Cpt1c regulated by AMPK promotes papillary thyroid carcinomas cells survival under metabolic stress conditions

Background: Cancer cells have to take metabolic transformation in tumor progression when facing need of increased energy and adequate vascularization. However, molecular mechanism is not fully known. In this study, we showed that expression of carnitine palmitoyltransferase 1C (Cpt1c), as a member of the gate-keeper enzymes , which transferring long-chain fatty acids into mitochondria to further oxidation, which is regulated by AMPK promotes papillary thyroid carcinomas cells survival under metabolic stress conditions. Methods: Firstly, we used qRT-PCR to detect expression of Cpt1c in papillary thyroid carcinomas tissues compared with paired normal tissues. Secondly, to evaluate whether Cpt1c is induced under metabolic stress, models of hypoxia (0.2% oxygen) and glucose deprivation for cultured papillary thyroid carcinomas cells were established. Lastly, KTC-1 cells were treated with AICAR (as an agonist of AMPK) and Compound C (as an inhibitor of AMPK) to investigate the correlation of AMPK activity with Cpt1c expression under metabolic stress. Results: Cpt1c is higher in papillary thyroid carcinomas tissues compared with paired normal tissues. Furthermore, Cpt1c up-regulation promotes cancer cell growth and metastasis. In addition, the results showed that Cpt1c expression is induced by metabolic stress, including hypoxia and low glucose treatment. Consistently, Cpt1c can protect cells from cancer cells death caused by hypoxia and low glucose. Lastly, Cpt1c expression is regulated by AMPK activity. Conclusion: Here we describe that induction of Cpt1c expression facing metabolic stress in papillary thyroid carcinomas is at least partly regulated by AMPK activity and ultimately contribute to development and progression of papillary thyroid carcinomas.