Multidrug resistance in pediatric oncology

Eicosapentaenoic acid enhances the sensitivity of osteosarcoma to cisplatin by inducing ferroptosis through the DNA-PKcs/AKT/NRF2 pathway and reducing PD-L1 expression to attenuate immune evasion

Acquired drug resistance poses a significant challenge in osteosarcoma therapy. Therefore, it is necessary for us to discover and develop an alternative anti-cancer strategy. Previous studies have shown that eicosapentaenoic acid (EPA) significantly increases chemosensitivity in cancer cells. In this study, we discovered that EPA enhances the sensitivity of osteosarcoma to cisplatin (DDP). Interestingly, in addition to inhibiting growth and inducing apoptosis, EPA also enhances DDP-induced ferroptosis. Western blot analysis confirmed that EPA treatment significantly decreases the expression of DNA-dependent protein kinase catalytic subunit (DNA-PKcs), p-AKT, nuclear factor erythroid 2-related factor 2 (NRF2), and glutathione peroxidase 4 (GPX4) in cells. Knockdown of DNA-PKcs by siRNA further enhances the level of ferroptosis induced by EPA. Importantly, EPA can reverse the high expression level of programmed death ligand 1 (PD-L1) induced by DDP. ELISA and western blotting analysis revealed that EPA treatment decreases the levels of IL-6 and p-STAT3, which are increased by DDP treatment. Furthermore, a co-immunoprecipitation (co-IP) assay confirmed the interaction between DNA-PKcs and PD-L1, and knockdown of DNA-PKcs further reduces the expression of PD-L1. This data provides the first evidence that EPA suppresses the DNA-PKcs/AKT/NRF2/GPX4 pathway to enhance ferroptosis, and inhibits IL-6/STAT3 and DNA-PKcs to decrease PD-L1 expression, thereby sensitizing osteosarcoma to DDP. The combination of EPA and DDP presents an encouraging and promising anti-tumor strategy.

microRNA-216b enhances cisplatin-induced apoptosis in osteosarcoma MG63 and SaOS-2 cells by binding to JMJD2C and regulating the HIF1α/HES1 signaling axis

Background

Although cisplatin-based chemotherapy represents the standard regimen for osteosarcoma (OS), OS patients often exhibit treatment failure and poor prognosis due to chemoresistance to cisplatin. Emerging research has highlighted the tumor suppressive properties of microRNAs (miRNAs or miRs) in various human cancers via the inhibition of the histone demethylase jumonji domain containing protein 2C (JMJD2C). As a coactivator for hypoxia-inducible factor 1α (HIF1α), JMJD2C targets hairy and enhancer of split-1 (HES1) gene. Hence, the current study aimed to elucidate the role of miR-216b in OS cell cisplatin resistance to identify the underlying mechanism of miR-216b regulating the JMJD2C//HIF1α/HES1 signaling.

Methods

Tumor and paracancerous tissues were collected from OS patients to determine the expression patterns of miR-216b and JMJD2C. After ectopic expression and knockdown experiments in the OS cells, CCK-8 assay and flow cytometry were employed to determine cell viability and apoptosis. The interaction of miR-216b, JMJD2C, HIF1α and HES1 was subsequently determined by dual luciferase reporter, co-immunoprecipitation (IP) and ChIP-qPCR assays. In vivo experiments were conducted to further verify the role of the miR-216b in the resistance of OS cells to cisplatin.

Results

miR-216b expression was reduced in the OS tissues, as well as the MG63 and SaOS-2 cells. Heightened miR-216b expression was found to be positively correlated with patient survival, and miR-216b further enhanced cisplatin-induced apoptosis of MG63 and SaOS-2 cells. Mechanistically, miR-216b inhibited JMJD2C expression by binding to its 3’UTR. Through interaction with HIF1α, JMJD2C removed the H3K9 methylation modification at the HES1 promoter region, leading to upregulation of HES1 in vitro. Furthermore, miR-216b was observed to increase the tumor growth in nude mice in the presence of cisplatin treatment. HES1 overexpression weakened the effects of miR-216b in MG63 and SaOS-2 cells and in nude mouse xenografts.

Conclusion

Overall, miR-216b enhanced the sensitivity of OS cells to cisplatin via downregulation of the JMJD2C/HIF1α/HES1 signaling axis, highlighting the capacity of miR-216b as an adjunct to cisplatin chemotherapy in the treatment of OS.

Overcoming Wnt-β-catenin dependent anticancer therapy resistance in leukaemia stem cells

Leukaemia stem cells (LSCs) underlie cancer therapy resistance but targeting these cells remains difficult. The Wnt-β-catenin and PI3K-Akt pathways cooperate to promote tumorigenesis and resistance to therapy. In a mouse model in which both pathways are activated in stem and progenitor cells, LSCs expanded under chemotherapy-induced stress. Since Akt can activate β-catenin, inhibiting this interaction might target therapy-resistant LSCs. High-throughput screening identified doxorubicin (DXR) as an inhibitor of the Akt-β-catenin interaction at low doses. Here we repurposed DXR as a targeted inhibitor rather than a broadly cytotoxic chemotherapy. Targeted DXR reduced Akt-activated β-catenin levels in chemoresistant LSCs and reduced LSC tumorigenic activity. Mechanistically, β-catenin binds multiple immune-checkpoint gene loci, and targeted DXR treatment inhibited expression of multiple immune checkpoints specifically in LSCs, including PD-L1, TIM3 and CD24. Overall, LSCs exhibit distinct properties of immune resistance that are reduced by inhibiting Akt-activated β-catenin. These findings suggest a strategy for overcoming cancer therapy resistance and immune escape.

Impact of Age-Related Genetic Differences on the Therapeutic Outcome of Papillary Thyroid Cancer

The incidence of papillary thyroid carcinoma (PTC) has been increasing worldwide. PTC is the most common type of differentiated thyroid cancer and usually shows good prognosis. However, some PTC is driven to advanced stage by epithelial-mesenchymal transition (EMT)-mediated drug resistance, which is particularly noticeable in pediatric patients. There are limited options for systemic treatment, necessitating development of new clinical approaches. Here, we aimed to clarify genetic differences due to age of patients with PTC, and thereby aid in developing novel therapeutics. Patients with biochemically and histologically confirmed PTC were included in this study. PTC cells were acquired from young and older patients showing drug resistance, and were compared via microarray analysis. Cellular proliferation and other properties were determined after treatments with lenvatinib and sorafenib. In vivo, tumor volume and other properties were examined using a mouse xenograft model. Lenvatinib-treated group showed obvious suppression of markers of anti-apoptosis, EMT, and the FGFR signaling pathway, compared with control and Sorafenib-treated group. In the xenograft models, lenvatinib treatment induced significant tumor shrinkage and blocked the proto-oncogene Bcl-2 (B cell lymphoma/leukemia gene-2) and FGFR signaling pathway, along with reduced levels of EMT markers, compared with control and Sorafenib-treated group. Our findings clarify the age-dependent characteristics of pediatric PTC, giving insights into the relationship between young age and poor prognosis. Furthermore, it provides a basis for developing novel therapeutics tailored to the age at diagnosis.

Targeting Autophagy in ALK-Associated Cancers

Autophagy is an evolutionarily conserved catabolic process, which is used by the cells for cytoplasmic quality control. This process is induced following different kinds of stresses e.g., metabolic, environmental, or therapeutic, and acts, in this framework, as a cell survival mechanism. However, under certain circumstances, autophagy has been associated with cell death. This duality has been extensively reported in solid and hematological cancers, and has been observed during both tumor development and cancer therapy. As autophagy plays a critical role at the crossroads between cell survival and cell death, its involvement and therapeutic modulation (either activation or inhibition) are currently intensively studied in cancer biology, to improve treatments and patient outcomes. Over the last few years, studies have demonstrated the occurrence of autophagy in different Anaplastic Lymphoma Kinase (ALK)-associated cancers, notably ALK-positive anaplastic large cell lymphoma (ALCL), non-small cell lung carcinoma (NSCLC), Neuroblastoma (NB), and Rhabdomyosarcoma (RMS). In this review, we will first briefly describe the autophagic process and how it can lead to opposite outcomes in anti-cancer therapies, and we will then focus on what is currently known regarding autophagy in ALK-associated cancers.

Crizotinib-induced antitumour activity in human alveolar rhabdomyosarcoma cells is not solely dependent on ALK and MET inhibition

Background

Rhabdomyosarcoma (RMS) is the most commonly diagnosed malignant soft tissue tumour in children and adolescents. Aberrant expression of Anaplastic Lymphoma Kinase (ALK) and MET gene has been implicated in the malignant progression of RMS, especially in the alveolar subtype. This observation suggests that crizotinib (PF-02341066), a kinase inhibitor against ALK and MET, may have a therapeutic role in RMS, although its antitumour activity in this malignancy has not yet been studied.

Methods

RH4 and RH30 alveolar RMS (ARMS) cell lines were treated with crizotinib and then assessed by using proliferation, viability, migration and colony formation assays. Multiple approaches, including flow cytometry, immunofluorescence, western blotting and siRNA-based knock-down, were used in order to investigate possible molecular mechanisms linked to crizotinib activity.

Results

In vitro treatment with crizotinib inhibited ALK and MET proteins, as well as Insulin-like Growth Factor 1 Receptor (IGF1R), with a concomitant robust dephosphorylation of AKT and ERK, two downstream kinases involved in RMS cell proliferation and survival. Exposure to crizotinib impaired cell growth, and accumulation at G2/M phase was attributed to an altered expression and activation of checkpoint regulators, such as Cyclin B1 and Cdc2. Crizotinib was able to induce apoptosis and autophagy in a dose-dependent manner, as shown by caspase-3 activation/PARP proteolytic cleavage down-regulation and by LC3 activation/p62 down-regulation, respectively. The accumulation of reactive oxygen species (ROS) seemed to contribute to crizotinib effects in RH4 and RH30 cells. Moreover, crizotinib-treated RH4 and RH30 cells exhibited a decreased migratory/invasive capacity and clonogenic potential.

Conclusions

These results provide a further insight into the molecular mechanisms affected by crizotinib in ARMS cells inferring that it could be a useful therapeutic tool in ARMS cancer treatment.

Electronic supplementary material

The online version of this article (doi:10.1186/s13046-015-0228-4) contains supplementary material, which is available to authorized users.

Phase II evaluation of intravenous vinorelbine (Navelbine) in recurrent or refractory pediatric malignancies: a Children's Oncology Group study

BACKGROUND

A Phase II trial was developed to determine the efficacy and toxicity of intravenous vinorelbine, a semi-synthetic vinca alkaloid, in children, adolescent, and young adults with recurrent or refractory solid malignancies.

PROCEDURES

Fifty patients were enrolled among three strata: soft tissue sarcomas [rhabdomyosarcoma (RMS), non-rhabdomyosarcoma, primitive neuroepithelial tumor] (20 patients); brain tumors [astrocytoma (4 patients), medulloblastoma (2 patients), other (16 patients)] (22 patients); neuroblastoma (8 patients). Vinorelbine was given weekly for 6 consecutive weeks during an 8-week interval. The response rate and toxicity profile was assessed.

RESULTS

Among the first 35 patients treated at 33.75 mg/m(2)/dose, 25 experienced grades 3-4 neutropenia (75%). The dose was decreased to 30 mg/m(2)/dose in the remaining 15 patients. The median age was 10 years (range, 1-25). Four responses (one complete, three partial) occurred within the soft tissue sarcoma strata (all with RMS) and two occurred in the brain tumor group (medulloblastoma and astrocytoma). The most common toxicities were hematological and neurological.

CONCLUSION

Vinorelbine at dose of 30 mg/m(2) can be safely administered to children with recurrent or refractory solid malignancies. The study design identified vinorelbine to be active in the sarcoma category, with a response rate of 36% (4/11) among RMS patients.

Ornithine decarboxylase inhibition by alpha-difluoromethylornithine activates opposing signaling pathways via phosphorylation of both Akt/protein kinase B and p27Kip1 in neuroblastoma

Ornithine decarboxylase (ODC) is a key enzyme in mammalian polyamine biosynthesis that is up-regulated in various types of cancer. We previously showed that treating human neuroblastoma (NB) cells with the ODC inhibitor alpha-difluoromethylornithine (DFMO) depleted polyamine pools and induced G1 cell cycle arrest without causing apoptosis. However, the precise mechanism by which DFMO provokes these changes in NB cells remained unknown. Therefore, we further examined the effects of DFMO, alone and in combination with phosphatidylinositol 3-kinase (PI3K) inhibitor LY294002 or Akt/protein kinase B (PKB) inhibitor IV, on the regulation of cell survival and cell cycle-associated pathways in LAN-1 NB cells. In the present study, we found that the inhibition of ODC by DFMO promotes cell survival by inducing the phosphorylation of Akt/PKB at residue Ser473 and glycogen synthase kinase-3beta at Ser9. Intriguingly, DFMO also induced the phosphorylation of p27Kip1 at residues Ser10 (nuclear export) and Thr198 (protein stabilization) but not Thr187 (proteasomal degradation). The combined results from this study provide evidence for a direct cross-talk between ODC-dependent metabolic processes and well-established cell signaling pathways that are activated during NB tumorigenesis. The data suggest that inhibition of ODC by DFMO induces two opposing pathways in NB: one promoting cell survival by activating Akt/PKB via the PI3K/Akt pathway and one inducing p27Kip1/retinoblastoma-coupled G1 cell cycle arrest via a mechanism that regulates the phosphorylation and stabilization of p27Kip1. This study presents new information that may explain the moderate efficacy of DFMO monotherapy in clinical trials and reveals potential new targets for DFMO-based combination therapies for NB treatment.

Sorafenib inhibits tumor growth and vascularization of rhabdomyosarcoma cells by blocking IGF-1R-mediated signaling

The growth of many soft tissue sarcomas is dependent on aberrant growth factor signaling, which promotes their proliferation and motility. With this in mind, we evaluated the effect of sorafenib, a receptor tyrosine kinase inhibitor, on cell growth and apoptosis in sarcoma cell lines of various histological subtypes. We found that sorafenib effectively inhibited cell proliferation in rhabdomyosarcoma, synovial sarcoma and Ewing’s sarcoma with IC₅₀ values <5 μM. Sorafenib effectively induced growth arrest in rhabdomyosarcoma cells, which was concurrent with inhibition of Akt and Erk signaling. Studies of ligand-induced phosphorylation of Erk and Akt in rhabdomyosarcoma cells showed that insulin-like growth factor-1 is a potent activator, which can be blocked by treatment with sorafenib. In vivo sorafenib treatment of rhabdomyosarcoma xenografts had a significant inhibitory effect on tumor growth, which was associated with inhibited vascularization and enhanced necrosis in the adjacent tumor stroma. Our results demonstrate that in vitro and in vivo growth of rhabdomyosarcoma can be suppressed by treatment with sorafenib, and suggests the possibilities of using sorafenib as a potential adjuvant therapy for the treatment of rhabdomyosarcoma.

MDR1 modulators improve the chemotherapy response of human hepatoblastoma to doxorubicin in vitro

PURPOSE

P-glycoprotein, a membrane efflux pump encoded by the MDR1 gene, plays an important role in the development of multidrug resistance in human hepatoblastoma (HB). Chemosensitizers antagonize the efflux action of P-glycoprotein. This study investigates the effects of 3 chemosensitizers (the cyclosporin analogue SDZ PSC 833 (PSC 833), the acridone carboxamide derivative GG 918, and verapamil) on the chemotherapy of HB in vitro.

METHODS

The doxorubicin (DOXO) concentration that produces 50% growth inhibition (IC50) in a HB cell line was determined and additional effects of PSC 833, GG 918, and verapamil were investigated in a cytotoxicity assay. The MDR1 gene expression after treatment was determined in a semiquantitative reverse transcription polymerase chain reaction approach.

RESULTS

The IC50 of DOXO is 2.5 microg/mL, 0.61 microg/mL for DOXO + PSC 833, 1.17 microg/mL for DOXO + verapamil, and 1.47 microg/mL for DOXO + GG 918. In combination with DOXO, cell growth was inhibited 4.1-fold by PSC 833, 2.1-fold by verapamil, and 1.9-fold by GG 918. The MDR1 gene expression was enhanced significantly in all treated cells, with and without modulator.

CONCLUSIONS

MDR1 modulators significantly improve the response of HB to DOXO in vitro. The combination of anticancer agents and MDR1 modulators might be a possible contribution to overcome multidrug resistance in HB.

Sphingolipids in neuroblastoma: their role in drug resistance mechanisms

Disseminated neuroblastoma usually calls for chemotherapy as the primary approach for treatment. Treatment failure is often attributable to drug resistance. This involves a variety of cellular mechanisms, including increased drug efflux through expression of ATP-binding cassette transporters (e.g., P-glycoprotein) and the inability of tumor cells to activate or propagate the apoptotic response. In recent years it has become apparent that sphingolipid metabolism and the generation of sphingolipid species, such as ceramide, also play a role in drug resistance. This may involve an autonomous mechanism, related to direct effects of sphingolipids on the apoptotic response, but also a subtle interplay between sphingolipids and ATP-binding cassette transporters. Here, we present an overview of the current understanding of the multiple levels at which sphingolipids function in drug resistance, with an emphasis on sphingolipid function in neuroblastoma and how modulation of sphingolipid metabolism may be used as a novel treatment paradigm.

Pharmacokinetic interactions of cyclosporine with etoposide and mitoxantrone in children with acute myeloid leukemia

The purpose of this study was to assess the effect of the multidrug resistance modulator cyclosporine (CsA) on the pharmacokinetics of etoposide and mitoxantrone in children with de novo acute myeloid leukemia (AML). Serial blood samples for pharmacokinetic studies were obtained in 38 children over a 24-h period following cytotoxin treatment with or without CsA on days 1 and 4. Drug concentrations were quantitated using validated HPLC methods, and pharmacokinetic parameters were determined using compartmental modeling with an iterative two-stage approach, implemented on ADAPT II software. Etoposide displayed a greater degree of interindividual variability in clearance and systemic exposure than mitoxantrone. With CsA treatment, etoposide and mitoxantrone mean clearance declined by 71% and 42%, respectively. These effects on clearance, in combination with the empiric 40% dose reduction for either cytotoxin, resulted in a 47% and 12% increases in the mean AUC for etoposide and mitoxantrone, respectively. There were no differences in the rates of stomatitis or infection between the two groups. CsA treatment resulted in an increased incidence of hyperbilrubinemia, which rapidly reversed upon conclusion of drug therapy. The variability observed in clearance, combined with the empiric 40% dose reduction of the cytotoxins, resulted in statistically similar systemic exposure and similar toxicity.

Assessment of chemosensitivity in patients with osteogenic sarcoma using the doxorubicin binding assay

BACKGROUND AND OBJECTIVES

Assessment of chemosensitivity in patients with osteosarcoma may help identify those with resistance to chemotherapy. In this study, we investigated the clinical value of the doxorubicin binding assay in its ability to identify patients with drug resistance.

METHODS

We tested tumor tissue samples obtained at biopsy of 24 patients with high-grade osteosarcoma aged 9-61 years (mean 19.2) for sensitivity to doxorubicin, using the doxorubicin binding assay. Tumor excision was performed in these patients after neoadjuvant chemotherapy. Chemotherapy response was judged on the basis of tumor necrosis achieved and was compared with doxorubicin sensitivity in each of these patients.

RESULTS

Doxorubicin sensitivity was good in 15 and poor in 9 of 24 patients studied. In patients with good sensitivity (n = 15), 9 (60%) exhibited a good response to chemotherapy while response was poor in 6. In patients with poor sensitivity (n = 9), response to chemotherapy was poor in all 9 (100%) patients and 7 (77.8%) of these patients developed metastatic disease within a mean period of 5.2 months, resulting in two deaths. The results were statistically significant at P = 0.0193.

CONCLUSIONS

Doxorubicin binding assay may be useful in identifying patients with inherent resistance to chemotherapy. As the outcome of patients showing resistance to doxorubicin is poor, innovative strategies may need to be developed for this group of patients.

Diagnostics of multidrug resistance in cancer

Multidrug resistance (MDR), caused by the overexpression of two membrane proteins, MDR1-Pgp and/or MRP, is a major obstacle in the chemotherapy of cancer. The proper laboratory diagnosis of clinical multidrug resistance is still an unresolved question, and this uncertainty, in a vicious cycle, does not allow the correct evaluation of the clinical relevance of the MDR phenomenon. More-over, inefficient MDR diagnostics hinders the development of effective resistance-modulation strategies. In this review, after describing the basic features of the MDR drug pump proteins, the currently employed diagnostic methods are discussed. We suggest that a quantitative, functional method developed in our laboratory may provide a major help in the laboratory assessment of cancer MDR.