Abstract: 【Abstract】 Objective To determine the expression of glucose transporter 3 （GLUT3） in cutaneous squamous cell carcinoma （cSCC）, and to evaluate its effect on the cSCC cell line A431. Methods From June 2016 to December 2020, 22 paraffin-embedded tissue specimens were collected from patients with pathologically confirmed cSCC in the Department of Dermatology, Peking University Third Hospital, and 20 discarded normal skin tissues after dermatological surgeries served as controls. Immunohistochemical assay was performed to determine the GLUT3 expression in cSCC tissues and normal skin tissues. Cultured A431 cells were divided into two groups: GLUT3 overexpression group transfected with a lentiviral vector carrying the SLC2A3 gene, and negative control group transfected with an empty lentiviral vector. Real-time fluorescence-based quantitative PCR and Western blot analysis were conducted to determine the mRNA and protein expression of GLUT3 in A431 cells in different groups, the cell proliferation assay （MTS assay） was performed to estimate the cell proliferative activity, and the live-cell analysis system Incucyte S3 was used for real-time evaluation of the migratory and invasive abilities of A431 cells in different groups. The relative glucose consumption and lactic acid production in A431 cells at 48 hours were measured by using glucose and lactic acid assay kits, retrospectively. Two independent samples t-test was used for comparisons between two groups, and one-way analysis of variance was used for comparisons among multiple groups. Results The GLUT3 expression was significantly higher in the cSCC tissues than in the normal skin tissues （immunohistochemical assay score: 9.39 ± 2.56 points vs. 2.30 ± 2.60 points; t = 8.91, P < 0.05）. Compared with the negative control group, the mRNA and protein expression of GLUT3 markedly increased in the GLUT3 overexpression group. MTS assay showed significantly increased proliferative activity of A431 cells in the GLUT3 overexpression group compared with the negative control group after 24- and 96-hour treatment （t = 2.49, 3.54, P = 0.048, 0.012, respectively）; cell fusion rates in the scratched area were significantly higher in the GLUT3 overexpression group than in the negative control group in the cell migration assay at 6, 12 18, and 24 hours and cell invasion assay at 12, 18, and 24 hours （all P < 0.05）. At 48 hours, the relative glucose consumption and lactic acid production in A431 cells were significantly higher in the GLUT3 overexpression group than in the negative control group （t = 2.98, 2.20, P = 0.011, 0.038, respectively）. Conclusion GLUT3 was highly expressed in the cSCC tissues, and may participate in the occurrence and development of cSCC by providing energy to cSCC cells via promoting glucose uptake in cells to enhance their proliferative, migratory and invasive abilities.

Key words: Carcinoma, squamous cell, Cell proliferation, Cell migration assays, Invasion, Glucose transporter 3, A431 cells