The effect of psoralen plus ultraviolet A in vitro in HUT-78 enhances by 5-aminolevulinic acid.

BACKGROUND: Sezary syndrome and mycosis fungoides are forms of cutaneous T-cell lymphoma, and in the early stage of these diseases psoralen plus ultraviolet A (PUVA) is one of the treatments of choice. Photodynamic therapy using 5-aminolevulinic acid (ALA-PDT) is an effective, non-invasive, and safe treatment for most superficial skin cancers. In order to obtain greater efficacy of PUVA, we investigated the synergistic anti-tumor effects of ALA-PDT and PUVA using 8-methoxypsoralen (8-MOP) and a UVA lamp. METHODS: The in vitro effects of PUVA and ALA-PDT and their combination in HUT-78 cell line from human SS were determined by MTT assay. RESULTS: In our results, cell proliferation compared with controls was inhibited to 53.2% with UVA alone, 52.3% with 1 microM 8-MOP, 43.8% with 100 microM ALA, and 19.2% with combined 8-MOP and ALA. CONCLUSION: Combined use of ALA and PUVA using 8-MOP and UVA lamps, which are widespread in Japan, had a strong anti-tumor effect in vitro. Combined treatment with ALA-PDT and PUVA using a UVA lamp appears to have a strong treatment effect.

p27KIP1 and GATA-1 are potential downstream molecules in activin A-induced differentiation and apoptosis pathways in CML cells.

p27KIP1 is known as a regulator of cellular differentiation and apoptosis in human cancer cells. We have previously reported that human chronic myeloid leukemia (CML) KU812 and K562 cells show inhibited cellular proliferation in response to treatment with activin A, a member of TGF-beta superfamily. Apoptosis and erythroid differentiation can be induced in KU812 and K562 cells, respectively. We report herein that activin A induced the expression of p27KIP1 in CML cells along with the induction of cellular differentiation and apoptosis. There are putative binding sequences of erythroid-related transcription factor GATA-1 in the promoter region of the human p27KIP1 gene. Expression of GATA-1 protein in activin A-treated KU812 and K562 cells showed dissimilar regulation in these two cell lines. Induction of p27KIP1 was commonly observed, but it did not correspond to the expression levels of GATA-1 in either line of activin A-treated CML cells. In addition, ERK protein was rapidly and transiently activated with activin A in both types of CML cells, suggesting that phosphorylation of ERK is required for activin A signaling in CML cells. These results indicate that both p27KIP1 induction and regulation of GATA-1 play essential roles in activin A-induced erythroid differentiation and apoptosis.

A novel therapeutic approach for hematological malignancies based on cellular differentiation and apoptosis.

Hematological malignancies including acute leukemia, and multiple myeloma are disorders characterized by the accumulation of neoplastic hematopoietic cells, resulting in aggressive clinical manifestations with poor prognosis. The therapeutic approach to these disorders is basically chemotherapy for achieving complete remission based on the concept of total cell kill. However, severe side effects and complications such as serious infection and bleeding due to anti-cancer drugs are major problems in the clinical setting. In addition, repeated episodes of relapse of the disease may lead to refractory or chemotherapy-resistant disorders. These problems are occurred because anti-cancer agents have effects on both cancer cells and normal hematopoietic cells. The clinical evidences thus suggest the limitations of the chemotherapy for hematological malignancies: novel effective therapeutic approaches with less toxicity are therefore actively being sought. Differentiation-inducing therapy employing a physiologically active derivative of vitamin A, all-trans retinoic acid (ATRA), brought remarkably advances in the therapeutic outcome of APL at the end of last century. More recently, the clinical success of imatinib mesylate (STI571), potent competitive inhibitor of the Bcr/Abl protein tyrosine kinase, in the treatment of CML has focused enthusiasm toward molecular targeted therapy for the hematological malignancies. The therapeutic activity of these agents can be explained by their abilities to modify cellular growth, differentiation, and apoptosis in cells by activating unknown gene programs that molecular cellular proliferation. We have actively sought out new agents among natural products and cytokines with the ability to induce cellular differentiation and apoptosis. In this symposium, I will present our recent data of these novel compounds and their molecular mechanisms for inducing differentiation and apoptosis of hematological malignant cells.

Elevated level of plasma basic fibroblast growth factor in multiple myeloma correlates with increased disease activity.

Recent reports that bone marrow angiogenesis is increased in multiple myeloma prompted us to examine plasma concentrations of angiogenic growth factors and to elucidate their clinical and biological significance. In 45 cases including 36 cases of multiple myeloma and 9 cases of monoclonal gammopathies of undetermined significance (MGUS), plasma concentrations of basic fibroblast growth factor (FGF-2) and vascular endothelial growth factor (VEGF) were evaluated. FGF-2 was significantly elevated in 25 out of 45 (56%) of the patients with multiple myeloma compared with control subjects (median 9.01 pg ml vs. 1.58 pg/ml, P < 0.0001). The 25 cases were all active multiple myeloma, and none of the non-active myeloma and MGUS patients showed a high FGF-2 level. VEGF level was also elevated in 26 out of 45 patients (58%) compared with control subjects (median 42.0 pg/ml vs. 15.8 pg/ml, P < 0.0001 for VEGF). VEGF concentration was high in 20 active myelomas, but also in one non-active myeloma and five MGUS. Elevation of FGF-2 level was associated with beta2-microglobulin level, anemia and bone marrow plasma cell percentage, which represent disease activity. Interestingly, none of five Bence-Jones type myelomas, including four clinically active cases, revealed a high plasma FGF-2 level, while all of them showed a high VEGF level. In all five responders, the plasma FGF-2 levels were significantly decreased after chemotherapy. FGF-2 was immunohistochemically detected in the bone marrow myeloma cells of the patients with high plasma FGF-2 level. We conclude that plasma concentration of FGF-2 can be a useful indicator of disease activity.

Bone morphogenetic protein (BMP)-2 induces apoptosis in human myeloma cells.

BMPs (bone morphogenetic proteins), members of the transforming growth factor (TGF)-beta superfamily, are a group of related proteins which are capable of inducing the formation of cartilage and bone, but are now regarded as multifunctional cytokines. However, little is known about their role in hematopoiesis. Recently, we found a novel function of BMPs to hematopoietic cells in that BMP-2 induces apoptosis not only in human myeloma cell lines, but also in primary samples from patients with multiple myeloma in vitro. BMP-2 caused cell cycle arrest in the G1 phase which was associated with accumulation of p21CIP1/WAF1 and p27KIP1, and the subsequent apoptosis of myeloma cells. Further analysis showed that BMP-2 induced down-regulation of Bcl-X(L) through the inactivation of STAT3, resulting in the induction of apoptosis in myeloma cells. We conclude that BMP-2 may have the potential to be one of the novel therapeutic agents for treatment in patients with multiple myeloma because of the beneficial effects on both myeloma cells and bone diseases. In this review, we summarize data concerning BMPs and BMP-2-induced apoptosis of myeloma cells including our own recent experimental data.

A metal chelator, diphenylthiocarbazone, induces apoptosis in acute promyelocytic leukemia (APL) cells mediated by a caspase-dependent pathway without a modulation of retinoic acid signaling pathways.

A metal chelator, diphenylthiocarbazone (dithizone), has been reported to induce differentiation and apoptosis of the human myeloid leukemia cell line HL-60, however, very little is known about the mechanism of dithizone-induced apoptosis. Here, we report for the first time that dithizone can induce inhibition of cellular growth of retinoic acid (RA)-sensitive NB4 and RA-resistant UF-1 APL cells via induction of apoptosis but not differentiation. Treatment of NB4 cells with dithizone markedly-induced apoptosis, which was associated with the loss of mitochondrial transmembrane potentials (Delta Psi(m)) and activation of caspase-3 and -9. Further investigation of the RA-resistant UF-1 APL cells showed that dithizone-induced apoptosis to a lesser extent. However, neither dithizone alone nor in combination with all-trans RA induced the expression of myeloid differentiation antigen CD11b. Concomitantly, the degradation of PML/RARalpha fusion protein was not observed after treatment with dithizone alone, and the degradation was not enhanced by the combination of dithizone and all-trans RA. We conclude that dithizone, a metal chelator, induced apoptosis without differentiation in APL cells in association with Delta Psi(m) collapse and caspase-3 and -9 activation.