Figure 3.

MAOA inhibition has limited sensitizing effect on chemo or radiation treatment. (A) Expression of MAOA mRNA in a panel of 6 PDAC cell lines and MAOA protein in HPAF-II and MiaPaCa-2 cells. (B) MAOA activity in HPAF-II and MiaPaCa-2 after treatment with 1 μM MAOA inhibitor clorgyline. Cell lysates were incubated with clorgyline for 1 hour in the dark at 37°C followed by fluorometric measurement of enzymatic activity at 37°C. (C) Schematics representation of the study design followed in these inhibitor sensitization experiments. (D) Inhibition of MAOA for 48 hours using clorgyline (EC₂₀ values) followed by gemcitabine (1 μM), radiation (10 Gy), and chemoradiation for a further 72 hours reduced cell viability in HPAF-II cells. Cell viability was confirmed using MTT assay. (E) Inhibition of MAOA has no effect on cell death in HPAF-II cells. Cell death was confirmed using annexin V/PI staining. Data represents mean ± SD of three independent experiments. Statistical significance was determined using a two-sided Student t test with P < .01 (**) and P < .001 (***) against cells treated with gemcitabine, radiation or chemoradiation only. (F) Increased expression MAOA mRNA following radiation of HPAF-II and MiaPaCa-2 cells.