Circular RNA 103862 Promotes Proliferation and Invasion of Laryngeal Squamous Cell Carcinoma Cells Through the miR-493-5p/GOLM1 Axis

Roles and mechanisms of circular RNA in respiratory system cancers

Circular RNAs (circRNAs) constitute a class of endogenous non-coding RNAs (ncRNAs) that lack a 5'-ended cap and 3'-ended poly (A) tail and form a closed ring structure with covalent bonds. Due to its special structure, circRNA is resistant to Exonuclease R (RNaseR), making its distribution in the cytoplasm quite rich. Advanced high-throughput sequencing and bioinformatics methods have revealed that circRNA is highly conserved, stable, and disease- and tissue-specific. Furthermore, increasing research has confirmed that circRNA, as a driver or suppressor, regulates cancer onset and progression by modulating a series of pathophysiological mechanisms. As a result, circRNA has emerged as a clinical biomarker and therapeutic intervention target. This article reviews the biological functions and regulatory mechanisms of circRNA in the context of respiratory cancer onset and progression.

Exploring the evolving roles and clinical significance of circRNAs in head and neck squamous cell carcinoma

Head and neck squamous cell carcinoma (HNSCC) represents the predominant malignancies in the head and neck region, and has limited therapeutic alternatives. Circular RNAs (circRNAs), a substantial category of non-coding RNA molecules, exert influential roles in human disease development and progression, employing various mechanisms such as microRNA sponging, interaction with RNA-binding proteins, and translational capabilities. Accumulating evidence highlights the differential expression of numerous circRNAs in HNSCC, and numerous dysregulated circRNAs underscore their crucial involvement in malignant advancement and resistance to treatment. This review aims to comprehensively outline the characteristics, biogenesis, and mechanisms of circRNAs, elucidating their functional significance in HNSCC. In addition, we delve into the clinical implications of circRNAs, considering their potential as biomarkers or targets for diagnosis, prognosis, and therapeutic applications in HNSCC. The discussion extends to exploring future challenges in the clinical translation of circRNAs, emphasizing the need for further research.

High hsa_circ_0081621 expression indicates a poor prognosis of laryngeal squamous cell carcinoma: A bioinformatics analysis and retrospective clinical study

Laryngeal squamous cell carcinoma (LSCC) is the second most common malignant tumour of the head and neck with a low 5-year survival rate. There is need to identify novel biomarkers for diagnosis and treatment of LSCC. The present study identified differentially expressed circular RNAs (circRNAs/circs) in LSCC and larynx adjacent non-carcinoma epithelial specimens by analysing the circRNA microarray dataset GSE117001. hsa_circ_0081621 had highest expression among three circRNAs (hsa_circ_0015211, hsa_circ_0023326 and hsa_circ_0081621) in LSCC specimens by reverse transcription-quantitative PCR. The expression levels of hsa_circ_0081621 in 67 LSCC specimens were detected by fluorescence in situ hybridization (FISH). Expression levels of hsa_circ_0081621 were analysed in relation to clinicopathological parameters and prognosis of patients with LSCC. According to FISH results, 59.7% of LSCC specimens exhibited high hsa_circ_0081621 expression. In LSCC specimens, hsa_circ_0081621 high expression was associated with lymph node metastasis and high clinical stage. High expression levels of hsa_circ_0081621 were associated with a poor 5-year overall survival rate in patients with LSCC. In addition, high hsa_circ_0081621 expression was an independent prognostic factor for patients with LSCC. hsa_circ_0081621 may participate in malignant progression of LSCC, and its high expression could be used for prognostic assessment of patients with LSCC.

CircSERPINA3 promoted cell proliferation, migration, and invasion of laryngeal squamous cell carcinoma by targeting miR-885-5p

CircSERPINA3 has been shown to be upregulated in laryngeal squamous cell carcinoma (LSCC); however, whether it regulates the development of LSCC and the specific molecular mechanism remains unclear, which is to be explored in this study. Expressions of circSERPINA3, miR-885-5p, and Malic enzyme 1 (ME1) in LSCC tissues or cell lines were determined by quantitative reverse transcription polymerase chain reaction (qRT-PCR). The regulation of circSERPINA3 on the biological behavior of LSCC cells was confirmed by loss and gain experiments (cell counting kit-8, transwell, and colony formation assay). The correlation between circSERPINA3/ME1 and miR-885-5p was predicted and confirmed by bioinformatics analysis, dual-luciferase reporter assay, and qRT-PCR. The effect of circSERPINA3/miR-885-5p axis on the biological behavior of LSCC cells and expressions of epithelial-mesenchymal transition-related proteins was confirmed by rescue experiments. CircSERPINA3 and ME1 was upregulated in LSCC tissues, whereas miR-885-5p was downregulated. MiR-885-5p was the target gene of circSERPINA3, whereas ME1 was the target gene of miR-885-5p. Silent circSERPINA3 suppressed viability, invasion, migration, colony formation, and expression of ME1, claudin-4, snail, and vimentin but elevated expression of miR-885-5p and E-cadherin, whereas overexpressed circSERPINA3 was the opposite. However, miR-885-5p inhibitor or mimic reversed the effects of silent circSERPINA3 or overexpressed circSERPINA3. Collectively, circSERPINA3 promotes proliferation, migration, and invasion of LSCC cells by targeting miR-885-5p.

Emerging roles of PIWI-interacting RNAs (piRNAs) and PIWI proteins in head and neck cancer and their potential clinical implications

Head and neck squamous cell carcinoma (HNSCC) are among the well-known neoplasms originating in the oral cavity, pharynx, and larynx. Despite advancements in chemotherapy, radiotherapy, and surgery, the survival rates of the patients are low, which has posed a major therapeutic challenge. A growing number of non-coding RNAs (ncRNAs), for instance, microRNAs, have been identified whose abnormal expression patterns have been implicated in HNSCC. However, more recently, several seminal research has shown that piwi-interacting RNAs (piRNAs), a promising and young class of small ncRNA, are linked to the emergence and progression of cancer. They can regulate transposable elements (TE) and gene expression through multiple mechanisms, making them potentially more powerful regulators than miRNAs. Hence, they can be more promising ncRNAs candidates for cancer therapeutic intervention. Here, we surveyed the roles and clinical implications of piRNAs and their PIWI proteins partners in tumorigenesis and associated molecular processes of cancer, with a particular focus on HNSCC, to offer a new avenue for diagnosis, prognosis, and therapeutic interventions for the malignancy, improving patient's outcomes.

Diagnostic and prognostic value of circRNAs expression in head and neck squamous cell carcinoma: A meta-analysis

Background

Circular RNAs (circRNAs) have been found to have potential biological applications against tumors in humans. This study aimed to evaluate the diagnostic, prognostic, and clinicopathological value of circRNAs in head and neck squamous cell carcinoma (HNSCC).

Methods

The PubMed, Web of Science, EMBASE, and the Cochrane Library were comprehensively searched for the relevant studies before October 20, 2021. Statistical analysis was performed based on STATA 15.0, Meta‐DiSc 1.4, and RevMan 5.3 software.

Results

A total of 55 reports regarding 56 kinds of circRNA were studied in this meta‐analysis, including 23, 38, and 26 articles on diagnosis, prognosis, and clinicopathological features, respectively. The pooled sensitivity, specificity, and area under the curve (AUC) of the summary receiver‐operating characteristic curve (SROC) were 0.78, 0.84, and 0.87, respectively. Besides, the upregulation of oncogenic circRNAs was significantly associated with poorer overall survival (OS) (HR=2.25, p < 0.05) and disease‐free interval (DFS) (HR=1.92, p < 0.05). In contrast, the elevated expression of tumor suppressor circRNAs was associated with a favorable prognosis (HR=0.50, p < 0.05). In addition, the high expression of oncogenic circRNAs was associated with the tumor size (OR=3.59, p < 0.05), degree of differentiation (OR=1.89, p < 0.05), TNM stage (OR=2.35, p < 0.05), lymph node metastasis (OR=1.85, p < 0.05), and distant metastasis (OR=3.42, p < 0.05). Moreover, the expression of tumor suppressor circRNAs was associated with improved clinicopathological features (lymph node metastasis: OR=0.25, p < 0.05).

Conclusions

CircRNAs could serve as potential predictive indicators and be useful for the diagnosis, prognosis, and identification of clinicopathological features in HNSCC.

Hsa_circ_0042823 accelerates cancer progression via miR-877-5p/FOXM1 axis in laryngeal squamous cell carcinoma

BACKGROUND

Laryngeal squamous cell carcinoma (LSCC) is a common malignant tumour of the head and neck. Our previous study reveals that the circular RNA (circRNA) hsa_circ_0042823 is abnormally expressed in LSCC, suggesting that hsa_circ_0042823 is closely associated with LSCC. Here, we attempted to explore the molecular mechanism of hsa_circ_0042823 in LSCC.

METHODS

Quantitative real-time PCR and western blot were performed to assess the expression of gene and protein in human laryngeal carcinoma cells, TU212 and TU686. MTT and transwell assays were performed to examine cell proliferation, migration and invasion. The relationship among hsa_circ_0042823, miR-877-5p and forkhead box M1 (FOXM1) was verified by luciferase reporter assay. Finally, we constructed a subcutaneous tumour mouse model to analyse in vivo growth of LSCC cells following knockdown of hsa_circ_0042823.

RESULTS

Compared with normal human bronchial epithelial cells (HBECs), hsa_circ_0042823 was highly expressed in the LSCC cell lines (AMC-HN-8 and TU686). Further studies demonstrated that hsa_circ_0042823 interacted with miR-877-5p, and FOXM1 was the target of miR-877-5p. Hsa_circ_0042823 promoted the expression of FOXM1 via its ceRNA activity on miR-877-5p. Hsa_circ_0042823 overexpression promoted proliferation, migration and invasion of AMC-HN-8 cells through regulating miR-877-5p/FOXM1 axis. Additionally, inhibition of hsa_circ_0042823 inhibited growth of LSCC in vivo via miR-877-5p/FOXM1 axis.

CONCLUSIONS

Hsa_circ_0042823/miR-877-5p/FOXM1 axis participates in the progression of LSCC. This work demonstrates that hsa_circ_0042823 accelerates cancer progression by regulating miR-877-5p/FOXM1 axis in LSCC. Therefore, this study may provide new insights into the pathogenesis of LSCC.KEY MESSAGESHsa_circ_0042823 promotes FOXM1 expression by sponging miR-877-5p.Hsa_circ_0042823 promotes proliferation, migration, invasion of LSCC cells.Hsa_circ_0042823 knockdown inhibits tumour growth of LSCC via miR-877-5p/FOXM1 axis.

Competitive Endogenous RNA Landscape in Epstein-Barr Virus Associated Nasopharyngeal Carcinoma

Non-coding RNAs have been shown to play important regulatory roles, notably in cancer development. In this study, we investigated the role of microRNAs and circular RNAs in Nasopharyngeal Carcinoma (NPC) by constructing a circRNA-miRNA-mRNA co-expression network and performing differential expression analysis on mRNAs, miRNAs, and circRNAs. Specifically, the Epstein-Barr virus (EBV) infection has been found to be an important risk factor for NPC, and potential pathological differences may exist for EBV+ and EBV- subtypes of NPC. By comparing the expression profile of non-cancerous immortalized nasopharyngeal epithelial cell line and NPC cell lines, we identified differentially expressed coding and non-coding RNAs across three groups of comparison: cancer vs. non-cancer, EBV+ vs. EBV- NPC, and metastatic vs. non-metastatic NPC. We constructed a ceRNA network composed of mRNAs, miRNAs, and circRNAs, leveraging co-expression and miRNA target prediction tools. Within the network, we identified the regulatory ceRNAs of CDKN1B, ZNF302, ZNF268, and RPGR. These differentially expressed axis, along with other miRNA-circRNA pairs we identified through our analysis, helps elucidate the genetic and epigenetic changes central to NPC progression, and the differences between EBV+ and EBV- NPC.

CircPTK2 (hsa_circ_0003221) Contributes to Laryngeal Squamous Cell Carcinoma by the miR-1278/YAP1 Axis

Laryngeal cancer accounts for 20% of all head and neck malignancies. Laryngeal squamous cell carcinoma (LSCC) is the most common type of laryngeal cancer and is characterized by squamous differentiation, a high mortality rate, and poor prognosis. Accumulating studies have indicated that circular RNAs (circRNAs) are critical regulators in many cancers. CircPTK2 exerts an important regulatory role in several cancers. In this study, we aimed to elucidate the function of circPTK2 (hsa_circ_0003221) in LSCC. Through a series of investigations, we discovered that circPTK2 was significantly upregulated in LSCC tissues cells. Functionally, cell counting kit-8 (CCK-8) and flow cytometry analyses revealed that knockdown of circPTK2 suppressed LSCC cell viability and the cell cycle while promoting cell apoptosis. Notably, silencing circPTK2 inhibited tumor growth in vivo. Mechanistically, circPTK2 functioned as a molecular sponge of miR-1278 to upregulate YAP1 expression in LSCC cells. Moreover, YAP1 knockdown inhibited malignant phenotypes of LSCC cells. The rescue experiments showed that YAP1 overexpression reversed the effects of circPTK2 on LSCC cells. Therefore, we concluded that circPTK2 facilitates LSCC progression through the miR-1278/YAP1 axis.

GOLM1 Drives Colorectal Cancer Metastasis by Regulating Myeloid-derived Suppressor Cells

Colorectal cancer (CRC) is the most common digestive neoplasms worldwide, metastasis and recurrence still account for the leading cause for the high mortality rate, but the exact mechanisms remain unclear. More and more evidence has indicated that the deregulation of GOLM1 plays a crucial role in cancer progression. Here, we reported a novel role of GOLM1 in promoting CRC metastasis. In this study, the expression of GOLM1 was detected in human CRC cohort. The function of GOLM1 in CRC metastasis was analyzed by in vivo cecum orthotopic model. We found that the expression of GOLM1 was significantly increased in CRC tissues than adjacent nontumor. Overexpression GOLM1 can promote CRC immune escape and metastasis by recruiting of myeloid-derived suppressor cells (MDSCs) at the same time. PF-04136309, a small molecule and specific inhibitor of CCR2 can largely suppressed GOLM1-mediated CRC metastasis. These results suggest that GOLM1 can promote CRC metastasis and is a prognostic biomarker in human CRC.

CircRNAs: a family number of miRNA regulatory transcriptome in laryngeal carcinoma

Laryngeal carcinoma (LC) is a common head and neck cancer, which is the result of mutational changes due to gene dysregulation and etiological factors such as tobacco and smoking. A large number of patients received a poor prognosis due to diagnosis at an advanced stage. This highlights the need for definitive, early, and efficient diagnoses. With rapid development of high‐throughput sequencing, circular RNA (circRNA) has been reported to play a pivotal role in cancer. CircRNA functions as a microRNA (miRNA) sponge in the regulation of mRNA expression, forming circRNA‐miRNA regulatory axis. In this review, we described the axis in LC. The result indicated that CDR1as, hsa_circ_0042823, hsa_circ_0023028, circPARD3, hsa_circ_103862, hsa_circ_0000218, circMYLK, circCORO1C, hsa_circ_100290, circ‐CCND1, hsa_circ_0057481, circFLAN, and circRASSF2 expressed higher in LC, whereas, hsa_circ_0036722 and hsa_circ_0042666 expressed lower. The circRNAs regulated the target genes by sponging miRNAs and contributed to the pathogenesis of LC.

The expression profile and clinical application value of hsa_circ_0016148 in head and neck squamous cell carcinoma

Background

Dysregulated circular RNAs (circRNAs) are involved in human cancers and may be used as biomarkers with the potential of clinical application. However, little is known regarding the mechanism of circRNAs and their clinical application value in head and neck squamous cell carcinoma (HNSCC).

Methods

In the current study, we established the profile of circRNAs in HNSCC using microarray and then measured the expression of hsa_circ_0016148 in 137 paired HNSCC tissues by qRT‐PCR technique, analyzed the relationship between hsa_circ_0016148 and clinicopathological data, and investigated its diagnostic and prognostic value. The hsa_circ_0016148‐miRNA‐mRNA interaction network was predicted and constructed by Cytoscape.

Results

Our study showed a circRNA expression profile and confirmed downregulated hsa_circ_0016148 in HNSCC tissues (p = 2.64E‐35). The hsa_circ_0016148 expression is remarkably correlated with lymph node metastasis (p = 0.001) and clinical stage (p = 0.029). Then, the area under the receiver characteristic curve (AUC) was 0.912 with 92% of sensitivity and 86.9% specificity, respectively. Besides, our study demonstrated that lower‐expressed hsa_circ_0016148 could independently predict poorer overall survival of HNSCC patients (hazard ratio [HR] = 0.456; 95% confidence interval [CI] = 0.265–0.784; p = 0.005). The hsa_circ_0016148‐miRNA‐mRNA interaction network was constructed, which included a total of nine targeted miRNAs.

Conclusion

Taken together, our results revealed that hsa_circ_0016148 might play a critical role in HNSCC tumorigenesis and may serve as an indicator with the potential of diagnosis and prognosis for HNSCC.

Hsa_circ_0006232 promotes laryngeal squamous cell cancer progression through FUS-mediated EZH2 stabilization

Laryngeal squamous cell cancer (LSCC) is one of the most common malignant tumors in head and neck tumors. Our previous study has revealed that hsa_circ_0006232 is abnormally expressed in LSCC. This study attempts to verify the biological role of hsa_circ_0006232 in LSCC. We found that compared with human bronchial epithelial cells, hsa_circ_0006232 was highly expressed in human LSCC cells (AMC-HN-8 and TU686). Moreover, hsa_circ_0006232 promoted proliferation, migration and invasion of AMC-HN-8 and TU686 cells. Hsa_circ_0006232 promoted the expression of enhancer of zeste homolog 2 (EZH2) and repressed the expression of phosphatase and tensin homolog deleted on chromosome 10 (PTEN). Fused in sarcoma (FUS) interacted with hsa_circ_0006232 and EZH2, and FUS promoted the stabilization of EZH2. Hsa_circ_0006232 inhibited PTEN by promoting FUS expression. Moreover, we constructed a tumor xenograft model by injection of AMC-HN-8 cells with hsa_circ_0006232 knockdown, and we found that hsa_circ_0006232 deficiency decreased tumor growth in mice. Hsa_circ_0006232 silencing repressed EZH2 expression and enhanced PTEN expression in tumor tissues. In conclusion, our data have demonstrated that Hsa_circ_0006232 promotes proliferation, migration and invasion of LSCC cells, and accelerates tumor growth of LSCC through FUS-mediated EZH2 stabilization. Thus, hsa_circ_0006232 may be a novel therapeutic target in LSCC treatment.

Circular RNA ABCB10 contributes to laryngeal squamous cell carcinoma (LSCC) progression by modulating the miR-588/CXCR4 axis

Laryngeal squamous cell carcinoma (LSCC) is a common head and neck cancer with a high metastasis and poor prognosis. Circular RNAs (circRNAs) are a type of non-coding RNAs (ncRNAs) with regulatory function and broadly participate in cancer development. However, the correlation of circular RNA ABCB10 (circABCB10) with LSCC remains unclear. Here, we were interested in the role of circABCB10 in the modulation of LSCC progression. Our data demonstrated that the depletion of circABCB10 significantly inhibited the proliferation and induced the apoptosis of LSCC cells. Meanwhile, circABCB10 knockdown was able to remarkably reduce the invasion and migration of LSCC cells. Mechanically, circABCB10 served as a sponge for microRNAs-588 (miR-588) and miR-588 could target and down-regulated chemokine receptor 4 (CXCR4) expression in LSCC cells. The overexpression of CXCR4 or miR-588 inhibitor could reverse circABCB10 depletion-attenuated malignant phenotypes of LSCC cells. Functionally, the depletion of circABCB10 alleviated the tumor growth of LSCC cells in the tumorigenicity analysis of nude mice. The CXCR4 expression was decreased while the miR-588 expression was enhanced by circABCB10 depletion in vivo. Thus, we concluded that circABCB10 was involved in the malignant progression of LSCC by regulating miR-588/CXCR4 axis. Our finding provides new insights into the mechanism of circRHOT1 contributing to the development of LSCC. CircABCB10 and miR-588 may be used as potential targets for the treatment of LSCC.

The circ_0032822 Promotes the Proliferation of Head and Neck Squamous Cell Carcinoma Cells Through miR-141/EF3 Signaling Axis

Head and neck squamous cell carcinoma (HNSCC) refers to an epithelial malignant tumor that originates in the head and neck, and over 600,000 new cases are reported every year, However, the overall prognosis is still poor due to local recurrence and distant metastasis after surgery. The circ_0032822 has been reported upregulated in human oral squamous cell carcinoma; however, the detailed function or mechanism remains unknown. In this study, we confirmed the upregulation of circ_0032822 in HNSCC tumor tissues. Functionally, the overexpression of circ_0032822 significantly promoted the proliferation of HNSCC cell lines along with the S phase arrest and reduced apoptosis, while downregulation of circ_0032822 has the opposite effect in vitro. Mechanistic analysis showed that circ_0032822 acted as a competing endogenous RNA of miR-141 to diminish the repressive effect of miR-141 on its target E2F3. In conclusion, we demonstrated that circ_0032822 functions as a tumor oncogene in HNSCC and that its function is regulated via the miR-141/E2F3 axis.

Cyclic RNA Circ_0000735 sponges miR-502-5p to promote bladder cancer cell proliferation and invasion and inhibit apoptosis

OBJECTIVE

The objective of this study was to investigate the effect on the proliferation, invasion, and apoptosis of bladder cancer cells through miR-502-5p of the Circ_0000735 circular RNA.

METHODS

Circ_0000735 and miR-502-5p expression of bladder cancer patients in malignant and paracancerous tissues was identified using qRT-PCR. Nucleoplasm isolation assay and RNase R enzymatic assay were used to classify Circ_0000735 subcellular origin and stability. Dual luciferase reporter assay and RIP assay were used to confirm Circ_0000735 and miR-502-5p targeting relationships. Cell proliferation, apoptosis, and invasion capacity were identified using CCK8, flow cytometry, and transwell assays. To confirm the effect of Circ_0000735 on tumorigenesis in nude mice, in vivo experiments were conducted.

RESULTS

Circ_0000735 expression was increased in bladder cancer tissues and cells compared with paraneoplastic tissues and normal cells, and miR-502-5p expression was reduced (both P<0.05). In the cytoplasm, Circ_0000735 was largely clustered and could not be digested by the RNase R enzyme, and ceRNA may play a role in bladder cancer cells. Circ_0000735 silencing prevented cell proliferation and invasion and facilitated apoptosis (all P<0.05). The incorporation of miR-502-5p inhibitor rescued the effect on bladder cancer cells of Circ_0000735 silencing. In vitro experiments showed that inhibition of Circ_0000735 expression was beneficial in suppressing tumorigenic ability in nude mice.

CONCLUSION

Circ_0000735 can adsorb miR-502-5p to promote bladder cancer cell proliferation and invasion and inhibit apoptosis. Circ_0000735 may be an effective molecular target for bladder cancer therapy.