Fig. 5.

APOE is negatively correlated with FTO and regulates PTC proliferation by modulating glycolysis. a Relative expression levels of APOE as determined by qRT-PCR in 100 pairs of PTC tissues and adjacent non-cancerous tissues. b FTO is negatively correlated with APOE expression as shown in 100 pairs of PTC tissues. c FTO and APOE expressions showed a significantly negative correlation in TCGA database (Obtained from starBase). d Representative photographs of IHC staining showing APOE protein expression in PTC tissues and adjacent non-cancerous tissues (Cohort 2). Scale bars: 50 μm (400X). e-f CCK-8 assay (e) and colony formation assay (f) showing proliferation ability after transfection with si-FTO or co-transfected si-FTO and si-APOE in K1 cells. g ECAR as determined by Seahorse metabolic analysis after transfection with si-FTO or co-transfection with si-FTO and si-APOE in K1 cells. h-i Glucose uptake (h) and Lactate production (i) as determined after transfection with si-FTO or co-transfection with si-FTO and si-APOE in K1 cells. j Protein expression of GLUT1, HK-II and LDHA as determined by western blotting after APOE knockdown in K1 cells. k CCK-8 assay showing proliferation ability after transfection with empty vector or APOE and simultaneous treatment with or without 2-Deoxyglucose (2-DG) in K1 cells. l Representative image of subcutaneous tumors excised from nude mice model bearing K1 cells transfected with sh-NC, sh-FTO and sh-FTO+ sh-APOE (n = 5). m-n Tumor volumes (m) and tumor weights (n) determined after excision from nude mice in the above-mentioned groups. o Representative images of ¹⁸F-FDG uptake by micro-PET imaging in sh-NC, sh-FTO and sh-FTO+ sh-APOE xenograft mouse models. Tumor glucose uptake is indicated using red circles and maximum uptake values (SUVmax) for xenografts determined by FDG-PET are shown. *P < 0.05, **P < 0.01