Androgen receptor-mediated apoptosis is regulated by photoactivatable androgen receptor ligands.
We have studied nonsteroidal ligands of the human androgen receptor (hAR) and have shown elsewhere that when photoactivated by visible light they collide with O2 to yield singlet oxygens (1O2) in vitro. Here we report cell killing after brief light activation (405 nm) of 1,2,3,4-tetrahydro-2,2-dimethyl-6-(trifluoromethyl)-8-pyridono[5,6-g]quinoline (TDPQ) in human prostate tumor cells. TDPQ/AR complexes were required for the death response because AR-positive LNCaP cells were killed, whereas AR-negative PC-3 cells were resistant. Excess dihydrotestosterone (DHT) blocked the TDPQ effect when the two were added together; irradiation of cells containing DHT alone had no effect. When LNCaP AR expression was suppressed using small interfering oligonucleotides targeting AR, photocytotoxicity was diminished. Conversely, stable transfection of hAR into PC-3 cells made the cells photosensitive to TDPQ. Similar results were obtained using a structural isomer of TDPQ, and also the synthetic steroidal AR ligand R1881. Cell death occurred via apoptosis as demonstrated by annexin V immunostaining, nuclear condensation, and caspase inhibition. Death involved oxidative stress, because it was prevented by addition of the antioxidant ascorbic acid during photoactivation. Detection of elevated levels of 8-hydroxy-2'-deoxyguanosine in nuclei of irradiated cells indicated oxidative DNA damage. Apoptosis spread into adjacent nonirradiated cells by direct cell-cell contacts, indicative of a bystander effect. Other photoactivatable ligands are described, implying a general method for ablation of cells bearing specific nuclear hormone receptors.
Laboratory of Reproductive and Developmental Toxicology, National Institute of Environmental Health Sciences, III T.W. Alexander Drive, Research Triangle Park, North Carolina 27709, USA.
Boris
B
Risek
Piotr
P
Bilski
Annette B
AB
Rice
William T
WT
Schrader
D021581:Active Transport, Cell Nucleus / Q000187:drug effects; D059002:Androgen Receptor Antagonists; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology* / Q000528:radiation effects; D001483:Base Sequence; D045744:Cell Line, Tumor; D004249:DNA Damage; D013196:Dihydrotestosterone / Q000494:pharmacology; D006801:Humans; D008024:Ligands; D008297:Male; D015741:Metribolone / Q000494:pharmacology / Q000528:radiation effects; D008954:Models, Biological; D018384:Oxidative Stress; D018462:Photobiology; D010778:Photochemotherapy; D017319:Photosensitizing Agents / Q000494:pharmacology; D011471:Prostatic Neoplasms / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism; D011725:Pyridines / Q000494:pharmacology / Q000528:radiation effects; D015363:Quinolones / Q000494:pharmacology / Q000528:radiation effects; D034741:RNA, Small Interfering / Q000235:genetics; D011944:Receptors, Androgen / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D014162:Transfection
C410798:AR protein, human; D059002:Androgen Receptor Antagonists; D008024:Ligands; D017319:Photosensitizing Agents; D011725:Pyridines; D015363:Quinolones; D034741:RNA, Small Interfering; D011944:Receptors, Androgen; D011994:Recombinant Proteins; D013196:Dihydrotestosterone; D015741:Metribolone