Figure 4

Senescence and cell cycle proteins in GC tumors.

Robust Senescence-associated β-galactosidase (SA-β-Gal) accumulation was observed in GC tumors both in paraffin sections of whole mount SA-β-Gal-stained tumors (A) and in cryogenic sections stained for SA-β-Gal (B). SA-β-Gal accumulation was observed only in non-proliferative GC tumor cells (C). The boxed areas are shown in higher magnification in C’ and C”. Increased, nuclear accumulation of the DNA damage response protein γH2AX in GC tumors (D) compared to normal rat pituitary (E). Note that a few pituitary cells display cytoplasmic (likely unspecific) γH2AX signal. Confocal microscope analysis showing GH/γH2AX co-localization in GC tumor cells (F–H). (H) 3D reconstruction of the Z-stack for the pictures shown in (F,G). Increased accumulation of cyclin-dependent kinase inhibitor p21 in GC tumors (I) compared to normal rat pituitary (M). No expression of cyclin-dependent kinase inhibitor p27 is observed in GC tumors (K) but it is homogeneously expressed in normal rat pituitary (N). (L) Western blot analysis of p16 and p18 in 3 independent normal rat pituitary samples and 4 independent GC tumor samples. PTTG1 is overexpressed in GC tumors (O) compared to normal rat pituitary (P).