Immune checkpoint therapy-elicited sialylation of IgG antibodies impairs antitumorigenic type I interferon responses in hepatocellular carcinoma.

The reinvigoration of anti-tumor T cells in response to immune checkpoint blockade (ICB) therapy is well established. Whether and how ICB therapy manipulates antibody-mediated immune response in cancer environments, however, remains elusive. Using tandem mass spectrometric analysis of modification of immunoglobulin G (IgG) from hepatoma tissues, we identified a role of ICB therapy in catalyzing IgG sialylation in the Fc region. Effector T cells triggered sialylation of IgG via an interferon (IFN)-γ-ST6Gal-I-dependent pathway. DC-SIGN+ macrophages represented the main target cells of sialylated IgG. Upon interacting with sialylated IgG, DC-SIGN stimulated Raf-1-elicited elevation of ATF3, which inactivated cGAS-STING pathway and eliminated subsequent type-I-IFN-triggered antitumorigenic immunity. Although enhanced IgG sialylation in tumors predicted improved therapeutic outcomes for patients receiving ICB therapy, impeding IgG sialylation augmented antitumorigenic T cell immunity after ICB therapy. Thus, targeting antibody-based negative feedback action of ICB therapy has potential for improving efficacy of cancer immunotherapies.

Targeting inflammatory macrophages rebuilds therapeutic efficacy of DOT1L inhibition in hepatocellular carcinoma.

Epigenetic reprogramming is a promising therapeutic strategy for aggressive cancers, but its limitations in vivo remain unclear. Here, we showed, in detailed studies of data regarding 410 patients with human hepatocellular carcinoma (HCC), that increased histone methyltransferase DOT1L triggered epithelial-mesenchymal transition-mediated metastasis and served as a therapeutic target for human HCC. Unexpectedly, although targeting DOT1L in vitro abrogated the invasive potential of hepatoma cells, abrogation of DOT1L signals hardly affected the metastasis of hepatoma in vivo. Macrophages, which constitute the major cellular component of the stroma, abrogated the anti-metastatic effect of DOT1L targeting. Mechanistically, NF-κB signal elicited by macrophage inflammatory response operated via a non-epigenetic machinery to eliminate the therapeutic efficacy of DOT1L targeting. Importantly, therapeutic strategy combining DOT1L-targeted therapy with macrophage depletion or NF-κB inhibition in vivo effectively and successfully elicited cancer regression. Moreover, we found that the densities of macrophages in HCC determined malignant cell DOT1L-associated clinical outcome of the patients. Our results provide insight into the crosstalk between epigenetic reprogramming and cancer microenvironments and suggest that strategies to influence the functional activities of inflammatory cells may benefit epigenetic reprogramming therapy.

Targeting Ferroptosis-Elicited Inflammation Suppresses Hepatocellular Carcinoma Metastasis and Enhances Sorafenib Efficacy.

Triggering ferroptosis, an iron-dependent form of cell death, has recently emerged as an approach for treating cancer. A better understanding of the role and regulation of ferroptosis is needed to realize the potential of this therapeutic strategy. Here, we observed extensive activation of ferroptosis in hepatoma cells and human hepatocellular carcinoma (HCC) cases. Patients with low to moderate activation of ferroptosis in tumors had the highest risk of recurrence compared to patients with no or high ferroptosis. Upon encountering ferroptotic liver cancer cells, aggregated macrophages efficiently secreted proinflammatory IL1ß to trigger neutrophil-mediated sinusoidal vascular remodeling, thereby creating favorable conditions for aggressive tumor growth and lung metastasis. Mechanistically, hyaluronan fragments released by cancer cells acted via an NF-κB-dependent pathway to upregulate IL1ß precursors and the NLRP3 inflammasome in macrophages, and oxidized phospholipids secreted by ferroptotic cells activated the NLRP3 inflammasome to release functional IL1ß. Depleting either macrophages or neutrophils or neutralizing IL1ß in vivo effectively abrogated ferroptosis-mediated liver cancer growth and lung metastasis. More importantly, the ferroptosis-elicited inflammatory cellular network served as a negative feedback mechanism that led to therapeutic resistance to sorafenib in HCC. Targeting the ferroptosis-induced inflammatory axis significantly improved the therapeutic efficacy of sorafenib in vivo. Together, this study identified a role for ferroptosis in promoting HCC by triggering a macrophage/IL1ß/neutrophil/vasculature axis. SIGNIFICANCE: Ferroptosis induces a favorable tumor microenvironment and supports liver cancer progression by stimulating an inflammatory cellular network that can be targeted to suppress metastasis and improve the efficacy of sorafenib.