Kenichi Kitazoe

Myeloma Cell-Osteoclast Interaction Enhances Angiogenesis Together with Bone Resorption: A Role for Vascular Endothelial Cell Growth Factor and Osteopontin

Purpose: Similar to osteoclastogenesis, angiogenesis is enhanced in the bone marrow in myeloma in parallel with tumor progression. We showed previously that myeloma cells and osteoclasts are mutually stimulated to form a vicious cycle to lead to enhance both osteoclastogenesis and tumor growth. The present study was undertaken to clarify whether myeloma cell-osteoclast interaction enhances angiogenesis and whether there is any mutual stimulation between osteoclastogenesis and angiogenesis. Experimental Design: Myeloma cells and monocyte-derived osteoclasts were cocultured, and angiogenic activity produced by the cocultures was assessed with in vitro vascular tubule formation assays and human umbilical vascular endothelial cell (HUVEC) migration and survival. Osteoclastogenic activity was determined with rabbit bone cell cultures on dentine slices. Results: Myeloma cells and osteoclasts constitutively secrete proangiogenic factors, vascular endothelial growth factor (VEGF) and osteopontin, respectively. A cell-to-cell interaction between myeloma cells and osteoclasts potently enhanced vascular tubule formation. Blockade of both VEGF and osteopontin actions almost completely abrogated such vascular tubule formation as well as migration and survival of HUVECs enhanced by conditioned medium from cocultures of myeloma cells and osteoclasts. Furthermore, these factors in combination triggered the production of osteoclastogenic activity by HUVEC. Conclusions: Osteoclast-derived osteopontin and VEGF from myeloma cells cooperatively enhance angiogenesis and also induce osteoclastogenic activity by vascular endothelial cells. These observations suggest the presence of a close link between myeloma cells, osteoclasts, and vascular endothelial cells to form a vicious cycle between bone destruction, angiogenesis, and myeloma expansion.

Therapy with bortezomib plus dexamethasone induces osteoblast activation in responsive patients with multiple myeloma.

Bortezomib is a novel proteasome inhibitor that has shown marked antitumor effects in patients with multiple myeloma (MM). We evaluated the feasibility and efficacy of bortezomib plus dexamethasone (BD) therapy and assessed bone metabolism in relapsed or refractory MM. Fourteen patients received 1.3 mg/m2 bortezomib on days 1, 4, 8, and 11 along with 20 mg/dose of dexamethasone on days 1, 2, 4, 5, 8, 9, 11, and 12 in a 21-day cycle. After 1 to 3 cycles of BD therapy, 9 patients (64%) achieved an objective response (5 very good partial responses and 4 partial responses). Notably, a rapid increase in the serum concentration of alkaline phosphatase (ALP) was observed in 6 of the treatment-responsive patients. Moreover, serum levels of bone-formation markers (bone-specific ALP and osteocalcin) significantly increased in 5 and 2 responsive patients, respectively. Radiographic examination showed improvement in bone lesions, suggesting that BD therapy induces osteoblast activation in responders. Adverse events included thrombocytopenia of grades 1 to 3, peripheral neuropathy of grades 1 to 2, and grade 3 ileus and were transient and manageable. Although severe lung injury has been reported among Japanese patients treated with bortezomib, no pulmonary complications were observed during BD therapy. Our results suggest that BD therapy is a safe and promising therapeutic approach for Japanese patients with MM.

Valproic acid exerts anti-tumor as well as anti-angiogenic effects on myeloma

Multiple myeloma is still an incurable disease, most commonly occurring in the elderly. The myeloma-induced bone marrow microenvironment protects myeloma cells from drug-induced apoptosis. Therefore, the development of novel and tolerable therapeutic alternatives to overcome the drug resistance is an important clinical issue. Valproic acid (VPA), a safe and widely used anti-epileptic agent, is revisited as a class I- and IIa-specific histone deacetylase inhibitor. In the present study, we evaluated the effect as well as a mechanism of actions of VPA on myeloma cell growth and survival, with special reference to the myeloma-induced bone marrow microenvironment. VPA at therapeutic concentrations for epilepsy induced cell death in primary CD138-positive myeloma cells as well as myeloma cell lines, but not in CD138-negative bone marrow cells. VPA suppressed osteoclastogenesis as well as osteoclast-mediated myeloma cell growth. VPA also inhibited vascular tubule formation enhanced by co-cultures of myeloma cells and osteoclasts in concert with thalidomide. In addition, VPA induced both caspase-dependent and -independent cell death in myeloma cells, and potentiated the anti-myeloma effects of melphalan and dexamethasone. Collectively, VPA is suggested to exert multi-factorial anti-myeloma actions, and may serve as a safe adjuvant to be included in conventional chemotherapies against myeloma.

Malignant B-Lymphoid Cells with Bone Lesions Express Receptor Activator of Nuclear Factor-κB Ligand and Vascular Endothelial Growth Factor to Enhance Osteoclastogenesis

Purpose: Receptor activator of nuclear factor-κB ligand (RANKL) is a key mediator of osteoclastogenesis. Because certain types of tumor cells aberrantly express RANKL, and because bone destruction also develops in B-cell lymphomas of bone origin, we investigated RANKL expression and the mechanisms of osteoclastogenesis in B-lymphoid neoplasms. Experimental Design and Results: Immunohistochemistry of bone specimens resected from patients with primary B-cell lymphoma of bone with bone destruction revealed that lymphoma cells express RANKL as well as vascular endothelial cell growth factor (VEGF). The tumor cells isolated from the bone specimens enhanced osteoclastogenesis in vitro. In contrast, B-cell lymphoma infiltrating to the bone marrow without bone destruction did not express RANKL. Both RANKL and VEGF were expressed by a portion of B-lymphoid cell lines, including Daudi and IM-9. These RANKL-expressing tumor cells enhanced osteoclastogenesis from RAW264.7 cells and human monocyte-derived preosteoclasts in the absence of stromal cells/osteoblasts in a RANKL-dependent manner. Furthermore, conditioned media from Daudi cells enhanced transmigration of preosteoclasts that was inhibited by anti-VEGF antibody, suggesting that tumor cell–derived VEGF mediates recruitment of osteoclast precursors. Moreover, cocultures of B-lymphoid cell lines with osteoclasts enhanced the growth of B-lymphoid cells. Conclusions: Some malignant B cells aberrantly express functional RANKL as well as VEGF to enhance osteoclastogenesis. The coexpression of RANKL and VEGF may also contribute to the close cellular interactions with osteoclastic cells, thereby forming a vicious cycle between osteoclastic bone destruction and tumor expansion in bone.

Fatal continuous pleural and peritoneal hemorrhage in a patient with differentiated liposarcoma of retroperitoneal origin

39歳男性.腹痛と右側胸部腫瘤のため入院.右側胸部の皮下と右肺尖部に腫瘍がみられたほか,右腎周囲後腹膜の腫脹と腹腔内リンパ節の腫大を認めた.入院後,血性の胸腹水が急速に増加し,化学療法の効果なく,入院24日目に出血性ショックのため死亡した.剖検後の組織学的検討により,後腹膜原発の脱分化型脂肪肉腫と診断した.脱分化型脂肪肉腫は稀な疾患で,後腹膜に好発するが,本例のような体腔内出血による急激な転帰の報告はない.