Solute carrier family 35 member F2 is indispensable for papillary thyroid carcinoma progression through activation of transforming growth factor‐β type I receptor/apoptosis signal‐regulating kinase 1/mitogen‐activated protein kinase signaling axis

Solute carrier family members control essential physiological functions and are tightly linked to human diseases. Solute carrier family 35 member F2 (SLC35F2) is aberrantly activated in several malignancies. However, the biological function and molecular mechanism of SLC35F2 in papillary thyroid carcinoma (PTC) are yet to be fully explored. Here, we showed that SLC35F2 was prominently upregulated in PTC tissues at both protein and mRNA expression level compared with matched adjacent normal tissues. Besides, the high expression of SLC35F2 was significantly associated with lymph node metastasis in patients with PTC. CRISPR/Cas9-mediated knockout of SLC35F2 attenuated the tumorigenic properties of PTC, including cell proliferation, migration and invasion and induced G1 phase arrest. In contrast, ectopic expression of SLC35F2 brought about aggressive malignant phenotypes of PTC cells. Moreover, SLC35F2 expedited the proliferation and migration of PTC cells by targeting transforming growth factor-β type I receptor (TGFBR1) and phosphorylation of apoptosis signal-regulating kinase 1 (p-ASK-1), thereby activating the mitogen-activated protein kinase signaling pathway. The malignant behaviors induced by overexpression of SLC35F2 could be abrogated by silencing of TGFBR1 using a specific inhibitor. We conducted the first study on SLC35F2 in thyroid cancer with the aim of elucidating the functional significance and molecular mechanism of SLC35F2. Our findings suggest that SLC35F2 exerts its oncogenic effect on PTC progression through the mitogen-activated protein kinase pathway, with dependence on activation of TGFBR-1 and apoptosis signal-regulating kinase 1.