Antitumor Effects of JBD57 in Human Multiple Myeloma Cells in Vitro

JBD57 is a nucleoside/nucleotide analogue that in human cells causes depletion of mitochondrial DNA by disrupting oxidative phosphorylation pathways leading to toxic accumulation of nonesterified fatty acids, dicarboxylic acids and free radicals. Human 26S proteasome is also a target for JBD57. Here we evaluated JBD57 citotoxicity in several human tumor cell lines in vitro. Human MM cell line RPMI 8226/S (CCL-155), human T-cell lymphoblastic-like (Jurkat) and human T-cell leukemia (1301) were grown in RPMI 1640 medium; uterine sarcoma (MES-S (CRL-1976) cells were grown in McCoy medium; HUV-EC-C (CRL-1730) cells were grown in 199/EBSS medium. Media were supplemented with 10 % FBS. Cells were incubated at 37°C in a water-jacketed incubator with 5 % CO2. To evaluate JBD57 citotoxicity in RPMI 8226/S, MES-S, Jurkat, 1301 and HUV-EC-C cells, 104cells/well were grown in flat-bottomed 96-well tissue culture plates for 24, 48 and 72 hr; JBD57 was added to the media in several concentrations (0μM, 32.25μM, 62.5μM, 125μM, 250μM and 500μM). At the end of the experimental periods, cell viability was determined by the MTT method. JBD57 inhibited the growth of MM cell line RPMI 8226/S in a dose- and time-dependent manner. Cell viability decreased progressively with increasing concentrations of JBD57 as well as with increasing time periods. The IC50 (inhibitory concentration at 50%) was 125 μM at 72 hr. The viability of the MM cells after 72 hr incubation with JBD57 500μM was 33%, whereas 100% viability was observed when no drug was added. On the other hand, JBD57 did not affect cell viability of any of the other studied cell lines (uterine sarcoma, Jurkat, 1301 and HUVEC-C). JBD57 promotes a significant human MM cell death in a dose and time dependent manner but do not affect neither normal cell HUV-EC-C nor the tumoral cells MES-S, Jurkat and 1301, at least in the studied conditions. These results suggest that the potent antitumoral activity of JBD57 observed against MM cells could be potentially useful in the treatment of multiple myeloma.