Inactivation of PDH can Reduce Anaplastic Thyroid Cancer Cells' Sensitivity to Artemisinin

Background: Anaplastic Thyroid Cancer (ATC) is a rare subtype of thyroid tumors with a high mortality rate. Targeted therapies against ATC are ineffective and mostly transient. Artemisinin has shown excellent anti-tumor activity in several cancers, but its effects on ATC are still unknown. Objective: To evaluate the effects of artemisinin on ATC cells and assess the mechanism underlying drug resistance. Methods: The viability and proliferation rates of the artemisinin-treated CAL-62 and BHT-101 cells were analyzed by MU and EdU incorporation assays. The protein expression levels were determined by Tandem Mass Tag (TMT) labeling quantitative proteomics and western blotting. Results: Artemisinin treatment significantly decreased the expression levels of COX2 and COX7A2 and increased that of COX14, YEM111, ALAS1, and OAT after 48h. In addition, FTL was upregulated in the CAL-62 cells and down-regulated in BHT-101 cells. The CAL-62 cells showed transient and reversible resistance to artemisinin, which was correlated to time-dependent changes in HIF1 alpha, PDK1, and PDHA levels. Conclusion: Artemisinin targets the mitochondrial respiratory chain proteins in ATC cells. CAL-62 cells show transient resistance to artemisinin via PDH downregulation, indicating that PDH activation may enhance the cytotoxic effects of artemisinin on ATC cells.