Intrinsic cancer cell phosphoinositide 3-kinase regulates fibrosis and vascular development in cholangiocarcinoma

Background & AimsThe class I- phosphatidylinositol-3 kinases (PI3Ks) signalling is dysregulated in almost all human cancers whereas the isoform-specific roles remain poorly investigated. We reported that the isoform delta (PI3K delta) regulated epithelial cell polarity and plasticity and recent developments have heightened its role in hepatocellular carcinoma (HCC) and solid tumour progression. However, its role in cholangiocarcinoma (CCA) still lacks investigation.Approach & ResultsImmunohistochemical analyses of CCA samples reveal a high expression of PI3K delta in the less differentiated CCA. The RT-qPCR and immunoblot analyses performed on CCA cells stably overexpressing PI3K delta using lentiviral construction reveal an increase of mesenchymal and stem cell markers and the pluripotency transcription factors. CCA cells stably overexpressing PI3K delta cultured in 3D culture display a thick layer of ECM at the basement membrane and a wide single lumen compared to control cells. Similar data are observed in vivo, in xenografted tumours established with PI3K delta-overexpressing CCA cells in immunodeficient mice. The expression of mesenchymal and stemness genes also increases and tumour tissue displays necrosis and fibrosis, along with a prominent angiogenesis and lymphangiogenesis, as in mice liver of AAV8-based-PI3K delta overexpression. These PI3K delta-mediated cell morphogenesis and stroma remodelling were dependent on TGF beta/Src/Notch signalling. Whole transcriptome analysis of PI3K delta using the cancer cell line encyclopedia allows the classification of CCA cells according to cancer progression.ConclusionsOverall, our results support the critical role of PI3K delta in the progression and aggressiveness of CCA via TGF beta/src/Notch-dependent mechanisms and open new directions for the classification and treatment of CCA patients.