Tyrosine kinase inhibitor SU11274 increased tumorigenicity and enriched for melanoma-initiating cells by bioenergetic modulation

Table 1 Frequency of tumor initiating cells

Confidence intervals for 1/(stem cell frequency)
Rel3	Lower	Estimate	Upper
Spheroid cells	84,848	33,233	13,016
SU11274-treated spheroid cells	7208	3289	1501
M14	Lower	Estimate	Upper
Spheroid cells	168,352	38,964	9018
SU11274-treated spheroid cells	29,964	10,211	3479

Human melanoma cells were cultured in non-adherent conditions for 7 days in the presence or absence of 1 μM SU11274. Cells were counted, diluted in 1:1 serum-free medium: ECM gel and injected s.c. (n = 4/each group). Following numbers were injected: 50,000; 10,000; 5000; 1000; 500; 100; 50 and 10 Rel3 cells, and 20,000; 2000; 200 and 20 M14 cells based on preliminary test of tumorigenicity. Stem cell frequency was calculated by ELDA analysis, p value was ≤ 10⁻⁵ for the Rel3 cells, and ≤ 0.05 for the M14 cells. The tumor take rate was significantly higher in the SU11274-treated cells: 3 out of 4 inoculations of 500 SU11274-treated EGFP-A375/Rel3 cells gave tumors in contrast to 0 out of 4 inoculations of the untreated cells. Similarly, 4 out of 4 inoculations of 2000 SU11274-treated M14 cells gave tumors in contrast to 0 out of 4 inoculations of the untreated M14 cells

ISSN: 1471-2407