The least sensitive line was CD18 and the most responsive ones were CFPAC1 and MiaPaCa2. We saw no correlation between baseline telomerase activity and the response of the cell lines to GRN163L, as measured by their respective IC50. Figures 3B and 3C display the effects of long-term GRN163L exposure on the proliferation and lifespan of the two cell lines. In both lines, control populations treated with no drug or with the mismatched oligo grew at relatively constant rates throughout to produce curves that were almost identical. In their first 3�C8 weeks of growth, the 478-01-3 structure GRN163L-treated cells grew as fast as their corresponding control populations. But thereafter, proliferation of these cells declined progressively as they began to experience crisis. Crisis in these cultures was characterized by the appearance of senescent cells and by the ever increasing accumulation of floating cells, indicative of cell death. Eventually, weekly cell counts began to yield lower numbers of cells after growth than what had been plated a week prior, thereby giving rise to a stationary phase or plateau. Eventually, loss of the CAPAN1 and CD18 cells respectively occurred after a total of 47 and 69 doublings done in the presence of GRN163L. At the end of the growth curves, cells were examined for markers of senescence and apoptosis. The GRN163Ltreated populations contained adherent cells exhibiting the flat and enlarged phenotype associated with senescence. Staining for SA-b-galactosidase activity, a marker of senescence, confirmed that these enlarged cells were experiencing senescence. A significant fraction of cells expressing the activity was observed in the GRN163L-treated CAPAN1 and CD18 cells but not in control populations. At the end of the growth curves, cells were subjected to cell cycle analysis, using flow cytometry to 1282512-48-4 measure DNA content. Compared to their corresponding controls, the GRN163L-treated populations consistently exhibited a higher fraction of cells with an S or G2/M DNA content and lower percent of cells in the G1 phase. Also noted in the GRN163L-treated samples were large increases in cells containing a sub-G1 DNA content indicative of apoptosis
