Figure 7. Loss of WRN function in MSI-H CRC causes severe chromosomal defects.

(A) MSS and MSI-H CRC cell lines were transfected with the indicated siRNAs. Mitotic chromosome spreads were prepared 72 hr after transfection and visualized by microscopy. Non-homologous radial formations are designated by arrows, breaks are labeled with asterisks. (B) Quantification of chromosomal defects observed in siRNA knock-down studies in MSS and MSI-H CRC lines and hTERT RPE-1 non-transformed cells. The status of chromosomal breaks of individual metaphase spreads was categorized into normal, 1–5 breaks or more than five breaks (n ≥ 28 spreads of two independently analyzed slides). Non-homologous radial formation was counted as two breaks.

Figure 7—figure supplement 1. Elevated levels of the DNA damage marker γ-H2AX upon loss of WRN function in MSI-H CRC cells.

(A) MSS and MSI-H CRC cell lines were transfected with the indicated siRNAs or treated with 5 µM etoposide. Immunofluorescence analysis was performed 72 hr after transfection or 24 hr post etoposide treatment. (B) Quantitative analysis of γ-H2AX mean nuclear intensities upon siRNA-mediated knock-down of WRN or etoposide treatment in MSS and MSI-H CRC lines and hTERT RPE-1 non-transformed cells. Data information: In (B), individual values and mean of two independent experiments (n ≥ 140 cells) are presented.