DIFFERENCES IN SPATIAL LOCALIZATION AND CHROMATIN PATTERN DURING DIFFERENT PHASES OF CELL-CYCLE BETWEEN NORMAL AND CANCER-CELLS

We studied differences in chromatin patterns and the spatial localizat ion of centromeres of chromosome 11 during the cell cycle between norm al peripheral blood lymphocytes (PBL) and human promyelocytic leukemia cells (HL-60) using fluorescence in situ hybridization. The pericentr omeres in both cells were located at the periphery during Gq (quiescen t) phase, but moved towards the nuclear center in G1 and mid-S phase. During G2, the pericentromeres of PBL continued to move towards the nu clear center whereas those of HL-60 returned to the periphery. The ang le defining the spatial location of two pericentromeres, in reference to the center of the nucleus, increased in PBL cells from a mean of 67 degrees during Gq phase to 106 degrees during G1 phase (P < 0.01), an d the two pericentromeres remained wide apart throughout the entire ce ll cycle. In HL-60, the angle also increased during G1, but then decre ased during mid-S and G2 phases. Both cells exhibited pericentromeric signals during Gq that were round and compact, and the entire chromati n was loosely condensed The signal became more loose and dispersed dur ing the G1 and mid-S phases. The pericentromere signal varied during G 2 and was generally rod-like or bipartite with condensation of the ent ire chromatin or chromosome-like. Our results suggest that subtle but important differences in spatial localization of pericentromeres are p resent during the interphase between normal PBL and HL-60 cells. Cytom etry 27:327-335, 1997. (C) 1997 Wiley-Liss, lnc.