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The Hedgehog pathway functions as an organizer in embryonic development. Recent studies have shown that mutation of the PTCH1 gene involved in the Hedgehog path-way affects rhabdomyosarcoma development. However, the expression of Hedgehog pathway molecules in human rhabdomyosarcoma cells has not been well clarified. In addition, the effect of pharmacological inhibition of the Hedgehog pathway is not known. We investigated the expression of the genes involved in the Hedgehog pathway using human rhabdomyosarcoma cell lines and biopsy specimens. Further, we evaluated the effect of pharmacological inhibition of the Hedgehog pathway using cyclopamine or GANT61 by WST assay, cell proliferation assay and cell death detection assay. Real-time PCR revealed that human rhabdomyosarcoma cell lines and biopsy specimens overexpressed the following genes: Sonic hedgehog, Indian hedgehog, Desert hedgehog, PTCH1, SMO, GLI1, GLI2 and ULK3. Immunohistochemistry revealed that rhabdomyosarcoma cell lines and biopsy specimens expressed SMO and GLI2. Inhibition of SMO by cyclopamine slowed the growth of human rhabdomyosarcoma cell lines. Similarly, inhibition of GLI by GANT61 slowed the growth of human rhabdomyosarcoma cell lines. Inhibition of cell proliferation and apoptotic cell death together prevented the growth of rhabdomyosarcoma cells by cyclopamine and GANT61 treatment. Our findings suggest that pharmacological inhibition of the Hedgehog pathway may be a useful approach for treating rhabdomyosarcoma patients.

GOLPH3 was originally identified by proteomic analyses of Golgi proteins localized in the trans-Golgi network. Recently, it was reported that GOLPH3 is up-regulated in various types of malignancies, including melanoma, colon cancer and lung cancer. However, the mechanism through which GOLPH3 is involved in the pathogenesis of rhabdomyosarcoma remains unidentified. In order to explore the function of GOLPH3 and its isoform, GOLPH3L, in the pathogenesis of rhabdomyosarcoma, we investigated the expression and knockdown effects of GOLPH3 and GOLPH3L in human rhabdomyosarcoma. Western blot analysis and real-time PCR revealed that human rhabdomyosarcoma cell lines and biopsy specimens exhibited an increased expression of GOLPH3 and GOLPH3L. GOLPH3 and GOLPH3L knockdown by siRNA prevented the proliferation of human rhabdomyosarcoma cell lines. In addition, double-knockdown of GOLPH3 and GOLPH3L also prevented the proliferation of rhabdomyosarcoma cell lines. Our findings improve the understanding of rhabdomyosarcoma pathogenesis and suggest that the knockdown of GOLPH3 or GOLPH3L may be an effective treatment for rhabdomyosarcoma.

The Notch pathway regulates a broad spectrum of cell fate decisions and differentiation processes during fetal and postnatal development. In addition, the Notch pathway plays an important role in controlling tumorigenesis. However, the role of RBPJ, a transcription factor in the Notch pathway, in the development of tumors is largely unknown. In this study, we focused on the role of RBPJ in the pathogenesis of rhabdomyosarcoma (RMS). Our data showed that Notch pathway genes were upregulated and activated in human RMS cell lines and patient samples. Inhibition of the Notch pathway by a csecretase inhibitor (GSI) decreased the in vitro proliferation of RMS cells. Knockdown of RBPJ expression by RNAi inhibited the anchorage-independent growth of RMS cells and the growth of xenografts in vivo. Additionally, overexpression of RBPJ promoted the anchorage-independent growth of RMS cells. Further, we revealed that RBPJ regulated the cell cycle in RMS xenograft tumors and decreased proliferation. Our findings suggest that RBPJ regulates the RMS growth, and that the inhibition of RBPJ may be an effective therapeutic approach for patients with RMS.