Expression of transforming growth factor alpha antisense mRNA inhibits the estrogen-induced production of TGF alpha and estrogen-induced proliferation of estrogen-responsive human breast cancer cells.
To ascertain if 17 beta-estradiol (E2)-induced proliferation could be attenuated by blocking the expression of endogenous transforming growth factor alpha (TGF alpha), estrogen receptor (ER)-positive, estrogen-responsive MCF-7 or ZR-75-1 cells and ER-negative, estrogen-nonresponsive MDA-MB-468 or HS-578T cells were infected with a recombinant amphotropic, replication-defective retroviral expression vector containing a 435 base pair (bp) Apa1-Eco R1 coding fragment of the human TGF alpha cDNA oriented in the 3' to 5' direction and under the transcriptional control of an internal heavy metal-inducible mouse metallothionein (MT-1) promoter and containing the neomycin (neo) resistance gene. E2-stimulated expression of endogenous TGF alpha mRNA was inhibited by 4-5-fold, and the production of TGF alpha protein was inhibited by 50-80% when M-1 mass-infected MCF-7 or MZ-1 mass-infected ZR-75-1 cells were treated with 0.75-1 microM CdCl2, whereas in comparably treated parental MCF-7 or ZR-75-1 cells there was no significant effect upon these parameters. E2-stimulated anchorage-dependent growth (ADG) and anchorage-independent growth (AIG) of the M-1 or MZ-1 cells was inhibited by 60-90% following CdCl2 treatment. In contrast, neither the ADG nor AIG of the parental noninfected MCF-7 or ZR-75-1 cells that were maintained in the absence or presence of E2 was affected by comparable concentrations of CdCl2. The ADG and AIG of TGF alpha antisense MD-1 mass-infected MDA-MB-468 cells that express high levels of endogenous TGF alpha mRNA were also inhibited by 1 microM CdCl2, whereas the ADG and AIG of MH-1 mass-infected HS-578T cells, a TGF alpha-negative cell line, were unaffected by CdCl2 treatment. These results suggest that TGF alpha may be one important autocrine intermediary in regulating estrogen-induced cell proliferation.
Kenney
N J
NJ
Department of Microbiology, College of Medicine, Howard University, Washington, DC 20001.
Saeki
T
T
Gottardis
M
M
Kim
N
N
Garcia-Morales
P
P
Martin
M B
MB
Normanno
N
N
Ciardiello
F
F
Day
A
A
Cutler
M L
ML
D001943:Breast Neoplasms / Q000473:pathology*; D002455:Cell Division / Q000187:drug effects; D004958:Estradiol / Q000494:pharmacology*; D006801:Humans; D016372:RNA, Antisense / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism*; D012334:RNA, Neoplasm / Q000378:metabolism; D016211:Transforming Growth Factor alpha / Q000037:antagonists & inhibitors* / Q000235:genetics* / Q000378:metabolism; D014407:Tumor Cells, Cultured
D016372:RNA, Antisense; D012333:RNA, Messenger; D012334:RNA, Neoplasm; D016211:Transforming Growth Factor alpha; D004958:Estradiol