To explore the mechanism of the inhibitory effects of plumbagin on the malignant biological behaviors and glycolysis of tongue squamous cell carcinoma cells through fibronectin type Ⅲ domain-containing protein 3B (FNDC3B).

Human tongue squamous cell carcinoma cells (TCA8113) in the logarithmic growth phase were obtained. TCA8113 cells were divided into blank group (normal cultured), experimental-L, M, and H group (TCA8113 cells were treated with 1, 2 and 4 μmol·L^-1 plumbagin), oe-NC group (TCA8113 cells were transfected with the negative control plasmid oe-NC), oe-FNDC3B group (TCA8113 cells were transfected with oe-FNDC3B), experimental-H+oe-NC group (based on experimental-H group, transfected with the oe-NC plasmid) and experimental-H+oe-FNDC3B group (based on experimental-H group, transfected with the oe-FNDC3B plasmid). Real-time quantitative polymerase chain reaction was used to detect FNDC3B mRNA relative expression levels. Cell viability was assessed using the methylthiazolyldiphenyl-tetrazolium bromide (MTT) assay. Cell invasion was evaluated using the Transwell assay. Immunofluorescence staining was performed to detect the protein relative expression levels of FNDC3B, hexokinase 2 (HK2) and lactate dehydrogenase A (LDHA). Cell apoptosis was detected using the terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay.

The numbers of invasive cells in blank group, experimental-H group, experimental-H+oe-NC group and experimental-H+oe-FNDC3B group were (89.71±13.59), (69.67±14.78), (62.33±10.11) and (158.23±20.95), respectively; the apoptosis rates were (10.07±2.41)%, (23.38±4.75)%, (20.65±5.43)% and (8.44±1.18)%, respectively; the relative expression levels of HK2 were 1.00±0.15, 0.58±0.09, 0.55±0.07 and 0.71±0.10, respectively; the relative expression levels of LDHA were 1.00±0.12, 0.63±0.11, 0.61±0.09 and 0.89±0.15, respectively; the relative expression levels of P53 were 1.00±0.15, 1.59±0.31, 1.64±0.28 and 1.25±0.22, respectively; the relative expression levels of P21 were 1.00±0.13, 1.51±0.26, 1.48±0.19 and 1.19±0.17, respectively; the relative expression levels of CDK6 were 1.00±0.13, 0.28±0.04, 0.33±0.06 and 0.79±0.12, respectively. There were statistically significant differences in the above indicators between experimental-H group and blank group, and between experimental-H+oe-FNDC3B group and experimental-H+oe-NC group (all P<0.05).

Plumbagin may promote the apoptosis of tongue squamous cell carcinoma cells, and inhibit the invasion and glycolysis of cancer cells by regulating the P53/P21/CDK6 signaling pathway through FNDC3B.