title: CYP3A4 mediates growth of estrogen receptor-positive breast cancer cells in part by inducing nuclear translocation of phospho-Stat3 through biosynthesis of (±)-14,15-epoxyeicosatrienoic acid (EET).
abstract: CYP3A4 expression in breast cancer correlates with decreased overall survival, but the mechanisms are unknown. Cytochrome P450 gene profiling by RNAi silencing demonstrates that CYP3A or 2C8 gene expression is specifically required for growth of the breast cancer lines MCF7, T47D, and MDA-MB-231. CYP3A4 silencing blocks the cell cycle at the G(2)/M checkpoint and induces apoptosis in the MCF7 line, thereby inhibiting anchorage-dependent growth and survival. CYP3A4 was profiled for NADPH-dependent arachidonic acid (AA) metabolism and synthesized AA epoxygenase products (±)-8,9-, (±)-11,12-, and (±)-14,15-epoxyeicosatrienoic acid (EET) (total turnover of ∼2 pmol/pmol CYP3A4/min) but not hydroxylase products (±)-15-, (±)-19-, or 20-hydroxyeicosatetraenoic acid. Furthermore, eicosanoid profiling revealed that MCF7 cells synthesize EETs in a CYP3A4-dependent manner. The (±)-14,15-EET regioisomer selectively rescues breast cancer cells from CYP3A4 silencing in a concentration-dependent fashion and promotes mitogenesis and anchorage-dependent cloning. Stat3 (Tyr-705) phosphorylation was inhibited by CYP3A4 silencing, providing a potential mechanism for CYP3A4 involvement in breast cancer cell growth. Silencing Stat3 blocks breast cancer cell growth and abrogates (±)-14,15-EET-induced proliferation, indicating a Stat3 requirement for (±)-14,15-EET-mediated cell growth. Although silencing of CYP3A4 reduces nuclear Tyr(P)-705-Stat3, (±)-14,15-EET restores this signaling process and promotes Tyr(P)-705-Stat3 translocation to the nucleus, suggesting that (±)-14,15-EET may be involved in an autocrine/paracrine pathway driving cell growth. These studies indicate that CYP3A4 is a highly active AA epoxygenase that promotes Stat3-mediated breast cancer cell growth in part through (±)-14,15-EET biosynthesis. Furthermore, these studies indicate an essential role for Stat3 as a mediator of epoxygenase activity in breast cancer.
authors.affiliation: From the Division of Hematology, Oncology, and Transplantation, University of Minnesota, Minneapolis, Minnesota 55455, USA.
authors.forename: Ranjana
authors.initials: R
authors.lastname: Mitra
authors.forename: Zhijun
authors.initials: Z
authors.lastname: Guo
authors.forename: Monica
authors.initials: M
authors.lastname: Milani
authors.forename: Clementina
authors.initials: C
authors.lastname: Mesaros
authors.forename: Mariangellys
authors.initials: M
authors.lastname: Rodriguez
authors.forename: Julia
authors.initials: J
authors.lastname: Nguyen
authors.forename: Xianghua
authors.initials: X
authors.lastname: Luo
authors.forename: Duncan
authors.initials: D
authors.lastname: Clarke
authors.forename: Jatinder
authors.initials: J
authors.lastname: Lamba
authors.forename: Erin
authors.initials: E
authors.lastname: Schuetz
authors.forename: David B
authors.initials: DB
authors.lastname: Donner
authors.forename: Narender
authors.initials: N
authors.lastname: Puli
authors.forename: John R
authors.initials: JR
authors.lastname: Falck
authors.forename: Jorge
authors.initials: J
authors.lastname: Capdevila
authors.forename: Kalpna
authors.initials: K
authors.lastname: Gupta
authors.forename: Ian A
authors.initials: IA
authors.lastname: Blair
authors.forename: David A
authors.initials: DA
authors.lastname: Potter
mesh_terms: D015126:8,11,14-Eicosatrienoic Acid / Q000031:analogs & derivatives* / Q000235:genetics / Q000378:metabolism; D021581:Active Transport, Cell Nucleus / Q000235:genetics; D001943:Breast Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D002455:Cell Division; D045744:Cell Line, Tumor; D051544:Cytochrome P-450 CYP3A / Q000235:genetics / Q000378:metabolism*; D005260:Female; D016195:G2 Phase; D020868:Gene Silencing; D006801:Humans; D009363:Neoplasm Proteins / Q000235:genetics* / Q000378:metabolism*; D010766:Phosphorylation / Q000235:genetics; D050796:STAT3 Transcription Factor / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000235:genetics
chemical_list: D009363:Neoplasm Proteins; D050796:STAT3 Transcription Factor; C494086:STAT3 protein, human; C046782:14,15-epoxy-5,8,11-eicosatrienoic acid; D051544:Cytochrome P-450 CYP3A; C510163:CYP3A4 protein, human; D015126:8,11,14-Eicosatrienoic Acid