尚不清楚功能的跨膜蛋白podoplanin（PDPN）的细胞内水平在转移性肿瘤中经常发生变化。高表达PDPN经常观察到在乳头状甲状腺癌（PTC）标本中。类似地，PTC来源的细胞系（BCPAP和TPC1，分别携带BRAF V600E突变和RET/PTC1融合），也呈现出增强的PDPN产量。我们之前报告PDPN消耗阻碍了TPC1细胞的迁移，但是促进了BCPAP细胞的转移。有趣的是，这一现象与野生型细胞的迁移方式相反，在野生型细胞中，TPC1的迁移能力高于BCPAP细胞。在这里，我们旨在阐明PDPN在调控研究过的PTC细胞的不同转移特点的分子机制方面的潜在作用。我们认为，这一现象可能是由于存在突变的BRAF等位基因或RET/PTC1融合引起的信号传导途径的替代调控。我们使用高通量RNA测序（RNA-seq）技术揭示了野生型和PDPN消耗的TPC1和BCPAP细胞中受影响的基因和信号通路。我们发现，信号通路的各种因子的表达变化，如RHOA和RAC1 GTP酶及其调控因子，与高PDPN水平和BRAF V600E突变的存在相关。我们暗示，野生型BCPAP细胞的迁移受到由于固有的高PDPN表达而对RHOA的过度激活的抑制。这个过程伴随着PI3K激酶和因此RAC1的抑制，由于RAS介导的信号传导和PTEN调控因子的过度激活。© 2023 The Authors.

The intracellular level of podoplanin (PDPN), a transmembrane protein of still unclear function, is frequently altered in metastatic tumors. High expression of PDPN is frequently observed in papillary thyroid cancer (PTC) specimens. Similarly, PTC-derived cell lines (BCPAP and TPC1, harboring the BRAF V600E mutation and RET/PTC1 fusion, respectively), also present enhanced PDPN yield. We previously reported that depletion of PDPN impairs migration of TPC1 cells, but augments metastasis of BCPAP cells. Interestingly, this phenomenon stays in contrast to the migratory pattern observed for wild-type cells, where TPC1 exhibited higher motility than BCPAP cells. Here, we aimed to elucidate the potential role of PDPN in regulation of molecular mechanisms leading to the diverse metastatic features of the studied PTC-derived cells. We consider that this phenomenon may be caused by alternative regulation of signaling pathways due to the presence of the mutated BRAF allele or RET/PTC1 fusion. The high-throughput RNA sequencing (RNA-seq) technique was used to uncover the genes and signaling pathways affected in wild-type and PDPN-depleted TPC1 and BCPAP cells. We found that changes in the expression of various factors of signaling pathways, like RHOA and RAC1 GTPases and their regulators, are linked with both high PDPN levels and presence of the BRAF V600E mutation. We imply that the suppressed motility of wild-type BCPAP cells results from overactivation of RHOA through natively high PDPN expression. This process is accompanied by inhibition of the PI3K kinase and consequently RAC1, due to overactivation of RAS-mediated signaling and the PTEN regulator.© 2023 The Authors.