An androgen receptor mutation in the MDA-MB-453 cell line model of molecular apocrine breast cancer compromises receptor activity.
Recent evidence indicates that the estrogen receptor-α-negative, androgen receptor (AR)-positive molecular apocrine subtype of breast cancer is driven by AR signaling. The MDA-MB-453 cell line is the prototypical model of this breast cancer subtype; its proliferation is stimulated by androgens such as 5α-dihydrotestosterone (DHT) but inhibited by the progestin medroxyprogesterone acetate (MPA) via AR-mediated mechanisms. We report here that the AR gene in MDA-MB-453 cells contains a G-T transversion in exon 7, resulting in a receptor variant with a glutamine to histidine substitution at amino acid 865 (Q865H) in the ligand binding domain. Compared with wild-type AR, the Q865H variant exhibited reduced sensitivity to DHT and MPA in transactivation assays in MDA-MB-453 and PC-3 cells but did not respond to non-androgenic ligands or receptor antagonists. Ligand binding, molecular modeling, mammalian two-hybrid and immunoblot assays revealed effects of the Q865H mutation on ligand dissociation, AR intramolecular interactions, and receptor stability. Microarray expression profiling demonstrated that DHT and MPA regulate distinct transcriptional programs in MDA-MB-453 cells. Gene Set Enrichment Analysis revealed that DHT- but not MPA-regulated genes were associated with estrogen-responsive transcriptomes from MCF-7 cells and the Wnt signaling pathway. These findings suggest that the divergent proliferative responses of MDA-MB-453 cells to DHT and MPA result from the different genetic programs elicited by these two ligands through the AR-Q865H variant. This work highlights the necessity to characterize additional models of molecular apocrine breast cancer to determine the precise role of AR signaling in this breast cancer subtype.
Dame Roma Mitchell Cancer Research Laboratories, Discipline of Medicine, The University of Adelaide and Hanson Institute, PO Box 14, Rundle Mall, Adelaide, South Australia 5000, Australia.
Nicole L
NL
Moore
Grant
G
Buchanan
Jonathan M
JM
Harris
Luke A
LA
Selth
Tina
T
Bianco-Miotto
Adrienne R
AR
Hanson
Stephen N
SN
Birrell
Lisa M
LM
Butler
Theresa E
TE
Hickey
Wayne D
WD
Tilley
D000595:Amino Acid Sequence; D000818:Animals; D001050:Apocrine Glands / Q000378:metabolism / Q000473:pathology; D001943:Breast Neoplasms / Q000145:classification / Q000235:genetics* / Q000473:pathology; D019556:COS Cells; D002277:Carcinoma / Q000145:classification / Q000235:genetics* / Q000473:pathology; D045744:Cell Line, Tumor; D002522:Chlorocebus aethiops; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008297:Male; D008958:Models, Molecular; D008962:Models, Theoretical; D008969:Molecular Sequence Data; D020125:Mutation, Missense / Q000502:physiology; D019899:Paracrine Communication / Q000235:genetics / Q000502:physiology; D011944:Receptors, Androgen / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism / Q000502:physiology*; D013329:Structure-Activity Relationship
D011944:Receptors, Androgen