Smoothened as a new therapeutic target for human osteosarcoma.

BACKGROUND: The Hedgehog signaling pathway functions as an organizer in embryonic development. Recent studies have demonstrated constitutive activation of Hedgehog pathway in various types of malignancies. However, it remains unclear how Hedgehog pathway is involved in the pathogenesis of osteosarcoma. To explore the involvement of aberrant Hedgehog pathway in the pathogenesis of osteosarcoma, we investigated the expression and activation of Hedgehog pathway in osteosarcoma and examined the effect of SMOOTHENED (SMO) inhibition. RESULTS: To evaluate the expression of genes of Hedgehog pathway, we performed real-time PCR and immunohistochemistry using osteosarcoma cell lines and osteosarcoma biopsy specimens. To evaluate the effect of SMO inhibition, we did cell viability, colony formation, cell cycle in vitro and xenograft model in vivo. Real-time PCR revealed that osteosarcoma cell lines over-expressed Sonic hedgehog, Indian hedgehog, PTCH1, SMO, and GLI. Real-time PCR revealed over-expression of SMO, PTCH1, and GLI2 in osteosarcoma biopsy specimens. These findings showed that Hedgehog pathway is activated in osteosarcomas. Inhibition of SMO by cyclopamine, a specific inhibitor of SMO, slowed the growth of osteosarcoma in vitro. Cell cycle analysis revealed that cyclopamine promoted G1 arrest. Cyclopamine reduced the expression of accelerators of the cell cycle including cyclin D1, cyclin E1, SKP2, and pRb. On the other hand, p21(cip1) wprotein was up-regulated by cyclopamine treatment. In addition, knockdown of SMO by SMO shRNA prevents osteosarcoma growth in vitro and in vivo. CONCLUSIONS: These findings suggest that inactivation of SMO may be a useful approach to the treatment of patients with osteosarcoma.

Diagnosing and discriminating between primary and secondary aneurysmal bone cysts.

Aneurysmal bone cysts (ABCs) are benign bony lesions frequently accompanied by multiple cystic lesions and aggressive bone destruction. They are relatively rare lesions, representing only 1% of bone tumors. The pathogenesis of ABCs has yet to be elucidated. In the present study, a series of 22 cases of primary and secondary ABC from patients treated in Department of Orthopedic Surgery, Kagoshima University Hospital (Kagoshima, Japan) from 2001-2015 were retrospectively analyzed. The average age at the time of diagnosis of primary ABC was 17.9 years. Intralesional curettage and artificial bone grafting were performed in the majority of the patients with primary ABC. The local recurrence rate following curettage for primary ABC was 18%, and the cause of local recurrence was considered to be insufficient curettage. Although no adjuvant therapy was administered during the surgeries, it may assist the prevention of local recurrence in certain cases. The cases of secondary ABC were preceded by benign bone tumors, including fibrous dysplasia, giant cell tumors, chondroblastoma and non-ossifying fibroma. The features of the secondary ABC typically reflected those of the preceding bone tumor. In the majority of cases, distinguishing the primary ABC from the secondary ABC was possible based on characteristic features, including age of the patient at diagnosis and the tumor location. In cases that exhibit ambiguous features, including a soft tissue mass or a thick septal enhancement on the preoperative magnetic resonance images, a biopsy must be obtained in order to exclude other types of aggressive bone tumors, including giant cell tumor, osteosarcoma and telangiectatic osteosarcoma.

Role of GOLPH3 and GOLPH3L in the proliferation of human rhabdomyosarcoma.

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.