Satoru Fukunaga

Enhanced suppression of pulmonary metastasis of malignant melanoma cells by combined administration of α-galactosylceramide and interleukin-18

α‐Galactosylceramide (α‐GalCer) shows antitumor effects by activating natural killer (NK) cells indirectly through stimulation of the secretion of cytokines by NKT cells, whereas interleukin (IL)‐18 shows antitumor effects by activating NK cells directly. In the present study, we examined the antitumor effect of the combined administration of α‐GalCer and IL‐18. An injection of NK cell‐sensitive mouse B16 melanoma cells into a mouse tail vein produced pulmonary metastasis. The daily administration of α‐GalCer or IL‐18 alone for 4 days starting 1 day after the injection of B16 melanoma cells markedly suppressed the number of pulmonary metastatic foci, and their combined administration enhanced the antitumor effect compared with single administration. The antitumor effect of their combined administration was completely abolished by treatment of mice with anti‐asialo GM1 serum, which depletes NK cells but not NKT cells. Combined administration of α‐GalCer and IL‐18 enhanced the cytotoxicity of NK cells and increased the number of NK cells in the lung. Analysis of NKT cell‐dependent and NK cell‐independent secretion of cytokines, to which NK cells can respond, showed that the administration of α‐GalCer increased the secretion of IL‐2, IL‐4, interferon‐γ, IL‐12, granulocyte‐macrophage colony‐stimulating factor, tumor necrosis factor‐α, and IL‐10, and the combined administration of α‐GalCer and IL‐18 enhanced the secretion of IL‐2, IL‐4, interferon‐γ, and granulocyte‐macrophage colony‐stimulating factor further but only slightly. These results show that IL‐18 in combination with α‐GalCer exerts an antitumor effect on NK cell‐sensitive tumors primarily by the direct stimulation of NK cells by IL‐18 and the indirect stimulation of NK cells by α‐GalCer through its activation of NKT cells. (Cancer Sci 2008; 99: 113–120)

Downregulation of matrix metalloproteinase-9 mRNA by valproic acid plays a role in inhibiting the shedding of MHC class I-related molecules A and B on the surface of human osteosarcoma cells

Valproic acid, a histone deacetylase inhibitor, increases the expression of cell surface MHC class I-related chain molecules (MICs) A and B (MICA and B) in osteosarcoma cells and decreases their secretion of soluble MICA and MICB, which are produced by the proteolytic cleavage of cell surface MICs. Osteosarcoma cells have been reported to produce high levels of matrix metalloproteinase (MMP)-2 and -9. In this study, we investigated the involvement of MMP-2 and -9 in the inhibitory action of valproic acid (VPA) on the proteolytic cleavage of cell surface MICs using the U-2 OS and SaOS-2 osteosarcoma cell lines. VPA caused a marked decrease in the expression of MMP-9 mRNA in the U-2 OS and SaOS-2 cells and in the expression of MMP-2 mRNA in the U-2 OS cells, but only a slight decrease in the expression of MMP-2 mRNA in the SaOS-2 cells. The transfection of small interfering RNA (siRNA) for MMP-9 decreased the secretion of soluble MICA and MICB by both U-2 OS and SaOS-2 cells, but that of siRNA for MMP-2 did not. The present study therefore demonstrates that the downregulation of MMP-9 mRNA by VPA plays a role in the inhibitory action of VPA on the secretion of soluble MICA and MICB in osteosarcoma cells.

Valproic acid cooperates with hydralazine to augment the susceptibility of human osteosarcoma cells to Fas- and NK cell-mediated cell death

We investigated the effects of valproic acid (VPA), a histone deacetylase inhibitor, in combination with hydralazine, a DNA methylation inhibitor, on the expression of cell-surface Fas and MHC-class I-related chain molecules A and B (MICA and B), the ligands of NKG2D which is an activating receptor of NK cells, and on production of their soluble forms in HOS, U-2 OS and SaOS-2 human osteosarcoma cell lines. We also examined the susceptibility of these cells to Fas- and NK cell-mediated cell death. VPA did not increase the expression of Fas on the surface of osteosarcoma cells, while hydralazine did, and the combination of VPA with hydralazine increased the expression of cell-surface Fas. In contrast, the combination of VPA with hydralazine did not increase the production of soluble Fas by osteosarcoma cells. Both VPA and hydralazine increased the expression of cell-surface MICA and B in osteosarcoma cells, and their combination induced a greater increase in their expression. VPA inhibited the production of both soluble MICA and MICB by osteosarcoma cells while hydralazine produced no effect. Both VPA and hydralazine enhanced the susceptibility of osteosarcoma cells to Fas- and NK cell-mediated cell death and the combination of VPA with hydralazine further enhanced the effects. The present results suggest that combined administration of VPA and hydrazine is valuable for enhancing the therapeutic effects of immunotherapy for osteosarcomas.

A rare case of clear cell sarcoma with 4 types of EWSR1-ATF1 fusions detected not in primary site but in metastatic site.

Clear cell sarcoma is a unique tumor which has EWSR1-ATF1 or EWSR1-CREB1 fusion. Several patterns of EWSR1-ATF1 fusion are observed in clear cell sarcoma. Since type 5-7 fusions were reported recently, they are classified as type 1-7. We examined EWSR1-ATF1 and EWSR1-CREB1 fusions in a single case of clear cell sarcoma with lung metastasis in a 36-year-old Japanese man. As a result, we found only type 1 EWSR1-ATF1 fusion in the primary site, but 4 types of EWS-ATF1 fusion (type 1, 2, 5, 6) were detected in the metastatic site. These 4 types of fusion were completely identical to the recent report, but the case had the same fusion patterns in both primary and metastatic sites. In our case, increased splicing activity in the EWSR1-ATF1 fusion might be acquired at the metastatic site. There is another possibility that metastasis might develop through the increased splicing activity in the fusion.

Posterior interosseous nerve palsy caused by synovial chondromatosis arising in the annular periradial recesses of the elbow

We present a rare case report of a patient who presented with posterior interosseous nerve palsy caused by synovial chondromatosis. Synovial chondromatosis arising in the annular periradial recesses of the elbow joint was detected, and the mass developed two major portions constricted with the annular ligament. After surgical resection, posterior interosseous nerve palsy fully recovered and there was no recurrence of the lesion of synovial chondromatosis.

Usefulness of PET/CT for diagnosis of periosteal chondrosarcoma of the femur: A case report

Periosteal chondrosarcoma is an extremely rare low-grade malignant cartilaginous tumor arising from the external bone surface. Diagnosis of periosteal chondrosarcomas may be challenging, since this condition closely resembles periosteal chondromas. It has been reported that positron emission tomography (PET) is useful in distinguishing benign from malignant cartilaginous tumors using a maximum standardized uptake value (SUVmax) cut-off of 2.0 or 2.3. This report presents the case of a 40-year-old female with an 18-month history of a tender mass in the left distal femur. Radiological findings demonstrated periosteal buttressing. Magnetic resonance imaging (MRI) revealed a chondrogenic tumor of 3 cm in size developing from the external bone surface. It was difficult to differentiate periosteal chondrosarcoma from periosteal chondroma on the basis of size and the radiological and MRI findings. PET/computed tomography (CT) revealed abnormal linear uptake with an SUVmax of 2.7, indicating a malignant tumor. A diagnosis of periosteal chondrosarcoma was made, and wide resection was performed. Tumor histology was consistent with grade II chondrosarcoma. PET/CT is thus useful in differentiating periosteal chondrosarcoma from periosteal chondroma.