UCH-L1 supports cell survival in H838 cells Assessment of H838 and H157 cells exhibiting reduced UCH-L1 protein levels by phase-contrast microscopy revealed morphological changes in the UCH-L1 siRNA-treated H838 cells compared to scrambled siRNA- treated and untreated control cells, whereas no difference was observed between UCH-L1 siRNA-treated H157 cells

and control H157 cells. Normally the parental H838 cells were rounded in shape and uniform in size, but cells with reduced UCH-L1 expression were irregular in shape, variable in size, and present at a much lower density. H838 cells with low levels of UCH-L1 were also less flattened to the surface, possibly signifying they were becoming detached, a characteristic of apoptotic cells (Figure 4A). Therefore untreated and treated Torin 1 ic50 H838 cells were stained with H&E to compare the number of apoptotic cells. Definite apoptotic changes were observed in the UCH-L1 siRNA-treated cells (Figure 4B). To quantify the differences in apoptosis

between the siRNA-treated and untreated cells, Z-VAD-FMK price the number of apoptotic cells as characterised by fragmentation of the nucleus or breakdown of the nuclear envelope were counted in 20 fields of view at 250× magnification. A large increase in the number of apoptotic cells was observed in H838 cells with reduced UCH-L1 expression, which was statistically significant with a p-value of < 0.01 (Figure 4C). Figure 4 Reduced UCH-L1 expression alters morphology of H838

cells and increases the number of apoptotic cells. A. Phase-contrast microscopy photographs of i) non-transfected H838 cells; ii) scrambled siRNA-treated H838 cells; iii) UCH-L1 siRNA-treated H838 cells. B. H & E staining of i) non-transfected H838 cells; ii) scrambled siRNA-treated H838 cells; iii) UCH-L1 siRNA-treated H838 cells. (Scale bar is equivalent to 15 μm). C. Number of apoptotic cells counted in 20 fields of H&E stained slides at 250× magnification. Since apoptosis results in an increased number of cells in the sub G1/G0 phase of the cell cycle, flow cytometry was used to quantify this specific population of cells. H838 cells with reduced UCH-L1 were observed to have a greater proportion, around 30%, of cells in sub G1/G0 Tyrosine-protein kinase BLK phase which was statistically significant, and there was an overall decrease in the total cell population which correlates with an increased rate of apoptosis (Figure 5A & 5B). To further confirm apoptosis was present, PARP cleavage was measured by immunoblotting. Cleavage of the PARP protein into two fragments, an early indicator of apoptosis, was only apparent in H838 cells post UCH-L1 siRNA knock-down (Figure 5C). Studying cell proliferation using CyQUANT® assays at two different time points post-transfection indicated that loss of UCH-L1 expression did not affect cell proliferation (Additional File 1).