E2F6-Mediated Downregulation of MIR22HG Facilitates the Progression of Laryngocarcinoma by Targeting the miR-5000-3p/FBXW7 Axis

WTAP promotes laryngeal carcinoma cell progression by posttranscriptional activation of CTHRC1 in an m6A-YTHDF1-dependent way

Laryngeal carcinoma is one of the malignancies in the head and neck region with high incidence and mortality. Despite advances in therapeutic modalities, the 5-year survival rate remains low. Wilms tumor 1-associated protein (WTAP) has been reported to regulate cancer progression, however, its role and mechanism in regulating laryngeal carcinoma development remain unclear. In this study, the expressions of WTAP, collagen triple helix repeat containing 1 (CTHRC1), and YTH N6-methyladenosine RNA binding protein F1 (YTHDF1) and other molecules were detected by quantitative real-time polymerase chain reaction or western blotting. Cell viability and colony formation rate were determined by cell counting kit-8 assay and cell colony formation assay. Cell migration and invasion were investigated by transwell assay. The relationship between CTHRC1 and YTHDF1 was identified by RNA immunoprecipitation assay. The results showed that WTAP and CTHRC1 were upregulated in laryngeal carcinoma tissues and cells. WTAP or CTHRC1 silencing inhibited the proliferation, migration and invasion of laryngeal carcinoma cells. WTAP knockdown inhibited CTHRC1 mRNA stability by suppressing CTHRC1 m6A modification and YTHDF1 from recognizing CTHRC1 m6A sites. Moreover, CTHRC1 overexpression attenuated WTAP knockdown-mediated effects on laryngeal carcinoma cell phenotypes and the expression of β-catenin, C-myc and cyclinD1. Thus, WTAP facilitated CTHRC1 mRNA stability in an m6A-dependent manner to activate the Wnt/β-catenin pathway and promote laryngeal carcinoma cell malignant phenotypes.

Molecular insights and clinical implications for the tumor suppressor role of SCFFBXW7 E3 ubiquitin ligase

FBXW7 is one of the most well-characterized F-box proteins, serving as substrate receptor subunit of SKP1-CUL1-F-box (SCF) E3 ligase complexes. SCFFBXW7 is responsible for the degradation of various oncogenic proteins such as cyclin E, c-MYC, c-JUN, NOTCH, and MCL1. Therefore, FBXW7 functions largely as a major tumor suppressor. In keeping with this notion, FBXW7 gene mutations or downregulations have been found and reported in many types of malignant tumors, such as endometrial, colorectal, lung, and breast cancers, which facilitate the proliferation, invasion, migration, and drug resistance of cancer cells. Therefore, it is critical to review newly identified FBXW7 regulation and tumor suppressor function under physiological and pathological conditions to develop effective strategies for the treatment of FBXW7-altered cancers. Since a growing body of evidence has revealed the tumor-suppressive activity and role of FBXW7, here, we updated FBXW7 upstream and downstream signaling including FBXW7 ubiquitin substrates, the multi-level FBXW7 regulatory mechanisms, and dysregulation of FBXW7 in cancer, and discussed promising cancer therapies targeting FBXW7 regulators and downstream effectors, to provide a comprehensive picture of FBXW7 and facilitate the study in this field.

Comprehensive analysis reveals the involvement of hsa_circ_0037858/miR-5000-3p/FMR1 axis in malignant metastasis of clear cell renal cell carcinoma

Clear cell renal cell carcinoma (ccRCC) is a heterogenous tumor with high metastatic potential. Circular RNAs (circRNAs) play key roles in cancer initiation and progression. However, the knowledge of circRNA in ccRCC metastasis is still inadequate. In this study, a series of in silico analyses and experimental validation were employed. The differentially expressed circRNAs (DECs) between ccRCC and normal or metastatic ccRCC tissues were screened out using GEO2R. Hsa_circ_0037858 was identified as the most potential circRNA related to ccRCC metastasis, which was significantly downregulated in ccRCC compared with normal and was also markedly decreased in metastatic ccRCC compared with primary ccRCC. The structural pattern of hsa_circ_0037858 presented several microRNA response elements and four binding miRNAs of hsa_circ_0037858, consisting of miR-3064-5p, miR-6504-5p, miR-345-5p and miR-5000-3p, were predicted using CSCD and starBase. Among them, miR-5000-3p with high expression and statistical diagnostic value was considered as the most potential binding miRNA of hsa_circ_0037858. Then, protein-protein interaction analysis revealed a close linkage among the target genes of miR-5000-3p and the top 20 hub genes among them were identified. Based on node degree, MYC, RHOA, NCL, FMR1 and AGO1 were ranked as the top 5 hub genes. FMR1 was identified as the most potential downstream gene of hsa_circ_0037858/miR-5000-3p axis according to expression, prognosis and correlation analysis. Moreover, hsa_circ_0037858 suppressed in vitro metastasis and enhanced FMR1 expression in ccRCC, which could be markedly reversed by introduction of miR-5000-3p overexpression. Collectively, we elucidated a potential hsa_circ_0037858/miR-5000-3p/FMR1 axis involved in ccRCC metastasis.

FBXW7 attenuates tumor drug resistance and enhances the efficacy of immunotherapy

FBXW7 (F-box and WD repeat domain containing 7) is a critical subunit of the Skp1-Cullin1-F-box protein (SCF), acting as an E3 ubiquitin ligase by ubiquitinating targeted protein. Through degradation of its substrates, FBXW7 plays a pivotal role in drug resistance in tumor cells and shows the potential to rescue the sensitivity of cancer cells to drug treatment. This explains why patients with higher FBXW7 levels exhibit higher survival times and more favorable prognosis. Furthermore, FBXW7 has been demonstrated to enhance the efficacy of immunotherapy by targeting the degradation of specific proteins, as compared to the inactivated form of FBXW7. Additionally, other F-box proteins have also shown the ability to conquer drug resistance in certain cancers. Overall, this review aims to explore the function of FBXW7 and its specific effects on drug resistance in cancer cells.

LncRNA ZFAS1 promotes laryngeal cancer progression through RBFOX2-mediated MENA alternative splicing

Laryngeal cancer (LC) is the most common aggressive malignancy of the head and neck. LncRNA ZNFX1 antisense RNA 1 (ZFAS1) displays oncogenic properties in head and neck squamous cell carcinoma, but its regulatory role in laryngeal cancer progression remains obscure. Here, we found that ZFAS1 expression in laryngeal cancer tissues and cells was higher than that in adjacent normal tissues and normal nasopharyngeal epithelial cells. Highly expressed ZFAS1 was associated with advanced lymph node metastasis stages and clinical stages. ZFAS1 overexpression promoted LC cell proliferation, invasion, and N-cadherin and Vimentin expression, and suppressed E-cadherin expression. While ZFAS1 knockdown played an opposite role. Mechanistically, ZFAS1 stabilized RNA binding fox-1 homolog 2 (RBFOX2) protein expression by binding to RBFOX2, and RBFOX2 overexpression reversed the effect of ZFAS1 silence on cell functions. Moreover, highly expressed RBFOX2 led to skipping of MENA exon 11a and generating a pro-invasive isoform (MENA^INV ). MENA^INV overexpression effectively abolished the inhibitory effect of RBFOX2 knockdown on cell malignant progression. Furthermore, Hep2 cells infected with lentivirus-mediated ZFAS1 shRNA or negative control shRNA were subcutaneously injected into mice to assess the role of ZFAS1 in tumor growth. And the data showed that silencing ZFAS1 in vivo hindered xenograft tumor growth. In conclusion, silencing ZFAS1 alleviated malignant progression of laryngeal cancer cells and mouse xenograft tumor growth by regulating RBFOX2-mediated alternative splicing of MENA.

Potentials of lncRNA-miRNA-mRNA networks as biomarkers for laryngeal squamous cell carcinoma

Chemoresistance, radioresistance, and facile spreading of laryngeal squamous cell carcinoma (LSCC) make the practically clinical treatment invalid. Such dismal outcome mainly originates from the lack of effective biomarkers which are highly desirable to understand the pathogenesis of LSCC, and strives to find promising novel biomarkers to improve early screening, effective treatment, and prognosis evaluation in LSCC. Recently, long non-coding RNAs (lncRNAs), a kind of non-coding RNAs longer than 200 nucleotides, can participate in the process of tumorigenesis and progression through many regulatory modalities, such as epigenetic transcriptional regulation and post-transcriptional regulation. Meanwhile, microRNAs (miRNAs, miRs), essentially involved in the post-transcriptional regulation of gene expression, are aberrantly expressed in cancer-related genomic regions or susceptible sites. An increasing number of studies have shown that lncRNAs are important regulators of miRNAs expression in LSCC, and that miRNAs can also target to regulate the expression of lncRNAs, and they can target to regulate downstream messenger RNAs (mRNAs) transcriptionally or post-transcriptionally, thereby affecting various physiopathological processes of LSCC. Complex cross-regulatory networks existing among lncRNAs, miRNAs, and mRNAs can regulate the tumorigenesis and development of LSCC. Such networks may become promising biomarkers and potential therapeutic targets in the research field of LSCC. In this review, we mainly summarize the latest research progress on the regulatory relationships among lncRNAs, miRNAs, and downstream mRNAs, and highlight the potential applications of lncRNA-miRNA-mRNA regulatory networks as biomarkers for the early diagnosis, epithelial-mesenchymal transition (EMT) process, chemoresistance, radioresistance, and prognosis of LSCC, aiming to provide important clues for understanding the pathogenesis of LSCC and developing new diagnostic and therapeutic strategies.

Recent Insight on Regulations of FBXW7 and Its Role in Immunotherapy

SCF^FBXW7 E3 ubiquitin ligase complex is a crucial enzyme of the ubiquitin proteasome system that participates in variant activities of cell process, and its component FBXW7 (F-box and WD repeat domain–containing 7) is responsible for recognizing and binding to substrates. The expression of FBXW7 is controlled by multiple pathways at different levels. FBXW7 facilitates the maturity and function maintenance of immune cells via functioning as a mediator of ubiquitination-dependent degradation of substrate proteins. FBXW7 deficiency or mutation results in the growth disturbance and dysfunction of immune cell, leads to the resistance against immunotherapy, and participates in multiple illnesses. It is likely that FBXW7 coordinating with its regulators and substrates could offer potential targets to improve the sensitivity and effects of immunotherapy. Here, we review the mechanisms of the regulation on FBXW7 and its tumor suppression role in immune filed among various diseases (mostly cancers) to explore novel immune targets and treatments.

Long non-coding RNA MIR22HG suppresses cell proliferation and promotes apoptosis in prostate cancer cells by sponging microRNA-9-3p

The present study was designed to discuss long non-coding RNA (lncRNA) MIR22HG expression in prostate cancer and to address its effect on prostate cancer cells. MIR22HG and microRNA (miR)-9-3p expressions in prostate cancer cells were examined with the use of quantitative real-time PCR (qRT-PCR). Cell counting kit (CCK)-8, colony formation, and TUNEL were conducted to determine cell viability and apoptosis. Immunofluorescence was employed for the detection of Ki67 expression, and western blotting was applied for the examination of apoptosis-related proteins. The relationship of MIR22HG and miR-9-3p was verified employing luciferase reporter assay. Indeed, low MIR22HG expression was discovered in prostate cancer cells. Subsequently, in vitro loss-of-function studies revealed that MIR22HG overexpression suppressed cell proliferation but promoted cell apoptosis, accompanied with a reduction in Ki67 and Bcl-2 expressions, as well as an elevation in Bax and cleaved caspase 3 expressions. In addition, MIR22HG was identified as a sponge of miR-9-3p and the impacts of MIR22HG overexpression on cell proliferation and apoptosis were partly hindered by miR-9-3p overexpression. In summary, MIR22HG acts as an anticancer gene in prostate cancer via inhibiting cell proliferation and promoting apoptosis by sponging miR-9-3p. This article may provide a novel insight into the treatment of prostate cancer.

Long Noncoding RNA MALAT1 Promotes Laryngocarcinoma Development by Targeting miR-708-5p/BRD4 Axis to Regulate YAP1-Mediated Epithelial-Mesenchymal Transition

Objective. The objective of this study was to investigate whether long noncoding RNA Metastasis-Associated Lung Adenocarcinoma Transcript 1 (MALAT1) contributes to laryngocarcinoma development via regulating the Yes-associated protein 1- (YAP1-) mediated epithelial-mesenchymal transition (EMT) and the underlying mechanism. Methods. The effects of MALAT1 suppression and BET inhibitor JQ1 on the malignant phenotypes and cancer stem cell- (CSC-) like properties of laryngocarcinoma cells as well as the expression of bromodomain-containing protein 4 (BRD4), YAP1, and EMT markers were investigated. Moreover, the relationships between MALAT1 and miR-708-5p as well as between miR-708-5p and BRD4 were explored. Furthermore, whether MALAT1 regulated the malignant phenotypes of laryngocarcinoma cells via sponging miR-708-5p to target BRD4 was revealed by both in vitro and in vivo experiments. Results. MALAT1 suppression inhibited the malignant phenotypes of laryngocarcinoma cells, such as decreased proliferation, promoted apoptosis, suppressed migration, and inhibited the CSC properties. Suppression of MALAT1 increased miR-708-5p expression and decreased the expression of BRD4 and YAP1 and inhibited EMT. Moreover, there were target relationships between MALAT1 and miR-708-5p as well as between miR-708-5p and BRD4. miR-708-5p overexpression and MALAT1 suppression had synergistic inhibitory effects on the malignant phenotypes of laryngocarcinoma cells and the expression of BRD4, YAP1, and EMT. Furthermore, in vivo experiments confirmed that MALAT1/miR-708-5p regulated tumorigenicity by regulating BRD4 and YAP1-mediated EMT. Conclusions. Our results indicate that suppression of MALAT1 may inhibit laryngocarcinoma development by sponging miR-708-5p/BRD4 to regulate YAP1-mediated EMT. Targeting MALAT1/miR-708-5p/BRD4 axis may provide a promising therapeutic strategy for laryngocarcinoma.

Clinical significance of FBXW7 loss of function in human cancers

FBXW7 (F-Box and WD Repeat Domain Containing 7) (also referred to as FBW7 or hCDC4) is a component of the Skp1-Cdc53 / Cullin-F-box-protein complex (SCF/β-TrCP). As a member of the F-box protein family, FBXW7 serves a role in phosphorylation-dependent ubiquitination and proteasome degradation of oncoproteins that play critical role(s) in oncogenesis. FBXW7 affects many regulatory functions involved in cell survival, cell proliferation, tumor invasion, DNA damage repair, genomic instability and telomere biology. This thorough review of current literature details how FBXW7 expression and functions are regulated through multiple mechanisms and how that ultimately drives tumorigenesis in a wide array of cell types. The clinical significance of FBXW7 is highlighted by the fact that FBXW7 is frequently inactivated in human lung, colon, and hematopoietic cancers. The loss of FBXW7 can serve as an independent prognostic marker and is significantly correlated with the resistance of tumor cells to chemotherapeutic agents and poorer disease outcomes. Recent evidence shows that genetic mutation of FBXW7 differentially affects the degradation of specific cellular targets resulting in a distinct and specific pattern of activation/inactivation of cell signaling pathways. The clinical significance of FBXW7 mutations in the context of tumor development, progression, and resistance to therapies as well as opportunities for targeted therapies is discussed.

miR-5000-3p confers oxaliplatin resistance by targeting ubiquitin-specific peptidase 49 in colorectal cancer

Colorectal cancer (CRC) is the most common form of gastrointestinal malignancies. A growing number of reports focusing on oxaliplatin (OXA) resistance in CRC treatment have revealed that drug resistance is an urgent issue in clinical applications, especially for finding effective therapeutic targets. Recently, microRNAs (miRNAs) are reported to play a critical role in tumor progressions and multi-drug resistance. The main aim of this study is to establish whether miR-5000-3p is an oncogene that is resistant to OXA and further confirm its underlying regulatory role in CRC. The OXA-associated gene expression dataset in CRC cells was downloaded from Gene Expression Omnibus (GEO) database. Statistical software R was used for significance analysis of differentially expressed genes (DEGs) between OXA-resistant (OR)-CRC cells and CRC cells, and results indicated ubiquitin-specific peptidase 49 (USP49) was upregulated in OR-CRC cells. Luciferase reporter assay showed that USP49 was verified to act as a downstream target gene of miR-5000-3p. From the results of TCGA database, miR-5000-3p expression was upregulated and USP49 was downregulated in patients with CRC. The function of miR-5000-3p was detected using MTT assay, wound healing, Transwell, and flow cytometry assays. Moreover, through in vitro and in vivo experiments, miR-5000-3p expression was confirmed to be upregulated in CRC cells or OR-CRC cells comparing to normal cell lines. Molecular mechanism assays revealed that USP49 binds to the miR-5000-3p promoter to increase the expression of miR-5000-3p, resulting in cancer cells sensitized to OXA. To sum up, these results suggest that miR-5000-3p may be a novel biomarker involved in drug-resistance progression of CRC. Moreover, the drug-resistance mechanism of miR-5000-3p/USP49 axis provides new treatment strategies for CRC in clinical trials.

Long non-coding RNA MIR22HG inhibits glioma progression by downregulating microRNA-9/CPEB3

Glioma is one of the most common and aggressive malignant intracranial tumors worldwide. Recently, non-coding RNAs have been found to play critical roles in the development of glioma. However, the exact mechanisms have not been fully elucidated. In the present study, reverse transcription-quantitative PCR was used to determine the expression level of the long non-coding RNA MIR22HG and microRNA (miR)-9, while western blot analysis was used to detect the protein expression level of CPEB3. The potential binding sites were predicted using the StarBase v2.0 online tool and the hypothesis was verified using a luciferase reporter assay. A Cell Counting Kit-8 assay was used to assess cell viability, while wound healing and Matrigel assays were used to determine the migration and invasion ability of glioma cancer cells. The results showed that MIR22HG expression level was decreased but miR-9 expression level was elevated in glioma tissues and cell lines. Furthermore, MIR22HG was found to sponge miR-9, while CPEB3 was the direct target of miR-9 in the glioma cell line. Functionally, MIR22HG regulated the proliferation, invasion and migration of the glioma cell line by targeting miR-9. CPEB3 may be involved in the progression of the glioma cell line. Taken together, these findings confirmed that MIR22HG suppressed glioma development by inhibiting the miR-9/CPEB3 axis and provides a novel therapeutic strategy for glioma treatment.

LOXL1-AS1 contributes to the proliferation and migration of laryngocarcinoma cells through miR-589-5p/TRAF6 axis

Background

LOXL1-AS1 is a long non-coding RNA (lncRNA) that plays crucial roles in various cancers. However, the functional role of LOXL1-AS1 in laryngocarcinoma remains unclear. Thus we planned to probe into the function and underlying mechanism of LOXL1-AS1 in laryngocarcinoma.

Methods

Gene expression was evaluated in laryngocarcinoma cells using RT-qPCR. The ability of cell proliferation and migration was assessed by CCK8, colony formation, wound healing and transwell assays. The interaction among LOXL1-AS1, miR-589-5p and TRAF6 was detected by Ago2-RIP, RNA pull down and luciferase reporter assays.

Results

LOXL1-AS1 was overexpressed in laryngocarcinoma cells. Silencing of LOXL1-AS1 suppressed cell proliferation, migration and EMT in laryngocarcinoma. Moreover, miR-589-5p, the downstream of LOXL1-AS1, directly targeted TRAF6 in laryngocarcinoma. Importantly, LOXL1-AS1 augmented TRAF6 expression in laryngocarcinoma cells by sequestering miR-589-5p. Besides, miR-589-5p worked as a tumor-inhibitor while TRAF6 functioned as a tumor-facilitator in laryngocarcinoma. Of note, rescue experiments both in vitro and in vivo validated that LOXL1-AS1 aggravated the malignancy in laryngocarcinoma by targeting miR-589-5p/TRAF6 pathway.

Conclusions

LOXL1-AS1 promotes the proliferation and migration of laryngocarcinoma cells through absorbing miR-589-5p to upregulate TRAF6 expression.