Defective Jak-Stat activation in renal cell carcinoma is associated with interferon-alpha resistance

Ceragenins exhibit antiviral activity against SARS-CoV-2 by increasing the expression and release of type I interferons upon activation of the host's immune response

The COVID-19 pandemic caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) heavily burdened the entire world socially and economically. Despite a generation of vaccines and therapeutics to confront infection, it remains a threat. Most available antivirals target viral proteins and block their activity or function. While such an approach is considered effective and safe, finding treatments for specific viruses of concern leaves us unprepared for developed resistance and future viral pandemics of unknown origin. Here, we propose ceragenins (CSAs), synthetic amphipathic molecules designed to mimic the properties of cationic antimicrobial peptides (cAMPs), as potential broad-spectrum antivirals. We show that selected CSAs exhibit antiviral activity against SARS-CoV-2 and low-pathogenic human coronaviruses 229E, OC43, and NL63. The mechanism of action of CSAs against coronaviruses is mainly attributed to the stimulation of antiviral cytokines, such as type I interferons or IL-6. Our study provides insight into a novel immunomodulatory strategy that might play an essential role during the current pandemic and future outbreaks.

Primate hemorrhagic fever-causing arteriviruses are poised for spillover to humans

Simian arteriviruses are endemic in some African primates and can cause fatal hemorrhagic fevers when they cross into primate hosts of new species. We find that CD163 acts as an intracellular receptor for simian hemorrhagic fever virus (SHFV; a simian arterivirus), a rare mode of virus entry that is shared with other hemorrhagic fever-causing viruses (e.g., Ebola and Lassa viruses). Further, SHFV enters and replicates in human monocytes, indicating full functionality of all of the human cellular proteins required for viral replication. Thus, simian arteriviruses in nature may not require major adaptations to the human host. Given that at least three distinct simian arteriviruses have caused fatal infections in captive macaques after host-switching, and that humans are immunologically naive to this family of viruses, development of serology tests for human surveillance should be a priority.

Prognostic value and immunological role of AXL gene in clear cell renal cell carcinoma associated with identifying LncRNA/RBP/AXL mRNA networks

Backgrounds

This article aimed to explore the prognostic and immunological roles of AXL gene in clear cell renal cell carcinoma (ccRCC) for overall survival (OS) and to identify the LncRNA/RBP/AXL mRNA networks.

Methods

AXL-related gene expression matrix and clinical data were obtained from The Cancer Genome Atlas (TCGA) dataset and AXL-related pathways were identified by gene set enrichment analysis (GSEA). We performed univariate/multivariate Cox regression analysis to evaluate independent prognostic factors and the relationships between AXL and immunity were also investigated.

Results

The outcomes of us indicated that the AXL mRNA expression was up-regulated in ccRCC samples and high expression of AXL was associated with worse OS in TCGA dataset (P < 0.01). Further external verification results from HPA, UALCAN, ICGC dataset, GSE6344, GSE14994, and qRT-PCR remained consistent (all P < 0.05). AXL was also identified as an independent prognostic factor for ccRCC by univariate/multivariate Cox regression analysis (both P < 0.05). A nomogram including AXL expression and clinicopathological factors was established by us and GSEA results found that elevated AXL expression was associated with the JAK-STAT, P53, WNT, VEGF and MAPK signaling pathways. In terms of immunity, AXL was dramatically linked to tumor microenvironment, immune cells, immune infiltration, immune checkpoint molecules and tumor mutational burden (TMB). As for its potential mechanisms, we also identified several LncRNA/RBP/AXL mRNA axes.

Conclusions

AXL was revealed to play prognostic and immunological roles in ccRCC and LncRNA/RBP/AXL mRNA axes were also identified by us for its potential mechanisms.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12935-021-02322-y.

Emerging Role of Neuropilin-1 and Angiotensin-Converting Enzyme-2 in Renal Carcinoma-Associated COVID-19 Pathogenesis

Neuropilin-1 (NRP1) is a recently identified glycoprotein that is an important host factor for SARS-CoV-2 infection. On the other hand, angiotensin-converting enzyme-2 (ACE2) acts as a receptor for SARS-CoV-2. Additionally, both NRP1 and ACE2 express in the kidney and are associated with various renal diseases, including renal carcinoma. Therefore, the expression profiles of NRP1 and ACE2 in kidney renal clear cell carcinoma (KIRC) and kidney renal papillary cell carcinoma (KIRP) patients from the various cancer databases were investigated along with their impact on patients’ survivability. In addition, coexpression analysis of genes involved in COVID-19, KIRC, and KIRP concerning NRP1 and ACE2 was performed. The results demonstrated that both t NRP1 and ACE2 expressions are upregulated in KIRC and KIRP compared to healthy conditions and are significantly correlated with the survivability rate of KIRC patients. A total of 128 COVID-19-associated genes are coexpressed, which are positively associated with NRP1 and ACE2 both in KIRC and KIRP. Therefore, it might be suggested that, along with the ACE2, high expression of the newly identified host factor NRP1 in renal carcinomas may play a vital role in the increased risk of SARS-CoV-2 infection and survivability of COVID-19 patients suffering from kidney cancers. The findings of this investigation will be helpful for further molecular studies and prevention and/or treatment strategies for COVID-19 patients associated with renal carcinomas.

UBA2 promotes the progression of renal cell carcinoma by suppressing the p53 signaling

BACKGROUND

Renal cell carcinoma or RCC is a type of malignancy commonly occurred in the human kidney especially in the adults. The pathogenesis of RCC involves the complex networking of multiple signaling pathways, and the underlying molecular mechanisms remain largely unclear.

OBJECTIVES

This study aimed to elucidate the regulatory functions of UBA2 and explore its potential downstream molecules during the tumor progression in RCC.

METHODS

In this paper, the expression of UBA2 and associated molecules was examined by RT-qPCR and western blotting. The proliferative activity of RCC cells was determined using CCK-8 assay and immunofluorescence staining of proliferation-related marker Ki-67. Moreover, the cell distribution and apoptosis were evaluated by flow cytometry.

RESULTS

Our results revealed the upregulation of UBA2 in RCC tissues and cells, and the high-expression of UBA2 was also associated with bigger tumor size, more advanced stage, and poorer overall survival in RCC patients. In addition, UBA2 knockdown was able to suppress the growth of RCC cells and induced cell cycle arrest at G0/G1 phase. Furthermore, the p53 signaling could be the novel target of UBA2 in RCC, and UBA2 affected the biological behaviors of RCC cells in a p53-dependent manner.

CONCLUSION

In summary, UBA2 was able to enhance the proliferation, inhibit the apoptosis, and suppress cell cycle arrest in RCC cells by targeting the p53 pathway.

Antibody-Based Targeting of Interferon-Beta-1a Mutein in HER2-Positive Cancer Enhances Antitumor Effects Through Immune Responses and Direct Cell Killing

Type I interferon (IFN) has been approved as an anticancer agent to treat some malignancies. However, IFNs have a short in vivo half-life, systemic toxicity, and poor biophysical properties, which prevent it from being widely used for cancer therapy. This study aimed to construct recombinant IFN-β-1a mutein immunocytokines that comprise a human epidermal growth factor receptor 2 (HER2)-targeting antibody and IFN-β muteins with an additional glycosylation, which can overcome the limitation of the cytokine itself. Hence, the molecular design aims to 1) enhance productivity and biophysical properties by adding secondary glycosylation in IFN-β, 2) increase the therapeutic index of IFN-β therapy by preferential retention at the tumor by possessing high affinity for HER2-expressing cancer cells, and 3) improve the pharmacokinetics and, thus, the convenience of IFN-β administration. The yield of trastuzumab-IFN-β mutein was higher than that of trastuzumab-wild-type IFN-β in the mammalian cell culture system. Trastuzumab-IFN-β mutein showed similar IFN activity and HER2-targeting ability equivalent to that of IFN-β mutein and trastuzumab, respectively. Trastuzumab-IFN-β mutein directly inhibited the growth of HER2-positive gastric cancer cell lines and was more effective than trastuzumab or IFN-β mutein alone. Trastuzumab-IFN-β mutein and IFN-β mutein displayed enhanced immune cell-mediated cytotoxicity. Collectively, trastuzumab-IFN-β mutein may have indirect immune cell-mediated antitumor effects and direct cell growth inhibitory effects. Tumor-targeting effect of trastuzumab-IFN-β mutein was analyzed using in vivo fluorescence imaging. The accumulation of trastuzumab-IFN-β mutein was observed in HER2-positive tumors rather than other tissues except the liver. To evaluate the both direct tumor growth inhibition effect and indirect immune cell-mediated antitumor effect, we tested the effect of trastuzumab-IFN-β mutein in HER2-positive cancer xenograft models using nude mice or humanized mice. Trastuzumab-IFN-β mutein could significantly enhance tumor regression when compared with trastuzumab or IFN-β mutein. In addition, an increase in tumor-infiltrating lymphocytes was observed in the trastuzumab-IFN-β mutein-treated group, implying that the tumor-targeting IFN-β may have an enhanced antitumor effect through increased immune response. Therefore, targeting IFN-β with an anti-HER2 monoclonal antibody makes the immunocytokine more potent than either agent alone. These novel findings suggest that trastuzumab-IFN-β mutein merits clinical evaluation as a new candidate of anticancer therapeutics.

Overexpression of chemokine receptor lymphotactin receptor 1 has prognostic value in clear cell renal cell carcinoma

Background

Clear cell renal cell carcinoma (ccRCC) is an aggressive subtype of renal cell carcinoma. X‐C motif chemokine receptor 1 (XCR1) exerts important roles in tumor progression; however, its role in ccRCC is unclear.

Methods

We utilized publicly available data from The Cancer Genome Atlas (TCGA) to assess the role of XCR1 in ccRCC and validated the results in 36 samples from patients with ccRCC who underwent curative resection in Xinqiao Hospital Chongqing. XCR1 overexpression was identified in ccRCC, which was confirmed by qRT‐PCR assay and immunohistochemical staining of ccRCC samples.

Results

For the TCGA and clinical data, Kaplan–Meier survival analysis revealed that higher XCR1 expression in ccRCC was related to longer overall survival. Cox regression analysis suggested that XCR1 is an independent risk factor for ccRCC. GSEA analysis suggested that XCR1 is associated with the JAK/STAT signaling pathway. XCR1 knockdown by small interfering RNA (siRNA) significantly increased ccRCC cell proliferation and migration, and decreased cell apoptosis.

Conclusion

We found higher XCR1 expression in ccRCC compared with that in normal tissues is related to longer overall survival in patients with ccRCC. XCR1 knockdown significantly increased RCC cells proliferation and migration, and decreased apoptosis. XCR1 might be used as a prognostic biomarker in ccRCC in the future.

Mining therapeutic and prognostic significance of STATs in renal cell carcinoma with bioinformatics analysis

Renal cell carcinoma is one of the most common malignancies with high morbidity and mortality. STAT proteins play a significant role in cell biological behavior and immune response associated with cancer progression. In our study, the datasets analyzed for the expression and potential functions can be found in several bioinformatics analysis tools. We found that STAT1/2/4/6 were upregulated in RCC while STAT3/5B were downregulated. The expression of STAT2/4/5B were significantly associated with the pathological stage of RCC patients. RCC patients with high expression of STAT2/4 and low/medium expression of STAT5B had a poor overall survival. The function of STATs and the neighboring genes mainly enriched in JAK-STAT signaling pathway and NOD-like receptor signaling pathway. Several transcription factor, kinase, and miRNA targets were identified. Close correlations were obtained between immune cell infiltration and STATs in RCC. Our results have provided novel insights for the selection of immunotherapeutic targets and prognostic biomarkers.

Circular RNAs in renal cell carcinoma: implications for tumorigenesis, diagnosis, and therapy

Renal cell carcinoma (RCC) is the most common malignant kidney tumor and has a high incidence rate. Circular RNAs (circRNAs) are noncoding RNAs with widespread distribution and diverse cellular functions. They are highly stable and have organ- and tissue-specific expression patterns. CircRNAs have essential functions as microRNA sponges, RNA-binding protein- and transcriptional regulators, and protein translation templates. Recent reports have shown that circRNAs are abnormally expressed in RCC and act as important regulators of RCC carcinogenesis and progression. Moreover, circRNAs have emerged as potential biomarkers for RCC diagnosis and prognosis and targets for developing new treatments. However, further studies are needed to better understand the functions of circRNAs in RCC. In this review, we summarize and discuss the recent research progress on RCC-associated circRNAs, with a focus on their potential for RCC diagnosis and targeted therapy.

Exosomal circular RNA_400068 promotes the development of renal cell carcinoma via the miR‑210‑5p/SOCS1 axis

Renal cell carcinoma (RCC) is a common type of malignancy in the kidney, which accounts for ~80% of the cases within adult patients. The pathogenesis of RCC is complicated and involves alterations at both genetic and epigenetic levels. The aim of the present study was to investigate the roles of circRNAs in the pathogenesis of RCC. In the current study, exosomes were isolated via gradient centrifugation and identified using transmission electron microscope. The expression levels of circular RNA (circ)_400068, microRNA (miR)‑210‑5p and suppressor of cytokine signaling 1 (SOCS1) were examined using reverse transcription‑quantitative PCR. Cell proliferation was evaluated using a Cell Counting Kit‑8 assay, and the apoptotic rate was determined in transfected cells using flow cytometry. The protein expression levels of proliferation‑ and apoptosis‑associated genes were assessed via western blot analysis. Upregulation of circ_400068 was detected in RCC plasma exosomes, tissue samples and cells. Additionally, treatment with exosomal circ_400068 promoted the proliferation and inhibited the apoptosis of healthy kidney cells, which were abrogated by short hairpin RNA‑circ_400068. The results suggested that miR‑210‑5p was a potential downstream molecule of circ_400068, and SOCS1 was a novel target of miR‑210‑5p. Moreover, circ_400068 regulated the proliferation of HK‑2 cells by targeting the miR‑210‑5p/SOCS1 axis, as the effects on cell proliferation caused by treatment using exosomes isolated from the culture media of RCC cells were abolished by miR‑210‑5p mimics. It was found that enhanced cell proliferation induced by miR‑210‑5p inhibitors was attenuated by the knockdown of SOCS1, while the influences triggered by miR‑210‑5p mimics were reversed by SOCS1 overexpression. Collectively, the present findings provided a novel insight into the crucial regulatory functions of circ_400068 in RCC, and the circ_400068/miR‑210‑5p/SOCS1 axis could be a candidate therapeutic target for the treatment of patients with RCC.

JAK3 is a potential biomarker and associated with immune infiltration in kidney renal clear cell carcinoma

Kidney renal clear cell carcinoma (KIRC) is one of the most common cancers globally, with an overall poor prognosis. The Janus kinase (JAK) family plays an essential role in cellular mechanisms such as proliferation, metastasis, invasion, and immunity. In our study, various web-portals were used to explore the expression and clinical significance of JAK3 in KIRC. JAK3 expression was significantly up-regulated in KIRC tissues. Patients with KIRC having high JAK3 levels displayed a substantially decreased disease-free survival rate and overall survival rate. Significant correlations were obtained between JAK3 expression and the abundance of immune cells and immune biomarker sets. Enrichment function analysis revealed that gene function significantly correlated with JAK3, which was primarily associated with the immune response, JAK-STAT signaling pathway, Ras signaling pathway via several cancer-related kinases, miRNAs, and transcription factors. Moreover, we also identified several kinase, miRNA or transcription factor targets of JAK3 in KIRC. The hub genes (JAK3, FCHO1, INSl3, DEF6, and GPR132) were associated with the activation or inhibition of several famous cancer related pathways. Our results demonstrated that JAK3 is a potential biomarker and associated with immune infiltration in KIRC.

Interferon α in cancer immunoediting: From elimination to escape

Interferon α (IFNα) is a cytokine that mediates diverse immune responses to tumours. It is the oldest immune-based oncologic drug and has been widely used to treat various malignancies in humans. Yet, the use of IFNα in cancer therapy has only resulted in limited success and even led to worse clinical outcomes under certain instances. The emergence of the cancer immunoediting concept-which implicates the host immune system in promoting tumour growth-recapitulates the need to evaluate the immune functions of IFNα. This review proposes that IFNα has dual opposing roles in cancer development based on the mutational status of its signalling components, which determines the expression of anti- or pro-tumorigenic IFN-stimulated genes (ISGs). This duality may translate into new applications of IFNα in cancer immunotherapy.

Decreased expression of TXNIP predicts poor prognosis in patients with clear cell renal cell carcinoma

Accumulating evidence has demonstrated that thioredoxin interacting protein (TXNIP) is abnormally expressed in a variety of malignant tumors and functions as a tumor suppressor. However, the association between TXNIP and clear cell renal cell carcinoma (CCRCC) has not yet been fully elucidated. The aim of the present study was to evaluate the role of TXNIP in CCRCC using The Cancer Genome Atlas (TCGA) database. The RNA sequencing data and corresponding clinical data were collected from TCGA database. The association between TXNIP and patient clinicopathological characteristics was analyzed using analysis of variance and logistic regression. The Kaplan-Meier method and Cox proportional hazards model were used to assess the association between TXNIP and overall survival. Gene Set Enrichment Analysis (GSEA) was used to explore the associated signaling pathways. TXNIP expression was identified to be decreased in CCRCC tissues compared with normal tissues. The decreased expression of TXNIP in CCRCC was significantly associated with clinical stage [OR=0.509 for III vs. I (P=0.002); OR=0.527 for IV vs. I (P=0.012)], T stage [OR=0.552 for T3 vs. T1 (P=0.002)] and grade [OR=0.261 for G4 vs. G1 (P=0.027)]. Kaplan-Meier survival analysis indicated that cases of CCRCC with low TXNIP expression were associated with poorer prognoses compared with those with a high expression level (P=0.002). Univariate and multivariate Cox analyses indicated that TXNIP was an independent prognostic factor in CCRCC. GSEA revealed that 6 pathways exhibited significant differential enrichment in the TXNIP high-expression phenotype, including the WNT signaling pathway, the mitogen-activated protein kinase (MAPK) signaling pathway, the phosphatidylinositol signaling system, the transforming growth factor-β (TGF-β) signaling pathway, autophagy and the Janus kinase (JAK)-STAT signaling pathway. Taken together, the results of the present study indicate that TXNIP expression may be a potential prognostic marker for patients with CCRCC. In addition, the WNT signaling pathway, MAPK signaling pathway, phosphatidylinositol signaling system, TGF-β signaling pathway, autophagy and the JAK-STAT signaling pathway may be the crucial pathways regulated by TXNIP in CCRCC.

lncRNA ROR promotes the progression of renal cell carcinoma through the miR‑206/VEGF axis

Renal cell carcinoma (RCC) is the most common kidney malignancy, responsible for ~80% of all cases in adults. The pathogenesis of RCC is complex, involving alterations at both the genetic and epigenetic levels. Numerous signaling pathways, such as PI3K/Akt/mTOR and Wnt‑β‑catenin have been demonstrated to be associated with the tumorigenesis and development of RCC. Long non‑coding RNAs (lncRNAs) are functional RNA molecules involved in the initiation and progression of cancer, and investigating the effects of lncRNA could facilitate the development of novel treatments. The lncRNA regulator of reprogramming (ROR) is aberrantly expressed in a variety of tumors. However, its underlying mechanisms remain largely unknown. In the present study, ROR was found to be upregulated and microRNA (miR)‑206 was found to be downregulated in RCC tissues and cells. Furthermore, the knockdown of ROR inhibited the proliferation, migration and invasion of RCC cells. It was found that ROR binds to miR‑206, and that ROR‑induced cell proliferation and metastasis were reversed by the overexpression of miR‑206. In addition, the levels of miR‑206 and ROR were negatively correlated in RCC tissues. Furthermore, the overexpression of miR‑206 notably suppressed the proliferation, migration and invasion of RCC cells, and these effects were enhanced by the knockdown of vascular endothelial growth factor (VEGF); cell growth and metastasis induced by miR‑206 inhibitors could be reversed by the knockdown of VEGF. In addition, the expression levels of miR‑206 and VEGF were inversely correlated in RCC samples. In summary, the results of the present study revealed that ROR was upregulated in RCC tissues, which promoted tumor progression by regulating the miR‑206/VEGF axis. The present findings provided a novel insight into the potential functions of ROR in RCC, and the ROR/miR‑206/VEGF pathway may be a promising therapeutic target for the treatment of patients with RCC.

Plasticity of Type I Interferon-Mediated Responses in Cancer Therapy: From Anti-tumor Immunity to Resistance

The efficacy of several therapeutic strategies against cancer, including cytotoxic drugs, radiotherapy, targeted immunotherapies and oncolytic viruses, depend on intact type I interferon (IFN) signaling for the promotion of both direct (tumor cell inhibition) and indirect (anti-tumor immune responses) effects. Malfunctions of this pathway in tumor cells or in immune cells may be responsible for the lack of response or resistance. Although type I IFN signaling is required to trigger anti-tumor immunity, emerging evidence indicates that chronic activation of type I IFN pathway may be involved in mediating resistance to different cancer treatments. The plastic and dynamic features of type I IFN responses should be carefully considered to fully exploit the therapeutic potential of strategies targeting IFN signaling. Here, we review available evidence supporting the involvement of type I IFN signaling in mediating resistance to various cancer therapies and highlight the most promising modalities that are being tested to overcome resistance.

Long non-coding RNAs in renal cell carcinoma: A systematic review and clinical implications

Renal cell carcinoma is one of the most common malignancy in adults, its prognosis is poor in an advanced stage and early detection is difficult due to the lack of molecular biomarkers. The identification of novel biomarkers for RCC is an urgent and meaningful project. Long non-coding RNA (lncRNA) is transcribed from genomic regions with a minimum length of 200 bases and limited protein-coding potential. Recently, lncRNAs have been greatly studied in a variety of cancer types. They participate in a wide variety of biological processes including cancer biology. In this review, we provide a new insight of the profiling of lncRNAs in RCC and their roles in renal carcinogenesis, with an emphasize on their potential in diagnosis, prognosis and potential roles in RCC therapy.

Restoration of IRF1-dependent anticancer effects by MEK inhibition in human cancer cells

Interferon regulatory factor (IRF1) is a potent antiviral, antitumor and immune regulatory protein. Recently, we found that activated Ras/MEK inhibits antiviral response by downregulating IRF1 expression and renders cancer cells susceptible to oncolytic viruses. In this study, we sought to determine whether IRF1 downregulation underlies oncogenesis induced by Ras/MEK activation in human cancer cells. Treatment of the MEK inhibitor U0126 promoted IRF1 expression in 7 of 11 cancer cell lines we tested. IRF1 promotion was also observed in human cancer cell lines treated with different MEK inhibitors or with RNAi oligonucleotides against extracellular signal-regulated kinases (ERKs). Restoration of the expression of antitumor genes, p27 and p53 upregulated modulator of apoptosis (PUMA), by MEK inhibition was less in IRF1 shRNA knockdown cancer cells than in vector control cancer cells, suggesting that Ras/MEK targets IRF1 for the downregulation of the antitumor genes. Moreover, apoptosis induction by U0126 was significantly reduced in IRF1 shRNA knockdown cells than vector control cells. This study demonstrates that IRF1 expression is suppressed by activated Ras/MEK in human cancer cells and that IRF1 plays essential roles in apoptosis induced by Ras/MEK inhibition.

Oncogenic Ras inhibits IRF1 to promote viral oncolysis

Oncolytic viruses exploit common molecular changes in cancer cells, which are not present in normal cells, to target and kill cancer cells. Ras transformation and defects in type I interferon (IFN)-mediated antiviral responses are known to be the major mechanisms underlying viral oncolysis. Previously, we demonstrated that oncogenic RAS/Mitogen-activated protein kinase kinase (Ras/MEK) activation suppresses the transcription of many IFN-inducible genes in human cancer cells, suggesting that Ras transformation underlies type I IFN defects in cancer cells. Here, we investigated how Ras/MEK downregulates IFN-induced transcription. By conducting promoter deletion analysis of IFN-inducible genes, namely guanylate-binding protein 2 and IFN gamma inducible protein 47 (Ifi47), we identified the IFN regulatory factor 1 (IRF1) binding site as the promoter region responsible for the regulation of transcription by MEK. MEK inhibition promoted transcription of the IFN-inducible genes in wild type mouse embryonic fibroblasts (MEFs), but not in IRF1(-/-) MEFs, showing that IRF1 is involved in MEK-mediated downregulation of IFN-inducible genes. Furthermore, IRF1 protein expression was lower in RasV12 cells compared with vector control NIH3T3 cells, but was restored to equivalent levels by inhibition of MEK. Similarly, the restoration of IRF1 expression by MEK inhibition was observed in human cancer cells. IRF1 re-expression in human cancer cells caused cells to become resistant to infection by the oncolytic vesicular stomatitis virus strain. Together, this work demonstrates that Ras/MEK activation in cancer cells downregulates transcription of IFN-inducible genes by targeting IRF1 expression, resulting in increased susceptibility to viral oncolysis.

Abrogation of STAT3 signaling cascade by zerumbone inhibits proliferation and induces apoptosis in renal cell carcinoma xenograft mouse model

Persistent activation of signal transducer and activator of transcription 3 (STAT3) is one of the characteristic features of renal cell carcinoma (RCC) and often linked to its deregulated proliferation, survival, and angiogenesis. In the present report, we investigated whether zerumbone, a sesquiterpene, exerts its anticancer effect through modulation of STAT3 activation pathway. The pharmacological effect of zerumbone on STAT3 activation, associated protein kinases and phosphatase, and apoptosis was investigated using both RCC cell lines and xenograft mouse model. We observed that zerumbone suppressed STAT3 activation in a dose- and time-dependent manner in RCC cells. The suppression was mediated through the inhibition of activation of upstream kinases c-Src, Janus-activated kinase 1, and Janus-activated kinase 2. Pervanadate treatment reversed zerumbone-induced downregulation of STAT3, suggesting the involvement of a tyrosine phosphatase. Indeed, we found that zerumbone induced the expression of tyrosine phosphatase SHP-1 that correlated with its ability to inhibit STAT3 activation. Interestingly, deletion of SHP-1 gene by siRNA abolished the ability of zerumbone to inhibit STAT3 activation. The inhibition of STAT3 activation by zerumbone also caused the suppression of the gene products involved in proliferation, survival, and angiogenesis. Finally, when administered i.p., zerumbone inhibited STAT3 activation in tumor tissues and the growth of human RCC xenograft tumors in athymic nu/nu mice without any side effects. Overall, our results suggest for the first time that zerumbone is a novel blocker of STAT3 signaling cascade and thus has an enormous potential for the treatment of RCC and other solid tumors.

Phosphorylated signal transducer and activator of transcription 1 is a potential predictor of interferon response in patients with advanced renal cell carcinoma

The present study aimed to evaluate the expression status of Janus kinase (JAK)-Signal Transducer and Activator of Transcription (STAT) in renal cell carcinoma and benign renal tissue, and identify a potential biomarker for interferon (IFN) response prediction. A total of 32 specimens of human renal cell carcinoma and 10 specimens of benign renal tissue were harvested from surgically removed kidneys. The expression levels of JAK‑STAT were determined by immunohistochemical staining and quantitative polymerase chain reaction. Furthermore, the expression levels of JAK‑STAT in renal cell carcinoma tissues that were stimulated with IFN-α were quantified by western blot analysis. The positive expression rates of JAK1, STAT1 and phosphorylated (P)‑STAT1 in the renal cell carcinomas were significantly lower than that in the benign renal tissues (25.0, 31.2, and 12.5% vs. 70.0, 50.0, and 70.0%, respectively; P<0.05). The relative expression levels of JAK1 (0.696 ± 0.102) and STAT1 mRNA (0.341 ± 0.068) in the tumor tissue were lower than those in the benign tissue (0.957 ± 0.103 and 0.547 ± 0.082, respectively; P<0.05). IFN stimulation enhanced the expression levels of P‑STAT1 in the renal cell carcinoma tissues, and enhancement of the P‑STAT1 expression levels was associated with tumor relapse and metastasis. In conclusion, P‑STAT1 is a potential predictor of IFN response in patients with advanced renal cell carcinoma.

Icaritin inhibits JAK/STAT3 signaling and growth of renal cell carcinoma

Signal transducer and activator of transcription-3 (STAT3) is critical for cancer progression by regulating tumor cell survival, proliferation, and angiogenesis. Herein, we investigated the regulation of STAT3 activation and the therapeutic effects of Icaritin, a prenyl flavonoid derivative from Epimedium Genus, in renal cell carcinoma (RCC). Icaritin showed significant anti-tumor activity in the human and mouse RCC cell lines, 786-O and Renca, respectively. Icaritin inhibited both constitutive and IL-6-induced phospho-STAT3 (STAT3(Y705)) and reduced the level of STAT3-regulated proteins Bcl-xL, Mcl-1, Survivin, and CyclinD1 in a dose-dependent manner. Icaritin also inhibited activation of Janus-activated kinase-2 (JAK2), while it showed minimal effects on the activation of other key signaling pathways, including AKT and MAPK. Expression of the constitutively active form of STAT3 blocked Icaritin-induced apoptosis, while siRNA directed against STAT3 potentiated apoptosis. Finally, Icaritin significantly blunted RCC tumor growth in vivo, reduced STAT3 activation, and inhibited Bcl-xL and Cyclin E, as well as VEGF expression in tumors, which was associated with reduced tumor angiogenesis. Overall, these results suggest that Icaritin strongly inhibits STAT3 activation and is a potentially effective therapeutic option for the treatment of renal cell carcinoma.

A study exploring critical pathways in clear cell renal cell carcinoma

Renal cell carcinoma (RCC) is the most lethal type of cancer in the urinary system and often presents as a metastatic disease. Furthermore, there are no effective treatments for the disease. Several studies based on gene expression profiling have been performed with the aim of gaining insights into the pathogenesis of RCC; however, few studies have investigated RCC at the pathway level to search for the possible pathways involved in clear cell RCC (CCRCC). In this study, gene set enrichment analysis (GSEA) was conducted on microarray datasets from CCRCC tissue. DAVID functional enrichment analysis was performed based on the dysregulated genes that were identified in a meta-analysis performed on the microarray datasets from CCRCC tissue. In GSEA, 17 down- and 12 upregulated pathways coexisted in six datasets. The majority of the upregulated pathways were associated with the immune system. In addition, 32 dysregulated pathways were obtained from DAVID functional enrichment analysis, based on the abnormal genes identified by meta-analysis. This study demonstrated that cross-GSEA is a useful method for exploring the critical pathways involved CCRCC; however, an individual dataset with a small sample may introduce bias. A cross-GSEA based on certain well-designed datasets may be required to further the progress made in this study, following the analysis of its results.

Zoledronic acid sensitizes renal cell carcinoma cells to radiation by downregulating STAT1

Zoledronic acid (ZOL), a third-generation bisphosphonate that strongly inhibits osteoclast activity, is widely used for the treatment of bone metastasis from a variety of malignancies, including renal cell carcinoma (RCC). We previously reported that zoledronic acid (ZOL) clinically potentiates antitumor effects of radiotherapy (RT) on bone metastases from RCC. To date, however, it remains unknown whether ZOL radiosensitizes RCC and if it does, how. Here, we demonstrated that ZOL directly radiosensitizes RCC cells independent of osteoclast activity by potentiating the caspase-3-mediated apoptosis pathway. The radiosensitization by ZOL was observed in 786-O, A-498, and ACHN cells but not in Caki-1 cells. As its underlying molecular mechanism, we found that the signal transducer and activator of transcription 1 (STAT1) plays a key role. The three RCC cell lines, in which ZOL exerted a radiosensitizing effect, expressed STAT1 abundantly but Caki-1 cells did not. ZOL downregulated endogenous STAT1 expression in 786-O, A-498, and ACHN cells by a post-transcriptional modification. We confirmed that knockdown of endogenous STAT1 by siRNA sensitized 786-O cells to RT equivalently to ZOL, and that introduction of exogenous STAT1 rendered Caki-1 cells more RT-resistant. This is the first study to clarify the molecular mechanism by which ZOL directly radiosensitizes tumor cells. Because tumor cells commonly overexpress STAT1 and ZOL reportedly radiosensitizes various types of tumor cells, ZOL warrants further clinical and translational studies as a potent radiosensitizer against RT-resistant tumors overexpressing STAT1.

Suppression of IFN-induced transcription underlies IFN defects generated by activated Ras/MEK in human cancer cells

Certain oncolytic viruses exploit activated Ras signaling in order to replicate in cancer cells. Constitutive activation of the Ras/MEK pathway is known to suppress the effectiveness of the interferon (IFN) antiviral response, which may contribute to Ras-dependent viral oncolysis. Here, we identified 10 human cancer cell lines (out of 16) with increased sensitivity to the anti-viral effects of IFN-α after treatment with the MEK inhibitor U0126, suggesting that the Ras/MEK pathway underlies their reduced sensitivity to IFN. To determine how Ras/MEK suppresses the IFN response in these cells, we used DNA microarrays to compare IFN-induced transcription in IFN-sensitive SKOV3 cells, moderately resistant HT1080 cells, and HT1080 cells treated with U0126. We found that 267 genes were induced by IFN in SKOV3 cells, while only 98 genes were induced in HT1080 cells at the same time point. Furthermore, the expression of a distinct subset of IFN inducible genes, that included RIGI, GBP2, IFIT2, BTN3A3, MAP2, MMP7 and STAT2, was restored or increased in HT1080 cells when the cells were co-treated with U0126 and IFN. Bioinformatic analysis of the biological processes represented by these genes revealed increased representation of genes involved in the anti-viral response, regulation of apoptosis, cell differentiation and metabolism. Furthermore, introduction of constitutively active Ras into IFN sensitive SKOV3 cells reduced their IFN sensitivity and ability to activate IFN-induced transcription. This work demonstrates for the first time that activated Ras/MEK in human cancer cells induces downregulation of a specific subset of IFN-inducible genes.

Interferon-gamma-induced nitric oxide inhibits the proliferation of murine renal cell carcinoma cells

Renal cell carcinoma (RCC) remains one of the most resistant tumors to systemic chemotherapy, radiotherapy, and immunotherapy. Despite great progress in understanding the basic biology of RCC, the rate of responses in animal models and clinical trials using interferons (IFNs) has not improved significantly. It is likely that the lack of responses can be due to the tumor's ability to develop tumor escape strategies. Currently, the use of targeted therapies has improved the clinical outcomes of patients with RCC and is associated with an increase of Th1-cytokine responses (IFNγ), indicating the importance of IFNγ in inhibiting tumor proliferation. Thus, the present study was designed to investigate a new mechanism by which IFNγ mediates direct anti-proliferative effects against murine renal cell carcinoma cell lines. When cultured RCC cell lines were exposed to murine recombinant IFNγ, a dose dependent growth inhibition in CL-2 and CL-19 cells was observed; this effect was not observed in Renca cells. Growth inhibition in CL-2 and CL-19 cell lines was associated with the intracellular induction of nitric oxide synthase (iNOS) protein, resulting in a sustained elevation of nitric oxide (NO) and citrulline, and a decrease in arginase activity. The inhibition of cell proliferation appears to be due to an arrest in the cell cycle. The results indicate that in certain RCC cell lines, IFNγ modulates L-arginine metabolism by shifting from arginase to iNOS activity, thereby developing a potent inhibitory mechanism to encumber tumor cell proliferation and survival. Elucidating the cellular events triggered by IFNγ in murine RCC cell lines will permit anti-tumor effects to be exploited in the development of new combination therapies that interfere with L-arginine metabolism to effectively combat RCC in patients.

Interferon-α induces G1 cell-cycle arrest in renal cell carcinoma cells via activation of Jak-Stat signaling

The purpose of this study was to clarify the mechanism of IFN-α resistance in RCC. The effects of IFN-α on induction of apoptosis and cell-cycle arrest were analyzed by flow cytometric analysis. Jak-Stat pathway components induced by IFN-α was evaluated using Western blotting. The results suggested that IFN-α caused growth inhibition of RCC cell lines via arrest in the G1 phase without inducing apoptosis. The resistance of RCC to IFN-α was associated with the low expression of Stat1. This study indicated that the Jak-Stat pathway should be considered a primary target for improving the response of RCC to IFN-α treatment.

Suppression of SOCS3 increases susceptibility of renal cell carcinoma to interferon-α

Interferon (IFN)-α is one of the most commonly used agents in immunotherapy for patients with advanced stage renal cell carcinoma. However, because of the drug resistance to IFN-α, its benefits are limited. In this study, we examined whether repression of suppressor of cytokine signaling (SOCS) proteins, which are involved in the IFN-induced signaling pathway, can overcome the IFN resistance of renal cell carcinoma. The effect of IFN-α on SOCS3 expression and cell proliferation was examined using IFN-resistant 786-O and IFN-sensitive ACHN cell lines. The effects of SOCS3-targeted siRNA on 786-O xenografts were determined by SOCS3 expression, morphological observation, and tumor volume. The SOCS3 mRNA expression level was significantly increased by IFN-α stimulation in 786-O, but not in ACHN cells. The overexpression of SOCS3 by gene transfection in ACHN cells significantly inhibited the growth-inhibitory effect of IFN-α. Suppression of SOCS3 expression in 786-O cells by siRNA activated the IFN signaling pathway through signal transducer and activator of transcription 1 phosphorylation and recovered sensitivity to IFN-α. An in vivo study indicated that co-administration of SOCS3-targeted siRNA promoted IFN-α-induced cell death and growth suppression in 786-O cell xenograft in nude mice. Morphological observation of the tumors revealed the inhibition of SOCS3-induced apoptosis, invasion of inflammatory cells and fibrosis. SOCS3 could be a key component in the resistance to IFN treatment of renal cell carcinoma. Silencing SOCS3 gene expression could be an effective strategy to enhance the antitumor effect of IFN in human renal cell carcinoma cells.

Changes in glucose and glutamine lymphocyte metabolisms induced by type I interferon α

In lymphocytes (LY), the well-documented antiproliferative effects of IFN-α are associated with inhibition of protein synthesis, decreased amino acid incorporation, and cell cycle arrest. However, the effects of this cytokine on the metabolism of glucose and glutamine in these cells have not been well investigated. Thus, mesenteric and spleen LY of male Wistar rats were cultured in the presence or absence of IFN-α, and the changes on glucose and glutamine metabolisms were investigated. The reduced proliferation of mesenteric LY was accompanied by a reduction in glucose total consumption (35%), aerobic glucose metabolism (55%), maximal activity of glucose-6-phosphate dehydrogenase (49%), citrate synthase activity (34%), total glutamine consumption (30%), aerobic glutamine consumption (20.3%) and glutaminase activity (56%). In LY isolated from spleen, IFNα also reduced the proliferation and impaired metabolism. These data demonstrate that in LY, the antiproliferative effects of IFNα are associated with a reduction in glucose and glutamine metabolisms.

Interferon-alpha induces high expression of APOBEC3G and STAT-1 in vitro and in vivo

To investigate whether the JAK-STAT (Janus kinase-signal transducers and activators of transcription) pathway participates in the regulation of APOBEC3G (Apolipoprotein B mRNA-editing enzyme, catalytic polypeptide-like 3G) gene transcription and to study the molecular mechanisms of interferon resistance in patients with chronic hepatitis B (CHB), changes in APOBEC3G and STAT-1 expression levels in HepG2.2.15 cells after treatment with various concentrations of IFN-α, were detected using real-time RT-PCR and Western-blot. In addition, the differences in STAT-1 and APOBEC3G expression in liver tissues were also observed in patients with different anti-viral responses to IFN-α. It is found that IFN-α suppressed HBV replication and expression markedly in HepG2.2.15 cells, and simultaneously enhanced APOBEC3G expression in a dose- or time-dependent manner within a certain range. Moreover, a corresponding gradual increase in STAT-1 expression levels was also observed. The expression levels of STAT-1 and APOBEC3G in the liver of CHB patients with a complete response to IFN-α are significantly higher than that of the patients with non-response to IFN-α treatment. It is suggested that inducing intracellular APOBEC3G expression may be one of anti-HBV mechanisms of IFN-α, and IFN-α-induced APOBEC3G expression may be via the JAK-STAT signaling pathway. Moreover, interferon resistance may be related to the down-regulation of STAT-1 expression in the patients who had non-response to IFN-α treatment.

NF-kappaB activation mediates resistance to IFN beta in MLL-rearranged acute lymphoblastic leukemia

Acute lymphoblastic leukemia (ALL) harboring the t(4;11) translocation is associated with a very poor prognosis; innovative treatment strategies are required to improve the current 5-year survival rate of 30-40%. Interferon beta (IFN beta) has shown promise in the treatment of both solid and hematologic malignancies, although the short half-life and toxicity associated with high doses have limited its clinical utility. To overcome these limitations, we investigated the effect of continuous, gene transfer-mediated delivery of IFN beta using adeno-associated virus (AAV)-mediated expression, on ALL cells with the t(4;11) translocation. We found that this method of IFN beta delivery resulted in complete remission of leukemia in a murine model. However, leukemic cells eventually became resistant to IFN beta and relapse was observed. Activation of NF-kappaB was identified as a mechanism for IFN beta resistance, and inhibition of NF-kappaB activity in resistant cells sensitized cells to IFN beta. IFN beta combined with agents that inhibit NF-kappaB could have therapeutic potential in the treatment of children with mixed lineage leukemia subtype ALL.

Low expression of microphthalmia-associated transcription factor, a potential molecular target for interferon-alpha susceptibility, is associated with metastasis in renal cell carcinoma

We previously reported that microarray expression profiling identified several candidate genes in association with interferon-alpha (IFN-alpha) response in renal cell carcinoma (RCC) cell lines (Cancer Sci 2007; 98: 529). Among them, we focused on microphthalmia-associated transcription factor (MITF), because its expression profile correlated well with IFN-alpha-response status. In addition, we investigated the clinical significance of the expression level of MITF using surgical specimens. RNA was extracted from 14 RCC cell lines and 65 RCC samples and was used in this study. Transfection of MITF cDNA into IFN-alpha-resistant RCC cell lines resulted in elevation of MITF expression and acquisition of IFN-alpha-sensitivity by quantitative PCR and WST-8 assay, respectively. Statistical analysis revealed that low MITF mRNA expression in RCC samples was significantly correlated with the presence of metastasis and poor survival of the patient. However, the correlation between MITF expression and IFN-alpha response was not obvious in the clinical cases. MITF gene transfection elevated IFN-alpha-sensitivity in RCC cell lines, suggesting that this gene is a target molecule for modulation of the IFN-alpha response. Quantification of MITF mRNA expression might be clinically useful to predict metastasis and survival of patients with RCC.

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

To support the role of interferon (IFN)-alpha and sorafenib combination therapy against renal cell carcinoma (RCC), the effects of IFN-alpha and sorafenib on tumor growth, vascular endothelial growth factor (VEGF) production, and phosphorylation levels of extracellular signal-regulated kinase (ERK) and mitogen-activated protein/ERK kinase (MEK) were examined using several cultured RCC cell lines (ACHN, Caki-1, Caki-2, SMKT-R1, SMKT-R2, SMKT-R3 and SMKT-R4). IFN-alpha or sorafenib alone inhibited the proliferation of all the cell lines except Caki-2, while combined treatment with the two agents showed enhanced inhibitory effects compared to treatment with each agent alone. VEGF production was inhibited by IFN-alpha alone in ACHN and SMKT-R2 cells and by sorafenib alone in ACHN, Caki-1, SMKT-R1 and SMKT-R2 cells. However, sorafenib increased VEGF production by Caki-2 cells. Interestingly, combined treatment with the two agents suppressed VEGF production by SMKT-R1 and SMKT-R2 cells more strongly than IFN-alpha or sorafenib alone. Although phosphorylated ERK (p-ERK) was increased after 30 min of treatment with IFN-alpha alone, no difference was observed between control and IFN-alpha-treated cells after 2 h. Sorafenib decreased p-ERK in ACHN, Caki-1, SMKT-R1 and SMKT-R2 cells, but increased p-ERK in Caki-2, SMKT-R3 and SMKT-R4 cells, after 2 h. Combined treatment with IFN-alpha and sorafenib decreased p-ERK compared to treatment with each agent alone in all cell lines except Caki-2. However, IFN-alpha did not inhibit the p-ERK increase induced by sorafenib in Caki-2 cells. Phosphorylated MEK showed similar patterns to p-ERK after the various treatments. In conclusion, combined treatment with IFN-alpha and sorafenib suppressed cell proliferation and VEGF production more strongly than treatment with each agent alone in several RCC cell lines.

Global analysis of metastasis-associated gene expression in primary cultures from clinical specimens of clear-cell renal-cell carcinoma

Metastatic clear-cell renal-cell carcinoma (ccRCC) has a poor prognosis and unpredictable course, and there are no molecular markers that reliably predict ccRCC metastasis. In this study, ccRCC specimens from 84 patients were directly cultured in vitro. Primary cultures from 38 of 94 specimens contained more than 90% tumor cells at the fourth passage. After identification by immunostaining, the primary cultures of metastatic and nonmetastatic ccRCC specimens from the age- and gender-matched patients were subjected to cDNA microarray assays. A total of 842 differentially expressed genes with a FDR (false discovery rate) of 4.79% were identified. Pathway analysis and co-occurrence with "cancer", "metastasis" and "invasion" in the literature annotations functionally enriched the 842 genes and provided an indication of the reliability of our microarray assays. Novel genes associated with metastasis were selected based on protein-protein interactions between 205 differentially expressed genes that co-occurred with "metastasis" and those that did not co-occur with "metastasis" on Medline, and the results of co-expression analysis between the co-occurred genes and unpublished genes. FSTL1, AV722783, SLC15A1, DDX17, ORC2L and PKMYT1 were found to be potential ccRCC metastasis-associated novel genes, according to expression patterns in cultures and tumor tissues. Interestingly, the upregulated genes (CAV1, PKMYT1 and ORC2L) were also upregulated and the downregulated genes (FSTL1, GSTM3, CYR61, SLC15A1 and AV722783) were also downregulated in the primary ccRCC specimens compared with expression in adjacent renal tissues in 37 patients. This study has identified new candidate biomarkers and targets for the early diagnosis and treatment of ccRCC metastasis.