Establishment of a novel clear cell sarcoma cell line (Hewga-CCS), and investigation of the antitumor effects of pazopanib on Hewga-CCS

Abstract

BackgroundClear cell sarcoma (CCS) is a therapeutically unresolved, aggressive, soft tissue sarcoma (STS) that predominantly affects young adults. This sarcoma is defined by t(12;22)(q13;q12) translocation, which leads to the fusion of Ewing sarcoma gene (EWS) to activating transcription factor 1 (ATF1) gene, producing a chimeric EWS-ATF1 fusion gene. We established a novel CCS cell line called Hewga-CCS and developed an orthotopic tumor xenograft model to enable comprehensive bench-side investigation for intensive basic and preclinical research in CCS with a paucity of experimental cell lines.MethodsHewga-CCS was derived from skin metastatic lesions of a CCS developed in a 34-year-old female. The karyotype and chimeric transcript were analyzed. Xenografts were established and characterized by morphology and immunohistochemical reactivity. Subsequently, the antitumor effects of pazopanib, a recently approved, novel, multitargeted, tyrosine kinase inhibitor (TKI) used for the treatment of advanced soft tissue sarcoma, on Hewga-CCS were assessed in vitro and in vivo.ResultsHewga-CCS harbored the type 2 EWS-ATF1 transcript. Xenografts morphologically mimicked the primary tumor and expressed S-100 protein and antigens associated with melanin synthesis (Melan-A, HMB45). Pazopanib suppressed the growth of Hewga-CCS both in vivo and in vitro. A phospho-receptor tyrosine kinase array revealed phosphorylation of c-MET, but not of VEGFR, in Hewga-CCS. Subsequent experiments showed that pazopanib exerted antitumor effects through the inhibition of HGF/c-MET signaling.ConclusionsCCS is a rare, devastating disease, and our established CCS cell line and xenograft model may be a useful tool for further in-depth investigation and understanding of the drug-sensitivity mechanism.

Functional and therapeutic relevance of hepatocyte growth factor/c‐MET signaling in synovial sarcoma

“…Successful development of personalized molecular targeted therapy is dependent on identification of targets that are directly involved in tumorigenesis and tumor progression. HGF/c‐MET signaling reportedly has an important role in the development of several human cancers and in drug resistance in cancer cells . In the present study, we found that c‐MET‐activated Yamato‐SS cells were highly addicted to autocrine HGF/c‐MET signaling and exhibited higher anchorage‐independent growth ability and lesser sensitivity to chemotherapies than did c‐MET‐inactivated SYO‐1 or HS‐SY‐II cells.…”

“…HGF/c-MET signaling reportedly has an important role in the development of several human cancers and in drug resistance in cancer cells. (10)(11)(12)(13)(19)(20)(21)(22)(23)(30)(31)(32)(33)(34)(35) In the present study, we found that c-MET-activated Yamato-SS cells were highly addicted to autocrine HGF/c-MET signaling and exhibited higher anchorage-independent growth ability and lesser sensitivity to chemotherapies than did c-MET-inactivated SYO-1 or HS-SY-II cells. These results suggested that HGF/c-MET signaling was one of the essential factors for tumorigenesis or tumor progression in SS and raised the possibility that a subset of SS driven by this signaling might be highly aggressive and intractable.…”

“…Prior publications have suggested that fusion genes and cellular origins were crucial for determining and maintaining the tumor phenotype in translocation‐related malignancies . c‐MET is also frequently activated in translocation‐related soft tissue sarcomas such as alveolar rhabdomyosarcoma and clear cell sarcoma . Alveolar rhabdomyosarcoma is characterized by a chromosomal translocation t(2,13)(q35;q14) generating the PAX3‐FOXO1 (also known as FKHR ) fusion gene.…”

“…(28,41,42) c-MET is also frequently activated in translocation-related soft tissue sarcomas such as alveolar rhabdomyosarcoma and clear cell sarcoma. (22,23,43) Alveolar rhabdomyosarcoma is characterized by a chromosomal translocation t(2,13)(q35;q14) generating the PAX3-FOXO1 (also known as FKHR) fusion gene. It has been demonstrated that the expression of c-MET correlated significantly with PAX3-FOXO1 expression, indicating that c-MET was a downstream target of PAX3-FOXO1 in alveolar rhabdomyosarcoma.…”

“…(16)(17)(18) Combined overexpression of HGF and c-MET is observed in numerous soft tissue sarcomas such as epithelioid sarcomas, malignant peripheral nerve sheath tumors, and clear cell sarcomas, and HGF can activate c-MET in an autocrine manner in these tumors. (19)(20)(21)(22)(23) It has been reported that co-expression of HGF and c-MET was also frequently observed in SS clinical samples and was correlated with a poor prognosis. (24)(25)(26)(27) However, little is known about the function of HGF/c-MET signaling in SS and the antitumor effects of c-MET inhibitors on SS.…”