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 [...].

A tumor microenvironment-associated circRNA predictor for tumor relapse and chemotherapy vulnerability in nasopharyngeal carcinoma.

Accurate risk stratification for patients with locoregionally advanced nasopharyngeal carcinoma (LA-NPC) is crucial for prognosis and treatment decisions. Here, we develop a tumor microenvironment-associated circular RNA (circRNA) signature that can stratify LA-NPC patients with different risks of relapse and vulnerability to induction chemotherapy (IC). Relapsed-related circRNAs are identified by comparing expression profiles between patients with and without relapse, followed by quantitative validation in the training cohort (n = 170). A nine-circRNA signature is constructed to classify patients into high-risk and low-risk groups. Low-risk patients have significantly favorable clinical survivals, which is validated in the internal (n = 170) and external (n = 150) cohorts. They are characterized by an immune-active microenvironment and can derive benefits from IC. Meanwhile, high-risk patients characterized with pro-relapse and DNA repair-associated features, are vulnerable to chemoresistance. Overall, the circRNA-based classifier serves as a reliable prognostic tool and might guide chemotherapy decisions for patients with LA-NPC.

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.

VIRMA promotes nasopharyngeal carcinoma, tumorigenesis, and metastasis by upregulation of E2F7 in an m6A-dependent manner.

The N6-methyladenosine (m6A) modification possesses new and essential roles in tumor initiation and progression by regulating mRNA biology. However, the role of aberrant m6A regulation in nasopharyngeal carcinoma (NPC) remains unclear. Here, through comprehensive analyses of NPC cohorts from the GEO database and our internal cohort, we identified that VIRMA, an m6A writer, is significantly upregulated in NPC and plays an essential role in tumorigenesis and metastasis of NPC, both in vitro and in vivo. High VIRMA expression served as a prognostic biomarker and was associated with poor outcomes in patients with NPC. Mechanistically, VIRMA mediated the m6A methylation of E2F7 3'-UTR, then IGF2BP2 bound, and maintained the stability of E2F7 mRNA. An integrative high-throughput sequencing approach revealed that E2F7 drives a unique transcriptome distinct from the classical E2F family in NPC, which functioned as an oncogenic transcriptional activator. E2F7 cooperated with CBFB-recruited RUNX1 in a non-canonical manner to transactivate ITGA2, ITGA5, and NTRK1, strengthening Akt signaling-induced tumor-promoting effect.

TRIM21 inhibits irradiation-induced mitochondrial DNA release and impairs antitumour immunity in nasopharyngeal carcinoma tumour models.

Although radiotherapy can promote antitumour immunity, the mechanisms underlying this phenomenon remain unclear. Here, we demonstrate that the expression of the E3 ubiquitin ligase, tumour cell-intrinsic tripartite motif-containing 21 (TRIM21) in tumours, is inversely associated with the response to radiation and CD8+ T cell-mediated antitumour immunity in nasopharyngeal carcinoma (NPC). Knockout of TRIM21 modulates the cGAS/STING cytosolic DNA sensing pathway, potentiates the antigen-presenting capacity of NPC cells, and activates cytotoxic T cell-mediated antitumour immunity in response to radiation. Mechanistically, TRIM21 promotes the degradation of the mitochondrial voltage-dependent anion-selective channel protein 2 (VDAC2) via K48-linked ubiquitination, which inhibits pore formation by VDAC2 oligomers for mitochondrial DNA (mtDNA) release, thereby inhibiting type-I interferon responses following radiation exposure. In patients with NPC, high TRIM21 expression was associated with poor prognosis and early tumour relapse after radiotherapy. Our findings reveal a critical role of TRIM21 in radiation-induced antitumour immunity, providing potential targets for improving the efficacy of radiotherapy in patients with NPC.

LINC00173 facilitates tumor progression by stimulating RAB1B-mediated PA2G4 and SDF4 secretion in nasopharyngeal carcinoma.

An increasing number of studies have found that long non-coding RNA (lncRNA) play important roles in driving the progression of nasopharyngeal carcinoma (NPC). Our microarray screening revealed that expression of the lncRNA long intergenic non-protein coding RNA 173 (LINC00173) was upregulated in NPC. However, its role and mechanism in NPC have not yet been elucidated. In this study, we demonstrate that high LINC00173 expression indicated a poor prognosis in NPC patients. Knockdown of LINC00173 significantly inhibited NPC cell proliferation, migration and invasion in vitro. Mechanistically, LINC00173 interacted and colocalized with Ras-related protein Rab-1B (RAB1B) in the cytoplasm, but the modulation of LINC00173 expression did not affect the expression of RAB1B at either the mRNA or protein levels. Instead, relying on the stimulation of RAB1B, LINC00173 could facilitate the extracellular secretion of proliferation-associated 2G4 (PA2G4) and stromal cell-derived factor 4 (SDF4; also known as 45-kDa calcium-binding protein) proteins, and knockdown of these proteins could reverse the NPC aggressive phenotype induced by LINC00173 overexpression. Moreover, in vivo LINC00173-knockdown models exhibited a marked slowdown in tumor growth and a significant reduction in lymph node and lung metastases. In summary, LINC00173 serves as a crucial driver for NPC progression, and the LINC00173-RAB1B-PA2G4/SDF4 axis might provide a potential therapeutic target for NPC patients.

Chemotherapy-Induced Senescence Reprogramming Promotes Nasopharyngeal Carcinoma Metastasis by circRNA-Mediated PKR Activation.

Senescence is associated with tumor metastasis and chemotherapy resistance, yet the mechanisms remain elusive. Here, it is identified that nasopharyngeal carcinoma (NPC) patients who developed distant metastasis are characterized by senescence phenotypes, in which circWDR37 is a key regulator. CircWDR37 deficiency limits cisplatin or gemcitabine-induced senescent NPC cells from proliferation, migration, and invasion. Mechanistically, circWDR37 binds to and dimerizes double-stranded RNA-activated protein kinase R (PKR) to initiate PKR autophosphorylation and activation. Independent of its kinase activity, phosphorylated PKR induces I-kappaB kinase beta (IKKß) phosphorylation, binds to and releases RELA from NF-κB inhibitor alpha (IκBα) to trigger nuclear factor kappa B (NF-κB) activation, thereby stimulating cyclin D1 (CCND1) and senescence-associated secretory phenotype component gene transcription in a circWDR37-dependent manner. Low circWDR37 levels correlate with chemotherapy response and favorable survival in NPC patients treated with gemcitabine or cisplatin induction chemotherapy. This study uncovers a new mechanism of circWDR37 activated PKR in senescence-driven metastasis and provides appealing therapeutic targets in NPC.

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.

Association of Intratumoral Microbiota With Prognosis in Patients With Nasopharyngeal Carcinoma From 2 Hospitals in China.

Importance: Microbiota-tumor interactions have qualified microbiota as a promising prognostic biomarker in various types of cancers. Although the nasopharynx acts as a crucial niche of the upper respiratory tract microbiome, whether the intratumoral microbiota exists and its clinical significance in nasopharyngeal carcinoma (NPC) remain uncertain. Objective: To evaluate the clinical significance of intratumoral microbiota for individual prognostication in patients with NPC. Design, Setting, and Participants: This retrospective cohort study included NPC biopsy samples from 2 hospitals: Sun Yat-sen University Cancer Center (Guangzhou, China) and Zhejiang Cancer Hospital (Hangzhou, China) between January 2004 and November 2016, with follow-up through November 2020. A total of 802 patients were included according to the following criteria: with histologically proven NPC, without distant metastasis at initial diagnosis, had not received antitumor treatment before biopsy sampling, aged between 18 and 70 years, with complete medical records and regular follow-up, without a history of cancer, and successfully extracted enough DNA for experiments. Main Outcomes and Measures: The primary end point was disease-free survival, and the secondary end points included distant metastasis-free survival and overall survival. To assess the existence and load of intratumoral microbiota in 96 patients with NPC with or without tumor relapse, 16S rRNA sequencing and quantitative polymerase chain reaction were used. The associations between intratumoral bacterial load and clinical outcome were evaluated in 241 fresh-frozen NPC samples (training cohort) and validated in paraffin-embedded NPC samples of internal (n = 233) and external (n = 232) validation cohorts. Metagenomic and transcriptome analyses were performed to ascertain the origin and underlying mechanism of intratumoral bacteria. Results: A total of 802 patients with NPC (mean [SD] age, 46.2 [10.6] years; 594 [74.1%] male) were enrolled. Microbiota presented within NPC tumor tissues, among which Corynebacterium and Staphylococcus predominated. Patients with a high bacterial load in the training cohort had inferior rates of disease-free survival (hazard ratio [HR], 2.90; 95% CI, 1.72-4.90; P < .001), distant metastasis-free survival (HR, 3.18; 95% CI, 1.58-6.39; P < .001), and overall survival (HR, 3.41; 95% CI, 1.90-6.11, P < .001) than those with a low bacterial load, a finding that was validated by the internal and external validation cohorts. Single-nucleotide variant analysis revealed that the nasopharyngeal microbiota was the main origin of NPC intratumoral bacteria. Transcriptome and digital pathology analyses demonstrated that a higher intratumoral bacterial load was negatively associated with T-lymphocyte infiltration. Conclusions and Relevance: Intratumoral bacterial load was a robust prognostic tool for patients with NPC in this cohort study, indicating potential guidance for treatment decisions in patients at different levels of risk of malignant progression.

A lncRNA signature associated with tumor immune heterogeneity predicts distant metastasis in locoregionally advanced nasopharyngeal carcinoma.

Increasing evidence has revealed the roles of long noncoding RNAs (lncRNAs) as tumor biomarkers. Here, we introduce an immune-associated nine-lncRNA signature for predicting distant metastasis in locoregionally advanced nasopharyngeal carcinoma (LA-NPC). The nine lncRNAs are identified through microarray profiling, followed by RT-qPCR validation and selection using a machine learning method in the training cohort (n = 177). This nine-lncRNA signature classifies patients into high and low risk groups, which have significantly different distant metastasis-free survival. Validations in the Guangzhou internal (n = 177) and Guilin external (n = 150) cohorts yield similar results, confirming that the signature is an independent risk factor for distant metastasis and outperforms anatomy-based metrics in identifying patients with high metastatic risk. Integrative analyses show that this nine-lncRNA signature correlates with immune activity and lymphocyte infiltration, which is validated by digital pathology. Our results suggest that the immune-associated nine-lncRNA signature can serve as a promising biomarker for metastasis prediction in LA-NPC.

Expression Profiles and Prognostic Value of Multiple Inhibitory Checkpoints in Head and Neck Lymphoepithelioma-Like Carcinoma.

Background: Inhibitory checkpoints are promising antitumor targets and predictive biomarkers in a variety of cancers. We aimed to identify the expression levels and prognostic value of multiple inhibitory checkpoints supported by preclinical and clinical evidence in head and neck lymphoepithelioma-like carcinoma (HNLELC). Methods: The expression of seven inhibitory checkpoints were evaluated in the tumor nest (TN) and tumor stroma (TS) of 102 HNLELC specimens using immunohistochemistry and digital pathology, and an inhibitory checkpoint-based signature (ICS) was subsequently constructed using the LASSO Cox regression model. Results: PD-L1, B7H3, and IDO-1 were mostly expressed in the TN, with median H-score of TN vs TS: 63.6 vs 14.6; 8.1 vs 1.0; 61.5 vs 34.7 (all P < 0.001), whereas PD-1, TIM-3, LAG-3, and VISTA were mainly observed in the TS, with median H-score of TN vs TS: 0.2 vs 12.4, 3.4 vs 7.1, 6.2 vs 11.9, 16.4 vs 47.2 (all P < 0.001), respectively. The most common simultaneously expressed combinations consisted of PD-L1 + B7H3 + IDO-1 + TIM-3 + LAG-3 + VISTA and B7H3 + IDO-1 + TIM-3 + LAG-3 in the TN (both occurring in 8.8% of patients) and PD-L1 + B7H3 + IDO-1 in the TS (4.9%). In addition, high-ICS patients had shorter 5-year disease-free (40.6% vs 81.7%; P < 0.001), regional recurrence-free (63.5% vs 88.2%; P = 0.003), and overall survival (73.5% vs 92.9%; P = 0.006) than low-ICS patients. Multivariate analysis revealed that ICS represented an independent predictor, which could significantly complement the predictive performance of TNM stage for 3-year (AUC 0.724 vs 0.619, P = 0.014), 5-year (AUC 0.727 vs 0.640, P = 0.056), and 10-year disease-free survival (AUC 0.815 vs 0.709, P = 0.023). Conclusions: The expression of inhibitory checkpoints and ICS classifier may increase the prognostic value of the TNM staging system and guide the rational design of personalized inhibitory checkpoint blockade therapy in HNLELC.

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.

AR-induced long non-coding RNA LINC01503 facilitates proliferation and metastasis via the SFPQ-FOSL1 axis in nasopharyngeal carcinoma.

Increasing evidence indicates that long non-coding RNAs (lncRNAs) play vital roles in the tumorigenesis and progression of cancers. However, the functions and regulatory mechanisms of lncRNAs in nasopharyngeal carcinoma (NPC) are still largely unknown. Our previous lncRNA expression profiles identified that LINC01503 was overexpressed in NPC. Here, we verified that LINC01503 was highly expressed in NPC and correlated with poor prognosis. LINC01503 promoted NPC cell proliferation, migration, and invasion in vitro, and facilitated tumor growth and metastasis in vivo. Mechanistically, LINC01503 recruited splicing factor proline-and glutamine-rich (SFPQ) to activate Fos like 1 (FOSL1) transcription, and ectopic expression of FOSL1 reversed the suppressive effect of LINC01503 knockdown on NPC progression. Moreover, androgen receptor (AR)-mediated transcription activation was responsible for the overexpression of LINC01503, and AR ligand-dependent cell growth, migration, and invasion in NPC cells. Taken together, our findings reveal that AR-induced LINC01503 can promote NPC progression through the SFPQ-FOSL1 axis, which represents a novel prognostic biomarker and therapeutic target for NPC patients.

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.

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.