Cytostatic and cytotoxic effects of tumor necrosis factor alpha on MCF-7 human breast tumor cells are differently inhibited by glucocorticoid hormones.
To investigate the mechanisms of growth inhibition exerted by TNF-alpha on tumor cells in vitro, we analyzed the cytokine effects on growth and cell-cycle parameters of cultured MCF-7 human breast cancer cells. TNF-alpha exerted a dose-dependent inhibition of MCF-7 cell growth, which reached its maximum at 1000 U/ml TNF-alpha concentrations. Flow-cytometric analysis of cell nuclei revealed two main components in TNF-alpha activity: an earlier cytostatic effect (G1/S block), was followed by nuclear shrinkage and cytolysis. The 55-60-kDa TNF-alpha receptor is involved in the growth inhibitory activity of the cytokine, since the H398 anti-55-kDa receptor antibody significantly counteracted the cytostatic and cytotoxic effects of TNF-alpha while an antibody (htr-9) with agonistic activity on the same receptor produced both cytostasis and cytolysis. Culture conditions strongly influenced the MCF-7 cell response to TNF-alpha. Serum deprivation of log-growing (i.e., high S phase percentage) cultures potentiated the cytotoxic effect, while reduction in S phase cell percentage by preculture in serum-free medium resulted in a significant inhibition of TNF-alpha action. Mitogenic hormones, such as insulin and 17 beta-estradiol+insulin, restored the sensitivity of MCF-7 cells precultured in serum-free medium to both the cytostatic and cytolytic effects of TNF-alpha. The synthetic glucocorticoid hormone dexamethasone, at micromolar concentrations, counteracted the TNF-alpha effect on MCF-7 cell growth. Flow-cytometric analysis showed that dexamethasone did not antagonize the cytostatic activity of either TNF-alpha or htr-9 agonistic antibody, but only the subsequent cytolysis.(ABSTRACT TRUNCATED AT 250 WORDS)
Pagliacci
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MC
Istituti di Clinica Medica 1 e Farmacologia Medica, Perugia University Medical School, Italy.
Fumi
G
G
Migliorati
G
G
Grignani
F
F
Riccardi
C
C
Nicoletti
I
I
D000906:Antibodies / Q000494:pharmacology; D001943:Breast Neoplasms; D002453:Cell Cycle / Q000187:drug effects*; D016923:Cell Death / Q000187:drug effects*; D002455:Cell Division / Q000187:drug effects*; D002460:Cell Line; D002467:Cell Nucleus / Q000187:drug effects; D016895:Culture Media, Serum-Free; D003907:Dexamethasone / Q000494:pharmacology*; D004958:Estradiol / Q000494:pharmacology; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D007328:Insulin / Q000494:pharmacology; D007700:Kinetics; D018124:Receptors, Tumor Necrosis Factor / Q000276:immunology / Q000502:physiology; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors / Q000633:toxicity*
D000906:Antibodies; D016895:Culture Media, Serum-Free; D007328:Insulin; D018124:Receptors, Tumor Necrosis Factor; D014409:Tumor Necrosis Factor-alpha; D004958:Estradiol; D003907:Dexamethasone