hsa_circ_0000520 influences herceptin resistance in gastric cancer cells through PI3K-Akt signaling pathway

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.

Exploring the dual role of circRNA and PI3K/AKT pathway in tumors of the digestive system

The interactions among circRNAs, the PI3K/AKT pathway, and their downstream effectors are intricately linked to their functional roles in tumorigenesis. Furthermore, the circRNAs/PI3K/AKT axis has been significantly implicated in the context of digestive system tumors. This axis is frequently abnormally activated in digestive cancers, including gastric cancer, colorectal cancer, pancreatic cancer, and others. Moreover, the overactivation of the circRNAs/PI3K/AKT axis promotes tumor cell proliferation, suppresses apoptosis, enhances invasive and metastatic capabilities, and contributes to drug resistance. In this regard, gaining crucial insights into the complex interaction between circRNAs and the PI3K/AKT pathway holds great potential for elucidating disease mechanisms, identifying diagnostic biomarkers, and designing targeted therapeutic interventions.

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.

circUBAP2 inhibits cisplatin resistance in gastric cancer via miR-300/KAT6B axis

Circular RNAs play an important role in regulating cisplatin (CDDP) resistance in gastric cancer (GC). The aim of this study was to examine the role and downstream regulation mechanisms of circUBAP2 in CDDP resistance of GC. The expression of circUBAP2 in GC and its correlation with the prognosis of GC patients were analyzed using qRT-PCR and the Kaplan-Meier plotter database. The effects of circUBAP2 on cell viability and apoptosis were investigated by Cell Counting Kit 8 assay and flow cytometry. The expressions of drug-resistance-related proteins, P-gp and MRP1, were detected by Western blot. The interaction between circUBAP2 and miR-300 was confirmed using RNA pulldown and immunoprecipitation assays. The correlation between miR-300 and KAT6B was assessed using dual-luciferase reporter assay and TCGA database. CircUBAP2 was downregulated in GC tissues and cell lines, and correlated with the poor prognosis of GC. In addition, circUBAP2 enhanced apoptosis but inhibited cell viability and the CDDP resistance of GC cells in vitro . CircUBAP2 acted as a sponge of microRNA-300 (miR-300) and was negatively correlated with miR-300. Moreover, the upregulation of miR-300 partially removed the effects of circUBAP2 on cell viability, apoptosis and CDDP resistance in GC cells. MiR-300 directly targeted to lysine acetyltransferase 6B (KAT6B), and KAT6B overexpression showed an inhibitory effect on cell viability and CDDP resistance of GC cells. Our data suggested that the circUBAP2/miR-300/KAT6B axis was involved in the inhibition of CDDP resistance in GC, which might provide a novel focus for potential GC therapy.

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.

Non-coding RNA in cancer drug resistance: Underlying mechanisms and clinical applications

Cancer is one of the most frequently diagnosed malignant diseases worldwide, posing a serious, long-term threat to patients’ health and life. Systemic chemotherapy remains the first-line therapeutic approach for recurrent or metastatic cancer patients after surgery, with the potential to effectively extend patient survival. However, the development of drug resistance seriously limits the clinical efficiency of chemotherapy and ultimately results in treatment failure and patient death. A large number of studies have shown that non-coding RNAs (ncRNAs), particularly microRNAs, long non-coding RNAs, and circular RNAs, are widely involved in the regulation of cancer drug resistance. Their dysregulation contributes to the development of cancer drug resistance by modulating the expression of specific target genes involved in cellular apoptosis, autophagy, drug efflux, epithelial-to-mesenchymal transition (EMT), and cancer stem cells (CSCs). Moreover, some ncRNAs also possess great potential as efficient, specific biomarkers in diagnosis and prognosis as well as therapeutic targets in cancer patients. In this review, we summarize the recent findings on the emerging role and underlying mechanisms of ncRNAs involved in cancer drug resistance and focus on their clinical applications as biomarkers and therapeutic targets in cancer treatment. This information will be of great benefit to early diagnosis and prognostic assessments of cancer as well as the development of ncRNA-based therapeutic strategies for cancer patients.

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.

circRNA_101277 Influences Cisplatin Resistance of Colorectal Cancer Cells by Modulating the miR-370/IL-6 Axis

Background. Colorectal cancer (CRC) is among the most prevalent malignancies globally. Early detection of precancerous lesions through routine colonoscopy has led to a dramatic reduction in CRC-related incidence and mortality among those between the ages of 50 and 70. However, in those where the disease progresses to an advanced stage, chemotherapy remains the primary available treatment option, and the associated 5-year survival rate remains low. The identification of genes associated with CRC chemoresistance would thus be a beneficial approach to identifying novel treatments for this deadly disease. Methods. The expression of circRNA_101277, miR-370, and IL-6 was assessed via qRT-PCR. IL-6 levels were measured with a human IL-6 ELISA kit based on the provided protocols. CRC cellular proliferation and cisplatin IC50 values were quantified via MTT assays. Luciferase assays were used to detect circRNA_101277 and miR-370 binding sites or miR-370 and IL-6 binding sites. Results. circRNA_101277 was increased in CRC tissues compared with control samples. circRNA_101277 overexpression was evident in CRC cells, and knockdown of this circRNA suppressed cellular proliferation and cisplatin resistance in these cancer cells. At a mechanistic level, circRNA_101277 was found to function by sequestering miR-370, thereby upregulating the miR-370 target gene IL-6 and promoting cisplatin resistance via this miR-370/IL-6 axis. Conclusion. In summary, our data highlight circRNA_101277 as a novel driver of CRC cell cisplatin resistance that functions by sequestering miR-370 and thereby enhancing IL-6 expression. These findings suggest that this circRNA_101277/miR-370/IL-6 axis may represent a critical axis of chemoresistance in CRC that can be targeted to diagnose and/or treat this cancer.

Identification of Circular RNA-Based Immunomodulatory Networks in Colorectal Cancer

BACKGROUND

Circular RNAs (circRNAs) have been recently proposed as hub molecules in various diseases, especially in tumours. We found that circRNAs derived from ribonuclease P RNA component H1 (RPPH1) were highly expressed in colorectal cancer (CRC) samples from Gene Expression Omnibus (GEO) datasets.

OBJECTIVE

We sought to identify new circRNAs derived from RPPH1 and investigate their regulation of the competing endogenous RNA (ceRNA) and RNA binding protein (RBP) networks of CRC immune infiltration.

METHODS

The circRNA expression profiles miRNA and mRNA data were extracted from the GEO and The Cancer Genome Atlas (TCGA) datasets, respectively. The differentially expressed (DE) RNAs were identified using R software and online server tools, and the circRNA-miRNA-mRNA and circRNA-protein networks were constructed using Cytoscape. The relationship between targeted genes and immune infiltration was identified using the GEPIA2 and TIMER2 online server tools.

RESULTS

A ceRNA network, including eight circRNAs, five miRNAs, and six mRNAs, was revealed. Moreover, a circRNA-protein network, including eight circRNAs and 49 proteins, was established. The targeted genes, ENOX1, NCAM1, SAMD4A, and ZC3H10, are closely related to CRC tumour-infiltrating macrophages.

CONCLUSIONS

We analysed the characteristics of circRNA from RPPH1 as competing for endogenous RNA binding miRNA or protein in CRC macrophage infiltration. The results point towards the development of a new diagnostic and therapeutic paradigm for CRC.

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.

The Role of Circular RNAs in the Drug Resistance of Cancers

Cancer is a major threat to human health and longevity. Chemotherapy is an effective approach to inhibit cancer cell proliferation, but a growing number of cancer patients are prone to develop resistance to various chemotherapeutics, including platinum, paclitaxel, adriamycin, and 5-fluorouracil, among others. Significant progress has been made in the research and development of chemotherapeutic drugs over the last few decades, including targeted therapy drugs and immune checkpoint inhibitors; however, drug resistance still severely limits the application and efficacy of these drugs in cancer treatment. Recently, emerging studies have emphasized the role of circular RNAs (circRNAs) in the proliferation, migration, invasion, and especially chemoresistance of cancer cells by regulating the expression of related miRNAs and targeted genes. In this review, we comprehensively summarized the potential roles and mechanisms of circRNAs in cancer drug resistance including the efflux of drugs, apoptosis, intervention with the TME (tumor microenvironment), autophagy, and dysfunction of DNA damage repair, among others. Furthermore, we highlighted the potential value of circRNAs as new therapeutic targets and prognostic biomarkers for cancer.

Up-Regulation of circEIF6 Contributes to Pancreatic Cancer Development Through Targeting miR-557/SLC7A11/PI3K/AKT Signaling

BACKGROUND

Accruing evidences have pointed out that abnormal expression of circular RNAs (circRNAs) was closely related to the development of many malignancies. The present study intended to disclose the role of circRNA eukaryotic translation initiation factor 6 (circEIF6; hsa_circ_0060055) in pancreatic cancer progression.

METHODS

Quantitative real-time polymerase chain reaction (qRT-PCR) was conducted to determine the expression of circEIF6, EIF6 messenger RNA (mRNA), microRNA-557 (miR-557) and solute carrier family 7 member 11 (SLC7A11) mRNA. Cell proliferation ability, migration and invasion abilities and apoptosis were evaluated by Cell Counting Kit 8 (CCK8) assay, transwell migration and invasion assays and flow cytometry. Western blot assay was performed for the expression determination of all proteins. The predicted interaction between miR-557 and circEIF6 or SLC7A11 was confirmed by dual-luciferase reporter assay. Xenograft tumor model was used for exploring the biological function of circEIF6 in vivo.

RESULTS

CircEIF6 abundance was aberrantly up-regulated in pancreatic tumor tissues and cell lines. Cell proliferation, migration and invasion were significantly restrained while cell apoptosis was induced with the silencing of circEIF6 in pancreatic cancer cells. CircEIF6 silencing also hampered the activation of phosphatidylinositol 3-kinase (PI3K)/AKT serine/threonine kinase (AKT) pathway. CircEIF6 bound to miR-557, and circEIF6 silencing elevated the expression of miR-557 in pancreatic cancer cells. MiR-557 knockdown partly overturned circEIF6 silencing-induced effects in pancreatic cancer cells. SLC7A11 was a target of miR-557, and miR-557 overexpression suppressed malignant potential of pancreatic cancer cells partly through reducing the expression of SLC7A11. CircEIF6 knockdown blocked xenograft tumor growth in vivo.

CONCLUSION

CircEIF6 aggravated pancreatic cancer development through promoting cell proliferation, migration and invasion and suppressing cell apoptosis through targeting miR-557/SLC7A11/PI3K/AKT signaling.

hsa_circ_0000520 influences herceptin resistance in gastric cancer cells through PI3K-Akt signaling pathway

Background

To investigate whether hsa_circ_0000520 affects Herceptin resistance in gastric cancer by regulating the PI3K‐AKT signaling.

Methods

The expression of hsa_circ_0000520 was detected by qRT‐PCR in gastric cancer tissues and cell lines. A Herceptin‐resistant gastric cancer cell was established. PcDNA and pcDNA‐hsa_circ_0000520 were transfected into NCI‐N87R cells and treated with Herceptin at a concentration of 10 μg/mL for 24 hours. MTT tested cell proliferation, and apoptosis was measured by flow cytometry. IGF‐1 treatment was used to activate PI3K‐Akt signaling. The expression levels of related proteins were detected.

Results

The expression of hsa_circ_0000520 was reduced in gastric cancer tissues and cell lines, and hsa_circ_0000520 in NCI‐N87R cells was significantly lower than that of NCI‐N87 cells. Compared with the CON group, the cell viability of the Herceptin group was significantly reduced, the apoptosis rate was significantly increased, the level of Bax protein was significantly increased, and the levels of Bcl‐2, p‐PI3K, and p‐Akt protein were significantly reduced. Compared with the Herceptin + pcDNA group, the cell viability of the Herceptin + hsa_circ_0000520 group was significantly reduced, the apoptosis rate was significantly increased, the level of Bax protein was significantly increased, and the levels of p‐PI3K and p‐Akt proteins were significantly reduced. After IGF‐1 treatment, the cell viability was significantly increased, the apoptosis rate was significantly reduced, the level of Bax protein was significantly reduced, and the level of Bcl‐2 protein was significantly increased.

Conclusion

Hsa_circ_0000520 overexpression may reverse the Herceptin resistance of gastric cancer cells by inhibiting the PI3K‐Akt signaling pathway.