Figure 6.

Jasplakinolide does not incur cytotoxicity or apoptosis by 6 hrs. (A) MCF-10A, SkBr3, and MDA-436 populations were assayed by colorimetric detection of XTT tetrazolium reduction for alterations in viability after 6 hrs of incubation with 500nM jas. Each of the cell lines tested were viable at the experimental concentration of 500nM, remaining above a value of 1.00, relative to 0.15% DMSO control treated cells. This trend was observed for concentrations up to 10μM (inset, blue line denotes relative viability of 1.00). Bars represent mean + S.E.M for samples from three independent trials.. (B) Individual cells were tested for their ability to exclude propidium iodide (PI). Arrows specify McTN protrusions visible via fluorescent labeling with wheat germ agglutinin (WGA) (top row). PI stained nuclei of cells with compromised membrane integrity, indicated by arrowheads (bottom row). (C) Western blot analysis reveals no significant cleavage of ADP-ribose polymerase (ΔPARP) by 3 hrs in MCF-10As, and by 6 hrs of 500nM jas exposure in the tumor lines examined. TRAIL positively induced PARP cleavage (far right lane). SkBr3 cells exhibit decreased levels of β-actin at each time-point, and MCF-10As appear to upregulate β-actin over the experimental time course, while expression levels were unaltered in MDA-436s. α-tubulin levels indicate even loading of protein samples.