Alterations in the mitotic spindle checkpoint in H/RS cells. (A) Analysis of centrosomes in tissue sections from HL tumors. Immunofluorescence staining for pericentrin-2 (red) and CD30 (green) revealed structural and numeric aberrations in H/RS cells. Images were obtained with a TCS-SP2-AOBS-UV confocal microscope equipped with a PL-APO 100 ×/1.40-0.70 oil-immersion objective lens and LCS software (Leica Microsystems, Bannockburn, IL). (B) Cell-cycle profiles of HL-derived cell lines and lymphoblastoid B cells (PBL-B) treated with nocodazole. (C) Quantification of the percentage of apoptotic and hyper-G2/M cells in panel B. Lymphoblastoid cells displayed a normal response to nocodazole (mitotic arrest preceding massive apoptosis), whereas HL-derived cell lines had a lower apoptotic index and higher hyper-G2/M fraction at late time points. (D) Mitotic index after nocodazole treatment. HL-derived cell lines arrest in mitosis less efficiently than lymphoblastoid cells, indicating an impaired mitotic checkpoint.
