Multiple Mechanisms Involving in Radioresistance of Nasopharyngeal Carcinoma

Failure patterns and individualized treatment plans of reirradiation for inoperable locally recurrent nasopharyngeal carcinoma

Re-irradiation with intensity-modulated radiotherapy (IMRT) remains the primary treatment modality for inoperable locally recurrent nasopharyngeal carcinoma (NPC). However, the rate of radiation-related late adverse effects is often substantially high. Therefore, we aimed to explore failure patterns and individualized treatment plans of re-irradiation for inoperable locally recurrent NPC. Ninety-seven patients who underwent IMRT were retrospectively analyzed. Sixty-two patients had clinical target volume of recurrence (rCTV) delineated, and thirty-five patients had only gross tumor volume of recurrence (rGTV) delineated. Twenty-nine patients developed second local failures after re-irradiation with IMRT (28 cases available). Among those patients, 64.3% (18/28) of patients and 35.7% (10/28) developed in-field or out-field, respectively. No statistical correlation was observed between target volume (rGTV or rCTV) and the local recurrence rate, local failure patterns, grade ≥ 3 toxicity, and survival. Multivariate analysis showed that recurrent T (rT) stage (HR 2.62, P = 0.019) and rGTV volume (HR 1.73, P = 0.037) were independent prognostic factors for overall survival (OS). Risk stratification based on rT stage and rGTV volume revealed that low risk group had a longer 3-year OS rate (66.7% vs. 23.4%), lower total grade ≥ 3 toxicity (P = 0.004), and lower re-radiation associated mortality rates (HR 0.45, P = 0.03) than high risk group. This study demonstrates that the delineation of rCTV may not be beneficial for re-irradiation using IMRT in locally recurrent NPC. Patients with low risk were most suitable for re-irradiation, with maximizing local salvage and minimizing radiation-related toxicities. More precise and individualized plans of re-irradiation are warranted.

Homeobox B2 promotes malignant behavior and contributes to the radioresistance of nasopharyngeal carcinoma by regulating forkhead box protein O1

Background: Nasopharyngeal carcinoma (NPC) is an epithelial tumor of the head and neck with heterogeneous racial and geographical distributions. Homeobox B2 (HOXB2) is a tumor promoter in many cancers. However, the biological role of HOXB2 in NPC has not been elucidated. Methods: Bioinformatics analysis was performed to identify the differentially expressed genes (DEGs) between samples of patients with radiosensitive and radioresistant NPC. qRT-PCR, western blotting and immunohistochemistry were used to detect the expression levels of the corresponding mRNA and proteins. Cell viability was detected by CCK-8 assay and colony-forming capability was evaluated using colony formation assays. Further, migration and invasion abilities were examined using wound-healing and transwell chamber assays, respectively. Cellular apoptosis after irradiation was assessed using flow cytometry and terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) staining. Results: HOXB2 was identified as a potential regulator of radioresistance in NPC. Our in vitro results indicate that HOXB2 overexpression (HOXB2-OE) promoted malignant behaviors including invasion, migration, proliferation, and inhibited the irradiation-induced apoptosis of NPC cells. Consistent with these results, HOXB2 knockdown (HOXB2-sh) exhibited the opposite trends in these biological activities. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that the DEGs were enriched in the FOXO signaling pathway. Mechanistically, western blotting showed that HOXB2-OE inhibited forkhead box protein O1 (FOXO1) expression in NPC cells. Thereafter, we transferred the FOXO1-OE plasmid to HOXB2-OE NPC cells and found that overexpression of FOXO1 reversed cell proliferation, migration, invasion, and radioresistance profiles promoted by HOXB2 overexpression. Conclusion: Our findings showed that HOXB2 acts as a tumor promoter in NPC, activating malignant behaviors and radioresistance of tumors via FOXO1 regulation. Moreover, the inactivation of HOXB2 or activation of FOXO1 are potential strategies to inhibit tumor progression and overcome radioresistance in NPC.

Ferroptosis-Related Genes Are Associated with Radioresistance and Immune Suppression in Head and Neck Cancer

Background: Ferroptosis is associated with tumor development; however, its contribution to radioresistant head and neck cancer (HNC) remains unclear. In this study, we used bioinformatics analysis and in vitro testing to explore ferroptosis-related genes associated with HNCs radiosensitivity. Materials and Methods: GSE9714, GSE90761, and The Cancer Genome Atlas (TCGA) datasets were searched to identify ferroptosis-related differentially expressed genes between radioresistant and radiosensitive HNCs or radiation-treated and nonradiation-treated HNCs. A protein-protein interaction analysis on identified hub genes was then performed. Receiver operating characteristic curves and Kaplan-Meier survival analysis were used to assess the diagnostic and prognostic potential of the hub genes. Cell counting kit-8, transwell assay, and flow cytometry were applied to examine the role of hub gene collagen type IV, alpha1 chain (COL4A1) on the proliferation, migration, invasion, and apoptosis of TU686 cells. Results: Hub genes MMP10, MMP1, COL4A1, IFI27, and INHBA showed diagnostic potential for HNC and were negatively correlated with overall survival and disease-free survival in the TCGA dataset. Also, IL-1B, IFI27, INHBA, and COL4A1 mRNA levels were significantly increased in TCGA patients with advanced clinical stages or receiving radiotherapy, whereas COL4A1, MMP10, and INHBA expressions were negatively correlated with immune infiltration. Furthermore, the knockdown of COL4A1 inhibited cell proliferation, migration, and invasion while promoting apoptosis in TU686 cells. Conclusion: Ferroptosis-related hub genes, such as COL4A1, are potential diagnostic and prognostic indicators as well as therapeutic targets for HNC.

Inhibition of MNK pathway sensitizes nasopharyngeal carcinoma to radiotherapy

Improving the clinical management of nasopharyngeal carcinoma (NPC) is an unmet need owing to the high incidence of treatment failure caused by radioresistance. In our study, we observed increased phosphorylation of translation initiation factor 4E (eIF4E), regulated by MAP kinase-interacting kinase (MNK), in NPC cells following irradiation treatment. Using siRNA to deplete MNK, we found that radiation-induced eIF4E phosphorylation was eliminated, NPC cell sensitivity to radiation was enhanced, and radioresistant NPC cell viability was reduced. Furthermore, we tested three pharmacological MNK inhibitors (eFT508, CGP57380, and cercosporamide) and found that they were effective against radioresistant NPC cells and synergized with irradiation. In-vivo experiments confirmed that eFT508, at a tolerable dose, inhibited the growth of radioresistant NPC and synergized with radiation in a radiosensitive NPC xenograft model. Our research highlights the activation of MNK-mediated survival mechanisms in NPC in response to radiotherapy and the potential of combining radiation with MNK inhibitors as a sensitizing strategy. Notably, eFT508 is currently being investigated in clinical trials for cancer treatment, and our findings may prompt the initiation of clinical trials using eFT508 in radioresistant NPC patients.

Depletion of SLC7A11 Sensitizes Nasopharyngeal Carcinoma Cells to Ionizing Radiation

BACKGROUND

Radiotherapy is the primary treatment choice for Nasopharyngeal Carcinoma (NPC). However, its efficacy is compromised due to radioresistance. Ferroptosis, a novel iron-dependent regulated cell death induced by Ionizing Radiation (IR), plays a role in promoting cancer cell death. Yet, the relationship between enhanced ferroptosis and increased sensitivity of NPC cells to IR remains poorly understood.

OBJECTIVE

This study aimed to explore the association between IR and ferroptosis in NPC, as well as the role of the ferroptosis repressor SLC7A11 in IR-treated NPC cells.

METHODS

CNE1 and HNE-2 NPC cells were subjected to IR treatment. We performed qPCR and western blotting to evaluate the expression of ferroptosis-related genes in both control and IR-treated NPC cells. Additionally, we used the MTT assay to measure the viability of these NPC cells. JC-1 and DCFH-DA staining were employed to assess mitochondrial membrane potential and Reactive Oxygen Species (ROS) levels in both control and IR-treated NPC cells. Furthermore, we examined the levels of Fe2+, Malondialdehyde (MDA), reduced Glutathione (GSH), and oxidized glutathione (GSSG) in these cells. Moreover, we depleted SLC7A11 in IR-treated NPC cells to investigate its impact on the ferroptosis of these cells.

RESULTS

IR upregulated the expression of ferroptosis-related genes, including SLC7A11, ACSL4, COX2, FTH1, and GPX4, in CNE1 and HNE-2 cells. IR treatment also resulted in decreased cell viability, disrupted mitochondrial membrane potential, increased ROS levels, altered glutathione levels, and elevated Fe2+ levels. Knockdown of SLC7A11 enhanced the sensitivity of NPC cells to IR.

CONCLUSION

IR may induce ferroptosis in NPC cells, and stimulating ferroptosis could potentially serve as a therapeutic strategy to enhance the efficacy of IR in treating NPC patients.

Radiation-sensitive genetic prognostic model identifies individuals at risk for radiation resistance in head and neck squamous cell carcinoma

BACKGROUND

The advantages of radiotherapy for head and neck squamous cell carcinoma (HNSCC) depend on the radiation sensitivity of the patient. Here, we established and verified radiological factor-related gene signature and built a prognostic risk model to predict whether radiotherapy would be beneficial.

METHODS

Data from The Cancer Genome Atlas, Gene Expression Omnibus, and RadAtlas databases were subjected to LASSO regression, univariate COX regression, and multivariate COX regression analyses to integrate genomic and clinical information from patients with HNSCC. HNSCC radiation-related prognostic genes were identified, and patients classified into high- and low-risk groups, based on risk scores. Variations in radiation sensitivity according to immunological microenvironment, functional pathways, and immunotherapy response were investigated. Finally, the expression of HNSCC radiation-related genes was verified by qRT-PCR.

RESULTS

We built a clinical risk prediction model comprising a 15-gene signature and used it to divide patients into two groups based on their susceptibility to radiation: radiation-sensitive and radiation-resistant. Overall survival was significantly greater in the radiation-sensitive than the radiation-resistant group. Further, our model was an independent predictor of radiotherapy response, outperforming other clinical parameters, and could be combined with tumor mutational burden, to identify the target population with good predictive value for prognosis at 1, 2, and 3 years. Additionally, the radiation-resistant group was more vulnerable to low levels of immune infiltration, which are significantly associated with DNA damage repair, hypoxia, and cell cycle regulation. Tumor Immune Dysfunction and Exclusion scores also suggested that the resistant group would respond less favorably to immunotherapy.

CONCLUSIONS

Our prognostic model based on a radiation-related gene signature has potential for application as a tool for risk stratification of radiation therapy for patients with HNSCC, helping to identify candidates for radiation therapy and overcome radiation resistance.

[Icaritin increases radiosensitivity of nasopharyngeal carcinoma cells by regulating iron death]

OBJECTIVE

To explore the radiosensitizing effect of icaritin on nasopharyngeal carcinoma (NPC) cells and the underlying mechanism.

METHODS

MTT assay and clonal formation assay were used to evaluate the effect of icaritin on proliferation of human NPC HONE1 and HNE1 cells. The effects of icaritin treatment, γ-ray radiation, or both on production of reactive oxygen species (ROS), cell cycle distribution and apoptosis of the NPC cells were assessed using flow cytometry. The expressions of DNA damage markers γ-H2AX, cycle-related proteins CDC25C, p-CDC25C and cyclin B1, and ferroptosis markers ACSL4 and GXP4 were detected using Western blotting. A nude mouse model bearing subcutaneous HONE1 cell xenograft was used to observe the effect of icaritin and radiation on tumor growth.

RESULTS

Icaritin dose-dependently inhibited the viability of the NPC cells and enhanced the inhibitory effect of radiation on cell proliferation. Flow cytometry and Western blotting showed that icaritin treatment prior to radiation significantly promoted ROS production and γ-H2AX expression in the NPC cells (P<0.001). Compared with radiation exposure alone, the combined treatment caused cell cycle arrest in G2 phase, down-regulated CDC25C and cyclin B1 expression, and up-regulated p-CDC25C expression in the cells (P<0.01), resulting also in increased cell apoptosis, enhanced expression of ferroptosis protein ACSL4 and lowered expression of GXP4 (P<0.001). In the tumor-bearing mice, icaritin treatment, compared with radiation alone, significantly reduced the tumor growth rate and decreased tumor weight (P<0.001).

CONCLUSION

Icaritin can enhance radiosensitivity of NPC cells both in vitro and in nude mice possibly by enhancing ROS production to promote iron death of the cells.

miR-128-3p increases the radiosensitivity in nasopharyngeal carcinoma via regulating vascular endothelial growth factor C

PURPOSE

This study aims to investigate the role of miR-128-3p in the radiosensitivity of nasopharyngeal carcinoma (NPC) and its underlying mechanism.

METHODS

6-10B cells were transfected with miR-128-3p mimic, pcDNA-VEGFC, and the corresponding negative control. C666-1 cells were transfected with miR-128-3p inhibitor, sh-VEGFC, and the corresponding negative control. RT-qPCR was used to determine the miR-128-3p and VEGFC mRNA expression level. Dual-luciferase assay was used to investigate the relationship between miR-128-3p and VEGFC. The protein levels of VEGFC, H2AX, γ-H2AX, p-P50, p-P65, p-IκB, and the apoptosis markers Bcl-2, caspase3, caspase9, and Bax were detected by Western blot. The proliferation activity was detected by CCK-8, and cell DNA damage was assessed by comet assay. The apoptosis rate was detected by flow cytometry. The growth of NPC in vivo was observed in mice through xenotransplantation. TUNEL staining was used to detect cell apoptosis in tumor tissues.

RESULTS

miR-128-3p was targeted and was negatively regulated with VEGFC. Overexpression of miR-128-3p or knockdown VEGFC significantly inhibited the proliferation of 6-10B and C666-1 cells, induced DNA damage and apoptosis and promoted the radiosensitivity of cells. Knocking down miR-128-3p or up-regulated VEGFC promoted the proliferation of C666-1 and 6-10B cells, reduced cell DNA damage and apoptosis, and enhanced cell resistance to radiotherapy. Overexpression of miR-128-3p reversed the effect of VEGFC on 6-10B cells and inhibited P50/P65/IKB signal pathway. In vivo, experiments in mice confirmed that miR-128-3p significantly inhibited NPC proliferation and promoted DNA damage and apoptosis by targeting VEGFC.

CONCLUSION

The miR-128-3p pathway is a novel therapy target to overcome radiation resistance in NPC.

Long noncoding RNA LINC00173 induces radioresistance in nasopharyngeal carcinoma via inhibiting CHK2/P53 pathway

Radiotherapy is the backbone of nasopharyngeal carcinoma (NPC), nearly 11-17% NPC patients suffered local relapse and 18-37% suffered distant metastasis mainly due to radioresistance. Therefore, the key of improving patients' survivals is to investigate the mechanism of radioresistance. In this study, we revealed that the expression level of long intergenic nonprotein coding RNA 173 (LINC00173) was significantly increased in the radioresistant NPC patients' tumour tissues compared with the radiosensitive patients by RNA-sequencing, which also predict poor prognosis in NPC. Overexpression of LINC00173 induced radioresistance of NPC cells in vitro and in vivo. Mechanistically, LINC00173 bound with checkpoint kinase 2 (CHK2) in nucleus, and impaired the irradiation-induced CHK2 phosphorylation, then suppressed the activation of P53 signalling pathway, which eventually inhibiting apoptosis and leading to radioresistance in NPC cells. In summary, LINC00173 decreases the occurrence of apoptosis through inhibiting the CHK2/P53 pathway, leads to NPC radioresistance and could be considered as a novel predictor and therapeutic target in NPC.

Tumor residue in patients with stage II-IVA nasopharyngeal carcinoma who received intensity-modulated radiation therapy: development and validation of a prediction nomogram integrating postradiotherapy plasma Epstein-Barr virus deoxyribonucleic acid, clinical stage, and radiotherapy dose

BACKGROUND

To develop and validate a predictive nomogram for tumor residue 3-6 months after treatment based on postradiotherapy plasma Epstein-Barr virus (EBV) deoxyribonucleic acid (DNA), clinical stage, and radiotherapy (RT) dose in patients with stage II-IVA nasopharyngeal carcinoma (NPC) treated with intensity-modulated radiation therapy (IMRT).

METHODS

In this retrospective study, 1050 eligible patients with stage II-IVA NPC, who completed curative IMRT and underwent pretreatment and postradiotherapy (-7 to +28 days after IMRT) EBV DNA testing, were enrolled from 2012 to 2017. The prognostic value of the residue was explored using Cox regression analysis in patients (n=1050). A nomogram for predicting tumor residues after 3-6 months was developed using logistic regression analyses in the development cohort (n=736) and validated in an internal cohort (n=314).

RESULTS

Tumor residue was an independent inferior prognostic factor for 5-year overall survival, progression-free survival, locoregional recurrence-free survival and distant metastasis-free survival (all P<0.001). A prediction nomogram based on postradiotherapy plasma EBV DNA level (0 vs. 1-499 vs. ≥500 copies/ml), clinical stage (II vs. III vs. IVA), and RT dose (68.00-69.96 vs. 70.00-74.00 Gy) estimated the probability of residue development. The nomogram showed better discrimination (area under the curve (AUC): 0.752) than either the clinical stage (0.659) or postradiotherapy EBV DNA level (0.627) alone in the development and validation cohorts (AUC: 0.728).

CONCLUSIONS

We developed and validated a nomogram model integrating clinical characteristics at the end of IMRT for predicting whether tumor will residue or not after 3-6 months. Thus, high-risk NPC patients who might benefit from immediate additional intervention could be identified by the model, and the probability of residue can be reduced in the future.

LncRNA CASC19 Enhances the Radioresistance of Nasopharyngeal Carcinoma by Regulating the miR-340-3p/FKBP5 Axis

Radioresistance remains a serious obstacle encountered in the radiotherapy of nasopharyngeal carcinoma (NPC). Both mRNAs and non-coding RNAs (ncRNAs), including long ncRNA (lncRNA) and microRNA (miRNA), play essential roles in radiosensitivity. However, the comprehensive expression profiles and competing endogenous RNA (ceRNA) regulatory networks among lncRNAs, miRNAs, and mRNAs in NPC radioresistance are still bewildering. In this study, we performed an RNA-sequencing (RNA-seq) assay in the radioresistant NPC cells CNE2R and its parental cells CNE2 to identify the differentially expressed lncRNAs, miRNAs, and mRNAs. The ceRNA networks containing lncRNAs, miRNAs, and mRNAs were predicted on the basis of the Pearson correlation coefficients and authoritative miRanda databases. In accordance with bioinformatic analysis of the data of the tandem mass tag (TMT) assay of CNE2R and CNE2 cells and the gene chip assay of radioresistant NPC samples in pre- and post-radiotherapy, the radioresistance-related signaling network of lncRNA CASC19, miR-340-3p, and FKBP5 was screened and further verified using an RT-qPCR assay. CASC19 was positively associated with FKBP5 expression while negatively correlated with miR-340-3p, and the target binding sites of CASC19/miR-340-3p and miR-340-3p/FKBP5 were confirmed using a dual-luciferase reporter assay. Moreover, using an mRFP-GFP-LC3 maker, it was found that autophagy contributed to the radioresistance of NPC. MiR-340-3p inhibition or FKBP5 overexpression could rescue the suppression of autophagy and radioresistance induced by CASC19 knockdown in CNE2R cells. In conclusion, the CASC19/miR-340-3p/FKBP5 network may be instrumental in regulating NPC radioresistance by enhancing autophagy, which provides potential new therapeutic targets for NPC.

OTUD4-mediated GSDME deubiquitination enhances radiosensitivity in nasopharyngeal carcinoma by inducing pyroptosis

BACKGROUND

Radioresistance is the primary cause of nasopharyngeal carcinoma (NPC) treatment failure. Previous studies have focused on the deficits in cellular apoptosis as a mechanism for radioresistance; however, additional potential death modes involved in modulating radiosensitivity of NPC have not been explored.

METHODS

Pyroptosis was assessed by phase-contrast imaging, LDH release assays, live cell imaging, and Western blotting. In vitro and in vivo assays were used to investigate the function of gasdermin E (GSDME) and ovarian tumor family deubiquitinase 4 (OTUD4). NPC tissues were analyzed using Western blotting, immunohistochemistry, and real-time PCR. The molecular mechanism was determined using immunoprecipitation assays and mass spectrometry.

RESULTS

Live cell imaging revealed that 40-75% of irradiation-induced dead NPC cells were pyroptotic cells. Furthermore, irradiation-induced pyroptosis is triggered by GSDME, which are cleaved by activated caspase-3 in the intrinsic mitochondrial pathway. Additionally, GSDME was significantly downregulated in radioresistant NPC specimens. Low GSDME expression was a predictor of worse prognosis and conferred NPC radioresistance both in vitro and in vivo. Mechanistically, OTUD4 deubiquitinated and stabilized GSDME, enhancing radiosensitivity of NPC cells by promoting pyroptosis. Clinically, OTUD4 was significantly correlated with GSDME in NPC biopsies, and patients with low expression of both OTUD4 and GSDME suffered the worst radiotherapy response and survival.

CONCLUSIONS

GSDME-dependent pyroptosis is a critical determinant of radiosensitivity in NPC, and is modulated by OTUD4 via deubiquitinating and stabilizing GSDME. These findings reveal a promising novel direction to investigate radioresistance and suggest potential therapeutic targets for sensitizing NPC to radiotherapy.

DPCPX induces Bim-dependent apoptosis in nasopharyngeal carcinoma cells

ADORA1 promotes tumor growth and development in multiple cancers. DPCPX (a selective adenosine A1 receptor antagonist), a specific ADORA1 antagonist, has shown antitumor effects in many cancer types. Nevertheless, the function of DPCPX in nasopharyngeal carcinoma (NPC) still remains to be unraveled. In this study, we investigated the functional role of DPCPX on NPC cells. We found that DPCPX promotes NPC cells growth inhibition. DPCPX induced Bim-dependent apoptosis in NPC cells irrespective of p53 status via the FoxO3a pathway following PI3K/AKT inhibition. Furthermore, DPCPX enhanced the antitumor effect of cisplatin, 5-FU and Paclitaxel in NPC. Xenograft experiment revealed that deficiency of Bim in vivo stalls apoptosis and antitumor activity of DPCPX. In conclusion, the PI3K/AKT/FoxO3a/Bim axis plays a critical role in the anticancer effects of DPCPX in NPC.

Clinical Characteristics and Predictive Outcomes of Recurrent Nasopharyngeal Carcinoma-A Lingering Pitfall of the Long Latency

Purpose: To investigate the clinical characteristics, risk factors, and clinical outcomes of long-latent recurrence (>five years) of nasopharyngeal carcinoma (NPC). Methods: This retrospective study enrolled newly diagnosed NPC patients from the Chang Gung Research Database between January 2007 and December 2019. We analyzed the patients’ characteristics and survival outcomes after recurrence. Results: A total of 2599 NPC patients were enrolled. The overall recurrence rate was 20.5%, while 8.1% of patients had long-latent recurrence (>five years). These patients had a higher percentage of initial AJCC (The American Joint Committee on Cancer) stage I/II (60.5%, p = 0.001) and local recurrence (46.5%, p < 0.001). Unresectable rT3 and rT4 were found in 60% of patients when recurrence and 30% of local recurrence occurred in the skull base, which could not be detected by the regular endoscopy. The five-year overall survival rate of long-latent recurrence was 19.7%. Alive patients tended to be asymptomatic but have regular follow-ups with the interval less than six months. Multivariate analysis showed age and initial advanced AJCC stages were independent risk factors of death after recurrence. In contrast, patients with recurrence between two and five years, salvage surgeries, and regional recurrence had favorable survival outcomes. Conclusion: Long-latent NPC recurrence is not rare, and the survival outcome is poor. Regular follow-up for early detection of NPC recurrence is necessary even after five years of disease-free period.

C2orf40 inhibits metastasis and regulates chemo-resistance and radio-resistance of nasopharyngeal carcinoma cells by influencing cell cycle and activating the PI3K/AKT/mTOR signaling pathway

Background

Nasopharyngeal carcinoma (NPC) is a malignant tumor of epithelial origin in head and neck with high incidence rate in Southern China. C2orf40 has been identified as a tumor suppressor gene in many cancers. However, the roles of C2orf40 in nasopharyngeal carcinoma has not been studied.

Methods

In this study, a bioinformatics analysis was performed to identify the differentially expressed genes in NPC. The quantitative methylation levels was detected using pyrosequencing. qRT-PCR, western blotting, immunohistochemistry and immunofluorescence were used to detect the expression level of related RNA and proteins. Cell proliferation was detected using CCK-8 assay, and colony formation capability was detected using colony formation assays. Cell migration and invasion were analyzed using wound-healing and Transwell assays, respectively. The apoptosis level of cells was assessed using TUNEL staining. Endogenous DNA damage and repair were assessed by the comet assay. Cell cycle analyses carried out by flow cytometry. Finally, We used a xenograft nude mouse to verify the roles of C2orf40 in chemoresistance and radioresistance in vivo.

Results

We found that the C2orf40 expression was significantly downregulated in NPC tissues and inversely associated with a poor prognosis. In vivo and in vitro functional experiments confirmed that overexpression of C2orf40 significantly inhibited the migration and invasion of NPC cells, and promoted their sensitivity to radiotherapy and chemotherapy of NPC cells. Mechanically, the expression level of C2orf40 was negatively correlated with the expression levels of CCNE1 and CDK1. Overexpression of C2orf40 induced cell cycle arrest of NPC cells at G/M phase. In addition, C2orf40 can down-regulated the expression levels of homologous recombination-related proteins (BRCA1, BRCA2, RAD51, and CDC25A) and inhibited the activity of the PI3K/AKT/mTOR signaling pathway.

Conclusion

The results clarified the biological functions and mechanisms of C2orf40, as a tumor suppressor gene, in NPC, and provided a potential molecular target for improving the sensitivity of NPC to radiotherapy and chemotherapy.

Inhibition of mTOR by temsirolimus overcomes radio-resistance in nasopharyngeal carcinoma

Radio-resistance is a leading cause of nasopharyngeal carcinoma (NPC) treatment failure and identification of sensitizing therapeutic target is an unmet need to enhance clinical management. Given that the mammalian target of rapamycin (mTOR) signaling confers resistance to cancer therapy, we investigated whether mTOR contributes to radio-resistance in NPC and pharmacological inhibition of mTOR can overcome radio-resistance. We found that mTOR mRNA and protein levels, and phosphorylation of its downstream effector were increased in radio-resistant NPC compared with parental cells. mTOR inhibitor temsirolimus inhibits proliferation and induces apoptosis in a panel of NPC cell lines. Importantly, temsirolimus acts synergistically with radiation and is effective against radio-resistant cells. Using radio-resistant xenograft mouse model, we validated the efficacy of temsirolimus in preventing tumor formation and inhibiting tumor growth. Temsirolimus overcome radio-resistance in NPC via inhibiting mTOR signaling. Our work provides the pre-clinical evidence that the combination of radiation and mTOR inhibitor may be a therapeutic strategy in NPC. Our findings might accelerate the initiation of clinical trials on radio-resistant NPC patients using temsirolimus. This article is protected by copyright. All rights reserved.

miR-26a-5p suppresses nasopharyngeal carcinoma progression by inhibiting PTGS2 expression

Nasopharyngeal carcinoma (NPC) has a low five-year survival rate, and its pathogenesis remains unclear. There is an urgent need to improve our understanding of the genetic regulation of NPC tumorigenesis and development. The role of miR-26a-5p in NPC growth regulation and the expression of its target, PTGS2, was analyzed. Quantitative Real-time PCR assay was used to detect miR-26a-5p and PTGS2 expression in human NPC tissues and cell lines. The RNA pull-down dual-luciferase reporter assay was used to determine the association between miR-26a-5p and PTGS2. The effects of miR-26a-5p and PTGS2 on NPC cell viability, proliferation, migration, and invasion were measured by CCK-8, BrdU, and Transwell assays. miR-26a-5p expression in NPC tissues and cell lines was significantly decreased. The overexpression of miR-26a-5p inhibited the viability, proliferation, migration, and invasion of NPC cells. miR-26a-5p bound to the 3-'untranslated region of PTGS2, thus reducing PTGS2 protein levels. miR-26a-5p inhibited NPC development by reducing the expression of its target PTGS2.

Tumor-derived extracellular vesicles inhibit HGF/c-Met and EGF/EGFR pathways to accelerate the radiosensitivity of nasopharyngeal carcinoma cells via microRNA-142-5p delivery

Radioresistance prevails as one of the largest obstacles in the clinical treatment of nasopharyngeal carcinoma (NPC). Meanwhile, tumor-derived extracellular vesicles (TEVs) possess the ability to manipulate radioresistance in NPC. However, its mechanism remains to be further explored. Therefore, the current study set out to explore the mechanism of microRNA (miR)-142-5p delivered by TEVs in regard to the radiosensitivity of NPC. Firstly, peripheral blood samples were collected from patients with radioresistance and radiosensitivity, followed by RT-qPCR detection of miR-142-5p expression. A dual-luciferase reporter assay was carried out to elucidate the targeting relationship of miR-142-5p with HGF and EGF. In addition, radiotherapy-resistant NPC cell models were established by screening NPC cells with gradient increasing radiation exposure, and co-incubated with EVs isolated from miR-142-5p mimic-transfected NPC cells, followed by overexpression of HGF and EGF. Moreover, cell viability was detected by means of MTS, cell proliferation with a colony formation assay, cell apoptosis with flow cytometry, and expression patterns of related genes with the help of Western blot analysis. NPC xenotransplantation models in nude mice were also established by subcutaneous injection of 5-8FR cells to determine apoptosis, tumorigenicity, and radiosensitivity in nude mice. It was found that miR-142-5p was poorly expressed in peripheral blood from NPC patients with radioresistance. Mechanistic experimentation illustrated that miR-142-5p inversely targeted HGF and EGF to inactivate the HGF/c-Met and EGF/EGFR pathways, respectively. NPC cell apoptosis was observed to be augmented, while their radioresistance and proliferation were restricted by EVs-miR-142-5p or HGF silencing, or EGF silencing. Furthermore, EVs-miR-142-5p inhibited growth and radioresistance and accelerated the apoptosis of radiotherapy-resistant NPC cells in nude mice by inhibiting the HGF/c-Met and EGF/EGFR pathways. Collectively, our findings indicated that TEVs might inhibit the HGF/c-Met and EGF/EGFR pathways by delivering miR-142-5p into radiotherapy-resistant NPC cells to enhance radiosensitivity in NPC.

CRISPR/Cas9 genome-wide screening identifies LUC7L2 that promotes radioresistance via autophagy in nasopharyngeal carcinoma cells

Radioresistance emerges as the major obstacle to nasopharyngeal carcinoma (NPC) treatment, further understanding of underlying mechanisms is necessary to overcome the radioresistance and improve the therapeutic effect. In this study, we first identified a candidate radioresistant-related gene LUC7L2 via CRISPR/Cas9 high-throughput screening and quantitative proteomic approach. Overexpression of LUC7L2 in NPC cells promoted cell viability following exposure to ionizing radiation (IR), while knockdown of LUC7L2 significantly slowed down the DNA replication and impaired cell survival, sensitized NPC-radioresistant cells to IR. Using immunoprecipitation assay, we found SQSTM1, an autophagy receptor, was a potential binding partner of LUC7L2. Down-regulation of LUC7L2 in NPC-radioresistant cells led to reduction of SQSTM1 expression and enhancement of autophagy level. Furthermore, LUC7L2 knockdown in combination with autophagy inhibitor, chloroquine (CQ), resulted in more NPC-radioresistant cell death. Besides, LUC7L2 was obviously distributed in NPC tissues, and high LUC7L2 expression correlated with shorter survival in NPC patients. Our data suggest that LUC7L2 plays a huge part in regulating radioresistance of NPC cells, and serves as a promising therapeutic target in re-sensitizing NPC to radiotherapy.

The Role of Genetic Pathways in the Development of Chemoradiation Resistance in Nasopharyngeal Carcinoma (NPC) Patients

Management of nasopharyngeal carcinoma (NPC) remains elusive despite new developments and advancement that has been made in the current management approaches. A patient’s survival and prognosis remain dismal especially for a late-stage disease. This is highly attribute to the chemoradiation resistance. Arrays of genes and molecular mechanisms underlie the development of chemoradiation resistance in NPC. Imperatively, unravelling the true pathogenesis of chemoradiation resistance is crucial as these significant proteins and genes can be modulated to produce an effective therapeutic target. It is pivotal to identify the chemoradiation resistance at the very beginning in order to combat the chemoradiation resistance efficiently. Intense research in the genetic ecosphere is critical, as the discovery and development of novel therapeutic targets can be used for screening, diagnosis, and treating the chemoradiation resistance aggressively. This will escalate the management trajectory of NPC patients. This article highlights the significance of genetic and molecular factors that play critical roles in the chemoradiation resistance and how these factors may be modified for next-generation targeted therapy products.

TRAIL sensitivity of nasopharyngeal cancer cells involves redox dependent upregulation of TMTC2 and its interaction with membrane caspase-3

AIMS

Preferential expression of receptors for TNF-family related apoptosis inducing ligand (TRAIL), DR4 and DR5 makes TRAIL an attractive anti-cancer therapeutic. However, the efficacy of targeting death receptors has not been extensively studied in nasopharyngeal cancer (NPC). Here we investigated TRAIL sensitivity and its underlying mechanism in NPC cell lines, and assessed the potential of TRAIL as a therapeutic option against NPC.

RESULTS

Using two established NPC cell lines, we report the expression of DR4 and DR5, which respond to TRAIL ligation by triggering efficient Type II apoptosis. Mechanistically, early activation of caspase-3 and its membrane recruitment is identified in NPC cell lines, which is associated with, hitherto unreported, interaction with transmembrane and tetratricopeptide repeat containing 2 (TMTC2) in the lipid raft domains. TMTC2 expression is induced upon exposure to TRAIL and involves intracellular increase in peroxynitrite (ONOO-) production. While ONOO- increase is downstream of caspase-8 activation, it is involved in the upregulation of TMTC2, gene knockdown of which abrogated TRAIL-induced apoptotic execution. Bioinformatics analyses also provide evidence for a strong correlation between TMTC2 and DR4 or caspase-3 as well as a significantly better disease-free survival in patients with high TMTC2 expression.

INNOVATION AND CONCLUSION

Collectively, redox-dependent execution of NPC cells upon ligation of TRAIL receptors reintroduces the possible therapeutic use of TRAIL in NPC as well as underscores the potential of using TMTC2 as a biomarker of TRAIL sensitivity.

Clinical therapeutic effects of acupuncture in treating patients with dysphagia after radiotherapy in nasopharyngeal carcinoma: A protocol for systematic review and meta-analysis

BACKGROUND

Dysphagia is a commonly occurring condition in nasopharyngeal carcinoma (NPC) patients after radiotherapy. There has been an increasing number of studies focused on assessing the use of acupuncture to manage dysphagia. Moreover, the quality of the research has gradually increased. The present research will be conducted to systematically evaluate the efficiency and safety of using acupuncture to treat cases of dysphagia after radiation therapy in NPC patients.

METHODS

Literature search will include all potential randomized controlled trials using MEDLINE, Cochrane Library, Web of Science, EMBASE, Chinese National Knowledge Infrastructure, Chinese BioMedical Literature, and WanFang database from their inception to May, 2021 without language or publication status restrictions, to evaluate the efficiency and safety of using acupuncture to treat dysphagia cases following radiation therapy in NPC patients. A couple of independent authors will select related literature, extract data from studies, and estimate this risk in the bias of the selected study articles. In the instance of contrasting opinions, the outcome is mediated through discussion with a different independent author. The data synthesis and statistical analysis will be completed with the RevMan software (version 5.3).

RESULTS

This study will evaluate the efficiency and safety of using acupuncture to treat dysphagia cases after radiation therapy in NPC patients.

CONCLUSION

This study will determine the suitability of acupuncture as an effective and safe intervention for dysphagia in NPC patients after radiotherapy.

ETHICS AND DISSEMINATION

The present study does not need ethical approval.

REGISTRATION NUMBER

May 19, 2021.osf.io/f2cvt. (https://osf.io/f2cvt/).

The role of Exosomes in the Pathogenesis of Nasopharyngeal Carcinoma and the involved Clinical Application

Exosomes are nanoscale membrane vesicles, which carry biologically active substances of their cell of origin and play an important role in signal transduction and intercellular communication. At present, exosomes have been identified as a promising non-invasive liquid biopsy biomarker in the tissues and circulating blood of nasopharyngeal carcinoma (NPC) and found to participate in regulating pathophysiological process of the tumor. We here review recent insights gained into the molecular mechanisms of exosome-induced cell growth, angiogenesis, metastasis, immunosuppression, radiation resistance and chemotherapy resistance in the development and progression of NPC, as well as the clinical application of exosomes as diagnostic biomarkers and therapeutic agents. We also discuss the limitations and challenges in exosome application. We hope this review may provide some references for the use of exosomes in clinical intervention.

EBV-LMP1 promotes radioresistance by inducing protective autophagy through BNIP3 in nasopharyngeal carcinoma

Studies have indicated that dysfunction of autophagy is involved in the initiation and progression of multiple tumors and their chemoradiotherapy. Epstein–Barr virus (EBV) is a lymphotropic human gamma herpes virus that has been implicated in the pathogenesis of nasopharyngeal carcinoma (NPC). EBV encoded latent membrane protein1 (LMP1) exhibits the properties of a classical oncoprotein. In previous studies, we experimentally demonstrated that LMP1 could increase the radioresistance of NPC. However, how LMP1 contributes to the radioresistance in NPC is still not clear. In the present study, we found that LMP1 could enhance autophagy by upregulating the expression of BCL2/adenovirus E1B 19 kDa protein-interacting protein 3 (BNIP3). Knockdown of BNIP3 could increase the apoptosis and decrease the radioresistance mediated by protective autophagy in LMP1-positive NPC cells. The data showed that increased BNIP3 expression is mediated by LMP1 through the ERK/HIF1α signaling axis, and LMP1 promotes the binding of BNIP3 to Beclin1 and competitively reduces the binding of Bcl-2 to Beclin1, thus upregulating autophagy. Furthermore, knockdown of BNIP3 can reduce the radioresistance promoted by protective autophagy in vivo. These data clearly indicated that, through BNIP3, LMP1 induced autophagy, which has a crucial role in the protection of LMP1-positive NPC cells against irradiation. It provides a new basis and potential target for elucidating LMP1-mediated radioresistance.

The molecular march of primary and recurrent nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) results from the aberrant and uncontrolled growth of the nasopharyngeal epithelium. It is highly associated with the Epstein-Barr virus, especially in regions where it is endemic. In the last decade, significant advances in genetic sequencing techniques have allowed the discovery of many new abnormal molecular processes that undoubtedly contribute to the establishment, growth and spread of this deadly disease. In this review, we consider NPC as EBV induced. We summarise the recent discoveries and how they add to our understanding of the pathophysiology of NPC in the context of genomics first in primary and then in recurrent disease. Overall, we find key early events lead to p16 inactivation and cyclin D1 expression, allowing latent viral infection. Host and viral factors work together to affect a variety of molecular pathways, the most fundamental being activation of NF-κB. Nonetheless, much still yearns to be discovered, especially in recurrent NPC.

Label-Free Follow-Up Surveying of Post-Treatment Efficacy and Recurrence in Nasopharyngeal Carcinoma Patients with Fiberoptic Raman Endoscopy

Recurrent nasopharyngeal carcinoma (NPC) is the main cause of poor prognosis for NPC patients after chemo- and radiotherapies. Subsequent long-term follow-ups of post-treatment patients are crucial for the early discovery of tumor recurrence with timely intervention. Current clinical imaging methods based on tissue morphology encounter difficulties in differentiating recurrent tumors from post-treatment inflammation and fibrosis. In this work, we apply a unique fiberoptic Raman endoscopy technique to address the challenges for label-free follow-up surveying of post-treatment NPC patients and accurate detection of tumor recurrence. Significant Raman spectral differences can be observed among normal, NPC, and nonrecurring post-treatment patients. Raman endoscopy provides diagnostic accuracy of 100% for detecting recurrent NPC from early post-treatment inflammation and diagnostic accuracy of 98.21% for separating recurrent NPC from long-term post-treatment fibrosis. Further quantitative Raman modeling on in vivo nasopharyngeal tissue Raman data acquired unveils the changes of major tissue biochemicals (e.g., triolein, elastin, keratin, fibrillar collagen, and type IV collagen) associated with primary NPC and post-treatment recurrent NPC tissue compared to normal nasopharyngeal tissue. This work demonstrates that fiberoptic Raman endoscopy can be a clinically powerful diagnostic tool for rapid, label-free post-treatment surveying and recurrent tumor detection in NPC patients at the molecular level.

Exploiting DNA repair pathways for tumor sensitization, mitigation of resistance, and normal tissue protection in radiotherapy

More than half of cancer patients are treated with radiotherapy, which kills tumor cells by directly and indirectly inducing DNA damage, including cytotoxic DNA double-strand breaks (DSBs). Tumor cells respond to these threats by activating a complex signaling network termed the DNA damage response (DDR). The DDR arrests the cell cycle, upregulates DNA repair, and triggers apoptosis when damage is excessive. The DDR signaling and DNA repair pathways are fertile terrain for therapeutic intervention. This review highlights strategies to improve therapeutic gain by targeting DDR and DNA repair pathways to radiosensitize tumor cells, overcome intrinsic and acquired tumor radioresistance, and protect normal tissue. Many biological and environmental factors determine tumor and normal cell responses to ionizing radiation and genotoxic chemotherapeutics. These include cell type and cell cycle phase distribution; tissue/tumor microenvironment and oxygen levels; DNA damage load and quality; DNA repair capacity; and susceptibility to apoptosis or other active or passive cell death pathways. We provide an overview of radiobiological parameters associated with X-ray, proton, and carbon ion radiotherapy; DNA repair and DNA damage signaling pathways; and other factors that regulate tumor and normal cell responses to radiation. We then focus on recent studies exploiting DSB repair pathways to enhance radiotherapy therapeutic gain.

Systemic Inflammation Response Index Is a Predictor of Poor Survival in Locally Advanced Nasopharyngeal Carcinoma: A Propensity Score Matching Study

Introduction

Nasopharyngeal carcinoma (NPC) is a common malignancy in China and known prognostic factors are limited. In this study, neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), systemic immune inflammation index (SII), and systemic inflammation response index (SIRI) were evaluated as prognostic factors in locally advanced NPC patients.

Materials and Methods

NPC patients who received curative radiation or chemoradiation between January 2012 and December 2015 at the Second Xiangya Hospital were retrospectively reviewed, and a total of 516 patients were shortlisted. After propensity score matching (PSM), 417 patients were eventually enrolled. Laboratory and clinical data were collected from the patients' records. Receiver operating characteristic curve analysis was used to determine the optimal cut-off value. Survival curves were analyzed using the Kaplan-Meier method. The Cox proportional hazard model was used to identify prognostic variables.

Results

After PSM, all basic characteristics between patients in the high SIRI group and low SIRI group were balanced except for sex (p=0.001) and clinical stage (p=0.036). Univariate analysis showed that NLR (p=0.001), PLR (p=0.008), SII (p=0.001), and SIRI (p<0.001) were prognostic factors for progression-free survival (PFS) and overall survival (OS). However, further multivariate Cox regression analysis showed that only SIRI was an independent predictor of PFS and OS (hazard ratio (HR):2.83; 95% confidence interval (CI): 1.561-5.131; p=0.001, HR: 5.19; 95% CI: 2.588-10.406; p<0.001), respectively.

Conclusion

Our findings indicate that SIRI might be a promising predictive indicator of locally advanced NPC patients.

Suppressing UVRAG Induces Radiosensitivity by Triggering Lysosomal Membrane Permeabilization in Hypopharyngeal Squamous Cell Carcinoma

Introduction

Radiotherapy is one of the most important methods in the treatment of patients with hypopharyngeal squamous cell carcinoma (HSCC). However, radioresistance will be developed after repeated irradiation. Among many key factors contributing to radioresistance, enhanced autophagy is recognized as one of the most important. The ultraviolent irradiation resistance-associated gene (UVRAG) is reported to be a crucial gene involved in the process of autophagy. Here, we test whether UVRAG has effect on the radioresistance of HSCC.

Methods

HSCC cell line Fadu cells were treated with irradiation to test levels of autophagy. Tumor tissues from primary and recurrent HSCC patients were tested by immunohistochemistry. Then, we knocked down UVRAG to test its role in cell growth and the malignant behaviors. Response of cells to treatment was examined using LDH release assay, immunofluorescence, Western blot analysis and colony formation.

Results

We found that irradiation induced autophagy in Fadu cells. Immunohistochemistry of primary and irradiated HSCC tumor tissues showed that UVRAG was upregulated after irradiation treatment. Inhibiting UVRAG with siRNA interfered cell growth, cell cycle, malignant behaviors and autophagic flux in Fadu cells. Knocking down UVRAG increased DNA damage and cell death induced by irradiation. Finally, we found that inhibiting UVRAG induced lysosomal membrane permeabilization, which contributed to radiosensitization of Fadu cells.

Conclusion

Our findings supported the oncogenic properties of UVRAG in HSCC and inhibiting UVRAG increased radiosensitivity in HSCC by triggering lysosomal membrane permeabilization. Therefore, UVRAG might be a promising target in the treatment of HSCC.

Understanding the roles of stress granule during chemotherapy for patients with malignant tumors

The assembly of stress granules (SGs) is a conserved mechanism to regulate protein synthesis under cell stress, where the translation of global protein is silenced and selective protein synthesis for survival maintains. SG formation confers survival advantages and chemotherapeutic resistance to malignant cells. Targeting SG assembly may represent a potential treatment strategy to overcome the primary and acquired chemotherapeutic resistance and enhance curative effect. We conduct a comprehensive review of the published literatures focusing on the drugs that potentially induce SGs and the related mechanism, retrospect the relationship between SGs and drug resistance related proteins, illuminate the regulated pathways and potential targets for SG assembly, and discuss future directions of overcoming the resistance to chemotherapy.