Changes in protein tyrosine phosphatase type IVA member 1 and zinc finger protein 36 C3H type-like 1 expression demonstrate altered estrogen and progestin effect in medroxyprogesterone acetate-resistant and estrogen-independent breast cancer cell models.
Estrogen stimulates proliferation in hormone-responsive breast cancer cells. Progestins inhibit the estrogen-mediated growth in these cells and are used in the treatment of mammary carcinomas. We applied cDNA microarray and real-time RT-PCR methods to reveal 17beta-estradiol- and medroxyprogesterone acetate (MPA)-regulated genes in MCF-7 breast cancer cells. We identified six genes, two of which were novel MPA and/or 17beta-estradiol-regulated genes: protein tyrosine phosphatase type IVA, member 1 (PTP4A1) and zinc finger protein 36, C3H type-like 1 (ZFP36L1). PTP4A1 expression was upregulated by 17beta-estradiol and this was opposed by MPA treatment of the cells. ZFP36L1 proved to be a direct target of MPA. Since MPA has also been shown to bind to glucocorticoid- and androgen receptors, we studied the regulation of the genes with progesterone, synthetic progestin R5020, dexamethasone and dihydrotestosterone. We also assessed the expression and hormonal regulation of PTP4A1 and ZFP36L1 mRNA in MCF-7-derived MPA-resistant and estrogen-independent sublines. The regulation of PTP4A1 expression upon 17beta-estradiol and combined 17beta-estradiol and MPA treatment was completely reversed in the estrogen-independent and MPA-resistant sublines, respectively. This study suggests an important role for PTP4A1 in cell growth, and shows that MPA may potentiate the effect of 17beta-estradiol in the MPA-resistant breast cancer cells.
Pennanen
Pasi T
PT
Department of Cell Biology, Medical School, FIN-33014 University of Tampere, Tampere, Finland. pasi.pennanen@uta.fi
Sarvilinna
Nanna S
NS
Purmonen
Sami R
SR
Ylikomi
Timo J
TJ
D001943:Breast Neoplasms / Q000201:enzymology* / Q000235:genetics; D051817:Butyrate Response Factor 1 / Q000235:genetics* / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000235:genetics* / Q000378:metabolism; D045744:Cell Line, Tumor; D019008:Drug Resistance, Neoplasm / Q000187:drug effects; D004354:Drug Screening Assays, Antitumor; D004958:Estradiol / Q000494:pharmacology; D004967:Estrogens / Q000378:metabolism / Q000494:pharmacology*; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D017258:Medroxyprogesterone Acetate / Q000494:pharmacology*; D008565:Membrane Proteins / Q000235:genetics* / Q000378:metabolism; D020411:Oligonucleotide Array Sequence Analysis; D011372:Progestins / Q000494:pharmacology*; D017027:Protein Tyrosine Phosphatases / Q000235:genetics* / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction
D051817:Butyrate Response Factor 1; D018797:Cell Cycle Proteins; D004967:Estrogens; D008565:Membrane Proteins; D011372:Progestins; D012333:RNA, Messenger; C102034:ZFP36L1 protein, human; D004958:Estradiol; D017258:Medroxyprogesterone Acetate; C490198:PTP4A1 protein, human; D017027:Protein Tyrosine Phosphatases