Effect of AMPK pathway on apoptosis of human thyroid papillary cancer B-CPAP cells under low glucose and hypoxia conditions through CPT1c regulated by PPARα / 中国肿瘤生物治疗杂志

ABSTRACT

@#[Abstract] Objective: To investigate the mechanisms of carnitine palmitoyltransferase 1c (CPT1c) expression to affect the proliferation and apoptosis of human thyroid papillary cancer B-CPAP cells through the AMP-dependent/activated protein kinase (AMPK) pathway in the low glucose and hypoxic conditions. Methods: Firstly,humanthyroidpapillarycarcinomaB-CPAP cells were cultured under normal condition or low glucose and hypoxic condition respectively, followed with the treatment of AMPK inhibitor compound C. Western blotting was used to detect the expressions of AMPK, p-AMPK, peroxisome proliferator-activated receptor α (PPARα) and CPT1c; the proliferation and apoptosis were detected by CCK-8 and Flow cytometry, respectively. Then PPARα-siRNA was synthesized and transfected into B-CPAP cells to knock down PPARα, and then the cells were cultured under normal or low glucose and hypoxic condition respectively.Above indicators were also detected to verify the regulation of PPARα on CPT1c. Finally, the human luciferase reporter plasmid containing CPT1c gene promoter was constructed, and the effect of PPARα on the activity of CPT1c promoter luciferase activity was observed by immunofluorescence. Results: The expressions ofAMPK, p-AMPK, PPARα and CPT1c were significantly increased in B-CPAP cells under low glucose and hypoxia condition (P<0.05 or P<0.01), while cell proliferation and apoptosis rate did not change significantly (P>0.05). After the treatment of AMPK inhibitor compound C, the expressions of p-AMPK, PPARα and CPT1c in low glucose and hypoxia group were significantly decreased (P<0.05 or P<0.01), the inhibitory rate on cell proliferation and apoptosis rate were significantly increased (P<0.05). However, the change range was smaller than that in the normal culture + compound C group (P<0.05).After PPARα knockdown, the expressions ofAMPK, p-AMPK, PPARα and CPT1c in cancer cells cultured under normal conditions were significantly decreased (P<0.05 or P<0.01), and the inhibitory rate on cell proliferation and apoptosis rate were significantly increased (P<0.05). While under low glucose and hypoxia condition, the expression of CPT1c in cells after transfection was significantly decreased (P<0.05), and the inhibition rate on cell proliferation and the apoptosis rate were significantly increased (P<0.05); However, the change range was still lower than that of normal condition group after transfection (P<0.05).After PPARα overexpression, the ratio of fluorescence in the empty vector group was not significantly different from that of the blank group (P>0.05), and the ratio of fluorescence was significantly increased in PPARα over-expression group (P<0.05). Conclusions: AMPK can increase the expression of PPARα to promote the expression of CPT1c in thyroid cancer B-CPAP cells under low glucose and hypoxia conditions, thereby inhibiting cell apoptosis and maintaining cell proliferation ability.