Abstract <p>Esophageal squamous cell carcinoma (ESCC) is a common and aggressive subtype of esophageal cancer. This research investigates the functions of cancer-associated fibroblasts (CAFs) in the malignant phenotype of ESCC and probes the underpinning mechanism. Key CAF-associated proteins in ESCC were identified using bioinformatics analyses. ESCC cell lines were co-cultured with CAFs, followed by the addition of neutralizing antibodies against WNT family member 5A (WNT5A) (Anti-WNT5A; AW) and frizzled class receptor 5 (FZD5) (Anti-FZD5; AF), or a human recombinant protein of WNT5A (rWNT5A; rW). The effects of CAF stimulation and the neutralizing or recombinant proteins on the growth and dissemination of ESCC cells were investigated. In addition, ESCC cells were transplanted into nude mice for in vivo assessment of tumor growth and metastasis. WNT5A was identified as a CAF-associated protein linked to poor prognosis in ESCC. Co-culturing with CAFs augmented proliferation, mobility, and apoptosis resistance of ESCC cells. These effects were negated by the AW or AF but restored by rW. WNT5A interacted with FZD5 to activate the WNT signaling in ESCC cells. The rW treatment also enhanced tumorigenesis and metastasis of xenograft tumors in nude mice, with these effects diminished by AW or AF treatment. This study suggests that CAFs promote growth and dissemination of ESCC cell primarily through the secretion of WNT5A.</p> Graphical abstract <p></p>