Identification of Fasudil as a collaborator to promote the anti-tumor effect of lenvatinib in hepatocellular carcinoma by inhibiting GLI2-mediated hedgehog signaling pathway.

Lenvatinib is a frontline tyrosine kinase inhibitor for patients with advanced hepatocellular carcinoma (HCC). However, just 25% of patients benefit from the treatment, and acquired resistance always develops. To date, there are neither effective medications to combat lenvatinib resistance nor accurate markers that might predict how well a patient would respond to the lenvatinib treatment. Thus, novel strategies to recognize and deal with lenvatinib resistance are desperately needed. In the current study, a robust Lenvatinib Resistance index (LRi) model to predict lenvatinib response status in HCC was first established. Subsequently, five candidate drugs (Mercaptopurine, AACOCF3, NU1025, Fasudil, and Exisulind) that were capable of reversing lenvatinib resistance signature were initially selected by performing the connectivity map (CMap) analysis, and fasudil finally stood out by conducting a series of cellular functional assays in vitro and xenograft mouse model. Transcriptomics revealed that the co-administration of lenvatinib and fasudil overcame lenvatinib resistance by remodeling the hedgehog signaling pathway. Mechanistically, the feedback activation of EGFR by lenvatinib led to the activation of the GLI2-ABCC1 pathway, which supported the HCC cell's survival and proliferation. Notably, co-administration of lenvatinib and fasudil significantly inhibited IHH, the upstream switch of the hedgehog pathway, to counteract GLI2 activation and finally enhance the effectiveness of lenvatinib. These findings elucidated a novel EGFR-mediated mechanism of lenvatinib resistance and provided a practical approach to overcoming drug resistance in HCC through meaningful drug repurposing strategies.

Macro CD5L+ deteriorates CD8+T cells exhaustion and impairs combination of Gemcitabine-Oxaliplatin-Lenvatinib-anti-PD1 therapy in intrahepatic cholangiocarcinoma.

Intratumoral immune status influences tumor therapeutic response, but it remains largely unclear how the status determines therapies for patients with intrahepatic cholangiocarcinoma. Here, we examine the single-cell transcriptional and TCR profiles of 18 tumor tissues pre- and post- therapy of gemcitabine plus oxaliplatin, in combination with lenvatinib and anti-PD1 antibody for intrahepatic cholangiocarcinoma. We find that high CD8 GZMB+ and CD8 proliferating proportions and a low Macro CD5L+ proportion predict good response to the therapy. In patients with a poor response, the CD8 GZMB+ and CD8 proliferating proportions are increased, but the CD8 GZMK+ proportion is decreased after the therapy. Transition of CD8 proliferating and CD8 GZMB+ to CD8 GZMK+ facilitates good response to the therapy, while Macro CD5L+-CD8 GZMB+ crosstalk impairs the response by increasing CTLA4 in CD8 GZMB+. Anti-CTLA4 antibody reverses resistance of the therapy in intrahepatic cholangiocarcinoma. Our data provide a resource for predicting response of the combination therapy and highlight the importance of CD8+T-cell status conversion and exhaustion induced by Macro CD5L+ in influencing the response, suggesting future avenues for cancer treatment optimization.

PGAM1 Inhibition Promotes HCC Ferroptosis and Synergizes with Anti-PD-1 Immunotherapy.

The combination of immunotherapy and molecular targeted therapy exhibits promising therapeutic efficacy in hepatocellular carcinoma (HCC), but the underlying mechanism is still unclear. Here, phosphoglycerate mutase 1 (PGAM1) is identified as a novel immunometabolic target by using a bioinformatic algorithm based on multiple HCC datasets. PGAM1 is highly expressed in HCC and associated with a poor prognosis and a poor response to immunotherapy. In vitro and in vivo experiments indicate that targeting PGAM1 inhibited HCC cell growth and promoted the infiltration of CD8+ T-cells due to decreased enzymatic activity. Mechanistically, inhibition of PGAM1 promotes HCC cell ferroptosis by downregulating Lipocalin (LCN2) by inducing energy stress and ROS-dependent AKT inhibition, which can also downregulate Programmed death 1-ligand 1 (PD-L1). Moreover, an allosteric PGAM1 inhibitor (KH3) exhibits good antitumor effects in patient-derived xenograft (PDX) models and enhanced the efficacy of anti-PD-1 immunotherapy in subcutaneous and orthotopic HCC models. Taken together, the findings demonstrate that PGAM1 inhibition exerts an antitumor effect by promoting ferroptosis and CD8+ T-cell infiltration and can synergize with anti-PD-1 immunotherapy in HCC. Targeting PGAM1 can be a promising new strategy of "killing two birds with one stone" for HCC treatment.

Integrated single cell and bulk sequencing analysis identifies tumor reactive CXCR6+ CD8 T cells as a predictor of immune infiltration and immunotherapy outcomes in hepatocellular carcinoma.

Background: Various immune cell types in the tumor microenvironment (TME) of hepatocellular carcinoma (HCC) have been identified as important parameters associated with prognosis and responsiveness to immunotherapy. However, how various factors influence immune cell infiltration remains incompletely understood. Hence, we investigated the single cell multi-omics landscape of immune infiltration in HCC, particularly key gene and cell subsets that influence immune infiltration, thus potentially linking the immunotherapy response and immune cell infiltration. Methods: We grouped patients with HCC according to immune cell infiltration scores calculated by single sample gene set enrichment analysis (ssGSEA). Differential expression analysis, functional enrichment, clinical trait association, gene mutation analysis, tumor immune dysfunction and exclusion (TIDE) and prognostic model construction were used to investigate the immune infiltration landscape through multi-omics. Stepwise regression was further used to identify key genes regulating immune infiltration. Single cell analysis was performed to explore expression patterns of candidate genes and investigate associated cellular populations. Correlation analysis, ROC analysis, Immunotherapy cohorts were used to explore and confirm the role of key gene and cellular population in predicting immune infiltration state and immunotherapy response. Immunohistochemistry and multiplexed fluorescence staining were used to further validated our results. Results: Patients with HCC were clustered into high and low immune infiltration groups. Mutations of CTNNB1 and TTN were significantly associated with immune infiltration and altered enrichment of cell populations in the TME. TIDE analysis demonstrated that T cell dysfunction and the T cell exclusion score were elevated in the high and low infiltration groups, respectively. Six risk genes and five risk immune cell types were identified and used to construct risk scores and a nomogram model. CXCR6 and LTA, identified by stepwise regression, were highly associated with immune infiltration. Single cell analysis revealed that LTA was expressed primarily in tumor infiltrating T lymphocytes and partial B lymphocytes, whereas CXCR6 was enriched predominantly in T and NK cells. Notably, CXCR6+ CD8 T cells were characterized as tumor enriched cells that may be potential predictors of high immune infiltration and the immune-checkpoint blockade response, and may serve as therapeutic targets. Conclusion: We constructed a comprehensive single cell and multi-omics landscape of immune infiltration in HCC, and delineated key genes and cellular populations regulating immune infiltration and immunotherapy response, thus providing insights into the mechanisms of immune infiltration and future therapeutic control.

Autophagy suppression facilitates macrophage M2 polarization via increased instability of NF-κB pathway in hepatocellular carcinoma.

The tumor microenvironment is a highly heterogeneous circumstance composed of multiple components, while tumor-associated macrophages (TAMs) are major innate immune cells with highly plastic and are always educated by tumor cells to structure an advantageous pro-tumor immune microenvironment. Despite emerging evidence focalizing the role of autophagy in other immune cells, the regulatory mechanism of autophagy in macrophage polarization remains poorly understood. Herein, we demonstrated that hepatocellular carcinoma (HCC) cells educated macrophages toward M2-like phenotype polarization under the condition of coculture. Moreover, we observed that inhibition of macrophage autophagy promoted M2-like macrophage polarization, while the tendency was impeded when autophagy was motivated. Mechanistically, macrophage autophagy inhibition inactivates the NF-κB pathway by increasing the instability of TAB3 via ubiquitination degradation, which leads to the M2-like phenotype polarization of macrophages. Both immunohistochemistry staining using human HCC tissues and experiment in vivo verified autophagy inhibition is correlated with M2 macrophage polarization. Altogether, we illustrated that macrophage autophagy was involved in the process of HCC cells domesticating M2 macrophage polarization via the NF-κB pathway. These results provide a new target to interfere with the polarization of macrophages to M2-like phenotype during HCC progression.

WDR4/TRIM28 is a novel molecular target linked to lenvatinib resistance that helps retain the stem characteristics in hepatocellular carcinomas.

Hepatocellular carcinoma (HCC) is an aggressive malignancy with few effective treatment options. Lenvatinib is the first-line therapy for HCC but has only limited clinical benefit. Here, we explored the role and mechanism of the WD repeat domain 4 (WDR4) in lenvatinib resistance to improve clinical benefit. We found that lenvatinib-resistant HCC tissues/cells exhibited increased the N7-methylguanosine (m7G) modification and WDR4 expression. By a gain/loss of function experiment, we showed that WDR4 promoted HCC lenvatinib resistance and tumor progress both in vitro and in vivo. By proteomics analysis and RNA immunoprecipitation PCR, we found that tripartite motif protein 28 (trim28) was an important WDR4 target gene. WDR4 promoted TRIM28 expression, further affected target genes expression, and thus increased cell-acquired stemness and lenvatinib resistance. Clinical tissue data showed that TRIM28 expression was correlated with WDR4 levels, and the expression of both was positively correlated with poor prognosis. Our study provides new insight into the role of WDR4, suggesting a potential therapeutic target to enhance the lenvatinib sensitivity of HCC.

Oncogenic miR-93-5p/Gal-9 axis drives CD8 (+) T-cell inactivation and is a therapeutic target for hepatocellular carcinoma immunotherapy.

Evading immune destruction is an emerging hallmark of cancer and a potential key step in tumorigenesis. Immune checkpoint blocker (ICB)-based combination therapies revolutionize the landscape of systemic therapy for HCC. However, the molecular underpinnings governing immune evasion and responses remain unclear. Our study aims to find new regulatory molecules that drive HCC immune escape and tumorigenesis and find new promising immunotherapeutic approaches for HCC. In our study, laser capture microdissection (LCM) and miRNA sequencing combined with in vitro and in vivo experiments identified miR-93-5p as a crucial initiating oncogene during liver progenitor cell (LPC) malignant transformation and immune escape. Mechanistically, miR-93-5p could directly target canonical tumour suppressors such as APC to promote LPC malignant transformation and hepatocarcinogenesis. More importantly, miR-93-5p could induce deviant GAL-9 augmentation to inactivate infiltrated CD8(+) T cells and induce immune evasion by targeting several epigenetic regulators, such as AEBP2, and then regulating H3K4me3/H3K27me3 bivalency. Experiments in C57BL/6 mice demonstrated that blockade of Gal-9 abrogated miR-93-5p-induced HCC progression and improved their prognosis. Clinically, we identified a unique subtype of HCC closely associated with high GAL-9 expression and anti-PD1 treatment resistance. Our study highlights the pivotal role of the miR-93-5p/Gal-9 axis in driving HCC immune escape and tumorigenesis. Blocking GAL-9 is an effective and promising immunotherapeutic approach for HCC.

Inhibition of autophagy in macrophage promotes IL-1ß-mediated hepatocellular carcinoma progression via inflammasome accumulation and self-recruitment.

Hepatocellular carcinoma (HCC) has a complex and changeable tumor microenvironment. Despite emerging evidence focusing on autophagy process within immune cells, the function and regulatory mechanism of macrophage autophagy in tumor progression remains unclear. Our results of multiplex-immunohistochemistry and RNA-sequencing identified the reduced levels of autophagy in tumor macrophages in the HCC microenvironment, associated with a poor prognosis and increased microvascular metastasis in HCC patients. Specifically, HCC suppressed the macrophage autophagy initiation through the up-regulation of mTOR and ULK1 phosphorylation at Ser757. Knockdown of autophagy-related proteins to further inhibit autophagy significantly boosted the metastatic potential of HCC. Mechanistically, the accumulation of NLRP3 inflammasome mediated by autophagy inhibition promoted the cleavage, maturation, and release of IL-1ß, which facilitated the HCC progression, eventually accelerating HCC metastasis via the epithelial-mesenchymal transition. Autophagy inhibition provoked macrophage self-recruitment through the CCL20-CCR6 signaling was also a crucial account of HCC progression. Recruited macrophages mediated the cascade amplification of IL-1ß and CCL20 to form a novel pro-metastatic positive feedback loop through promoting HCC metastasis and increased macrophage recruitment, respectively. Notably, targeting IL-1ß/IL-1 receptor signaling impaired lung metastasis induced by macrophage autophagy inhibition in a mice HCC lung metastasis model. In summary, this study highlighted that inhibition of tumor macrophage autophagy facilitated HCC progression by increasing IL-1ß secretion via NLRP3 inflammasome accumulation and by macrophage self-recruitment through the CCL20 signaling pathway. Interruption of this metastasis-promoting loop by IL-1ß blockade may provide a promising therapeutic strategy for HCC patients.

Loss of 5-hydroxymethylcytosine induces chemotherapy resistance in hepatocellular carcinoma via the 5-hmC/PCAF/AKT axis.

Multidrug resistance is a major challenge in treating advanced hepatocellular carcinoma (HCC). Although recent studies have reported that the multidrug resistance phenotype is associated with abnormal DNA methylation in cancer cells, the epigenetic mechanism underlying multidrug resistance remains unknown. Here, we reported that the level of 5-hydroxymethylcytosine (5-hmC) in human HCC tissues was significantly lower than that in adjacent liver tissues, and reduced 5-hmC significantly correlated with malignant phenotypes, including poor differentiation and microvascular invasion; additionally, loss of 5-hmC was related to chemotherapy resistance in post-transplantation HCC patients. Further, the 5-hmC level was regulated by ten-eleven translocation 2 (TET2), and the reduction of TET2 in HCC contributes to chemotherapy resistance through histone acetyltransferase P300/CBP-associated factor (PCAF) inhibition and AKT signaling hyperactivation. In conclusion, loss of 5-hmC induces chemotherapy resistance through PCAF/AKT axis and is a promising chemosensitivity prediction biomarker and therapeutic target for HCC patients.

Ten-eleven translocation-2 inactivation restrains IL-10-producing regulatory B cells to enable antitumor immunity in hepatocellular carcinoma.

BACKGROUND AND AIMS: IL-10-producing regulatory B cells (IL-10 + B cells), a dominant regulatory B cell (Breg) subset, foster tumor progression. However, the mechanisms underlying their generation in HCC are poorly understood. Ten-eleven translocation-2 (TET2), a predominant epigenetic regulatory enzyme in B cells, regulates gene expression by catalyzing demethylation of 5-methylcytosine into 5-hydroxymethyl cytosine (5hmC). In this study, we investigated the role of TET2 in IL-10 + B cell generation in HCC and its prospects for clinical application. APPROACH AND RESULTS: TET2 activation in B cells triggered by oxidative stress from the HCC microenvironment promoted IL-10 expression, whereas adoptive transfer of Tet2 -deficient B cells suppressed HCC progression. The aryl hydrocarbon receptor is required for TET2 to hydroxylate Il10 . In addition, high levels of IL-10, TET2, and 5hmc in B cells indicate poor prognosis in patients with HCC. Moreover, we determined TET2 activity using 5hmc in B cells to evaluate the efficacy of anti-programmed death 1 (anti-PD-1) therapy. Notably, TET2 inhibition in B cells facilitates antitumor immunity to improve anti-PD-1 therapy for HCC. CONCLUSIONS: Our findings propose a TET2-dependent epigenetic intervention targeting IL-10 + B cell generation during HCC progression and identify the inhibition of TET2 activity as a promising combination therapy with immune checkpoint inhibitors for HCC.

Intratumor microbiome features reveal antitumor potentials of intrahepatic cholangiocarcinoma.

Intrahepatic cholangiocarcinoma (ICC) is a rare malignancy with a high prevalence in China. This study aimed to characterize the ICC tissues' bacterial metagenomics signature and explore its antitumor potential for cancer. In this study, 16S rRNA sequencing was carried out on 99 tissues to characterize the features of intratumoral microbiota, followed by single-cell RNA sequencing (scRNA-seq) and multilevel validation. The presence of microbial DNA in tissues was determined using staining, fluorescence in situ hybridization (FISH), and transmission electron microscopy (TEM). A Gram-positive aerobic bacterium, identified as Staphylococcus capitis, was cultured from fresh tissues. Meanwhile, scRNA-seq showed that intratumoral bacteria could be present in multiple cell types. Using 16S rRNA sequencing, we identified a total of 2,320,287 high-quality reads corresponding to 4,594 OTU (operational taxonomic units) sequences. The most abundant bacterial orders include Burkholderiales, Pseudomonadales, Xanthomonadales, Bacillales and Clostridiales. Alpha and Beta diversity analysis revealed specific features in different tissues. In addition, the content of Paraburkholderia fungorum was significantly higher in the paracancerous tissues and negatively correlated with CA199 (Carbohydrate antigen199) levels. The results of in vitro and in vivo experiments suggest that P. fungorum possesses an antitumor activity against tumors. Metabolomics and transcriptomics showed that P. fungorum could inhibit tumor growth through alanine, aspartate and glutamate metabolism. We determined the characteristic profile of the intratumoral microbiota and the antitumor effect of P. fungorum in ICC.

The clinical implications and molecular features of intrahepatic cholangiocarcinoma with perineural invasion.

BACKGROUND: Perineural invasion (PNI) is associated with metastasis in malignancies, including intrahepatic cholangiocarcinoma (ICC), and is correlated with poor prognosis. METHODS: The study included three large cohorts: ZS-ICC and TMA cohorts from our team, MSK cohort from a public database, and a small cohort named cohort 4. Prognostic implications of PNI were investigated in MSK cohort and TMA cohort. PNI-related genomic and transcriptomic profiles were analyzed in MSK and ZS-ICC cohorts. GO, KEGG, and ssGSEA analyses were performed. Immunohistochemistry was used to investigate the relationship between PNI and markers of neurons, hydrolases, and immune cells. The efficacy of adjuvant therapy in ICC patients with PNI was also assessed. RESULTS: A total of 30.6% and 20.7% ICC patients had PNI in MSK and TMA cohorts respectively. Patients with PNI presented with malignant phenotypes such as high CA19-9, the large bile duct type, lymph node invasion, and shortened overall survival (OS) and relapse-free survival (RFS). Nerves involved in PNI positively express tyrosine hydroxylase (TH), a marker of sympathetic nerves. Patients with PNI showed high mutation frequency of KRAS and an immune suppressive metastasis prone niche of decreased NK cell, increased neutrophil, and elevated PD-L1, CD80, and CD86 expression. Patients with PNI had an extended OS after adjuvant therapy with TEGIO, GEMOX, or capecitabine. CONCLUSION: Our study deciphered the genomic features and the immune suppressive metastasis-prone niche in ICC with PNI. Patients with PNI showed a poor prognosis after surgery but a good response to adjuvant chemotherapy.

Ferroptosis and its interaction with tumor immune microenvironment in liver cancer.

Exploring effective systemic treatments for liver cancer is still a great challenge worldwide. As a novel form of regulated cell death, ferroptosis has been paid more and more attention in the cancer research field. In recent years, targeting ferroptosis has become an encouraging strategy for liver cancer treatment. Cancer cells can be directly killed by inducing ferroptosis; in contrast, ferroptosis can also ameliorate the tumor immunosuppressive microenvironment and sensitize cancers to immunotherapy. Here, we summarize fully current progress in the iron homeostasis in the liver, the internal association between imbalanced iron homeostasis and ferroptosis in liver carcinogenesis and development, as well as ferroptosis-related regulators in liver cancer. Furthermore, we discuss thoroughly the interaction between ferroptosis and tumor immune microenvironment. Finally, we provide certainly a future insight on the potential value of ferroptosis in the immunotherapy of liver cancer.

The influence of 18F-fluorodeoxyglucose positron emission tomography/computed tomography on the N- and M-staging and subsequent clinical management of intrahepatic cholangiocarcinoma.

Background: Intrahepatic cholangiocarcinoma (ICC) is a highly metastatic cancer. 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) enables sensitive tumor and metastasis detection. Our aim is to evaluate the influence of pre-treatment PET/CT on the N- and M-staging and subsequent clinical management in ICC patients. Methods: Between August 2010 and August 2018, 660 consecutive ICC patients, without prior anti-tumor treatments nor other malignancies, were enrolled. The diagnostic performance of PET/CT on the N- and M-staging was compared with conventional imaging, and the preoperative staging accuracy and treatment re-allocation by PET/CT were retrospectively calculated. Survival difference was compared between patients receiving PET/CT or not after propensity score matching. Results: Patients were divided into group A (n=291) and group B (n=369) according to whether PET/CT was performed. Among 291 patients with both PET/CT and conventional imaging for staging in group A, PET/CT showed significantly higher sensitivity (83.0% vs. 70.5%, P=0.001), specificity (88.3% vs. 74.9%, P<0.001) and accuracy (86.3% vs. 73.2%, P<0.001) than conventional imaging in diagnosing regional lymph node metastasis, as well as higher sensitivity (87.8% vs. 67.6%, P<0.001) and accuracy (93.5% vs. 89.3%, P=0.023) in diagnosing distant metastasis. Overall, PET/CT improved the accuracy of preoperative staging from 60.1% to 71.8% (P<0.001), and modified clinical treatment strategy in 5.8% (17/291) of ICC patients, with unique roles in different tumor-node-metastasis (TNM) stages. High tumor-to-non-tumor ratio (TNR) predicted poor overall survival [hazard ratio (HR) = 2.17; 95% confidence interval (CI): 1.49-3.15; P<0.001]. Furthermore, patients performing PET/CT had longer overall survival compared with those without PET/CT (HR =0.74; 95% CI: 0.58-0.93; P=0.011) after propensity score matching. Conclusions: PET/CT was valuable for diagnosing regional lymph node metastasis and distant metastasis in ICC patients, and facilitated accurate tumor staging and optimal treatment allocation.

Tumor associated macrophages-derived exosomes facilitate hepatocellular carcinoma malignance by transferring lncMMPA to tumor cells and activating glycolysis pathway.

BACKGROUND: Tumor-associated macrophages (TAMs), which form a large part of the tumor microenvironment, are normally regulated by metabolic reprogramming. However, the potential mechanisms of the immune-metabolism interaction between hepatocellular carcinoma (HCC) cells and TAMs remain unclear. METHODS: The candidate long non-coding RNAs (lncRNAs) were screened by Smart-seq based scRNA-seq method and then validated by qPCR. Immunostaining analysis was done to examine the levels of markers for TAMs and glycolysis. Exosomes from primary TAMs of human HCC tissues were isolated by centrifugation, and their internalization with lncRNAs was confirmed by immunofluorescence. The underlying mechanism of TAMs-derived exosomal lncRNA to HCC was confirmed by luciferase reporter assay and RNA immunoprecipitation. Metabolism regulation was evaluated through glucose consumption, lactate productions and extracellular acidification rates (ECARs). Mouse xenograft models were used to elucidate the in vivo effect of candidate lncRNAs on tumor growth. RESULTS: TAMs augment the aerobic glycolysis in HCC cells and their proliferation by the extracellular exosome transmission of a myeloid-derived lncRNA, M2 macrophage polarization associated lncRNA (lncMMPA). Mechanistically, lncMMPA not only could polarize M2 macrophage, but also could act as an microRNA sponge to interact with miR-548 s and increase the mRNA level of ALDH1A3, then further promote glucose metabolism and cell proliferation in HCC. Moreover, lncMMPA increased HCC cell multiplication through interacting with miR-548 s in vivo. Clinically, lncMMPA expression associates with glycolysis in TAMs and reduced survival of HCC patients. CONCLUSION: LncMMPA plays an important role in regulating HCC malignancy and metabolic reprogramming of miR-548 s/ALDH1A3 pathway.

KSR2-14-3-3ζ complex serves as a biomarker and potential therapeutic target in sorafenib-resistant hepatocellular carcinoma.

BACKGROUND: Kinase suppressor of Ras 2 (KSR2) is a regulator of MAPK signaling that is overactivated in most hepatocellular carcinoma (HCC). We sought to determine the role of KSR2 in HCC pathogenesis. METHODS: We tested the level of KSR2 in HCC tissues and cell lines by tissue microarray, qPCR, and western blotting. Functionally, we determined the effects of KSR2 on the proliferation, migration, and invasion of HCC cells through colony formation assays, scratch assays, transwell migration assays, and xenograft tumor models. Co-immunoprecipitation (co-IP) experiments were used to assess the interaction of phospho-serine binding protein 14-3-3ζ and KSR2, and the effects of this interaction on growth and proliferation of human HCC cells were tested by co-overexpression and knockdown experiments. Additionally, we used flow cytometry to examine whether the KSR2 and 14-3-3ζ interaction conveys HCC resistance to sorafenib. RESULTS: KSR2 was significantly upregulated in HCC tissues and cell lines, and high KSR2 expression associated with poor prognosis in HCC patients. KSR2 knockdown significantly suppressed HCC cell proliferation, migration, and invasion in vitro and in vivo. Mechanistically, co-IP experiments identified that 14-3-3ζ complexed with KSR2, and elevated 14-3-3ζ increased KSR2 protein levels in HCC cells. Importantly, Kaplan-Meier survival analysis showed that patients with both high KSR2 and high 14-3-3ζ expression levels had the shortest survival times and poorest prognoses. Interestingly, HCC cells overexpressing both KSR2 and 14-3-3ζ, rather than either protein alone, showed hyperactivated MAPK signaling and resistance to sorafenib. CONCLUSIONS: Our results provide new insights into the pro-tumorigenic role of KSR2 and its regulation of the MAPK pathway in HCC. The KSR2-14-3-3ζ interaction may be a therapeutic target to enhance the sorafenib sensitivity of HCC.