HERC1 oncogene enhances stemness and tumorigenic potential in CD44+-derived organoids of head and neck squamous cell carcinoma through IL-6/STAT3 signaling

Abstract HECT and RCC1-like domain-containing protein 1 (HERC1), a large E3 ubiquitin ligase, has been implicated in neural development and genome stability, but its role in cancer remains unclear. This study identifies HERC1 as a critical regulator of cancer stemness, metastasis, and chemoresistance in head and neck squamous cell carcinoma (HNSCC). CD44⁺ HNSCC organoids with shRNA-mediated HERC1 knockdown were assessed for stemness, EMT, and IL-6/STAT3/HERC1 signaling using molecular assays, CAF co-culture, xenografts, and tissue immunohistochemistry. High HERC1 expression in TCGA-HNSCC datasets was associated with enrichment of stemness signatures. HERC1 knockdown in CD44⁺ cells reduced Sox2, and Slug expression, suppressed EMT, and impaired metastatic potential in Transwell assays and in vivo models. CD44⁺ cells formed organoids in a HERC1-dependent manner. CAF co-culture showed that IL-6 promoted organoid invasiveness through STAT3 activation and HERC1 upregulation. Mechanistic validation revealed that HERC1 modulation altered p-STAT3, p-ERK, CD44, and Slug levels, and STAT3 inhibition reduced HERC1 expression, defining a p-STAT3–HERC1–p-ERK axis. IL-6 neutralization or HERC1 inhibition sensitized organoids to 5-fluorouracil and cisplatin, and combined HERC1 knockdown with 5-FU markedly reduced tumor growth and increased apoptosis. Tissue arrays confirmed elevated HERC1 and pathway markers in advanced HNSCC. These findings define an p-STAT3–HERC1–p-ERK signaling axis that promotes cancer stemness and chemoresistance through CD44 + tumor–stromal crosstalk. Targeting HERC1 may offer a promising strategy to eliminate cancer stem-like cells in HNSCC.