Establishment and molecular characterisation of seven novel soft-tissue sarcoma cell lines

Preclinical models of soft tissue sarcomas - generation and applications to enhance translational research

Soft tissue sarcomas (STS) represent a large group of rare and ultra-rare tumors distinguished by unique morphological, molecular and clinical features. Patients with such rare cancers are generally underrepresented in clinical trials which has limited the introduction of new treatment options and subsequent improvement of patient outcomes. Preclinical models of STS that recapitulate the human disease can aid progress in identifying new effective treatments. However, due to the rarity of these tumors there are limited STS models available. Here we review the existing preclinical models of STS, including patient-derived cell lines and organoids, patient-derived xenografts and genetically engineered mouse models. We discuss the advantages and disadvantages of the different models and describe to what extent they have aided clinical translation. Finally, we consider what can be done in the future to enhance their predictivity in the preclinical setting.

Establishment and characterization of the novel myxofibrosarcoma cell line, SMU-MFS

Myxofibrosarcoma (MFS) is one of the most common soft-tissue sarcomas in elderly patients. Owing to the limited efficacy of chemotherapy and radiotherapy, complete resection is the only available curative treatment. Therefore, developing novel therapies for MFS is important to improve clinical outcomes. Herein, a novel MFS cell line, namely SMU-MFS, was established to better understand the biologic characteristics of MFS and develop new therapies. A tissue sample from the surgically resected tumor tissue of a 56-year-old patient with a tumor was subjected to primary culture. The cell line was established and authenticated by assessing the short tandem repeats of DNA microsatellites. The monolayer cultures of SMU-MFS cells exhibited constant growth, spheroid formation, and invasive capacity. Furthermore, the cells exhibited low chemosensitivity to doxorubicin, eribulin, and pazopanib, which are used to inhibit metastatic progression. In addition, of the four mice inoculated with SMU-MFS cells, tumors developed in two mice after 8 weeks. Altogether, the findings of this study suggest that the SMU-MFS cell line can be a useful tool for investigating MFS development and evaluating novel therapeutic agents.

Genetic Screen in a Preclinical Model of Sarcoma Development Defines Drivers and Therapeutic Vulnerabilities

PURPOSE

High-grade complex karyotype sarcomas are a heterogeneous group of tumors with a uniformly poor prognosis. Within complex karyotype sarcomas, there are innumerable genetic changes but identifying those that are clinically relevant has been challenging.

EXPERIMENTAL DESIGN

To address this, we utilized a pooled genetic screening approach, informed by The Cancer Genome Atlas (TCGA) data, to identify key drivers and modifiers of sarcoma development that were validated in vivo.

RESULTS

YAP1 and wild-type KRAS were validated as drivers and transformed human mesenchymal stem cells into two distinct sarcoma subtypes, undifferentiated pleomorphic sarcoma and myxofibrosarcoma, respectively. A subset of tumors driven by CDK4 and PIK3CA reflected leiomyosarcoma and osteosarcoma demonstrating the plasticity of this approach and the potential to investigate sarcoma subtype heterogeneity. All generated tumors histologically reflected human sarcomas and had increased aneuploidy as compared to simple karyotype sarcomas. Comparing differential gene expression of TCGA samples to model data identified increased oxidative phosphorylation signaling in YAP1 tumors. Treatment of a panel of soft tissue sarcomas with a combination of YAP1 and oxidative phosphorylation inhibitors led to significantly decreased viability.

CONCLUSIONS

Transcriptional co-analysis of TCGA patient samples to YAP1 and KRAS model tumors supports that these sarcoma subtypes lie along a spectrum of disease and adds guidance for further transcriptome-based refinement of sarcoma subtyping. This approach can be used to begin to understand pathways and mechanisms driving human sarcoma development, the relationship between sarcoma subtypes, and to identify and validate new therapeutic vulnerabilities for this aggressive and heterogeneous disease.

Establishment and characterization of 18 Sarcoma Cell Lines: Unraveling the Molecular Mechanisms of Doxorubicin Resistance in Sarcoma Cell Lines

Sarcomas, malignant tumors from mesenchymal tissues, exhibit poor prognosis despite advancements in treatment modalities such as surgery, radiotherapy, and chemotherapy, with doxorubicin being a cornerstone treatment. Resistance to doxorubicin remains a significant hurdle in therapy optimization. This study aims to dissect the molecular bases of doxorubicin resistance in sarcoma cell lines, which could guide the development of tailored therapeutic strategies. Eighteen sarcoma cell lines from 14 patients were established under ethical approvals and classified into seven subtypes. Molecular, genomic, and transcriptomic analyses included whole-exome sequencing, RNA sequencing, drug sensitivity assays, and pathway enrichment studies to elucidate the resistance mechanisms. Variability in doxorubicin sensitivity was linked to specific genetic alterations, including mutations in TP53 and variations in the copy number of genomic loci like 11q24.2. Transcriptomic profiling divided cell lines into clusters by karyotype complexity, influencing drug responses. Additionally, pathway analyses highlighted the role of signaling pathways like WNT/BETA-CATENIN and HEDGEHOG in doxorubicin-resistant lines. Comprehensive molecular profiling of sarcoma cell lines has revealed complex interplays of genetic and transcriptomic factors dictating doxorubicin resistance, underscoring the need for personalized medicine approaches in sarcoma treatment. Further investigations into these resistance mechanisms could facilitate the development of more effective, customized therapy regimens.

A clinically compatible in vitro drug-screening platform identifies therapeutic vulnerabilities in primary cultures of brain metastases

PURPOSE

Brain metastases represent the most common intracranial tumors in adults and are associated with a poor prognosis. We used a personalized in vitro drug screening approach to characterize individual therapeutic vulnerabilities in brain metastases.

METHODS

Short-term cultures of cancer cells isolated from brain metastasis patients were molecularly characterized using next-generation sequencing and functionally evaluated using high-throughput in vitro drug screening to characterize pharmacological treatment sensitivities.

RESULTS

Next-generation sequencing identified matched genetic alterations in brain metastasis tissue samples and corresponding short-term cultures, suggesting that short-term cultures of brain metastases are suitable models for recapitulating the genetic profile of brain metastases that may determine their sensitivity to anti-cancer drugs. Employing a high-throughput in vitro drug screening platform, we successfully screened the cultures of five brain metastases for response to 267 anticancer compounds and related drug response to genetic data. Among others, we found that targeted treatment with JAK3, HER2, or FGFR3 inhibitors showed anti-cancer effects in individual brain metastasis cultures.

CONCLUSION

Our preclinical study provides a proof-of-concept for combining molecular profiling with in vitro drug screening for predictive evaluation of therapeutic vulnerabilities in brain metastasis patients. This approach could advance the use of patient-derived cancer cells in clinical practice and might eventually facilitate decision-making for personalized drug treatment.

Clinical Implications and Molecular Features of Extracellular Matrix Networks in Soft Tissue Sarcomas

PURPOSE

The landscape of extracellular matrix (ECM) alterations in soft tissue sarcomas (STS) remains poorly characterized. We aimed to investigate the tumor ECM and adhesion signaling networks present in STS and their clinical implications.

EXPERIMENTAL DESIGN

Proteomic and clinical data from 321 patients across 11 histological subtypes were analyzed to define ECM and integrin adhesion networks. Subgroup analysis was performed in leiomyosarcomas (LMS), dedifferentiated liposarcomas (DDLPS), and undifferentiated pleomorphic sarcomas (UPS).

RESULTS

This analysis defined subtype-specific ECM profiles including enrichment of basement membrane proteins in LMS and ECM proteases in UPS. Across the cohort, we identified three distinct coregulated ECM networks which are associated with tumor malignancy grade and histological subtype. Comparative analysis of LMS cell line and patient proteomic data identified the lymphocyte cytosolic protein 1 cytoskeletal protein as a prognostic factor in LMS. Characterization of ECM network events in DDLPS revealed three subtypes with distinct oncogenic signaling pathways and survival outcomes. Evaluation of the DDLPS subtype with the poorest prognosis nominates ECM remodeling proteins as candidate antistromal therapeutic targets. Finally, we define a proteoglycan signature that is an independent prognostic factor for overall survival in DDLPS and UPS.

CONCLUSIONS

STS comprise heterogeneous ECM signaling networks and matrix-specific features that have utility for risk stratification and therapy selection, which could in future guide precision medicine in these rare cancers.

A novel patient-derived immortalised cell line of myxofibrosarcoma: a tool for preclinical drugs testing and the generation of near-patient models

BACKGROUND

Myxofibrosarcoma is a rare malignant soft tissue sarcoma characterised by multiple local recurrence and can become of higher grade with each recurrence. Consequently, myxofibrosarcoma represents a burden for patients, a challenge for clinicians, and an interesting disease to study tumour progression. Currently, few myxofibrosarcoma preclinical models are available.

METHODS

In this paper, we present a spontaneously immortalised myxofibrosarcoma patient-derived cell line (MF-R 3). We performed phenotypic characterization through multiple biological assays and analyses: proliferation, clonogenic potential, anchorage-independent growth and colony formation, migration, invasion, AgNOR staining, and ultrastructural evaluation.

RESULTS

MF-R 3 cells match morphologic and phenotypic characteristics of the original tumour as 2D cultures, 3D aggregates, and on the chorioallantoic membrane of chick embryos. Overall results show a clear neoplastic potential of this cell line. Finally, we tested MF-R 3 sensitivity to anthracyclines in 2D and 3D conditions finding a good response to these drugs.

CONCLUSIONS

In conclusion, we established a novel patient-derived myxofibrosarcoma cell line that, together with the few others available, could serve as an important model for studying the molecular pathogenesis of myxofibrosarcoma and for testing new drugs and therapeutic strategies in diverse experimental settings.

Preclinical Models of Visceral Sarcomas

Visceral sarcomas are a rare malignant subgroup of soft tissue sarcomas (STSs). STSs, accounting for 1% of all adult tumors, are derived from mesenchymal tissues and exhibit a wide heterogeneity. Their rarity and the high number of histotypes hinder the understanding of tumor development mechanisms and negatively influence clinical outcomes and treatment approaches. Although some STSs (~20%) have identifiable genetic markers, as specific mutations or translocations, most are characterized by complex genomic profiles. Thus, identification of new therapeutic targets and development of personalized therapies are urgent clinical needs. Although cell lines are useful for preclinical investigations, more reliable preclinical models are required to develop and test new potential therapies. Here, we provide an overview of the available in vitro and in vivo models of visceral sarcomas, whose gene signatures are still not well characterized, to highlight current challenges and provide insights for future studies.

Novel PD-L1- and collagen-expressing patient-derived cell line of undifferentiated pleomorphic sarcoma (JBT19) as a model for cancer immunotherapy

Soft tissue sarcomas are aggressive mesenchymal-origin malignancies. Undifferentiated pleomorphic sarcoma (UPS) belongs to the aggressive, high-grade, and least characterized sarcoma subtype, affecting multiple tissues and metastasizing to many organs. The treatment of localized UPS includes surgery in combination with radiation therapy. Metastatic forms are treated with chemotherapy. Immunotherapy is a promising treatment modality for many cancers. However, the development of immunotherapy for UPS is limited due to its heterogeneity, antigenic landscape variation, lower infiltration with immune cells, and a limited number of established patient-derived UPS cell lines for preclinical research. In this study, we established and characterized a novel patient-derived UPS cell line, JBT19. The JBT19 cells express PD-L1 and collagen, a ligand of the immune checkpoint molecule LAIR-1. JBT19 cells can form spheroids in vitro and solid tumors in immunodeficient nude mice. We found JBT19 cells induce expansion of JBT19-reactive autologous and allogeneic NK, T, and NKT-like cells, and the reactivity of the expanded cells was associated with cytotoxic impact on JBT19 cells. The PD-1 and LAIR-1 ligand-expressing JBT19 cells show ex vivo immunogenicity and effective in vivo xenoengraftment properties that can offer a unique resource in the preclinical research developing novel immunotherapeutic interventions in the treatment of UPS.

Modeling Myxofibrosarcoma: Where Do We Stand and What Is Missing?

Myxofibrosarcoma (MFS) is a malignant soft tissue sarcoma (STS) that originates in the body's connective tissues. It is characterized by the presence of myxoid (gel-like) and fibrous components and typically affects patients after the fifth decade of life. Considering the ongoing trend of increasing lifespans across many nations, MFS is likely to become the most common musculoskeletal sarcoma in the future. Although MFS patients have a lower risk of developing distant metastases compared with other STS cases, MFS is characterized by a high frequency of local recurrence. Notably, in 40-60% of the patients where the tumor recurs, it does so multiple times. Consequently, patients may undergo multiple local surgeries, removing the risk of potential amputation. Furthermore, because the tumor relapses generally have a higher grade, they exhibit a decreased response to radio and chemotherapy and an increased tendency to form metastases. Thus, a better understanding of MFS is required, and improved therapeutic options must be developed. Historically, preclinical models for other types of tumors have been instrumental in obtaining a better understanding of tumor development and in testing new therapeutic approaches. However, few MFS models are currently available. In this review, we will describe the MFS models available and will provide insights into the advantages and constraints of each model.

Animal models of Soft Tissue Sarcoma for alternative anticancer therapy studies: characterization of the A-72 Canine Cell Line

Canine Soft Tissue Sarcoma (STS) cell line A-72 has been largely employed for antiviral and antiproliferative studies. However, there are few information on their characteristics. Our aim was to evaluate A-72 expression level of genes and proteins involved in the innate immune response and cell cycle, their ability to respond to infective stressors and their possible use as a cellular model for anti-cancer studies in human and animal medicine. For this purpose, we evaluated the basal expression of immune-related, cell cycle and DNA repair genes on this cell line and tumoral tissues. A-72 ability to respond to a wild-type strain of Salmonella typhimurium was assessed. S. typhimurium showed ability to penetrate A-72 causing pro-inflammatory response accompanied by a decrease of cell viability. IL10 and IL18 genes were not expressed in A-72 while CXCL8, NOS2, CXCR4 and PTEN were highly expressed in all samples and TP53 was slightly expressed, as shown in human STS. Our results outline the ability of A-72 to respond to a bacterial agent by modifying the expression of important genes involved in innate immune response and provide a useful model for in vitro evaluation of new therapeutic approaches that could be translated into the human oncology.

New established cell lines from undifferentiated pleomorphic sarcoma for in vivo study

As a high-grade soft-tissue sarcoma (STS), undifferentiated pleomorphic sarcoma (UPS) is highly recurrent and malignant. UPS is categorized as a tumor of uncertain differentiation and has few options for treatment due to its lack of targetable genetic alterations. There are also few cell lines that provide a representative model for UPS, leading to a dearth of experimental research. Here, we established and characterized new cell lines derived from two recurrent UPS tissues. Cells were obtained from UPS tissues by mincing, followed by extraction or dissociation using enzymes and culture in a standard culture environment. Cells were maintained for several months without artificial treatment, and some cell clones were found to be tumorigenic in an immunodeficient mouse model. Interestingly, some cells formed tumors in vivo when injected after aggregation in a non-adherent culture system for 24 h. The tissues from in vivo study and tissues from patients shared common histological characteristics. Pathways related to the cell cycle, such as DNA replication, were enriched in both cell clones. Pathways related to cell-cell adhesion and cell-cell signaling were also enriched, suggesting a role of the mesenchymal-to-epithelial transition for tumorigenicity in vivo. These new UPS cell lines may facilitate research to identify therapeutic strategies for UPS. [BMB Reports 2023; 56(4): 258-264].

Comparison of biological behavior of lacrimal gland adenoid cystic carcinoma with high-grade transformation cells

AIM

To evaluate the differences between human lacrimal gland adenoid cystic carcinoma with high-grade transformation (LACC-HGT) primary cells cultured by high-grade transformation tissue and non-high-grade transformation (non-HGT) primary cells cultured by non-high-grade transformation tissue in proliferation, metastasis, drug susceptibility, and genes.

METHODS

LACC-HGT primary cells were established by tissue block culture, and the 4^th to 10^th generation primary cells were selected as research objects. The cells were preliminarily identified by immunofluorescent staining. The differences between non-HGT and LACC-HGT primary cells in terms of proliferation, metastasis, and drug susceptibility were compared by cell counting kit-8 (CCK-8) assay, wound healing, and drug sensitivity experiments. Differentially expressed genes were screened using mRNA array. Gene expression was analyzed using real-time quantitative polymerase chain reaction (RT-qPCR).

RESULTS

LACC-HGT primary cells were successfully cultured by tissue block culture. Immunofluorescence staining results showed that cytokeratin (CK) and CK7 expression levels were positive in LACC-HGT primary cells. CCK-8 results showed that the proliferation ability of LACC-HGT cells was significantly higher than that of non-HGT cells. Wound healing experiment showed that the migration ability of LACC-HGT cells was significantly higher than that of non-HGT cells. LACC-HGT cells were also less sensitive to cisplatin and paclitaxel than non-HGT cells. Compared with non-HGT cells, 9566 differentially expressed genes were found in LACC-HGT primary cells, of which 5162 were up-regulated and 4404 were down-regulated. The expression of N-acetylneuraminate pyruvate lyase (NPL), MARVEL domain containing 3 (MARVELD3), syntabulin (SYBU), and allograft inflammatory factor 1 (AIF1) was higher in LACC-HGT cells than in non-HGT cells, whereas that of periostin (POSTN) was lower.

CONCLUSION

LACC-HGT primary cells have faster proliferation, stronger migration ability, and poorer sensitivity to chemotherapy drugs than non-HGT primary cells. The expression of mRNAs in non-HGT and LACC-HGT primary cells are significantly different. These features are speculated to be the reasons why high-grade transformation tissues exhibit higher malignant degree and poorer prognosis than their counterparts.

Experimental models of undifferentiated pleomorphic sarcoma and malignant peripheral nerve sheath tumor

Undifferentiated pleomorphic sarcoma (UPS) and malignant peripheral nerve sheath tumor (MPNST) are aggressive soft tissue sarcomas that do not respond well to current treatment modalities. The limited availability of UPS and MPNST cell lines makes it challenging to identify potential therapeutic targets in a laboratory setting. Understanding the urgent need for improved treatments for these tumors and the limited cellular models available, we generated additional cell lines to study these rare cancers. Patient-derived tumors were used to establish 4 new UPS models, including one radiation-associated UPS-UPS271.1, UPS511, UPS0103, and RIS620, one unclassified spindle cell sarcoma-USC060.1, and 3 new models of MPNST-MPNST007, MPNST3813E, and MPNST4970. This study examined the utility of the new cell lines as sarcoma models by assessing their tumorigenic potential and mutation status for known sarcoma-related genes. All the cell lines formed colonies and migrated in vitro. The in vivo tumorigenic potential of the cell lines and corresponding xenografts was determined by subcutaneous injection or xenograft re-passaging into immunocompromised mice. USC060.1 and UPS511 cells formed tumors in mice upon subcutaneous injection. UPS0103 and RIS620 tumor implants formed tumors in vivo, as did MPNST007 and MPNST3813E tumor implants. Targeted sequencing analysis of a panel of genes frequently mutated in sarcomas identified TP53, RB1, and ATRX mutations in a subset of the cell lines. These new cellular models provide the scientific community with powerful tools for detailed studies of tumorigenesis and for investigating novel therapies for UPS and MPNST.

Experimental Models for SARS-CoV-2 Infection

Severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2) is a novel virus that causes coronavirus disease 2019 (COVID-19). To understand the identity, functional characteristics and therapeutic targets of the virus and the diseases, appropriate infection models that recapitulate the in vivo pathophysiology of the viral infection are necessary. This article reviews the various infection models, including Vero cells, human cell lines, organoids, and animal models, and discusses their advantages and disadvantages. This knowledge will be helpful for establishing an efficient system for defense against emerging infectious diseases.

The important role of routine cytopathology in pediatric precision oncology

BACKGROUND

The development of high-throughput drug screening (HTS) using primary cultures provides a promising, clinically translatable approach to tailoring treatment strategies for patients with cancer. However, this has been challenging for solid tumors because of often limited amounts of tissue available. In most cases, in vitro expansion is required before HTS, which may lead to overgrowth and contamination by non-neoplastic cells.

METHODS

In this study, hematoxylin and eosin staining and immunohistochemical staining were performed on 129 cytopathology cases from 95 patients. These cytopathology cases comprised cell block preparations derived from primary tumor specimens or patient-derived xenografts as part of a pediatric precision oncology trial. Cytopathology cases were compared with the morphology and immunohistochemical staining profile of the original tumor. Cases were reported as tumor cells present, equivocal, or tumor cells absent. The HTS results from cytopathologically validated cultures were incorporated into a multidisciplinary tumor board report issued to the treating clinician to guide clinical decision making.

RESULTS

On cytopathologic examination, tumor cells were present in 77 of 129 cases (60%) and were absent in 38 of 129 cases (29%), whereas 14 of 129 cases (11%) were equivocal. Cultures that contained tumor cells resembled the tumors from which they were derived.

CONCLUSIONS

Cytopathologic examination of tumor cell block preparations is feasible and provides detailed morphologic characterization. Cytopathologic examination is essential for ensuring that samples submitted for HTS contain representative tumor cells and that in vitro drug sensitivity data are clinically translatable.

PDX-Derived Ewing's Sarcoma Cells Retain High Viability and Disease Phenotype in Alginate Encapsulated Spheroid Cultures

Simple Summary

Ewing’s Sarcoma (ES) is the second most frequent bone tumour in children and young adults, with very aggressive behaviour and significant disease recurrence. To better study the disease and find new therapies, experimental models are needed. Recently, patient-derived xenografts (PDX), obtained by implanting patient tumour samples in immunodeficient mice, have been developed. However, when ES cells are extracted from the patient’s tumour or from PDX and placed on plasticware surfaces, they lose their original 3D configuration, cell identity and function. To overcome these issues, we implemented cultures of PDX-derived ES cells, by making them aggregate to form ES cell spheroids and then encapsulating these 3D spheroids into a hydrogel, alginate, to stabilize the culture. We show that this methodology maintained ES cell viability and intrinsic characteristics of the original ES tumour cells for at least one month and that it is suitable for study the effect of anticancer drugs.

Abstract

Ewing’s Sarcoma (ES) is the second most frequent malignant bone tumour in children and young adults and currently only untargeted chemotherapeutic approaches and surgery are available as treatment, although clinical trials are on-going for recently developed ES-targeted therapies. To study ES pathobiology and develop novel drugs, established cell lines and patient-derived xenografts (PDX) are the most employed experimental models. Nevertheless, the establishment of ES cell lines is difficult and the extensive use of PDX raises economic/ethical concerns. There is a growing consensus regarding the use of 3D cell culture to recapitulate physiological and pathophysiological features of human tissues, including drug sensitivity. Herein, we implemented a 3D cell culture methodology based on encapsulation of PDX-derived ES cell spheroids in alginate and maintenance in agitation-based culture systems. Under these conditions, ES cells displayed high proliferative and metabolic activity, while retaining the typical EWSR1-FLI1 chromosomal translocation. Importantly, 3D cultures presented reduced mouse PDX cell contamination compared to 2D cultures. Finally, we show that these 3D cultures can be employed in drug sensitivity assays, with results similar to those reported for the PDX of origin. In conclusion, this novel 3D cell culture method involving ES-PDX-derived cells is a suitable model to study ES pathobiology and can assist in the development of novel drugs against this disease, complementing PDX studies.

MNK1 and MNK2 enforce expression of E2F1, FOXM1, and WEE1 to drive soft tissue sarcoma

Soft tissue sarcoma (STS) is a heterogeneous disease that arises from connective tissues. Clinical outcome of patients with advanced tumors especially de-differentiated liposarcoma and uterine leiomyosarcoma remains unsatisfactory, despite intensive treatment regimens including maximal surgical resection, radiation, and chemotherapy. MAP kinase-interacting serine/threonine-protein kinase 1 and 2 (MNK1/2) have been shown to contribute to oncogenic translation via phosphorylation of eukaryotic translation initiation factor 4E (eIF4E). However, little is known about the role of MNK1/2 and their downstream targets in STS. In this study, we show that depletion of either MNK1 or MNK2 suppresses cell viability, anchorage-independent growth, and tumorigenicity of STS cells. We also identify a compelling antiproliferative efficacy of a novel, selective MNK inhibitor ETC-168. Cellular responsiveness of STS cells to ETC-168 correlates positively with that of phosphorylated ribosomal protein S6 (RPS6). Mirroring MNK1/2 silencing, ETC-168 treatment strongly blocks eIF4E phosphorylation and represses expression of sarcoma-driving onco-proteins including E2F1, FOXM1, and WEE1. Moreover, combination of ETC-168 and MCL1 inhibitor S63845 exerts a synergistic antiproliferative activity against STS cells. In summary, our study reveals crucial roles of MNK1/2 and their downstream targets in STS tumorigenesis. Our data encourage further clinical translation of MNK inhibitors for STS treatment.

Sarcoma treatment in the era of molecular medicine

Sarcomas are heterogeneous and clinically challenging soft tissue and bone cancers. Although constituting only 1% of all human malignancies, sarcomas represent the second most common type of solid tumors in children and adolescents and comprise an important group of secondary malignancies. More than 100 histological subtypes have been characterized to date, and many more are being discovered due to molecular profiling. Owing to their mostly aggressive biological behavior, relative rarity, and occurrence at virtually every anatomical site, many sarcoma subtypes are in particular difficult-to-treat categories. Current multimodal treatment concepts combine surgery, polychemotherapy (with/without local hyperthermia), irradiation, immunotherapy, and/or targeted therapeutics. Recent scientific advancements have enabled a more precise molecular characterization of sarcoma subtypes and revealed novel therapeutic targets and prognostic/predictive biomarkers. This review aims at providing a comprehensive overview of the latest advances in the molecular biology of sarcomas and their effects on clinical oncology; it is meant for a broad readership ranging from novices to experts in the field of sarcoma.

Establishment and characterization of NCC-MFS2-C1: a novel patient-derived cancer cell line of myxofibrosarcoma

Myxofibrosarcoma (MFS) is among the most aggressive and complex sarcoma types that require novel therapeutic approaches for improved clinical outcomes. MFS displays highly complex karyotypes, and frequent alterations in p53 signaling and cell cycle checkpoint genes as well as loss-of-function mutations in NF1 and PTEN have been reported. The effects of radiotherapy and chemotherapy on MFS are limited, and complete surgical resection is the only curative treatment. Thus, the development of novel therapeutic strategies for MFS has long been long desired for MFS. Patient-derived cell lines are an essential tool for basic and translational research in oncology. However, public cell banks provide only a limited number of MFS cell lines. In this study, we aimed to develop a novel patient-derived MFS cell line, which was established from the primary tumor tissue of a 71-year-old male patient with MFS and was named NCC-MFS2-C1. A single-nucleotide polymorphism assay revealed that NCC-MFS2-C1 cells exhibited gain and loss of genetic loci. NCC-MFS2-C1 cells were maintained as a monolayer culture for over 24 passages for 10 months. The cells exhibited spindle-like morphology, continuous growth, and capacity for spheroid formation and invasion. Screening of 213 anticancer agents revealed that bortezomib, gemcitabine, romidepsin, and topotecan at low concentrations inhibited the proliferation of NCC-MFS2-C1 cells. In conclusion, we established a novel MFS cell line, NCC-MFS2-C1, which can be used for studying the molecular mechanisms underlying tumor development and for the in vitro screening of anti-cancer drugs.

Mandibular undifferentiated pleomorphic sarcoma: Molecular analysis of a primary cell population

Background

Undifferentiated pleomorphic sarcomas are one of the most common subtypes of soft tissue sarcomas. These are aggressive mesenchymal tumors and are devoid of the major known biomarkers except vimentin. Our objective was to establish and characterize a primary cell population from a mandibular UPS specimen.

Methods

The tumor was surgically removed from the right mandible of a 24‐year‐old male with IRB approved signed consent. Tumor was dissected, cultured ex vivo, and a cell population, MUPS‐1, were isolated from outgrowths. Gene and protein expression profiles of both the primary tumor and the derived there from cells were obtained by quantitative RT‐PCR and immunohistochemistry and included markers of epithelial, endothelial, and mesenchymal differentiation. To better define potential biomarkers, MUPS‐1 cells were additionally characterized by RNA sequencing analysis.

Results

Pathological analysis of primary tumor tissue revealed a sarcoma demonstrating multiple pathways of differentiation simultaneously with myxoid, fibrous, and osseous tissue. The isolated cells had a spindle cell‐like morphology, were maintained in culture for greater than 20 passages, and formed colonies in soft agar indicating tumorigenicity. The cells, similar to the primary tumor, were strongly positive for vimentin and moderately expressed alkaline phosphatase. RNA‐seq analysis revealed the tumor over‐expressed several genes compared to normal tissue, including components of the Notch signaling pathway, NOTCH3 and JAG1.

Conclusions

We have successfully established an undifferentiated pleomorphic sarcoma cell population, which will provide a valuable resource for studying fundamental processes and potentially serving as a platform for exploring therapeutic strategies for sarcomas.

Cancer/testis antigens expression during cultivation of melanoma and soft tissue sarcoma cells

BACKGROUND

Autologous dendritic cells (DC) loaded with tumor-associated antigens (TAAs) are a promising approach for anticancer immunotherapy. Polyantigen lysates appear to be an excellent source of TAAs for loading onto the patient's dendritic cells. Cancer/testis antigens (CTA) are expressed by a wide range of tumors, but are minimally expressed on normal tissues, and could serve as a universal target for immunotherapy. However, CTA expression levels can vary significantly in patients with the same tumor type. We proposed that patients who do not respond to DC-based therapy may have distinct features of the CTA expression profile on tumor cells.

PATIENTS AND METHODS

We compared the gene expression of the principal families CTA in 22 melanoma and 27 soft tissue and bone sarcomas cell lines (STBS), received from patients and used for DC vaccine preparation.

RESULTS

The majority (47 of 49, 95.9%) cell lines showed CTA gene activity. The incidence of gene expression of GAGE, NYESO1, MAGEA1, PRAME's was significantly different (adj. p < 0.05) between melanoma and sarcoma cell lines. The expression of the SCP1 gene was detected neither in melanoma cells nor in the STBS cells. Clustering by the gene expression profile revealed four different expression patterns. We found three main patterns types: hyperexpression of multiple CTA, hyperexpression of one CTA with almost no expression of others, and no expression of CTA. All clusters types exist in melanoma and sarcoma cell lines. We observed dependence of killing efficacy from the PRAME (rho = 0.940, adj. p < 0.01) expression during real-time monitoring with the xCELLigence system of the interaction between melanoma or sarcoma cells with the T-lymphocytes activated by the lysate of selected allogenous melanoma cell lines with high expression of CTA.

CONCLUSION

Our results demonstrate that one can use lysates from allogeneic melanoma cell lines as a source of CTA for DC load during the production of anticancer vaccines for the STBS treatment. Patterns of CTA expression should be evaluated as biomarkers of response in prospective clinical trials.

Using biology to guide the treatment of sarcomas and aggressive connective-tissue tumours

Sarcomas are a heterogeneous group of malignancies that arise from cells of a mesenchymal origin. Surgery forms the mainstay of the treatment of most patients with localized sarcoma and might be followed or preceded by chemotherapy and/or radiotherapy. In the metastatic setting, systemic treatments tend to improve survival and control symptoms. However, the adverse events and sometimes disappointing outcomes associated with these empirical approaches to treatment indicate a need for new approaches. The advent of next-generation sequencing (NGS) has enabled more targeted treatment of many malignancies based on the presence of specific alterations. NGS analyses of sarcomas have revealed the presence of many alterations that can be targeted using therapies that are already used in patients with other forms of cancer. In this Review, we describe the genomic alterations considered to define specific nosological subgroups of sarcoma and whose contribution to oncogenesis provides a biological rationale for the use of a specific targeted therapy. We also report several less successful examples that should guide researchers and clinicians to better define the extent to which the identification of driver molecular alterations should influence the development of novel treatments.

Characterization and Drug Sensitivity of a New High-Grade Myxofibrosarcoma Cell Line

Myxofibrosarcoma (MFS) belongs to the group of sarcoma tumors, which represent only 1% of the totality of adult tumors worldwide. Thus, given the rare nature of this cancer, this makes the availability of MFS cell lines difficult. In an attempt to partially fill this gap, we immortalized a primary culture of MFS (IM-MFS-1) and compared the cell morphology with patient’s tumor tissue. IM-MFS-1 was genetically characterized through a Comparative Genomic Hybridization (CGH) array and the mesenchymal phenotype was evaluated using Polymerase chain reaction (PCR) and immunofluorescence staining. Drug sensitivity for MFS therapies was monitored over time in cultures. We confirmed the conservation of the patient’s tumor cell morphology and of the mesenchymal phenotype. Conversely, the synthesis and expression of CD109, a TGFβ co-receptor used to facilitate the diagnosis of high-grade MFS diagnosis, was maintained constant until high cancer cell line passages. The CGH array revealed a complex karyotype with cytogenetic alterations that include chromosome regions associated with genes involved in tumor processes. Cytotoxicity assays show drug sensitivity constantly increased during the culture passages until a plateau was reached. In conclusion, we established and characterized a new MFS cell line that can be used for future preclinical and molecular studies on soft tissue sarcomas.

Sister Chromatid Exchange and Genomic Instability in Soft Tissue Sarcomas: Potential Implications for Response to DNA-Damaging Treatments

Sarcomas are rare heterogeneous malignancies of mesenchymal origin characterised by complex karyotypes but no specific abnormalities. Recurrence is common, and metastatic disease carries poor survival despite standard DNA-damaging radiotherapy or chemotherapy. DNA double-strand breaks (DSBs) are either repaired by mechanisms such as homologous recombination (HR) or result in cell death by apoptosis. Endogenous γH2AX formation and SCE formation are early and late events, respectively, and their levels are considered surrogate measures of genomic instability. Combined γH2AX and SCE analysis was used to evaluate endogenous DNA DSB levels (and their subsequent repair) in 9 primary sarcoma cell lines and compared with well-established commercial lines. All the sarcoma cell lines had elevated γH2AX and SCE levels, but there was no correlation between the DNA DSB frequency and subsequent SCE. Typically, radioresistant osteosarcoma cells had relatively low γH2AX frequency but high SCE counts suggestive of efficient DNA repair. Conversely, liposarcoma cells derived from a radiosensitive tumour had high H2AX but relatively lower SCE levels that may imply inefficient DNA DSB repair. To our knowledge, this is the first report that correlates H2AX and SCE levels in primary sarcoma cell lines and may provide insight into potential response to DNA-damaging treatments.

Sarcoma Spheroids and Organoids-Promising Tools in the Era of Personalized Medicine

Cancer treatment is rapidly evolving toward personalized medicine, which takes into account the individual molecular and genetic variability of tumors. Sophisticated new in vitro disease models, such as three-dimensional cell cultures, may provide a tool for genetic, epigenetic, biomedical, and pharmacological research, and help determine the most promising individual treatment. Sarcomas, malignant neoplasms originating from mesenchymal cells, may have a multitude of genomic aberrations that give rise to more than 70 different histopathological subtypes. Their low incidence and high level of histopathological heterogeneity have greatly limited progress in their treatment, and trials of clinical sarcoma are less frequent than trials of other carcinomas. The main advantage of 3D cultures from tumor cells or biopsy is that they provide patient-specific models of solid tumors, and they overcome some limitations of traditional 2D monolayer cultures by reflecting cell heterogeneity, native histologic architectures, and cell-extracellular matrix interactions. Recent advances promise that these models can help bridge the gap between preclinical and clinical research by providing a relevant in vitro model of human cancer useful for drug testing and studying metastatic and dormancy mechanisms. However, additional improvements of 3D models are expected in the future, specifically the inclusion of tumor vasculature and the immune system, to enhance their full ability to capture the biological features of native tumors in high-throughput screening. Here, we summarize recent advances and future perspectives of spheroid and organoid in vitro models of rare sarcomas that can be used to investigate individual molecular biology and predict clinical responses. We also highlight how spheroid and organoid culture models could facilitate the personalization of sarcoma treatment, provide specific clinical scenarios, and discuss the relative strengths and limitations of these models.

Primary Culture of Undifferentiated Pleomorphic Sarcoma: Molecular Characterization and Response to Anticancer Agents

Undifferentiated pleomorphic sarcoma (UPS) is an aggressive mesenchymal neoplasm with no specific line of differentiation. Eribulin, a novel synthetic microtubule inhibitor, has shown anticancer activity in several tumors, including soft tissue sarcomas (STS). We investigated the molecular biology of UPS, and the mechanisms of action of this innovative microtubule-depolymerizing drug. A primary culture from a patient with UPS was established and characterized in terms of gene expression. The activity of eribulin was also compared with that of other drugs currently used for STS treatment, including trabectedin. Finally, Western blot analysis was performed to better elucidate the activity of eribulin. Our results showed an upregulation of epithelial mesenchymal transition-related genes, and a downregulation of epithelial markers. Furthermore, genes involved in chemoresistance were upregulated. Pharmacological analysis confirmed limited sensitivity to chemotherapy. Interestingly, eribulin exhibited a similar activity to that of standard treatments. Molecular analysis revealed the expression of cell cycle arrest-related and pro-apoptotic-related proteins. These findings are suggestive of aggressive behavior in UPS. Furthermore, the identification of chemoresistance-related genes could facilitate the development of innovative drugs to improve patient outcome. Overall, the results from the present study furnish a rationale for elucidating the role of eribulin for the treatment of UPS.

Management and potentialities of primary cancer cultures in preclinical and translational studies

The use of patient-derived primary cell cultures in cancer preclinical assays has increased in recent years. The management of resected tumor tissue remains complex and a number of parameters must be respected to obtain complete sample digestion and optimal vitality yield. We provide an overview of the benefits of correct primary cell culture management using different preclinical methodologies, and describe the pros and cons of this model with respect to other kinds of samples. One important advantage is that the heterogeneity of the cell populations composing a primary culture partially reproduces the tumor microenvironment and crosstalk between malignant and healthy cells, neither of which is possible with cell lines. Moreover, the use of patient-derived specimens in innovative preclinical technologies, such as 3D systems or bioreactors, represents an important opportunity to improve the translational value of the results obtained. In vivo models could further our understanding of the crosstalk between tumor and other tissues as they enable us to observe the systemic and biological interactions of a complete organism. Although engineered mice are the most common model used in this setting, the zebrafish (Danio rerio) species has recently been recognized as an innovative experimental system. In fact, the transparent body and incomplete immune system of zebrafish embryos are especially useful for evaluating patient-derived tumor tissue interactions in healthy hosts. In conclusion, ex vivo systems represent an important tool for cancer research, but samples require correct manipulation to maximize their translational value.

Three-Dimensional Patient-Derived In Vitro Sarcoma Models: Promising Tools for Improving Clinical Tumor Management

Over the past decade, the development of new targeted therapeutics directed against specific molecular pathways involved in tumor cell proliferation and survival has allowed an essential improvement in carcinoma treatment. Unfortunately, the scenario is different for sarcomas, a group of malignant neoplasms originating from mesenchymal cells, for which the main therapeutic approach still consists in the combination of surgery, chemotherapy, and radiation therapy. The lack of innovative approaches in sarcoma treatment stems from the high degree of heterogeneity of this tumor type, with more that 70 different histopathological subtypes, and the limited knowledge of the molecular drivers of tumor development and progression. Currently, molecular therapies are available mainly for the treatment of gastrointestinal stromal tumor, a soft-tissue malignancy characterized by an activating mutation of the tyrosine kinase KIT. Since the first application of this approach, a strong effort has been made to understand sarcoma molecular alterations that can be potential targets for therapy. The low incidence combined with the high level of histopathological heterogeneity makes the development of clinical trials for sarcomas very challenging. For this reason, preclinical studies are needed to better understand tumor biology with the aim to develop new targeted therapeutics. Currently, these studies are mainly based on in vitro testing, since cell lines, and in particular patient-derived models, represent a reliable and easy to handle tool for investigation. In the present review, we summarize the most important models currently available in the field, focusing in particular on the three-dimensional spheroid/organoid model. This innovative approach for studying tumor biology better represents tissue architecture and cell–cell as well as cell–microenvironment crosstalk, which are fundamental steps for tumor cell proliferation and survival.

The Oncopig Cancer Model: An Innovative Large Animal Translational Oncology Platform

Despite an improved understanding of cancer molecular biology, immune landscapes, and advancements in cytotoxic, biologic, and immunologic anti-cancer therapeutics, cancer remains a leading cause of death worldwide. More than 8.2 million deaths were attributed to cancer in 2012, and it is anticipated that cancer incidence will continue to rise, with 19.3 million cases expected by 2025. The development and investigation of new diagnostic modalities and innovative therapeutic tools is critical for reducing the global cancer burden. Toward this end, transitional animal models serve a crucial role in bridging the gap between fundamental diagnostic and therapeutic discoveries and human clinical trials. Such animal models offer insights into all aspects of the basic science-clinical translational cancer research continuum (screening, detection, oncogenesis, tumor biology, immunogenicity, therapeutics, and outcomes). To date, however, cancer research progress has been markedly hampered by lack of a genotypically, anatomically, and physiologically relevant large animal model. Without progressive cancer models, discoveries are hindered and cures are improbable. Herein, we describe a transgenic porcine model—the Oncopig Cancer Model (OCM)—as a next-generation large animal platform for the study of hematologic and solid tumor oncology. With mutations in key tumor suppressor and oncogenes, TP53^R167H and KRAS^G12D, the OCM recapitulates transcriptional hallmarks of human disease while also exhibiting clinically relevant histologic and genotypic tumor phenotypes. Moreover, as obesity rates increase across the global population, cancer patients commonly present clinically with multiple comorbid conditions. Due to the effects of these comorbidities on patient management, therapeutic strategies, and clinical outcomes, an ideal animal model should develop cancer on the background of representative comorbid conditions (tumor macro- and microenvironments). As observed in clinical practice, liver cirrhosis frequently precedes development of primary liver cancer or hepatocellular carcinoma. The OCM has the capacity to develop tumors in combination with such relevant comorbidities. Furthermore, studies on the tumor microenvironment demonstrate similarities between OCM and human cancer genomic landscapes. This review highlights the potential of this and other large animal platforms as transitional models to bridge the gap between basic research and clinical practice.

Oncopig Soft-Tissue Sarcomas Recapitulate Key Transcriptional Features of Human Sarcomas

Human soft-tissue sarcomas (STS) are rare mesenchymal tumors with a 5-year survival rate of 50%, highlighting the need for further STS research. Research has been hampered by limited human sarcoma cell line availability and the large number of STS subtypes, making development of STS cell lines and animal models representative of the diverse human STS subtypes critical. Pigs represent ideal human disease models due to their similar size, anatomy, metabolism, and genetics compared to humans. The Oncopig encodes inducible KRAS^G12D and TP53^R167H transgenes, allowing for STS modeling in a spatial and temporal manner. This study utilized Oncopig STS cell line (fibroblast) and tumor (leiomyosarcoma) RNA-seq data to compare Oncopig and human STS expression profiles. Altered expression of 3,360 and 7,652 genes was identified in Oncopig STS cell lines and leiomyosarcomas, respectively. Transcriptional hallmarks of human STS were observed in Oncopig STS, including altered TP53 signaling, Wnt signaling activation, and evidence of epigenetic reprogramming. Furthermore, master regulators of Oncopig STS expression were identified, including FOSL1, which was previously identified as a potential human STS therapeutic target. These results demonstrate the Oncopig STS model’s ability to mimic human STS transcriptional profiles, providing a valuable resource for sarcoma research and cell line development.