Epithelial-mesenchymal transition (EMT) is a critical process for tumor invasion and metastasis. Hypoxia may induce EMT, and upregulated β-catenin expression has been found in various tumors. In this study, we investigate the role of β-catenin in hypoxia-induced EMT in hepatocellular carcinoma (HCC). Induction of EMT in HCC cell lines by hypoxia was confirmed by altered morphology, expression change of EMT-associated markers and enhanced invasion capacity. We showed that hypoxia-induced EMT could be enhanced by addition of recombinant Wnt3a while it was repressed by β-catenin small interfering RNA. An interaction between β-catenin and hypoxia-induced factor-1α (hif-1α) was found, and an underlying competition for β-catenin between hif-1α and T-cell factor-4 was implied. Notably, increased hif-1α activity was accompanied with more significant EMT features. We also showed that the pro-EMT effect of β-catenin in hypoxia was deprived in the absence of hif-1α. Moreover, β-catenin was found to be responsible for the maintenance of viability and proliferation for tumor cells undergoing hypoxia. We further showed a correlation between hif-1α and β-catenin expression, and corresponding expression of EMT-associated markers in human HCC tissues. Our results suggest that Wnt/β-catenin signaling enhances hypoxia-induced EMT in HCC by increasing the EMT-associated activity of hif-1α and preventing tumor cell death.

Doxorubicin is conventionally used in chemotherapy against hepatocellular carcinoma (HCC), but acquired resistance developed during long-term therapy limits its benefits. Autophagy, a conserved catabolic process for cellular self-protection and adaptation to the changing environment, is regarded as a potential clinical target to overcome doxorubicin resistance. In this study, the potential role of miR-223 in modulating doxorubicin-induced autophagy and sensitivity were evaluated in four transfected human HCC cell lines, and the in vivo relevance was assessed using a mouse xenograft model of HCC. We found that the well-defined miR-223 is expressed at low levels in doxorubicin treated HCC cells and that miR-223 overexpression inhibits the doxorubicin-induced autophagy that contributes to chemoresistance. Blockade of autophagic flux by chloroquine resulted in the failure of miR-223 inhibitor to suppress doxorubicin sensitivity of HCC cells. We further identified FOXO3a as a direct downstream target of miR-223 and primary mediator of the regulatory effect of miR-223 on doxorubicin-induced autophagy and chemoresistance in HCC cells. Finally, we confirmed the enhancement of doxorubicin sensitivity by agomiR-223 in xenograft models of HCC. These findings establish a novel miRNA-based approach for autophagy interference to reverse doxorubicin resistance in future chemotherapy regimens against human HCC.

Clinical immunotherapy of solid tumors elicits durable responses only in a minority of patients, largely due to the highly immunosuppressive tumor microenvironment (TME). Although rational combinations of vaccine adjuvants with inflammatory cytokines or immune agonists that relieve immunosuppression represent an appealing therapeutic strategy against solid tumors, there are unavoidable nonspecific toxicities due to the pleiotropy of cytokines and undesired activation of off‐target cells. Herein, a Zn2+ doped layered double hydroxide (Zn‐LDH) based immunomodulating adjuvant, which not only relieves immunosuppression but also elicits robust antitumor immunity, is reported. Peritumorally injected Zn‐LDH sustainably neutralizes acidic TME and releases abundant Zn2+, promoting a pro‐inflammatory network composed of M1‐tumor‐associated macrophages, cytotoxic T cells, and natural‐killer cells. Moreover, the Zn‐LDH internalized by tumor cells effectively disrupts endo‐/lysosomes to block autophagy and induces mitochondrial damage, and the released Zn2+ activates the cGas‐STING signaling pathway to induce immunogenic cell death, which further promotes the release of tumor‐associated antigens to induce antigen‐specific cytotoxic T lymphocytes. Unprecedentedly, merely injection of Zn‐LDH adjuvant, without using any cytotoxic inflammatory cytokines or immune agonists, significantly inhibits the growth, recurrence, and metastasis of solid tumors in mice. This study provides a rational bottom‐up design of potent adjuvant for cancer metalloimmunotherapy against solid tumors.

Acquired resistance to chemotherapy is a major obstacle in breast cancer (BC) treatment. Accumulated evidence has uncovered that microRNAs (miRNAs) are vital regulators of chemoresistance in cancer. Growing studies reveal that miR-137 acts as a suppressor in tumor progression. However, it remains obscure the role of miR-137 in modulating the sensitivity of BC cells to doxorubicin (DOX). In this study, we demonstrate that miR-137 exerts a significant effect on repressing the development of chemoresistance of BC cells in response to DOX via attenuating epithelialmesenchymal transition (EMT) of tumor cells in vitro and in vivo. MiR-137 overexpression dramatically elevated the sensitivity of BC cells to DOX as well as impaired the DOX-promoted EMT of tumor cells. Mechanistically, miR-137 directly targeted dual-specificity phosphatase 4 (DUSP4) to impact on the EMT and chemoresistance of BC cells upon DOX treatment. Consistently, decreased DUSP4 efficiently enhanced the sensitivity of BC cells to DOX while overexpressed DUSP4 significantly diminished the beneficial effect of miR-137 on BC cells chemoresistance. Moreover, the increased miR-137 heightened the sensitivity of BC cells-derived tumors to DOX through targeting DUSP4 in vivo. Together, our results provide a novel insight into the DOX resistance of BC cells and miR-137 may serve as a new promising therapeutic target for overcoming chemoresistance in BC.

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