Radic-Sarikas, B. | Search bioRxiv

bioRxiv2026

A human lung organoid co-culture model of early bone sarcoma metastasis reveals contact-dependent epithelial remodeling at the metastatic interface

Lung metastasis drives mortality across cancer types, yet how infiltrating tumor cells remodel the lung epithelium to establish metastatic niches remains poorly understood. Here we establish MESCUL (MEtastatic Sarcoma Co-CULture), a co-culture platform combining human lung organoids with patient-derived bone sarcoma cells to model early tumor-lung epithelial interactions in a physiologically relevant 3D system. MESCUL reveals that direct tumor-epithelial contact induces rapid, reproducible lung epithelial remodeling across Ewing sarcoma (ES) and osteosarcoma (OS) models and multiple organoid donor backgrounds, which is contact-dependent and not recapitulated by paracrine signaling. Single-cell RNA sequencing identifies LIMES (Lung Interface Metastasis Signature), a shared transcriptional program encompassing focal adhesion assembly, matrix metalloprotease (MMP) upregulation, and emergence of a damage-associated transitional cell state, in both ES and OS. Mechanistically, tumor-derived fibronectin (FN1) engages epithelial integrin receptors to activate focal adhesion kinase (FAK), driving amphiregulin (AREG) induction and MMP-mediated remodeling; FN1 alone phenocopies this response, and FAK inhibition attenuates it, nominating the FN1-integrin-FAK-AREG axis as a candidate therapeutic vulnerability. The LIMES program, identified through the MESCUL co-culture model, is spatially confined to the tumor-lung interface in patient metastases of both ES and OS, as demonstrated by spatial transcriptomics across nine patients. Massons trichrome staining of matched patient sections reveals pronounced collagen deposition in the peri-tumoral lung parenchyma, consistent with LIMES acting upstream of a wound-healing cascade that proceeds to structural fibrotic remodeling in patient tissue. Together, these findings establish the lung epithelium as an active participant in metastatic colonization, characterize a pharmacologically targetable, spatially restricted epithelial remodeling response at the bone sarcoma-lung interface across OS and ES, and introduce MESCUL as a tractable 3D platform for investigating lung metastasis, with possible implications for tumor types beyond bone sarcomas.

cancer biology↗

bioRxiv2025

Mevalonate pathway activation in Ewing sarcoma reveals a 3D-specific synergy between statins and BCL-xL inhibition

Bone sarcomas are rare and aggressive pediatric cancers with limited progress in targeted therapy development, in part due to the poor physiological relevance of conventional two-dimensional (2D) culture systems used for preclinical testing. To address this gap, we developed a standardized three-dimensional (3D) culture and drug-testing platform for Ewing sarcoma (ES) and osteosarcoma (OS) that more accurately recapitulates in vivo tumor biology. Across 3D spheroids, bioprinted constructs, and patient-derived xenograft (PDX) cultures, we observed a consistent activation and dependency on the mevalonate pathway in ES. Leveraging this platform, we identified a selective therapeutic synergy between statins, which inhibit mevalonate pathway flux, and BCL-xL inhibitors, a vulnerability that was not detectable in 2D cultures. These findings highlight the mevalonate pathway as a targetable metabolic dependency in ES and demonstrate how physiologically grounded 3D models can uncover clinically actionable treatment strategies that remain hidden in traditional 2D systems. Our findings show that 3D tumor models can expose actionable metabolic vulnerabilities obscured by traditional approaches, supporting their use in rational combination therapy discovery for aggressive pediatric sarcomas.

cancer biology↗