Fig. 6

Inactivation of autophagy or Notch signaling reduces serotonin mediated cell survival while increasing serotonin induced drug resistance in HepG2 and SK-Hep1 cells. a HepG2 and SK-Hep1 cells were grown in 96 well plates treated with serotonin (0.5 mM), 3-MA (4 mM), serotonin plus 3-MA, avagacestat (2 μM), serotonin plus avagacestat, FLI-06 (1 μM), and serotonin plus FLI-06 as indicated for 48 h. b Similarly, HepG2 and SK-Hep1 cells were grown in 96-well plates and treated with serotonin (0.5 mM), sorafenib (2.5 μM), serotonin plus sorafenib, regorafenib (0.5 μM), and regorafenib plus serotonin as indicated for 48 h. Cells were treated with 5 μl MTT reagent/well (5 mg/ml in PBS) and cell survival was measured by reading the plate at 570 nm using a Fluostar Omega plate reader. Each combination of the cell line and drug concentration was set up in triplicate. Data are expressed as the mean ± S.D. * p < 0.1, **p < 0.01 compared to control. ^ββP < 0.01 compared to 3-MA. ^### p < 0.001 compared to sorafenib treatment. ^†††p < 0.001 compared to regorafenib treatment. Serot.-Serotonin. AVG- Avagacestat. 3-MA- 3-Methyladenine. OA- Oleic acid