Objective To assess the effect and underlying molecular events of caffeic acid phenethyl ester (CAPE) on rat hepatic stellate HSC - T6 cells. Methods HSC - T6 cells were grown and treated with different concentrations of CAPE (5, 10, or 15 µ,moVL), transfected with or without LC3 - GFP plasmid, and then treated with or without an autophagy inducer rapamycin or the autophagy inhibitor 3 - methyladenine (3 - MA). The changed cell viability and morphology were assessed by using cell viability MTT assay and Transmission electron microscope, respectively. The expression of LC3 protein in HSC - T6 cells was detected by immunofluorescence assay, the autophagy - related genes expression of ATG5, ATG7, ATG12, Beclinl and LC3 were detected by qRT - PCR, and the expression of ATG7, Beclinl, LC3 I/ II, p - AKT/ AKT, p - mTOR protein was detected by Western - blot. Comparison between multiple groups was analyzed by one - way ANOV A with Dunnett t - test. Results Compared with the control, CAPE treatment significantly reduced cell viability but induced formation of lipid droplets and roulette - shaped autophagosomes. Compared with the control (13. 34% ±2. 59), LC3 protein was significantly induced in HSC -T6 cells after CAPE treatment (5 µ,mol/L, 23 . 68% ± 3. 76, t = - 5. 553, P < 0 . 001; 10 µ,mol/L, 43. 47% ± 3 . 83, t = - 15. 958, P <0. 001; 15 µ,M, 57. 25% ±2. 78, t = - 28. 334, P < 0. 001), while levels of ATG5, ATG7, ATG12, Beclin 1, and LC3 mRNAs were all significantly increased in 10 µ,m and 15 µ,m CAPE treated cells vs the control (all P < 0. 05). After LC3 overexpression in HSC - T6 cells, LC3 protein was induced vs the vector control (79. 01 % ± 6. 69% vs 67. 06% ± 6. 74%, t = - 3. 083, P = 0. 012), while rapamycin treatment further increased LC3 expression (86. 88 % ± 5. 42%, t = - 2. 23 9, P = 0 . 049); however, 3 - MA treatment significantly decreased LC3 expression in cells (71. 22 % ± 4. 29%, t = - 2. 404, P = 0. 037). In addition, levels of ATG7, Beclinl, and LC3 I I JI proteins were increased, whereas levels of AKT/p - AKT and p - mTOR were decreased in the CAPE and rapamycin groups vs controls. However, the 3 - MA treatment had an opposite result, indicating that 3 - MA reversed CAPE - induced effects in HSC - T6 cells. Conclusion Caffeic acid phenethyl ester may induce autophagy to reduce cell viability in hepatic stellate cells by inhibition of the AKI/ mTOR signaling. [ABSTRACT FROM AUTHOR]