Figure 3

Phosphorylated iASPP accumulates in the nucleus of prostate cancer cells. (a) Highly metastatic LNCaP-LN3 prostate cancer cells expressed predominantly nuclear iASPP, whereas LNCaP cells with lower metastatic potential expressed iASPP with a relatively equal distribution between nucleus and cytoplasm. The p53-null PC3 cell line and p53-mutant (P233L and V274F) DU145 cell line expressed predominantly cytoplasmic iASPP. (b) iASPP migrated as two bands in an immunoblot of whole-cell protein extracts from prostate cancer cells. LNCaP-LN3 cells predominantly expressed the slower migrating iASPP band previously identified as being nuclear localised phosphorylated iASPP. LNCaP cells expressed both slow- and fast-migrating iASPP, corresponding with its roughly equal subcellular distribution. PC3 and DU145 cells, which exhibited predominantly cytoplasmic localised iASPP, expressed predominantly fast-migrating unmodified cytoplasmic iASPP. (c) The slower migrating modified iASPP band is primarily detected in nuclear protein extracts, whereas the faster migrating unmodified iASPP band is localised primarily to the cytoplasm. Invasive metastatic LNCaP-LN3 cells express a greater proportion of modified nuclear iASPP than non-invasive LNCaP cells