Hidden Immune Signal RSAD2 May Drive Endometrial Cancer Growth, Study Finds

A large integrative study of endometrial cancer has identified an unexpected molecular player in the disease’s progression: RSAD2, an antiviral defense protein long considered a bystander of inflammation, appears to act as a bridge between tumor cells and the macrophages that crowd the tumor microenvironment. The research, published in the Journal of Translational Medicine, combines bulk multi-omics data from The Cancer Genome Atlas with laboratory experiments, single-cell sequencing, and a retrospective clinical cohort of 254 patients to build a case that RSAD2-associated CXCL1–CXCR1/2 signaling may help tumors recruit and reprogram macrophages, with consequences for patient survival.

Endometrial cancer is one of the most common gynecologic malignancies, and while immune checkpoint inhibitors have changed the treatment landscape for some patients, responses remain unpredictable. The central problem, the authors note, is heterogeneity: tumors differ widely in their immune landscapes, and validated biomarkers that connect a tumor’s intrinsic biology to its surrounding immune environment are still scarce. The team, led by Genyi Jiang and corresponding author Bilan Li of the Shanghai First Maternity and Infant Hospital, Tongji University School of Medicine, set out to close that gap by mining multi-omics data for immune-related prognostic factors.

The computational backbone of the study was an integrative analysis of the TCGA-UCEC cohort, the largest public genomic dataset for endometrial carcinoma. Rather than examining messenger RNA in isolation, the researchers constructed a multi-omics framework that coupled hub genes with transcription factor associations, microRNA regulation, DNA methylation sites, and somatic mutation features across candidate modules, including a black module containing DDX58 and RSAD2 and additional blue, brown, and red modules enriched for immune signaling genes such as CD8A, CXCR3, CD74, and HLA-A. The resulting multi-omics score stratified patients by survival and by distinct immune features, and RSAD2 emerged as a molecule whose high expression tracked with adverse survival and with macrophage-related immune signatures.

RSAD2, short for Radical S-adenosyl methionine domain-containing protein 2, is an interferon-stimulated gene, meaning its expression surges when cells detect viral infection or inflammatory signals. That lineage gave the team a plausible mechanistic question: could an antiviral protein, chronically activated within the tumor, be doing more than reflecting inflammation? To find out, the researchers turned to gain- and loss-of-function experiments in endometrial cancer cell lines, forcing RSAD2 expression upward in some cells and silencing it with short hairpin RNAs in others.

The results were consistent across multiple assays. Overexpression of RSAD2 enhanced cancer cell proliferation, migration, and invasion, and increased both colony formation in two-dimensional culture and sphere formation in three-dimensional culture, a proxy for stem-like tumor behavior. In a xenograft mouse model, tumors engineered to overproduce RSAD2 grew faster. Knocking the gene down produced the opposite effects: reduced EdU staining for proliferation, fewer cells crossing Transwell membranes in migration and invasion assays, smaller and fewer spheroids, and lower viability in CCK-8 assays measured over time. Together, these experiments positioned RSAD2 not as a passive marker but as a functional driver of malignant phenotypes in vitro and in vivo.

To trace how RSAD2 exerts these effects, the team performed bulk RNA sequencing after RSAD2 knockdown and analyzed the differentially expressed genes through Gene Ontology and KEGG pathway frameworks. The transcriptomic signature pointed toward activation of the RAF–MEK–ERK cascade, a core arm of the MAPK signaling pathway that governs cell growth and survival. Western blotting confirmed the biochemical readout: the ratios of phosphorylated RAF1, MEK1/2, and ERK1/2 to their total protein levels shifted in concordance with RSAD2 expression, and the downstream immune-checkpoint protein PD-L1 moved in parallel, rising with RSAD2 overexpression and falling with knockdown. Among the upregulated genes was CXCL1, a chemokine known to signal through the CXCR1 and CXCR2 receptors expressed on myeloid cells.

The chemokine connection proved central. Quantitative RT-PCR and ELISA assays showed that CXCL1 expression and secretion changed in step with RSAD2 levels, and that this coupling was preserved under inflammatory stimulation. Single-cell RNA sequencing of integrated public datasets spanning normal endometrium, atypical endometrial hyperplasia, and endometrioid endometrial carcinoma placed RSAD2 expression in context alongside myeloid markers such as ITGAM and AIF1, hinting at a spatial relationship between RSAD2-high epithelial cells and myeloid populations as tissue progresses toward malignancy.

The functional test of tumor–macrophage communication followed a logic of conditioned media and co-culture. When the researchers exposed THP-1-derived macrophages to conditioned medium from RSAD2-overexpressing endometrial cancer cells, the macrophages showed enhanced chemotaxis, migrating more vigorously toward the tumor-derived signal, and mounted a mixed activation-associated transcriptional response. Critically, adding SX-517, an inhibitor of the CXCR1/2 receptors, attenuated both the migration and the transcriptional shift, implicating the CXCL1–CXCR1/2 axis as the conduit through which RSAD2-high tumors communicate with macrophages. In many solid tumors, tumor-associated macrophages occupy a spectrum between anti-tumor inflammatory states and pro-tumor states that suppress immunity and remodel tissue; a chemokine-driven recruitment program that tilts that balance would fit the adverse survival signal seen in the clinical data.

The translational dimension came from a retrospective cohort of 254 endometrial cancer patients treated at the authors’ institution, with ethics approval from the Shanghai First Maternity and Infant Hospital institutional review board and informed consent from all participants. Immunohistochemistry and multiplex immunohistochemistry on tumor sections showed that RSAD2 expression was elevated in endometrial cancer tissue compared with controls, correlated with immune-cell infiltration, and associated with poorer survival outcomes in univariable analyses. The clinical staining thus closed the loop that the TCGA analysis had opened: the same molecule flagged computationally as a risk factor could be visualized in patient tissue, colocalized with immune populations, and tied to outcome.

The authors are careful about scope. Their conclusion frames RSAD2 as a candidate biomarker of endometrial cancer progression and supports a potential role for RSAD2-associated CXCL1–CXCR1/2 signaling in tumor–macrophage communication, while explicitly stating that further ligand-specific, genetic, and immune-competent validation is required to establish mechanistic and translational significance. The experiments relied in part on immortalized cell lines and a THP-1 macrophage model, and the xenograft system lacks a fully intact immune system, so the immunology of the axis remains to be proven in immune-competent settings. Whether CXCR1/2 inhibition could complement existing immunotherapies in endometrial cancer is an obvious next question, as is whether RSAD2’s interferon-driven expression reflects chronic viral mimicry or another inflammatory trigger within the tumor microenvironment. What the study delivers now is a well-supported hypothesis with a molecular address: a biomarker linking a tumor’s intrinsic inflammatory state to the macrophages that surround it, and a signaling axis that drug developers have already learned to inhibit.

Subject of Research: RSAD2-associated CXCL1–CXCR1/2 signaling in tumor–macrophage communication and endometrial cancer progression

Article Title: Integrative multi-omics analysis implicates RSAD2-associated CXCL1–CXCR1/2 signaling in tumor–macrophage communication and progression of endometrial cancer

Article References: Jiang, G., Zhang, Y., Ding, Y., Cao, M., Kang, L., Sun, Y., Yan, J., Zhang, Y., Luo, J., Zhou, X., Wu, H., & Li, B. (2026). Integrative multi-omics analysis implicates RSAD2-associated CXCL1–CXCR1/2 signaling in tumor–macrophage communication and progression of endometrial cancer. Journal of Translational Medicine. https://doi.org/10.1186/s12967-026-09080-3

Image Credits: AI Generated

DOI: 10.1186/s12967-026-09080-3

Keywords: endometrial cancer, RSAD2, CXCL1, CXCR1/2, tumor-associated macrophages, tumor microenvironment, multi-omics, RAF-MEK-ERK, chemokine signaling, immunotherapy biomarkers, TCGA-UCEC, xenograft model