Introduction: Protein tyrosine kinase 7 (PTK7) is significantly upregulated in pancreatic cancer (PC), yet its precise molecular mechanisms in driving tumor progression remain elusive. This study investigates the regulatory interplay between PTK7, USP8, and PIK3CB in PC pathogenesis.

Methods: PTK7 mRNA and protein levels in PC cell lines were assessed using PCR and WB, respectively. Macrophage M2 polarization was evaluated by co-culturing THP-1-derived macrophages with PC cell-conditioned medium, followed by flow cytometric analysis of CD206+ cells. Co-immunoprecipitation (CoIP) assays were conducted to determine PTK7 interactions with USP8 and PIK3CB. In vivo xenograft models were utilized to assess PTK7 knockdown and PIK3CB overexpression on PC tumorigenesis.

Results: PTK7 expression was markedly elevated in PC tumor tissues and cell lines, correlating with aggressive disease phenotypes. Silencing PTK7 significantly reduced PC cell proliferation, invasion, and macrophage M2 polarization, while concurrently promoting apoptosis, indicating its critical role in tumor progression and immune evasion. Mechanistically, USP8 was identified as a key regulator of PTK7 stability through deubiquitination. Knockdown of USP8 suppressed PC cell growth and invasion, effects reversed by PTK7 overexpression, highlighting the dependence of PC cells on the USP8-PTK7 axis. CoIP assays confirmed a direct interaction between PTK7 and PIK3CB, with PIK3CB overexpression abrogating the tumor-suppressive effects of PTK7 silencing. This suggests that PTK7 exerts its oncogenic effects, at least in part, by activating PIK3CB. Further investigation revealed that USP8 positively regulates PIK3CB expression via PTK7, thereby activating the PI3K/AKT pathway, a well-established driver of cell survival, proliferation, and metastasis. In vivo studies corroborated these findings, demonstrating that PTK7 knockdown significantly impaired tumorigenesis by downregulating PIK3CB, thereby inhibiting the PI3K/AKT signaling cascade.

Conclusion: The USP8-PTK7-PIK3CB axis promotes PC progression, presenting a novel and actionable therapeutic target for intervention.