Wnt5a suppresses colorectal cancer progression via TGF-β/NOTUM/OLFM4 axis in patient-derived organoids

Background: Wnt5a, a noncanonical Wnt ligand, exhibits dual roles in Cancer progression, but its tumor-suppressive mechanisms in colorectal Cancer (CRC) remain poorly defined. Stromal-derived signals in the tumor microenvironment (TME) are increasingly recognized as critical modulators of CRC behavior, yet their interplay with therapeutic resistance is unclear.

Methods: Using patient-derived CRC organoids (PDOs) and functional assays, we investigated the role of stromal-secreted Wnt5a. Mechanistic studies combined RNA Sequencing, pharmacological inhibition, and immunofluorescence to dissect the Wnt5a/TGF-β/NOTUM/OLFM4 axis. Drug sensitivity assays evaluated the synergy between Wnt5a and 5-fluorouracil (5-FU).

Results: Wnt5a was predominantly stromal-derived and suppressed CRC Organoid growth by activating TGF-β/SMAD2 signaling, which upregulated the Wnt Inhibitor NOTUM and downregulated the stemness marker OLFM4. RNA-seq revealed NOTUM induction as the key mediator. Combining Wnt5a with 5-FU synergistically enhanced Organoid growth inhibition and cell death, reversing 5-FU-driven NOTUM downregulation.

Conclusions: Our study identifies a novel stromal-TME crosstalk mechanism wherein Wnt5a restrains CRC progression via TGF-β/NOTUM/OLFM4 signaling. The combinatorial efficacy of Wnt5a and 5-FU highlights a promising strategy to overcome chemoresistance. These findings emphasize the therapeutic potential of targeting stromal-derived pathways in CRC.

Chemosensitization; Colorectal cancer progression; NOTUM; Wnt5a.