INHBA expression enriched in α-SMA+ fibroblast-like cells is associated with COAD cell growth and 5-FU resistance with concomitant impairment of necroptosis-related signaling and antitumor immunity

Abstract Objectives Inhibin subunit beta A (INHBA), a member of the transforming growth factor-β (TGF-β) superfamily, has been implicated in tumor progression, but its cellular origin, functional roles, and underlying mechanisms in colon adenocarcinoma (COAD) remain largely unknown. This study aimed to explore the expression pattern, biological functions, and immunoregulatory effects of INHBA in COAD. Methods Bioinformatic analyses were performed using the TCGA-COAD dataset and the single-cell RNA sequencing dataset. Flow cytometry was applied to validate the INHBA level in cancer-associated fibroblasts (CAFs) from COAD and paired adjacent normal tissues. Two patient-derived organoids (PDOs) were established to evaluate the effects of recombinant INHBA protein and INHBA-neutralizing antibody on tumor growth and 5-FU sensitivity. Ex vivo tumor-immune co-culture was constructed to investigate the impact of INHBA on T cell phenotypes and dendritic cell (DC) maturation. Results INHBA was significantly upregulated in COAD tissues and associated with inflammatory signaling pathways. Single-cell transcriptomic analysis and clinical sample validation revealed that INHBA was predominantly produced by the α-SMA+ fibroblast subpopulation in COAD. Functional assays showed that recombinant INHBA promoted tumor growth and chemoresistance, whereas an INHBA-neutralizing antibody exerted opposite effects. INHBA neutralization was associated with increased necroptosis signaling and DAMPs (Damage-Associated Molecular Patterns) release, whereas it did not significantly affect apoptosis. In co-culture, INHBA neutralization was associated with increased proportions of CD8+ T cells, a higher proportion of Granzyme B+ cells among CD8+ T cells, and altered DC maturation markers. Conclusions INHBA expression in α-SMA+ fibroblast-like cells is associated with COAD progression and chemoresistance and occurred alongside suppressed tumor cell necroptosis and attenuated antitumor immunity.