Fig. 2

Centriole amplification is widespread in cancer cells. a Immunofluorescence images of cell lines without (upper panel) and with (lower panel) centriole amplification. Cells were stained with DAPI (blue), centrin (green), α-tubulin (red) and CP110 antibodies (red-insets). Scale bar 5 µm, insets 1 µm. Note the presence of centrin dots lacking CP110 staining in the SN12C cell line (upper panel-inset 1). b Output of the secondary immunofluorescence screenings for centriole number in the NCI-60 panel. To validate the primary screening, the top 50% of amplification and a subset of less-defective ones from the primary screening were incorporated in the secondary screening (see text). The results of the secondary screening are depicted in the bar graph in which cell lines were ranked according to their percentage of mitotic cells with more than four centrioles. To define the cut-off for centriole amplification and the variability of centriole number in non-cancerous cell lines, we quantified centriole number in five non-cancerous cell lines (depicted in green): RPE-1 (retinal pigmented epithelial cells), HB2 (mammary luminal epithelial cells), HaCat (keratinocytes), LT97 (colon adenoma cells) and SAEC (small airway epithelial cells). The average percentage of cells with centriole amplification in the non-cancerous cell lines is 7 ± 3%, therefore we set the cut-off for centriole amplification to 13% (average + 2 standard deviations). 28 cell lines from the NCI-60 panel displayed significant centriole amplification. Note that for most of the cell lines, the majority of cells with amplification showed 5 to 8 centrioles per cell (grey). Cells with more than eight centrioles per cell (red) were less commonly observed. A total of 50 to 60 mitotic cells were analysed per cell line. BR breast, CNS central nervous system, CO colon, BL blood, LU lung, PR prostate, KI kidney, OV ovaries and SK skin. c TEM images of control (RPE-1) and SN12C cells with normal number of centrioles (2), and a MDA-MB-435 cell with supernumerary centrioles (8). Each TEM picture represents an individual cell for the control and SN12C cell lines, whereas the remaining pictures are serial sections of the same MDA-MB-435 cell. Scale bar 500 nm