title: Inhibition of the androgen receptor as a novel mechanism of taxol chemotherapy in prostate cancer.
abstract: Taxol chemotherapy is one of the few therapeutic options for men with castration-resistant prostate cancer (CRPC). However, the working mechanisms for Taxol are not fully understood. Here, we showed that treatment of 22Rv1, a PTEN-positive CRPC cell line, with paclitaxel and its semisynthetic analogue docetaxel decreases expression of the androgen receptor (AR)-activated genes prostate-specific antigen (PSA) and Nkx3.1 but increases expression of the AR repression gene maspin, suggesting that Taxol treatment inhibits AR activity. This was further supported by the observation that the activity of AR luciferase reporter genes was inhibited by paclitaxel. In contrast, paclitaxel treatment failed to inhibit AR activity in the PTEN-null CRPC cell line C4-2. However, pretreatment of C4-2 cells with the phosphoinositide 3-kinase inhibitor LY294002 restored paclitaxel inhibition of the AR. Treatment of 22Rv1 xenografts in mice with docetaxel induced mitotic arrest and a decrease in PSA expression in tumor cells adjacent to vascular vessels. We further showed that paclitaxel induces nuclear accumulation of FOXO1, a known AR suppressive nuclear factor, and increases the association of FOXO1 with AR proteins in the nucleus. FOXO1 knockdown with small interfering RNA attenuated the inhibitory effect of paclitaxel on AR transcriptional activity, expression of PSA and Nkx3.1, and cell survival. These data reveal a previously uncharacterized, FOXO1-mediated, AR-inhibitory effect of Taxol in CRPC cells that may play an important role in Taxol-mediated inhibition of CRPC growth.
authors.affiliation: Masonic Cancer Center and Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis, Minnesota 55455, USA.
authors.forename: Lu
authors.initials: L
authors.lastname: Gan
authors.forename: Shuai
authors.initials: S
authors.lastname: Chen
authors.forename: Yuwei
authors.initials: Y
authors.lastname: Wang
authors.forename: Akira
authors.initials: A
authors.lastname: Watahiki
authors.forename: Laura
authors.initials: L
authors.lastname: Bohrer
authors.forename: Zhen
authors.initials: Z
authors.lastname: Sun
authors.forename: Yuzhuo
authors.initials: Y
authors.lastname: Wang
authors.forename: Haojie
authors.initials: H
authors.lastname: Huang
mesh_terms: D059002:Androgen Receptor Antagonists; D000728:Androgens / Q000494:pharmacology; D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology; D000972:Antineoplastic Agents, Phytogenic / Q000627:therapeutic use; D017209:Apoptosis / Q000187:drug effects; D015153:Blotting, Western; D047369:Chromatin Immunoprecipitation; D002867:Chromones / Q000494:pharmacology; D000077143:Docetaxel; D004791:Enzyme Inhibitors / Q000494:pharmacology; D000071161:Forkhead Box Protein O1; D051858:Forkhead Transcription Factors / Q000235:genetics / Q000378:metabolism; D006801:Humans; D015151:Immunoblotting; D007124:Immunoenzyme Techniques; D008156:Luciferases / Q000378:metabolism; D008297:Male; D051379:Mice; D016688:Mice, Inbred NOD; D016513:Mice, SCID; D009025:Morpholines / Q000494:pharmacology; D009919:Orchiectomy; D051059:PTEN Phosphohydrolase / Q000235:genetics / Q000378:metabolism; D017239:Paclitaxel / Q000627:therapeutic use*; D000081082:Phosphoinositide-3 Kinase Inhibitors; D017430:Prostate-Specific Antigen / Q000235:genetics / Q000378:metabolism; D011471:Prostatic Neoplasms / Q000188:drug therapy* / Q000378:metabolism* / Q000473:pathology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000494:pharmacology; D011944:Receptors, Androgen / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D043823:Taxoids / Q000494:pharmacology*
chemical_list: D059002:Androgen Receptor Antagonists; D000728:Androgens; D000970:Antineoplastic Agents; D000972:Antineoplastic Agents, Phytogenic; D002867:Chromones; D004791:Enzyme Inhibitors; C085126:FOXO1 protein, human; D000071161:Forkhead Box Protein O1; D051858:Forkhead Transcription Factors; C467200:Foxo1 protein, mouse; D009025:Morpholines; D000081082:Phosphoinositide-3 Kinase Inhibitors; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D011944:Receptors, Androgen; D043823:Taxoids; D000077143:Docetaxel; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; D008156:Luciferases; D051059:PTEN Phosphohydrolase; C494929:PTEN protein, human; D017430:Prostate-Specific Antigen; D017239:Paclitaxel