Figure 2

NaK alpha1-subunit and in vitro growth inhibition of cancer cells. A: Correlation of Ki for inhibition of human α1β1 by cardiac glycosides and the growth inhibition effects (IC₅₀) of human cancer cells; 1: digoxin; 2: hellebrin; 3: ouabain; 4: oleandrin; 5: hellebrigenin; 6: gamabufotalin-rhamnoside. IC₅₀ values are the averages ± SEM of 4 experiments with 10 different human cancer cell lines from the NCI60 library: ACHN (renal cell carcinoma); SF-268 and SNB-75 (glioma); MCF-7 (breast cancer); SKMEL-5 (melanoma); HCT-116 and HT-29 (colon cancer); A549 (NSCLC); TK-10 (kidney cancer); and Ovcar-3 and Ovcar-4 (ovarian cancer). In this experiment, the IC₅₀ values were determined after two days of culture using the crystal violet assay [54]. B: Illustration of the IC₅₀in vitro growth inhibitory concentration (MTT colorimetric assay; Y axis) as opposed to the mRNA levels (by means of quantitative RT-PCR as detailed in [10]) of the NaK α1 subunit in five human cancer cell lines, including Hs683 oligodendroglioma (207 mRNA copies / μg cDNA); T98G GBM (911 mRNA copies / μg cDNA); A549 NSCLC (1,450 mRNA copies / μg cDNA); U373 GBM (2,091 mRNA copies / μg cDNA); and PC-3 prostate adenocarcinoma (5,337 mRNA copies / μg cDNA) cells. The IC₅₀ growth inhibitory concentrations that are reported in Figure 2B are from Table 1.