Background: Glucose transporter (GLUT)-mediated glucose uptake is an important process in the development of laryngeal carcinoma, one of the most common malignancies of the head and neck. GLUT-1, together with HIF-1α, is also an indicator of hypoxia. Both proteins play a critical role in glucose uptake and glycolysis in laryngeal carcinoma cells under hypoxic stress. A double gene knockout model in which HIF-1α  and GLUT-1  are no longer expressed can provide important information about carcinogenesis in laryngeal carcinoma. 
Purpose: In this study we used the CRISPR/Cas 9 system to induce HIF-1α and GLUT-1 double gene knockout in HEp-2 cells and then used the knocked-out cells to study the role of these markers in laryngeal carcinoma, including in chemo-radioresistance.
Methods: High-grade small-guide RNAs (sgRNAs) of HIF-1α and GLUT-1 were designed using an online tool and inserted into the pUC57-T7-gRNA vector. The recombinant plasmids were transfected into HEp-2 cells and positive cells were screened using the dilution method. Gene mutation and expression were determined by sequence analysis and immunoblotting.
Results: In HIF-1α and GLUT-1 double gene knockout HEp-2 cells, a 171-bp deletion in the HIF-1α  genomic sequence was detected, whereas multiple base insertions resulted in frameshift mutations in the GLUT-1  gene. Neither HIF-1α nor GLUT-1 protein was expressed in positive cells. The proliferation, migration, and invasion of HEp-2 cells were significantly decreased afterward. The possible mechanism may be that the inhibition PI3K/AKT/mTOR pathway by HIF-1α and GLUT-1double gene knockout using CRISPR/Cas9 technique lead to reduction of glucose uptake and lactic acid generation.
Conclusion: Our HIF-1α  and GLUT-1  double gene knockout HEp-2 cell model, obtained using a CRISPR/Cas9-based system, may facilitate studies of the pathogenesis of laryngeal carcinoma.
Keywords: CRISPR, Cas9 system, glucose transporter-1, HEp-2 cells, hypoxia-inducible factor-1α, PI3K, AKT, mTOR pathway, laryngeal carcinoma