Membrane vesicles derived from Enterococcus faecalis promote the co-transfer of important antibiotic resistance genes located on both plasmids and chromosomes.

BACKGROUND: Bacterial membrane vesicles (BMVs) are novel vehicles of antibiotic resistance gene (ARG) transfer in Gram-negative bacteria, but their role in the spread of ARGs in Gram-positive bacteria has not been defined. The purpose of this study was to evaluate the role of MVs in the transmission of antimicrobial resistance in Gram-positive bacteria. METHODS: A linezolid-resistant Enterococcus faecalis CQ20 of swine origin was selected as the donor strain. Linezolid-susceptible E. faecalis SC032 of human origin, Enterococcus faecium BM4105 and Escherichia coli were selected as recipient strains. The presence of plasmids (pCQ20-1 and pCQ20-2) and an optrA-carrying transposon Tn6674 in CQ20, MVs and vesiculants was verified by WGS or PCR. MVs were isolated with density gradient centrifugation, and MV-mediated transformation was performed to assess the horizontal transferability of MVs. The MICs for CQ20 and its vesiculants were determined by the broth microdilution method. RESULTS: CQ20-derived MVs (CQ20-MV) were isolated, and PCR identified the presence of two plasmids and the optrA gene in the CQ20-MVs. MV-mediated transformation to E. faecalis SC032 and E. faecium BM4105 was successfully performed, and the WGS data also showed that both plasmids pCQ20-1 and pCQ20-2 and optrA-carrying transposon Tn6674 were transferred to E. faecalis SC032 and E. faecium BM4105, but failed for E. coli. Additionally, vesiculants that had acquired ARGs still had the ability to spread these genes via MVs. CONCLUSIONS: To our knowledge, this is the first report of MV-mediated co-transfer of ARG-carrying plasmids and transposons in the Gram-positive bacterium E. faecium.

Benefit of consolidative radiation in patients with extranodal limited-stage diffuse large B-cell lymphoma: a multicenter retrospective study in China.

Approximately 40% of limited-stage (stage I and II) diffuse large B-cell lymphoma (LS-DLBCL) presents with extranodal disease. Extranodal LS-DLBCL may have significant biological differences and associated with worse outcomes than nodal disease. Although rituximab based chemoimmunotherapy is standard of first-line treatment, the role of consolidative radiotherapy (RT) in this particular subgroup is controversial. In this multicenter retrospective study, we evaluated the survival benefit of consolidative RT in patients diagnosed with extranodal LS-DLBCL and received rituximab-based chemoimmunotherapy with or without consolidative RT. A total of 328 patients were included, 129 patients (39.3%) received chemoimmunotherapy and consolidative RT, and 199 patients (60.7%) received chemoimmunotherapy alone. With a median follow-up of 5.1 years (range, 0.3-14.8 years), 5-year progression-free survival (PFS) and overall survival (OS) for all patients were 75.4% and 83.9%, respectively. In multivariate analyses, the addition of consolidative RT was associated with superior OS (P = 0.004) and PFS (P = 0.005). High stage-modified International Prognosis Index (SM-IPI) risk predicted worse OS (P = 0.001) and PFS (P = 0.005). Also, propensity score-matched analyses showed RT improved both OS (hazard ratio [HR] 0.228, 95% confidence index [CI] 0.111-0.467, P < 0.001) and PFS (HR 0.308, 95% CI 0.167-0.566, P < 0.001). Among patients who achieved CR, 49 patients (16.6%) developed disease relapse, of which 30.6% relapsed at local sites. Consolidative RT significantly reduced relapse risk (P = 0.002). Our results demonstrated that consolidative RT significantly improved outcomes in patients with extranodal LS-DLBCL in the rituximab era.

Human glioma cells-conditioned medium promotes proliferation and migration of human bone marrow mesenchymal stromal cells in vitro.

PURPOSE: To investigate changes in cell proliferation and migration of human bone marrow-derived mesenchymal stromal cells (hMSCs) in glioma environment, in order to assess the tumorigenic risk of hMSCs in the clinical application to treat human gliomas. METHODS: hMSCs were obtained from normal adult persons and identified by their morphological characteristics and test of their stemness. The U251 glioma cell-conditioned medium (U251-CM) was obtained to simulate the human glioma environment in vitro. hMSCs were cultured in the U251-CM or the control medium in the same conditionzs and changes in cell proliferation and migration were detected by MTT assay and wound healing assay. RESULTS: The results of MTT assay showed that, compared with the control group, the proliferation of hMSCs cultured in U251-CM increased significantly, and the results of wound healing assay showed that the migration of hMSCs cultured in U251-CM also increased significantly. CONCLUSIONS: Human glioma cell-conditioned medium may promote the proliferation and migration of hMSCs, and we are concerned about the tumorigenic risk of hMSCs in glioma environment before their clinical application.

Genomic features reveal potential benefit of adding anti-PD-1 immunotherapy to treat non-upper aerodigestive tract natural killer/T-cell lymphoma.

Natural killer/T-cell lymphoma (NKTCL) is a highly heterogeneous disease with a poor prognosis. However, the genomic characteristics and proper treatment strategies for non-upper aerodigestive tract NKTCL (NUAT-NKTCL), a rare subtype of NKTCL, remain largely unexplored. In this study, 1589 patients newly diagnosed with NKTCL at 14 hospitals were assessed, 196 (12.3%) of whom had NUAT-NKTCL with adverse clinical characteristics and an inferior prognosis. By using whole-genome sequencing (WGS) and whole-exome sequencing (WES) data, we found strikingly different mutation profiles between upper aerodigestive tract (UAT)- and NUAT-NKTCL patients, with the latter group exhibiting significantly higher genomic instability. In the NUAT-NKTCL cohort, 128 patients received frontline P-GEMOX chemotherapy, 37 of whom also received anti-PD-1 immunotherapy. The application of anti-PD-1 significantly improved progression-free survival (3-year PFS rate 53.9% versus 17.0%, P = 0.009) and overall survival (3-year OS rate 63.7% versus 29.2%, P = 0.01) in the matched NUAT-NKTCL cohort. WES revealed frequent mutations involving immune regulation and genomic instability in immunochemotherapy responders. Our study showed distinct clinical characteristics and mutational profiles in NUAT-NKTCL compared with UAT patients and suggested adding anti-PD-1 immunotherapy in front-line treatment of NUAT-NKTCL. Further studies are needed to validate the efficacy and related biomarkers for immunochemotherapy proposed in this study.

Saracatinib (AZD0530) is a potent modulator of ABCB1-mediated multidrug resistance in vitro and in vivo.

Saracatinib, a highly selective, dual Src/Abl kinase inhibitor, is currently in a Phase II clinical trial for the treatment of ovarian cancer. In our study, we investigated the effect of saracatinib on the reversal of multidrug resistance (MDR) induced by ATP-binding cassette (ABC) transporters in vitro and in vivo. Our results showed that saracatinib significantly enhanced the cytotoxicity of ABCB1 substrate drugs in ABCB1 overexpressing HeLa/v200, MCF-7/adr and HEK293/ABCB1 cells, an effect that was stronger than that of gefitinib, whereas it had no effect on the cytotoxicity of the substrates in ABCC1 overexpressing HL-60/adr cells and its parental sensitive cells. Additionally, saracatinib significantly increased the doxorubicin (Dox) and Rho 123 accumulation in HeLa/v200 and MCF-7/adr cells, whereas it had no effect on HeLa and MCF-7 cells. Furthermore, saracatinib stimulated the ATPase activity and inhibited photolabeling of ABCB1 with [(125)I]-iodoarylazidoprazosin in a concentration-dependent manner. In addition, the homology modeling predicted the binding conformation of saracatinib within the large hydrophobic drug-binding cavity of human ABCB1. However, neither the expression level of ABCB1 nor the phosphorylation level of Akt was altered at the reversal concentrations of saracatinib. Importantly, saracatinib significantly enhanced the effect of paclitaxel against ABCB1-overexpressing HeLa/v200 cancer cell xenografts in nude mice. In conclusion, saracatinib reverses ABCB1-mediated MDR in vitro and in vivo by directly inhibiting ABCB1 transport function, without altering ABCB1 expression or AKT phosphorylation. These findings may be helpful to attenuate the effect of MDR by combining saracatinib with other chemotherapeutic drugs in the clinic.

The clinical and genomic distinctions of Class1/2/3 BRAF-mutant colorectal cancer and differential prognoses.

BRAF mutations are the oncogenic drivers in colorectal cancer and V600 mutations (Class1), which lead to RAS-independent active monomers, are the most common mutation types. BRAF non-V600 mutants can be further classified as RAS-independent active dimers (Class2) and RAS-dependent impaired kinase (Class3). We retrospectively reviewed the mutational profiles of 328 treatment-naïve colorectal tumors with BRAF mutations detected using capture-based hybrid next-generation sequencing targeting 400 + cancer-related genes. The clinical and genetic distinctions of patients harboring Class1/2/3 BRAF mutations were investigated, which revealed that tumors with Class1 BRAF mutations showed more unique genomic profiles than those with Class2/3 mutations. Also, by using an external dataset from cBioPortal, we demonstrated that patients with Class3 BRAF mutations had the best survival outcomes compared to the other two subgroups. These findings promoted the development of anti-BRAF strategies by distinguishing BRAF mutant subgroups.

Neratinib reverses ATP-binding cassette B1-mediated chemotherapeutic drug resistance in vitro, in vivo, and ex vivo.

Neratinib, an irreversible inhibitor of epidermal growth factor receptor and human epidermal receptor 2, is in phase III clinical trials for patients with human epidermal receptor 2-positive, locally advanced or metastatic breast cancer. The objective of this study was to explore the ability of neratinib to reverse tumor multidrug resistance attributable to overexpression of ATP-binding cassette (ABC) transporters. Our results showed that neratinib remarkably enhanced the sensitivity of ABCB1-overexpressing cells to ABCB1 substrates. It is noteworthy that neratinib augmented the effect of chemotherapeutic agents in inhibiting the growth of ABCB1-overexpressing primary leukemia blasts and KBv200 cell xenografts in nude mice. Furthermore, neratinib increased doxorubicin accumulation in ABCB1-overexpressing cell lines and Rhodamine 123 accumulation in ABCB1-overexpressing cell lines and primary leukemia blasts. Neratinib stimulated the ATPase activity of ABCB1 at low concentrations but inhibited it at high concentrations. Likewise, neratinib inhibited the photolabeling of ABCB1 with [(125)I]iodoarylazidoprazosin in a concentration-dependent manner (IC(50) = 0.24 µM). Neither the expression of ABCB1 at the mRNA and protein levels nor the phosphorylation of Akt was affected by neratinib at reversal concentrations. Docking simulation results were consistent with the binding conformation of neratinib within the large cavity of the transmembrane region of ABCB1, which provides computational support for the cross-reactivity of tyrosine kinase inhibitors with human ABCB1. In conclusion, neratinib can reverse ABCB1-mediated multidrug resistance in vitro, ex vivo, and in vivo by inhibiting its transport function.

Axitinib targeted cancer stemlike cells to enhance efficacy of chemotherapeutic drugs via inhibiting the drug transport function of ABCG2.

Stemlike cells have been isolated by their ability to efflux Hoechst 33342 dye and are called the side population (SP). We evaluated the effect of axitinib on targeting cancer stemlike cells and enhancing the efficacy of chemotherapeutical agents. We found that axitinib enhanced the cytotoxicity of topotecan and mitoxantrone in SP cells sorted from human lung cancer A549 cells and increased cell apoptosis induced by chemotherapeutical agents. Moreover, axitinib particularly inhibited the function of adenosine triphosphate (ATP)-binding cassette subfamily G member 2 (ABCG2) and reversed ABCG2-mediated multidrug resistance (MDR) in vitro. However, no significant reversal effect was observed in ABCB1-, ABCC1- or lung resistance-related protein (LRP)-mediated MDR. Furthermore, in both sensitive and MDR cancer cells axitinib neither altered the expression of ABCG2 at the mRNA or protein levels nor blocked the phosphorylation of AKT and extracellular signal-regulated kinase (ERK)1/2. In nude mice bearing ABCG2-overexpressing S1-M1-80 xenografts, axitinib significantly enhanced the antitumor activity of topotecan without causing additional toxicity. Taken together, these data suggest that axitinib particularly targets cancer stemlike cells and reverses ABCG2-mediated drug resistance by inhibiting the transporter activity of ABCG2.

Enhancing chemosensitivity in ABCB1- and ABCG2-overexpressing cells and cancer stem-like cells by an Aurora kinase inhibitor CCT129202.

Imidazopyridine CCT129202 is an inhibitor of Aurora kinase activity and displays a favorable antineoplastic effect in preclinical studies. Here, we investigated the enhanced effect of CCT129202 on the cytotoxicity of chemotherapeutic drugs in multidrug resistant (MDR) cells with overexpression of ATP-binding cassette (ABC) transporters and cancer stem-like cells. CCT129202 of more than 90% cell survival concentration significantly enhanced the cytotoxicity of substrate drugs and increased the intracellular accumulations of doxorubicin and rhodamine 123 in ABCB1 and ABCG2 overexpressing cells, while no effect was found on parental sensitive cells. Interestingly, CCT129202 also potentiated the sensitivity of cancer stem-like cells to doxorubicin. Importantly, CCT129202 increased the inhibitory effect of vincristine and paclitaxel on ABCB1 overexpressing KBv200 cell xenografts in nude mice and human esophageal cancer tissue overexpressing ABCB1 ex vivo, respectively. Furthermore, the ATPase activity of ABCB1 was inhibited by CCT129202. Homology modeling predicted the binding conformation of CCT129202 within the large hydrophobic cavity of ABCB1. On the other hand, CCT129202 neither apparently altered the expression levels of ABCB1 and ABCG2 nor inhibited the activity of Aurora kinases in MDR cells under the concentration of reversal MDR. In conclusion, CCT129202 significantly reversed ABCB1- and ABCG2-mediated MDR in vitro, in vivo and ex vivo by inhibiting the function of their transporters and enhanced the eradication of cancer stem-like cells by chemotherapeutic agents. CCT129202 may be a candidate as MDR reversal agent for antineoplastic combination therapy and merits further clinical investigation.

Non-Hodgkin's lymphoma involving the ileocecal region: a single-institution analysis of 46 cases in a Chinese population.

BACKGROUND AND GOALS: Non-Hodgkin's lymphoma (NHL) involving the ileocecal region is a rare occurrence. Optimal management and treatment outcomes of ileocecal NHL have not been well defined. STUDY: In this study, clinical characteristics, treatment outcomes, and prognostic factors of 46 Chinese patients with ileocecal NHL were retrospectively analyzed. RESULTS: Among 46 patients, the median age of these patients was 46 years and 84.8% of them were male. Twenty-four cases (52.2%) had early-stage disease (stage I/II1/II2) and 35 (76.1%) cases were of B-cell origin. Higher incidence of fever (P=0.001) and intestinal perforation (P=0.038) at onset was observed in T-cell lymphomas. Surgical emergencies occurred in 13 patients, including 8 patients who were receiving chemotherapy. Patients with T-cell advanced ileocecal NHL (stage IIE/IV) suffered more surgical emergencies during chemotherapy than others (P=0.005). The 5-year overall survival and progression-free survival rates for these 46 patients were 64.2% and 49.3%, respectively. Early-stage cases undergoing radical resection before chemotherapy had a prolonged 5-year progression-free survival rate (P=0.01). In multivariate analysis, both advanced stage and T-cell phenotype were identified as independent prognostic factors for poor survival. CONCLUSIONS: Radical resection before chemotherapy should be considered in early-stage ileocecal NHL to achieve a better survival. Palliative resection of the primary lesion before chemotherapy may be necessary in T-cell advanced cases to avoid surgical emergencies during chemotherapy. Owing to the small sample number in this study, a prospective analysis with larger sample number is highly necessary.

Cyclosporine, prednisone, and high-dose immunoglobulin treatment of angioimmunoblastic T-cell lymphoma refractory to prior CHOP or CHOP-like regimen.

Angioimmunoblastic T-cell lymphoma (AITL) is a rare, distinct subtype of peripheral T-cell lymphoma, possessing an aggressive course and poor prognosis with no standard therapy. Twelve patients who have failed at least two initial CHOP or CHOP-like regimens were enrolled in this study and treated with individualized cyclosporine (CsA), prednisone (PDN), and monthly, high-dose intravenous immunoglobulin (HDIVIG). The dose of CsA was adjusted individually based on the blood trough concentration of CsA and renal function. All patients were examined for response, toxicity and survival. The most significant toxicities (≥ grade 2) were infection (16.7%), renal insufficiency (8.3%), hypertension (8.3%), diabetes (8.3%) and insomnia (16.7%). Discontinuation of treatment occurred in one patient (8.3%) due to grade 3 renal toxicity and subsequent grade 4 pulmonary infection. Treatment-related death was not observed. The overall response rate was 75.0% (complete response, 33.3%; partial response, 41.7%). With a median follow-up of 25.5 months, the median duration of response was 20 months (range, 12 to 49 months) and the median progression-free survival (PFS) was 25.5 months (range, 10 to 56 months). The 2-year PFS rate was 81.5%. Our findings indicate the combination of CsA, PDN and HDIVIG is an effective salvage regimen for refractory or relapsed AITL with predictable and manageable toxicity.

Corrigendum to "Epidemiological Trends of Head and Neck Cancer: A Population-Based Study".

[This corrects the article DOI: 10.1155/2021/1738932.].

Epidemiological Trends of Head and Neck Cancer: A Population-Based Study.

BACKGROUND: Over the past decades, lots of advance have occurred in the prevention, diagnosis, and treatment of head and neck cancer (HNC). However, the contemporaneous incidence and survival trends, on the basis of population-based registry, have not been reported. METHODS: The HNC cancer cases were accessed from the Surveillance, Epidemiology, and End Results (SEER) database. The incidence trend was analyzed by joinpoint analysis, with the survival trend being analyzed by period analysis of relative survival rate (RSR) and Kaplan-Meier analyses. Cox regression analysis was performed to identify the prognostic factors for overall survival. RESULTS: The general incidence trend of HNC increases slightly, with an average annual percentage change of 0.6%, along with five fluctuating segments. The improvement of net survival over the past decades was showed by increasing 60-month RSR, from 54.1% to 56.0% to 60.9% to 66.8%, which was further confirmed by Kaplan-Meier analyses. Moreover, disparities in incidence and survival patterns can be observed in different subgroups. CONCLUSION: A fluctuating incidence pattern and an ever-improving survival were observed in HNC over time.

The regulation of cancer cell migration by lung cancer cell-derived exosomes through TGF-ß and IL-10.

Tumorigenesis has been considered to be as a result of abnormal cell-cell communication. It has been proposed that exosomes act as communicators between tumors and their microenvironment and have been demonstrated to be involved in tumorigenesis and subsequent metastasis. However, the mechanisms underlying the role of exosomes in these processes remains elusive. The present study sought to determine the underlying mechanisms. Using two lung cancer cell lines, it was demonstrated that exosomes derived from metastatic small cell lung cancer cells (NCI-H1688) have greater effects on cancer cell migration, compared with exosomes derived from primary non-small cell lung cancer cells (NCI-H2228). Further characterization of the contents of the exosomes demonstrated that there were increased levels of TGF-ß and IL-10 in exosomes from NCI-H1688 cells compared with exosomes derived from NCI-H2228 cells, in particular under hypoxia. Blockade of TGF-ß and IL-10 with antibodies confirmed that these cytokines were essential for the regulation of cancer cell migration. Taken together, the results of the present study indicated that exosomes derived from cancer cells regulated the cellular migration of tumor cells through TGF-ß and IL-10, which may provide a novel approach for developing therapeutic methods against cancer.

Structural and functional characterization of neuromedin S in the teleost fish, zebrafish (Danio rerio).

Neuromedin S (NMS) has been demonstrated to have important roles in many vertebrate physiological processes. However, the function of NMS in teleost fishes remains unclear. We explored the physiological roles of the NMS gene in the zebrafish model. An NMS cDNA was cloned from zebrafish brain tissue, and the full-length cDNA sequence was 521 bp in length and encoded a precursor of 110 amino acid residues. Interestingly, fish prepro-NMS is predicted to generate a short 34-residue peptide, designated as NMS-related peptide (NMSRP). Zebrafish prepro-NMS does not contain the NMS peptide which is found in the NMS precursors of mammals, and just retains the MNSRP peptide. A multiple-species sequence alignment showed that NMSRPs are conserved among the other sampled vertebrates. Zebrafish NMS mRNA was detected by RT-PCR revealing a tissue-specific distribution with high levels of expression in the brain, spleen, ovary, pituitary, and muscle. Furthermore, the locations of NMS-expressing cells in the zebrafish brain were detected by in situ hybridization in the parvocellular preoptic nucleus (PPa), the ventral zone of the periventricular hypothalamus (Hv), and lateral hypothalamic nucleus (LH). The levels of NMS mRNA in the hypothalamus were significantly increased after three days of food deprivation. Administration of zebrafish NMSRP by intraperitoneal injection significantly promoted the expression of neuropeptide Y (NPY) and orexin, suggesting an orexigenic role for NMSRP in zebrafish. The present study offers a new understanding of the NMS gene in vertebrates and increases our knowledge of the neuroendocrine regulation of feeding.

Controversies regarding T status and N status for non-small cell lung cancer.

According to the newest version of NCCN Clinical Practice Guidelines for Non-Small Cell Lung Cancer (NSCLC), increasing attentions are paid to the role of nodal status and other high-risk factors, including vascular invasion, wedge resection, tumors > 4 cm, visceral pleural involvement, and incomplete lymph node sampling in the individual clinical treatment. Precise definitions of T status and N status, closely associated with prognosis and treatment, are worth expanding further. However, complexity arises because no unity definition exists regarding individual T and N descriptors. In an attempt to explore the potential prognostic values of the T status and N status, we systematically review relevant literature and found that there still remained some disputes about the definitions and prognosis. The adjacent lobe invasion regarded as T2 or T3 has not been reached consensus yet so far. Lymph node spread patterns are associated with the treatment strategies of NSCLC. This review mainly focus on the role of T status and N status and tried to seek appropriate and individual treatment strategies in NSCLC.

An updated meta-analysis of fatal adverse events caused by bevacizumab therapy in cancer patients.

BACKGROUND: The risk of fatal adverse events (FAEs) due to bevacizumab-based chemotherapy has not been well described; we carried out an updated meta-analysis regarding this issue. METHODS: An electronic search of Medline, Embase and The Cochrane Central Register of Controlled Trials was conducted to investigate the effects of randomized controlled trials on bevacizumab treatment on cancer patients. Random or fixed-effect meta-analytical models were used to evaluate the risk ratio (RR) of FAEs due to the use of bevacizumab. RESULTS: Thirty-four trials were included. Allocation to bevacizumab therapy significantly increased the risk of FAEs; the RR was 1.29 (95% CI:1.05-1.57). This association varied significantly with tumor types (P=0.002) and chemotherapeutic agents (P=0.005) but not with bevacizumab dose (P=0.90). Increased risk was seen in patients with non-small cell lung cancer, pancreatic cancer, prostate cancer, and ovarian cancer. However, FAEs were lower in breast cancer patients treated with bevacizumab. In addition, bevacizumab was associated with an increased risk of FAEs in patients who received concomitant agents of taxanes and/or platinum. CONCLUSION: Compared with chemotherapy alone, the addition of bevacizumab was associated with an increased risk of FAEs among patients with special tumor types, particularly when combined with chemotherapeutic agents such as platinum.

Metformin inhibits the growth of nasopharyngeal carcinoma cells and sensitizes the cells to radiation via inhibition of the DNA damage repair pathway.

Nasopharyngeal carcinoma (NPC) is a leading cause of cancer-related mortality. Radiotherapy is one of the primary modalities for NPC treatment. However, in patients in the late stages of the disease, the local control rate and overall survival rate remain low. Therefore, it is urgent to identify new targets that can improve the outcome of radiotherapy in this neoplasm. In the present study, we investigated the effects of metformin on the radiosensitivity of NPC cells and explored the potential mechanisms. The radiosensitizing effects of metformin on NPC cells were measured by colony formation assay. Cell apoptosis was assessed by Hoechst 33342 staining analysis. DNA damage was detected by monitoring γ-H2AX foci with immunofluorescence. The changes in apotosis-related and DNA damage repair-related proteins were detected by western blotting. Our study demonstrated that metformin significantly reduced the cell viability, enhanced radiosensitivity and potentiated radiation-induced caspase-9/-3 cleavage in the NPC cells. In addition, metformin plus radiation significantly upregulated the expression of p-ATM, p-ATR, γ-H2AX and downregulated the expression of ATM, ATR, p95/NBS1, Rad50, DNA-PK, Ku70 and Ku80. Therefore, our results suggest that metformin possesses a strong radiosensitizing potential in NPC cells. This radiosensitizing effect was associated with inhibition of DNA double-strand break repair processes through HR repair and the NHEJ repair signaling pathway, thereby enhancing radiation-induced cell apoptosis. These findings imply that metformin is a potent radiation-sensitizing agent and may be a promising candidate for clinical evaluation as part of a combined regimen for the treatment of nasopharyngeal carcinoma.