Fig. 1

Serotonin promotes cell survival and cell steatosis in liver cancer cells HepG2 and SK-Hep1. a Upper Panel: HepG2 and SK-Hep1 cells were grown in 96 well plates and treated with indicated concentrations (0.1–0.5 mM) of serotonin for 48 h and cell proliferation was measured using WST1 assay as described in the materials and methods section. Lower Panel: HepG2 and SK-Hep1 cells were grown in 96 well plates treated with indicated concentrations of serotonin for 48 h. Cell survival was measured using MTT assay on Fluostar Omega plate reader as described in materials and methods section. b Oil-Red-O-stained lipid droplets present in HepG2 and Sk-Hep1 cells treated with different concentrations of serotonin (0.5 mM and 1 mM) were measured from the cells (n = 10) and plotted (upper and lower panels). c Oil Red O staining and representative images observed under a light microscope after oleic acid and serotonin treatment (upper panel). After Oil Red O staining, cells were lysed and Oil Red O stain released from steatotic cells was then transferred to another 96-well plate and the absorbance at 405 nm was measured as described previously [19] (lower panel). d HepG2 and SK-Hep1 cells were treated with indicated concentrations of serotonin for 24 h and 50 μg cell lysates were immunoblotted with indicated lipid metabolic proteins antibodies as described in the materials and methods section. 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, *** p < 0.001 compared to control/OA. Serot. - Serotonin. OA- Oleic acid