Combined anti-tumor effects of IFN-α and sorafenib on hepatocellular carcinoma in vitro and in vivo

The Role of Bcl-2 Family Proteins and Sorafenib Resistance in Hepatocellular Carcinoma

Liver cancer has been reported to be one of the most malignant diseases in the world. It is late diagnosis consequently leads to a difficult treatment, as the cancer reached an advanced stage. Hepatocellular carcinoma (HCC) is the primary type of cancer diagnosed in the liver, with deadly characteristics and a poor prognosis. The first-in-line treatment for advanced HCC is sorafenib. Sorafenib acts by inhibiting cell proliferation and by inducing apoptosis as well as blocks receptors associated with these mechanisms. Due to its constant use, sorafenib resistance has been described, especially to proteins of the Bcl-2 family, and their overexpression of Bcl-XL and Mcl-1. This review focuses on the role of the Bcl-2 proteins in relation to sorafenib resistance as a consequence of first-in-line treatment in HCC.

Mechanism of action and treatment of type I interferon in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) caused by HBV, HCV infection, and other factors is one of the most common malignancies in the world. Although, percutaneous treatments such as surgery, ethanol injection, radiofrequency ablation, and transcatheter treatments such as arterial chemoembolization are useful for local tumor control, they are not sufficient to improve the prognosis of patients with HCC. External interferon agents that induce interferon-related genes or type I interferon in combination with other drugs can reduce the recurrence rate and improve survival in HCC patients after surgery. Therefore, in this review, we focus on recent advances in the mechanism of action of type I interferons, emerging therapies, and potential therapeutic strategies for the treatment of HCC using IFNs.

Therapeutic efficacy of sorafenib and plant-derived phytochemicals in human colorectal cancer cells

BACKGROUND

The present study aimed to investigate the sequence-dependent anticancer effects of combined treatment with sorafenib (Sora), a Food and Drug Administration-approved multikinase inhibitor drug, and plant-derived phytochemicals (PPCs) on human colorectal cancer (CRC) cell growth, and proteins associated with the control of cell cycle and apoptosis.

METHODS

The cytotoxic effects of 14 PPCs on CRL1554 fibroblast cells were determined using an MTT assay. Moreover, the cytotoxicity of Sora, PPCs, and a combination of both on CRC cells were also investigated. Cell cycle analysis was performed using flow cytometry, and cell apoptosis was investigated using DNA fragmentation, Annexin V/propidium iodide double staining, and mitochondrial membrane potential analyses. The cell cycle- and apoptosis-associated protein expression levels were analysed using western blotting.

RESULTS

Based on their low levels of cytotoxicity in CRL1554 cells at ≤ 20%, curcumin, quercetin, kaempferol, and resveratrol were selected for use in subsequent experiments. The combined treatment of sora and PPCs caused levels of CRC cytotoxicity in a dose-, cell type-, and schedule-dependent manner. Moreover, the combined treatment of CRC cells arrested cell growth at the S and G2/M phases, induced apoptotic cell death, caused extensive mitochondrial membrane damage, and altered the expression of the cell cycle and apoptotic proteins.

CONCLUSIONS

Results of the present study highlighted a difference in the level of sora efficacy in CRC cells when combined with PPCs. Further in vivo and clinical studies using the combined treatment of sora and PPCs are required to determine their potential as a novel therapeutic strategy for CRCs.

Immunotherapy of hepatocellular carcinoma: recent progress and new strategy

Due to its widespread occurrence and high mortality rate, hepatocellular carcinoma (HCC) is an abhorrent kind of cancer. Immunotherapy is a hot spot in the field of cancer treatment, represented by immune checkpoint inhibitors (ICIs), which aim to improve the immune system's ability to recognize, target and eliminate cancer cells. The composition of the HCC immune microenvironment is the result of the interaction of immunosuppressive cells, immune effector cells, cytokine environment, and tumor cell intrinsic signaling pathway, and immunotherapy with strong anti-tumor immunity has received more and more research attention due to the limited responsiveness of HCC to ICI monotherapy. There is evidence of an organic combination of radiotherapy, chemotherapy, anti-angiogenic agents and ICI catering to the unmet medical needs of HCC. Moreover, immunotherapies such as adoptive cellular therapy (ACT), cancer vaccines and cytokines also show encouraging efficacy. It can significantly improve the ability of the immune system to eradicate tumor cells. This article reviews the role of immunotherapy in HCC, hoping to improve the effect of immunotherapy and develop personalized treatment regimens.

Synergistic effect of ursodeoxycholic acid on the antitumor activity of sorafenib in hepatocellular carcinoma cells via modulation of STAT3 and ERK

Sorafenib has been approved for the treatment of advanced stage hepatocellular carcinoma but has limited efficacy. Ursodeoxycholic acid exerts cytoprotective activities in hepatocytes and is believed to suppress tumorigenesis through cell cycle arrest and induction of apoptosis. The present study examined whether co-treatment with ursodeoxycholic acid has a synergistic effect on the antitumor activity of sorafenib in hepatocellular carcinoma cells. Notably, co-treatment with both agents more effectively inhibited cell proliferation than sorafenib or ursodeoxycholic acid alone. Furthermore, co-treatment inhibited the phosphorylation of signal transducer and activator of transcription 3 (STAT3) and activated extracellular signal-regulated kinase (ERK), a mitogen-activated protein kinase, accompanied by excessive intracellular reactive oxygen species generation in hepatocellular carcinoma cells. Thus, chemotherapy with sorafenib and ursodeoxycholic combination may be efficacious in hepatocellular carcinoma by inhibiting cell proliferation and inducing apoptosis through reactive oxygen species-dependent activation of ERK and dephosphorylation of STAT3. The present findings may represent a promising therapeutic strategy for patients with advanced hepatocellular carcinoma.

Resveratrol Promoted Interferon-α-Induced Growth Inhibition and Apoptosis of SMMC7721 Cells by Activating the SIRT/STAT1

Interferon-α (IFN-α) resistance is a major hurdle in the treatment of hepatocellular carcinoma (HCC). Signal transducers and activators of transcription 1 (STAT1) play a key role in exerting the antiproliferative and proapoptotic effects of IFN-α on tumors. In this study, we aimed to investigate whether resveratrol can promote IFN-α-induced growth inhibition and the apoptosis on HCC cells through the SIRT/STAT1 pathway. We found that IFN-α induced growth inhibition and apoptosis of SMMC7721 cells, and the effects could be significantly enhanced and blocked by resveratrol and EX527, respectively. Resveratrol not only activated SIRT1 but also induced phosphorylation of STAT1. Further study revealed that ablation of STAT1 reduced the combined antitumor effects of IFN-α and resveratrol, lowered the rate of apoptosis, and improved the viability of SMMC7721 cells. Whereas STAT1 overexpression strengthened the combined antitumor effects of resveratrol and IFN-α. Our findings suggest a novel strategy of using resveratrol to enhance the response of HCC to IFN-α treatment through the SIRT/STAT1 pathway.

ISG15 in the tumorigenesis and treatment of cancer: An emerging role in malignancies of the digestive system

The interferon-stimulated gene 15 ubiquitin-like modifier (ISG15) encodes an IFN-inducible, ubiquitin-like protein. The ISG15 protein forms conjugates with numerous cellular proteins that are involved in a multitude of cellular functions, including interferon-induced immune responses and the regulation of cellular protein turnover. The expression of ISG15 and ISG15-mediated conjugation has been implicated in a wide range of human tumors and cancer cell lines, but the roles of ISG15 in tumorigenesis and responses to anticancer treatments remain largely unknown. In this review, we discuss the findings of recent studies with regard to the role of ISG15 pathways in cancers of the digestive system.

The in vivo antitumor effects of type I-interferon against hepatocellular carcinoma: the suppression of tumor cell growth and angiogenesis

Type I-interferon (IFN) is considered to exert antitumor effects through the inhibition of cancer cell proliferation and angiogenesis. Based on the species-specific biological activity of IFN, we evaluated each antitumor mechanism separately. We further examined the antitumor effects of type I-IFN combined with sorafenib. Human IFN (hIFN) significantly inhibited the proliferation of human hepatocellular carcinoma (HCC) Hep3B cells and the tube formation of human umbilical vein endothelial cells (HUVECs) in vitro. Although mouse IFN (mIFN) did not inhibit the proliferation of Hep3B cells in vitro, mIFN, as well as hIFN, showed significant antitumor effects in mouse Hep3B cell-xenograft model. Furthermore, mIFN treatment amplified the antitumor effects of sorafenib in vivo with the suppression of angiogenesis. The DNA chip analysis showed that the mIFN treatment promoted the antitumor signal pathways of sorafenib, including anti-angiogenic effects. Unlike the effects observed in in vitro experiments, mIFN showed an antitumor effect in the mouse Hep3B cell-xenograft model, suggesting a role of the anti-angiogenic activity in the in vivo tumoricidal effects of type I-IFN. In addition, our findings suggested the clinical utility of combination therapy with type І-IFN and sorafenib for HCC.

Inhibition of STAT3 signaling pathway by ursolic acid suppresses growth of hepatocellular carcinoma

The signal transducer and activator of transcription 3 (STAT3) has been found to be constitutively active in liver cancer. There is no STAT3 inhibitors approved to be used clinically for the treatment or prevention of liver cancer. Some dietary compounds including ursolic acid (UA) have been reported to inhibit the growth of cancer cells. However, whether UA could inhibit STAT3 phosphorylation in hepatocellular carcinoma has not been reported. The inhibitory effects of UA on STAT3 phosphorylation, along with cell viability, migration, colony formation in vitro, as well as tumor growth in vivo were examined in human liver cancer cell lines. Our data showed that UA inhibited the P-STAT3 induced by interleukin-6 (IL-6) in Hep3B liver cancer cells which express very low basal level of P-STAT3. The constitutive STAT3 phosphorylation was also inhibited by UA in HEPG2, 7721 and Huh7 human liver cancer cell lines. UA decreased the expression of downstream target genes of STAT3, such as Bcl-2, Bcl-xl and survivin in general, with difference in these cell lines. UA also suppressed cell viability, cell migration and colony formation in liver cancer cells. Furthermore, UA suppressed STAT3 phosphorylation and HEPG2 tumor growth by oral daily treatment in vivo. UA, which exists widely in fruits and herbs, could inhibit STAT3 activation and the growth of human liver cancer cells in vitro and in vivo. It might be a potential health care product that could be used daily for prevention, as well as a promising candidate for chemotherapy of liver cancer.

A novel engineered interferon-α hybrid molecule increases anticancer efficacy of doxorubicin in breast cancer chemotherapy

Breast cancer is the most common carcinoma among Chinese women. Interferon α (IFNα) has been used to treat various types of cancer, including breast cancer, but its antitumor activity is relative low, which significantly hinders its clinical application. In this study, we utilized a Ph.D.-12 peptide library screening system to identify a short peptide that specifically binds to MCF-7 breast cancer cells. By fusing the MCF-7 binding peptide (MBP) to the C-terminus of IFNα, we constructed an engineered IFNα-MBP fusion molecule (IMBP), and applied this novel fusion protein to the treatment of breast cancer. We found that IMBP exhibited significantly higher activity than wild-type IFNα in inhibiting cell growth and inducing cell apoptosis. Additionally, IMBP potentiated the therapeutic efficacy of doxorubicin-based breast cancer chemotherapy via the activation of cell cycle arrest and cell apoptosis pathway genes including p53, p21, CDK2, cyclin A, caspase 9, Bcl-2 and Bax. The enhanced activity of the synthetic IMBP was also associated with the activation of signal transducer and activation of transcription 1 (STAT1) pathway target genes (STAT1, IFIT1, IFITM1 and MX1). This study evaluated the potential value of the synthetic IMBP as a novel anti-breast cancer agent.

Immunotherapeutic approaches for hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a cancer with a high mortality rate due to the fact that the diagnosis usually occurs at anadvanced stage. Even in case of curative surgical treatment, recurrence is common. Sorafenib and regorafenib are the only therapeutic agents that have been demonstrated to be effective in advanced HCC, thus novel curative approaches are urgently needed. Recent studies focus on the role of immune system in HCC. In fact, the unique immune response in the liver favors tolerance, which can represent a real challenge for conventional immunotherapy in these patients. Spontaneous immune responses against tumor antigens have been detected, and new immune therapies are under investigation: dendritic cell vaccination, immune-modulator strategy, and immune checkpoint inhibition. In recent years different clinical trials examining the use of immunotherapy to treat HCC have been conducted with initial promising results. This review article will summarize the literature data concerning the potential immunotherapeutic approaches in HCC patients.

Synergy with interferon-lambda 3 and sorafenib suppresses hepatocellular carcinoma proliferation

Hepatocellular carcinoma (HCC) is a common and fatal malignancy of the liver. Sorafenib is a small molecule multikinase inhibitor that acts against different cancer cell lines and is used for the treatment of HCC. However, some advanced HCC patients fail to respond to sorafenib, and those who do lack a meaningful clinical benefit. Interferon-lambda 3 (IFN-λ3) is a type III interferon with antiviral, antiproliferative, and immunomodulatory functions. Here, we evaluated the use of IFN-λ3 as an adjuvant treatment with sorafenib in HCC. In the present study, CCK-8 and colony formation assay results showed that treatment with a combination of IFN-λ3 and sorafenib suppresses the viability of HepG2 and SMMC7721 liver cancer cell lines more than treatment with either alone. In addition, flow cytometry results confirmed that treatment with a combination of IFN-λ3 and sorafenib promotes the loss of mitochondrial membrane potential and induces the production of ROS more than treatment with either alone. Furthermore, using a subcutaneous SMMC7721 tumor model, treatment with a combination of IFN-λ3 and sorafenib significantly reduced the tumor growth/volume and induced apoptosis compared to treatment with sorafenib alone. These results show that combined treatment with IFN-λ3 and sorafenib facilitates a synergistic effect on suppressing HCC cancer growth and promoting cell apoptosis in vitro and in vivo. Thus, IFN-λ3 in combination with sorafenib might prove to be a useful adjunctive strategy for the clinical treatment of HCC.

Effects of interferons and double-stranded RNA on human prostate cancer cell apoptosis

Prostate cancer is the second most commonly diagnosed cancer among men in the United States. Prostate cancer therapy is severely hampered by lack of response and development of resistance to conventional chemotherapeutic drugs in patients. Therefore, the development and discovery of new drugs have become an urgent clinical need. Interferons (IFNs), a family of pleiotropic cytokines, exert antitumor activities due to their anti-proliferative, immunomodulatory and proapoptotic functions. Here, we report that pretreatment of prostate cancer PC-3 cells with IFNs sensitized these cells to double-stranded RNAs (dsRNAs)-induced apoptosis. The enhancement effect of IFN treatment was dependent on IFN subtypes, in particular, IFN γ. In comparison with IFN α or β, IFN γ treatment remarkably augmented apoptosis in PC-3 cells induced with polyinosinic:polycytidylic acid (poly I:C), a synthesized form of dsRNA. We demonstrated that IFN-signaling was necessary for these effects by using mutant cell lines. Transfection of 2-5A, the activator of RNase L, or silencing of dsRNA-dependent protein kinase R (PKR) by siRNA did not have any significant impact on this event, suggesting that neither RNase L nor PKR was involved in poly I:C/IFN γ-induced apoptosis in the cells. Further investigation of the apoptotic pathway revealed that Bak, a pro-apoptotic member of the Bcl-2family, was synergistically up-regulated by IFN γ and poly I:C, whereas other members of the family were not affected. Knocking down of Bak demonstrated its contribution to poly I:C/IFN γ-induced apoptosis in the cells. We believeour findings will precipitate the design of novel therapeutic strategies for prostate cancer.

Effects of sorafenib combined with low-dose interferon therapy for advanced hepatocellular carcinoma: a pilot study

BACKGROUND

Sorafenib is a standard of care for advanced hepatocellular carcinoma (HCC). An in vitro study showed the synergistic effects of sorafenib and interferon for HCC. To clarify the efficacy, combination therapy with sorafenib and interferon was performed for patients with advanced HCC.

METHODS

Pegylated interferon α-2a was administered every 2 weeks for the initial 4 weeks. Subsequently, it was combined with sorafenib. We evaluated the anti-tumor effect and biomarkers during treatment period.

RESULTS

The subjects were 13 patients with advanced HCC complicated by hepatitis C virus (HCV)-related liver cirrhosis. A partial response, stable disease and progressive disease were noted in 4, 6, and 3 patients, respectively. The response rate, the disease control rate, the mean time to progression and the median survival time (MST) were 30.8 % (4/13), 76.9 % (10/13), 12.2 months, and 17.5 months, respectively. In 8 Child-Pugh class A and 5 Child-Pugh class B patients, the MST was 22.0 and 11.0 months, respectively (p = 0.001). In plasma vascular endothelial growth factor (VEGF), serum alpha-fetoprotein (AFP), AFP-L3, a protein induced by vitamin K absence or antagonist-II (PIVKA II), and hepatocyte growth factor (HGF), there was no pretreatment factor and no biomarker during the combination therapy to predict therapeutic effect in the present study.

CONCLUSIONS

The results of this study suggest that combination therapy with sorafenib and interferon could be effective and safe in advanced HCC patients with HCV-related liver cirrhosis.

Apoptosis in liver carcinogenesis and chemotherapy

Hepatocellular carcinoma (HCC) is a major health problem. In human hepatocarcinogenesis, the balance between cell death and proliferation is deregulated, tipping the scales for a situation where antiapoptotic signals are overpowering the death-triggering stimuli. HCC cells harbor a wide variety of mutations that alter the regulation of apoptosis and hence the response to chemotherapeutical drugs, making them resistant to the proapoptotic signals. Considering all these modifications found in HCC cells, therapeutic approaches need to be carefully studied in order to specifically target the antiapoptotic signals. This review deals with the recent relevant contributions reporting molecular alterations for HCC that lead to a deregulation of apoptosis, as well as the challenge of death-inducing chemotherapeutics in current HCC treatment.

Immunotherapy for hepatocellular carcinoma: From basic research to clinical use

Hepatocellular carcinoma (HCC) is a common cancer worldwide with a poor prognosis. Few strategies have been proven efficient in HCC treatment, particularly for those patients not indicated for curative resection or transplantation. Immunotherapy has been developed for decades for cancer control and is attaining more attention as a result of encouraging outcomes of new strategies such as chimeric antigen receptor T cells and immune checkpoint blockade. Right at the front of the new era of immunotherapy, we review the immunotherapy in HCC treatment, from basic research to clinical trials, covering anything from immunomodulators, tumor vaccines and adoptive immunotherapy. The mechanisms, efficacy and safety as well as the approach particulars are unveiled to assist readers to gain a concise but extensive understanding of immunotherapy of HCC.

Signal transducer and activator of transcription 4 in liver diseases

STAT4 is a member of the signal transducer and activator of transcription (STAT) family of molecules that localizes to the cytoplasm. STAT4 regulates various genes expression as a transcription factor after it is phosphorylated, dimerizes and translocates to the nucleus. STAT4 activation is detected virtually in the liver of several mouse models of liver injury, as well as the human liver of chronic liver diseases. STAT4 gene polymorphism has been shown to be associated with the antiviral response in chronic hepatitis C and drug-induced liver injury (DILI), primary biliary cirrhosis (PBC), HCV-associated liver fibrosis and in hepatocellular carcinoma (HCC). However, the roles of STAT4 in the pathogeneses of liver diseases are still not understood entirely. This review summarizes the recent advances on the functional roles of STAT4 and its related cytokines in liver diseases, especially in regulating hepatic anti-viral responses, inflammation, proliferation, apoptosis and tumorigenesis. Targeting STAT4 signaling pathway might be a promising strategy in developing therapeutic approaches for treating hepatitis in order to prevent further injury like cirrhosis and liver cancer.

Role of antiviral therapy in reducing recurrence and improving survival in hepatitis B virus-associated hepatocellular carcinoma following curative resection (Review)

Hepatocellular carcinoma (HCC) is one of the major causes of cancer-related mortality worldwide, with the majority of cases associated with persistent hepatitis B virus (HBV) or hepatitis C virus infection. In particular, chronic HBV infection is a predominant risk factor for the development of HCC in Asian and African populations. Hepatic resection, liver transplantion and radiofrequency ablation are increasingly used for the curative treatment of HCC, however, the survival rate of HCC patients who have undergone curative resection remains unsatisfactory due to the high recurrence rate. HCC is a complex disease that is typically resistant to the most commonly used types of chemotherapy and radiotherapy; therefore, the development of novel treatment strategies is required to improve the survival rate of this disease. A high viral load of HBV DNA is the most important correctable risk factor for HCC recurrence, for example nucleos(t)ide analogs improve the outcome following curative resection of HBV-associated HCC, and interferon-α exhibits antitumor activity against various types of cancer via direct inhibitory effects on tumor cells, anti-angiogenesis, enhanced immunogenicity of tumors, immunomodulatory effects and liver dysfunction. In the present review, antiviral treatment for HBV-associated HCC is described as a strategy to reduce recurrence and improve survival.

Purified vitexin compound 1 inhibits growth and angiogenesis through activation of FOXO3a by inactivation of Akt in hepatocellular carcinoma

Vitexins, isolated from the seeds of the Chinese herb Vitex negundo, is known to exert antitumor activity in cancer xenograft models and cell lines. The aim of the current study was to examine whether the Akt/forkhead box protein O3a (FOXO3a) pathway mediates the biological effects of purified vitexin compound 1 (VB-1) in hepatocellular carcinoma (HCC) cells. The effect of VB-1 on the viability of the HCC cell lines HepG2, Hep3B, Huh-7 and the human embryonic liver cells L-02 was investigated using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Growth inhibition was assessed by clonogenic assay, and cell cycle arrest was investigated using flow cytometry. Inhibition of angiogenesis was evaluated using a matrigel in vitro HUVEC tube formation assay. The effects on the Akt/FOXO3a pathway were detected by western blotting. VB-1 suppressed the proliferation of HepG2, Hep3B, Huh-7 cells, but had little effect on L-02 cells. VB-1 inhibited anchorage-dependent and -independent HepG2 cell growth in a concentration-dependent manner by induction of cell cycle arrest at G1/G0. VB-1 also reduced the secretion of vascular endothelial growth factor (VEGF), resulting in the inhibition of endothelial tube formation. Phosphorylated Akt and its downstream effector FOXO3a were downregulated in VB-1-treated HepG2 cells. Knockdown of Akt1 by small interfering RNA (siRNA) enhanced growth inhibition, and silencing FOXO3a by siRNA attenuated this action. VB-1 inhibited growth and induced cell cycle arrest at G1/G0 by regulating the Akt/FOXO3a pathway. The findings suggested that VB-1 is a potentially promising candidate for the treatment of HCC.

Synergistic antitumour activity of sorafenib in combination with tetrandrine is mediated by reactive oxygen species (ROS)/Akt signaling

BACKGROUND

Sorafenib is a potent inhibitor against Raf kinase and several receptor tyrosine kinases that has been approved for the clinical treatment of advanced renal and liver cancer. Combining sorafenib with other agents has been shown to improve its antitumour efficacy by not only reducing the toxic side effects but also preventing primary and acquired resistance to sorafenib. We have previously observed that tetrandrine exhibits potent antitumour effects in human hepatocellular carcinoma. In this study, we investigated the synergistic antitumour activity of sorafenib in combination with tetrandrine.

METHODS

This was a two-part investigation that included the in vitro effects of sorafenib in combination with tetrandrine on cancer cells and the in vivo antitumour efficacy of this drug combination on tumour xenografts in nude mice.

RESULTS

Combined treatment showed a good synergistic antitumour effect yet spared non-tumourigenic cells. The potential molecular mechanism may be mainly that it activated mitochondrial death pathway and induced caspase-dependent apoptosis in the cancer cells. Accumulation of intracellular reactive oxygen species (ROS) and subsequent activation of Akt may also be involved in apoptosis induction.

CONCLUSION

The antitumour activity of sorafenib plus tetrandrine may be attributed to the induction of the intrinsic apoptosis pathway through ROS/Akt signaling. This finding provides a novel approach that may broaden the clinical application of sorafenib.

Antiproliferative effects of sorafenib and pegylated IFN‑α2b on human liver cancer cells in vitro and in vivo

Novel therapeutic strategies are needed to treat patients with advanced hepatocellular carcinoma (HCC). Combination therapy of sorafenib and type I interferon (IFN) has substantial activity in patients with metastatic renal cell carcinoma. We investigated the antiproliferative effects of sorafenib in combination with pegylated interferon-α2b (PEG-IFN-α2b) on human hepatocellular carcinoma (HCC) cells in vitro and in vivo. A poorly differentiated HCC cell line derived from a patient with hepatitis C virus infection, HAK-1B and the moderately differentiated HCC cell line KIM-1 were used in this study. We demonstrated a synergistic antiproli ferative effect of combination therapy on HAK-1B cells in vitro. In the in vivo study, a significant reduction of tumor volume and weight were observed in the combination group in both HAK-1B and KIM1 tumors, although synergistic effects were not clearly observed. The density of CD34-positive microvessels was significantly lower and cleaved caspase-3-positive apoptotic cell numbers were higher, in the sorafenib group and the combination group compared to the control or PEG-IFN-α2b group in both HAK-1B and KIM-1 tumors. Ki67 labeling index was significantly lower in the combination group compared to the control group in KIM-1 tumors. In conclusion, our results suggest that the combination therapy may be more effective for the treatment of HCC cases with variable sensitivity to antitumor effects of single therapy with either sorafenib or PEG-IFN-α2b.

PTK787/ZK222584 combined with interferon alpha and 5-fluorouracil synergistically inhibits VEGF signaling pathway in hepatocellular carcinoma

BACKGROUND

The prognosis of patients with hepatocellular carcinoma (HCC) and portal vein tumor thrombus remains poor. We previously reported the beneficial effects of interferon alpha (IFN) and 5-fluorouracil (5-FU) combination therapy for these patients. We showed that the mechanism of therapy was regulation of vascular endothelial growth factor (VEGF). Here, we combined IFN/5-FU therapy with the VEGF receptor-selective inhibitor PTK787/ZK222584 (PTK/ZK) and examined the antitumor effects and the mechanism of action.

METHODS

We studied two HCC cell lines, PLC/PRF/5 and HuH7, and a human umbilical vein endothelial cell line, HUVEC. We studied the effects of IFN/5-FU with or without PTK/ZK in growth inhibition assays, immunohistochemistry, Western blot analysis, and immunocytochemistry.

RESULTS

In a HuH7 xenograft model, the combination of PTK/ZK and IFN/5-FU significantly inhibited proliferation, induced apoptosis, decreased microvessel density, reduced the number of tumor cells that expressed VEGF receptor 2 (VEGFR-2), and repressed the phosphorylation of Akt in vivo. In HCC cells and HUVECs in vitro, IFN/5-FU plus PTK/ZK repressed the expression of VEGFR-2 and repressed the phosphorylation of VEGFR, Akt, Erk, and p38MAPK.

CONCLUSIONS

VEGF signaling inhibition enhanced the antitumor effects of IFN/5-FU therapy on HCC cells and endothelial cells via Erk, Akt, and p38MAPK pathways.

Role of sorafenib in the treatment of advanced hepatocellular carcinoma: An update

Sorafenib is the first and only p.o. administrated drug currently approved to treat advanced hepatocellular carcinoma (HCC). However, concerns have been raised about sorafenib therapy, including acquired drug resistance. This review provides an overview of sorafenib in the treatment of HCC on the basis of data obtained in the laboratory and in clinical studies. Three underlying mechanisms have been found to support sorafenib therapy. First, sorafenib blocks HCC cell proliferation by inhibiting BRaf and Raf1/c-Raf serine/threonine kinase phosphorylation in the mitogen-activated protein kinase pathway. Second, sorafenib induces apoptosis by reducing elF4E phosphorylation and downregulating Mcl-1 levels in tumor cells. Third, sorafenib prevents tumor-associated angiogenesis by inactivating vascular endothelial growth factor receptors (VEGFR-2 and -3) and the platelet-derived growth factor receptor-β. Clinical trials have demonstrated the effectiveness and relative safety of sorafenib, and thus the drug is used in unresectable HCC. However, many patients may develop acquired resistance to sorafenib, so their response to sorafenib is eventually lost. Sorafenib may induce autophagy, which leads to apoptosis. However, autophagy can also cause drug resistance. Many studies have combined sorafenib with other treatments in an effort to increase its effects, reduce the necessary dose or overcome resistance. It is urgent to study the mechanisms underlying how sorafenib interacts with cellular molecules and other drugs to increase its efficacy and reduce resistance in HCC patients.

Role of sorafenib in the treatment of advanced hepatocellular carcinoma: An update

Sorafenib is the first and only p.o. administrated drug currently approved to treat advanced hepatocellular carcinoma (HCC). However, concerns have been raised about sorafenib therapy, including acquired drug resistance. This review provides an overview of sorafenib in the treatment of HCC on the basis of data obtained in the laboratory and in clinical studies. Three underlying mechanisms have been found to support sorafenib therapy. First, sorafenib blocks HCC cell proliferation by inhibiting BRaf and Raf1/c-Raf serine/threonine kinase phosphorylation in the mitogen-activated protein kinase pathway. Second, sorafenib induces apoptosis by reducing elF4E phosphorylation and downregulating Mcl-1 levels in tumor cells. Third, sorafenib prevents tumor-associated angiogenesis by inactivating vascular endothelial growth factor receptors (VEGFR-2 and -3) and the platelet-derived growth factor receptor-β. Clinical trials have demonstrated the effectiveness and relative safety of sorafenib, and thus the drug is used in unresectable HCC. However, many patients may develop acquired resistance to sorafenib, so their response to sorafenib is eventually lost. Sorafenib may induce autophagy, which leads to apoptosis. However, autophagy can also cause drug resistance. Many studies have combined sorafenib with other treatments in an effort to increase its effects, reduce the necessary dose or overcome resistance. It is urgent to study the mechanisms underlying how sorafenib interacts with cellular molecules and other drugs to increase its efficacy and reduce resistance in HCC patients.