Work

SPP1 promotes anoikis resistance and metastatic phenotypes in hepatocellular carcinoma through PI3K-sensitive signaling

Year: 2026

Type: article

Abstract: Background Anoikis resistance enables tumor cells detached from the extracellular matrix to survive during metastatic dissemination, yet its relationship with the immune microenvironment of hepatocellular carcinoma (HCC) remains incompletely understood. Secreted phosphoprotein 1 (SPP1), which encodes osteopontin (OPN), has been implicated in HCC progression. This study investigated the role of SPP1 in anoikis resistance and metastatic phenotypes and evaluated the clinical relevance of circulating OPN in HCC. Methods SPP1 was prioritized through integrated analyses of TCGA-LIHC data, including differential expression, survival association, intersection with anoikis-related genes, and pathway enrichment, followed by characterization of the associated tumor microenvironment. Single-cell transcriptomic analysis was performed to determine the cellular distribution of SPP1 and infer potential intercellular communication. SPP1 expression was validated in HCC tissues and cell lines. Gain- and loss-of-function experiments assessed cell viability, clonogenic growth, migration, invasion, and apoptosis under poly-HEMA suspension. The involvement of PI3K signaling was examined using LY294002. Subcutaneous xenograft and experimental pulmonary colonization models were used to evaluate in vivo phenotypes. Serum OPN and alpha-fetoprotein (AFP) were measured in 58 patients with HCC and 36 healthy controls. Results SPP1 was upregulated in HCC and associated with shorter overall survival. Tumors with high SPP1 expression exhibited a myeloid- and stroma-enriched microenvironmental profile. Single-cell analysis identified prominent SPP1 expression in myeloid populations and inferred potential SPP1-mediated communication between macrophage subsets and malignant hepatocytes. Increased SPP1 expression was independently confirmed in HCC tissues and cell lines. SPP1 overexpression enhanced cell viability, clonogenic growth, migration, invasion, and resistance to suspension-induced apoptosis, whereas SPP1 silencing produced reciprocal effects. LY294002 attenuated SPP1-induced AKT activation, anoikis resistance, motility, and mesenchymal-marker expression, supporting the involvement of PI3K-sensitive signaling. Bidirectional manipulation of SPP1 produced reciprocal effects on xenograft growth and pulmonary colonization-related phenotypes. Serum OPN concentrations were elevated in HCC and were higher in patients with advanced-stage or metastatic disease. High OPN was associated with shorter overall survival (HR, 1.93; 95% CI, 1.01–3.69) and disease-free survival (HR, 2.29; 95% CI, 1.19–4.39).In the same cohort, the areas under the receiver operating characteristic curve for distinguishing patients with HCC from healthy controls were 0.819 for OPN, 0.781 for AFP, and 0.879 for their combination. These findings represent exploratory same-cohort discrimination and require validation in an independent, clinically representative at-risk population. Conclusion SPP1 contributes to anoikis resistance and metastatic phenotypes in HCC, and these phenotypes are sensitive to PI3K inhibition. Single-cell analyses place SPP1 within a myeloid-associated tumor microenvironment, while the inferred communication signals require further experimental validation. Circulating OPN was associated with aggressive HCC features in the present cohort, and its combination with AFP warrants exploratory evaluation in independent, clinically representative at-risk populations.

Source: Frontiers in Immunology

DOI: 10.3389/fimmu.2026.1980175

Authors: Xinyue Zhang, Honglong Wei, Reguang Pan, Qiming Ying, YanJin Dong, Mingfeng Xia