC cells. Mechanistically, circVDAC3 acts as a competing endogenous RNA (ceRNA) of miR-592 and deregulates the repression of EIF4E3 by miR-592. EIF4E3 is downregulated in GC and overexpression of miR-592 or knockdown of EIF4E3 in circVDAC3-overexpressing cells weakens the anticancer effect of circVDAC3.

CONCLUSION

Our study provides evidence that circVDAC3 affects the growth and metastasis of GC cells via the circVDAC3/miR-592/EIF4E3 axis. Our findings offer valuable insights into the mechanisms underlying GC tumorigenesis and suggest novel therapeutic strategies.

Circular RNAs in the KRAS pathway: Emerging players in cancer progression

Circular RNAs (circRNAs) have been recognized as key components in the intricate regulatory network of the KRAS pathway across various cancers. The KRAS pathway, a central signalling cascade crucial in tumorigenesis, has gained substantial emphasis as a possible therapeutic target. CircRNAs, a subgroup of non-coding RNAs known for their closed circular arrangement, play diverse roles in gene regulation, contributing to the intricate landscape of cancer biology. This review consolidates existing knowledge on circRNAs within the framework of the KRAS pathway, emphasizing their multifaceted functions in cancer progression. Notable circRNAs, such as Circ_GLG1 and circITGA7, have been identified as pivotal regulators in colorectal cancer (CRC), influencing KRAS expression and the Ras signaling pathway. Aside from their significance in gene regulation, circRNAs contribute to immune evasion, apoptosis, and drug tolerance within KRAS-driven cancers, adding complexity to the intricate interplay. While our comprehension of circRNAs in the KRAS pathway is evolving, challenges such as the diverse landscape of KRAS mutant tumors and the necessity for synergistic combination therapies persist. Integrating cutting-edge technologies, including deep learning-based prediction methods, holds the potential for unveiling disease-associated circRNAs and identifying novel therapeutic targets. Sustained research efforts are crucial to comprehensively unravel the molecular mechanisms governing the intricate interplay between circRNAs and the KRAS pathway, offering insights that could potentially revolutionize cancer diagnostics and treatment strategies.

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

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

Unrevealing the vital role of ncRNAs in Gastric Cancer chemoresistance

The high incidence of gastric cancer in many nations and poor overall survival rates has remained a serious global health concern. Chemoresistance in gastric cancer is a significant issue that hinders the efficacy of available treatment options. In gastric cancer, non-coding RNAs like microRNAs, long non-coding RNAs, and circular RNAs have become effective regulators of chemoresistance. These non-coding RNAs can influence several mechanisms, including drug efflux transporters, drug metabolism, and detoxification, cancer stem cells and the epithelial-mesenchymal transition, autophagy and apoptosis, and the tumor microenvironment. In this article review, we summarize the key roles non-coding RNAs play in the chemoresistance of gastric cancer and consider how they might be used in clinical settings as markers for diagnosis and prognosis, as well as potential targets and treatment plans. We also emphasize the need for additional study and collaborations in this area and highlight the difficulties and opportunities in non-coding RNA research for gastric cancer chemoresistance. This review offers crucial insights into the intricate relationship between non-coding RNAs and chemoresistance in gastric cancer, with implications for precision oncology and personalized medicine.

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.

METTL3 promotes drug resistance to oxaliplatin in gastric cancer cells through DNA repair pathway

Gastric cancer (GC) poses a significant threat to human health and remains a prevalent form of cancer. Despite clinical treatments, the prognosis for Gastric cancer patients is still unsatisfactory, largely due to the development of multidrug resistance. Oxaliplatin (OXA), a second-generation platinum drug, is commonly recommended for adjuvant and palliative chemotherapy in Gastric cancer; however, the underlying mechanisms of acquired resistance to Oxaliplatin in Gastric cancer patients are not yet fully understood. In this study, we aimed to explore the potential mechanisms of Oxaliplatin resistance in Gastric cancer by employing bioinformatics analysis and conducting in vitro experiments. Specifically, we focused on investigating the role of methyltransferase-like 3 (METTL3). Our findings revealed that the knockdown of METTL3 significantly impeded the proliferation and migration of Gastric cancer cells. METTL3 knockdown induced apoptosis in OXA-resistant Gastric cancer cells and enhanced their sensitivity to Oxaliplatin. Furthermore, we found that DNA repair pathways were significantly activated in OXA-resistant Gastric cancer cells, and METTL3 knockdown significantly inhibited DNA repair pathways. Another important finding is that METTL3 knockdown and OXA-induced Gastric cancer cell death are additive, and the targeted METTL3 can assist Oxaliplatin treatment. Collectively, our findings suggest that METTL3 knockdown can augment the sensitivity of Gastric cancer cells to Oxaliplatin by impeding DNA repair processes. Consequently, targeting METTL3 holds great promise as a viable adjuvant strategy in the treatment of Gastric cancer patients.

Noncoding RNAs as regulators of STAT3 pathway in gastrointestinal cancers: Roles in cancer progression and therapeutic response

Gastrointestinal (GI) tumors (cancers of the esophagus, gastric, liver, pancreas, colon, and rectum) contribute to a large number of deaths worldwide. STAT3 is an oncogenic transcription factor that promotes the transcription of genes associated with proliferation, antiapoptosis, survival, and metastasis. STAT3 is overactivated in many human malignancies including GI tumors which accelerates tumor progression, metastasis, and drug resistance. Research in recent years demonstrated that noncoding RNAs (ncRNAs) play a major role in the regulation of many signaling pathways including the STAT3 pathway. The major types of endogenous ncRNAs that are being extensively studied in oncology are microRNAs, long noncoding RNAs, and circular RNAs. These ncRNAs can either be tumor-promoters or tumor-suppressors and each one of them imparts their activity via different mechanisms. The STAT3 pathway is also tightly modulated by ncRNAs. In this article, we have elaborated on the tumor-promoting role of STAT3 signaling in GI tumors. Subsequently, we have comprehensively discussed the oncogenic as well as tumor suppressor functions and mechanism of action of ncRNAs that are known to modulate STAT3 signaling in GI cancers.

The role of microRNAs in the different phases of liver regeneration

INTRODUCTION

Since the first discovery of microRNAs (miRs) extensive evidence reveals their indispensable role in different patho-physiological processes. They are recognized as critical regulators of hepatic regeneration, as they modulate multiple complex signaling pathways affecting liver regeneration. MiR-related translational suppression and degradation of target mRNAs and proteins are not limited to one specific gene, but act on multiple targets.

AREAS COVERED

In this review, we are going to explore the role of miRs in the context of liver regeneration and discuss the regulatory effects attributed to specific miRs. Moreover, specific pathways crucial for liver regeneration will be discussed, with a particular emphasis on the involvement of miRs within the respective signaling cascades.

EXPERT OPINION

The considerable amount of studies exploring miR functions in a variety of diseases paved the way for the development of miR-directed therapeutics. Clinical implementation has already shown promising results, but additional research is warranted to assure safe and efficient delivery. Nevertheless, given the broad functional properties of miRs and their critical involvement during hepatic regeneration, they represent an attractive treatment target to promote liver recovery after hepatic resection.

MiR-125b-5p/STAT3 Axis Regulates Drug Resistance in Osteosarcoma Cells by Acting on ABC Transporters

Background

The poor prognosis of the highly malignant tumor osteosarcoma stems from its drug resistance and therefore exploring its resistance mechanisms will help us identify more effective treatment options. However, the effects of miR-125b-5p on drug resistance in osteosarcoma cells are still unclear.

Methods

To study the effects of miR-125b-5p on drug resistance in osteosarcoma cells. Osteosarcoma-resistant miR-125b-5p was obtained from the databases GeneCards and g:Profiler. CCK8, western blot, and transwell were applied for the detection of the miR-125b-5p effects on proliferation, migration, invasion, apoptosis, and drug resistance in osteosarcoma. Bioinformatics is aimed at demonstrating the targeting factor miR-125b-5p, performing protein interaction enrichment analysis by Metascape, and finally validating by binding sites.

Results

Upregulation of miR-125b-5p restrains proliferation, migration, and invasion of osteosarcoma and promotes apoptosis. In addition, miR-125b-5p can restore drug sensitivity in drug-resistant osteosarcoma. miR-125-5p restrains the signal transducer and inhibits the transcription 3 (STAT3) expression activator via targeting its 3'-UTR. STAT3 affects drug-resistant osteosarcoma to regulate the ABC transporter.

Conclusion

miR-125b-5p/STAT3 axis mediates the drug resistance of osteosarcoma by acting on ABC transporter.

The critical role of circular RNAs in drug resistance in gastrointestinal cancers

Nowadays, drug resistance (DR) in gastrointestinal (GI) cancers, as the main reason for cancer-related mortality worldwide, has become a serious problem in the management of patients. Several mechanisms have been proposed for resistance to anticancer drugs, including altered transport and metabolism of drugs, mutation of drug targets, altered DNA repair system, inhibited apoptosis and autophagy, cancer stem cells, tumor heterogeneity, and epithelial-mesenchymal transition. Compelling evidence has revealed that genetic and epigenetic factors are strongly linked to DR. Non-coding RNA (ncRNA) interferences are the most crucial epigenetic alterations explored so far, and among these ncRNAs, circular RNAs (circRNAs) are the most emerging members known to have unique properties. Due to the absence of 5' and 3' ends in these novel RNAs, the two ends are covalently bonded together and are generated from pre-mRNA in a process known as back-splicing, which makes them more stable than other RNAs. As far as the unique structure and function of circRNAs is concerned, they are implicated in proliferation, migration, invasion, angiogenesis, metastasis, and DR. A clear understanding of the molecular mechanisms responsible for circRNAs-mediated DR in the GI cancers will open a new window to the management of GI cancers. Hence, in the present review, we will describe briefly the biogenesis, multiple features, and different biological functions of circRNAs. Then, we will summarize current mechanisms of DR, and finally, discuss molecular mechanisms through which circRNAs regulate DR development in esophageal cancer, pancreatic cancer, gastric cancer, colorectal cancer, and hepatocellular carcinoma.

CircVAPA contributes to hyper-proliferation and inflammation of keratinocytes through miR-125b-5p/sirt6 axis in psoriasis

Psoriasis is an autoimmune skin disease with abnormal keratinocyte hyperproliferation. The important roles of circular RNAs (circRNAs) in various inflammatory diseases have been revealed. The present study aimed to investigate the roles of circVAPA and its molecular mechanisms in psoriasis. Quantitative real-time polymerase chain reaction was performed to measure the RNA expression. Enzyme-linked immunosorbent assays were employed to examine the production of inflammatory factors. Cell-counting kit-8, EDU and flow cytometry assay were conducted to examine the cell viability, proliferation and apoptosis respectively. Dual-luciferase reporter assay and ribonucleoprotein immunoprecipitation (RIP) were conducted to verify the target relationship between miR-125b-5p and circVAPA or Sirt6. Herein our findings showed increased expression of circVAPA and Sirt6 and decreased level of miR-125b-5p in psoriatic lesional tissues and M5-stimulated keratinocytes. Mechanistically, circVAPA knockdown significantly suppressed the promotion of M5 on cell viability, proliferation, and inflammation of HaCaT cells. circVAPA was verified to interact with miR-125b-5p, while inhibition of miR-125b-5p counteracted circVAPA knockdown-mediated effects in M5-stimulated HaCaT cells. Sirt6 was confirmed as a target of miR-125b-5p, and miR-125b-5p overexpression inhibited cell growth and inflammation partly by targeting Sirt6 in M5-stimulated HaCaT cells. Moreover, circVAPA was featured as a competing endogenous RNA by directly sponging miR-125b-5p to up-regulate the expression of Sirt6. CircVAPA participate in the progression of psoriasis through miR-125b-5p/sirt6 axis by regulating proliferation and inflammation of keratinocytes, highlighting a potential therapeutic target for psoriasis.

CircRNA: A new class of targets for gastric cancer drug resistance therapy

Gastric cancer (GC) is one of the most common malignancies worldwide. Patients with advanced GC need palliative care to ensure survival. This includes the use of chemotherapy agents, such as cisplatin, 5-fluorouracil, oxaliplatin, paclitaxel, and pemetrexed, as well as targeted agents. However, the emergence of drug resistance evidence in poor patient outcomes and poor prognosis is a motivation to determine the specific mechanism of drug resistance. Interestingly, circular RNAs (circRNAs) play an important part in the carcinogenesis and progression of GC and are involved in GC drug resistance. This review systematically summarizes the functions and mechanisms of circRNAs underlying GC drug resistance, especially chemoresistance. It also emphasizes that circRNAs can serve as promising targets for improving drug resistance and therapeutic efficacy.

Emerging roles of circular RNAs in gastric cancer metastasis and drug resistance

Gastric cancer (GC) is an aggressive malignancy with a high mortality rate and poor prognosis, primarily caused by metastatic lesions. Improved understanding of GC metastasis at the molecular level yields meaningful insights into potential biomarkers and therapeutic targets. Covalently closed circular RNAs (circRNAs) have emerged as crucial regulators in diverse human cancers including GC. Furthermore, accumulating evidence has demonstrated that circRNAs exhibit the dysregulated patterns in GC and have emerged as crucial regulators in GC invasion and metastasis. However, systematic knowledge regarding the involvement of circRNAs in metastatic GC remains obscure. In this review, we outline the functional circRNAs related to GC metastasis and drug resistance and discuss their underlying mechanisms, providing a comprehensive delineation of circRNA functions on metastatic GC and shedding new light on future therapeutic interventions for GC metastases.

Signaling pathways and therapeutic interventions in gastric cancer

Gastric cancer (GC) ranks fifth in global cancer diagnosis and fourth in cancer-related death. Despite tremendous progress in diagnosis and therapeutic strategies and significant improvements in patient survival, the low malignancy stage is relatively asymptomatic and many GC cases are diagnosed at advanced stages, which leads to unsatisfactory prognosis and high recurrence rates. With the recent advances in genome analysis, biomarkers have been identified that have clinical importance for GC diagnosis, treatment, and prognosis. Modern molecular classifications have uncovered the vital roles that signaling pathways, including EGFR/HER2, p53, PI3K, immune checkpoint pathways, and cell adhesion signaling molecules, play in GC tumorigenesis, progression, metastasis, and therapeutic responsiveness. These biomarkers and molecular classifications open the way for more precise diagnoses and treatments for GC patients. Nevertheless, the relative significance, temporal activation, interaction with GC risk factors, and crosstalk between these signaling pathways in GC are not well understood. Here, we review the regulatory roles of signaling pathways in GC potential biomarkers, and therapeutic targets with an emphasis on recent discoveries. Current therapies, including signaling-based and immunotherapies exploited in the past decade, and the development of treatment for GC, particularly the challenges in developing precision medications, are discussed. These advances provide a direction for the integration of clinical, molecular, and genomic profiles to improve GC diagnosis and treatments.

Prospects of circular RNAs: the regulators of drug resistance and metastasis in gastric cancer

Gastric cancer (GC) is one of the most common malignant tumors. Although there are multiple therapeutic methods, the 5-year survival rate for GC remains low primarily due to metastasis and resistance to chemotherapy. GC treatments, which include chemotherapy drugs, targeted drugs, and immunologic drugs, improve the prognosis of advanced GC patients. Nevertheless, resistance to these drugs may result in treatment failure. Tumor metastasis also plays a key role in tumor progression and limits the clinical efficacy of treatments. Recently, it has been reported that circular RNAs (circRNAs), non-coding RNAs, regulate GC drug resistance and metastasis to improve prognosis. In this review, we summarized systematically the underlying mechanisms of circRNA regulation of gastric neoplasm drug resistance and tumor metastasis. Thus we shed light on the potential of circRNAs to function as potential GC biomarkers and therapeutics.

Extracellular Vesicles Carrying miR-887-3p Promote Breast Cancer Cell Drug Resistance by Targeting BTBD7 and Activating the Notch1/Hes1 Signaling Pathway

Objective

Chemoresistance remains the primary reason threatening the prognosis of breast cancer (BC) patients. Extracellular vesicles (EVs) contribute to chemoresistance by carrying microRNAs (miRNAs). This study investigated the mechanism of miR-887-3p mediated by EVs in BC cell drug resistance.

Methods

MDA-MB-231-derived EVs were extracted and identified. BC cells were treated with different concentrations of doxorubicin, cisplatin, and fulvestrant, and the cell survival was evaluated. PKH26-labeled EVs were cocultured with BC cells, and the uptake of EVs was observed. miR-887-3p expression in BC cells and EVs was detected. After silencing miR-887-3p in MDA-MB-231 cells, BC cells were treated with EV-inhi to observe drug resistance. The target gene of miR-887-3p was predicted and verified. The levels of downstream Notch1/Hes1 pathway were detected. Xenograft experiment was conducted to evaluate the effect of EVs on the growth and drug resistance in vivo.

Results

MDA-MB-231-derived EVs enhanced the drug resistance of BC cells. EVs carried miR-887-3p into BC cells. miR-887-3p expression was elevated in BC cells and EVs. miR-887-3p inhibition reduced the drug resistance of BC cells. miR-887-3p targeted BTBD7. Overexpression of BTBD7 partially reversed the drug resistance of BC cells caused by EV treatment. EV treatment increased the level of Notch1/Hes1, and overexpression of BTBD7 decreased the level of Notch1/Hes1. In vivo experiments further validated the results of in vitro experiments.

Conclusion

EVs carrying miR-887-3p could target BTBD7 and activate the Notch1/Hes1 signaling pathway, thereby promoting BC cell drug resistance. This study may offer novel insights into BC treatment.

Advances in the Study of CircRNAs in Tumor Drug Resistance

Recent studies have revealed that circRNAs can affect tumor DNA damage and repair, apoptosis, proliferation, and invasion and influence the transport of intratumor substances by acting as miRNA sponges and transcriptional regulators and binding to proteins in a variety of ways. However, research on the role of circRNAs in cancer radiotherapy and chemoresistance is still in its early stages. Chemotherapy is a common approach to oncology treatment, but the development of tumor resistance limits the overall clinical efficacy of chemotherapy for cancer patients. The current study suggests that circRNAs have a facilitative or inhibitory effect on the development of resistance to conventional chemotherapy in a variety of tumors, suggesting that circRNAs may serve as a new direction for the study of antitumor drug resistance. In this review, we will briefly discuss the biological features of circRNAs and summarize the recent progression of the involvement of circRNAs in the development and pathogenesis of cancer chemoresistance.

Hsa_circ_0000081 promotes the function of gastric cancer through sponging hsa-miR-423-5p to influence 3-phosphoinositide-dependent kinase 1 expression

Gastric cancer (GC) is one of the most common malignancies in the world, and effective therapeutic targets need to be identified for this type of cancer. In this study, circular RNA (circRNA) microarray analysis was utilized to screen differentially expressed circRNA in GC. Using quantitative reverse transcription polymerase chain reaction (qRT-PCR), hsa_circ_0000081 (circRNA-0000081) expression was found to be up-regulated in tissues and cells and was negative correlated with patients' survival time. RNase R and Actinomycin D assays indicated that circRNA-0000081 was significantly more resistant to R enzyme and had a longer half-life than linear RNA. Moreover, the knockdown or overexpression of circRNA-000081 could influence the proliferation, migration, and invasion potential of GC. Finally, dual luciferase reporter, RNA immunoprecipitation, qRT-PCR, and western blotting assays were used to verify the targeting relationship between circRNA-000081 and miRNA-423-5p or miRNA-423-5p and 3-phosphoinositide-dependent kinase 1 (PDPK1). In conclusion, circRNA-0000081 promotes the function of GC through sponging hsa-miR-423-5p to influence PDPK1 expression, which has a promising therapeutic potential for treating patients with GC.

The Emerging Roles of Circular RNAs in the Chemoresistance of Gastrointestinal Cancer

Gastrointestinal (GI) cancer represents a major global health problem due to its aggressive characteristics and poor prognosis. Despite the progress achieved in the development of treatment regimens, the clinical outcomes and therapeutic responses of patients with GI cancer remain unsatisfactory. Chemoresistance arising throughout the clinical intervention is undoubtedly a critical barrier for the successful treatment of GI cancer. However, the precise mechanisms associated with chemoresistance in GI cancer remain unclear. In the past decade, accumulating evidence has indicated that circular RNAs (circRNAs) play a key role in regulating cancer progression and chemoresistance. Notably, circRNAs function as molecular sponges that sequester microRNAs (miRNAs) and/or proteins, and thus indirectly control the expression of specific genes, which eventually promote or suppress drug resistance in GI cancer. Therefore, circRNAs may represent potential therapeutic targets for overcoming drug resistance in patients with GI cancer. This review comprehensively summarizes the regulatory roles of circRNAs in the development of chemoresistance in different GI cancers, including colorectal cancer, gastric cancer and esophageal cancer, as well as deciphers the underlying mechanisms and key molecules involved. Increasing knowledge of the important functions of circRNAs underlying drug resistance will provide new opportunities for developing efficacious therapeutic strategies against GI cancer.

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.

Propofol induces ferroptosis and inhibits malignant phenotypes of gastric cancer cells by regulating miR-125b-5p/STAT3 axis

BACKGROUND

Gastric cancer is a common malignancy with poor prognosis, in which ferroptosis plays a crucial function in its development. Propofol is a widely used anesthetic and has antitumor potential in gastric cancer. However, the effect of propofol on ferroptosis during gastric cancer progression remains unreported.

AIM

To explore the function of propofol in the regulation of ferroptosis and malignant phenotypes of gastric cancer cells.

METHODS

MTT assays, colony formation assays, Transwell assays, wound healing assay, analysis of apoptosis, ferroptosis measurement, luciferase reporter gene assay, and quantitative reverse transcription polymerase chain reaction were used in this study.

RESULTS

Our data showed that propofol was able to inhibit proliferation and induce apoptosis of gastric cancer cells. Meanwhile, propofol markedly repressed the invasion and migration of gastric cancer cells. Importantly, propofol enhanced the erastin-induced inhibition of growth of gastric cancer cells. Consistently, propofol increased the levels of reactive oxygen species, iron, and Fe²⁺ in gastric cancer cells. Moreover, propofol suppressed signal transducer and activator of transcription (STAT)3 expression by upregulating miR-125b-5p and propofol induced ferroptosis by targeting STAT3 in gastric cancer cells. The miR-125b-5p inhibitor or STAT3 overexpression reversed propofol-attenuated malignant phenotypes of gastric cancer cells.

CONCLUSION

Propofol induced ferroptosis and inhibited malignant phenotypes of gastric cancer cells by regulating the miR-125b-5p/STAT3 axis. Propofol may serve as a potential therapeutic candidate for gastric cancer.

Construction of miRNA-mRNA-TF Regulatory Network for Diagnosis of Gastric Cancer

Gastric cancer (GC), as an epidemic cancer worldwide, has more than 1 million new cases and an estimated 769,000 deaths worldwide in 2020, ranking fifth and fourth in global morbidity and mortality. In mammals, both miRNAs and transcription factors (TFs) play a partial role in gene expression regulation. The mRNA expression profile and miRNA expression profile of GEO database were screened by GEO2R for differentially expressed genes (DEGs) and differentially expressed miRNAs (DEMs). Then, DAVID annotated the functions of DEGs to understand the functions played in biological processes. The prediction of potential target genes of miRNA and key TFs of mRNA was performed by mipathDB V2.0 and CHEA3, respectively, and the gene list comparison was performed to look for overlapping genes coregulated by key TFs and DEMs. Finally, the obtained miRNAs, TF, and overlapping genes were used to construct the miRNA-mRNA-TF regulatory network, which was verified by RT-qPCR. 76 upregulated DEGs, 199 downregulated DEGs, and 3 upregulated miRNAs (miR-199a-3p/miR-199b-3p, miR-125b-5p, and miR-199a-5p) were identified from the expression profiles of mRNA (GSE26899, GSE29998, GSE51575, and GSE13911) and miRNA (GSE93415), respectively. Through database prediction and gene list comparison, it was found that among the 199 downregulated DEGs, 61, 71, and 69 genes were the potential targets of miR-199a-3p/miR-199b-3p, miR-125b-5p, and miR-199a-5p, respectively. 199 downregulated DEGs were used as the gene list for the prediction of key TFs, and the results showed that RFX6 ranked the highest. The potential target overlap genes of miR-199a-3p/miR-199b-3p, miR-125b-5p, and miR-199a-5p were 4 genes (SH3GL2, ATP4B, CTSE, and SORBS2), 7 genes (SLC7A8, RNASE4, ESRRG, PGC, MUC6, Fam3B, and FMO5), and 6 genes (CHGA, PDK4, TMPRSS2, CLIC6, GPX3, and PSCA), respectively. Finally, we constructed a miRNA-mRNA-TF regulatory network based on the above 17 mRNAs, 3 miRNAs, and 1 TF and verified by RT-qPCR and western blot results that the expression of RFX6 was downregulated in GC tissues. These identified miRNAs, mRNAs, and TF have a certain reference value for further exploration of the regulatory mechanism of GC.

Research progress of circRNAs in chemotherapy resistance of digestive system neoplasms

Circular RNAs (circRNAs) are a novel class of noncoding RNA molecules with a unique closed continuous loop structure. CircRNAs are abundant in eukaryotic cells, have unique stability and tissue specificity, and can play a biological regulatory role at various levels, such as transcriptional and posttranscriptional levels. Accumulating evidence indicates that circRNAs play critical roles in tumor genesis, development, and chemotherapy. Chemotherapy is a primary type of intervention for most cancers, but its therapeutic efficacy is usually retarded by intrinsic and acquired resistance. CircRNAs regulate tumor chemoresistance through various molecular mechanisms, such as affecting apoptosis, promoting drug transportation, promoting DNA repair, promoting epithelial-mesenchymal transformation, regulating the characteristics of tumor stem cells, and affecting autophagy. This review summarizes the recent progress and mechanisms of circRNAs in cancer cell resistance to chemotherapy.

Contribution of circRNAs in gastric cancer

Gastric cancer (GC) is one of the most commonly diagnosed neoplasms in the world. A number of environmental and lifestyle factors, particularly chronic infection with Helicobacter pylori, have been found to partake in the pathogenesis of GC. The advent of high-throughput genome and transcriptome analysis has enhanced the knowledge about molecular mechanisms of the pathogenesis of GC. However, data regarding the expression of several circRNAs, such as circLMTK2, are not consistent. We explain the role of circRNAs in the development of GC. We searched databases for the newest publications using the terms gastric cancer and circRNA. Each circRNA alteration, downstream targets, its impacts on cancer cells, and the prognostic and diagnostic roles of these circRNAs have been discussed. Taken together, circRNAs can be putative biomarkers in GC and potential targets for the treatment of this cancer. Yet, this field is still in its infancy and needs further experiments for reaching the clinical application. As these transcripts are stable in circulation, they can be used in non-invasive methods of cancer detection and patients' follow-up.