Abstract: Objective To observe the effect of high-mobility group box-1 protein (HMGB1) on the proliferation of human
nasopharyngeal carcinoma cell line C666-1 and explore the possible underlying mechanisms. Methods Cultured C666-1 cells
were treated with a siRNA targeting HMGB1 gene. The changes in the cell proliferation were detected by CCK8 analysis, the
cell cycle distribution was assayed with flow cytometry, and the expressions of cyclin D1, CDK6 and related pathway proteins
were detected with Western blotting. The effect of a HMGB1 plasmid carrying the reporter gene GFP on the proliferation of
C666-1 cells was tested with CCK8 and EDU analysis. Results Compared with the control cells, the cells transfected with the
siRNA targeting HMGB1 showed obviously suppressed cell proliferation (P<0.001), cell cycle arrest in G1 phase (P<0.001), and
down-regulated expressions of cyclin D1, CDK6, STAT3 and P-STAT3. Overexpression of HMGB1 in cells transfected with the
HMGB1 plasmid showed a significantly increased ratio of S phase cells (P<0.05) and obviously enhanced cell proliferation (P<
0.001). Conclusion HMGB1 can promote the proliferation of human nasopharyngeal carcinoma cell line C666-1 by upregulating
cyclin D1 and CDK6 via the STAT3 signaling pathway.