Hypoxia‑induced miR‑135b‑5p promotes neuroendocrine differentiation of prostate cancer cells through HIF1AN‑HIF1α axis

Neuroendocrine prostate cancer (NEPC) is a highly aggressive subtype of prostate cancer (PCa), associated with poor prognosis and resistance to androgen receptor (AR)‑targeted therapies. Hypoxia is a well‑established driver of lineage plasticity and has been implicated in promoting NE differentiation (NED) of tumors. However, the underlying molecular mechanisms linking hypoxia to NED remain unclear. In the present study, miR‑135b‑5p was identified as a critical regulator of hypoxia‑induced NED through modulation of the hypoxia‑inducible factor alpha‑1 subunit alpha inhibitor (HIF1AN)‑HIF1α axis. Exposure of androgen‑dependent PCa cell lines (LNCaP and VCaP) to hypoxia induced neurite outgrowth and increased expression of NE markers, concurrent with upregulation of miR‑135b‑5p. Target prediction followed by experimental validation in luciferase reporter assays confirmed that HIF1AN is a direct target of miR‑135b‑5p. Suppression of HIF1AN results in the stabilization of HIF1α, which in turn activates the AKT/mTOR signaling pathway, facilitating NE trans differentiation. Functional studies demonstrated that overexpression of miR‑135b‑5p by mimics promotes NED in LNCaP cells, while inhibition of miR‑135b‑5p reverses the NE features in NE‑LNCaP and NCI‑H660, NE cells. Furthermore, pharmacological inhibition of HIF1α using PX‑478 abrogated hypoxia‑induced NED and attenuated activation of AKT/mTOR signaling, further underscoring the significance of the miR‑135b‑5p‑HIF1AN‑HIF1α axis in NED of PCa cells. Collectively, the findings of the present study reveal a novel miR‑135b‑5p‑HIF1AN‑HIF1α signaling axis that is involved in hypoxia‑induced NED via AKT/mTOR activation and identify miR‑135b‑5p and HIF1α as potential therapeutic targets for NEPC.