LAMP3 inhibits cell growth and induces caspase-dependent apoptosis. (A) HSG and (B) A253 cells were transfected with 1.5 μg pME18S-empty or pME18S-LAMP3 plasmid, and then 2 × 105 cells of each cells were re-plated 24 h post-transfection. The number of cells was counted 96 h after re-plating with Countess Automated Cell Counter (N = 3 independent experiment and 2 technical replicates of each experiment). (C,D) HSG cells and (E,F) A253 cells were transfected with different concentrations of pME18S-LAMP3 plasmid or a pME18S-empty plasmid as control. Seventy-two hours post-transfection, apoptotic cells were counted by using flow cytometry with APC Annexin V/7-AAD. Difference from control cells is shown (N = 4). (G,H) Number of apoptotic cells in control and LAMP3-overexpressing (OE) HSG cell cultures 24, 48 and 72 h after transfection, assessed by flow cytometry using APC Annexin V/7-AAD. Difference from control cells is shown (N = 3). (I,J) Number of apoptotic cells in GFP+ control, LAMP3-OE and LAMP1-OE HSG cell cultures 48 h after transfection, assessed by flow cytometry using APC Annexin V/7-AAD. Difference from control cells is shown (N = 4). (K,L) Number of apoptotic cells in GFP+ control, LAMP3-OE and LAMP1-OE A253 cell cultures 48 h after transfection, assessed by flow cytometry using APC Annexin V/7-AAD. Difference from control cells is shown (N = 4). (M,N) Control and LAMP3-OE HSG cells were incubated with or without 20 μM Z-VAD-FMK (Z-VAD) for 20 h. Extent of apoptosis was determined by flow cytometry using APC Annexin V/7-AAD. Difference in rate of Annexin V+ cells in LAMP3-OE cell culture treated with or without 20 μM Z-VAD from that in control cell culture is shown (N = 4). *P < 0.05, **P < 0.01, ***P < 0.001, unpaired Student’s t-test. Values shown are mean ± SD.