Correction: Zhao et al. Hypermethylation of UCHL1 Promotes Metastasis of Nasopharyngeal Carcinoma by Suppressing Degradation of Cortactin (CTTN). Cells 2020, 9, 559.

In the original publication [...].

Erratum: Long non-coding RNA DANCR stabilizes HIF-1α and promotes metastasis by interacting with NF90/NF45 complex in nasopharyngeal carcinoma: Erratum.

[This corrects the article DOI: 10.7150/thno.28538.].

m6A-enriched lncRNA LINC00839 promotes tumor progression by enhancing TAF15-mediated transcription of amine oxidase AOC1 in nasopharyngeal carcinoma.

Dysregulation of long noncoding RNAs (lncRNAs) contributes to tumorigenesis by modulating specific cancer-related pathways, but the roles of N6-methyladenosine (m6A)-enriched lncRNAs and underlying mechanisms remain elusive in nasopharyngeal carcinoma (NPC). Here, we reanalyzed the previous genome-wide analysis of lncRNA profiles in 18 pairs of NPC and normal tissues as well as in ten paired samples from NPC with or without post-treatment metastases. We discerned that an oncogenic m6A-enriched lncRNA, LINC00839, which was substantially upregulated in NPC and correlated with poor clinical prognosis, promoted NPC growth and metastasis both in vitro and in vivo. Mechanistically, by using RNA pull-down assay combined with mass spectrometry, we found that LINC00839 interacted directly with the transcription factor, TATA-box binding protein associated factor (TAF15). Besides, chromatin immunoprecipitation and dual-luciferase report assays demonstrated that LINC00839 coordinated the recruitment of TAF15 to the promoter region of amine oxidase copper-containing 1 (AOC1), which encodes a secreted glycoprotein playing vital roles in various cancers, thereby activating AOC1 transcription in trans. In this study, potential effects of AOC1 in NPC progression were first proposed. Moreover, ectopic expression of AOC1 partially rescued the inhibitory effect of downregulation of LINC00839 in NPC. Furthermore, we showed that silencing vir-like m6A methyltransferase-associated (VIRMA) and insulin-like growth factor 2 mRNA-binding proteins 1 (IGF2BP1) attenuated the expression level and RNA stability of LINC00839 in an m6A-dependent manner. Taken together, our study unveils a novel oncogenic VIRMA/IGF2BP1-LINC00839-TAF15-AOC1 axis and highlights the significance and prognostic value of LINC00839 expression in NPC carcinogenesis.

CircIPO7 Promotes Nasopharyngeal Carcinoma Metastasis and Cisplatin Chemoresistance by Facilitating YBX1 Nuclear Localization.

PURPOSE: Cisplatin-based chemotherapy effectively improves the distant-metastasis control in nasopharyngeal carcinoma (NPC), but approximately 30% of patients develop treatment failure due to chemoresistance. However, the underlying mechanisms remain poorly understood. EXPERIMENTAL DESIGN: Circular RNA (circRNA) sequencing data were used to identify metastasis-specific circRNAs and the expression of circIPO7 was validated in NPC tissues as well as NPC cell lines by qRT-PCR. The whole transcriptional profile upon circIPO7 knockdown was applied to explore the biological function and regulatory mechanism, which were further confirmed by in vitro and in vivo metastasis/chemosensitivity assays. We also evaluated the value of circIPO7 expression in predicting NPC metastasis and cisplatin chemoresistance by analyzing a cohort of 183 NPC patients. RESULTS: In this study, circIPO7, a novel circRNA, is found to be specifically overexpressed in NPC patients with distant metastasis. Knockdown of circIPO7 in NPC cells suppresses their metastasis and increases sensitivity to cisplatin treatment in vitro and in vivo. Mechanistically, circIPO7 binds to Y-box binding protein-1 (YBX1) protein in the cytoplasm and facilitates its phosphorylation at serine 102 (p-YBX1S102) by the kinase AKT, which further promotes YBX1 nuclear translocation and activates FGFR1, TNC, and NTRK1 transcription. Clinically, higher circIPO7 expression indicates unfavorable distant metastasis-free survival in NPC patients given cisplatin-based chemotherapy. CONCLUSIONS: Altogether, this study identifies oncogenic circIPO7 as a prognostic marker after cisplatin-based chemotherapy and as a potential therapeutic target for overcoming metastasis and chemoresistance in NPC.

Protein C receptor maintains cancer stem cell properties via activating lipid synthesis in nasopharyngeal carcinoma.

Metastasis and recurrence account for 95% of deaths from nasopharyngeal carcinoma (NPC). Cancer stem cells (CSCs) are regarded as one of the main reasons for tumor cell resistance to clinical therapy, and cancer metastasis or recurrence, while little is known about CSCs in NPC. The present study uncovers a subpopulation of cells labeled as CD45-EPCAM+PROCR+ in NPC biopsy samples that exhibit stem cell-like characteristics. A relatively low number of these cells initiate xenograft tumors in mice. Functional analysis reveals that protein C receptor (PROCR) not only serves as a stem cell marker in NPC, but also maintains tumor cells' stemness potential through regulating lipid metabolism and mitochondrial fission. Epistatic studies reveal that cAMP-protein kinase A stimulates Ca2+ release to manipulate lipid metabolism related genes' expression. Finally, in a cohort of 207 NPC samples, PROCR expression is correlated with tumor metastasis or recurrence, and predicts poor prognosis. These novel findings link PROCR labeled CSCs with lipid metabolism and mitochondrial plasticity, and provides new clinical target against metastatic or recurrent NPC.

USP44 regulates irradiation-induced DNA double-strand break repair and suppresses tumorigenesis in nasopharyngeal carcinoma.

Radiotherapy is the primary treatment for patients with nasopharyngeal carcinoma (NPC), and approximately 20% of patients experience treatment failure due to tumour radioresistance. However, the exact regulatory mechanism remains poorly understood. Here, we show that the deubiquitinase USP44 is hypermethylated in NPC, which results in its downregulation. USP44 enhances the sensitivity of NPC cells to radiotherapy in vitro and in vivo. USP44 recruits and stabilizes the E3 ubiquitin ligase TRIM25 by removing its K48-linked polyubiquitin chains at Lys439, which further facilitates the degradation of Ku80 and inhibits its recruitment to DNA double-strand breaks (DSBs), thus enhancing DNA damage and inhibiting DNA repair via non-homologous end joining (NHEJ). Knockout of TRIM25 reverses the radiotherapy sensitization effect of USP44. Clinically, low expression of USP44 indicates a poor prognosis and facilitates tumour relapse in NPC patients. This study suggests the USP44-TRIM25-Ku80 axis provides potential therapeutic targets for NPC patients.

A gene expression-based immune content predictor for survival and postoperative radiotherapy response in head and neck cancer.

The immune infiltration in the tumor microenvironment has been demonstrated to be relevant to radiotherapy response. Here, we sought to understand the immune infiltration in head and neck cancer (HNC) and evaluate its significance in predicting prognosis and radiotherapy response. Using RNA sequencing data of 522 retrospective head and neck squamous cell carcinomas (HNSCCs), we constructed an immune content score based on genes related to 6 prognostic infiltrating cell types. Unsupervised hallmark pathway clustering demonstrated an immune-related tumor cluster containing the immune content score. Patients with high immune content scores exhibited favorable overall survival and disease-free survival (DFS). Moreover, the immune content score was an independent prognostic factor for DFS in HNSCC. Interestingly, the immune content score was strongly associated with radiation response pathways. These results were also extended to nasopharyngeal carcinoma. Furthermore, patients in the low immune content score group significantly gained overall survival benefits from postoperative radiotherapy (PORT), whereas patients in the high immune content score group did not. Therefore, this study identifies the immune content score as a prognostic tool, which might have a potential association with PORT response, thereby facilitating outcome prediction and treatment decision in HNC.

A Gene-Expression Predictor for Efficacy of Induction Chemotherapy in Locoregionally Advanced Nasopharyngeal Carcinoma.

BACKGROUND: Induction chemotherapy (IC) followed by concurrent chemoradiotherapy is the mainstay treatment for patients with locoregionally advanced nasopharyngeal carcinoma. However, some patients obtain little benefit and experience unnecessary toxicities from IC. We intended to develop a gene-expression signature that can identify beneficiaries of IC. METHODS: We screened chemosensitivity-related genes by comparing gene-expression profiles of patients with short-term tumor response or nonresponse to IC (n = 95) using microarray analysis. Chemosensitivity-related genes were quantified by digital expression profiling in a training cohort (n = 342) to obtain a gene signature. We then validated this gene signature in the clinical trial cohort (n = 187) and an external independent cohort (n = 240). Tests of statistical significance are 2-sided. RESULTS: We identified 43 chemosensitivity-related genes associated with the short-term tumor response to IC. In the training cohort, a 6-gene signature was developed that was highly accurate at predicting the short-term tumor response to IC (area under the curve [AUC] = 0.87, sensitivity = 87.5%, specificity = 75.6%). We further found that IC conferred failure-free survival benefits only in patients in the benefit group (hazard ratio [HR] = 0.54, 95% confidence interval [CI] = 0.34 to 0.87; P = .01) and not on those in the no-benefit group (HR = 1.25, 95% CI = 0.62 to 2.51; P = .53). In the clinical trial cohort, the 6-gene signature was also highly accurate at predicting the tumor response (AUC = 0.82, sensitivity = 87.5%, specificity = 71.8%) and indicated failure-free survival benefits. In the external independent cohort, similar results were observed. CONCLUSIONS: The 6-gene signature can help select beneficiaries of IC and lay a foundation for a more individualized therapeutic strategy for locoregionally advanced nasopharyngeal carcinoma patients.

ZNF582 hypermethylation promotes metastasis of nasopharyngeal carcinoma by regulating the transcription of adhesion molecules Nectin-3 and NRXN3.

BACKGROUND: Epigenetic regulation plays an important role in the development and progression of nasopharyngeal carcinoma (NPC). However, the epigenetic mechanisms underlying NPC metastasis remains poorly understood. We aimed to find functional genes which regulate the metastasis of NPC and identify therapeutic targets for NPC treatment. METHODS: Bisulfite pyrosequencing was used to analyze zinc finger protein 582 (ZNF582) methylation in NPC tissues and cell lines. Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and Western blotting were used to determine the expression of ZNF582. In vitro and in vivo experiments were performed to evaluate the biological function of ZNF582 in NPC. ZNF582-targeting genes were identified by chromatin immunoprecipitation sequencing (ChIP-seq) and were confirmed by ChIP-qPCR and luciferase assay. RESULTS: ZNF582 promoter was hypermethylated in NPC, and both the mRNA and protein levels of ZNF582 were down-regulated in NPC tissues and cell lines. The restoration of ZNF582 inhibited NPC migration, invasion, and metastasis, while the knockdown of ZNF582 promoted NPC migration, invasion, and metastasis in vitro and in vivo. ZNF582 directly regulated the transcription and expression of adhesion molecules Nectin-3 and NRXN3. Both Nectin-3 and NRXN3 were identified as functional targets of ZNF582, and the restoration or abrogation of these genes reversed the tumor suppressor effect of ZNF582 in NPC metastasis. CONCLUSIONS: ZNF582 acts as a tumor suppressor gene in NPC by regulating the transcription and expression of adhesion molecules Nectin-3 and NRXN3, which may provide novel therapeutic targets for NPC treatment.

Plasma protein-based signature predicts distant metastasis and induction chemotherapy benefit in Nasopharyngeal Carcinoma.

Rationale: Currently, for locoregionally advanced nasopharyngeal carcinoma (LA-NPC), there is no effective blood-based method to predict distant metastasis. We aimed to detect plasma protein profiles to identify biomarkers that could distinguish patients with NPC who are at high risk of posttreatment distant metastasis. Methods: A high-throughput antibody array was initially applied to detect 1000 proteins in pretreatment plasma from 16 matched LA-NPC patients with or without distant metastasis after radical treatment. Differentially expressed proteins were further examined using a low-throughput array to construct a plasma protein-based signature for distant metastasis (PSDM) in a cohort of 226 patients. Results: Fifty circulating proteins were differentially expressed between metastatic and non-metastatic patients and 18 were proven to be strongly correlated with distant metastasis-free survival (DMFS) in NPC. A PSDM signature consisting of five proteins (SLAMF5, ESM-1, MMP-8, INSR, and Serpin A5) was established to assign patients with NPC into a high-risk group and a low-risk group. Patients in the high-risk group had shorter DMFS (P < 0.001), disease-free survival (DFS) (P < 0.001) and overall survival (OS) (P < 0.001). Moreover, the PSDM performed better than N stage and Epstein-Barr virus (EBV) DNA load at effectively identifying patients with NPC at high risk of metastasis. For patients in the high-risk group, induction chemotherapy significantly improved DMFS, DFS, and OS. Conclusions: The PSDM could be a useful liquid biopsy tool to effectively predict distant metastasis and the benefit of induction chemotherapy in patients with LA-NPC.

FNDC3B 3'-UTR shortening escapes from microRNA-mediated gene repression and promotes nasopharyngeal carcinoma progression.

Alternative polyadenylation (APA), which induces shortening of the 3'-UTR, is emerging as an important feature in cancer development and progression. Nevertheless, the effects and mechanisms of APA-induced 3'-UTR shortening in nasopharyngeal carcinoma (NPC) remain largely unclear. Fibronectin type III domain containing 3B (FNDC3B) tended to use proximal polyadenylation site and produce shorter 3'-UTR according to our previous sequencing study. Herein, we found that FNDC3B with shorter 3'-UTR could escape from miRNA-mediated gene repression, and caused its increased expression in NPC. Knocking down of FNDC3B inhibited NPC cell proliferation, migration, invasion, and metastasis in vitro and in vivo. Overexpression of FNDC3B, especially those with shorter 3'-UTR, promoted NPC progression. Furthermore, the mechanism study revealed that FNDC3B could bind to and stabilize myosin heavy chain 9 (MYH9) to activate the Wnt/ß-catenin signaling pathway. In addition, MYH9 could reverse the inhibitory effects of FNDC3B knockdown in NPC. Altogether, our results suggested that the 3'-UTR shortening of FNDC3B mRNA mediated its overexpression in NPC and promoted NPC progression by targeting MYH9. This newly identified FNDC3B-MYH9-Wnt/ß-catenin axis could represent potential targets for individualized treatment in NPC.

Hypermethylation of UCHL1 Promotes Metastasis of Nasopharyngeal Carcinoma by Suppressing Degradation of Cortactin (CTTN).

Epigenetic regulation plays an important role in the development and progression of nasopharyngeal carcinoma (NPC), but the epigenetic mechanisms underlying NPC metastasis remain poorly understood. Here, we demonstrate that hypermethylation of the UCHL1 promoter leads to its downregulation in NPC. Restoration of UCHL1 inhibited the migration and invasion of NPC cells in vitro and in vivo, and knockdown of UCHL1 promoted NPC cell migration and invasion in vitro and in vivo. Importantly, we found that UCHL1 interacts with CTTN, and may function as a ligase promoting CTTN degradation by increasing K48-linked ubiquitination of CTTN. Additionally, restoration of CTTN in NPC cells that overexpressed UCHL1 rescued UCHL1 suppressive effects on NPC cell migration and invasion, which indicated that CTTN is a functional target of UCHL1 in NPC. Our findings revealed that UCHL1 acts as a tumor suppressor gene in NPC and thus provided a novel therapeutic target for NPC treatment.

TRIM21-SERPINB5 aids GMPS repression to protect nasopharyngeal carcinoma cells from radiation-induced apoptosis.

BACKGROUND: The main strategy against nasopharyngeal carcinoma (NPC) is radiotherapy. However, radioresistance mediated recurrence is a leading clinical bottleneck in NPC. Revealing the mechanism of NPC radioresistance will help improve the therapeutic effect. METHODS: In this study, the role of TRIM21 (tripartite motif-containing 21) in NPC receiving ionizing radiation was firstly examined both in vivo and in vitro. Mass spectrometry analysis was performed to identify the downstream targets of TRIM21. NPC cells with TRIM21 or SERPINB5 (serpin family B member 5) overexpression or knockout were used to determine the epistatic relationship among SERPINB5, GMPS (guanine monophosphate synthase) and TRIM21. Flow cytometry, co-immunoprecipitation, western blot and immunofluorescence were employed to strengthen the results. Finally, immunohistochemistry using 4 radiosensitive and 8 radioresistent NPC patient samples was perform to examine the association between SERPINB5 or GMPS expression and patient radio-sensitivity. RESULTS: As an E3 ligase, TRIM21 was highly expressed in NPC. After ionizing radiation, TRIM21 repressed TP53 expression by mediating GMPS ubiquitination and degradation. Overexpression of TRIM21 protected NPC cells from radiation mediated cell apoptosis in vitro and in vivo. Further analysis revealed that TRIM21 mediated GMPS repression was dependent on SERPINB5, and SERPINB5 served as an adaptor which prevented GMPS from entering into the nucleus and introduced TRIM21 for GMPS ubiquitination. Moreover, the in vitro and in vivo results validated the finding that SERPINB5 promoted NPC cell radioresistance, and the radioresistant patients had higher SERPINB5 expression. CONCLUSIONS: Overall, our data showed that TRIM21-SERPINB5-mediated GMPS degradation facilitated TP53 repression, which promoted the radioresistance of NPC cells. This novel working model related to TP53 suppression provided new insight into NPC radioresistence clinically.

Circular RNA CRIM1 functions as a ceRNA to promote nasopharyngeal carcinoma metastasis and docetaxel chemoresistance through upregulating FOXQ1.

BACKGROUND: Circular RNAs (circRNAs), a new type of noncoding RNA (ncRNA), have been identified as significant gene expression regulators and are involved in cancer progression. However, the roles of circRNAs in nasopharyngeal carcinoma (NPC) remain largely unknown. METHODS: Here, the expression profile of circRNAs in a pair of NPC cell lines with different metastatic abilities (S18 and S26 cells) was analyzed by RNA-sequencing. Quantitative reverse transcription PCR was used to detect the expression level of circCRIM1 in NPC cells and tissues. Then, function experiments in vitro and in vivo were performed to evaluate the effects of circCRIM1 on NPC metastasis and EMT. Mechanistically, RNA immunoprecipitation, luciferase reporter assay, pull-down assay with biotinylated miRNA, fluorescent in situ hybridization were performed to confirm the interaction between circCRIM1 and miR-422a in NPC. The clinical value of circCRIM1 was evaluated in NPC metastasis and chemosensitivity. RESULTS: We identified that circCRIM1 was upregulated in highly metastatic NPC cells. CircCRIM1 was also overexpressed in NPC tissues with distant metastasis, and its overexpression promoted NPC cell metastasis and EMT. Mechanistically, circCRIM1 competitively bound to miR-422a and prevented the suppressive effects of miR-422a on its target gene FOXQ1, which finally led to NPC metastasis, EMT and docetaxel chemoresistance. Furthermore, high circCRIM1 expression was associated with unfavorable survival in NPC patients. We established a prognostic model based on circCRIM1 expression and N stage that effectively predicted the risk of distant metastasis and treatment response to docetaxel-containing induction chemotherapy in NPC patients. CONCLUSIONS: Our findings reveal the critical role of circCRIM1 specifically in promoting NPC metastasis and chemoresistance via a ceRNA mechanism and provide an exploitable biomarker and therapeutic target for prognosis and treatment resistance in NPC patients.

Development and validation of an immune checkpoint-based signature to predict prognosis in nasopharyngeal carcinoma using computational pathology analysis.

BACKGROUND: Immunotherapy, especially immune checkpoint inhibition, has provided powerful tools against cancer. We aimed to detect the expression of common immune checkpoints and evaluate their prognostic values in nasopharyngeal carcinoma (NPC). METHODS: The expression of 9 immune checkpoints consistent with 13 features was detected in the training cohort (n = 208) by immunohistochemistry and quantified by computational pathology. Then, the LASSO cox regression model was used to construct an immune checkpoint-based signature (ICS), which was validated in a validation cohort containing 125 patients. RESULTS: High positive expression of PD-L1 and B7-H4 was observed in tumour cells (TCs), whereas PD-L1, B7-H3, B7-H4, IDO-1, VISTA, ICOS and OX40 were highly expressed in tumour-associated immune cells (TAICs). Eight of the 13 immune features were associated with patient overall survival, and an ICS classifier consisting of 5 features (B7-H3TAIC, IDO-1TAIC, VISTATAIC, ICOSTAIC, and LAG3TAIC) was established. Patients with high-risk scores in the training cohort had shorter overall (P < 0.001), disease-free (P = 0.002), and distant metastasis-free survival (P = 0.004), which were confirmed in the validation cohort. Multivariate analysis revealed that the ICS classifier was an independent prognostic factor. A combination of the ICS classifier and TNM stage had better prognostic value than the TNM stage alone. In addition, the ICS classifier was significantly associated with survivals in patients with high EBV-DNA load. CONCLUSIONS: We determined the expression status of nine immune checkpoints consistent with 13 features in NPC and further constructed an ICS prognostic model, which might add prognostic value to the TNM staging system.

NFAT1 Hypermethylation Promotes Epithelial-Mesenchymal Transition and Metastasis in Nasopharyngeal Carcinoma by Activating ITGA6 Transcription.

DNA methylation is an important epigenetic change in carcinogenesis. However, the function and mechanism of DNA methylation dysregulation in nasopharyngeal carcinoma (NPC) is still largely unclear. Our previous genome-wide microarray data showed that NFAT1 is one of the most hypermethylated transcription factor genes in NPC tissues. Here, we found that NFAT1 hypermethylation contributes to its down-regulation in NPC. NFAT1 overexpression inhibited cell migration, invasion, and epithelial-mesenchymal transition in vitro and tumor metastasis in vivo. We further established that the tumor suppressor effect of NFAT1 is mediated by its inactivation of ITGA6 transcription. Our findings suggest the significance of activating NFAT1/ITGA6 signaling in aggressive NPC, defining a novel critical signaling mechanism that drives NPC invasion and metastasis and providing a novel target for future personalized therapy.

EZH2-DNMT1-mediated epigenetic silencing of miR-142-3p promotes metastasis through targeting ZEB2 in nasopharyngeal carcinoma.

Human nasopharyngeal carcinoma (NPC) has the highest metastatic rate in head and neck. However, the mechanisms underlying NPC metastasis remain unclear. Here using propensity-score-matched miRNA microarray analysis, miR-142-3p is identified to be the most correlated with distant-metastasis-free survival and downregulated in paraffin-embedded NPC with distant metastasis, which is validated in both internal cohort and external GEO dataset from Canada. miR-142 locus hypermethylation was observed and found to be associated with miR-142-3p downregulation in metastatic NPC. Furthermore, miR-142-3p was epigenetically silenced by EZH2-recruited DNMT1 and suppressed NPC cell metastasis and EMT. Intersecting PCR array gene profiling with bioinformatic prediction, we identify ZEB2 as a direct and functional target of miR-142-3p in NPC. Reversal of miR-142-3p silencing efficiently suppresses NPC cell invasion and metastasis. Moreover, epigenetic miR-142 hypermethylation is correlated with unfavorable prognosis in both training and validation cohorts. This study identifies miR-142-3p as a key suppressive regulator in NPC metastasis and reveals a DNMT1-mediated epigenetic mechanism for miR-142-3p silencing, providing a potential prognostic marker and therapeutic target to combat NPC metastasis.

Hypermethylation of SHISA3 Promotes Nasopharyngeal Carcinoma Metastasis by Reducing SGSM1 Stability.

Altered DNA methylation is a key feature of cancer, and aberrant methylation is important in nasopharyngeal carcinoma (NPC) development. However, the methylation mechanisms underlying metastasis of NPC remain unclear. Analyzing data from public databases and conducting our own experiments, we report here that promoter hypermethylation of SHISA3 is common and contributes to the downregulation of this gene in many types of tumors, including NPC. SHISA3 suppressed NPC cell invasion and metastasis in vitro and in vivo by impeding the E3 ubiquitin ligase tripartite motif containing 21 (TRIM21)-mediated ubiquitination and degradation small G protein signaling modulator 1 (SGSM1) and by inhibiting the MAPK pathway activation. Silencing SGSM1 abrogated the inhibitory effect of SHISA3 on NPC cell migration and invasion. This newly identified SHISA3-TRIM21-SGSM1 axis could be a novel therapeutic target in NPC. SIGNIFICANCE: These findings highlight the mechanism by which a newly identified tumor suppressor SHISA3 suppresses invasion and metastasis of nasopharyngeal carcinoma.