Fig. 8
Combined treatment suppresses TE7PDR xenograft growth and induces cell apoptosis in vivo. a Growth curve of TE7PDR xenografts in nude mice. Data represent as mean ± s.d., two-way ANOVA was used to compare means with Bonferroni as Post Hoc test (n = 8). **p < 0.01. b IHC staining of Ki-67 in xenograft tissues. c IHC staining of cleaved caspase-3 in xenograft tissues, magenta arrow indicates positive cells. d Comparison of Ki-67 index between vehicle and treated groups. e Quantification of cleaved caspase-3 positive cells per 2000 cells between vehicle and treated groups. All data in d and e represent as mean ± s.d., two-tailed Student t-test was used to compare means (n = 8). **p < 0.01. Scale bar, 10 μm. f Schematic illustration of the working model. In normal cells, the homeostatic regulation of Fbxo4-cyclin D1 axis keeps the downstream pathway balanced; however, in tumor cells, dysregulated Fbxo4-cyclin D1 axis suppresses Rb and hyperactivates mTORC1, leading to the imbalance between energetic production and consumption, and finally, Gln-addiction. By targeting this genetic vulnerability, combined CB-839 and metformin/phenformin disrupts the metabolic balance, leading to cell apoptosis and the suppression of cell proliferation. In addition, palbociclib-resistant ESCC cells demonstrate metabolic reprogramming characterized by Gln-addiction, resulting in increased sensitivity to combined treatment. This model provides promising therapeutic targets for cancer treatment
