Antitumor effects of a combination of interferon-alpha and sorafenib on human renal carcinoma cell lines

Speckle-type POZ protein could play a potential inhibitory role in human renal cell carcinoma

BACKGROUND

Speckle-type POZ protein(SPOP), a substrate adaptor of Cul3 ubiquitin ligase, plays crucial roles in solid neoplasms by promoting the ubiquitination and degradation of substrates. Limited studies have shown that SPOP is overexpressed in human renal cell carcinoma (RCC) tissue. However, the exact role of SPOP in RCC remains unclear and needs to be further elucidated. The present study showed that SPOP was expressed at different levels in different RCC cell lines. The purpose of this study was to explore the roles of SPOP in the biological features of RCC cells and the expression levels of SPOP in human tissue microarray (TMA) and kidney tissues.

METHODS

Here, SPOP was overexpressed by lentiviral vector transfection in ACHN and Caki-1 cells, and SPOP was knocked down in Caki-2 cells with similar transfection methods. The transfection efficiency was evaluated by quantitative PCR and western blotting analyses. The role of SPOP in the proliferation, migration, invasion and apoptosis of cell lines was determined by the MTT, wound-healing, transwell and flow cytometry assays. Moreover, the cells were treated with different drug concentrations in proliferation and apoptosis assays to investigate the effect of sunitinib and IFN-α2b on the proliferation and apoptosis of SPOP-overexpressing cells and SPOP-knockdown RCC cells. Finally, immunohistochemical staining of SPOP was performed in kidney tissues and TMAs, which included RCC tissues and corresponding adjacent normal tissues.

RESULTS

Overexpression of SPOP inhibited cell proliferation, migration and invasion and increased cell apoptosis. Interestingly, sunitinib and IFN-α2b at several concentrations increased the proliferation inhibitory rate and total apoptosis rate of cells overexpressing SPOP. The findings of the present study showed that the SPOP protein was significantly expressed at low levels in most clear cell RCC (ccRCC) tissues and at relatively high levels in the majority of adjacent normal tissues and kidney tissues. Kaplan-Meier survival analysis showed that there was no statistically significant difference in cumulative survival based on the data of different SPOP expression levels in TMA and patients.

CONCLUSIONS

In contrast to previous studies, our findings demonstrated that overexpression of SPOP might suppress the progression of RCC cells, which was supported by cell experiments and immunohistochemical staining. SPOP could be a potential tumour inhibitor in RCC.

Drug resistance in papillary RCC: from putative mechanisms to clinical practicalities

Papillary renal cell carcinoma (pRCC) is the second most common renal cell carcinoma (RCC) subtype and accounts for 10-15% of all RCCs. Despite clinical need, few pharmacogenomics studies in pRCC have been performed. Moreover, current research fails to adequately include pRCC laboratory models, such as the ACHN or Caki-2 pRCC cell lines. The molecular mechanisms involved in pRCC development and drug resistance are more diverse than in clear-cell RCC, in which inactivation of VHL occurs in the majority of tumours. Drug resistance to multiple therapies in pRCC occurs via genetic alteration (such as mutations resulting in abnormal receptor tyrosine kinase activation or RALBP1 inhibition), dysregulation of signalling pathways (such as GSK3β-EIF4EBP1, PI3K-AKT and the MAPK or interleukin signalling pathways), deregulation of cellular processes (such as resistance to apoptosis or epithelial-to-mesenchymal transition) and interactions between the cell and its environment (for example, through activation of matrix metalloproteinases). Improved understanding of resistance mechanisms will facilitate drug discovery and provide new effective therapies. Further studies on novel resistance biomarkers are needed to improve patient prognosis and stratification as well as drug development.

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.

Choosing the right cell line for renal cell cancer research

Cell lines are still a tool of choice for many fields of biomedical research, including oncology. Although cancer is a very complex disease, many discoveries have been made using monocultures of established cell lines. Therefore, the proper use of in vitro models is crucial to enhance our understanding of cancer. Therapeutics against renal cell cancer (RCC) are also screened with the use of cell lines. Multiple RCC in vitro cultures are available, allowing in vivo heterogeneity in the laboratory, but at the same time, these can be a source of errors. In this review, we tried to sum up the data on the RCC cell lines used currently. An increasing amount of data on RCC shed new light on the molecular background of the disease; however, it revealed how much still needs to be done. As new types of RCC are being distinguished, novel cell lines and the re-exploration of old ones seems to be indispensable to create effective in vitro tools for drug screening and more.

Growth inhibitory effect of an injectable hyaluronic acid-tyramine hydrogels incorporating human natural interferon-α and sorafenib on renal cell carcinoma cells

Immunotherapy including interferon-alpha (IFN-α) is one of the treatment options for metastatic renal cell carcinoma (mRCC) patients. Despite clinical benefits for the selected patients, IFN-α therapy has some problems, such as poor tolerability and dose-limiting adverse effects. In addition, the frequent injections reduce a patient's quality of life and compliance. Recently, an injectable and biodegradable hydrogel system to prolong drug release is reported. In this study, we investigated the anticancer effect of IFN-α (Sumiferon®)-incorporated hyaluronic acid-tyramine (HA-Tyr) hydrogels in human RCC-xenografted in nude mice. We also evaluated the synergistic efficacy of IFN-α-incorporated HA-Tyr hydrogels+sorafenib in this model. IFN-α-incorporated HA-Tyr hydrogels+sorafenib most effectively inhibited tumor growth on human RCC cells xenografted in nude mice. In addition, IFN-α-incorporated HA-Tyr hydrogels+sorafenib inhibited the proliferation of tumor in nude mice by inducing apoptosis and the suppression of angiogenesis. Our results suggest a possibility that HA-Tyr hydrogel drug delivery system prolongs the biological half-life of natural human IFN-α and enhances its anticancer effects on human RCC cells.

STATEMENT OF SIGNIFICANCE

The scope of this study is to provide an alternative approach to improve the anticancer efficacy in renal cell carcinoma (RCC) treatment by using hyaluronic acid-tyramine (HA-Tyr) hydrogel drug delivery system. We investigated the anticancer effect of natural interferon-α (IFN-α)-incorporated HA-Tyr hydrogels in RCC cells. We also evaluated the synergistic efficacy of natural human IFN-α-incorporated HA-Tyr hydrogels+sorafenib. We demonstrated that HA-Tyr hydrogel system is able to release natural human IFN-α in sustained manner and enhances its anticancer effects on human RCC cells. In addition, we suggested that IFN-α-incorporated HA-Tyr hydrogels+sorafenib exhibited most effectively anticancer effects. Hence, we believe that this approach could be applied to treatment with RCC in the future.

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.

Effects of hypoxia on human cancer cell line chemosensitivity

Background

Environment inside even a small tumor is characterized by total (anoxia) or partial oxygen deprivation, (hypoxia). It has been shown that radiotherapy and some conventional chemotherapies may be less effective in hypoxia, and therefore it is important to investigate how different drugs act in different microenvironments. In this study we perform a large screening of the effects of 19 clinically used or experimental chemotherapeutic drugs on five different cell lines in conditions of normoxia, hypoxia and anoxia.

Methods

A panel of 19 commercially available drugs: 5-fluorouracil, acriflavine, bortezomib, cisplatin, digitoxin, digoxin, docetaxel, doxorubicin, etoposide, gemcitabine, irinotecan, melphalan, mitomycin c, rapamycin, sorafenib, thalidomide, tirapazamine, topotecan and vincristine were tested for cytotoxic activity on the cancer cell lines A2780 (ovarian), ACHN (renal), MCF-7 (breast), H69 (SCLC) and U-937 (lymphoma). Parallel aliquots of the cells were grown at different oxygen pressures and after 72 hours of drug exposure viability was measured with the fluorometric microculture cytotoxicity assay (FMCA).

Results

Sorafenib, irinotecan and docetaxel were in general more effective in an oxygenated environment, while cisplatin, mitomycin c and tirapazamine were more effective in a low oxygen environment. Surprisingly, hypoxia in H69 and MCF-7 cells mostly rendered higher drug sensitivity. In contrast ACHN appeared more sensitive to hypoxia, giving slower proliferating cells, and consequently, was more resistant to most drugs.

Conclusions

A panel of standard cytotoxic agents was tested against five different human cancer cell lines cultivated at normoxic, hypoxic and anoxic conditions. Results show that impaired chemosensitivity is not universal, in contrast different cell lines behave different and some drugs appear even less effective in normoxia than hypoxia.

Recent advances in the treatment of metastatic renal cell carcinoma

In the past 5 years, the treatment of patients with metastatic renal cell carcinoma has changed dramatically from being largely cytokine-based with the emergence of targeted therapy. Following the elucidation of various molecular pathways in renal cell carcinoma, targeted agents (particularly vascular endothelial growth factor-targeting antiangiogenic agents) now form the backbone of most therapeutic strategies for patients with metastatic renal cell carcinoma and the outcome of treatment has improved. However, many tumors eventually develop resistance to targeted therapy due to secondary mutation of the target protein or compensatory changes within the target pathway that bypass the site of inhibition. On the other hand, there are new forms of immunotherapy that hold the promise of improving the outcome for patients with metastatic renal cell carcinoma. In this article, we describe some of these new therapies, including the anti-vascular endothelial growth factor monoclonal antibody bevacizumab, several receptor tyrosine kinase inhibitors (sorafenib, sunitinib, pazopanib, axitinib, and tivozanib), the mammalian target of rapamycin inhibitors temsirolimus and everolimus, and new immunotherapy modalities, such as anti-cytotoxic T-lymphocyte-associated antigen 4 antibody and anti-programmed cell death 1/programmed cell death-ligand 1 antibody. We also discuss their role in the current management of patients with metastatic renal cell carcinoma.

Targeting the endothelin axis with atrasentan, in combination with IFN-alpha, in metastatic renal cell carcinoma

Background:

The endothelin system is involved in tumour growth. Atrasentan, a selective endothelin-A-receptor antagonist, blocks endothelin signalling. This phase I trial studied combining treatment of interferon-alpha (IFN-α) with atrasentan in renal cell carcinoma (RCC).

Patients and methods:

This study evaluated the safety and tolerance of IFN-α (9MU subcutaneously (s.c.) three times a week) in combination with atrasentan (2.5, 5 and 10 mg orally once daily) in untreated metastatic RCC. Cohort 10 mg was extended to obtain insights in efficacy and pharmacodynamics.

Results:

Observed toxicities mainly consisted of known IFN-like toxicities (anorexia, chills, fever, fatigue and nausea), and of nasal congestion (associated to atrasentan). None of these toxicities were considered dose limiting. Cohort 10 mg was extended up to 32 patients; in a subset of patients treated according to the protocol (n=27), median overall survival (OS) was 17.3 months. One patient (3.1%) showed a partial response lasting 14.3 months. In an exploratory analysis, we observed that in the subset of patients with declining vascular endothelial growth factor (VEGF) levels (in combination with rising Endothelin-1 levels), median OS was 22.2 months compared with 2.2 months in patients with increasing VEGF levels.

Conclusion:

Combination treatment of IFN-α 9MU-α s.c. three times a week and atrasentan 10 mg once daily is tolerated. Clinical activity, especially OS, and biomarkers in our view warrant further studies targeting the endothelin axis.

Serum interferon alpha receptor 2 mRNA may predict efficacy of interferon alpha with/without low-dose sorafenib for metastatic clear cell renal cell carcinoma

Background

Interferon (IFN) alpha is one of the central agents in immunotherapy for renal cell carcinoma (RCC). It acts by binding to the IFN-alpha receptor (IFNAR). We previously reported that increased tumor expression of IFNAR2 mRNA was associated with the metastatic potential and progression of RCC, as well as with a poor response of metastatic RCC to IFN-alpha therapy. This study investigated the influence of serum IFNAR2 in RCC patients.

Methods

We measured serum IFNAR2 mRNA levels and quantified IFNAR mRNA expression in paired tumor and non-tumor tissues from the surgical specimens of 66 consecutive RCC patients by the real-time reverse transcription polymerase chain reaction (RT-PCR). We also measured phosphorylated Akt (Ser-473) and phosphorylated-S6 ribosomal protein (Ser-235/236) proteins levels in paired tumor and non-tumor tissues of patients with metastatic RCC by Western blotting.

Results

The serum level of IFNAR2 mRNA was not associated with its tumor tissue level. Serum IFNAR2 mRNA was positively correlated with tumor size (P < 0.05), but not with tumor grade, pT stage, metastasis, microscopic vascular invasion, or serum C-reactive protein. Serum levels of IFNAR2 mRNA were significantly higher in patients with a good response to IFN-alpha ± sorafenib than in those with a poor response (P < 0.0001). Tumor tissue IFNAR2 mRNA levels and phosphorylated-S6 ribosomal protein (Ser-235/236) levels were associated with metastatic potential (P < 0.001 and P < 0.01, respectively), and patients with a low IFNAR2 mRNA level and low phosphorylated Akt (Ser-473) protein level in the primary tumor showed a good response to IFN-α ± sorafenib (IFN-α ± Sor: CR-PR) (P < 0.01 and P < 0.05, respectively). Kaplan–Meier survival analysis showed that a higher serum IFNAR2 mRNA level was associated with longer overall survival of treated patients (P < 0.05), while a higher tumor tissue IFNAR2 mRNA level was related to shorter overall survival (P < 0.01).

Conclusions

Our findings suggest that a high serum level of IFNAR2 mRNA may be a useful marker for predicting the response of metastatic RCC to IFN-alpha ± sorafenib therapy.

Mechanism of synergistic antitumor effect of sorafenib and interferon-α on treatment of renal cell carcinoma

PURPOSE

The multikinase and tyrosine kinase inhibitor sorafenib has antitumor activity in patients with advanced renal cell carcinoma. Recent reports show the ability of sorafenib to synergize with interferon-α, leading to greater antitumor activity. We examined the underlying mechanism of sorafenib and interferon-α synergism for renal cell carcinoma treatment in vitro and in tumor bearing murine models.

MATERIALS AND METHODS

We used murine and human renal cell carcinoma cell lines for in vitro cell proliferation assay. ACHN (ATCC®) and RENCA tumors were subcutaneously transplanted into NCr-nu/nu and syngeneic BALB/c mice (Charles River Laboratories, Yokohama, Japan), respectively. Mice were treated with sorafenib and/or interferon-α, and tumor growth was monitored. Immunological assays were done in the RENCA model.

RESULTS

In the ACHN and RENCA cell lines combination index analysis clearly revealed the synergistic antiproliferative effects of interferon-α and sorafenib in vitro. In the ACHN NCr-nu/nu model we clearly noted the synergistic antitumor effects of interferon-α and sorafenib, indicating the synergistic direct effects of each drug on tumor growth. In the RENCA BALB/c model flow cytometry showed no change in the proportion of lymphocytes. However, while sorafenib alone did not induce natural killer or cytotoxic T-lymphocyte activity against RENCA in that model, interferon-α alone or combined with sorafenib induced natural killer and cytotoxic T-lymphocyte activity.

CONCLUSIONS

Our results show the synergistic activity of interferon-α and sorafenib. These findings provided the rationale for combination therapy with interferon-α and sorafenib in patients with advanced renal cell carcinoma.

Poor cytokine-induced phosphorylation in chronic myeloid leukemia patients at diagnosis is effectively reversed by tyrosine kinase inhibitor therapy

OBJECTIVE

In chronic myeloid leukemia (CML), uncontrolled tyrosine kinase activity of the BCR-ABL1 oncoprotein results in aberrant signaling pathways and increased cell proliferation. Acquired immune tolerance to leukemic antigens further enables tumor cell expansion. Tyrosine kinase inhibitor (TKI) therapy interferes with the immunoregulatory system by targeting off-target kinases both in malignant and nonmalignant cells. The aim of this study was to analyze the immune cell function by phosphoprotein profiling in CML patients.

MATERIALS AND METHODS

Blood samples from diagnostic phase and TKI-treated patients were analyzed by multicolor phosphoprotein flow cytometry enabling measurements at the single-cell level. Both unstimulated baseline activation status and cytokine-induced responses were evaluated.

RESULTS

In diagnostic-phase and imatinib-treated patients, the baseline phosphoprotein activation status was similar to healthy controls. In dasatinib-treated patients, basal phosphoprotein levels were slightly decreased; in particular, the signal transduction and activator of transcription protein 3 pathway was affected in both myeloid and lymphoid cells. The activation responses to various cytokines, granulocyte-macrophage colony-stimulating factor in particular were significantly suppressed in untreated CML patients. During imatinib and dasatinib therapy, the aberrantly suppressed phosphorylation responses were normalized.

CONCLUSIONS

Cytokine responses are hampered in untreated CML patients, which may have an effect on various immunological processes in vivo. Interestingly, during TKI treatment, phosphorylation responses were normal, suggesting that TKI treatment does not alter the reactivity of healthy immune effector cells. However, dasatinib treatment was associated with diminished basal activation of the immunosuppressive signal transduction and activator of transcription protein 3 signaling pathway, which could have clinical significance in reversing the lymphocyte anergy against tumor cells.

Synergistic combinations of signaling pathway inhibitors: mechanisms for improved cancer therapy

Cancer cells contain multiple signal transduction pathways whose activities are frequently elevated due to their transformation, and that are often activated following exposure to established cytotoxic therapies including ionizing radiation and chemical DNA damaging agents. Many pathways activated in response to transformation or toxic stresses promote cell growth and invasion and counteract the processes of cell death. As a result of these findings many drugs, predominantly protein and lipid kinase inhibitors, of varying specificities, have been developed to block signaling by cell survival pathways in the hope of killing tumor cells and sensitizing them to toxic therapies. Unfortunately, due to the plasticity of signaling processes within a tumor cell, inhibition of any one growth factor receptor or signaling pathway frequently has only modest long-term effects on cancer cell viability, tumor growth, and patient survival. As a result of this realization, a greater emphasis has begun to be placed on rational combinations of drugs that simultaneously inhibit multiple inter-linked signal transduction/survival pathways. This, it is hoped, will limit the ability of tumor cells to adapt and survive because the activity within multiple parallel survival signaling pathways has been reduced. This review will discuss some of the approaches that have been taken to combine signal transduction modulatory agents to achieve enhanced tumor cell killing.