Figure 1
From: In vitro evidence for senescent multinucleated melanocytes as a source for tumor-initiating cells
Nevus melanocytes and senescent melanocytes are frequently multinucleated. (a) Left: Acquired cutaneous nevus, stained with periodic acid Schiff (PAS) reagent to visualize the membranes. PAS was used for the detection of mucosubstances including glykoproteins and glykolipids that are characteristic for cellular membranes. The dense, dark stained lines between the cells demarcate the membranes. Right: Magnification of the highlighted region. Some of the multinucleated cells are marked by white circles. White scale bar: 25 μm, black scale bar: 5 μm. (b and c) Expression of N-RAS61K using the plasmid pCDH-CMV-N-RAS61K-EF1-copGFP, inducing flat and binuclear appearance shortly after introduction of the plasmid. The arrows in (b and c) indicate two different nuclei in single cells. (d and e) After 3 weeks of cultivation, GFP/N-RAS61K-positive cells started to form colonies, which overgrew the cell culture. (f) In addition, detached cell clusters were found in the supernatant. The unfocused cells in the background represent the attached, non-transfected cells at the bottom of the culture dish. (g) The detached cell clusters could be replated, demonstrating anoikis resistance. Scale bars, 100 μm. Similar observations were made in three independent experiments. (h) RT-PCR analysis (28 cycles) of TYRP1 and DCT expression in NHEM control cells and two N-RAS61K-transgenic NHEM cell clones, which grew out after several weeks of cultivation and developed anoikis resistance. The RT-PCR is representative of three independent biological replicates. Ribosomal S14 was used as a reference
