Circular RNA circ-LDLRAD3 serves as an oncogene to promote non-small cell lung cancer progression by upregulating SLC1A5 through sponging miR-137

miR-137: a potential therapeutic target for lung cancer

Lung cancer is a prevalent malignancy and the leading cause of cancer-related deaths, posing a significant threat to human health. Despite advancements in treatment, the prognosis for lung cancer patients remains poor due to late diagnosis, cancer recurrence, and drug resistance. Epigenetic research, particularly in microRNAs, has introduced a new avenue for cancer prevention and treatment. MicroRNAs, including miR-137, play a vital role in tumor development by regulating various cellular processes. MiR-137 has garnered attention for its tumor-suppressive properties, with studies showing its potential in inhibiting cancer progression. In lung cancer, miR-137 is of particular interest, with numerous reports exploring its role and mechanisms. A comprehensive review is necessary to consolidate current evidence. This review highlights recent studies on miR-137 in lung cancer, covering cell proliferation, migration, apoptosis, drug resistance, and therapy, emphasizing its potential as a biomarker and therapeutic target for lung cancer treatment and prognosis.

Particulate matter facilitates amphiregulin-dependent lung cancer proliferation through glutamine metabolism

Although many cohort studies have reported that long-term exposure to particulate matter (PM) causes lung cancer, the molecular mechanisms underlying the PM-induced increases in lung cancer progression remain unclear. We applied the lung cancer cell line A549 (Parental; A549.Par) to PM for an extended period to establish a mimic PM-exposed lung cancer cell line, A549.PM. Our results indicate that A549.PM exhibits higher cell growth and proliferation abilities compared to A549.Par cells in vitro and in vivo. The RNA sequencing analysis found amphiregulin (AREG) plays a critical role in PM-induced cell proliferation. We observed that PM increases AREG-dependent lung cancer proliferation through glutamine metabolism. In addition, the EGFR/PI3K/AKT/mTOR signaling pathway is involved in PM-induced solute carrier family A1 member 5 (SLC1A5) expression and glutamine metabolism. Our findings offer important insights into how lung cancer proliferation develops upon exposure to PM.

Non-coding RNAs and exosomal non-coding RNAs in lung cancer: insights into their functions

Lung cancer is the second most common form of cancer worldwide Research points to the pivotal role of non-coding RNAs (ncRNAs) in controlling and managing the pathology by controlling essential pathways. ncRNAs have all been identified as being either up- or downregulated among individuals suffering from lung cancer thus hinting that they may play a role in either promoting or suppressing the spread of the disease. Several ncRNAs could be effective non-invasive biomarkers to diagnose or even serve as effective treatment options for those with lung cancer, and several molecules have emerged as potential targets of interest. Given that ncRNAs are contained in exosomes and are implicated in the development and progression of the malady. Herein, we have summarized the role of ncRNAs in lung cancer. Moreover, we highlight the role of exosomal ncRNAs in lung cancer.

Silencing circLDLRAD3 Inhibits Lung Cancer Progression by Regulating the miR-497-5p/PFKP Axis

PURPOSE

Lung cancer is one of the leading causes of death worldwide. Recent studies have shown that circular RNAs are dysregulated in a variety of cancers, but the mechanism in lung cancer is still indistinct. In our work, we explored the action mechanism of circLDLRAD3 in lung cancer.

METHODS

The abundance of circLDLRAD3, microRNA-497-5p (miR-497-5p) and platelet-type PFK (PFKP) was measured by real-time quantitative polymerase chain reaction (RT-qPCR) in lung cancer. Meanwhile, the level of PFKP was quantified by western blot. Cell counting kit-8 (CCK-8), 5-Ethynyl-2'-deoxyuridine (EdU) assay, transwell assay, wound healing assay, flow cytometry, western blot, immunohistochemical (IHC) assay and glycolysis metabolism analysis were performed for functional analyses. Furthermore, the interplay between miR-497-5p and circLDLRAD3 or FKPF was detected by the dual-luciferase reporter and RNA Immunoprecipitation (RIP) assays. Eventually, the in vivo experiments were applied to measure the role of circLDLRAD3.

RESULT

The levels of circLDLRAD3 and PFKP were increased. Silencing circLDLRAD3 inhibited cell viability, proliferation, migration, invasion and glycolysis metabolism and promoted cell apoptosis in lung cancer cells. In mechanism, circLDLRAD3 regulated PFKP level as a miR-497-5p sponge. MiR-497-5p suppressed the progression of lung cancer by inhibiting PFKP. In addition, circLDLRAD3 knockdown also inhibited tumor growth in vivo.

CONCLUSION

CircLDLRAD3 promoted the development of lung cancer through increasing PFKP expression by regulating miR-497-5p, which also provided a potential targeted therapy for lung cancer treatment.

Long non-coding RNAs in cancer: multifaceted roles and potential targets for immunotherapy

Cancer remains a major global health concern with high mortality rates mainly due to late diagnosis and poor prognosis. Long non-coding RNAs (lncRNAs) are emerging as key regulators of gene expression in human cancer, functioning through various mechanisms including as competing endogenous RNAs (ceRNAs) and indirectly regulating miRNA expression. LncRNAs have been found to have both oncogenic and tumor-suppressive roles in cancer, with the former promoting cancer cell proliferation, migration, invasion, and poor prognosis. Recent research has shown that lncRNAs are expressed in various immune cells and are involved in cancer cell immune escape and the modulation of the tumor microenvironment, thus highlighting their potential as targets for cancer immunotherapy. Targeting lncRNAs in cancer or immune cells could enhance the anti-tumor immune response and improve cancer immunotherapy outcomes. However, further research is required to fully understand the functional roles of lncRNAs in cancer and the immune system and their potential as targets for cancer immunotherapy. This review offers a comprehensive examination of the multifaceted roles of lncRNAs in human cancers, with a focus on their potential as targets for cancer immunotherapy. By exploring the intricate mechanisms underlying lncRNA-mediated regulation of cancer cell proliferation, invasion, and immune evasion, we provide insights into the diverse therapeutic applications of these molecules.

Screening microRNAs as potential prognostic biomarkers for lung adenocarcinoma

OBJECTIVE

To screen and identify microRNAs (miRNAs) associated with the prognosis of lung adenocarcinoma (LUAD) using clinical samples and construct a prediction model for the prognosis of LUAD.

METHODS

160 patient samples were used to screen and identify miRNAs associated with the prognosis of LUAD. Differentially expressed miRNAs were analyzed using gene chip technology. The selected miRNAs were validated using samples from the validation sample group. Cox proportional hazards regression was used to construct the model and Kaplan-Meier was used to plot survival curves. Model power was assessed by testing the prognosis of the constructed model using real-time polymerase chain reaction (RT-PCR) data.

RESULTS

The data showed that miR-1260b, miR-21-3p and miR-92a-3p were highly expressed in the early recurrence and metastasis group, while miR-2467-3p, miR-4659a-3p, miR-4514, miR-1471 and miR-3621 were lowly expressed. It was further confirmed that miR-21-3p was significantly highly expressed in the early recurrence and metastasis group (p = 0.02). Receiver operating characteristic (ROC) curve results showed cut-off point value of 0.0172, sensitivity of 88.2% and specificity of 100%. The predictive results of the constructed model were in good agreement with the actual prognosis of patients by using the validation sample test (Kappa = 0.426, p < 0.001), with a model sensitivity of 74.4%, a specificity of 68.3%, and an accuracy of 71.3%.

CONCLUSION

miRNAs associated with the prognosis of patients with stage I LUAD were screened and validated, and a risk model for predicting the prognosis of patients was constructed. This model has good consistency with the actual prognosis of patients.

CircPKM2 aggravates the progression of non-small cell lung cancer by regulating MTDH via miR-1298-5p

BACKGROUND

Non-small cell lung cancer (NSCLC) is the most common type of lung cancer with high morbidity and mortality. The role of dysregulated circular RNAs (circRNAs) in human diseases are receiving more and more attention. In this study, we focused on the role and mechanism of circPKM2 in the progression of NSCLC.

METHODS

The expression levels of circPKM2, microRNA-1298-5p (miR-1298-5p) and metadherin (MTDH) in NSCLC were measured by real-time quantitative PCR (qRT-PCR) or Western blot. Cell counting kit-8 (CCK-8), colony formation, 5-ethynyl-2'-deoxyuridine (EdU) staining, flow cytometry, transwell and tube formation assays were conducted to evaluate the effects of circPKM2 on malignant phenotypes of NSCLC. Western blot was used to measure related marker protein levels.

RESULTS

CircPKM2 and MTDH were highly expressed in NSCLC tissues and cells, while miR-1298-5p was downregulated. CircPKM2 knockdown effectively suppressed cell proliferation, migration, invasion and tube formation whereas induced apoptosis in vitro. CircPKM2 had a potential targeting site with miR-1298-5p and negatively regulated the expression of miR-1298-5p. MiR-1298-5p inhibitor reversed the effect of circPKM2 knockdown on the progression of NSCLC. CircPKM2 induced MTDH expression via sponging miR-1298-5p to promote the progression of NSCLC. MiR-1298-5p directly targeted MTDH, and the addition of MTDH partially attenuated the inhibition of miR-1298-5p on the progression of NSCLC. In addition, the downregulation of circPKM2 significantly slowed down the growth of xenograft tumors in vivo.

CONCLUSION

Our findings demonstrated that circPKM2 mediated NSCLC progression via regulating miR-1298-5p/MTDH axis, providing a novel therapeutic target for NSCLC.

Expression status of circ-SMARCA5, circ-NOL10, circ-LDLRAD3, and circ-RHOT1 in patients with colorectal cancer

Colorectal cancer (CRC) poses a significant burden on both the healthcare systems as well as individuals. The high mortality rate of CRC may be attributed to its metastatic potential, heterogeneity, and delayed diagnosis. CircRNAs are an essential class of regulatory RNAs that play significant roles in cancers. This study aimed to detect the expression status of circ-SMARCA5, circ-NOL10, circ-LDLRAD3, and circ-RHOT1 in patients with CRC. This study included 50 CRC patients, 30 individuals with colorectal diseases (non-cancer), and 20 healthy volunteers. By using real-time PCR, the relative expression of circ-SMARCA5, circ-NOL10, circ-LDLRAD3, and circ-RHOT1 was determined in the collected blood samples. In addition, ECLIA was used to quantify carcinoembryonic antigen (CEA) level. All circRNAs expression and CEA levels were significantly up-regulated in cancer patients (CRC, colon, rectum) as compared to healthy controls, except circ-SMARCA5. Moreover, there was a significant up-regulation of circRNAs in most non-cancer patients (UC, polyp, piles). Insignificant upregulation was observed in circRNAs and CEA when comparing cancer with non-cancer patients. No correlations were found between the studied parameters and most clinicopathological characteristics of cancer and non-cancer patients. Circ-SMARCA5, circ-NOL10, circ-LDLRAD3, and circ-RHOT1 were differentially expressed in patients with CRC as well as in non-cancer patients. Circ-SMARCA5 and circ-NOL10 may act as tumor suppressors, while circ-LDLRAD3 and circ-RHOT1 may be oncogenes. Circ-SMARCA5, circ-NOL10, circ-LDLRAD3, and circ-RHOT1 could be promising markers for the early detection of CRC.

Circ_0079530 stimulates THBS2 to promote the malignant progression of non-small cell lung cancer by sponging miR-584-5p

BACKGROUND

Circ_0079530 has been confirmed to be a novel potential oncogene in non-small cell lung cancer (NSCLC). This study aims to explore the role and mechanism of circ_0079530 in NSCLC progression.

METHODS

Levels of circ_0079530, microRNA (miR)-584-5p, thrombospondin-2 (THBS2), PCNA, Bax, E-cadherin, and ki67 were detected by quantitative real-time PCR (qRT-PCR), western blotting and immunohistochemistry. The proliferation of NSCLC cells was measured using cell counting kit 8 (CCK8) assay, colony formation assay, and EdU staining. Cell apoptosis and motility were respectively detected by flow cytometry and transwell assays. Interaction between miR-584-5p and circ_0079530 or THBS2 was predicted by bioinformatics analysis and confirmed via luciferase reporter assay and RNA immunoprecipitation (RIP) assay. A xenograft tumor model was used to analyze the role of circ_0079530 in tumor growth in vivo.

RESULTS

Circ_0079530 was highly expressed in NSCLC tissues and cell lines. Circ_0079530 overexpression facilitated proliferation, migration, and invasion whereas it restrained the apoptosis of NSCLC cells. Circ_0079530 silence showed the opposite effects on the above malignant biological behaviors. Mechanistic analysis showed that circ_0079530 functioned as a sponge of miR-584-5p to relieve the suppressive action of miR-584-5p on its target THBS2. Additionally, circ_0079530 knockdown impeded the growth of xenografts in vivo.

CONCLUSION

Circ_0079530 promoted NSCLC progression by regulating the miR-584-5p/THBS2 axis, providing a possible circRNA-targeted therapy for NSCLC.

The role of noncoding RNAs in metabolic reprogramming of cancer cells

Metabolic reprogramming is a well-known feature of cancer that allows malignant cells to alter metabolic reactions and nutrient uptake, thereby promoting tumor growth and spread. It has been discovered that noncoding RNAs (ncRNAs), including microRNA (miRNA), long noncoding RNA (lncRNA), and circular RNA (circRNA), have a role in a variety of biological functions, control physiologic and developmental processes, and even influence disease. They have been recognized in numerous cancer types as tumor suppressors and oncogenic agents. The role of ncRNAs in the metabolic reprogramming of cancer cells has recently been noticed. We examine this subject, with an emphasis on the metabolism of glucose, lipids, and amino acids, and highlight the therapeutic use of targeting ncRNAs in cancer treatment.

CircRNA OXCT1 promotes the malignant progression and glutamine metabolism of non-small cell lung cancer by absorbing miR-516b-5p and upregulating SLC1A5

Previous study has demonstrated the high expression of circular RNA 3-oxoacid CoA-transferase 1 (circ-OXCT1) in lung adenocarcinoma tumor tissues. However, the role and possible mechanism of circ-OXCT1 in non-small cell lung cancer (NSCLC) progression was unclear.Quantitative real-time PCR (qRT-PCR), western blotting and immunohistochemistry (IHC) staining assay were performed to detect the expression of circ-OXCT1, microRNA-516b-5p (miR-516b-5p), solute carrier family 1 member 5 (SLC1A5) and other indicated protein markers. Cell proliferation was measured by Cell counting kit 8 (CCK8), colony formation and 5-Ethynyl-2'-deoxyuridine (EdU) assays. Flow cytometry was employed to detect the rate of apoptotic cells. Cell migration and invasion were measured using transwell assay. The relative glutamine uptake and α-ketoglutarate (α-KG) production was determined using commercial kits. Interaction between miR-516b-5p and circ-OXCT1 or SLC1A5 was predicted by bioinformatics analysis and confirmed via luciferase reporter and RNA immunoprecipitation (RIP) assays. In vivo assay was implemented to demonstrate the effect of circ-OXCT1 in tumor growth.Circ-OXCT1 and SLC1A5 were upregulated and miR-516b-5p was downregulated in NSCLC tissues and cells. Functional experiments revealed that circ-OXCT1 silencing suppressed cell proliferation, migration and invasion, but promoted cell apoptosis in vitro. Circ-OXCT1 knockdown repressed tumor formation in vivo. Besides, miR-516b-5p was a target of circ-OXCT1, and miR-516b-5p inhibitor could relieve circ-OXCT1 absence-mediated effects in NSCLC cells. SLC1A5 was identified as a target of miR-516b-5p. Circ-OXCT1 promoted SLC1A5 expression by target binding with miR-516b-5p.Circ-OXCT1 facilitated NSCLC progression via miR-516b-5p-dependent regulation of SLC1A5, which provided a possible circRNA-targeted therapy for NSCLC.

Circ_0001821 Potentiates Cell Growth, Metastasis, and Stemness in Colorectal Cancer by Regulating miR-339-3p/CST1

Dysregulation of circRNAs is associated with human cancer progression, but its expression pattern and function in cancer are not fully understood. The aim of our study is to investigate the effects of circ_0001821 on colorectal cancer (CRC) proliferation, migration, invasion, and stemness. The expression level of circ_0001821 in CRC tissues and cells was detected by quantitative real-time PCR. The effects of circ_0001821 silencing on the proliferation, migration, invasion, and stemness of CRC cells were examined by cell counting kit-8, 5-Ethynyl-2'-deoxyuridine, transwell, sphere formation, and western blot assays. Bioinformatics and dual-luciferase reporter gene assay were used to verify the relationship between circ_0001821 and miR-339-3p, miR-339-3p and CST1 in CRC cells. Circ_0001821 was highly expressed in CRC tissues and cells. Circ_0001821 silencing inhibited the proliferation, migration, invasion, and stemness of CRC cells, and transfection of miR-339-3p inhibitor partly attenuated this effect. In addition, circ_0001821 can bind miR-339-3p to regulate CST1 expression. Circ_0001821 silencing also curbed tumor growth in vivo. Circ_0001821 promoted CRC cell proliferation, migration, invasion, and stemness by regulating the miR-339-3p/CST1 axis.

Exosomal circular RNA: a signature for lung cancer progression

Membrane vesicles having a diameter of 30-150 nm are known as exosomes. Several cancer types secrete exosomes, which may contain proteins, circular RNAs (circRNAs), microRNAs, or DNA. CircRNAs are endogenous RNAs that do not code for proteins and can create continuous and covalently closed loops. In cancer pathogenesis, especially metastasis, exosomal circRNAs (exo-circRNAs) have a crucial role mainly due to the frequently aberrant expression levels within tumors. However, neither the activities nor the regulatory mechanisms of exo-circRNAs in advancing lung cancer (LC) are obvious. A better understanding of the regulation and network connections of exo-circRNAs will lead to better treatment for LCs. The main objective of the current review is to highlight the functions and mechanisms of exo-circRNAs in LC and assess the relationships between exo-circRNA dysregulation and LC progression. In addition, underline the possible therapeutic targets based on exo-circRNA modulating.

Epigenetic Regulation in Chromium-, Nickel- and Cadmium-Induced Carcinogenesis

Environmental and occupational exposure to heavy metals, such as hexavalent chromium, nickel, and cadmium, are major health concerns worldwide. Some heavy metals are well-documented human carcinogens. Multiple mechanisms, including DNA damage, dysregulated gene expression, and aberrant cancer-related signaling, have been shown to contribute to metal-induced carcinogenesis. However, the molecular mechanisms accounting for heavy metal-induced carcinogenesis and angiogenesis are still not fully understood. In recent years, an increasing number of studies have indicated that in addition to genotoxicity and genetic mutations, epigenetic mechanisms play critical roles in metal-induced cancers. Epigenetics refers to the reversible modification of genomes without changing DNA sequences; epigenetic modifications generally involve DNA methylation, histone modification, chromatin remodeling, and non-coding RNAs. Epigenetic regulation is essential for maintaining normal gene expression patterns; the disruption of epigenetic modifications may lead to altered cellular function and even malignant transformation. Therefore, aberrant epigenetic modifications are widely involved in metal-induced cancer formation, development, and angiogenesis. Notably, the role of epigenetic mechanisms in heavy metal-induced carcinogenesis and angiogenesis remains largely unknown, and further studies are urgently required. In this review, we highlight the current advances in understanding the roles of epigenetic mechanisms in heavy metal-induced carcinogenesis, cancer progression, and angiogenesis.

Six MicroRNA Prognostic Models for Overall Survival of Lung Adenocarcinoma

Objective

The purpose of this study is to screen for microRNAs (miRNAs) associated with the prognosis of lung adenocarcinoma (LUAD) and to explore its prognosis and effects on the tumor microenvironment in patients with LUAD.

Methods

Gene expression data, miRNA expression data, and clinical data for two different databases, TCGA-LUAD and CPTAC-3 LUAD, were downloaded from the GDC database. The miRNA prognosis of LUAD was filtered by the Cox proportional hazard model and the Least Absolute Shrinkage and Selection Operator (LASSO) regression model. The performance of the model was validated by time-dependent receiver operating characteristics (ROC) curves. Possible biological processes associated with the miRNAs target gene were analyzed through Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG). Finally, the prognostic model was scored by risk, divided into high- and low-risk groups by median, and the differences in the immersion level of 21 immune cells in the high- and low-risk groups were assessed. To gain a deeper understanding of the underlying mechanism behind the model, the two most important miRNAs in the model, miR-195-3p and miR-5571-5p, were selected for HPA database validation and ceRNA network construction.

Results

Of the 209 variance expressions identified in the screening analysis, 145 were upregulated and 64 were downregulated by miRNAs. The prognostic models of six miRNA genes were obtained: miR-195-3p, miR-5571-5p, miR-584-3p, miR-494-3p, miR-4664-3p, and miR-1293. These six genes were significantly associated with survival rates in LUAD patients. In particular, miR-1293, miR-195-3p, and miR-5571-5p are highly correlated with OS. The higher expression of miR-195-3p and miR-5571-5p, the better survival of LUAD OS is, and these two miRNA expressions contribute the most to the model. Finally, after sorting the risk scores calculated from low to high using the prognostic model, the patients with higher scores had shorter survival time and higher frequency of death, and there were significant differences in the immersion levels of 21 immune cells in the high- and low-risk groups. ceRNA network analysis found that TM9SF3 was regulated by miR-195-3p and was highly expressed in the tissues of LUAD patients, and the prognosis of the patients was poor.

Conclusions

miR-195-3p, miR-5571-5p, miR-584-3p, miR-494-3p, miR-4664-3p, and miR-1293 may be used as new biomarkers for prognosis prediction of LUAD. Our results also identified a lncRNA MEG3/miR-195-3p/RAB1A/TM9SF3 regulatory axis, which may also play an important role in the progression of LUAD. Further study needs to be conducted to verify this result.

Long Noncoding RNAs and Circular RNAs in the Metabolic Reprogramming of Lung Cancer: Functions, Mechanisms, and Clinical Potential

As key regulators of gene function, long noncoding RNAs (lncRNAs) and circular RNAs (circRNAs) are generally accepted to be involved in lung cancer pathogenesis and progression. Recent research has clarified the phenomenon of metabolic reprogramming in lung cancer because of its significant role in tumor proliferation, migration, invasion, metastasis, and other malignant biological behaviors. Emerging evidence has also shown a relationship between the aberrant expression of lncRNAs and circRNAs and metabolic reprogramming in lung cancer tumorigenesis. This review provides insight regarding the roles of different lncRNAs and circRNAs in lung cancer metabolic reprogramming, by how they target transporter proteins and key enzymes in glucose, lipid, and glutamine metabolic signaling pathways. The clinical potential of lncRNAs and circRNAs as early diagnostic biomarkers and components of therapeutic strategies in lung cancer is further discussed, including current challenges in their utilization from the bench to the bedside and how to adopt a proper delivery system for their therapeutic use.

Non-coding RNAs in ferroptotic cancer cell death pathway: meet the new masters

Despite the recent advances in cancer therapy, cancer chemoresistance looms large along with radioresistance, a major challenge in dire need of thorough and minute investigation. Not long ago, cancer cells were reported to have proven refractory to the ferroptotic cell death, a newly discovered form of regulated cell death (RCD), conspicuous enough to draw attention from scholars in terms of targeting ferroptosis as a prospective therapeutic strategy. However, our knowledge concerning the underlying molecular mechanisms through which cancer cells gain immunity against ferroptosis is still in its infancy. Of late, the implication of non-coding RNAs (ncRNAs), including circular RNAs (circRNAs), microRNAs (miRNAs), and long non-coding RNAs (lncRNAs) in ferroptosis has been disclosed. Nevertheless, precisely explaining the molecular mechanisms behind the contribution of ncRNAs to cancer radio/chemotherapy resistance remains a challenge, requiring further clarification. In this review, we have presented the latest available information on the ways and means of regulating ferroptosis by ncRNAs. Moreover, we have provided important insights about targeting ncRNAs implicated in ferroptosis with the hope of opening up new horizons for overcoming cancer treatment modalities. Though a long path awaits until we make this ambitious dream come true, recent progress in gene therapy, including gene-editing technology will aid us to be optimistic that ncRNAs-based ferroptosis targeting would soon be on stream as a novel therapeutic strategy for treating cancer.

Circ_0062558 promotes growth, migration, and glutamine metabolism in triple-negative breast cancer by targeting the miR-876-3p/SLC1A5 axis

BACKGROUND

Circular RNAs (circRNAs) have been reported to function as vital regulators in cancers, including triple-negative breast cancer (TNBC). This study aimed to explore the role of circ_0062558 in TNBC.

METHODS

The real-time quantitative polymerase chain reaction (RT-qPCR) was conducted to quantify the expressions of circ_0062558, microRNA-876-3p (miR-876-3p), and solute carrier family 1 (neutral amino acid transporter), member 5 (SLC1A5) in TNBC tissues and cells. 3-(4, 5-Dimethylthiazol-2-yl)-2, 5-diphenyl-2H-tetrazol-3-ium bromide (MTT), thymidine analog 5-ethynyl-2'-deoxyuridine (EdU), flow cytometry, wound healing, and Transwell assays were employed for cell phenotype analyses. Protein expression was tested by western blot analysis. Dual-luciferase reporter was used to confirm the association among circ_0062558, miR-876-3p, and SLC1A5 in TNBC. Xenograft experiments were performed to elucidate the function of circ_0062558 in vivo.

RESULTS

TNBC tissues and cells showed the higher level of circ_0062558 when compared with control samples. Downregulation of circ_0062558 inhibited proliferation, migration, invasion, and glutamine metabolism, while enhanced apoptosis of TNBC cells, and silencing of circ_0062558 also inhibited the growth of tumor in vivo. MiR-876-3p was confirmed as a target of circ_0062558, and circ_0062558 knockdown repressed TNBC cell malignant behaviors by increasing miR-876-3p. Furthermore, miR-876-3p inhibited malignant behaviors of TNBC cells by down-regulating SLC1A5, a newly identified target of miR-876-3p.

CONCLUSION

Circ_0062558 promoted TNBC progression by enhancing proliferation, survival, migration, invasion, and glutamine metabolism via miR-876-3p/SLC1A5 axis, which was helpful for understanding the carcinogenic roles of circ_0062558.

Therapeutic Potential of Glutamine Pathway in Lung Cancer

Cancer cells tend to obtain the substances needed for their development depending on altering metabolic characteristics. Among the reorganized metabolic pathways, Glutamine pathway, reprogrammed to be involved in the physiological process including energy supply, biosynthesis and redox homeostasis, occupies an irreplaceable role in tumor cells and has become a hot topic in recent years. Lung cancer currently maintains a high morbidity and mortality rate among all types of tumors and has been a health challenge that researchers have longed to overcome. Therefore, this study aimed to clarify the essential role of glutamine pathway played in the metabolism of lung cancer and its potential therapeutic value in the interventions of lung cancer.

Knockdown of circ-RAD23B inhibits non-small cell lung cancer progression via the miR-142-3p/MAP4K3 axis

Background

The development of non‐small cell lung cancer (NSCLC) is associated with the deregulation of circRNAs. The objective of this study was to investigate the effects of circ‐RAD23B in NSCLC.

Methods

Circ‐RAD23B expression, miR‐142‐3p and MAP4K3 was detected by qPCR. Cell proliferation was investigated by CCK‐8 assay and colony formation assay. Cell migration and invasion were assessed by transwell assay. Angiogenesis ability was assessed by tube formation assay. Cell cycle distribution and cell apoptosis were monitored by flow cytometry. The predicted binding relationship between miR‐142‐3p and circ‐RAD23B or MAP4K3 was verified by dual‐luciferase reporter assay. The protein level of MAP4K3 was detected by western blot. Animal models were established to determine the role of circ‐RAD23B in vivo.

Results

Circ‐RAD23B was shown to be upregulated in NSCLC tissues and cells. Knockdown of circ‐RAD23B inhibited proliferation, migration, invasion, angiogenesis and promoted cell cycle arrest and apoptosis in NSCLC cells, and circ‐RAD23B knockdown also impeded tumor growth in vivo. Circ‐RAD23B acted as miR‐142‐3p sponge to inhibit miR‐142‐3p expression and thus enrich the expression of MAP4K3, a target of miR‐142‐3p. Rescue experiments presented that miR‐142‐3p inhibition reversed the effects of circ‐RAD23B knockdown, and MAP4K3 overexpression abolished the effects of miR‐142‐3p restoration. In addition, we found that circ‐RAD23B knockdown led to decreased phosphorylation expression of ERK1/2, JNK and p38, three key groups of the MAPK signaling pathway.

Conclusions

Circ‐RAD23B knockdown inhibited NSCLC development by regulating the miR‐142‐3p/MAP4K3 axis, which might be associated with the inactivation of the MAPK signaling pathway.

Circular RNA CCDC66 Improves Murine Double Minute 4 (MDM4) Expression through Targeting miR-370 in Colorectal Cancer

Introduction

Colorectal cancer (CRC), a common digestive tract tumor that contains colon and rectal cancer, is one of the three most common cancers globally. circRNAs are involved in the occurrence and development of CRC, but the mechanism of how they participate in this process remains unclear.

Methods

We adopted PCR for expression measure, CCK-8 for cell proliferation detection, Transwell for cell migration and invasion detection, and dual-luciferase reporter assays to detect the potential downstream targets of CCDC66 in CRC.

Results

This study showed that circRNA CCDC66 was overexpressed in CRC tissues, and after knockdown, it inhibited the proliferation, migration, and invasion of CRC cells (RKO and HCT-116) in vitro. In addition, the dual-luciferase reporter assay showed that there was a binding site between circCCDC66 and miR-370, as well as between miR-370 and murine double minute 4 (MDM4). That is, circCCDC66 upregulated the expression of MDM4 through competitively binding to miR-370. The expression of circCCDC66 in CRC tissues was positively correlated with MDM4 and negatively correlated with miR-370.

Conclusion

In summary, our results indicate that circCCDC66 is a key upregulation of CRC. circCCDC66 upregulates MDM4 through competitive binding to miR-370, thereby enhancing the metastatic ability of CRC cells and promoting the development of CRC.

circRNA LDLRAD3 Enhances the Malignant Behaviors of NSCLC Cells via the miR-20a-5p-SLC7A5 Axis Activating the mTORC1 Signaling Pathway

Circular RNA LDLRAD3 behaved as an oncogene in several malignancies, but its effects in NSCLC and the involvement of downstream molecules and activation of signaling pathways had not been fully reported. We planned to explore how LDLRAD3 facilitated the malignancy of NSCLC. QRT-PCR was performed to evaluate the expression levels of LDLRAD3, miR-20a-5p, and SLC7A5 in NSCLC tissues and cells. si-LDLRAD3 was transfected to A549 and H1299 cells to knock down intrinsic LDLRAD3 to determine its oncogenic roles. CCK-8 assay and transwell assay were executed to assess cell proliferative, migrative, and invasive abilities. Dual-luciferase reporter (DLR) assay was manipulated to verify the ENCORI-predicted relationships between LDLRAD3 and miR-20a-5p and between miR-20a-5p and SLC7A5. Western blot, immunofluorescent assay, and immunohistochemistry were applied to explore the expression levels of SLC7A5, and the levels of mTORC1 pathway-related proteins were evaluated using western blot. Rescue experiments were conducted by transfecting si-LDLRAD3, miR-20a-5p inhibitor, and si-SLC7A5 to explore the influence of the LDLRAD3-miR-20a-5p-SLC7A5 axis on the malignant behaviors of NSCLC cells. The expression levels of LDLRAD3 and SLC7A5 were boosted, whereas miR-20a-5p was impeded in NSCLC tissues and cell lines. Knockdown of LDLRAD3 weakened the proliferation, migration, and invasion of A549 and H1299 cells. LDLRAD3 was verified to sponge miR-20a-5p and miR-20a-5p targeted SLC7A5. LDLRAD3 activated the mTORC1 singling pathway via the miR-20a-5p-SLC7A5 axis to strengthen the malignant properties of A549 and H1299 cells. We concluded that LDLRAD3 exerted oncogenic effects via the miR-20a-5p-SLC7A5 axis to activate the mTORC1 signaling pathway in NSCLC. Our findings enlightened that LDLRAD3 could become a potential therapeutic target in the treatment and management of NSCLC.

Circ_0000463 contributes to the progression and glutamine metabolism of non-small-cell lung cancer by targeting miR-924/SLC1A5 signaling

Background

Circular RNAs (circRNAs) have shown pivotal regulatory roles in the pathology of non‐small cell lung cancer (NSCLC). However, the role of circ_0000463 in NSCLC progression and its associated molecular mechanism remain to be illustrated.

Methods

Cell proliferation ability was analyzed by colony formation assay and 5‐ethynyl‐2’‐deoxyuridine (EdU) assay. Cell migration and invasion abilities were assessed by scratch test and transwell invasion assay. Flow cytometry was employed to analyze cell apoptotic rate. The interaction between microRNA‐924 (miR‐924) and circ_0000463 or solute carrier family 1 member 5 (SLC1A5) was confirmed by dual‐luciferase reporter assay and RNA immunoprecipitation (RIP) assay. The uptake of glutamine and the production of glutamate and α‐ketoglutarate were analyzed using their corresponding kits. Xenograft model in vivo was established to analyze the role of circ_0000463 in tumor growth.

Results

Circ_0000463 expression was elevated in NSCLC tissues and cell lines. Circ_0000463 knockdown suppressed the proliferation, migration, and invasion and promoted the apoptosis of NSCLC cells. Circ_0000463 acted as a molecular sponge for miR‐924, and circ_0000463 interference‐mediated anti‐tumor effects were largely reversed by the silence of miR‐924 in NSCLC cells. miR‐924 interacted with the 3’ untranslated region (3’UTR) of SLC1A5, and SLC1A5 overexpression largely overturned miR‐924 overexpression‐mediated anti‐tumor effects in NSCLC cells. Moreover, circ_0000463 absence suppressed the glutamine metabolism of NSCLC cells by targeting miR‐924/SLC1A5 axis. Circ_0000463 knockdown suppressed xenograft tumor growth in vivo.

Conclusion

Circ_0000463 absence suppressed the malignant behaviors and glutamine metabolism of NSCLC cells through mediating miR‐924/SLC1A5 axis.

Identification of ubiquitinated substrate proteins and their gene expression patterns in lung adenocarcinoma

Background

Lung cancer is a malignant disease with the highest cancer-related mortality rate. In lung adenocarcinoma (LUAD), protein ubiquitination can regulate multiple biological processes. A LUAD ubiquitylome analysis has not yet been reported.

Methods

We used for the first time ion mobility into liquid chromatography-mass spectrometry to perform accurate and reliable ubiquitylome and proteomic analysis of clinical LUAD and normal tissues and combined it with transcriptome data obtained from public databases. Ubiquitinated protein substrates and their gene expression pattern landscapes in LUAD were identified using bioinformatics methods.

Results

Our data revealed a ubiquitination landscape in LUAD and identified characteristic protein ubiquitination motifs. We found that the ubiquitinated peptide motifs in LUAD were completely different from those of previously published lung squamous cell carcinoma (LUSC). Moreover, we identified two gene expression patterns of ubiquitinated proteins and revealed that survival differences between these patterns may be correlated with the tumor immune infiltrating microenvironment. Finally, we constructed a prognostic predictive model to quantify the relationship between expression patterns and survival. We found a relationship between the patient-applied model score and multiple drug sensitivity. Therefore, our model can serve as a guide for LUAD clinical treatment.

Conclusions

Our work addresses the lack of ubiquitylome studies in LUAD and provides new perspectives for subsequent research and clinical treatment.

Circular RNAs in Lung Cancer: Recent Advances and Future Perspectives

Globally, lung cancer is the most commonly diagnosed cancer and carries with it the greatest mortality rate, with 5-year survival rates varying from 4–17% depending on stage and geographical differences. For decades, researchers have studied disease mechanisms, occurrence rates and disease development, however, the mechanisms underlying disease progression are not yet fully elucidated, thus an increased understanding of disease pathogenesis is key to developing new strategies towards specific disease diagnoses and targeted treatments. Circular RNAs (circRNAs) are a class of non-coding RNA widely expressed in eukaryotic cells, and participate in various biological processes implicated in human disease. Recent studies have indicated that circRNAs both positively and negatively regulate lung cancer cell proliferation, migration, invasion and apoptosis. Additionally, circRNAs could be promising biomarkers and targets for lung cancer therapies. This review systematically highlights recent advances in circRNA regulatory roles in lung cancer, and sheds light on their use as potential biomarkers and treatment targets for this disease.

Circ_0006988 promotes the proliferation, metastasis and angiogenesis of non-small cell lung cancer cells by modulating miR-491-5p/MAP3K3 axis

Circular RNAs (circRNAs) are related to the progression of non-small cell lung cancer (NSCLC). However, the roles and mechanism of circ_0006988 are largely unknown. The levels of circ_0006988, Low-Density Lipoprotein Receptor Class A Domain Containing 3 (LDLRAD3), microRNA-491-5p (miR-491-5p), Mitogen-Activated Protein Kinase Kinase Kinase 3 (MAP3K3) were measured using quantitative real-time polymerase-chain reaction (qRT-PCR) and western blot assay. The characteristic of circ_0006988 was analyzed by RNase R assay and Actinomycin D assay. Functional analyses were processed by Cell Counting Kit-8 (CCK-8) assay, 5-ethynyl-2'-deoxyuridine (EdU) assay, colony formation assay, flow cytometry analysis, transwell assay, wound-healing assay and tube formation assay. The interactions between circ_0006988 and miR-491-5p as well as miR-491-5p and MAP3K3 were analyzed by dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assay. Murine xenograft model assay was processed to verify the function of circ_0006988 in vivo. Immunohistochemistry (IHC) assay was conducted to examine the level of Ki67. Circ_0006988 abundance was increased in NSCLC tissues and cells. Circ_0006988 silencing restrained NSCLC cell proliferation, migration, invasion and angiogenesis, and induced apoptosis. Circ_0006988 sponged miR-491-5p, which directly targeted MAP3K3. MiR-491-5p overexpression repressed NSCLC cell malignant behaviors. MiR-491-5p downregulation or MAP3K3 overexpression reversed the effect of circ_0006988 silencing on NSCLC cell progression. In addition, circ_0006988 knockdown reduced xenograft tumor growth. ssCirc_0006988 contributed to the development of NSCLC by miR-491-5p/MAP3K3 axis.

Circular RNA circPVT1 Contributes to Doxorubicin (DXR) Resistance of Osteosarcoma Cells by Regulating TRIAP1 via miR-137

Background

Chemoresistance is a major obstacle to the treatment of osteosarcoma patients. Circular RNA (circRNA) circPVT1 has been reported to be related to the doxorubicin (DXR) resistance in osteosarcoma. This study is designed to explore the role and mechanism of circPVT1 in the DXR resistance of osteosarcoma.

Methods

circPVT1, microRNA-137 (miR-137), and TP53-regulated inhibitor of apoptosis 1 (TRIAP1) levels were detected by real-time quantitative polymerase chain reaction (RT-qPCR). The protein levels of ATP-binding cassette, subfamily C, member 1 (ABCC1), multidrug resistance-associated protein 1 (MRP-1), cleaved- (c-) caspase-3, B-cell lymphoma-2 (Bcl-2), and TRIAP1 were examined by a western blot assay. Cell viability, proliferation, and apoptosis were detected by cell counting kit-8 (CCK-8), colony formation, and flow cytometry assays, severally. The binding relationship between miR-137 and circPVT1 or TRIAP1 was predicted by starbase 3.0 and then verified by dual-luciferase reporter and RNA Immunoprecipitation (RIP) assays. The biological role of circPVT1 in osteosarcoma tumor growth and drug resistance was examined by the xenograft tumor model in vivo. Results. circPVT1 and TRIAP1 were highly expressed, and miR-137 was decreased in DXR-resistant osteosarcoma tissues and cells. Moreover, circPVT1 knockdown could boost DXR sensitivity by inhibiting DXR-caused proliferation and DXR-induced apoptosis in DXR-resistant osteosarcoma cells in vitro. The mechanical analysis discovered that circPVT1 acted as a sponge of miR-137 to regulate TRIAP1 expression. circPVT1 silencing increased the drug sensitivity of osteosarcoma in vivo. Conclusion. circPVT1 boosted DXR resistance of osteosarcoma cells partly by regulating the miR-137/TRIAP1 axis, hinting a promising therapeutic target for the osteosarcoma treatment.

Non-coding RNA in cancer

Majority of the human genome is transcribed to RNAs that do not encode proteins. These non-coding RNAs (ncRNAs) play crucial roles in regulating the initiation and progression of various cancers. Given the importance of the ncRNAs, the roles of ncRNAs in cancers have been reviewed elsewhere. Thus, in this review, we mainly focus on the recent studies of the function, regulatory mechanism and therapeutic potential of the ncRNAs including microRNA (miRNA), long ncRNA (lncRNA), circular RNA (circRNA) and PIWI interacting RNA (piRNA), in different type of cancers.

Circ-AASDH functions as the progression of early stage lung adenocarcinoma by targeting miR-140-3p to activate E2F7 expression

Background

Lung adenocarcinoma (LUAD), which is the most common subtype of non-small cell lung cancer, is a leading course of cancer-related mortality worldwide. Recently, circular RNA (CircRNAs) has become a hot spot in cancer research because of its important role in tumorigenesis and development and its superior stability. This study aims to clarify the role of circ-AASDH in LUAD and explore its competitive endogenous RNA mechanism.

Methods

The circ-AASDH, miR-140-3p and E2F transcription factor 7 (E2F7) mRNA expression levels were detected via qRT-PCR. CCK-8 and colony formation assay were used to evaluate the ability of cell proliferation. Transwell assay and wound healing assay were performed to measure the invasion and migration ability. Flow cytometry was used to detect the apoptosis of cells. Moreover, Sanger sequencing, RNaseR treatment and divergent primers were used to verify the circular structure. Luciferase reporter and RNA pull-down experiment were performed to characterize the ceRNA mechanism of circ-AASDH. The xenograft model of mice was established to investigate the tumorigenicity of circ-AASDH to LUAD in vivo.

Results

By screening for differentially expressed circRNAs, we found that circ-AASDH was highly expressed in LUAD tissues and cells and correlated with tumor size, clinical stage and poor prognosis. Transfection of si-circ-AASDH can inhibit the proliferation and migration of LUAD cells and promote apoptosis in vitro. In mechanism, circ-AASDH could be used as a sponge of miR-140-3p to weaken its inhibition on the expression of E2F7. Additionally, the overexpression of circ-AASDH could deduce the suppression of miR-140-3p on the malignant progression of LUAD cells. Besides, silencing of circ-AASDH inhibited cell proliferation and migration by regulating the expression of E2F7. Furthermore, overexpression of circ-AASDH can promote the growth of LUAD in vivo.

Conclusions

Circ-AASDH/miR-140-3p/E2F7 regulating axis promoted the progression in LUAD. Our results provided ideas for understanding the biological mechanism of circ-AASDH and clarify potential therapeutic targets in LUAD.