cucurbitacin-i and Brain-Neoplasms

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.

Topics: Aged; Animals; Apoptosis; Blotting, Western; Brain Neoplasms; Cell Proliferation; Disease Progression; DNA Methylation; DNA Modification Methylases; DNA Repair Enzymes; ErbB Receptors; Female; Flow Cytometry; Glioblastoma; Humans; Immunoenzyme Techniques; Janus Kinase 2; Male; Mice; Mice, Inbred NOD; Mice, SCID; Middle Aged; Neoplastic Stem Cells; Promoter Regions, Genetic; PTEN Phosphohydrolase; Pyridines; RNA, Small Interfering; Signal Transduction; STAT3 Transcription Factor; Triterpenes; Tumor Cells, Cultured; Tumor Suppressor Protein p53; Tumor Suppressor Proteins; Tyrphostins; Xenograft Model Antitumor Assays

A variety of cancers, including malignant gliomas, show aberrant activation of STAT3, which plays a pivotal role in negative regulation of antitumor immunity. We hypothesized that inhibition of STAT3 signals would improve the efficacy of T cell adoptive transfer therapy by reversal of STAT3-induced immunosuppression in a murine GL261 intracranial glioma model. In vitro treatment of GL261 cells with JSI-124, a STAT3 inhibitor, reversed highly phosphorylated status of STAT3. Systemic i.p. administration of JSI-124 in glioma-bearing immunocompetent mice, but not athymic mice, resulted in prolonged survival, suggesting a role of adaptive immunity in the antitumor effect. Furthermore, JSI-124 promoted maturation of tumor-infiltrating CD11c(+) dendritic cells and activation of tumor-conditioned cytotoxic T cells, enhanced dendritic cells and GL261 production of CXCL-10, a critical chemokine for attraction of Tc1 cells. When i.p. JSI-124 administration was combined with i.v. transfer of Pmel-I mouse-derived type-1 CTLs (Tc1), glioma-bearing mice exhibited prolonged survival compared with i.p. JSI-124 or i.v. Tc1 therapy alone. Flow cytometric analyses of brain infiltrating lymphocytes revealed that JSI-124-treatment enhanced the tumor-homing of i.v. transferred Tc1 cells in a CXCL-10-dependent fashion. Systemic JSI-124 administration also up-regulated serum IL-15 levels, and promoted the persistence of transferred Tc1 in the host. These data suggest that systemic inhibition of STAT3 signaling can reverse the suppressive immunological environment of intracranial tumor bearing mice both systemically and locally, thereby promoting the efficacy of adoptive transfer therapy with Tc1.

Topics: Adoptive Transfer; Animals; Brain Neoplasms; Cell Line, Tumor; Cell Migration Inhibition; Cells, Cultured; Combined Modality Therapy; Glioma; Injections, Intraventricular; Mice; Mice, Inbred C57BL; Mice, Nude; Mice, Transgenic; Neoplasm Transplantation; Phosphorylation; STAT3 Transcription Factor; T-Lymphocyte Subsets; T-Lymphocytes, Cytotoxic; Triterpenes

JSI-124 (cucurbitacin I) is a selective inhibitor of Janus kinase/signal transducer and activator of transcription 3(JAK/STAT3) and has been shown to exert anti-proliferative and anti-tumor properties both in vitro and in vivo. As STAT3 activation has been implicated in the development of glioma, we investigated the therapeutic efficacy of JSI-124 on glioblastoma multiforme (GBM) by interfering with STAT3 pathway. In present study, two GBM cell lines, U251 and A172 cells, were treated with JSI-124. The results showed that the cell growth was inhibited significantly in a dose-and time-dependent manner. Further investigation illustrated that the levels of phosphorylated-STAT3 were decreased in GBM cells treated by JSI-124, concomitant with apoptosis augment and cell cycle arrest. Specially, JSI-124 induced G(2)/M accumulation via downregulation of cyclin B1 and cdc2 expression. Together these results suggested that inhibition of STAT3 by JSI-124 is a potential strategy for the development of the new glioblastoma multiforme therapeutics.

Topics: Antineoplastic Agents; Apoptosis; Brain Neoplasms; Cell Cycle; Cell Line, Tumor; Cell Proliferation; Dose-Response Relationship, Drug; G2 Phase; Glioblastoma; Humans; Mitosis; Triterpenes