Establishment and characterization of NCC-SS4-C1: a novel patient-derived cell line of synovial sarcoma

Synovial Sarcoma Preclinical Modeling: Integrating Transgenic Mouse Models and Patient-Derived Models for Translational Research

Synovial sarcomas (SyS) are rare malignant tumors predominantly affecting children, adolescents, and young adults. The genetic hallmark of SyS is the t(X;18) translocation encoding the SS18-SSX fusion gene. The fusion protein interacts with both the BAF enhancer and polycomb repressor complexes, and either activates or represses target gene transcription, resulting in genome-wide epigenetic perturbations and altered gene expression. Several experimental in in vivo models, including conditional transgenic mouse models expressing the SS18-SSX fusion protein and spontaneously developing SyS, are available. In addition, patient-derived xenografts have been estab-lished in immunodeficient mice, faithfully reproducing the complex clinical heterogeneity. This review focuses on the main molecular features of SyS and the related preclinical in vivo and in vitro models. We will analyze the different conditional SyS mouse models that, after combination with some of the few other recurrent alterations, such as gains in BCL2, Wnt-β-catenin signaling, FGFR family, or loss of PTEN and SMARCB1, have provided additional insight into the mechanisms of synovial sarcomagenesis. The recent advancements in the understanding of SyS biology and improvements in preclinical modeling pave the way to the development of new epigenetic drugs and immunotherapeutic approaches conducive to new treatment options.

Establishment and characterization of NCC-SS5-C1: a novel patient-derived cell line of synovial sarcoma

Synovial sarcoma (SS) is a rare and aggressive mesenchymal malignancy driven by a unique chromosomal translocation that generates the expression of the SS18:SSX fusion protein. It occurs at almost any anatomical site and most commonly in young adults. The standard curative treatment for primary SS is a wide surgical resection combined with radiotherapy and/or neoadjuvant chemotherapy. The prognosis of SS varies among patients, with the 5 years survival rate ranging from 50 to 60% in adults and 90% in children. Although patient-derived cell lines are a useful resource for the development of new therapies, only a few are available from public cell banks. Therefore, this study aimed to establish and characterize a novel SS cell line. We successfully established a novel cell line, NCC-SS5-C1, harboring an SS18-SSX1 fusion gene. NCC-SS5-C1 cells demonstrated constant growth and invasion ability. We performed integrative drug screening using eight SS cell lines, including NCC-SS5-C1 cells, and examined the response spectrum of existing anticancer agents. We conclude that NCC-SS5-C1 is a useful resource for studying SS.

Establishment and characterization of NCC-UPS3-C1: a novel patient-derived cell line of undifferentiated pleomorphic sarcoma

Undifferentiated pleomorphic sarcoma (UPS), previously termed malignant fibrous histiocytoma, is one of the most aggressive sarcomas with no identifiable line of differentiation. Although the molecular mechanism of oncogenesis in UPS has not been clarified, radiation exposure is considered to be a risk factor in the development of UPS. In the treatment of UPS, surgical treatment remains the most important modality. While chemotherapy is considered in unresectable or metastatic cases, UPS is known to be refractory to conventional chemotherapy, leading to an unfavorable prognosis. To improve the clinical outcome of this condition, novel treatment methods are urgently needed. Patient-derived cell lines are essential tools in preclinical studies. However, owing to the rarity of UPS, only four UPS cell lines are publicly available. Thus, we established a novel UPS cell line, NCC-UPS3-C1, using a surgically resected tumor from a patient with radiation-associated UPS. NCC-UPS3-C1 cells had multiple genomic deletions including the tumor suppressor genes CDKN2A and CDKN2B. NCC-UPS3-C1 cells demonstrated constant growth, spheroid formation, and aggressive invasion ability. We also conducted a screening test using 214 drugs and identified that the histone deacetylase inhibitor, romidepsin, is highly effective on NCC-UPS3-C1 cells. Thus, we concluded that the NCC-UPS3-C1 cell line is a useful tool in preclinical studies for UPS.