AIM:Pancreatic cancer in the head is frequently accompaniedby jaundice and high bile acid level in serum.This studyfocused on the direct effects of bile acids on proliferationand ultrastructural alteration of pancreatic cancer.METHODS:Pancreatic cancer cell lines PANC-1,MIA PaCa-2 and PGHAM-1 were explored in this study.The cell lineswere cultured in media supplemented with certain bile acids,CA,DCA,LCA,TCDC,TDCA and GCA.Their influence oncell growth was measured with MTT assay after 72 h ofincubation.Cell cycles of PANC-1 cells in 40 μM of bile acidsmedia were analyzed by flow cytometry.Ultrastructuralalteration of PANC-1 cells induced by DCA was observedusing scanning and transmission electron microscope(SEMand TEM).RESULTS:At various concentrations of bile acids andincubation time,no enhanced effects of bile acids on cellproliferation were observed.Significant inhibitory effectswere obtained in almost all media with bile acids.DCA andCA increased the percentage of G_0+G_1 phase cells,whileGCA and TDCA elevated the S phase cell number.After 48 hof incubation in DCA medium,PANC-1 cells showed somestructural damages such as loss of their microvilli andvacuolization of organelles in cytoplasm.CONCLUSION: Bile acids can reduce proliferation ofpancreatic cancer cells due to their direct cytotoxicity.Yhis result implies that elevation of bile acids in jaundiced serummay inhibit pancreatic cancer progression. AIM: Pancreatic cancer in the head is frequently accompanied by jaundice and high bile acid level in serum. This study has documented the direct effects of bile acids on proliferation and ultrastructural alteration of pancreatic cancer. METHODS: Pancreatic cancer cell lines PANC-1, MIA PaCa-2 and PGHAM-1 were explored in this study. The cell lines were cultured in media supplemented with certain bile acids, CA, DCA, LCA, TCDC, TDCA and GCA.Their influence oncell growth was measured with MTT assay after 72 h ofincubation. Cell cycles of PANC-1 cells in 40 μM of bile acidsmedia were analyzed by flow cytometry. Ultrastructuralalteration of PANC-1 cells induced by DCA was observed using scanning and transmission electron microscope (SEM and TEM) .RESULTS: At various concentrations of bile acids andincubation time, no enhanced effects of bile acids on cell proliferation were observed. Significant inhibitory effectswere obtained in almost all media with bile acids. DCA andCA increased the percentage of G_0 + G_1phase cel ls, whileGCA and TDCA elevated the S phase cell number. After 48 h of incubation in DCA medium, PANC-1 cells showed somestructural damages such as loss of their microvilli and vacuolization of organelles in cytoplasm. CONCLUSION: Bile acids can reduce proliferation of pancreatic cancer cells due to their direct cytotoxicity. This result implies that elevation of bile acids in jaundiced serummay inhibit pancreatic cancer progression.