Figure 2

Mahanine specifically down-regulates DNMT1 and DNMT3B. A. DNMT1, DNMT3A and DNMT3B cellular localization was visualized by immunofluorescent staining. PC3 cells were treated with DMSO (as control) or mahanine (10 μM) for 24 hours, following which they were fixed in methanol, incubated with the indicated antibodies, stained with Alexa Fluor 488-tagged secondary antibodies and counterstained with propidium iodide. Slides were then mounted and examined under a fluorescence microscope. The bright field images of PC3 cells treated with DMSO or mahanine (10 μM) for 24 hours are shown (right panel). B. Cytoplasmic and nuclear fractions were separated from PC3 cells treated with DMSO or 10 μM mahanine for 24 hours. The isolated fractions were subjected to Western blot analysis to assess DNMT expression. The fold change in the expression of the respective DNMTs as compared to the control is indicated at the bottom of each immunoblot. Nucleolin and β-actin were used as loading controls for the nuclear and cytoplasmic fractions, respectively. C. PC3 and LNCaP cells were treated as indicated with DMSO or mahanine following which cells were lysed and the extracts were subjected to Western blot analysis to detect DNMT1, DNMT3B and DNMT3A protein levels (left). Quantitative estimations of the relative levels of DNMT1, DNMT3A and DNMT3B proteins were determined by densitometric measurements of immunoblots from three independent experiments after normalization with β-actin (right). Columns, mean; bars, SEM. *p < 0.05, significantly different from control. D. PC3 and LNCaP cells were treated with DMSO or 10 and 20 μM mahanine, respectively for 24 hours. Subsequently, cells were harvested for RT-PCR analysis to measure DNMT1 and DNMT3B expression. GAPDH was used as an internal control.