Ran drives pancreatic cancer metastasis by activating the osteopontin-PI3K/AKT-androgen receptor signaling cascade

Abstract

The small GTPase Ran has emerged as a key player in cancer metastasis. Our previous studies demonstrated that Ran drives pancreatic cancer metastasis by modulating androgen receptor (AR) expression. However, the detailed mechanisms by which Ran regulates AR expression remain unclear. This study aimed to elucidate the regulatory mechanisms through which Ran influences AR expression in the context of pancreatic cancer metastasis. We observed elevated levels of Ran, osteopontin (OPN), and AR in metastatic lymph node tissues, with OPN positively correlated with either Ran or AR expression. Ran silencing led to decreased levels of OPN and AR, whereas Ran upregulation increased their expression. Notably, OPN overexpression restored AR levels in Ran-silenced cells, whereas OPN knockdown diminished the inductive effect of Ran on AR expression. Additionally, OPN knockdown decreased AR expression and was associated with reduced activation of the PI3K/AKT signaling pathway. Functional assays revealed that silencing OPN significantly impaired the mobility and invasion of pancreatic cancer cells and restricted hepatic metastasis. Conversely, OPN overexpression restored the impaired metastasis caused by Ran knockdown. Furthermore, inhibiting PI3K/AKT signaling abolished the promoting effects of either Ran or OPN on pancreatic cancer metastasis. Importantly, re-expressing AR reversed the inhibitory effects of Ran or OPN silencing on the mobility and invasion of pancreatic cancer cells. In summary, Ran induces AR expression through the regulation of the OPN-PI3K/AKT signaling cascade. The Ran-OPN-PI3K/AKT-AR signaling pathway is crucial for driving pancreatic cancer metastasis.