Monensin-mediated growth inhibition in acute myelogenous leukemia cells via cell cycle arrest and apoptosis.

Monensin, an Na(+) ionophore, regulates many cellular functions including apoptosis. However, there has been no report about the antitumoral effect of monensin on acute myelogenous leukemia (AML). Here, we investigated the antiproliferative effect of monensin on AML cells in vitro and in vivo. Monensin efficiently inhibited the proliferation of all of 10 AML cell lines, with IC(50) of about 0.5 microM. DNA flow cytometric analysis indicated that monensin induced a G(1) and/or a G(2)-M phase arrest in these cell lines. To address the mechanism of the antiproliferative effect of monensin, we examined the effect of monensin on cell cycle-related proteins in HL-60 cells. The levels of CDK6, cyclin D1 and cyclin A were decreased. In addition, monensin not only increased the p27 level but also enhanced its binding with CDK2. Furthermore, the activities of CDK2- and CDK6-associated kinases reduced by monensin were associated with hypophosphorylation of Rb protein. Monensin also induced apoptosis in AML cells including HL-60 cells. The apoptotic process of HL-60 cells was associated with changes in Bax, caspase-3, caspase-8 and mitochondria transmembrane potential (Deltapsi(m)). In particular, monensin (i.p. at a dose of 8 mg/kg thrice weekly) significantly reduced the tumor size of BALB/c mice that were inoculated s.c. with its derived cell line, WEHI-3BD cells (69% growth inhibition relative to control group; p < 0.05). Tumors from monensin-treated mice exhibited increased apoptosis, and these tumor were immunohistochemically more stained with Bax, Fas and p53 antibodies than control tumors. In conclusion, this is the first report that monensin potently inhibits the proliferation of AML cells.

Phase II study of docetaxel and cisplatin combination chemotherapy in metastatic or unresectable localized non-small-cell lung cancer.

BACKGROUND: Docetaxel is highly active in the second-line treatment of patients with metastatic or unresectable locally advanced nonsmall-cell lung cancer (NSCLC). As there is a need for first-line chemotherapy that is more effective than standard platinum-based chemotherapy, this study was undertaken to evaluate the efficacy and tolerability of a docetaxel/cisplatin combination as first-line chemotherapy in advanced NSCLC. METHODS: Newly diagnosed, chemotherapy-naive patients with histologically confirmed NSCLC (measurable stage IIIB/IV NSCLC; Karnofsky performance status, 70-100; adequate bone marrow, renal, hepatic, and cardiac function) were eligible for the study. Docetaxel 75 mg/m2 was administered IV over 1 h, followed immediately by cisplatin 75 mg/m2, given IV over 30 min, with cycles repeated every 3 weeks, for up to six or nine cycles. RESULTS: Thirty-nine patients were enrolled and treated. Their median age was 59 years (range, 32-71 years) and median performance status, 90 (range, 70-100). Histologically, 23 patients (59%) had adenocarcinoma, 12 (30.8%) had squamous cell carcinoma, and 16 patients (41%) had stage IV disease. Thirty-seven patients were eligible for inclusion. In the 39 patients evaluable for safety, significant grade 3/4 toxicities included neutropenia (82%), nausea (10.3%), fatigue (10.3%), and diarrhea (7.7%). Of the 33 patients evaluable for response, 16 patients (48.5%) achieved a partial response and 7 showed progressive disease. Median overall survival time in all eligible patients was 10.5 months. CONCLUSION: Docetaxel/cisplatin produced promising response rates that compare favorably with those of current standard platinum combinations, with manageable toxicity. Further investigations of this first-line combination in NSCLC are warranted.