Nuclear FOXO3 predicts adverse clinical outcome and promotes tumor angiogenesis in neuroblastoma

Autosomal Dominant Polycystic Kidney Disease-Related Multifocal Renal Cell Carcinoma: A Narrative Iconographic Review

Autosomal Dominant Polycystic Kidney Disease (ADPKD) is the most common inheritable disease of cystic degeneration in the kidney. ADPKD is a significant cause of end-stage renal disease (ESRD). Autosomal Dominant Polycystic Liver Disease (ADPLD) results in substantial PLD with minimal PKD. Currently, there are eight genes which have been associated with ADPKD (PKD1 and PKD2), ADPLD (PRKCSH, SEC63, LRP5, ALG8, and SEC61B), or both (GANAB). The severity of ADPKD can show an extremely broad range, but the evolution to ESRD is doubtless unavoidable. In some patients, carcinogenesis develops with inflammation as a potential promoting factor. In this chapter, we illustrate the severity of ADPKD and the fate to develop renal cell carcinoma (RCC).

Technical Implications of the Chicken Embryo Chorioallantoic Membrane Assay to Elucidate Neuroblastoma Biology

The chorioallantoic membrane (CAM) can be used as a valuable research tool to examine tumors. The CAM can be used to investigate processes such as migration, invasion, and angiogenesis and to assess novel antitumor drugs. The CAM can be used to establish tumors in a straightforward, rapid, and cost-effective manner via xenotransplantation of cells or tumor tissues with reproducible results; furthermore, the use of the CAM adheres to the three "R" principle, i.e., replace, reduce, and refine. To achieve successful tumor establishment and survival, several technical aspects should be taken into consideration. The complexity and heterogeneity of diseases including neuroblastoma and cancers in general and their impact on human health highlight the importance of preclinical models that help us describe tumor-specific biological processes. These models will not only help in understanding tumor biology, but also allow clinicians to explore therapeutic alternatives that will improve current treatment strategies. In this review, we summarize the technical characteristics as well as the main findings regarding the use of this model to study neuroblastoma for angiogenesis, metastasis, drug sensitivity, and drug resistance.

Demystifying neuroblastoma malignancy through fractal dimension, entropy, and lacunarity

PURPOSE

Neuroblastoma is a pediatric solid tumor with a prognosis associated with histology and age of the patient, which are the parameters of the well-established current classification (Shimada classification). Despite the development of new treatment options, the prognosis of high-risk neuroblastoma patients is still poor. Therefore, there is a continuous need to stratify the children suffering from this tumor. A mathematical and computational approach is proposed to enable automatic and precise cancer diagnosis on the histological slide.

METHODS

We targeted the complexity of neuroblastoma by calculating its image entropy (S), fractal dimension (FD), and lacunarity (λ) in a combined mathematical code. First, we tested the proposed method for patient-derived glioma images. It allowed distinguishing between normal brain tissue, grade II, and grade III glioma, which harbor different outcomes.

RESULTS

In neuroblastoma, our analysis of image's FD, S, and λ combined with a machine learning algorithm automatically predicted tumor malignancy with a receiver operating characteristic curve of 0.82. FD, S, and λ distinguish between neuroblastoma and ganglioneuroma, but they only partially differentiate between the normal samples and the other classes. Ganglioneuroma, the most differentiated form, and poorly-differentiated neuroblastoma display different values of FD, S, and λ.

CONCLUSIONS

FD, S, and λ of imaging recognize groups in neuroblastic tumors. We suggest that future studies including these features may challenge the current Shimada classification of neuroblastoma with categories of favorable and unfavorable histology. It is expected that this methodology could trigger multicenter studies and potentially find practical use in the clinical setting of children's hospitals worldwide.

Proteogenomics of diffuse gliomas reveal molecular subtypes associated with specific therapeutic targets and immune-evasion mechanisms

Diffuse gliomas are devastating brain tumors. Here, we perform a proteogenomic profiling of 213 retrospectively collected glioma tumors. Proteogenomic analysis reveals the downstream biological events leading by EGFR-, IDH1-, TP53-mutations. The comparative analysis illustrates the distinctive features of GBMs and LGGs, indicating CDK2 inhibitor might serve as a promising drug target for GBMs. Further proteogenomic integrative analysis combined with functional experiments highlight the cis-effect of EGFR alterations might lead to glioma tumor cell proliferation through ERK5 medicates nucleotide synthesis process. Proteome-based stratification of gliomas defines 3 proteomic subgroups (S-Ne, S-Pf, S-Im), which could serve as a complement to WHO subtypes, and would provide the essential framework for the utilization of specific targeted therapies for particular glioma subtypes. Immune clustering identifies three immune subtypes with distinctive immune cell types. Further analysis reveals higher EGFR alteration frequencies accounts for elevation of immune check point protein: PD-L1 and CD70 in T-cell infiltrated tumors.

Bioinformatics analysis of miRNAs in the neuroblastoma 11q-deleted region reveals a role of miR-548l in both 11q-deleted and MYCN amplified tumour cells

Neuroblastoma is a childhood tumour that is responsible for approximately 15% of all childhood cancer deaths. Neuroblastoma tumours with amplification of the oncogene MYCN are aggressive, however, another aggressive subgroup without MYCN amplification also exists; rather, they have a deleted region at chromosome arm 11q. Twenty-six miRNAs are located within the breakpoint region of chromosome 11q and have been checked for a possible involvement in development of neuroblastoma due to the genomic alteration. Target genes of these miRNAs are involved in pathways associated with cancer, including proliferation, apoptosis and DNA repair. We could show that miR-548l found within the 11q region is downregulated in neuroblastoma cell lines with 11q deletion or MYCN amplification. In addition, we showed that the restoration of miR-548l level in a neuroblastoma cell line led to a decreased proliferation of these cells as well as a decrease in the percentage of cells in the S phase. We also found that miR-548l overexpression suppressed cell viability and promoted apoptosis, while miR-548l knockdown promoted cell viability and inhibited apoptosis in neuroblastoma cells. Our results indicate that 11q-deleted neuroblastoma and MYCN amplified neuroblastoma coalesce by downregulating miR-548l.

Lengthening the Guanidine-Aryl Linker of Phenylpyrimidinylguanidines Increases Their Potency as Inhibitors of FOXO3-Induced Gene Transcription

Increased FOXO3 nuclear localization is involved in neuroblastoma chemoresistance and tumor angiogenesis. Accordingly, FOXO3 inhibition is a promising strategy for boosting antitumor immune responses and suppressing FOXO3-mediated therapy resistance in cancer cells. However, no FOXO3 inhibitors are currently available for clinical use. Nevertheless, we have recently identified (4-propoxy)phenylpyrimidinylguanidine as a FOXO3 inhibitor in cancer cells in the low micromolar range. Here, we report the synthesis and structure-activity relationship study of a small library of its derivatives, some of which inhibit FOXO3-induced gene transcription in cancer cells in a submicromolar range and are thus 1 order of magnitude more potent than their parent compound. By NMR and molecular docking, we showed that these compounds differ in their interactions with the DNA-binding domain of FOXO3. These results may provide a foundation for further optimizing (4-propoxy)phenylpyrimidinylguanidine and developing therapeutics for inhibiting the activity of forkhead box (FOX) transcription factors and their interactions with other binding partners.

FOXO4 interacts with p53 TAD and CRD and inhibits its binding to DNA

Transcription factor p53 protects cells against tumorigenesis when subjected to various cellular stresses. Under these conditions, p53 interacts with transcription factor Forkhead box O (FOXO) 4, thereby inducing cellular senescence by upregulating the transcription of senescence-associated protein p21. However, the structural details of this interaction remain unclear. Here, we characterize the interaction between p53 and FOXO4 by NMR, chemical cross-linking, and analytical ultracentrifugation. Our results reveal that the interaction between p53 TAD and the FOXO4 Forkhead domain is essential for the overall stability of the p53:FOXO4 complex. Furthermore, contacts involving the N-terminal segment of FOXO4, the C-terminal negative regulatory domain of p53 and the DNA-binding domains of both proteins stabilize the complex, whose formation blocks p53 binding to DNA but without affecting the DNA-binding properties of FOXO4. Therefore, our structural findings may help to understand the intertwined functions of p53 and FOXO4 in cellular homeostasis, longevity, and stress response.

3D bioprinted, vascularized neuroblastoma tumor environment in fluidic chip devices for precision medicine drug testing

Neuroblastoma is an extracranial solid tumor which develops in early childhood and still has a poor prognosis. One strategy to increase cure rates is the identification of patient-specific drug responses in tissue models that mimic the interaction between patient cancer cells and tumor environment. We therefore developed a perfused and micro-vascularized tumor-environment model that is directly bioprinted into custom-manufactured fluidic chips. A gelatin-methacrylate/fibrin-based matrix containing multiple cell types mimics the tumor-microenvironment that promotes spontaneous micro-vessel formation by embedded endothelial cells. We demonstrate that both, adipocyte- and iPSC-derived mesenchymal stem cells can guide this process. Bioprinted channels are coated with endothelial cells post printing to form a dense vessel - tissue barrier. The tissue model thereby mimics structure and function of human soft tissue with endothelial cell-coated larger vessels for perfusion and micro-vessel networks within the hydrogel-matrix. Patient-derived neuroblastoma spheroids are added to the matrix during the printing process and grown for more than two weeks. We demonstrate that micro-vessels are attracted by and grow into tumor spheroids and that neuroblastoma cells invade the tumor-environment as soon as the spheroids disrupt. In summary, we describe the first bioprinted, micro-vascularized neuroblastoma - tumor-environment model directly printed into fluidic chips and a novel medium-throughput biofabrication platform suitable for studying tumor angiogenesis and metastasis in precision medicine approaches in future.

Pre-conceptional and prenatal exposure to pesticides and pediatric neuroblastoma. A meta-analysis of nine studies

Neuroblastoma is primarily an embryonal tumor of infancy. Recently, some toxicological agents used as pesticides have been associated with an increased incidence of this tumor. We intended to determine the potential association between prenatal exposure to pesticides and the incidence of neuroblastoma in children. Studies targeting the link between neuroblastoma and pesticides were searched in PUBMED, SCOPUS, and Google Scholar from January 1, 1960, through December 2020. We performed a PRISMA-based systematic review and meta-analysis. In addition, we took into consideration the IARC evaluation on pesticides issued in recent monographs. Prenatal pesticide exposure is associated with an increased risk of neuroblastoma with an OR of 1.6 (1.1-2.3; p = 0.013), while the OR is 1.0 (0.8-1.3; p = 0.723) for pesticide exposure after birth. There is a significant association between prenatal pesticide exposure and neuroblastoma. We emphasize the IARC conclusions evaluating the carcinogenicity of diazinon, glyphosate, malathion, parathion, and tetrachlorvinphos.

Microvascular Experimentation in the Chick Chorioallantoic Membrane as a Model for Screening Angiogenic Agents including from Gene-Modified Cells

The chick chorioallantoic membrane (CAM) assay model of angiogenesis has been highlighted as a relatively quick, low cost and effective model for the study of pro-angiogenic and anti-angiogenic factors. The chick CAM is a highly vascularised extraembryonic membrane which functions for gas exchange, nutrient exchange and waste removal for the growing chick embryo. It is beneficial as it can function as a treatment screening tool, which bridges the gap between cell based in vitro studies and in vivo animal experimentation. In this review, we explore the benefits and drawbacks of the CAM assay to study microcirculation, by the investigation of each distinct stage of the CAM assay procedure, including cultivation techniques, treatment applications and methods of determining an angiogenic response using this assay. We detail the angiogenic effect of treatments, including drugs, metabolites, genes and cells used in conjunction with the CAM assay, while also highlighting the testing of genetically modified cells. We also present a detailed exploration of the advantages and limitations of different CAM analysis techniques, including visual assessment, histological and molecular analysis along with vascular casting methods and live blood flow observations.

Bioprinted Cancer Model of Neuroblastoma in a Renal Microenvironment as an Efficiently Applicable Drug Testing Platform

Development of new anticancer drugs with currently available animal models is hampered by the fact that human cancer cells are embedded in an animal-derived environment. Neuroblastoma is the most common extracranial solid malignancy of childhood. Major obstacles include managing chemotherapy-resistant relapses and resistance to induction therapy, leading to early death in very-high-risk patients. Here, we present a three-dimensional (3D) model for neuroblastoma composed of IMR-32 cells with amplified genes of the myelocytomatosis viral related oncogene MYCN and the anaplastic lymphoma kinase (ALK) in a renal environment of exclusively human origin, made of human embryonic kidney 293 cells and primary human kidney fibroblasts. The model was produced with two pneumatic extrusion printheads using a commercially available bioprinter. Two drugs were exemplarily tested in this model: While the histone deacetylase inhibitor panobinostat selectively killed the cancer cells by apoptosis induction but did not affect renal cells in the therapeutically effective concentration range, the peptidyl nucleoside antibiotic blasticidin induced cell death in both cell types. Importantly, differences in sensitivity between two-dimensional (2D) and 3D cultures were cell-type specific, making the therapeutic window broader in the bioprinted model and demonstrating the value of studying anticancer drugs in human 3D models. Altogether, this cancer model allows testing cytotoxicity and tumor selectivity of new anticancer drugs, and the open scaffold design enables the free exchange of tumor and microenvironment by any cell type.

Diverse roles of FOXO family members in gastric cancer

Gastric cancer (GC) is the fifth most diagnosed cancer and the third leading cause of cancer-related death worldwide. Although progress has been made in diagnosis, surgical resection, systemic chemotherapy, and immunotherapy, patients with GC still have a poor prognosis. The overall 5-year survival rate in patients with advanced GC is less than 5%. The FOXO subfamily, of the forkhead box family of transcription factors, consists of four members, FOXO1, FOXO3, FOXO4, and FOXO6. This subfamily plays an important role in many cellular processes, such as cell cycle, cell growth, apoptosis, autophagy, stress resistance, protection from aggregate toxicity, DNA repair, tumor suppression, and metabolism, in both normal tissue and malignant tumors. Various studies support a role for FOXOs as tumor suppressors based on their ability to inhibit angiogenesis and metastasis, and promote apoptosis, yet several other studies have shown that FOXOs might also promote tumor progression in certain circumstances. To elucidate the diverse roles of FOXOs in GC, this article systematically reviews the cellular functions of FOXOs in GC to determine potential therapeutic targets and treatment strategies for patients with GC.

Combining Angiogenesis Inhibitors with Radiation: Advances and Challenges in Cancer Treatment

BACKGROUND

Radiation therapy is a widely employed modality that is used to destroy cancer cells, but it also tends to induce changes in the tumor microenvironment and promote angiogenesis. Radiation, when used as a sole means of therapeutic approach to treat cancer, tends to trigger the angiogenic pathways, leading to the upregulation of several angiogenic growth factors such as VEGF, bFGF, PDGF and angiogenin. This uncontrolled angiogenesis leads to certain angiogenic disorders like vascular outgrowth and an increase in tumor progression that can pose a serious threat to patients.

OBJECTIVE

This review emphasizes on various components of the tumor microenvironment, angiogenic growth factors and biological effects of radiation on tumors in provoking the relapse. It also describes the angiogenic mechanisms that trigger the tumor relapse after radiation therapy and how angiogenesis inhibitors can help in overcoming this phenomenon. It gives an overview of various angiogenesis inhibitors in pre-clinical as well as in clinical trials.

CONCLUSION

The review focuses on the beneficial effects of the combinatorial therapeutic approach of anti-angiogenesis therapy and radiation in tumor management.

The evolving landscape of N6-methyladenosine modification in the tumor microenvironment

The tumor microenvironment (TME), controlled by intrinsic mechanisms of carcinogenesis and epigenetic modifications, has, in recent years, become a heavily researched topic. The TME can be described in terms of hypoxia, metabolic dysregulation, immune escape, and chronic inflammation. RNA methylation, an epigenetic modification, has recently been found to have a pivotal role in shaping the TME. The N⁶-methylation of adenosine (m⁶A) modification is the most common type of RNA methylation that occurs in the N⁶-position of adenosine, which is the primary internal modification of eukaryotic mRNA. Compelling evidence has demonstrated that m⁶A regulates transcriptional and protein expression through splicing, translation, degradation, and export, thereby mediating the biological processes of cancer cells and/or stromal cells and characterizing the TME. The TME also has a crucial role in the complicated regulatory network of m⁶A modifications and, subsequently, influences tumor initiation, progression, and therapy responses. In this review, we describe the features of the TME and how the m⁶A modification modulates and interacts with it. We also focus on various factors and pathways involved in m⁶A methylation. Finally, we discuss potential therapeutic strategies and prognostic biomarkers with respect to the TME and m⁶A modification.

Role of FOXO Transcription Factors in Cancer Metabolism and Angiogenesis

Forkhead box O transcription factors (FOXOs) regulate several signaling pathways and play crucial roles in health and disease. FOXOs are key regulators of the expression of genes involved in multiple cellular processes and their deregulation has been implicated in cancer. FOXOs are generally considered tumor suppressors and evidence also suggests that they may have a role in the regulation of cancer metabolism and angiogenesis. In order to continue growing and proliferating, tumor cells have to reprogram their metabolism and induce angiogenesis. Angiogenesis refers to the process of new blood capillary formation from pre-existing vessels, which is an essential driving force in cancer progression and metastasis through supplying tumor cells with oxygen and nutrients. This review summarizes the roles of FOXOs in the regulation of cancer metabolism and angiogenesis. A deeper knowledge of the involvement of FOXOs in these two key processes involved in cancer dissemination may help to develop novel therapeutic approaches for cancer treatment.

The PI3K pathway impacts stem gene expression in a set of glioblastoma cell lines

BACKGROUND

The PI3K pathway controls diverse cellular processes including growth, survival, metabolism, and apoptosis. Nuclear FOXO factors were observed in cancers that harbor constitutively active PI3K pathway output and stem signatures. FOXO1 and FOXO3 were previously published to induce stem genes such as OCT4 in embryonic stem cells. Here, we investigated FOXO-driven stem gene expression in U87MG glioblastoma cells.

METHODS

PI3K-activated cancer cell lines were investigated for changes in gene expression, signal transduction, and clonogenicity under conditions with FOXO3 disruption or exogenous expression. The impact of PI3K pathway inhibition on stem gene expression was examined in a set of glioblastoma cell lines.

RESULTS

We found that CRISPR-Cas9-mediated FOXO3 disruption in U87MG cells caused decreased OCT4 and SOX2 gene expression, STAT3 phosphorylation on tyrosine 705 and clonogenicity. FOXO3 over expression led to increased OCT4 in numerous glioblastoma cancer cell lines. Strikingly, treatment of glioblastoma cells with NVP-BEZ235 (a dual inhibitor of PI3K and mTOR), which activates FOXO factors, led to robust increases OCT4 gene expression. Direct FOXO factor recruitment to the OCT4 promoter was detected by chromatin immunoprecipitation analyses using U87MG extracts.

DISCUSSION

We show for the first time that FOXO transcription factors promote stem gene expression glioblastoma cells. Treatment with PI3K inhibitor NVP-BEZ235 led to dramatic increases in stem genes in a set of glioblastoma cell lines.

CONCLUSION

Given that, PI3K inhibitors are actively investigated as targeted cancer therapies, the FOXO-mediated induction of stem genes observed in this study highlights a potential hazard to PI3K inhibition. Understanding the molecular underpinnings of stem signatures in cancer will allow refinements to therapeutic strategies. Targeting FOXO factors to reduce stem cell characteristics in concert with PI3K inhibition may prove therapeutically efficacious.

Repaglinide Silences the FOXO3/Lumican Axis and Represses the Associated Metastatic Potential of Neuronal Cancer Cells

The transcription factor FOXO3 is associated with poor outcome in high-stage neuroblastoma (NB), as it facilitates chemoprotection and tumor angiogenesis. In other tumor entities, FOXO3 stimulates metastasis formation, one of the biggest challenges in the treatment of aggressive NB. However, the impact of FOXO3 on the metastatic potential of neuronal tumor cells remains largely unknown. In the present study, we uncover the small leucine-rich proteoglycan family member lumican (LUM) as a FOXO3-regulated gene that stimulates cellular migration in NB. By a drug-library screen we identified the small molecular weight compound repaglinide (RPG) as a putative FOXO3 inhibitor. Here, we verify that RPG binds to the FOXO3-DNA-binding-domain (DBD) and thereby silences the transcriptional activity of FOXO3. Consistent with the concept that the FOXO3/LUM axis enhances the migratory capacity of aggressive NB cells, we demonstrate that stable knockdown of LUM abrogates the FOXO3-mediated increase in cellular migration. Importantly, FOXO3 inhibition by RPG represses the binding of FOXO3 to the LUM promoter, inhibits FOXO3-mediated LUM RNA and protein expression, and efficiently abrogates FOXO3-triggered cellular “wound healing” as well as spheroid-based 3D-migration. Thus, silencing the FOXO3/LUM axis by the FDA-approved compound RPG represents a promising strategy for novel therapeutic interventions in NB and other FOXO3-dependent tumors.

Prognostic implications of forkhead box protein O1 (FOXO1) and paired box 3 (PAX3) in epithelial ovarian cancer

BACKGROUND

Transcription factors forkhead box protein O1 (FOXO1) and paired box 3 (PAX3) have been reported to play important roles in various cancers. However, their role in epithelial ovarian cancer (EOC) has not been elucidated yet. Therefore, we evaluated the expression and clinical significance of FOXO1 and PAX3 in EOC.

METHODS

Immunohistochemical analyses of FOXO1 and PAX3 in 212 EOCs, 57 borderline ovarian tumors, 153 benign epithelial ovarian tumors, and 79 nonadjacent normal epithelial tissues were performed using tissue microarray. Various clinicopathological variables, including the survival of EOC patients, were compared. In addition, the effect of FOXO1 on cell growth was assessed in EOC cell lines.

RESULTS

FOXO1 and PAX3 protein expression levels were significantly higher in EOC tissues than in nonadjacent normal epithelial tissues, benign tissues, and borderline tumors (all p < 0.001). In EOC tissues, FOXO1 expression was positively correlated with PAX3 expression (Spearman's rho = 0.118, p = 0.149). Multivariate survival analysis revealed that high FOXO1 expression (hazard ratio = 2.77 [95% CI, 1.48-5.18], p = 0.001) could be an independent prognostic factor for overall survival. Most importantly, high expression of both FOXO1 and PAX3 showed a high hazard ratio (4.60 [95% CI, 2.00-10.55], p < 0.001) for overall survival. Also in vitro results demonstrated that knockdown of FOXO1 was associated with decreased cell viability, migration, and colony formation.

CONCLUSIONS

This study revealed that high expression of FOXO1/PAX3 is an indicator of poor prognosis in EOC. Our results suggest the promising potential of FOXO1 and PAX3 as prognostic and therapeutic markers. The possible link between biological functions of FOXO1 and PAX3 in EOC warrants further studies.

Modulating FOXO3 transcriptional activity by small, DBD-binding molecules

FOXO transcription factors are critical regulators of cell homeostasis and steer cell death, differentiation and longevity in mammalian cells. By combined pharmacophore-modeling-based in silico and fluorescence polarization-based screening we identified small molecules that physically interact with the DNA-binding domain (DBD) of FOXO3 and modulate the FOXO3 transcriptional program in human cells. The mode of interaction between compounds and the FOXO3-DBD was assessed via NMR spectroscopy and docking studies. We demonstrate that compounds S9 and its oxalate salt S9OX interfere with FOXO3 target promoter binding, gene transcription and modulate the physiologic program activated by FOXO3 in cancer cells. These small molecules prove the druggability of the FOXO-DBD and provide a structural basis for modulating these important homeostasis regulators in normal and malignant cells.

A drug library screen identifies Carbenoxolone as novel FOXO inhibitor that overcomes FOXO3-mediated chemoprotection in high-stage neuroblastoma

The transcription factor FOXO3 has been associated in different tumor entities with hallmarks of cancer, including metastasis, tumor angiogenesis, maintenance of tumor-initiating stem cells, and drug resistance. In neuroblastoma (NB), we recently demonstrated that nuclear FOXO3 promotes tumor angiogenesis in vivo and chemoresistance in vitro. Hence, inhibiting the transcriptional activity of FOXO3 is a promising therapeutic strategy. However, as no FOXO3 inhibitor is clinically available to date, we used a medium-throughput fluorescence polarization assay (FPA) screening in a drug-repositioning approach to identify compounds that bind to the FOXO3-DNA-binding-domain (DBD). Carbenoxolone (CBX), a glycyrrhetinic acid derivative, was identified as a potential FOXO3-inhibitory compound that binds to the FOXO3-DBD with a binding affinity of 19 µM. Specific interaction of CBX with the FOXO3-DBD was validated by fluorescence-based electrophoretic mobility shift assay (FAM-EMSA). CBX inhibits the transcriptional activity of FOXO3 target genes, as determined by chromatin immunoprecipitation (ChIP), DEPP-, and BIM promoter reporter assays, and real-time RT-PCR analyses. In high-stage NB cells with functional TP53, FOXO3 triggers the expression of SESN3, which increases chemoprotection and cell survival. Importantly, FOXO3 inhibition by CBX treatment at pharmacologically relevant concentrations efficiently repressed FOXO3-mediated SESN3 expression and clonogenic survival and sensitized high-stage NB cells to chemotherapy in a 2D and 3D culture model. Thus, CBX might be a promising novel candidate for the treatment of therapy-resistant high-stage NB and other "FOXO-resistant" cancers.

Anticancer Action and Mechanism of Ergosterol Peroxide from Paecilomyces cicadae Fermentation Broth

Isaria cicadae, a medicinal food fungus, is a fruit from Paecilomyces cicadae. In this study, we purified ergosterol peroxide (EP) from the fermentation broth of P. cicadae and investigated its effects on renal cell carcinoma (RCC) cells, in vitro. EP was purified from P. cicadae fermentation broth. The human RCC cell line 786-0 was used to analyze the anticancer mechanism of EP and inhibit its effect on cancer cell proliferation, in vitro. EP with a validated structure showed a yield rate of 20.1 mg/L and a purity of 96%. EP significantly inhibited RCC cell growth and clone formation in vitro. In addition, EP suppressed the migration and invasion, triggered the apoptosis, and modulated the cell cycle of RCC cells, in a dose-dependent manner. It also downregulated β-catenin expression. EP could be routinely produced through P. cicadae. It fights RCC cells in vitro through multiple mechanisms, including suppressing cell growth, colonization, migration, and invasion, arresting the cell cycle, attenuating β-catenin pathways, and triggering apoptosis.

Autophagy and doxorubicin resistance in cancer

Doxorubicin (DOX), also known as adriamycin, is a DNA topoisomerase II inhibitor and belongs to the family of anthracycline anticancer drugs. DOX is used for the treatment of a wide variety of cancer types. However, resistance among cancer cells has emerged as a major barrier to effective treatment using DOX. Currently, the role of autophagy in cancer resistance to DOX and the mechanisms involved have become one of the areas of intense investigation. More and more preclinical data are being obtained on reversing DOX resistance through modulation of autophagy as one of the promising therapeutic strategies. This review summarizes the recent advances in autophagy-targeting therapies that overcome DOX resistance from in-vitro studies to animal models for exploration of novel delivery systems. In-depth understanding of the mechanisms of autophagy regulation in relation to DOX resistance and development of molecularly targeted autophagy-modulating agents will provide a promising therapeutic strategy for overcoming DOX resistance in cancer treatment.

MicroRNA-223-3p regulates cell chemo-sensitivity by targeting FOXO3 in prostatic cancer

Prostate cancer (PCa) is one of the most common malignant cancers in male and docetaxel is commonly used as an effective chemotherapeutic drug for PCa patients. However, docetaxel resistance inhibits the therapeutic effect of this agent, thus investigating the mechanism of chemoresistance to docetaxel of PCa may help to improve the prognosis of PCa patients. In our present study, we found that miR-223-3p was up-regulated in PCa cell lines (C4-2, LNCap, PC3, DU-145). Transfection with miR-223-3p inhibitor increased chemo-sensitivity to docetaxel and cell apoptosis rate in PCa cells compared with docetaxel + miR-223-3p mock group, especially in DU-145 cells which were more resistant to docetaxel. Bioinformatics study and luciferase reporter assay indicated that FOXO3 was a target of miR-223-3p and the results from western blot suggested that FOXO3 was negatively regulated by miR-223-3p. Further study revealed that up-regulation of FOXO3 by transfection with pCMV-FOXO3 decreased the IC₅₀ values of docetaxel and increased cell apoptosis rate compared with docetaxel + pCMV-vector group, suggesting that overexpressed FOXO3 suppressed cell survival and sensitized PCa cells to docetaxel. Moreover, siRNA-mediated knockdown of FOXO3 abolished the effects of miR-223-3p inhibitor on chemo-sensitivity and apoptosis in PCa cells by increasing chemoresistance and decreasing cell apoptosis rate. Finally, the in vivo experiments showed that miR-223-3p inhibitor sensitized prostatic cancer mouse model to docetaxel by increasing the expression of FOXO3. In conclusion, our present study indicated that miR-223-3p regulated cell chemo-sensitivity by targeting FOXO3 in prostatic cancer both in vitro and in vivo, providing new potential therapeutic strategy for PCa treatment.

FOXO3-mediated chemo-protection in high-stage neuroblastoma depends on wild-type TP53 and SESN3

Forkhead box O class transcription factors are homeostasis regulators that control cell death, longevity and therapy-resistance. In neuroblastoma (NB), nuclear FOXO3 correlates with stage M disease and poor prognosis. To analyze whether FOXO3 contributes to drug-resistance in this childhood cancer, we investigated how different high-stage-derived NB cells respond to the activation of an ectopic FOXO3 allele. We found endogenous FOXO3 mostly localized to the nucleus—upon activation of an ectopic, 4OHT-activated FOXO3(A3)ER fusion protein two of the cell lines underwent apoptosis, whereas in the others FOXO3-activation even increased survival during drug-treatment. In the latter cell type, FOXO3 did not induce the BH3-only protein BCL2L11/BIM due to impaired binding of FOXO3 to the BIM-promoter, but still activated other FOXO3 targets. It was shown before that FOXO3 and TP53 physically interact with each other at two different regions—the TP53-N-terminus binds to the FOXO3-DNA binding domain (DBD) and the FOXO3-C-terminus interacts with the TP53-DBD. Interestingly, cell lines that undergo FOXO3-induced cell death carry homozygous point mutations in the TP53-DBD near the structural hotspot-mutation-site R175H, which abrogated FOXO3–TP53 interaction. In contrast, in FOXO3-death-resistant cells no point mutations in the TP53-DBD were found—in these cells FOXO3–TP53 complexes are formed and FOXO3-binding to the BIM-promoter, but not the induction of the detoxifying protein SESN3, were prevented, which in turn increased chemo-protection in this type of high-stage-derived NB cells. Our combined data suggest that FOXO3 steps in as a death inducer in case of TP53-mutation, whereas functional TP53 alters FOXO3-target-promoter-recognition, which prevents death induction by FOXO3 and instead increases chemo-protection and survival of NB cells. This novel mechanism may explain the low incidence of TP53 mutation in high-stage NB at diagnosis and suggests FOXO3 as a therapeutic target for this childhood malignancy.

C10ORF10/DEPP-mediated ROS accumulation is a critical modulator of FOXO3-induced autophagy

Background

Neuroblastoma is the most common solid tumor in childhood and develops from undifferentiated progenitor cells of the sympathetic nervous system. In neuronal tumor cells DNA-damaging chemotherapeutic agents activate the transcription factor FOXO3 which regulates the formation of reactive oxygen species (ROS) and cell death as well as a longevity program associated with therapy resistance.

We demonstrated before that C10ORF10/DEPP, a transcriptional target of FOXO3, localizes to peroxisomes and mitochondria and impairs cellular ROS detoxification. In the present study, we investigated the impact of FOXO3 and DEPP on the regulation of autophagy. Autophagy serves to reduce oxidative damage as it triggers a self-degradative process for the removal of aggregated or misfolded proteins and damaged organelles.

Methods

The effect of FOXO3 and DEPP on autophagy induction was analyzed using live cell fluorescence microscopy and immunoblot analyses of SH-EP cells transfected with a plasmid for EYFP-LC3 and with siRNAs specific for LC3, respectively. ROS steady-state levels were measured with reduced MitoTrackerRed CM-H2XROS. Cellular apoptosis was analyzed by flow cytometry and the caspase 3/7 assay.

Results

We report for the first time that DEPP induces ROS accumulation and thereby mediates the formation of autophagosomes as inhibition of ROS formation by N-acetyl-cysteine completely blocks autophagy. We further demonstrate that H₂O₂-treatment triggers autophagy-induction by FOXO3-mediated DEPP expression. Importantly, knockdown of DEPP was sufficient to efficiently inhibit autophagy-induction under different stress conditions such as serum starvation and genotoxic stress, suggesting that DEPP expression is critical for the initiation of autophagy in neuroblastoma. FOXO3-triggered autophagy partially protects neuroblastoma cells from cell death. Consistent with this concept, we demonstrate that inhibition of autophagy by LC3-knockdown significantly increased etoposide- and doxorubicin-induced apoptosis. These results were also confirmed by the use of the autophagy-inhibitor chloroquine that significantly enhanced the chemotherapeutic effect of etoposide and doxorubicin in neuronal tumor cells.

Conclusion

Targeting FOXO3/DEPP-triggered autophagy is a promising strategy to sensitize neuroblastoma cells to chemotherapy.

Electronic supplementary material

The online version of this article (doi:10.1186/s12943-017-0661-4) contains supplementary material, which is available to authorized users.