Generation of Prostate Tumor―Initiating Cells Is Associated with Elevation of Reactive Oxygen Species and IL-6/STAT3 Signaling

• Published in: Cancer research (Chicago, Ill.) Ill.), 2013-12, Vol.73 (23), p.7090-7100
• Main Authors: YI QU, OYAN, Anne Margrete, MOLVEN, Anders, BIAOYANG LIN, ZHANG, Wei-Dong, MCCORMACK, Emmet, KALLAND, Karl-Henning, KE, Xi-Song, RUNHUI LIU, YAPING HUA, JIGANG ZHANG, HOVLAND, Randi, POPA, Mihaela, XIAOJUN LIU, BROKSTAD, Karl A, SIMON, Ronald
• Format: Article
• Language: English
• Subjects: Animals; Antineoplastic agents; Biological and medical sciences; Cell Proliferation - drug effects; Gynecology. Andrology. Obstetrics; Humans; Interleukin-6 - physiology; Male; Male genital diseases; Medical sciences; Mice; Mice, Inbred BALB C; Mice, Nude; Mice, Transgenic; Neoplastic Stem Cells - drug effects; Neoplastic Stem Cells - pathology; Neoplastic Stem Cells - physiology; Nephrology. Urinary tract diseases; Pharmacology. Drug treatments; Prostatic Neoplasms - pathology; Reactive Oxygen Species - metabolism; Reactive Oxygen Species - pharmacology; Signal Transduction - drug effects; Signal Transduction - physiology; Spheroids, Cellular - drug effects; Spheroids, Cellular - pathology; Spheroids, Cellular - physiology; STAT3 Transcription Factor - physiology; Tumor Cells, Cultured; Tumors; Tumors of the urinary system; Urinary tract. Prostate gland
• ISSN: 0008-5472; 1538-7445
• DOI: 10.1158/0008-5472.CAN-13-1560

How prostate cancer is initiated remains a topic of debate. In an effort to establish a human model of prostate carcinogenesis, we adapted premalignant human prostate EPT2-D5 cells to protein-free medium to generate numerous tight prostate spheres (D5HS) in monolayer culture. In contrast to EPT2-D5 cells, the newly generated D5HS efficiently formed large subcutaneous tumors and subsequent metastases in vivo, showing the tumorigenicity of D5HS spheres. A striking production of interleukin (IL)-6 mRNA and protein was found in D5HS cells. The essential roles of IL-6 and the downstream STAT3 signaling in D5HS tumor sphere formation were confirmed by neutralizing antibody, chemical inhibitors, and fluorescent pathway reporter. In addition, elevated reactive oxygen species (ROS) produced upon protein depletion was required for the activation of IL-6/STAT3 in D5HS. Importantly, a positive feedback loop was found between ROS and IL-6 during tumor sphere formation. The association of ROS/IL-6/STAT3 to the carcinogenesis of human prostate cells was further examined in xenograft tumors and verified by limiting dilution implantations. Collectively, we have for the first time established human prostate tumor-initiating cells based on physiologic adaption. The intrinsic association of ROS and IL-6/STAT3 signaling in human prostate carcinogenesis shed new light on this relationship and define therapeutic targets in this setting.