Figure 3. mTOR inhibition reduces the self-renewal of cancer stem-like cells in PANC-1 cells.

(a) Rapamycin reduced the viability of PANC-1 cells in the two-dimensional culture. PANC-1 cells were treated with the indicated concentrations of rapamycin for three days. Cell viability was determined as indicated in Figure 1(a). Representative photographs of spheres (primary spheres) cultured in the stem cell medium in the absence (b) or presence of 10 nM (c) and 100 nM (d) rapamycin. Scale bar: 200 μm. (e) Rapamycin does not affect the number of primary spheres. The cells were cultured and assayed, as described in Figure 2(e). (f) Rapamycin reduces the size of primary spheres. The cells were cultured as in (e), and the results are indicated in Figure 3(f). (g) and (h) Representative photographs of secondary spheres. Single cells from primary spheres that were untreated (g) or treated with 100 nM rapamycin (h) were plated in 96 wells and then cultured without rapamycin for eight days. Scale bar: 200 μm. (i) Rapamycin reduces the self-renewal capacity of stem-like cells, as reflected by the formation of secondary spheres. Single cells from primary spheres were seeded in 96-well plates and cultured without rapamycin for eight days. The indicated results are the mean values and s.d. of the number of secondary spheres formed per 96-well plate. All data are the mean ± s.d. *P < 0.01.