Effects of steroid hormones on nuclear membrane and membrane-bound heterochromatin from breast cancer cells evaluated by fractal morphometry.
OBJECTIVE
To evaluate the effect of steroid hormones on the ultrastructure of nuclear heterochromatin and perinuclear membranes in human MCF-7 breast cancer cells.


METHODS
MCF-7 cells were cultured briefly (five minutes) in the presence of 10(-9) M estrogen 17 beta-estradiol, a stimulator of cell proliferation and/or 10(-9) M glucocorticoid dexamethasone. Changes in the morphologic complexity of nuclear membrane-bound heterochromatin (NMBHC) and nuclear membranes (ENM) were assessed by means of the fractal capacity dimension, D, a noneuclidean geometric descriptor of complex, irregular bodies.


RESULTS
17 beta-estradiol (10(-9) M) enhanced the ultrastructural irregularity of NMBHC, as documented by the increased value of D, whereas dexamethasone (10(-9) M) reduced it when compared to NMBHC from untreated MCF-7 control cells. In contrast, neither steroid modified ENM ultrastructure. Changes in the nuclear heterochromatin complexity induced by estrogen 17 beta-estradiol occurred concomitantly with functional changes at the cell periphery, such as activation of the phospholipase C, a cell membrane-associated enzyme involved in signal transduction. Dexamethasone reduced the ultrastructural complexity of NMBHC without affecting functional processes.


CONCLUSIONS
Fractal morphometry proved its usefulness in quantifying early ultrastructural changes in nuclear components induced in MCF-7 cells by steroid hormones, 17 beta-estradiol and dexamethasone.
Losa
G A
GA
Laboratory of Cellular Pathology, Institute of Pathology, Locarno, Switzerland. glosa@guest.cscs.ch
Graber
R
R
Baumann
G
G
Nonnenmacher
T F
TF
D001943:Breast Neoplasms / Q000235:genetics* / Q000473:pathology; D003907:Dexamethasone / Q000494:pharmacology*; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D017709:Fractals; D006570:Heterochromatin / Q000187:drug effects* / Q000235:genetics; D006801:Humans; D009685:Nuclear Envelope / Q000187:drug effects* / Q000235:genetics / Q000648:ultrastructure; D014407:Tumor Cells, Cultured / Q000187:drug effects / Q000473:pathology
D006570:Heterochromatin; D004958:Estradiol; D003907:Dexamethasone