Hepatocellular carcinoma (HCC) is the global leading cause of cancer-related deaths due to the deficiency of targets for precision therapy. A new modality of epigenetic regulation has emerged involving RNA–RNA crosstalk networks where two or more competing endogenous RNAs (ceRNAs) bind to the same microRNAs. However, the contribution of such mechanisms in HCC has not been well studied. Herein, potential HMGB1-driven RNA–RNA crosstalk networks were evaluated at different HCC stages, identifying the mTORC2 component RICTOR as a potential HMGB1 ceRNA in HBV⁺ early stage HCC. Indeed, elevated HMGB1 mRNA was found to promote the expression of RICTOR mRNA through competitively binding with the miR-200 family, especially miR-429. Functional assays employing overexpression or interference strategies demonstrated that the HMGB1 and RICTOR 3′untranslated regions (UTR) epigenetically promoted the malignant proliferation, self-renewal, and tumorigenesis in HCC cells. Intriguingly, interference against HMGB1 and RICTOR in HCC cells promoted a stronger anti-PD-L1 immunotherapy response, which appeared to associate with the production of PD-L1⁺ exosomes. Mechanistically, the HMGB1-driven RNA-RNA crosstalk network facilitated HCC cell glutamine metabolism via dual mechanisms, activating a positive feedback loop involving mTORC2-AKT-C-MYC to upregulate glutamine synthetase (GS) expression, and inducing mTORC1 signaling to derepress SIRT4 on glutamate dehydrogenase (GDH). Meanwhile, this crosstalk network could impede the efficacy of immunotherapy through mTORC1-P70S6K dependent PD-L1 production and PD-L1⁺ exosomes activity. In conclusion, our study highlights the non-coding regulatory role of HMGB1 with implications for RNA-based therapeutic targeting together with a prediction of anti-PD-L1 immunotherapy in HCC.

Background: Oxidative stress has been implicated in the pathogenesis of a wide spectrum of human diseases, including Hepatitis B virus (HBV)-related liver disease. Hepatitis B virus X protein (HBx) is a key regulator of HBV that exerts pleiotropic activity on cellular functions. Recent studies showed that HBx alters mitochondrial membrane potential, thereby sensitizing cells to pro-apoptotic signals. However, it remains largely unknown whether susceptibility of hepatocytes could be disturbed by HBx under oxidative stress conditions. The purpose of this study is to determine the apoptotic susceptibility of HBx-expressing hepatocytes upon exposure to pro-oxidant stimuli in vitro and in vivo and explore its underlying mechanism. Results: Although expression of HBx itself did not activate apoptotic signaling, it significantly enhanced oxidative stress-induced cell death both in vitro and in vivo. Interestingly, this phenomenon was associated with a pronounced reduction of protein levels of Mcl-1, but not other anti-apoptotic Bcl-2 members. Importantly, enforced expression of Mcl-1 prevented HBx-triggered cell apoptosis; conversely, specific knockdown of Mcl-1 exacerbated HBx-induced apoptosis upon exposure to oxidative stress. Furthermore, inhibition of caspase-3 not only abrogated HBx-triggered apoptotic killing but also blocked HBx-induced Mcl-1 loss. Additionally, expression of HBx and Mcl-1 was found to be inversely correlated in HBV-related hepatocellular carcinogenesis (HCC) tissues. Conclusions: Our findings indicate that HBx exerts pro-apoptotic effect upon exposure to oxidative stress probably through accelerating the loss of Mcl-1 protein via caspase-3 cascade, which may shed a new light on the molecular mechanism of HBV-related hepatocarcinogenesis.

Despite the revolutionary progress in cancer immunotherapy, only a minority of hepatocellular carcinoma (HCC) patients respond to immune checkpoint inhibitors (ICIs). In this study, we found that the oncogenic circular RNA Circ-CDYL in HCC influences the efficacy of immunotherapy and the stemness characteristics of HCC cells by interacting with the hornerin (HRNR) protein. The degraded anti-PD-L1 immunotherapy responses induced by Circ-CDYL and HRNR were confirmed by peripheral blood mononuclear cells (PBMCs) killing assays in HCC cells, patient-derived organoids, and humanized immune system mouse models. Furthermore, Circ-CDYL interference reversed the cytotoxicity and proliferation of CD8⁺ T cells, resulting in ameliorated immune evasion in tumor spheroids upon anti-PD-L1 treatment. Mechanistically, Circ-CDYL upregulated HRNR expression by stabilizing the HRNR protein through the prevention of its degradation by the E3 ubiquitin ligase synoviolin 1 (SYVN1), which in sequence promoted the phosphorylation of the mTORC1 and p70S6K substrate. The abnormally activated mTORC1-p70S6K signaling increases the stemness of HCC cells and upregulates PD-L1 expression, which may attenuate anti-PD-L1 therapy efficacy via PD-L1⁺ exosomes. Our study revealed the mechanism by which Circ-CDYL and HRNR regulate the sensitivity of HCC to anti-PD-L1 therapy, and the findings have potential implications for patient stratification and clinical decision-making in HCC immunotherapy.

This study elucidated the relationships between various clinicopathologic factors and the outcome of patients with gallbladder cancer (GBC) treated by surgical resection with curative intent. Between January 2003 and January 2011, 76 patients with GBC underwent surgical resection with curative intent at our department. We then conducted a retrospective analysis of clinicopathologic data. Fourteen clinicopathological variables were selected for univariate and multivariate analysis to evaluate their influence on the outcome. The actuarial 1-, 3-, and 5-year survival rates in the 76 resected cases were 56.6%, 32.7%, and 23.8%, respectively. The univariate analysis revealed that curative resection (P<0.001), lymph node metastasis (P<0.001), AJCC stage (P = 0.030), tumor location (P = 0.008), histologic differentiation (P = 0.028), intraoperative blood loss (P = 0.011), and preoperative jaundice (P = 0.012) were significant risk factors for survival. Multivariate analysis revealed that noncurative resection and tumor location on gallbladder neck were significant risk factors for poor outcome. Among jaundiced patients, we discovered that gallbladder carcinoma with tumor thrombus in common bile duct (CBD) was very rare but with relatively special clinical manifestation and characteristic radiography manifestation. The prognosis of gallbladder carcinoma with tumor thrombus in CBD after surgical procedure was apparently better than gallbladder carcinoma with invasion of hilar tissues. Curative surgical resection remains the only effective approach to the treatment of GBC. This series confirm that jaundice is a poor prognostic factor. However, the presence of jaundice does not preclude resection, especially in highly selected patients (when R0 resection is achievable). Gallbladder carcinoma with tumor thrombus in CBD has special clinical characteristics, which need to be awared by radiologists and clinicians.

In the context of diabetes, obesity, and metabolic syndrome, the inflammatory signaling has critical roles in the pathogenesis of nonalcoholic fatty liver disease (NAFLD), but the underlying mechanisms remain poorly delineated. Herein, early and persistently elevated, proinflammatory cytokine HMGB1 expression was detected in a high‐fat diet (HFD)‐induced NAFLD model in C57BL/6 mice. The expression and extracellular release of HMGB1 was rapidly and dramatically induced by saturated palmitic acid in vitro. HFD‐induced inflammatory response and liver function impairment were both mitigated after the inhibition of endogenous HMGB1 by neutralizing antibody in vivo. The up‐regulation of HMGB1 was thought to be modified by dual channels: in the transcriptional level, it was regulated by JNK1/JNK2‐ATF2 axis; post‐transcriptionally, it was regulated by the microRNA (miR)‐200 family, especially miR‐429. miR‐429 liver conditional knockout mice (miR‐429 ^μhep ), fed either a normal diet or an HFD, showed severe liver inflammation and dysfunction, accompanied by greater expression of HMGB1. Intriguingly, the up‐regulation and release of HMGB1 could in turn self‐activate TLR4–JNK1/JNK2–ATF2 signaling, thus forming a positive feedback. Our findings reveal a novel mechanism by which HMGB1 expression was regulated by both the JNK1/2–ATF2 axis and the miR‐200 family, which provides a potential new approach for the treatment of NAFLD.—Chen, X., Ling, Y., Wei, Y., Tang, J., Ren, Y., Zhang, B., Jiang, F., Li, H., Wang, R., Wen, W., Lv, G., Wu, M., Chen, L., Li, L., Wang, H. Dual regulation of HMGB1 by combined JNK1/2–ATF2 axis with miR‐200 family in nonalcoholic steatohepatitis in mice. FASEB J. 32, 2722–2734 (2018). www.fasebj.org