Focal adhesion kinase confers lenvatinib resistance in hepatocellular carcinoma via the regulation of lysine-deficient kinase 1.

Lenvatinib is a clinically effective multikinase inhibitor approved for first-line therapy of advanced hepatocellular carcinoma (HCC). Although resistance against lenvatinib often emerges and limits its antitumor activity, the underlying molecular mechanisms involved in endogenous and acquired resistance remain elusive. In this study, we identified focal adhesion kinase (FAK) as a critical contributor to lenvatinib resistance in HCC. The elevated expression and phosphorylation of FAK were observed in both acquired and endogenous lenvatinib-resistant (LR) HCC cells. Furthermore, inhibition of FAK reversed lenvatinib resistance in vitro and in vivo. Mechanistically, FAK promoted lenvatinib resistance through regulating lysine-deficient kinase 1 (WNK1). Phosphorylation of WNK1 was significantly increased in LR-HCC cells. Further, WNK1 inhibitor WNK463 resensitized either established or endogenous LR-HCC cells to lenvatinib treatment. In addition, overexpression of WNK1 desensitized parental HCC cells to lenvatinib treatment. Conclusively, our results establish a crucial role and novel mechanism of FAK in lenvatinib resistance and suggest that targeting the FAK/WNK1 axis is a promising therapeutic strategy in HCC patients showing lenvatinib resistance.

Targeting LEF1-mediated epithelial-mesenchymal transition reverses lenvatinib resistance in hepatocellular carcinoma.

Acquired resistance is a significant hindrance to clinical application of lenvatinib in unresectable hepatocellular carcinoma (HCC). Further in-depth investigation of resistance mechanisms can help to develop additional therapeutic strategies to overcome or delay resistance. In our study, two lenvatinib-resistant (LR) HCC cell lines were established by treatment with gradient increasing concentration of lenvatinib, named Hep3B-LR and HepG2-LR. Interestingly, continuous lenvatinib treatment reinforced epithelial-mesenchymal transition (EMT), cell migration, and cell invasion. Gene set enrichment analysis (GSEA) enrichment analysis of RNA-sequencing from Hep3B-LR and corresponding parental cells revealed that activation of Wnt signaling pathway was involved in this adaptive process. Active ß-catenin and its downstream target lymphoid enhancer binding factor 1 (LEF1) were significantly elevated in LR HCC cells, which promoted lenvatinib resistance through mediating EMT-related genes. Data analysis based on Gene Expression Omnibus (GEO) and the Cancer Genome Atlas Program (TCGA) databases suggests that LEF1, as a key regulator of EMT, was a novel molecular target linked to lenvatinib resistance and poor prognosis in HCC. Using a small-molecule specific inhibitor ICG001 and knocking down LEF1 showed that targeting LEF1 restored the sensitivity of LR HCC cells to lenvatinib. Our results uncover upregulation of LEF1 confers lenvatinib resistance by facilitating EMT, cell migration, and invasion of LR HCC cells, indicating that LEF1 is a novel therapeutic target for overcoming acquired lenvatinib resistance.

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.

[The regulation of APGAT4 on the growth and lenvatinib resistance of hepatocellular carcinoma].

Objective: To investigate the effect of 1-acyl-sn-glycerol-3-phosphate acyltransferaseδ (APGAT4) on the growth and lenvatinib resistance of hepatocellular carcinoma (HCC), and provide novel targets for HCC treatment. Methods: Using the bioinformatics methods to screen out upregulated genes in lenvatinib resistant cell lines from GEO dataset and survival related genes from TCGA dataset. Immumohistochemical staining was used to detect the expression AGPAT4 in HCC tissues, and its correlation with patients' survival. CCK8, EdU, cell cycle, and cell apoptosis assays were used to investigate the impact of role AGPAT4 on the proliferation and lenvatinib reistance of HCC cells. AGPAT4 stable knockdown cell line and subcutaneous nude mouse model were established to test the therapeutic effects of Lenvatinib. Analysis of variance was used to compare the differences between data sets. Results: APGAT4 was the common factor that predicted poor survival and Lenvatinib resistance. The mRNA and protein levels of APGAT4 were significantly upregulated in HCC tissues compared to the para-tumor tissues (P < 0.05). Using siRNA could significantly knocked down the mRNA and protein expression of APGAT4 in HCC cell lines Hep3B and HCCLM3. Compared with the control group, the proliferation ability of HCC cell lines (Hep3B and HCCLM3) in APGAT4 knockdown group was significantly inhibited, and the cell cycle was arrested in G2/M phase (P < 0.05). In addition, compared to the control group, HCC cell lines (Hep3B and HCCLM3) in APGAT4 knockdown group showed significant decrease in the Lenvatinib half maximal inhibitory concentration, and were more sensitive to lenvatinib-induced apoptosis (P < 0.05). In HCC subcutaneous nude mouse model, compared to the control group, the growth of tumor in APGAT4 knockdown group was significantly suppressed, and more apoptosis cells were induced (P < 0.05). Conclusion: APGAT4 promotes the growth and Lenvatinib resistance of HCC, which is a potential target for HCC treatment. Targeting APGAT4 treatment is conducive to inhibit the growth and Lenvatinib resistance of HCC.

Sophoridine suppresses lenvatinib-resistant hepatocellular carcinoma growth by inhibiting RAS/MEK/ERK axis via decreasing VEGFR2 expression.

Hepatocellular carcinoma (HCC) is one of the most lethal cancer types with insufficient approved therapies, among which lenvatinib is a newly approved multi-targeted tyrosine kinase inhibitor for frontline advanced HCC treatment. However, resistance to lenvatinib has been reported in HCC treatment recently, which limits the clinical benefits of lenvatinib. This study aims to investigate the underlying mechanism of lenvatinib resistance and explore the potential drug to improve the treatment for lenvatinib-resistant (LR) HCC. Here, we developed two human LR HCC cell lines by culturing with long-term exposure to lenvatinib. Results showed that the vascular endothelial growth factor receptors (VEGFR)2 expression and its downstream RAS/MEK/ERK signalling were obviously up-regulated in LR HCC cells, whereas the expression of VEGFR1, VEGFR3, FGFR1-4 and PDGFRα/ß showed no difference. Furthermore, ETS-1 was identified to be responsible for VEGFR2 mediated lenvatinib resistance. The cell models were further used to explore the potential strategies for restoration of sensitivity of lenvatinib. Sophoridine, an alkaloid extraction, inhibited the proliferation, colony formation, cell migration and increased apoptosis of LR HCC cells. In vivo and in vitro results showed Sophoridine could further sensitize the therapeutic of lenvatinib against LR HCC. Mechanism studies revealed that Sophoridine decreased ETS-1 expression to down-regulate VEGFR2 expression along with downstream RAS/MEK/ERK axis in LR HCC cells. Hence, our study revealed that up-regulated VEGFR2 expression could be a predicator of the resistance of lenvatinib treatment against HCC and provided a potential candidate to restore the sensitivity of lenvatinib for HCC treatment.

HDAC Inhibition Sensitize Hepatocellular Carcinoma to Lenvatinib via Suppressing AKT Activation.

Hepatocellular carcinoma (HCC) is a deadly malignancy with limited treatment options. As a first-line treatment for advanced HCC, Lenvatinib has been applicated in clinic since 2018. Resistance to Lenvatinib, however, has severely restricted the clinical benefits of this drug. Therefore, it is urgent to explore the potential resistance mechanisms of Lenvatinib and identify appropriate methods to reduce resistance for the treatment of HCC. We identified SAHA, a HDAC inhibitor, to have effective anti-tumor activity against Lenvatinib-resistant HCC organoids by screening a customized drug library. Mechanism analysis revealed that SAHA upregulates PTEN expression and suppresses AKT signaling, which contributes to reversing Lenvatinib resistance in liver cancer cells. Furthermore, combinational application of Lenvatinib and HDAC inhibitor or AKT inhibitor synergistically inhibits HCC cell proliferation and induces cell apoptosis. Finally, we confirmed the synergistic effects of Lenvatinib and SAHA, or AZD5363 in primary liver cancer patient derived organoids. Collectively, these findings may enable the development of Lenvatinib combination therapies for HCC.

Deubiquitination of CIB1 by USP14 promotes lenvatinib resistance via the PAK1-ERK1/2 axis in hepatocellular carcinoma.

Background: Lenvatinib is the most common multitarget receptor tyrosine kinase inhibitor for the treatment of advanced hepatocellular carcinoma (HCC). Acquired resistance to lenvatinib is one of the major factors leading to the failure of HCC treatment, but the underlying mechanism has not been fully characterized. Methods: We established lenvatinib-resistant cell lines, cell-derived xenografts (CDXs) and patient-derived xenografts (PDXs) and obtained lenvatinib-resistant HCC tumor tissues for further study. Results: We found that ubiquitin-specific protease 14 (USP14) was significantly increased in lenvatinib-resistant HCC cells and tumors. Silencing USP14 significantly attenuated lenvatinib resistance in vitro and in vivo. Mechanistically, USP14 directly interacts with and stabilizes calcium- and integrin-binding protein 1 (CIB1) by reversing K48-linked proteolytic ubiquitination at K24, thus facilitating the P21-activated kinase 1 (PAK1)-ERK1/2 signaling axis. Moreover, in vivo adeno-associated virus 9 mediated transduction of CIB1 promoted lenvatinib resistance in PDXs, whereas CIB1 knockdown resensitized the response of PDXs to lenvatinib. Conclusions: These findings provide new insights into the role of CIB1/PAK1-ERK1/2 signaling in lenvatinib resistance in HCC. Targeting CIB1 and its pathways may be a novel pharmaceutical intervention for the treatment of lenvatinib-resistant HCC.

Reserpine, a novel N6-methyladenosine regulator, reverses Lenvatinib resistance in hepatocellular carcinoma.

BACKGROUND: Hepatocellular carcinoma (HCC) is an aggressive malignancy and a growing global health problem. Reserpine (Res), a plant-derived hypertension drug, has been reported to possess anti-tumor efficacy. However, the role and function of Res in N6-methyladenosine (m6A) regulation and Lenvatinib (Len) resistance in HCC have not been clarified. PURPOSE: To verify whether Res can be used as a natural small-molecule regulator of m6A to reverse Len resistance in HCC. METHODS: Dot blotting, Western blotting and m6A quantification were used to compare and analyze the differential expression of m6A and its methyltransferase METTL3. Western blotting, Real-Time PCR (RT-PCR), cellular thermal shift assay (CETSA) and molecular docking were used to explore the mechanism of interaction between Res and m6A. The effects of Res on the biological characteristics of Lenvatinib-resistant HCC cells were investigated through CCK-8, clone formation, and Transwell assays. Cell line-derived xenograft (CDX) and patient-derived xenograft (PDX) mouse models were used to assess the ability of Res to reverse Len resistance in vivo. MeRIP m6A sequencing, PATHWAY analysis and Western blotting were used to analyze the downstream signaling pathways and genes involved in Res-mediated reversal of Len resistance. RESULTS: Len resistance in HCC is related to the increased m6A level and the high expression of METTL3. Res affects the activity of METTL3 protein by binding to it, thereby downregulating the level of m6A. In vitro study showed that Res can sensitize HCC cells to the anti-tumor effects of Len treatment, including blocking proliferation, inhibiting migration, and inducing apoptosis. Len-resistant CDX and PDX models revealed that Res can reverse the resistant phenotype, with the tumor inhibition rates of 77.46 % and 62.1 %, respectively, when combined with Len treatment. Analysis of xenograft tissues showed that the combination of Res and Len down-regulates the m6A level, reduces proliferation biomarkers, and induces apoptosis, which is consistent with the in vitro data. Mechanistically, our preliminary results indicate that Res can up-regulate the SMAD3 level by down-regulating m6A in Len-resistant cells. CONCLUSIONS: Reserpine, a small-molecule regulator of m6A, reverses Lenvatinib-resistant phenotypes, including proliferation, migration and anti-apoptosis, in vitro and in vivo by targeting SMAD3 and down-regulating the m6A level in HCC.

Lactylation-Driven IGF2BP3-Mediated Serine Metabolism Reprogramming and RNA m6A-Modification Promotes Lenvatinib Resistance in HCC.

Acquired resistance remains a bottleneck for molecular-targeted therapy in advanced hepatocellular carcinoma (HCC). Metabolic adaptation and epigenetic remodeling are recognized as hallmarks of cancer that may contribute to acquired resistance. In various lenvatinib-resistant models, increased glycolysis leads to lactate accumulation and lysine lactylation of IGF2BP3. This lactylation is crucial for capturing PCK2 and NRF2 mRNAs, thereby enhancing their expression. This process reprograms serine metabolism and strengthens the antioxidant defense system. Additionally, altered serine metabolism increases the availability of methylated substrates, such as S-adenosylmethionine (SAM), for N6-methyladenosine (m6A) methylation of PCK2 and NRF2 mRNAs. The lactylated IGF2BP3-PCK2-SAM-m6A loop maintains elevated PCK2 and NRF2 levels, enhancing the antioxidant system and promoting lenvatinib resistance in HCC. Treatment with liposomes carrying siRNAs targeting IGF2BP3 or the glycolysis inhibitor 2-DG restored lenvatinib sensitivity in vivo. These findings highlight the connection between metabolic reprogramming and epigenetic regulation and suggest that targeting metabolic pathways may offer new strategies to overcome lenvatinib resistance in HCC.

Pharmacogenomic profiling of intra-tumor heterogeneity using a large organoid biobank of liver cancer.

Inter- and intra-tumor heterogeneity is a major hurdle in primary liver cancer (PLC) precision therapy. Here, we establish a PLC biobank, consisting of 399 tumor organoids derived from 144 patients, which recapitulates histopathology and genomic landscape of parental tumors, and is reliable for drug sensitivity screening, as evidenced by both in vivo models and patient response. Integrative analysis dissects PLC heterogeneity, regarding genomic/transcriptomic characteristics and sensitivity to seven clinically relevant drugs, as well as clinical associations. Pharmacogenomic analysis identifies and validates multi-gene expression signatures predicting drug response for better patient stratification. Furthermore, we reveal c-Jun as a major mediator of lenvatinib resistance through JNK and ß-catenin signaling. A compound (PKUF-01) comprising moieties of lenvatinib and veratramine (c-Jun inhibitor) is synthesized and screened, exhibiting a marked synergistic effect. Together, our study characterizes the landscape of PLC heterogeneity, develops predictive biomarker panels, and identifies a lenvatinib-resistant mechanism for combination therapy.

NQO1 Mediates Lenvatinib Resistance by Regulating ROS-induced Apoptosis in Hepatocellular Carcinoma.

OBJECTIVE: Hepatocellular carcinoma (HCC) is the third leading cause of cancer-associated death worldwide. As a first-line drug for advanced HCC treatment, lenvatinib faces a significant hurdle due to the development of both intrinsic and acquired resistance among patients, and the underlying mechanism remains largely unknown. The present study aims to identify the pivotal gene responsible for lenvatinib resistance in HCC, explore the potential molecular mechanism, and propose combinatorial therapeutic targets for HCC management. METHODS: Cell viability and colony formation assays were conducted to evaluate the sensitivity of cells to lenvatinib and dicoumarol. RNA-Seq was used to determine the differences in transcriptome between parental cells and lenvatinib-resistant (LR) cells. The upregulated genes were analyzed by GO and KEGG analyses. Then, qPCR and Western blotting were employed to determine the relative gene expression levels. Afterwards, the intracellular reactive oxygen species (ROS) and apoptosis were detected by flow cytometry. RESULTS: PLC-LR and Hep3B-LR were established. There was a total of 116 significantly upregulated genes common to both LR cell lines. The GO and KEGG analyses indicated that these genes were involved in oxidoreductase and dehydrogenase activities, and reactive oxygen species pathways. Notably, NAD(P)H:quinone oxidoreductase 1 (NQO1) was highly expressed in LR cells, and was involved in the lenvatinib resistance. The high expression of NQO1 decreased the production of ROS induced by lenvatinib, and subsequently suppressed the apoptosis. The combination of lenvatinib and NQO1 inhibitor, dicoumarol, reversed the resistance of LR cells. CONCLUSION: The high NQO1 expression in HCC cells impedes the lenvatinib-induced apoptosis by regulating the ROS levels, thereby promoting lenvatinib resistance in HCC cells.

METTL3-m6A-EGFR-axis drives lenvatinib resistance in hepatocellular carcinoma.

Lenvatinib is emerging as the first-line therapeutic option for advanced hepatocellular carcinoma (HCC), but drug resistance remains a major hurdle for its long-term therapy efficiency in clinic. N6-methyladenosine (m6A) is the most abundant mRNA modification. Here, we aimed to investigate the modulatory effects and underlying mechanisms of m6A in lenvatinib resistance in HCC. Our data revealed that m6A mRNA modification was significantly upregulated in the HCC lenvatinib resistance (HCC-LR) cells compared to parental cells. Methyltransferase-like 3 (METTL3) was the most significantly upregulated protein among the m6A regulators. Either genetic or pharmacological inhibition of m6A methylation through METTL3 deactivation in primary resistant cell line MHCC97H and acquired resistant Huh7-LR cells decreased cell proliferation and increased cell apoptosis upon lenvatinib treatment in vitro and in vivo. In addition, the specific METTL3 inhibitor STM2457 improved tumor response to lenvatinib in multiple mouse HCC models, including subcutaneous, orthotopic and hydrodynamic models. The MeRIP-seq results showed that epidermal growth factor receptor (EGFR) was a downstream target of METTL3. EGFR overexpression abrogated the METTL3 knocked down-induced cell growth arrest upon lenvatinib treatment in HCC-LR cells. Thus, we concluded that targeting METTL3 using specific inhibitor STM2457 improved the sensitivity to lenvatinib in vitro and in vivo, indicating that METTL3 may be a potential therapeutic target to overcome lenvatinib resistance in HCC.

Targeting LINC01607 sensitizes hepatocellular carcinoma to Lenvatinib via suppressing mitophagy.

Lenvatinib is a standard therapy option for advanced hepatocellular carcinoma (HCC), but resistance limits clinical benefits. In this study, we identified inhibition of ROS levels and reduced redox status in Lenvatinib-resistant HCC. Integrating RNA-seq with unbiased whole-genome CRISPR-Cas9 screen analysis indicated LINC01607 regulated the P62 to enhance drug resistance by affecting mitophagy and antioxidant pathways. Underlying mechanisms were investigated both in vitro and in vivo. We initially confirmed that LINC01607, as a competing endogenous RNA (ceRNA) competing with mirRNA-892b, triggered protective mitophagy by upregulating P62, which reduced ROS levels and promoted drug resistance. Furthermore, LINC01607 was proved to resist oxidative stress by regulating the P62-Nrf2 axis, which transcriptionally regulated the expression of LINC01607 to form a positive feedback loop. Finally, silencing LINC01607 combined with Lenvatinib reversed resistance in animal and patient-derived organoid models. In conclusion, we proposed a novel mechanism of Lenvatinib resistance involving ROS homeostasis. This work contributed to understanding redox homeostasis-related drug resistance and provided new therapeutic targets and strategies for HCC patients.

Lnc-ZEB2-19 Inhibits the Progression and Lenvatinib Resistance of Hepatocellular Carcinoma by Attenuating the NF-κB Signaling Pathway through the TRA2A/RSPH14 Axis.

Long non-coding RNAs have been reported to play a crucial role in tumor progression in hepatocellular carcinoma (HCC). Lnc-ZEB2-19 has been validated to be deficiently expressed in HCC. However, the capabilities and underlying mechanisms of lnc-ZEB2-19 remain uncertain. In this study, we verified that the downregulation of lnc-ZEB2-19 was prevalent in HCC and significantly correlated with the unfavorable prognosis. Further in vitro and in vivo verified that lnc-ZEB2-19 notably inhibited the proliferation, metastasis, stemness, and lenvatinib resistance (LR) of HCC cells. Mechanistically, lnc-ZEB2-19 inhibited HCC progression and LR by specifically binding to transformer 2α (TRA2A) and promoting its degradation, which resulted in the instability of RSPH14 mRNA, leading to the downregulation of Rela(p65) and p-Rela(p-p65). Furthermore, rescue assays showed that silencing RSPH14 partially restrained the effect of knockdown expression of lnc-ZEB2-19 on HCC cell metastatic ability and stemness. The findings describe a novel regulatory axis, lnc-ZEB2-19/TRA2A/RSPH14, downregulating the nuclear factor kappa B to inhibit HCC progression and LR.

AKR1C1 overexpression leads to lenvatinib resistance in hepatocellular carcinoma.

Background: Lenvatinib is an orally administered drug that works as a multi-targeted tyrosine kinase inhibitor. It has been approved as a first-line drug after sorafenib in hepatocellular carcinoma (HCC). However, little is currently known about its treatment, targets, and possible resistance in HCC. Methods: The proliferation of HCC cells was evaluated using colony formation, 5-ethynyl-2'-deoxyuridine (EDU), wound healing, cell counting kit-8 (CCK-8), and xenograft tumor assays. RNA sequencing (RNA-seq) was utilized to comprehensively examine variations in highly metastatic human liver cancer cells (MHCC-97H) cells (treated with various doses of lenvatinib) at the transcriptomic level. Protein interactions and functions were predicted using Cytoscape-generated networks and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment, while the proportions of 22 immune cell types were examined with CIBERSORT. Aldo-keto reductase family 1 member C1 (AKR1C1) expression was verified by quantitative real time polymerase chain reaction (qRT-PCR) or immunohistochemistry in HCC cells and liver tissues. Micro ribonucleic acid (miRNAs) were predicted using online tools and potential drugs were screened using the Genomics of Drug Sensitivity in Cancer (GDSC) database. Results: Lenvatinib inhibited the proliferation of HCC cells. The obtained results suggested that an elevated level of AKR1C1 expression was observed in lenvatinib-resistant (LR) cell lines and HCC tissues, whereas low AKR1C1 expression inhibited the proliferation of HCC cells. Circulating microRNA 4644 (miR-4644) was predicted to serve as a promising biomarker for the early diagnosis of lenvatinib resistance. Online data analysis of LR cells showed significant differences in the immune microenvironment and drug sensitivity compared with their parental counterparts. Conclusions: Taken together, AKR1C1 may serve as a candidate therapeutic target for LR liver cancer patients.

Characterization of Cisplatin Effects in Lenvatinib-resistant Hepatocellular Carcinoma Cells.

BACKGROUND/AIM: Drug resistance to molecular targeted agents, such as lenvatinib, is an important issue. The aim of this study was to explore the mechanism of lenvatinib resistance and to investigate potential drugs that may improve the treatment of lenvatinib-resistant (LR) hepatocellular carcinoma (HCC). MATERIALS AND METHODS: LR cells were developed by long-term culture under lenvatinib exposure. We analyzed the biological characteristics of LR cells in vitro, and investigated the antitumor effects and endogenous mechanisms of cisplatin in LR cells. RESULTS: The proliferative potential of LR cells was enhanced by activation of ERK signaling and changes in several miRNAs. Cisplatin inhibited cell proliferation of LR cells and induced G2/M cell cycle arrest. Furthermore, cisplatin triggered the DNA damage response, via the ATM/ATR-Chk1/Chk2 signaling pathway. CONCLUSION: Proliferation of LR cells was induced upon ERK signaling activation. Cisplatin exerted antitumor effects in LR cells and was involved in the regulation of miRNAs associated with drug resistance.

circRNA circMED27 acts as a prognostic factor and mediator to promote lenvatinib resistance of hepatocellular carcinoma.

Circular RNAs (circRNAs) have been proven to play key roles in the development and progression of various types of cancers. However, there were no reported studies on the roles of circRNA mediator complex subunit 27 (circMED27) in tumors including hepatocellular carcinoma (HCC). In this study, we found that circMED27 was significantly increased in HCC serum and that higher levels of circMED27 were correlated with bad clinical characteristics and poor prognoses of patients with HCC. Furthermore, upregulated circMED27 promoted HCC resistance to lenvatinib. Our mechanistic investigations revealed that circMED27 functions as a competing endogenous RNA (ceRNA) for miR-655-3p to upregulate ubiquitin-specific peptidase 28 (USP28) expression. Thus, we are led to conclude that circMED27 acts as a potential therapeutic target for HCC patients receiving lenvatinib therapy and may represent a promising molecular biomarker for forecasting lenvatinib-resistant HCC.

CircPAK1 promotes the progression of hepatocellular carcinoma via modulation of YAP nucleus localization by interacting with 14-3-3ζ.

BACKGROUND: Circular RNA (circRNA), a new class of non-coding RNA, has obvious correlations with the occurrence and development of many diseases, including tumors. This study aimed to investigate the potential roles of circPAK1 in hepatocellular carcinoma (HCC). METHODS: High-throughput sequencing was performed on 3 pairs of HCC and matched normal tissues to determine the upregulated circRNAs. The expression level of circPAK1 was detected by qRT-PCR in HCC and paired with normal liver tissue samples. The effects of circPAK1 on proliferation, invasion, metastasis and apoptosis of HCC cells were evaluated by in vitro and in vivo experiments. We also constructed Chitosan/si-circPAK1 (CS/si-circPAK1) nanocomplexes using Chitosan material to evaluate its in vivo therapeutic effect on HCC. High-throughput sequencing, RNA-sequencing, RNA probe pull-down, RNA immunoprecipitation and Co-Immunoprecipitation assays were performed to explore the relationship between circPAK1, 14-3-3ζ, p-LATS1 and YAP. Exosomes isolated from lenvatinib-resistant HCC cell lines were used to evaluate the relationship between exosomal circPAK1 and lenvatinib resistance. RESULTS: CircPAK1, a novel circRNA, is highly expressed in HCC tumor tissues and cell lines as well as correlated with poor outcomes in HCC patients. Functionally, circPAK1 knockdown inhibited HCC cell proliferation, migration, invasion and angiogenesis while circPAK1 overexpression promoted HCC progression. The tumor-promoting phenotypes of circPAK1 on HCC were also confirmed by animal experiments. Importantly, the application of CS/si-circPAK1 nanocomplexes showed a better therapeutic effect on tumor growth and metastasis. Mechanistically, circPAK1 enhanced HCC progression by inactivating the Hippo signaling pathway, and this kind of inactivation is based on its competitively binding of 14-3-3 ζ with YAP, which weakens the recruitment and cytoplasmic fixation of 14-3-3 ζ to YAP, thus promoting YAP nucleus localization. Additionally, circPAK1 could be transported by exosomes from lenvatinib-resistant cells to sensitive cells and induce lenvatinib resistance of receipt cells. CONCLUSION: CircPAK1 exerts its oncogenic function by competitively binding 14-3-3 ζ with YAP, thus promoting YAP nucleus localization, leading to the inactivation of a Hippo signaling pathway. Exosomal circPAK1 may drive resistance to lenvatinib, providing a potential therapeutic target for HCC patients.

Co-administration of MDR1 and BCRP or EGFR/PI3K inhibitors overcomes lenvatinib resistance in hepatocellular carcinoma.

Lenvatinib is the first-line treatment for hepatocellular carcinoma (HCC), the most common type of primary liver cancer; however, some patients become refractory to lenvatinib. The underlying mechanism of lenvatinib resistance (LR) in patients with advanced HCC remains unclear. We focused on exploring the potential mechanism of LR and novel treatments of lenvatinib-resistant HCC. In particular, we established a Huh7 LR cell line and performed in vitro, bioinformatic, and biochemical assays. Additionally, we used a Huh7-LR cell-derived xenograft mouse model to confirm the results in vivo. Following LR induction, multidrug resistance protein 1 (MDR1) and breast cancer resistance protein (BCRP) transporters were markedly upregulated, and the epidermal growth factor receptor (EGFR), MEK/ERK, and PI3K/AKT pathways were activated. In vitro, the co-administration of elacridar, a dual MDR1 and BCRP inhibitor, with lenvatinib inhibited proliferation and induced apoptosis of LR cells. These effects might be due to inhibiting cancer stem-like cells (CSCs) properties, by decreasing colony formation and downregulating CD133, EpCAM, SOX-9, and c-Myc expression. Moreover, the co-administration of gefitinib, an EGFR inhibitor, with lenvatinib retarded proliferation and induced apoptosis of LR cells. These similar effects might be caused by the inhibition of EGFR-mediated MEK/ERK and PI3K/AKT pathway activation. In vivo, co-administration of lenvatinib with elacridar or gefitinib suppressed tumour growth and angiogenesis. Therefore, inhibiting MDR1 and BCRP transporters or targeting the EGFR/PI3K pathway might overcome LR in HCC. Notably, lenvatinib should be used to treat HCC after LR induction owing to its role in inhibiting tumour proliferation and angiogenesis. Our findings could help develop novel and effective treatment strategies for HCC.

IRF2 regulates cellular survival and Lenvatinib-sensitivity of hepatocellular carcinoma (HCC) through regulating ß-catenin.

Hepatocellular carcinoma (HCC) is the third leading cause of cancer-related death worldwide. Lenvatinib oral chemotherapy is approved as a first-line treatment of patients with unresectable HCC. The efficacy and therapeutic duration of lenvatinib are limited by drug resistance, and the mechanism is unclear. IRF2 is a constitutive transcription factor associated with the development of various cancers by regulating cancer cell growth, apoptosis, and drug resistance. However, the potential role of IRF2 in lenvatinib resistance in HCC has not been explored. In this study, we found that IRF2 promoted proliferation, inhibited apoptosis, and increased lenvatinib resistance of HCC cells by regulating ß-catenin expression. Silencing IRF2 downregulated the expression of ß-catenin, while overexpressing IRF2 upregulated ß-catenin. Moreover, the expression of ß-catenin and IRF2 was positively correlated in HCC tissues. Inhibiting ß-catenin with XAV-939 effectively abrogated ß-catenin expression caused by lenvatinib treatment. These findings identify an important function of IRF2 in HCC and demonstrate a mechanism of lenvatinib resistance of HCC cells. Targeting IRF2 may be a potential strategy to improve the therapeutic effect of lenvatinib on HCC.