Figure 2

PI3K activity in bile acid-treated McNtcp.24 cells. (A) Cells were treated with 100 μM bile acid for 1 h and then PI3K activity in crude membrane fractions were assayed as described in the Materials and Methods. Both TCA and TCDCA stimulated PI3K activity. (B) Activation of caspase 8 in bile acid-treated McNtcp.24 after pretreatment with 20 μM LY294002. McNtcp.24 cells were treated with LY294002, a PI3K inhibitor, for 30 min before incubation with 100 μM TCA or TCDCA for 2 h. Note the loss of tolerance of McNtcp.24 cells to taurine-conjugated bile acids as reflected by the activation of caspase 8 activity (middle and right bars). (C) McNtcp.24 cells were incubated with TCA or TCDCA for 30 min before incubation with 50 μM GCDCA for 1 h. Note the attenuation of caspase 8 stimulation when McNtcp.24 cells were exposed to taurine-conjugated bile acids prior to GCDCA treatment (fourth and last bars). The values shown are means ± SD (n = 3). Differences in comparison to controls (no addition in (A), (B); GCDC-treated cells in (C)) were evaluated using Student's t-test. ^*P < 0.05; ^**P < 0.001. The experiments in (A), (B), and (C) were repeated three times with similar results.