Altered metabolism is one of the hallmarks of cancer cells. Pentose phosphate pathway (PPP) is a fundamental component of cellular metabolism. Glucose-6-phosphate dehydrogenase (G6PD), the rate-limiting enzyme of the PPP, is elevated in many cancers and contributes to tumor growth by producing ribose-5-phosphate and NADPH through PPP. However, the role of G6PD in hepatocellular carcinoma (HCC) metastasis and the clinical significance of G6PD in HCC progression and prognosis have not been well determined. In this study, by investigating tissue samples from HCC patients and HCC cell lines, we found that elevated G6PD expression is significantly associated with HCC metastasis and poor prognosis of HCCs, and that knockdown of G6PD inhibits in vitro proliferation, migration and invasion of HCC cell lines. Further studies reveal that G6PD contributes to HCC migration and invasion of hepatocellular carcinoma cells by inducing epithelial-mesenchymal transition through activation of signal transducer and activator of transcription 3 (STAT3) pathway. Our findings suggest that targeting G6PD could open up possibilities for metastasis intervention and improve the patients’ outcomes for HCC.

Background: Agents targeting the programmed death ligand 1 (PD-L1)/programmed death receptor 1 immune checkpoint exhibited promising clinical outcomes in a variety of malignant tumors, including intrahepatic cholangiocarcinoma (ICC). However, the relationship between PD-L1 expression and CD8⁺ T-cell immune responses is not well defined in ICC. Patients and methods: We investigated PD-L1 expression immunohistochemistry in formalin-fixed, paraffin-embedded tissues from 192 ICC patients undergoing curative resection and correlated our results with the clinicopathologic features and prognosis. We also quantified CD8⁺ T-cell infiltration in ICC specimens and evaluated the relationship between PD-L1 expression and CD8⁺ T-cell infiltration. After incubating human ICC cell lines (HCCC9810 and RBE) with interferon (IFN)-γ, we measured the PD-L1 expression of these ICC cells by Western blot and flow cytometry. Results: Only 34 patients (17.7%) showed ≥5% membranous PD-L1 expression on tumor cells, and tumoral PD-L1 overexpression (≥5%) was significantly associated with superior overall survival (P=0.012) and disease-free survival (P=0.018). A significant positive association was found between PD-L1 expression and the presence of CD8⁺ T-cells. In fresh frozen ICC specimens, IFN-γ was found to be significantly correlated with PD-L1 and CD8A gene expression, as evaluated by reverse transcription-polymerase chain reaction. Moreover, stimulation of the HCCC9810 and RBE cells with recombinant IFN-γ, secreted by CD8⁺ T-cells rapidly induced PD-L1 upregulation in these cell lines in vitro. Conclusion: Tumor PD-L1 overexpression is mainly stimulated by activated CD8⁺ T-cells pre-existing in the ICC microenvironment, and PD-L1 is a favorable prognostic factor for the patients. These observations suggest that anti-PD-L1/programmed death receptor 1 therapy may benefit ICC patients with tumor cell PD-L1 expression and the presence of CD8⁺ T-cells.

The epithelial‑mesenchymal transition (EMT) serves critical roles in the migration, invasion and metastasis of human cancer cells. This process is initiated by regulation of E‑cadherin expression by the major inducers of EMT. Previous studies reported that osteopontin (OPN) is essential for hepatocellular carcinoma (HCC) metastasis as it facilitates the EMT in HCC. However, the role and clinical significance of OPN as an EMT regulator in HCC remains unknown. The present study revealed that OPN regulated the expression of Twist by activating RAC serine/threonine‑protein kinase (Akt), a critical EMT regulator. Interfering with the phosphoinositide 3‑kinase (PI3K)/Akt pathway may suppress the expression of Twist enhanced by OPN. Increased Twist levels in HCC were associated with poor survival and tumor recurrence in patients with HCC following surgery. A significant association was observed between OPN expression and Twist levels in HCC, and a combination of these two parameters was revealed to be a more powerful predictor of poor patient prognosis. The findings of the present study indicate that Twist serves an notable role in OPN‑mediated metastasis of HCC through activation of the PI3K/Akt pathway. Twist may be a potential therapeutic target for the prevention of HCC metastasis in patients exhibiting high OPN expression.

Multidrug resistance is one of the reasons for low survival of advanced hepatocellular carcinoma (HCC). Our previous studies indicate that the hedgehog signalling is involved in hepatic carcinogenesis, metastasis and chemo‐resistance. The present study aims to uncover molecular mechanisms underlying hepatoma chemo‐resistance. TAP1 and GLI1/2 gene expression was assessed in both poorly differentiated hepatoma cells and HCC specimens. Potential GLI‐binding site in the TAP1 promoter sequence was validated by molecular assays. Approximately 75% HCC specimens exhibited an elevated expression of hedgehog GLI1 transcription factor compared with adjacent liver tissue. Both GLI1/2 and TAP1 protein levels were significantly elevated in poorly differentiated hepatoma cells. Both Huh‐7‐trans and Huh‐7‐DN displayed more karyotypic abnormalities and differential gene expression profiles than their native Huh‐7 cells. Sensitivity to Sorafenib, doxorubicin and cisplatin was remarkably improved after either GLI1 or TAP1 gene was inhibited by an RNAi approach or by a specific GLI1/2 inhibitor, GANT61. Further experiments confirmed that hedgehog transcription factor GLI1/2 binds to the TAP1 promoter, indicating that TAP1 is one of GLI1/2 target genes. In conclusion, TAP1 is under direct transcriptional control of the hedgehog signalling. Targeting hedgehog signalling confers a novel insight into alleviating drug resistance in the treatment of refractory HCC.

MicroRNAs play significant roles in the development of cancer and may serve as promising therapeutic targets. In our previous work, miR-219-5p was identified as one of the important metastasis-related microRNAs in HCC. Here we demonstrated that miR-219-5p expression was elevated in HCC tissues and was associated with vascular invasion and dismal prognosis. In multivariate analysis, miR-219-5p was identified as an independent prognostic indicator for HCC patients. Functional mechanism analyses showed that miR-219-5p promoted HCC cell proliferation and invasion in in vitro, as well as in vivo, tumor growth and metastasis in nude mice models bearing human HCC tumors. In addition, cadherin 1 (CDH1) was revealed to be a downstream target of miR-219-5p in HCC cells. In conclusion, miR-219-5p promotes tumor growth and metastasis of HCC by regulating CDH1 and can serve as a prognostic marker for HCC patients.

Recent evidence has highlighted immune checkpoint inhibitors as among the most promising immunotherapies for various malignancies. However, a significant proportion of HCC patients exhibit poor responses. Lipid metabolic heterogeneity is considered a key driver of cancer progression. However, the role of lipid metabolic reprogramming in HCC immunotherapy resistance remains poorly understood. Herein, we aimed to illuminate the potential relationship between lipid metabolic reprogramming and ICI resistance and provide novel strategies to increase the HCC immunotherapy response. Patients who received PD-1/PD-L1 inhibitors were enrolled. The effect of TACC3 on the tumor microenvironment was validated via single-cell RNA sequencing in HCC-bearing mouse models. Targeted metabolomics was performed to analyze the regulatory role of TACC3 in HCC metabolism. To address HCC immunotherapy resistance, we developed a targeted nucleic acid therapeutic utilizing N-acetylgalactosamine (GalNAc) to conjugate siTACC3. Through clinical cohort analysis, we found that TACC3 was overexpressed in HCC patients with poor response to immunotherapy. Furthermore, we demonstrated that silencing tumor-derived TACC3 optimizes the cytotoxicity of infiltrating CD8⁺ T lymphocytes. Both in vitro and in vivo assays suggested that TACC3 maintains ACSL4-mediated polyunsaturated fatty acid (PUFA) metabolism in HCC cells. Additionally, TACC3 accelerates ACSL4 expression by interacting with LARP1 and PABPC1, which stabilize ACSL4 mRNA. The results of preclinical models demonstrated the satisfactory efficacy of GalNAc-conjugated siTACC3 combined with PD-1 inhibitor therapy for HCC. In summary, tumor-derived TACC3 impairs the tumor-killing activity of CD8⁺ T lymphocytes through PUFA metabolism-associated crosstalk. Targeting TACC3 represents a novel and practicable strategy to augment ICI efficacy against HCC.