Effect of Glut-1 and HIF-1α double knockout by CRISPR/CAS9 on radiosensitivity in laryngeal carcinoma via the PI3K/Akt/mTOR pathway.

Hypoxic resistance is the main obstacle to radiotherapy for laryngeal carcinoma. Our previous study indicated that hypoxia-inducible factor 1α (HIF-1α) and glucose transporter 1 (Glut-1) double knockout reduced tumour biological behaviour in laryngeal carcinoma cells. However, their radioresistance mechanism remains unclear. In this study, cell viability was determined by CCK8 assay. Glucose uptake capability was evaluated by measurement of 18 F-fluorodeoxyglucose radioactivity. A tumour xenograft model was established by subcutaneous injection of Tu212 cells. Tumour histopathology was determined by haematoxylin and eosin staining, immunohistochemical staining, and TUNEL assays. Signalling transduction was evaluated by Western blotting. We found that hypoxia induced radioresistance in Tu212 cells accompanied by increased glucose uptake capability and activation of the PI3K/Akt/mTOR pathway. Inhibition of PI3K/Akt/mTOR activity abolished hypoxia-induced radioresistance and glucose absorption. Mechanistic analysis revealed that hypoxia promoted higher expressions of HIF-1α and Glut-1. Moreover, the PI3K/Akt/mTOR pathway was a positive mediator of HIF-1α and/or Glut-1 in the presence of irradiation. HIF-1α and/or Glut-1 knockout significantly reduced cell viability, glucose uptake and PI3K/Akt/mTOR activity, all of which were induced by hypoxia in the presence of irradiation. In vivo analysis showed that knockout of HIF-1α and/or Glut-1 also inhibited tumour growth by promoting cell apoptosis, more robustly compared with the PI3K inhibitor wortmannin, particularly in tumours with knockout of both HIF-1α and Glut-1. HIF-1α and/or Glut-1 knockout also abrogated PI3K/Akt/mTOR signalling transduction in tumour tissues, in a manner similar to wortmannin. HIF-1α and/or Glut-1 knockout facilitated radiosensitivity in laryngeal carcinoma Tu212 cells by regulation of the PI3K/Akt/mTOR pathway.

Role and mechanism of Glut-1 and H+/K+-ATPase expression in pepsin-induced development of vocal cord leukoplakia.

PURPOSE: We investigated the role of Glut-1 and H+/K+-ATPase expression in pepsin-induced development of human vocal cord leukoplakia cells (HVCLCs). Next, we analyzed the relationship between Glut-1 and H+/K+-ATPase expression with the clinicopathological features of laryngeal carcinoma. METHODS: Glut-1 and H+/K+-ATPase expression levels in HVCLCs were determined after treatment with artificial gastric juice containing pepsin and laryngeal carcinoma tissues. RESULTS: Exposure to pepsin-containing artificial gastric juice significantly enhanced the migration and proliferation of VSCLCs in a time-dependent manner. The apoptotic rate of VSCLCs decreased over time after exposure to pepsin and reached a nadir on day 7 (p < 0.01). With increasing duration of exposure to pepsin, the proportion of VSCLCs in G0/G1 phase decreased and the proportions in the S and G2/M phases significantly increased (p < 0.05). After treatment with pepsin-containing artificial gastric juice, RT-PCR and Western blotting showed that the expression of Glut-1 and H+/K+-ATPase α, ß significantly increased in HVCLCs compared to in the absence of pepsin (p < 0.05). The expression of Glut-1 and H+/K+-ATPase α, ß gradually increased from vocal cord leukoplakia (VLC) to laryngeal carcinoma (p < 0.05). Lentivirus-mediated inhibition of Glut-1 expression in VCL significantly inhibited the cells' migration and proliferation (p < 0.05) but enhanced their apoptosis (p < 0.05). Also, inhibition of Glut-1 expression resulted in an increased proportion of cells in G0/G1 phase and a significantly decreased proportion in G2/M phase (p < 0.05). CONCLUSIONS: Elevated Glut-1 expression may promote the development of VCL by upregulating laryngeal H+/K+-ATPase expression to reactivate absorbed pepsin, thus damaging the laryngeal mucosa.

The role of Glut-1 and H+/K+-ATPase expression in hyperplasia of mice laryngeal epithelium induced by pepsin.

PURPOSE: To explore the role played by Glut-1 and H+/K+-ATPase in pepsin-induced, mouse laryngeal epithelial proliferation, growth, and development. METHODS: We established a mouse model of laryngopharyngeal reflux and measured Glut-1 and H+/K+-ATPase expression levels in mouse laryngeal epithelium treated with artificial gastric juice containing pepsin. RESULTS: Artificial pepsin-containing gastric juice induced significant hyperplastic changes in mouse laryngeal epithelium compared to control mice at 15, 30, and 45 days. Inhibition of Glut-1 expression by 2-DG significantly suppressed such hyperplasia compared to mice exposed to artificial gastric juice containing pepsin at 15, 30, and 45 days. After treatment with pepsin-containing artificial gastric juice, RT-PCR and Western blotting showed that the levels of Glut-1 and H+/K+-ATPase α, ß increased significantly. CONCLUSIONS: Pepsin-containing artificial gastric juice promoted mouse laryngeal epithelial hyperplasia associated with abnormal expression of Glut-1 and H+/K+-ATPase α, ß.

Radiosensitizing effects of curcumin alone or combined with GLUT1 siRNA on laryngeal carcinoma cells through AMPK pathway-induced autophagy.

In this study, we investigated the ability of curcumin alone or in combination with GLUT1 siRNA to radiosensitize laryngeal carcinoma (LC) through the induction of autophagy. Protein levels in tumour tissues and LC cells were measured by immunohistochemistry and Western blotting. In vitro, cell proliferation, colony formation assays, cell death and autophagy were detected. A nude mouse xenograft model was established through the injection of Tu212 cells. We found that GLUT1 was highly expressed and negatively associated with autophagy-related proteins in LC and that curcumin suppressed radiation-mediated GLUT1 overexpression in Tu212 cells. Treatment with curcumin, GLUT1 siRNA, or the combination of the two promoted autophagy. Inhibition of autophagy using 6-amino-3-methypourine (3-MA) promoted apoptosis after irradiation or treatment of cells with curcumin and GLUT1 siRNA. 3-MA inhibited curcumin and GLUT1 siRNA-mediated non-apoptotic programmed cell death. The combination of curcumin, GLUT1 siRNA and 3-MA provided the strongest sensitization in vivo. We also found that autophagy induction after curcumin or GLUT1 siRNA treatment implicated in the AMP-activated protein kinase-mTOR-serine/threonine-protein kinase-Beclin1 signalling pathway. Irradiation primarily caused apoptosis, and when combined with curcumin and GLUT1 siRNA treatment, the increased radiosensitivity of LC occurred through the concurrent induction of apoptosis and autophagy.

Clinical features and hypoxic marker expression of primary sinonasal and laryngeal small-cell neuroendocrine carcinoma: a small case series.

BACKGROUND: Small-cell neuroendocrine carcinoma (SCNEC) of the head and neck is rare. The prognosis of SCNEC in the nasal cavity and larynx is poor. The aim of this study was to investigate the clinicopathological features of nasal and laryngeal SCNEC and to determine the expression of HIF-1α, GLUT-1, PI3K, and p-Akt in SCNEC. METHODS: Between 2003 and 2012, 10 consecutive patients with histologically demonstrated nasal and laryngeal SCNEC were enrolled. Clinicopathological materials and follow-up data were analyzed retrospectively. Immunohistochemistry was used to detect GLUT-1, HIF-1α, PI3K, and p-Akt expression in paraffin wax-embedded tumor specimens. RESULTS: The subjects were eight males and two females with a mean age of 60.8 (range: 53 to 71) years. Tumors were located in the maxillary sinus (n = 3) and larynx (n = 7). At last follow-up, four patients (40.0%) had local recurrence and five patients (50.0%) had developed distant metastases. Six patients died. The mean overall survival was 19.3 ± 2.1 months. Expression of GLUT-1, HIF-1α, PI3K, and p-Akt was seen in sinonasal and laryngeal SCNEC in 80 (8 out of 10), 50 (5 out of 10), 40 (4 out of 10), and 40% (4 out of 10) of cases, respectively. Expression of GLUT-1, HIF-1α, PI3K, and p-Akt was higher in sinonasal and laryngeal SCNEC than in precancerous lesions. CONCLUSIONS: Primary sinonasal and laryngeal SCNEC is rare. This paper presents 10 cases of sinonasal and laryngeal SCNEC with more common local recurrence and distant metastasis. HIF-1α, GLUT-1, PI3K, and p-Akt expression was higher in sinonasal and laryngeal SCNEC than in precancerous lesions.

Anticancer mechanism of apigenin and the implications of GLUT-1 expression in head and neck cancers.

Apigenin, a natural phytoestrogen flavonoid, has potential biological effects, including antioxidative, anti-inflammatory and anticancer activities. The mechanisms of anticancer activities of apigenin are unknown. Some studies have found that apigenin inhibits GLUT-1 mRNA and protein expression in cancer cells. Thus, we hypothesized that apigenin exerts similar effects on head and neck cancers through its inhibition of GLUT-1 expression. In this article, we review the anticancer mechanism of apigenin and the implications of GLUT-1 expression in head and neck cancers. In addition, we describe the current state of knowledge about the relationship between apigenin and GLUT-1 expression in head and neck cancers.

Effect of antisense oligodeoxynucleotides glucose transporter-1 on enhancement of radiosensitivity of laryngeal carcinoma.

PURPOSE: Laryngeal carcinomas always resist to radiotherapy. Hypoxia is an important factor in radioresistance of laryngeal carcinoma. Glucose transporter-1 (GLUT-1) is considered to be a possible intrinsic marker of hypoxia in malignant tumors. We speculated that the inhibition of GLUT-1 expression might improve the radiosensitivity of laryngeal carcinoma. METHODS: We assessed the effect of GLUT-1 expression on radioresistance of laryngeal carcinoma and the effect of GLUT-1 expressions by antisense oligodeoxynucleotides (AS-ODNs) on the radiosensitivity of laryngeal carcinoma in vitro and in vivo. RESULTS: After transfection of GLUT-1 AS-ODNs: MTS assay showed the survival rates of radiation groups were reduced with the prolongation of culture time (p<0.05); Cell survival rates were significantly reduced along with the increasing of radiation dose (p<0.05). There was significant difference in the expression of GLUT-1mRNA and protein in the same X-ray dose between before and after X-ray radiation (p<0.05). In vivo, the expressions of GLUT-1 mRNA and protein after 8Gy radiation plus transfection of GLUT-1 AS-ODNs were significant decreased compared to 8Gy radiation alone (p<0.001). CONCLUSION: Radioresistance of laryngeal carcinoma may be associated with increased expression of GLUT-1 mRNA and protein. GLUT-1 AS-ODNs may enhance the radiosensitivity of laryngeal carcinoma mainly by inhibiting the expression of GLUT-1.

Poor outcome of comprehensive therapy in a case of laryngeal synovial sarcoma.

BACKGROUND: Synovial sarcoma is common in the extremities. Our search revealed only 17 cases of synovial sarcoma of the larynx in the English-language literature. CASE REPORT: We report an additional case of a 37-year-old man with primary laryngeal synovial sarcoma who underwent positron emission tomography/computed tomography (PET/CT) following the treatment. Although the patient received comprehensive therapy including surgery, radiotherapy, repeated chemotherapies, and targeted therapies, he had an unfavourable outcome and died of distant metastases. CONCLUSIONS: In synovial sarcoma of the larynx, PET/CT can detect recurrence and metastasis. PET/CT can also predict the treatment effect in patients with synovial sarcoma.

Multiple Thyroglossal Duct Cysts: Clinical Experience and Literature Review.

Thyroglossal duct cysts (TDCs) are generally single cyst, multiple TDCs are rare. We describe a case of multiple TDCs, discuss its characteristic features and management, and provide a review of the literature, to improve clinical diagnosis and treatment. We report an extremely rare case of multiple TDCs containing five cysts, together with a review of the relevant English medical literature. To the best of our knowledge, this is the first reported case of TDCs containing more than three cysts in the anterior cervical region. The five cysts were completely excised in a Sistrunk operation. Histological examination of the cystic lesions revealed TDCs. The patient recovered well and no recurrence was found during the 6-year of follow-up. Multiple TDCs are extremely rare, and may be misdiagnosed as a single cyst. Clinicians should be aware of the possibility of multiple thyroglossal duct cysts. Adequate preoperative radiological examinations should be performed, and careful interpretation of the CT or MRI scans is important to diagnosis and surgery.

Pepsin Increases the Proliferation of Vocal Cord Leukoplakia Epithelial Cells by Inducing Autophagy.

OBJECTIVE: To investigate the role of H+ /K+ ATPase in the proliferation of pepsin-induced vocal cord leukoplakia (VCL) cells. STUDY DESIGN: Translation research. SETTING: Affiliated Hospital of University. METHODS: Immunohistochemistry was used to detect pepsin, H+ /K+ ATPase (ATP4A and ATP4B subunits) in VCL cells with varying degrees of dysplasia. After primary cultures of VCL cells had been established, the effects of acidified pepsin on the proliferation, autophagy, and H+ /K+ -ATPase distribution of VCL cells were investigated. RESULTS: The levels of pepsin, ATP4A, and ATP4B were significantly higher in VCL tissue with moderate-to-severe dysplasia than in normal tissue (p < .05); these levels gradually increased according to dysplasia severity. The expression levels of ATP4A and ATP4B were significantly correlated with the amount of pepsin in VCL cells (p < .01). Acidified pepsin enhanced the levels of proliferation and autophagy in human VCL epithelial cells. The cloning- and autophagy-promoting effects of acidified pepsin on VCL cells were partially reversed by pantoprazole; these effects were completely blocked by the autophagy inhibitor chloroquine. Finally, acidified pepsin promoted the colocalization of H+ /K+ -ATPase and lysosomes in VCL cells; it also mediated lysosome acidification. CONCLUSION: Pepsin and H+ /K+ -ATPase may contribute to the progression of VCL. Specifically, acidified pepsin may regulate lysosome acidification by promoting lysosomal localization of H+ /K+ -ATPase.

Angioleiomyoma of the Epiglottis Mimicking Epiglottic Hemangioma: Clinical Experience and Literature Review.

We describe a case of laryngeal angioleiomyoma, discuss its characteristic features and management, and provide a review of the literature, to improve clinical diagnosis and treatment. We report the oldest patient with a laryngeal angioleiomyoma to date and analyze the clinicopathological features reported in the literature. To the best of our knowledge, a total of 36 cases have been described in the English and Chinese medical literature (including our case). The male-to-female ratio was 5:1 and the mean age was 53.89 years. The most common laryngeal site was the supraglottic region (23 cases; 63.89%), followed by the subglottic region (8 cases; 22.22%), and glottis (5 cases; 13.89%). The most common and serious intra- and postoperative complication was massive bleeding. Angioleiomyoma is a benign tumor that rarely occurs in the larynx. Biopsy of this lesion should not be performed; complete surgical resection is the best treatment. Recurrence and malignant transformation are extremely rare.

Thyroglossal duct cyst with hoarseness as the sole symptom and an intralaryngeal extension masquerading as a laryngeal mass: Clinical experience and literature review.

A thyroglossal duct cyst is the most common congenital disease in the neck. There are two age groups usually associated with thyroglossal duct cysts: 1-11 years in children and 30-60 years in adults. These midline neck masses are typically located anteriorly in the neck, inferior to the hyoid bone. We report an extremely rare case of an intralaryngeal thyroglossal duct cyst without a neck mass, presenting with hoarseness as the sole symptom. A 64-year-old man presented with a 3-month history of hoarseness. On physical examination, no neck mass or swelling was observed during cervical palpation. Laryngostroboscopy revealed a large submucosal mass in the right glottis and supraglottis, and mobility of the right vocal cord was restricted. Surgery was performed via an external approach to completely resect the cyst, together with the middle part of the hyoid bone. Histopathologic examination of the cyst led to a diagnosis of thyroglossal duct cyst. The patient recovered well and his voice returned to normal. Attention should be paid to the occurrence of rare types of thyroglossal duct cyst in unusual clinical sites. Adequate radiological examinations should be performed, and reading the computed tomography or magnetic resonance imaging scans carefully before surgery is important to avoid misdiagnosis.

Fibroblast-epithelial metabolic coupling in laryngeal cancer.

OBJECTIVES: To explore the Fibroblast-epithelial metabolic coupling among laryngeal cancers and its prognostic roles METHODS: We reviewed the clinical information of patients with laryngeal cancer in our department. Paraffin-embedded tissues from included patients were immune-stained with antibodies towards MCT4 and TOMM20 and evaluated for stromal and epithelial expression. Survival analysis and Cox regression analysis were applied to investigate the prognostic factor of laryngeal squamous cell carcinoma. TCGA database was used to validate our result. RESULTS: Stromal MCT4 and TOMM20 were both significantly associated with each other among laryngeal cancer tissues. High expression of both Stromal MCT4 and TOMM20 is related to poor prognosis in laryngeal cancer. Stromal MCT4 expression was an independent prognostic indicator for laryngeal cancer. Furthermore, cancer cell MCT4 expression has no relationship with the clinical characteristics of laryngeal cancer. CONCLUSIONS: Our results support that the phenomenon of metabolic symbiosis was exist in the laryngeal cancer tissue. In addition, TOMM20 and stromal MCT4 could be used as new therapeutic targets for laryngeal cancer.

Transcervical Exploration via the Posterolateral Approach to Extract a Fishbone Embedded in the Paraglottic Space.

Ingested foreign bodies occasionally migrate to the paraglottic space. The external transcervical approach is almost always required to extract completely embedded foreign bodies. We report a case of an ingested fishbone embedded in the paraglottic space, which was successfully removed through transcervical exploration of the paraglottic space via the posterolateral approach. The posterolateral approach is safe and effective for the removal of foreign bodies completely embedded in the paraglottic space.

Relationship Between Pepsin Expression and Dysplasia Grade in Patients With Vocal Cord Leukoplakia.

OBJECTIVE: To measure pepsin expression in patients with vocal fold leukoplakia and elucidate its clinical significance. STUDY DESIGN: Retrospective analysis of pathologic archive specimens. SETTING: Affiliated university hospital. SUBJECTS AND METHODS: The study included 45 patients with vocal fold leukoplakia and 19 with vocal fold polyps who underwent surgical treatment between December 2013 and July 2016. Masses were detected on both vocal cords in 5 patients with vocal fold leukoplakia and in 1 patient with vocal fold polyps. Immunohistochemistry was used to assess pepsin expression. In addition, the relationship of pepsin expression level with clinical characteristics of vocal fold leukoplakia was assessed. RESULTS: The rate of pepsin expression was high in the polyp group (75%) and the leukoplakia group (68%); however, the difference between groups was not significant (P > .05). Pepsin expression significantly increased according to grade of dysplasia (mild, 57.1%; moderate, 88.9%; severe, 100.0%; P = .034). Similarly, the percentage of lesions that exhibited strongly positive pepsin expression increased with the grade of dysplasia (mild, 37.1%; moderate, 66.7%; severe, 100.0%; P = .005). The leukoplakia recurrence rate was higher in patients with positive pepsin expression than in patients with negative pepsin expression but without a significant difference (P > .05). CONCLUSION: Our study suggests that pepsin was associated with the grade of dysplasia of vocal cord leukoplakia. Further investigation with appropriate control groups and controlling for other risk factors, such as smoking or alcohol consumption, is needed.

Epstein-Barr Virus-Positive Langerhans Cell Sarcoma: Is There a Link? A Case Report.

Langerhans cell sarcoma (LCS) is an extremely rare, malignant neoplasm that originates from Langerhans cells (LCs). Fewer than 70 cases have been reported in the English-language literature. LCS typically involves multiple organs, including the skin, lymph nodes, lungs, bone, bone marrow, liver, spleen, and soft tissues. Several etiological factors for LCS have been proposed, including immunosuppression, virus infection, and prior hematological disease. We report a rare case of LCS with Epstein-Barr virus (EBV) infection; bilateral cervical giant cysts were the initial manifestation. To our knowledge, this is the first report of LCS with EBV infection. The case information was complete, and the relevant literature was reviewed to gain insight into LCS. The case raises new questions on the oncogenic character of EBV.

Pump Proton and Laryngeal H+/K+ ATPases.

PURPOSE: The presence of extra-gastric H+/K+ ATPases may explain the clinically significant effect of proton pump inhibitor (PPI) pharmacotherapy in patients with chronic laryngitis related to laryngopharyngeal reflux disease (LPRD) but without gastroesophageal reflux disease (GERD) symptoms. Given the need for a better understanding of GERD and LPRD, we review the various proton pumps with respect to their classification, function, and distribution. We then consider the potential role of the laryngeal H+/K+ ATPase pump in LPRD. METHODS: We searched databases of PubMed, EMBASE, and Web of Science to achieve related published before September 15, 2020. RESULTS: There were only seven English-literatures meeting inclusive criteria about laryngeal H+/K+ ATPases. Some studies provide convincing evidence of a laryngeal H+/K+ ATPase in normal laryngeal tissues but also suggest the potential role of the proton pump in the abnormal mucus secretion frequently seen in patients with chronic laryngitis. CONCLUSION: A laryngeal H+/K+ ATPase expresses in normal laryngeal tissues. These findings question the current understanding of GERD and LPRD.

Gastric H+/K+-ATPase Expression in Normal Laryngeal Tissue and Laryngeal Carcinoma.

BACKGROUND: Several studies have suggested that laryngopharyngeal reflux disease (LPRD) or gastroesophageal reflux disease (GERD) is an independent risk factor for laryngeal carcinoma. However, it remains unclear whether either condition affects the level of H+/K+-ATPase expression in laryngeal carcinoma. MATERIALS AND METHODS: Immunohistochemistry, real-time RT-PCR, and Western blotting were used to explore the distributions of proton pump (H+/K+-ATPase) α- and ß-subunits in normal laryngeal tissue and laryngeal carcinoma. RESULTS: Messenger RNAs encoding both the α- and ß-subunits were found in the normal epiglottic, ventricular fold, vocal fold, and arytenoid mucosae, as well as epiglottic cartilage. The distributions and expression levels of H+/K+-ATPase α-subunits in various laryngeal subregions did not significantly differ in IHC, RT-PCR, or Western blotting. However, Western blotting revealed a significant difference between the expression level of the ß-subunit protein in the epiglottic cartilage and the levels in other sites. The expression levels of both subunits were significantly higher in carcinomatous than in paracarcinomatous tissue and normal laryngeal tissue. The mean follow-up duration was 66.2 months (range, 17-162 months). In all, 4 patients died during follow-up, 4 were lost to follow-up, and 22 were alive and free of disease at the end of follow-up. Two patients developed lung metastases and six developed disease recurrences (at 2, 8, 14, 16, 36, and 41 months). The 3- and 5-year overall survival (OS) rates were 93.0% and 77.0%, respectively. Univariate analyses showed that the 5-year OSs were significantly associated with the T, N, and clinical stages but not with age, alcohol use, pathological differentiation, or the expression levels of the α- or ß-subunits (as revealed by IHC, RT-PCR, or Western blotting). However, in multivariate regression analyses, the 5-year OSs were not significantly associated with any clinicopathological factor or the expression levels of either subunit. CONCLUSION: H+/K+-ATPase is expressed in the normal larynx, including in the epiglottic cartilage and the mucosae of the epiglottis, ventricular fold, and arytenoid vocal fold. The expression levels of the H+/K+-ATPase α- and ß-subunits in laryngeal carcinomas were higher than in normal laryngeal tissues.

Effect of combination of curcumin and GLUT-1 AS-ODN on radiosensitivity of laryngeal carcinoma through regulating autophagy.

BACKGROUND: This study is to explore the role of curcumin and GLUT-1 antisense oligodeoxynucleotides (AS-ODN) on autophagy modulation-initiated radiosensitivity. METHODS: BALB/c mice were employed to establish xenograft model using Tu212 cell. The expression of autophagy- and apoptosis-related proteins was determined by WB. Autophagosome was observed under transmission electron microscope. Apoptosis of tumor tissue were detected by TUNEL staining. RESULTS: Combinations of curcumin and GLUT-1 AS-ODN with 10 Gy inhibited the tumor growth by inducing apoptosis of laryngeal cancer cells followed with the enhancement of autophagy. 3-MA also had a promotion effect on irradiation-mediated growth inhibition possibly by depressing PI3K and on curcumin/GLUT-1 AS-ODN-mediated growth inhibition potentially by regulating autophagic events. Of note, a de-escalation of radiotherapy dose (5 Gy) along with curcumin, GLUT-1 AS-ODN or 3-MA produced a stronger effect than high dosage of radiotherapy (10 Gy) alone. CONCLUSIONS: Curcumin and GLUT-1 AS-ODN improve the radiosensitivity of laryngeal carcinoma through regulating autophagy and inducing apoptosis.

GLUT-1 siRNA Enhances Radiosensitization Of Laryngeal Cancer Stem Cells Via Enhanced DNA Damage, Cell Cycle Redistribution, And Promotion Of Apoptosis In Vitro And In Vivo.

BACKGROUND: Radiotherapy does not show good efficacy against laryngeal cancer due to radioresistance. Cancer stem cells (CSCs) are considered among the causes of radioresistance. Inhibition of glucose transporter-1 (GLUT-1) using GLUT-1 small interfering RNA (siRNA) may enhance the radiosensitivity of laryngeal cancer cells, but the underlying cellular mechanisms remain unclear. METHODS: The CD133+-Hep-2R cell line was established with repeated irradiation and magnetic-activated cell sorting. The effects of irradiation on CD133+-Hep-2R cells were examined by CCK-8 assay, Transwell assay, quantitative real-time polymerase chain reaction (RT-PCR), and Western blotting. The effects of GLUT-1 siRNA on the radiosensitivity of CD133+-Hep-2/2R cells were examined by RT-PCR, Western blotting, CCK-8 assay, colony formation assay, and Transwell assay in vitro and in a xenograft tumor model in nude mice. The cellular mechanism of enhanced radiosensitivity associated with GLUT-1 siRNA was investigated. The cell cycle and apoptosis rate were analyzed by flow cytometry, and the repair capability was examined by determining the levels of RAD51 and DNA-PKcs. RESULTS: CD133+-Hep-2/2R cells showed stronger proliferation, lower apoptosis rate, lower percentage of G0/G1 phase cells, higher percentages of S and G2/M phase cells, and higher expression levels of GLUT-1 than Hep-2/2R cells. Transfection with GLUT-1 siRNA inhibited the proliferation and invasive capability of CD133+-Hep-2R cells by inhibiting GLUT-1 expression, which also caused a redistribution of the cell cycle (higher proportion of cells in the G0/G1 phase and lower proportion in the S and G2/M phases), increased the apoptosis rate, and reduced DNA repair capability by suppressing RAD51 and DNA-PKcs expression. CONCLUSION: The results of this study suggest that GLUT-1 siRNA can enhance the radiosensitivity of CD133+-Hep-2R cells by inducing a redistribution of cell cycle phases, inhibiting DNA repair capability, and increasing apoptosis. Inhibition of GLUT-1 may have therapeutic potential for interventions to increase the radiosensitivity of laryngeal CSCs.