Culture-dependent baseline states and drug response programs in myxofibrosarcoma models across 2D and 3D systems.

Myxofibrosarcoma (MFS) is a rare soft-tissue sarcoma with limited systemic therapy options, necessitating preclinical platforms that better simulate clinical drug responses. We investigated how 2D monolayers versus 3D spheroids shape the baseline transcriptome and doxorubicin (DOX)-responsive programs across six patient-derived MFS cell lines. RNA sequencing revealed that 3D culture induces a distinct transcriptomic state characterized by the enrichment of microenvironment-associated stress programs, such as hypoxia, inflammatory/NF-κB signaling, and glycolysis, alongside the suppression of proliferation-related pathways. Although the global DOX-induced transcriptional response was highly environment-dependent, we identified a robust core of six regulators-MCRIP1, FGF12, HGF, EMSY, FZD2, and SECISBP2-whose transcriptional changes consistently correlated with cell survival rates across both 2D and 3D geometries. These genes are involved in transcriptional plasticity, redox homeostasis, and bypass survival signaling, providing a mechanistic basis for DOX resistance that transcends culture conditions. Our findings demonstrate that while culture geometry is a critical determinant of the MFS transcriptome, a robust set of environment-agnostic regulators dictates DOX efficacy. Integrating 3D systems with these specific transcriptomic readouts enhances the interpretability of drug screenings and supports the prioritization of rational therapeutic combinations for this rare sarcoma.