Effects Of Sorafenib In Hepatocellular Carcinoma Research Articles

S-palmitoylation of PCSK9 induces sorafenib resistance in liver cancer by activating the PI3K/AKT pathway.

Sorafenib is currently the first-line treatment for advanced hepatocellular carcinoma (HCC). However, sorafenib resistance remains a significant challenge. Aberrant AKT signaling activation is a crucial mechanism driving sorafenib resistance in HCC. Proprotein convertase subtilisin/kexin type 9 (PCSK9) plays a vital role in antitumor immune responses. In this study, we demonstrate that aberrant PCSK9 upregulation promotes cell proliferation and sorafenib resistance in HCC by inducing AKT-S473 phosphorylation. After palmitoylation at cysteine 600, the binding affinity between PCSK9 and tensin homolog (PTEN) is dramatically increased, inducing lysosome-mediated PTEN degradation and subsequent AKT activation. We identify zinc finger DHHC-type palmitoyltransferase 16 (ZDHHC16) as a palmitoyltransferase that promotes PCSK9 palmitoylation at cysteine 600. We also develop a biologically active PCSK9-derived peptide that competitively inhibits PCSK9 palmitoylation, suppressing AKT phosphorylation and augmenting the antitumor effects of sorafenib in HCC.

YAP promotes sorafenib resistance in hepatocellular carcinoma by upregulating survivin.

Sorafenib is the standard first-line treatment for advanced hepatocellular carcinoma (HCC), but its use is hampered by secondary drug resistance. Yes-associated protein (YAP) is a downstream effector of the Hippo signaling pathway, which is crucial for liver tumorigenesis. As yet, however, the mechanism underlying sorafenib resistance and the role of YAP therein is not fully understood and needs to be explored further. Western blotting, flow cytometry and CCK-8 assays were used to assess the role of YAP in HCC sorafenib resistance. Next, qRT-PCR and Western blotting were performed to identify survivin asa YAP downstream effector, and rescue experiments were performed to confirm that YAP induces sorafenib resistance via survivin. Additionally, Western blotting, flow cytometry and in vivo xenograft models were used to evaluate the effect of verteporfin in combination with sorafenib on HCC. We found that sorafenib enhances YAP nuclear accumulation and activation, thereby promoting sorafenib resistance through inhibiting apoptosis in HCC cells. In addition, we found that survivin acts as a downstream mediator of YAP to resist sorafenib-induced apoptosis. Pharmacological inhibition of YAP by verteporfin increased the sensitivity of HCC cells to sorafenib and reversed sorafenib resistance. Moreover, verteporfin in combination with sorafenib significantly suppressed in vivo HCC tumor growth. Our data indicate that YAP promotes sorafenib resistance through upregulation of survivin expression in HCC cells. Targeting YAP may be a therapeutic strategy to improve the antitumor effects of sorafenib in HCC.

LY3214996 relieves acquired resistance to sorafenib in hepatocellular carcinoma cells.

Background: Sorafenib, an oral multi-kinase inhibitor of rapidly accelerated fibrosarcoma; vascular endothelial growth factor receptor-2/3, platelet-derived growth factor receptor, c-Kit, and Flt-3 signaling, is approved for treatment of advanced hepatocellular carcinoma (HCC). However, the benefit of sorafenib is often diminished because of acquired resistance through the reactivation of ERK signaling in sorafenib-resistant HCC cells. In this work, we investigated whether adding LY3214996, a selective ERK1/2 inhibitor, to sorafenib would increase the anti-tumor effectiveness of sorafenib to HCC cells.Methods: The Huh7 cell line was used as a cell model for treatment with sorafenib, LY3214996, and their combination. Phosphorylation of the key kinases in the Ras/Raf/MAPK and PI3K/Akt pathways, protein expression of the cell cycle, and apoptosis migration were assessed with western blot. MTT and colony-formation assays were used to evaluate cell proliferation. Wound-healing assay was used to assess cell migration. Cell cycle and apoptosis analyses were conducted with flow cytometry.Results: LY3214996 decreased phosphorylation of the Ras/Raf/MAPK and PI3K/Akt pathways, including p-c-Raf, p-P90RSK, p-S6K and p-eIF4EBP1 activated by sorafenib, despite increased p-ERK1/2 levels. LY3214996 increased the anti-proliferation, anti-migration, cell-cycle progression, and pro-apoptotic effects of sorafenib on Huh7R cells.Conclusions: Reactivation of ERK1/2 appears to be a molecular mechanism of acquired resistance of HCC to sorafenib. LY3214996 combined with sorafenib enhanced the anti-tumor effects of sorafenib in HCC. These findings form a theoretical basis for trial of LY3214996 combined with sorafenib as second-line treatment of sorafenib-resistant in advanced HCC.

MiR-3609 Decelerates the Clearance of Sorafenib in Hepatocellular Carcinoma Cells by Targeting EPAS-1 and Reducing the Activation of the Pregnane X Receptor Pathway.

BackgroundThe pregnane X receptor (PXR) not only plays an important role in cellular metabolism processes but also induces the resistance of hepatocellular carcinoma (HCC) cells to molecularly targeted drugs by mediating their metabolism and clearance by these cells. Endothelial PAS domain-containing protein 1 (EPAS-1) acts as a coactivator to regulate the transcription factor activity of PXR. In the present study, a microRNA that potentially targets EPAS-1, namely miR-3609, was identified using the miRDB tool.MethodsThe expression of miR-3609 and EPAS-1 was examined by qPCR. Lentiviral particles containing the full-length sequences of miR-3609 (pri-miR-3609) were prepared. The antitumor effect of antitumor agents was examined by the in vitro and in vivo assays.ResultsThe expression of miR-3609 was negatively correlated with that of EPAS-1 in both HCC clinical specimens and paired non-tumor specimens, and the effect of miR-3609 on the expression of EPAS-1 was confirmed by Western blot experiments. Overexpression of miR-3609 decreased the expression of EPAS-1 and, in turn, repressed the activation of the PXR pathway. miR-3609 decreased the transcription factor activation of PXR, repressed its recruitment to its target gene promoter regions, and decreased the expression of its target genes CYP3A4 and P-GP. In addition, miR-3609 decelerated the metabolism and clearance of sorafenib in HCC cells and enhanced the antitumor effect of sorafenib in HCC cells.ConclusionTherefore, the results indicate that miR-3609 decreases the expression of EPAS-1 and enhances the sensitivity of HCC cells to sorafenib.

Protein Kinase B Inactivation Is Associated with Magnolol-Enhanced Therapeutic Efficacy of Sorafenib in Hepatocellular Carcinoma In Vitro and In Vivo.

Although sorafenib, an oral multikinase inhibitor, was approved as a treatment drug of advance hepatocellular carcinoma (HCC), treatment efficacy still requires improvement. Searching for the adjuvant reagent for enhancing sorafenib efficacy remains as a critical issue. Sorafenib has been proved to suppress extracellular signal-regulated kinases (ERK) in HCC; however, protein kinase B (AKT) was not affected by it. Targeting AKT in combination with sorafenib could be an important breakthrough point of HCC treatment. Many herbal compounds and composite formulas have been shown to enhance anti-HCC activity of sorafenib. Magnolol is a bioactive compound extracted from the bark of the Magnolia officinalis and has been shown to induce apoptosis and inhibit cell invasion in HCC in vitro. However, whether magnolol sensitizes HCC to sorafenib is ambiguous. In this study, we indicated that magnolol significantly enhanced sorafenib-diminished tumor cell growth, expression of anti-apoptotic proteins, and migration/invasion ability compared to sorafenib alone. Magnolol significantly boosted sorafenib-induced extrinsic/intrinsic dependent apoptosis pathways in HCC. Notably sorafenib could not reduce protein level of AKT (Ser473), but expression of AKT (Ser473) was significantly decreased by magnolol or magnolol combined with sorafenib. LY294002 as specific AKT inhibitor was used to confirm that AKT inactivation may promote anticancer effect of sorafenib. Taken together, AKT inhibition is associated with magnolol-enhanced the therapeutic effect of sorafenib in HCC. We suggested magnolol as the potential adjuvant which may enhance therapeutic benefits of sorafenib in patients with HCC.

Nek2 augments sorafenib resistance by regulating the ubiquitination and localization of \u03b2-catenin in hepatocellular carcinoma

BackgroundSorafenib is the first-line treatment for advanced-stage hepatocellular carcinoma (HCC). Several studies have shown that the up-regulation of β-catenin plays a role in sorafenib resistance in HCC; however, the mechanism associated with this phenomenon remains elusive.MethodsWestern blotting, flow cytometry, and an evaluation of IC50 values were used to confirm the role of β-catenin in HCC sorafenib resistance. Immunoprecipitation and western blotting were then performed to identify regulatory interactions between β-catenin and Nek2. Further, western blotting, flow cytometry, and an in vivo xenograft model were used to evaluate the function of Nek2 in HCC sorafenib resistance, whereas rescue experiments were performed to confirm that Nek2 induces sorafenib resistance via β-catenin. Finally, western blotting and immunohistochemistry were used to evaluate the expression level of Nek2 in paired HCC and non-tumor tissues.ResultsWe showed that β-catenin could suppress sorafenib-induced apoptosis and cell growth inhibition in HCC cell lines. By screening β-catenin-interacting proteins, we found that Nek2 could bind β-catenin in sorafenib-treated HCC cell lines. Our results also showed that Nek2 stabilizes β-catenin and promotes its translocation to the nucleus, consequently activating the transcription of downstream target genes. We further confirmed that Nek2 could induce sorafenib resistance in HCC cell lines, and that β-catenin was the key element involved in this process. Further, a xenograft tumor model showed that Nek2 knockdown could improve the anti-tumor effect of sorafenib, whereas an analysis of tumor proteins showed that Nek2 regulates β-catenin protein levels and its nuclear translocation in vivo. In addition, Nek2 was found to be up-regulated in HCC tissue, and especially in advanced-stage disease.ConclusionsOur study proves that Nek2 induces HCC sorafenib resistance via β-catenin and suggests a novel therapeutic strategy to improve the anti-tumor effects of sorafenib in HCC.

Questiomycin A stimulates sorafenib-induced cell death via suppression of glucose-regulated protein 78

Hepatocellular carcinoma (HCC) is one of the most difficult cancers to treat owing to the lack of effective chemotherapeutic methods. Sorafenib, the first-line and only available treatment for HCC, extends patient overall survival by several months, with a response rate below 10%. Thus, the identification of an agent that enhances the anticancer effect of sorafenib is critical for the development of therapeutic options for HCC. Endoplasmic reticulum (ER) stress response is one of the methods of sorafenib-induced cell death. Here we report that questiomycin A suppresses expression of GRP78, a cell-protective ER chaperone protein. Analysis of the molecular mechanisms of questiomycin A revealed that this compound stimulated GRP78 protein degradation in an ER stress response-independent manner. Cotreatment with sorafenib and questiomycin A suppressed GRP78 protein expression, which is essential for the stimulation of sorafenib-induced cell death. Moreover, our in vivo study demonstrated that the coadministration of sorafenib and questiomycin A suppressed tumor formation in HCC-induced xenograft models. These results suggest that cotreatment with sorafenib and questiomycin A is a novel therapeutic strategy for HCC by enhancing sorafenib-dependent ER stress-induced cell death, and downregulation of GRP78 is a new target for the stimulation of the therapeutic effects of sorafenib in HCC.

Inhibition of the Wnt/β-catenin signaling pathway improves the anti-tumor effects of sorafenib against hepatocellular carcinoma

Sorafenib, a multikinase inhibitor, is currently the only approved drug for advanced hepatocellular carcinoma (HCC). The current study tested the hypothesis whether inhibition of the Wnt/β-catenin signaling pathway could improve the anti-tumor effects of sorafenib in HCC. ICG-001, a small molecule which blocks the interaction of β-catenin with its transcriptional coactivator CBP, dose-dependently enhanced the growth-suppressive and apoptosis-induction effects of sorafenib in multiple HCC cell lines. Downregulation of β-catenin by RNA interference increased sorafenib sensitivity, whereas overexpression of β-catenin reduced sorafenib sensitivity in Huh7 cells. The sorafenib-sensitization effect of short hairpin RNA (shRNA)-mediated β-catenin downregulation in Huh7 cells was attenuated by β-catenin overexpression. Mechanistically, sorafenib combined with ICG-001 or shRNA-mediated β-catenin downregulation augmented the induction of apoptosis, and resulted in a significant downregulation of Mcl-1 in HCC cells. In Huh7 cell mouse xenograft model, the combination of ICG-001 and sorafenib showed a more significant growth-retarding effect than single agent treatment of sorafenib or ICG-001. Our data indicate that inhibition of the Wnt/β-catenin signaling pathway improves the antitumor effects of sorafenib against HCC in vitro and in vivo.

Down-regulation of SDF1-α expression in tumor microenvironment is associated with aspirin-mediated suppression of the pro-metastasis effect of sorafenib in hepatocellular carcinoma.

Sorafenib is considered to be the first-line therapy for advanced hepatocellular carcinoma (HCC). It significantly delays tumor progression time; however, it increases the invasive and metastatic potential of HCC. Recent studies have shown that aspirin is effective in preventing and treating tumors, and the combination treatment of aspirin and sorafenib significantly suppresses sorafenib-induced intrahepatic metastasis. However, the mechanism through which aspirin suppresses the sorafenib-induced intrahepatic metastasis is still unclear. In this study, we find that sorafenib markedly increases stromal-derived factor 1-alpha (SDF1-α) expression in paratumor and intratumor tissues, and aspirin attenuates sorafenib-induced increase of SDF1-α expression in paratumor and intratumor tissues. Further studies show that SDF1-α improves cell invasion potential of HCC cells, and that AMD3100, a specific inhibitor of SDF1-α receptor CXCR4, suppresses the elevated intrahepatic metastatic potential of HCC induced by sorafenib in vivo. Collectively, this study reveals that the sorafenib-induced increase of SDF1-α expression in paratumor and intratumor microenvironments is suppressed by aspirin, which is associated with aspirin-mediated suppression of the pro-metastasis effect of sorafenib in HCC.

Abstract 5336: Improved antitumor effect of combining WNT/beta-catenin inhibition with sorafenib in hepatocellular carcinoma

Abstract [Background] Sorafenib is currently the only approved systemic agent for advanced hepatocellular carcinoma (HCC); however, its efficacy is limited. Aberrant activation of WNT/β-catenin signaling pathway has been shown to mediate resistance to various types of anti-cancer therapy. We hypothesized that inhibition of WNT/β-catenin signaling pathway would improve the anti-tumor effect of sorafenib in HCC. [Materials and Methods] Human HCC cell lines, including Huh7, HepG2, PLC5, and Hep3B, were included. Inhibition of WNT/β-catenin pathway was achieved by ICG-001, a small molecule disrupting the interaction of cAMP-responsive element binding (CREB)-binding protein (CBP) and β-catenin and inhibiting the β-catenin-mediated transcription activities, or by RNA interference (RNAi)- downregulation of β-catenin. The efficacy of sorafenib combined with WNT/β-catenin pathway inhibition in HCC cells was determined by MTT for cell viability, and by flow cytometry and Western blotting for apoptosis. The in vivo efficacy was evaluated in a subcutaneous xenograft mode of Huh7 cells. [Results] In multiple HCC cell lines, ICG-001 enhanced the anti-proliferative effect of sorafenib dose-dependently; the combination of ICG-001 and sorafenib showed a synergistic antitumor effect. Downregulation of β-catenin by RNAi increased sorafenib sensitivity, whereas overexpression of β-catenin decreased sorafenib sensitivity in Huh7 cells. Furthermore, the sorafenib-sensitization effect by short hairpin RNA (shRNA)-mediated β-catenin downregulation in Huh7 cells was offset by β-catenin overexpression. Mechanistically, sorafenib in combination of ICG-001 or shRNA- mediated β-catenin downregulation augmented the induction of apoptosis, and resulted in a more prominent downregulation of Mcl-1 in HCC cells. Finally, ICG-001 in combination of sorafenib showed a more significantly growth-retarding effect in Huh7 xenograft than either drug alone. [Conclusion] Our data indicate that inhibition of WNT/β- catenin signaling pathway improves the antitumor effect of sorafenib against HCC in vitro and in vivo.(This study was supported by grants NRPB-100CAP1020-2 and NSC-101-2314-B-002-141, 100CAP1020-2). Citation Format: Hsiao-Hui Lin, Wen-Chi Feng, Li-Chun Lu, Yu-Yun Shao, Ann-Lii Cheng, Chih-Hung Hsu. Improved antitumor effect of combining WNT/beta-catenin inhibition with sorafenib in hepatocellular carcinoma. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 5336. doi:10.1158/1538-7445.AM2015-5336

Potential synergistic anti-tumor activity between lenalidomide and sorafenib in hepatocellular carcinoma.

The immune modulatory drug lenalidomide has shown promising anti-tumor activity in a clinical trial of patients with advanced hepatocellular carcinoma (HCC). The present study explored whether lenalidomide can enhance the anti-tumor activity of sorafenib, the standard molecular targeted therapy for HCC. The anti-tumor efficacy of single-agent or combination treatment was measured by change in tumor volume and animal survival using an orthotopic liver cancer model. Distribution of T-cell subpopulations in tumor-infiltrating lymphocytes (TILs) and splenocytes derived from tumor-implanted mice was measured by flow cytometry. Depletion of relevant T-cell subpopulations or cytokines was done by co-administration of relevant antibodies with study drug treatment. Tumor cell apoptosis and tumor angiogenesis were measured by transferase deoxytidyl uridine end labeling assay and immunohistochemical study, respectively. Combination of sorafenib and lenalidomide produced significant synergistic anti-tumor efficacy in terms of tumor growth delay and animal survival. This synergistic effect was associated with a significant increase in interferon-γ expressing CD8(+) lymphocytes in TILs and a significantly higher number of granzyme- or perforin-expressing CD8(+) T cells, compared with vehicle- or single-agent treatment groups. Combination treatment significantly increased apoptotic tumor cells and vascular normalization in tumor tissue. The synergistic anti-tumor effect was abolished after CD8 depletion. Lenalidomide can enhance the anti-tumor effects of sorafenib in HCC through its immune modulatory effects, and CD8(+) TILs play an important role in the anti-tumor synergism.

Aspirin Minimized the Pro-Metastasis Effect of Sorafenib and Improved Survival by Up-Regulating HTATIP2 in Hepatocellular Carcinoma

Background & AimsWe previously demonstrated the pro-metastasis effect of sorafenib in hepatocellular carcinoma (HCC), which is mediated by down-regulation of tumor suppressor HTATIP2. The aim of the present study was to determine whether aspirin minimizes this effect and improves survival.MethodsThe effects of sorafenib, aspirin, and combined sorafenib and aspirin were observed in HCCLM3 and HepG2 xenograft nude mice. Tumor growth, intrahepatic metastasis (IHM), lung metastasis, and survival were assessed. Polymerase chain reaction (PCR) array, real-time (RT)-PCR, and Western blotting were used to examine gene expression. The anti-invasion and anti-metastasis effects of aspirin were studied in HTATIP2-knockdown and HTATIP2-overexpressing HCC cell lines. The molecular mechanism of HTATIP2 regulation by aspirin was explored.ResultsAspirin suppressed the pro-invasion and pro-metastasis effects of sorafenib in HCC and up-regulated HTATIP2 expression. Aspirin did not inhibit the proliferation of HCC cells, but it decreased the invasiveness of HCC with lower expression of HTATIP2 and increased expression of a set of markers, indicating a mesenchymal-to-epithelial transition in tumor cells. The up-regulation of HTATPI2 expression by aspirin is most likely mediated through inhibition of cyclooxygenase (COX) 2 expression.ConclusionsAspirin minimized the pro-metastasis effect of sorafenib by up-regulating the tumor suppressor HTATIP2; this mechanism is mediated through inhibition of COX2.

Abstract 2052: WNT/beta-catenin signaling inhibitors improve the anti-proliferative effect of sorafenib against hepatocellular carcinoma (HCC) cells.

Abstract [Background] Sorafenib, a multikinase inhibitor targeting Raf kinase and vascular endothelial growth factor receptor, is currently the only indicated therapy for patients with advanced hepatocellular carcinoma (HCC). The aberrant activation of WNT/β-catenin signaling pathway, which is associated with the carcinogenetic process of HCC, has been shown to mediate the resistance to various types of anti-cancer therapy. We hypothesized that inhibition of WNT/β-catenin signaling pathway might improve the anti-tumor effect of sorafenib in HCC. [Materials and Methods] Huh7, HepG2, PLC5, and Hep3B HCC cells were treated with sorafenib with or without inhibitors of WNT/β-catenin pathway, and evaluated for viability in vitro. WNT/β-catenin signaling inhibitors included ICG-001 which down-regulates β-catenin/TCF signaling by specifically binding to cyclic AMP response element-binding protein, and XAV939 which targets tankyrases and facilitates degradation of β-catenin. [Results] Sorafenib induced an anti-proliferative effect in HCC cells, with IC50s of 3.5±0.3 μM, 3.7±0.4 μM, 7.7±0.8 μM and 14±0.3 μM for HepG2, Huh7, PLC5, and Hep3B cells, respectively. Upon treated with 10 μM sorafenib for 24 hours, the total cellular amounts of β-catenin were significantly decreased in HepG2 and Huh7 cells, moderately decreased in PLC5 cells, and unchanged in Hep3B cells. In all HCC cells, XAV939 or ICG-001 enhanced the anti-proliferative effect of sorafenib dose-dependently. The median effect analysis showed a synergistic anti-proliferative effect for the combination of ICG-001 plus sorafenib in all HCC cells. [Conclusion] Inhibitors of WNT/β- catenin signaling pathway in combination with sorafenib resulted in an improved anti-tumor effect against HCC in vitro. (The study was supported by the grant NSC 100-2325-B-002-043 from National Science Council of Taiwan) Citation Format: Hsiao-Hui Lin, Wen-Chi Feng, Li-Chun Lu, Yu-Yun Shao, Ann-Lii Cheng, Chih-Hung Hsu. WNT/beta-catenin signaling inhibitors improve the anti-proliferative effect of sorafenib against hepatocellular carcinoma (HCC) cells. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2052. doi:10.1158/1538-7445.AM2013-2052

Abstract B10: Potential synergistic antitumor activity between sorafenib and lenalidomide in an orthotopic murine liver cancer model.

Abstract The immune modulatory drug lenalidomide has shown promising anti-tumor activity in a clinical trial of patients with advanced hepatocellular carcinoma (HCC). The present study explored whether lenalidomide can enhance the anti-tumor activity of sorafenib, the standard molecular targeted therapy for HCC. An orthotopic liver cancer model was developed by injecting the BNL liver cancer cells (from ATCC) into the liver capsule of BALB/c mice. Mice were treated by sorafenib by daily gavage or lenalidomide by daily intra-peritoneal injection, and the anti-tumor efficacy of single-agent or combination treatment was measured by change in tumor volume and animal survival. The number of IFN-γ expressing T-cell sub-populations in tumor-infiltrating lymphocytes (TILs) and the number of IFN-γ expressing tumors-specific CD8+ T cells in splenocytes derived from tumor-implanted mice were measured by flow cytometry. Depletion of relevant T cell sub-populations or cytokines was done by co-administration of relevant antibodies with study drug treatment. TUNEL assay and immunohistochemical study on tumor tissues were done to measure apoptosis and to explore potential biomarkers (Ki67, CD31). Combination of sorafenib (5 mg/kg/day) and lenalidomide (50 mg/kg/day) produced significant synergistic anti-tumor efficacy in terms of tumor growth delay and animal survival. This synergistic effect was associated with a significant increase in IFN-γ expressing CD8+ lymphocytes in TILs and splenocytes. In addition, TILs derived from mice in the combination treatment group had higher number of granzyme- or perforin- expressing CD8+ T cells, compared with vehicle- or single-agent-treatment groups. Combination treatment was associated with a significant increase in apoptotic tumor cells and decrease in microvessel density in tumor tissue. Finally, the synergistic anti-tumor effect was abolished after CD8 depletion. The combination treatment was well tolerated except that leucopenia was common. Our data indicate that lenalidomide can enhance the anti-tumor effects of sorafenib in HCC through its immune modulatory effects and CD8+ T cells play an important role in the anti-tumor synergism. (supported by grants NSC 101-2321-B-002 -014 and NSC 101-2314-B-002-162) Citation Format: Chun-Jung Chang, Da-Liang Ou, Yi-Jang Lin, Ann-Lii Cheng, Chiun Hsu. Potential synergistic antitumor activity between sorafenib and lenalidomide in an orthotopic murine liver cancer model. [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology: Multidisciplinary Science Driving Basic and Clinical Advances; Dec 2-5, 2012; Miami, FL. Philadelphia (PA): AACR; Cancer Res 2013;73(1 Suppl):Abstract nr B10.

IS1-4 - Synergistic Anti-Tumor Effect of Sorafenib in Combination with AKT Inhibitors in Hepatocellular Carcinoma

ABSTRACT Background Sorafenib is currently the only approved agent for hepatocellular carcinoma (HCC). However, its clinical efficacy in HCC is limited. Previous studies indicate that compensatory activation of AKT may contribute to the resistance to sorafenib. We hypothesized that combination of sorafenib and AKT inhibitors could enhance the antitumor effect of sorafenib in HCC. Methods We analyzed the cellular and molecular effects of sorafenib in combination with inhibitors of AKT in human HCC cell lines, and evaluated their combinational effects against HCC in vitro and in vivo. Results HCC cells, including Huh7, Hep3B, and SKhep1 cells, expressed high levels of p-AKT in a prompt and sustained manner upon treated with sorafenib. Down-regulation of AKT by siRNA or inhibition of phospho-AKT by AKT inhibitors (MK-2206 or perifosine) enhanced the anti-proliferative effect of sorafenib in cultured HCC cells. The combination indexes of sorafenib and AKT inhibitors were Conclusions Inhibition of AKT by AKT inhibitors improved the antitumor effect of sorafenib against HCC in vitro and in vivo. Combination of AKT inhibitors and sorafenib warrants further consideration for clinical development in HCC. (The study was supported by NSC97-2628-B-002-004-MY3 and NSC100-2325-B-002-043-.)

Induction of Bim Expression Contributes to the Antitumor Synergy Between Sorafenib and Mitogen-Activated Protein Kinase/Extracellular Signal-Regulated Kinase Kinase Inhibitor CI-1040 in Hepatocellular Carcinoma

Sorafenib has proved survival benefit for patients with advanced hepatocellular carcinoma (HCC). This study explored whether the efficacy of sorafenib can be improved by adding the mitogen-activated protein kinase/extracellular signal-regulated kinase (ERK) kinase (MEK) inhibitor CI-1040 to vertically block the Raf/MEK/ERK pathway. The growth inhibitory effects of sorafenib and CI-1040 were tested in HCC cell lines (Huh-7 and Hep3B) and human umbilical vascular endothelial cells (HUVEC). The potential synergistic growth inhibitory effects were measured by median effect analysis. Apoptosis was measured by flow cytometry. The effects on ERK phosphorylation and levels of apoptosis regulatory proteins were measured by Western blotting. The in vivo antitumor activity of sorafenib and CI-1040 were tested in xenograft HCC models. Combination of sorafenib and CI-1040 synergistically inhibited ERK phosphorylation and cell growth and induced apoptosis in both HCC cells and HUVECs. Increased expression of Bim protein, which correlated with the extent of ERK inhibition, was found in both HCC cells and HUVECs. Knockdown of Bim expression by small interfering RNA partially abrogated the synergistic proapoptotic effects of sorafenib and CI-1040. Combination therapy inhibited tumor growth significantly better than either single agent in the xenograft models. The antitumor effects of sorafenib in HCC can be improved by vertical blockade of Raf/MEK/ERK signaling with CI-1040.