We aimed to explore the role of lenvatinib-mediated autophagy in papillary thyroid cancer (PTC). K1 and BCPAP, were tested for cell viability, proliferation, and apoptosis after treatment with lenvatinib or chloroquine (CQ) or both. The levels of angiogenesis vascular endothelial growth factor A (VEGFA) were measured by ELISA. Transwell and wound-healing assays were performed using endothelial HUVECs cells. The dynamics of microvessels were detected by tubular formation assay. Western blotting was used to determine the expression of LC3-I/II and Atg-7 and alterations in the PI3K/Akt/mTOR and MEK/ERK pathways. In vivo tumor growth assay and immunohistochemical staining (IHC) was also performed. The results showed that lenvatinib inhibited the viability of K1 and BCPAP cells and caused apoptosis. We further showed that lenvatinib also upregulated autophagy levels in thyroid cancer cells in a dose-dependent manner through the PI3K/Akt/mTOR and MEK/ERK pathways. Co-administration of lenvatinib with CQ resulted in a greater decrease of VEGFA in the tumor supernatant than with either lenvatinib or CQ alone. Autophagy inhibition enhanced the cytotoxicity and anti-angiogenic ability of lenvatinib, which was supported by the HUVECs migration, wound healing, and tube formation assays. Inhibiting autophagy chemically or genetically enhanced lenvatinib's cytotoxic effects and anti-angiogenic efficacy in thyroid cancer cells in vitro and in vivo. In conclusion, lenvatinib inhibited cell viability and induced apoptosis and autophagy in human PTC cells. Significantly, the combination of lenvatinib and autophagy inhibition may represent a novel and effective treatment option for PTC, which may be able to overcome drug resistance.
Keywords: Lenvatinib; PTC; VEGFA; anti-angiogenesis; autophagy.
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