On-target JAK2/STAT3 inhibition slows disease progression in orthotopic xenografts of human glioblastoma brain tumor stem cells

• Published in: Neuro-oncology (Charlottesville, Va.) Vol. 15; no. 2; pp. 198 - 207
• Main Authors: Stechishin, Owen D, Luchman, H Artee, Ruan, Yibing, Blough, Michael D, Nguyen, Stephanie A, Kelly, John J, Cairncross, J Gregory, Weiss, Samuel
• Format: Journal Article
• Language: English
• Published: England Oxford University Press 01-02-2013
• Subjects: Aged; Animals; Apoptosis; Basic and Translational Investigations; Blotting, Western; Brain Neoplasms - metabolism; Brain Neoplasms - pathology; Brain Neoplasms - prevention & control; Cell Proliferation; Disease Progression; DNA Methylation; DNA Modification Methylases - genetics; DNA Repair Enzymes - genetics; Female; Flow Cytometry; Glioblastoma - metabolism; Glioblastoma - pathology; Glioblastoma - prevention & control; Humans; Immunoenzyme Techniques; Janus Kinase 2 - antagonists & inhibitors; Janus Kinase 2 - genetics; Janus Kinase 2 - metabolism; Male; Mice; Mice, Inbred NOD; Mice, SCID; Middle Aged; Neoplastic Stem Cells - metabolism; Neoplastic Stem Cells - pathology; Promoter Regions, Genetic - genetics; PTEN Phosphohydrolase - metabolism; Pyridines - pharmacology; Receptor, Epidermal Growth Factor - metabolism; RNA, Small Interfering - genetics; Signal Transduction; STAT3 Transcription Factor - antagonists & inhibitors; STAT3 Transcription Factor - genetics; STAT3 Transcription Factor - metabolism; Triterpenes - pharmacology; Tumor Cells, Cultured; Tumor Suppressor Protein p53 - metabolism; Tumor Suppressor Proteins - genetics; Tyrphostins - pharmacology; Xenograft Model Antitumor Assays
• ISSN: 1522-8517; 1523-5866
• DOI: 10.1093/neuonc/nos302

Glioblastoma multiforme (GBM) is characterized by an aggressive clinical course, therapeutic resistance, and striking molecular heterogeneity. GBM-derived brain tumor stem cells (BTSCs) closely model this molecular heterogeneity and likely have a key role in tumor recurrence and therapeutic resistance. Emerging evidence indicates that Janus kinase (JAK)2/signal transducer and activator of transcription (STAT)3 is an important mediator of tumor cell survival, growth, and invasion in a large group of GBM. Here, we used a large set of molecularly heterogeneous BTSCs to evaluate the translational potential of JAK2/STAT3 therapeutics.
BTSCs were cultured from GBM patients and MGMT promoter methylation, and the mutation statuses of EGFR, PTEN, and TP53 were determined. Endogenous JAK2/STAT3 activity was assessed in human GBM tissue, BTSCs, and orthotopic xenografts by immunohistochemistry and Western blotting. STAT3 short hairpin (sh)RNA, cucurbitacin-I, and WP1066 were used to inhibit JAK2/STAT3 activity in vitro and in vivo.
The JAK2/STAT3 pathway was demonstrated to be highly activated in human GBM, molecularly heterogeneous BTSCs derived from these tumors, and BTSC xenografts. STAT3 shRNA knockdown or cucurbitacin-I and WP1066 administration resulted in on-target JAK2/STAT3 inhibition and dramatically reduced BTSC survival regardless of endogenous MGMT promoter methylation or EGFR, PTEN, and TP53 mutational status. BTSC orthotopic xenografts maintained the high levels of activated JAK2/STAT3 seen in their parent human tumors. Intraperitoneal WP1066 reduced intratumoral JAK2/STAT3 activity and prolonged animal survival.
Our study demonstrates the in vitro and in vivo efficacy of on-target JAK2/STAT3 inhibition in heterogeneous BTSC lines that closely emulate the genomic and tumorigenic characteristics of human GBM.