HMMR triggers immune evasion of hepatocellular carcinoma by inactivation of phagocyte killing.

Wu, Hong; Liu, Yiqiang; Liu, Qianshi; Li, Zhaoshen; Wan, Yejian; Cao, Chenhui; Wu, Binghuo; Liu, MingXin et al. · Sci Adv · 2024

basic_science · Level V

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Abstract

Hepatocellular carcinoma (HCC) acquires an immunosuppressive microenvironment, leading to unbeneficial therapeutic outcomes. Hyaluronan-mediated motility receptor (HMMR) plays a crucial role in tumor progression. Here, we found that aberrant expression of HMMR could be a predictive biomarker for the immune suppressive microenvironment of HCC, but the mechanism remains unclear. We established an HMMR<sup>-/-</sup> liver cancer mouse model to elucidate the HMMR-mediated mechanism of the dysregulated "don't eat me" signal. HMMR knockout inhibited liver cancer growth and induced phagocytosis. HMMR<sup>high</sup> liver cancer cells escaped from phagocytosis via sustaining CD47 signaling. Patients with HMMR<sup>high</sup>CD47<sup>high</sup> expression showed a worse prognosis than those with HMMR<sup>low</sup>CD47<sup>low</sup> expression. HMMR formed a complex with FAK/SRC in the cytoplasm to activate NF-κB signaling, which could be independent of membrane interaction with CD44. Notably, targeting HMMR could enhance anti-PD-1 treatment efficiency by recruiting CD8<sup>+</sup> T cells. Overall, our data revealed a regulatory mechanism of the "don't eat me" signal and knockdown of HMMR for enhancing anti-PD-1 treatment.

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