LOCALIZATION OF ANTI-CENP ANTIBODIES AND ALPHOID SEQUENCES IN ACENTRIC HETEROCHROMATIN IN A BREAST-CANCER CELL-LINE

Karyotype alterations are a hallmark of cancer cells. Of particular in terest to our laboratory are the inactive centromeres and blocks of he terochromatin devoid of the accompanying centromere. When purified or monospecies anticentromere proteins (CENP) antibodies or the whole ser um from scleroderma (crest) patients are applied to human chromosomes, the centromere region exhibits the label. When we treated MDA 435 cel ls with the anti-CENP-A, anti-CENP-B, or the whole serum, the label wa s apparent on heterochromatin pericentric to the active and inactive c entromeres. Moreover, blocks of heterochromatin not associated with an y centromere also exhibited the label. Anti-CENP-C, however, is more s trictly confined to the centromere in discrete dots and is not detecte d on any region except the sites of active centromeres. Distribution o f alpha sequences also shows a pattern compatible with its distributio n in the heterochromatin. Apparently the use of anti-CENP-A and anti-C ENP-B antibodies or alphoid DNA may not defect either the centromere ( primary constriction) or the kinetochore; CENP-C may be an exception.