Mesenchymal stromal cell secretome up-regulates 47 kDa CXCR4 expression, and induce invasiveness in neuroblastoma cell lines

The therapeutic effect of MSCs and their extracellular vesicles on neuroblastoma

Neuroblastoma is a common inflammatory-related cancer during infancy. Standard treatment modalities including surgical interventions, high-dose chemotherapy, radiotherapy, and immunotherapy are not able to increase survival rate and reduce tumor relapse in high-risk patients. Mesenchymal stem cells (MSCs) are known for their tumor-targeting and immunomodulating properties. MSCs could be engineered to express anticancer agents (i.e., growth factors, cytokines, pro-apoptotic agents) or deliver oncolytic viruses in the tumor microenvironment. As many functions of MSCs are mediated through their secretome, researchers have tried to use extracellular vesicles (EVs) from MSCs for targeted therapy of neuroblastoma. Here, we reviewed the studies to figure out whether the use of MSCs could be worthwhile in neuroblastoma therapy or not. Native MSCs have shown a promoting or inhibiting role in cancers including neuroblastoma. Therefore, MSCs are proposed as a vehicle to deliver anticancer agents such as oncolytic viruses to the neuroblastoma tumor microenvironment. Although modified MSCs or their EVs have been shown to suppress the tumorigenesis of neuroblastoma, further pre-clinical and clinical studies are required to come to a conclusion.

Nafamostat mesylate prevents metastasis and dissemination of neuroblastoma through vascular endothelial growth factor inhibition

Neuroblastoma is a highly malignant disease with a poor prognosis and few treatment options. Despite conventional chemotherapy for neuroblastoma, resistance, invasiveness, and metastatic mobility limit the treatment efficacy. Therefore, it is necessary to develop new strategies for treating neuroblastoma. The present study aimed to evaluate the anticancer effects of nafamostat mesylate, a previously known serine protease inhibitor, on neuroblastoma cells. Effects of nafamostat mesylate on neuroblastoma cell migration and proliferation were analyzed by wound healing assay and WST-8 assay, respectively. To elucidate the mechanisms underlying the effects of nafamostat mesylate on neuroblastoma, the expression levels of NF-κB were measured via western blotting, and the production of the cytokine vascular endothelial growth factor (VEGF) in the cell culture supernatants was determined via ELISA. In addition, a mouse model of hematogenous metastasis was used to investigate the effects of nafamostat mesylate on neuroblastoma. It was determined that nafamostat mesylate significantly inhibited migration and invasion of Neuro-2a cells, but it had no effect on cell proliferation at 24 h after treatment. Exposure of Neuro-2a cells to nafamostat mesylate resulted in decreased vascular endothelial growth factor production, which could be a pivotal mechanism underlying the inhibitory effects of neuroblastoma metastasis. The results of the present study suggest that nafamostat mesylate may be an effective treatment against neuroblastoma invasion and metastasis.

Mechanisms, Diagnosis and Treatment of Bone Metastases

Bone and bone marrow are among the most frequent metastatic sites of cancer. The occurrence of bone metastasis is frequently associated with a dismal disease outcome. The prevention and therapy of bone metastases is a priority in the treatment of cancer patients. However, current therapeutic options for patients with bone metastatic disease are limited in efficacy and associated with increased morbidity. Therefore, most current therapies are mainly palliative in nature. A better understanding of the underlying molecular pathways of the bone metastatic process is warranted to develop novel, well-tolerated and more successful treatments for a significant improvement of patients' quality of life and disease outcome. In this review, we provide comparative mechanistic insights into the bone metastatic process of various solid tumors, including pediatric cancers. We also highlight current and innovative approaches to biologically targeted therapy and immunotherapy. In particular, we discuss the role of the bone marrow microenvironment in the attraction, homing, dormancy and outgrowth of metastatic tumor cells and the ensuing therapeutic implications. Multiple signaling pathways have been described to contribute to metastatic spread to the bone of specific cancer entities, with most knowledge derived from the study of breast and prostate cancer. However, it is likely that similar mechanisms are involved in different types of cancer, including multiple myeloma, primary bone sarcomas and neuroblastoma. The metastatic rate-limiting interaction of tumor cells with the various cellular and noncellular components of the bone-marrow niche provides attractive therapeutic targets, which are already partially exploited by novel promising immunotherapies.

Mesenchymal stem cells accelerated growth and metastasis of neuroblastoma and preferentially homed towards both primary and metastatic loci in orthotopic neuroblastoma model

Background

Majority of neuroblastoma patients develop metastatic disease at diagnosis and their prognosis is poor with current therapeutic approach. Major challenges are how to tackle the mechanisms responsible for tumorigenesis and metastasis. Human mesenchymal stem cells (hMSCs) may be actively involved in the constitution of cancer microenvironment.

Methods

An orthotopic neuroblastoma murine model was utilized to mimic the clinical scenario. Human neuroblastoma cell line SK-N-LP was transfected with luciferase gene, which were inoculated with/without hMSCs into the adrenal area of SCID-beige mice. The growth and metastasis of neuroblastoma was observed by using Xenogen IVIS 100 in vivo imaging and evaluating gross tumors ex vivo. The homing of hMSCs towards tumor was analyzed by tracing fluorescence signal tagged on hMSCs using CRI Maestro™ imaging system.

Results

hMSCs mixed with neuroblastoma cells significantly accelerated tumor growth and apparently enhanced metastasis of neuroblastoma in vivo. hMSCs could be recruited by primary tumor and also become part of the tumor microenvironment in the metastatic lesion. The metastatic potential was consistently reduced in lung and tumor when hMSCs were pre-treated with stromal cell derived factor-1 (SDF-1) blocker, AMD3100, suggesting that the SDF-1/CXCR4 axis was one of the prime movers in the metastatic process.

Conclusions

hMSCs accelerated and facilitated tumor formation, growth and metastasis. Furthermore, the homing propensity of hMSCs towards both primary tumor and metastatic loci can also provide new therapeutic insights in utilizing bio-engineered hMSCs as vehicles for targeted anti-cancer therapy.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-021-08090-2.

Neuroblastoma Invasion Strategies Are Regulated by the Extracellular Matrix

Neuroblastoma is a paediatric malignancy of the developing sympathetic nervous system. About half of the patients have metastatic disease at the time of diagnosis and a survival rate of less than 50%. Our understanding of the cellular processes promoting neuroblastoma metastases will be facilitated by the development of appropriate experimental models. In this study, we aimed to explore the invasion of neuroblastoma cells and organoids from patient-derived xenografts (PDXs) grown embedded in 3D extracellular matrix (ECM) hydrogels by time-lapse microscopy and quantitative image analysis. We found that the ECM composition influenced the growth, viability and local invasion of organoids. The ECM compositions induced distinct cell behaviours, with Matrigel being the preferred substratum for local organoid invasion. Organoid invasion was cell line- and PDX-dependent. We identified six distinct phenotypes in PDX-derived organoids. In contrast, NB cell lines were more phenotypically restricted in their invasion strategies, as organoids isolated from cell line-derived xenografts displayed a broader range of phenotypes compared to clonal cell line clusters. The addition of FBS and bFGF induced more aggressive cell behaviour and a broader range of phenotypes. In contrast, the repression of the prognostic neuroblastoma marker, MYCN, resulted in less aggressive cell behaviour. The combination of PDX organoids, real-time imaging and the novel 3D culture assays developed herein will enable rapid progress in elucidating the molecular mechanisms that control neuroblastoma invasion.

Mesenchymal Stromal Cells in Neuroblastoma: Exploring Crosstalk and Therapeutic Implications

Neuroblastoma (NB) is the second most common solid cancer in childhood, accounting for 15% of cancer-related deaths in children. In high-risk NB patients, the majority suffers from metastasis. Despite intensive multimodal treatment, long-term survival remains <40%. The bone marrow (BM) is among the most common sites of distant metastasis in patients with high-risk NB. In this environment, small populations of tumor cells can persist after treatment (minimal residual disease) and induce relapse. Therapy resistance of these residual tumor cells in BM remains a major obstacle for the cure of NB. A detailed understanding of the microenvironment and its role in tumor progression is of utmost importance for improving the treatment efficiency of NB. In BM, mesenchymal stromal cells (MSCs) constitute an important part of the microenvironment, where they support hematopoiesis and modulate immune responses. Their role in tumor progression is not completely understood, especially for NB. Although MSCs have been found to promote epithelial-mesenchymal transition, tumor growth, and metastasis and to induce chemoresistance, some reports point toward a tumor-suppressive effect of MSCs. In this review, we aim to compile current knowledge about the role of MSCs in NB development and progression. We evaluate arguments that depict tumor-supportive versus -suppressive properties of MSCs in the context of NB and give an overview of factors involved in MSC-NB crosstalk. A focus lies on the BM as a metastatic niche, since that is the predominant site for NB metastasis and relapse. Finally, we will present opportunities and challenges for therapeutic targeting of MSCs in the BM microenvironment.

The Metastatic Bone Marrow Niche in Neuroblastoma: Altered Phenotype and Function of Mesenchymal Stromal Cells

Background: The bone marrow (BM) is the main site of metastases and relapse in patients with neuroblastoma (NB). BM-residing mesenchymal stromal cells (MSCs) were shown to promote tumor cell survival and chemoresistance. Here we characterize the MSC compartment of the metastatic NB BM niche. Methods: Fresh BM of 62 NB patients (all stages), and control fetal and adult BM were studied by flow cytometry using well-established MSC-markers (CD34-, CD45-, CD90+, CD105+), and CD146 and CD271 subtype-markers. FACS-sorted BM MSCs and tumor cells were validated by qPCR. Moreover, isolated MSCs were tested for multilineage differentiation and Colony-forming-unit-fibroblasts (CFU-Fs) capacity. Results: Metastatic BM contains a higher number of MSCs (p < 0.05) with increased differentiation capacity towards the osteoblast lineage. Diagnostic BM contains a MSC-subtype (CD146+CD271-), only detected in BM of patients with metastatic-NB, determined by flow cytometry. FACS-sorting clearly discriminated MSC(-subtypes) and NB fractions, validated by mRNA and DNA qPCR. Overall, the CD146+CD271- subtype decreased during therapy and was detected again in the majority of patients at relapse. Conclusions: We demonstrate that the neuroblastoma BM-MSC compartment is different in quantity and functionality and contains a metastatic-niche-specific MSC-subtype. Ultimately, the MSCs contribution to tumor progression could provide targets with potential for eradicating resistant metastatic disease.

Flavonoids Restore Platinum Drug Sensitivity to Ovarian Carcinoma Cells in a Phospho-ERK1/2-Dependent Fashion

Ovarian cancer (OC) is the second most common type of gynecological malignancy; it has poor survival rates and is frequently (>75%) diagnosed at an advanced stage. Platinum-based chemotherapy, with, e.g., carboplatin, is the standard of care for OC, but toxicity and acquired resistance to therapy have proven challenging. Despite advances in OC diagnosis and treatment, approximately 85% of patients will experience relapse, mainly due to chemoresistance. The latter is attributed to alterations in the cancer cells and is also mediated by tumor microenvironment (TME). Recently, we reported the synthesis of a platinum (IV) prodrug that exhibits equal potency toward platinum-sensitive and resistant OC cell lines. Here, we investigated the effect of TME on platinum sensitivity. Co-culture of OC cells with murine or human mesenchymal stem cells (MS-5 and HS-5, respectively) rendered them resistant to chemotherapeutic agents, including platinum, paclitaxel and colchicine. Platinum resistance was also conferred by co-culture with differentiated murine adipocyte progenitor cells. Exposure of OC cells to chemotherapeutic agents resulted in activation of phospho-ERK1/2. Co-culture with MS-5, which conferred drug resistance, was accompanied by blockage of phospho-ERK1/2 activation. The flavonoids fisetin and quercetin were active in restoring ERK phosphorylation, as well as sensitivity to platinum compounds. Exposure of OC cells to cobimetinib-a MEK1 inhibitor that also inhibits extracellular signal-regulated kinase (ERK) phosphorylation-which resulted in reduced sensitivity to the platinum compound. This suggests that ERK activity is involved in mediating the function of flavonoids in restoring platinum sensitivity to OC co-cultured with cellular components of the TME. Our data show the potential of combining flavonoids with standard therapy to restore drug sensitivity to OC cells and overcome TME-mediated platinum drug resistance.

Targeting the Tumor Microenvironment in Neuroblastoma: Recent Advances and Future Directions

Neuroblastoma (NB) is the most common pediatric tumor malignancy that originates from the neural crest and accounts for more than 15% of all the childhood deaths from cancer. The neuroblastoma cancer research has long been focused on the role of MYCN oncogene amplification and the contribution of other genetic alterations in the progression of this malignancy. However, it is now widely accepted that, not only tumor cells, but the components of tumor microenvironment (TME), including extracellular matrix, stromal cells and immune cells, also contribute to tumor progression in neuroblastoma. The complexity of different components of tumor stroma and their resemblance with surrounding normal tissues pose huge challenges for therapies targeting tumor microenvironment in NB. Hence, the detailed understanding of the composition of the TME of NB is crucial to improve existing and future potential immunotherapeutic approaches against this childhood cancer. In this review article, I will discuss different components of the TME of NB and the recent advances in the strategies, which are used to target the tumor microenvironment in neuroblastoma.

Preclinical models for neuroblastoma: Advances and challenges

Neuroblastoma is a paediatric cancer of the sympathetic nervous system and the most common solid tumour of infancy, contributing to 15% of paediatric oncology deaths. Current therapies are not effective in the long-term treatment of almost 80% of patients with this clinically aggressive disease. The primary challenge in the identification and validation of new agents for paediatric drug development is the accurate representation of tumour biology and diversity. In addition to this limitation, the low incidence of neuroblastoma makes the recruitment of eligible patients for early phase clinical trials highly challenging and highlights the need for robust preclinical testing to ensure that the best treatments are selected. The research field requires new preclinical models, technologies, and concepts to tackle these problems. Tissue engineering offers attractive tools to assist in the development of three-dimensional (3D) cell models using various biomaterials and manufacturing approaches that recreate the geometry, mechanics, heterogeneity, metabolic gradients, and cell communication of the native tumour microenvironment. In this review, we discuss current experimental models and assess their abilities to reflect the structural organisation and physiological conditions of the human body, in addition to current and new techniques to recapitulate the tumour niche using tissue-engineered platforms. Finally, we will discuss the possible use of novel 3D in vitro culture systems to address open questions in neuroblastoma biology.

Induction of MEK/ERK activity by AZD8055 confers acquired resistance in neuroblastoma

Mammalian target of rapamycin (mTOR) complex (mTORC) is frequently activated in diverse cancers. Although dual mTORC1/2 inhibitors are currently under development to treat various malignancies, the emergence of drug resistance has proven to be a major complication. AZD8055 is a novel, potent ATP-competitive and specific inhibitor of mTOR kinase activity, which blocks both mTORC1 and mTORC2 activation. In this study, we acquired AZD8055-resistant neuroblastoma (NB) cell sublines by using prolonged stepwise escalation of AZD8055 exposure (4-12 weeks). Here we demonstrate that the AZD8055-resistant sublines (TGW-R and SMS-KAN-R) exhibited marked resistance to AZD8055 compared to the parent cells (TGW and SMS-KAN). The cell cycle G1/S transition was advanced in resistant cells. In addition, the resistance against AZD8055 correlated with over-activation of MEK/ERK signaling pathway. Furthermore, combination of AZD8055 and MEK inhibitor U0126 enhanced the growth inhibition of resistant cells significantly in vitro and in vivo. In conclusion, these data show that targeting mTOR kinase and MEK/ERK signaling simultaneously might help to overcome AZD8055 resistance in NB.

Anti-tumor effect of AZD8055 against neuroblastoma cells in vitro and in vivo

Neuroblastoma (NB) is one of the most common solid tumors in children. High-risk NB remains lethal in about 50% of patients despite comprehensive and intensive treatments. Activation of PI3K/Akt/mTOR signaling pathway correlates with oncogenesis, poor prognosis and chemotherapy resistance in NB. Due to its central role in growth and metabolism, mTOR seems to be an important factor in NB, making it a possible target for NB. In this study, we investigated the effect of AZD8055, a potent dual mTORC1-mTORC2 inhibitor, in NB cell lines. Our data showed that mTOR signaling was extensively activated in NB cells. The activity of mTOR and downstream molecules were down-regulated in AZD8055-treated NB cells. Significantly, AZD8055 effectively inhibited cell growth and induced cell cycle arrest, autophagy and apoptosis in NB cells. Moreover, AZD8055 significantly reduced tumor growth in mice xenograft model without apparent toxicity. Taken together, our results highlight the potential of mTOR as a promising target for NB treatment. Therefore, AZD8055 may be further investigated for treatment in clinical trials for high risk NB.

Let-7a inhibits migration of melanoma cells via down-regulation of HMGA2 expression

This study aimed to investigate the effects of exosomes derived from BM-MSCs transduced with let-7a on B16f10 cells and BM-MSCs. BM-MSCs were transduced with let-7a and the exosomes of them were isolated for further culture of B16f10 cells and BM-MSCs. The migration of B16f10 cells were detected by transwell, proliferation of B16f10 cells and BM-MSCs was examined by MTT method, HMGA2 expression was measured by western blot. In addition, the let-7a secreted level in exosomes and IGF level were measured by RT-PCR and ELISA respectively. Our results showed that the level of let-7a in exosomes derived from Let-7a-transducted BM-MSCs was increased after treated by exosomes. HMGA2 in B16f10 cells was down-regulated and cell survival rate of BM-MSCs was decreased. However, neither cell survival rate of B16f10 cells nor IGF-1 secreted by B16f10 cells in different groups had significant differences. In conclusion, Let-7a contained in exosomes can inhibit the migration of Melanoma cells and inhibit the proliferation of BM-MSCs.

Specially modified stromal and immune microenvironment in injected bone marrow following intrabone transplantation facilitates allogeneic hematopoietic stem cell engraftment

For allogeneic hematopoietic stem cell transplantation (HSCT), the first key step is the engraftment of hematopoietic stem cells (HSCs) across the major histocompatibility complex (MHC) barrier. Intrabone bone marrow transplantation (IBBMT) could replace more recipient stromal cells with donor cells and facilitate allogeneic organ transplantation compared with the conventional intravenous approach. However, it remains unknown whether and how IBBMT reconstructs the immune microenvironment for allogeneic HSCs. We explored where the BM microenvironment changes by determining BM stromal cell chimerism and measuring the change in CXCL-12 expression and regulatory T cells in recipient BM. We found that most stromal cells were replaced by allogeneic cells in the injected BM, with higher expression of immune regulatory cytokines (interleukin-10) compared with the contralateral BM and the intravenous group BM. This difference was independent of injury caused by intrabone injection. Consistent with the microenvironment modification, the allogeneic the engraftment rate and reconstitution capacity of HSCs were enhanced in the injected BM compared with the contralateral BM and intravenous group BM. Surgical removal of the injected bone at 7 days rather than 21 days reduced the levels of allogeneic granulocytes and HSCs in the peripheral blood. In conclusion, IBBMT specially modifies stromal cells in the injected BM which provide immune protective cues that improve the engraftment of allogeneic HSCs in an early period.

Mesenchymal stem cells secretomes' affect multiple myeloma translation initiation

Bone marrow mesenchymal stem cells' (BM-MSCs) role in multiple myeloma (MM) pathogenesis is recognized. Recently, we have published that co-culture of MM cell lines with BM-MSCs results in mutual modulation of phenotype and proteome (via translation initiation (TI) factors eIF4E/eIF4GI) and that there are differences between normal donor BM-MSCs (ND-MSCs) and MM BM-MSCs (MM-MSCs) in this crosstalk. Here, we aimed to assess the involvement of soluble BM-MSCs' (ND, MM) components, more easily targeted, in manipulation of MM cell lines phenotype and TI with specific focus on microvesicles (MVs) capable of transferring critical biological material. We applied ND and MM-MSCs 72h secretomes to MM cell lines (U266 and ARP-1) for 12-72h and then assayed the cells' (viability, cell count, cell death, proliferation, cell cycle, autophagy) and TI (factors: eIF4E, teIF4GI; regulators: mTOR, MNK1/2, 4EBP; targets: cyclin D1, NFκB, SMAD5, cMyc, HIF1α). Furthermore, we dissected the secretome into >100kDa and <100kDa fractions and repeated the experiments. Finally, MVs were isolated from the ND and MM-MSCs secretomes and applied to MM cell lines. Phenotype and TI were assessed. Secretomes of BM-MSCs (ND, MM) significantly stimulated MM cell lines' TI, autophagy and proliferation. The dissected secretome yielded different effects on MM cell lines phenotype and TI according to fraction (>100kDa- repressed; <100kDa- stimulated) but with no association to source (ND, MM). Finally, in analyses of MVs extracted from BM-MSCs (ND, MM) we witnessed differences in accordance with source: ND-MSCs MVs inhibited proliferation, autophagy and TI whereas MM-MSCs MVs stimulated them. These observations highlight the very complex communication between MM and BM-MSCs and underscore its significance to major processes in the malignant cells. Studies into the influential MVs cargo are underway and expected to uncover targetable signals in the regulation of the TI/proliferation/autophagy cascade.

Microencapsulation of Neuroblastoma Cells and Mesenchymal Stromal Cells in Collagen Microspheres: A 3D Model for Cancer Cell Niche Study

There is a growing trend for researchers to use in vitro 3D models in cancer studies, as they can better recapitulate the complex in vivo situation. And the fact that the progression and development of tumor are closely associated to its stromal microenvironment has been increasingly recognized. The establishment of such tumor supportive niche is vital in understanding tumor progress and metastasis. The mesenchymal origin of many cells residing in the cancer niche provides the rationale to include MSCs in mimicking the niche in neuroblastoma. Here we co-encapsulate and co-culture NBCs and MSCs in a 3D in vitro model and investigate the morphology, growth kinetics and matrix remodeling in the reconstituted stromal environment. Results showed that the incorporation of MSCs in the model lead to accelerated growth of cancer cells as well as recapitulation of at least partially the tumor microenvironment in vivo. The current study therefore demonstrates the feasibility for the collagen microsphere to act as a 3D in vitro cancer model for various topics in cancer studies.