Effects of glucocorticoids on the growth and chemosensitivity of carcinoma cells are heterogeneous and require high concentration of functional glucocorticoid receptors

Figure 1 Effect of DEX on the growth and chemosensitivity in carcinoma cell lines. Cell numbers were measured by MTT assay and were plotted as a percentage of the control (cells not exposed to drugs); A: Growth of MCF-7, MCF-7/MXR1, MCF-7/TPT300, and HeLa cells were suppressed by DEX. Data of AGS represent the other 10 cell lines, growth of which was not affected by DEX; B: SiHa cells pretreated with DEX for 3 h were more sensitive to cisplatin; C and D: Pretreatment with DEX 1 mmol/L for 24 h diminished cisplatin cytotoxicity in H460 cells and Hep3B cells; E: Data of AGS represent the seven cell lines (AGS, N87, Caski, Hut 7, SNU1, NPC-TW01, and NPC-TW04), of which cytotoxicity of cisplatin was not affected by DEX. All values represent mean±SD of six separate wells.

Figure 2 Functional assay of the GR in NPC-TW01 and NPC-TW04 cells. NPC-TW01, NPC-TW04, and MCF-7 cells were transiently transfected with MMTV reporter plasmid (lanes M and M+DEX) or co-transfected with MMTV reporter plasmid and pS-hGR (lane M/G+DEX). The cells were then treated with 1 μmol/L DEX for 6 h (lanes M+DEX and M/G+DEX). Then the luciferase activity was assayed and represented in terms of folds of the induction activity of the control (lane M). All values represent mean±SD of three experiments(A,B).

Figure 3 Increased drug resistance to cisplatin in pS-hGR-transfected AGS. AGS cells were transfected with pS-hGR and MTT assay were performed. A: GR number measured by [³H]-labeled ligand binding assay. Pool: AGS/GR-pool; AGS cells transfected with pS-hGR, pooled cells. c1: AGS/GR-c1; AGS cells transfected with pS-hGR, single cell cloned, clone 1. c2: AGS/GR-c2; AGS cells transfected with pS-hGR, single cell cloned, clone 2. Mock: AGS/empty vector; AGS cells transfected with empty vector. c3: AGS/GR-c3; AGS cells transfected with pS-hGR, single cell cloned, clone 3; B-D: Pretreatment with DEX 1 μmol/L for 3 h diminished cisplatin cytotoxicity in AGS/GR-pool, AGS/GR-c1, and AGS/GR-c2 cells; E and F: Pretreatment with DEX 1 μmol/L for 3 h had no effect on the cisplatin cytotoxicity in AGS/empty vector cells and AGS/GR-c3. All values represent mean±SD of six separate wells.

Figure 4 A: Immunocytochemical stain for GR expression in representing carcinoma cell lines. (A¹) and A²): SiHa cells, which had GR content about 8.1×10⁴/cell according to ligand binding assay; (A³) and (A⁴): HeLa cells, with GR content about 1.97×10⁴/cell; (A⁵) and (A⁶): N87 cells, with GR content about 5.0×103/cell. (A²), (A⁴), and (A⁵): cells treated with DEX for 3 h before harvest. In (A¹) and (A³), the GR immunoreactivity localized in cytoplasm. After DEX treatment, the immunoreactive GR translocalized to nuclei (A²) and (A⁴). The low GR content cancer cells N87 showed negligible immunoreactivity. B: Immunohistochemical stain for GR expression in human carcinoma tumor tissue samples. Non-small cell lung cancer tumor samples, with high GR expression (B^a), and low GR expression (B²). Breast cancer tumor samples, with high GR expression (B³), and low GR expression (B⁴).