Incretin accelerates platelet-derived growth factor-BB-induced osteoblast migration via protein kinase A: The upregulation of p38 MAP kinase.

Incretins, including glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP), secreted from enteroendocrine cells after food ingestion, are currently recognized to regulate glucose metabolism through insulin secretion. We previously demonstrated that platelet-derived growth factor-BB (PDGF-BB) induces the migration of osteoblast-like MC3T3-E1 cells through mitogen-activated protein (MAP) kinases, including p38 MAP kinase. In the present study, we investigated whether or not incretins affect the osteoblast migration. The PDGF-BB-induced cell migration was significantly reinforced by GLP-1, GIP or cAMP analogues in MC3T3-E1 cells and normal human osteoblasts. The upregulated migration by GLP-1 or cAMP analogues was suppressed by H89, an inhibitor of protein kinase A. The amplification by GLP-1 of migration induced by PDGF-BB was almost completely reduced by SB203580, a p38 MAP kinase inhibitor in MC3T3-E1 cells and normal human osteoblasts. In addition, GIP markedly strengthened the PDGF-BB-induced phosphorylation of p38 MAP kinase. Exendin-4, a GLP-1 analogue, induced Rho A expression and its translocation from cytoplasm to plasma membranes in osteoblasts at the epiphyseal lines of developing mouse femurs in vivo. These results strongly suggest that incretins accelerates the PDGF-BB-induced migration of osteoblasts via protein kinase A, and the up-regulation of p38 MAP kinase is involved in this acceleration. Our findings may highlight the novel potential of incretins to bone physiology and therapeutic strategy against bone repair.

KRN5500, a spicamycin derivative, exerts anti-myeloma effects through impairing both myeloma cells and osteoclasts.

The spicamycin analogue KRN5500 alters glycoprotein processing and induces damage in the endoplasmic reticulum (ER)-Golgi apparatus in cancer cells. In the present study, we explored the cytotoxic effects of KRN5500 on multiple myeloma (MM) cells and the bone marrow microenvironment with special reference to ER stress. Cell proliferation assay showed that KRN5500 induced G1 arrest and apoptosis in MM cells in a time- and dose-dependent manner. KRN5500 enhanced ER stress independently of caspase activation in MM cells. This cell death was observed even in the presence of bone marrow stroma cells or osteoclasts. Notably, KRN5500 induced cell death also in osteoclasts. In vivo effects of KRN5500 were evaluated using two xenograft models established in severe combined immunodeficient (SCID) mice by either subcutaneous injection of RPMI 8226 cells or intra-bone injection of INA-6 cells to subcutaneously implanted rabbit bones (SCID-rab model). KRN5500 significantly inhibited tumour growth in both animal models, and decreased the number of osteoclasts, which resulted in prevention of bone destruction in the SCID-rab model. These results suggest that KRN5500 exerts anti-MM effects through impairing both MM cells and osteoclasts. Therefore, this unique mechanism of KRN5500 might be a useful therapeutic option in patients with MM.

Marked improvement of platelet transfusion refractoriness after bortezomib therapy in multiple myeloma.

We report a patient with refractory multiple myeloma (MM) who developed platelet transfusion refractoriness (PTR). A 61-year-old woman was diagnosed with MM in July 2003. She underwent high-dose chemotherapy followed by autologous stem cell transplantation, and achieved a very good partial response. However, she relapsed in June 2006, and was referred to our hospital in October of the same year. Laboratory examinations showed pancytopenia and increased plasma cells in the peripheral blood. Platelet transfusions from random donors became ineffective, and anti-HLA class I antibody (83.8% positive) was detected in the serum by flow cytometry assay (Flow PRA). Therefore, she was considered to have developed PTR due to anti-HLA class I antibody caused by the previous blood transfusions. She was transfused with HLA-matched platelets, and then treated with bortezomib plus dexamethasone (BD) for refractory MM. The serum IgG level decreased from 7,451 to 1,735 mg/dL, and HLA class I antibody was markedly decreased to 1.9%. In addition, platelet transfusion from random donors showed clinical effects after BD therapy. This case suggests that bortezomib might be effective in different types of immune disease by inhibiting allo-reactive antibody.

[Clinical analysis of eight patients with primary follicular lymphoma in the duodenum].

We performed a clinical analysis on 8 patients with primary follicular lymphoma in the duodenum taken from among 26 cases of primary gastrointestinal malignant lymphoma treated in our division. The median age was 60 years (range 48 to 82 yr). The ratio of males to females was 4:4. The chief complaints were no symptoms in 4 cases, heartburn in 2 cases, lower abdominal pain in 1 case, and back pain in 1 case. All patients were in clinical stage I EA. Gastroendoscopic findings showed multiple whitish granules around the ampulla of Vater in all patients. Involvement of the site in 6 cases was only located at the second portion; lesions in the other 2 cases were located at the second portion, and at the third portion or fourth portion, respectively. A histological study showed follicular lymphoma grade 1, and an immunohistological study demonstrated that the lymphoma cells were positive for CD79a, CD10, CD20, and bcl-2. Five patients were positive for the FISH analysis fusion signal of IgH/bcl-2 genes. Rituximab with CHOP therapy was performed for 7 patients. Seven patients are currently alive, and one died of uterine cancer. At the medium-term 39 month-follow-up, 7 patients were in complete remission, and 1 patient was in partial remission. Rituximab with CHOP (CVP) therapy is a possible treatment for primary follicular lymphoma in the duodenum. Further consideration of appropriate therapy for this disease might be necessary.

TRAIL expression up-regulated by interferon-gamma via phosphorylation of STAT1 induces myeloma cell death.

BACKGROUND: Although the cellular and molecular biological effects of interferon (IFN)-alpha have been well-investigated, the effects of IFN-gamma are less understood. MATERIALS AND METHODS: Eleven human myeloma cell lines with various myeloma-specific chromosomal translocations and overexpression of oncogenes were cultured with 1000 U/ml of IFN-gamma. In the KMS-20 cells, which showed growth inhibition due to IFN-gamma, trail expression, status of the Janus kinase (JAK)/STAT pathway were analyzed. RESULTS: KMS-20 cells showed marked up-regulation of trail, activation of STAT1 and TRAIL hyperproduction induced by IFN-gamma. CONCLUSION: The effects of IFN-gamma on growth inhibition of KMS-20 cells were characterized by activation of the JAK/STAT signalling pathway, particularly STAT1 phosphorylation, enhanced secretion of TRAIL, and auto/paracrine usage of secreted TRAIL to induce apoptotic cell death. From these results, IFN-gamma may be considered one of the drugs to be used in future multidrug chemotherapeutic regimens for myeloma patients.