Effect of medroxyprogesterone acetate on proliferation and cell cycle kinetics of human mammary carcinoma cells.

The effect of medroxyprogesterone acetate (MPA) on breast cancer cell proliferation kinetics was investigated in ten human breast cell lines growing as monolayer cultures. Significant inhibition of growth occurred only in the estrogen receptor-positive, progesterone receptor-positive cell lines, T-47D, MCF-7, ZR 75-1, BT 474, and MDA-MB-361. Among these cell lines sensitivity to MPA varied widely; concentrations required for 20% inhibition of growth ranged from 0.04 nM for T-47D to greater than 100 nM for ZR 75-1 cells. Furthermore, although the most sensitive line, T-47D, had the highest level of PR, sensitivity to MPA was not correlated with PR levels among the responsive cell lines. More detailed studies were undertaken with the T-47D cell line. The growth-inhibitory response was confined to the progestins: MPA, ORG 2058, R5020, and progesterone, while androgens, estrogens, and glucocorticoids were without effect over the same concentration range (0.1-100 nM). MPA-induced growth inhibition was associated with a significant decrease in the proportion of S-phase cells with an accumulation of cells in the G0-G1 phase of the cell cycle. Cells began to accumulate in G0-G1 after 12 h of drug treatment and the effect was maximal by 24 h, i.e., maximal effects were observed during the first cell cycle following drug treatment. By contrast, significant accumulation in G0-G1 required exposure of MCF-7 cells to MPA for at least two cell cycle times, i.e., 48 h and the effect was still increasing at 96 h. Stathmokinetic studies revealed that in both cell lines accumulation in the G0-G1 phase was due to an MPA-induced increase in the G1 transit time. These data indicate that MPA and other progestins have direct growth inhibitory effects on estrogen receptor-positive and progesterone receptor-positive human breast cancer cells in vitro and these effects can be accounted for by a decrease in the rate at which cells traverse the G1 phase of the cell cycle.

[Research on the activity and quantity of natural killer cells and T lymphocytes in myelodysplastic syndrome patients].

24 patients with myelodysplastic syndrome (MDS) were examined for the following items. T lymphocyte subsets of five subtypes of MDS examined with monoclonal antibody were less than that in normal controls. After incubation of peripheral blood lymphocytes with PHA at 37 degrees C with 5% carbon dioxide, the amount of HLA-DR positive cells and NKH1 positive cells were less than normal, NK cell activity was measured with cytotoxicity assay using 51 Cr labeled target K562 cells, the results showed that NK activity in MDS was less than that in controls. As mentioned above, the results indicated that the activity and quantity of T lymphocytes and NK cells in MDS were abnormal.

[Significance of the serum level of Cu, Zn, Mn, Cr and Ni in acute leukemia].

Serum Cu and Ni increase, while serum Zn and Mn decrease in acute leukemia patients. The results of this study showed that there is correlation between the change of the level of serum Ni and the condition of the patient. Higher level of serum Ni in patients with acute leukemia indicates inefficient chemotherapy and poor prognosis. The results suggest that the level of serum Ni may be used as an in acute leukemia. Increase of serum Ni with simultaneous decrease of serum Mn may be an instinctive reflection in acute leukemia.

Effects of 1,25-dihydroxyvitamin D3 on cell-cycle kinetics of T 47D human breast cancer cells.

The replication of several human and animal cancer cell lines is regulated in vitro and in vivo by 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3], the hormonally active form of vitamin D3. We have examined the effects of concentrations of 1,25-(OH)2D3, which inhibit cellular replication, on the cell-cycle kinetics of a 1,25-(OH)2D3-responsive human breast cancer cell line, T 47D. After 6 or 7 days of treatment, a time period representing approximately five cell population doublings of control cultures, concentrations of 1,25-(OH)2D3 in the range 10(-9) M to 10(-6) M caused a time- and concentration-dependent decrease in cell numbers. Treatment of cells growing in charcoal-treated fetal calf serum with 10(-8) M 1,25-(OH)2D3 for 6 days reduced cell numbers to 49% +/- 9% (n = 9) of control, and this was associated with a marked increase in the proportion of cells in the G2 + M phase of the cell cycle from 9.7% +/- 0.5% (n = 11) to 19.6% +/- 2.3% (n = 9), significant by paired analysis (P less than 0.002). At higher concentrations of 1,25-(OH)2D3 (10(-7)-10(-6) M), there was a concentration-dependent decline in S phase and increases in both G0/G1 and G2 + M phase cells. Detailed analysis of the temporal changes in cell-cycle phase distribution following treatment with 2.5 X 10(-8) and 10(-7) M 1,25-(OH)2D3 showed an initial accumulation of cells in G0/G1 and depletion of S phase cells during the first 24 hr of treatment. This decline in S phase cells was not accompanied by a decline in % G2 + M indicating a transition delay in G2 or mitosis. At the lower dose these changes returned to control values at 48 hr and at later times were associated with a slight but consistent decline in G0/G1 phase and an increase in G2 + M. In contrast cells treated with 10(-7) M 1,25-(OH)2D3 had significantly elevated % G0/G1 cells at days 2 and 3, consistent with a transition delay through G1 phase. This was confirmed in stathmokinetic experiments which demonstrated an approximate sevenfold decrease in the rate of exit of cells from G0/G1 following 4 days of exposure to 10(-7) M 1,25-(OH)2D3. This accumulation of cells in G0/G1 was accompanied by a fall in % S phase cells.(ABSTRACT TRUNCATED AT 400 WORDS)

Regulation of epidermal growth factor receptor by progestins and glucocorticoids in human breast cancer cell lines.

Human breast cancer cells secrete a number of autocrine peptides which modulate their proliferation rates. The known effects of steroid hormones on breast cancer cell proliferation may be mediated in part by altering the production of these growth factors and/or their interactions with cellular receptor sites. Receptors for epidermal growth factor (EGF), which also bind the autocrine growth factor, alpha-transforming growth factor, are present on a number of breast cancer cell lines and it has previously been shown that T-47D and MCF-7 cells respond to progestins with an increase in the concentration of EGF receptors (EGF-R). In the present study we examined the effects of both progestins and glucocorticoids on EGF binding in 10 human breast cell lines. Five of these lines were progesterone receptor positive and all lines expressed the glucocorticoid receptor (GR). All cell lines were initially incubated for 24 hr with increasing concentrations of the synthetic progestin, medroxyprogesterone acetate (MPA), and the level of specifically bound EGF was determined. An increase in specific binding of EGF was confirmed in two PR-positive lines but, in addition, increases in EGF binding were observed in 4 PR-negative cell lines. In these last lines the synthetic glucocorticoid, dexamethasone, was a more potent inducer of EGF binding than MPA, a known glucocorticoid agonist, while the high-affinity PR ligand, ORG 2058, was without effect. Furthermore, MPA competed with dexamethasone for binding to GR in these cell lines, supporting the view that the induction of EGF binding by MPA in these cells was mediated via the GR. This conclusion was further supported by studies in which addition of the glucocorticoid and progestin antagonist, RU 486, inhibited the effect of ORG 2058 in two cell lines and completely abrogated the effect of dexamethasone in two other lines. Detailed binding studies revealed that the increase in EGF binding was accompanied by an increase in the concentration of EGF-R. This effect was observed when EGF binding was assayed at either 0 degree or 37 degrees C. Further studies demonstrated that the increases in EGF binding following ORG 2058 and dexamethasone treatment were accompanied by increases in EGF-R mRNA levels. Our data illustrate that the binding of EGF by some human breast cancer cells can be regulated by both progestins and glucocorticoids acting via their respective receptors and inducing increases in EGF-R mRNA levels.