chiniofon and Glioblastoma

Glioblastoma multiforme (GBM) is a deadly grade IV brain tumor. Radiation in combination with temozolomide (TMZ), the current chemotherapeutic for GBMs, only provides 12-14 months survival post diagnosis. Because GBMs are dependent on both activation of the DNA damage pathway and the endoplasmic reticulum (ER) stress response, we asked if a novel ER stress inducing agent, JLK1486, increases the efficacy of TMZ.We found that the combination of TMZ+JLK1486 resulted in decreased proliferation in a panel of adherent GBM cells lines and reduced secondary sphere formation in non-adherent and primary lines. Decreased proliferation correlated with increased cell death due to apoptosis. We found prolonged ER stress in TMZ+JLK1486 treated cells that resulted in sustained activation of the unfolded protein response (UPR) through increased levels of BiP, ATF4, and CHOP. In addition, TMZ+JLK1486 treatment caused decreased RAD51 levels, impairing DNA damage repair. Furthermore, we found delayed time to tumor doubling in TMZ+JLK1486 treated mice.Our data shows that the addition of JLK1486 to TMZ increases the efficaciousness of the treatment by decreasing proliferation and inducing cell death. We propose increased cell death is due to two factors. One, prolonged ER stress driving the expression of the pro-apoptotic transcription factor CHOP, and, second, unresolved DNA double strand breaks, due to decreased RAD51 levels. The combination of TMZ+JLK1486 is a potential novel therapeutic combination and suggests an inverse relationship between unresolved ER stress and the DNA damage response pathway.

Topics: Animals; Antineoplastic Combined Chemotherapy Protocols; Apoptosis; Brain Neoplasms; Cell Line, Tumor; Dacarbazine; DNA Repair; Endoplasmic Reticulum Stress; Glioblastoma; Humans; Hydroxyquinolines; Male; Mice; Mice, Nude; Temozolomide; Xenograft Model Antitumor Assays

Glioblastoma multiforme (GBM) is the most aggressive form of brain cancer with marginal life expectancy. Based on the assumption that GBM cells gain functions not necessarily involved in the cancerous process, patient-derived glioblastoma cells (GCs) were screened to identify cellular processes amenable for development of targeted treatments. The quinine-derivative NSC13316 reliably and selectively compromised viability. Synthetic chemical expansion reveals delicate structure-activity relationship and analogs with increased potency, termed Vacquinols. Vacquinols stimulate death by membrane ruffling, cell rounding, massive macropinocytic vacuole accumulation, ATP depletion, and cytoplasmic membrane rupture of GCs. The MAP kinase MKK4, identified by a shRNA screen, represents a critical signaling node. Vacquinol-1 displays excellent in vivo pharmacokinetics and brain exposure, attenuates disease progression, and prolongs survival in a GBM animal model. These results identify a vulnerability to massive vacuolization that can be targeted by small molecules and point to the possible exploitation of this process in the design of anticancer therapies.

Topics: Animals; Brain Neoplasms; Cell Death; Glioblastoma; Heterografts; Humans; Hydroxyquinolines; MAP Kinase Kinase 4; Mice; Neoplasm Transplantation; Pinocytosis; Piperidines; Quinolines; Small Molecule Libraries; Vacuoles; Zebrafish

N,N-bis-(8-hydroxyquinoline-5-yl methyl)-benzyl substituted amines (HQNBA) represent a new class of compounds showing anti-cancer activity. At the chemical level the compounds were shown to react preferentially with thiol radicals which may lead to unfolded cysteine containing proteins and subsequent ER-stress. At the molecular level, treatment of U87 cells with this class of derivatives induced an over-expression of stress genes, including P53 and numerous P53 target genes. By generating shRNA U87 cell clones impaired in P53 expression we found that P53 mediates neither proliferation arrest of treated U87 cells nor over-expression of potential P53 targets. Moreover, we discovered that a representative HQNBA derivative (JLK1486) induces strong but transient senescence in U87 cells in a P53-independent manner. We demonstrate that, in contrast to its effect on established glioblastoma cell lines, JLK1486 induces extensive death of primary glioblastoma cells. We provide evidence that both caspase 3, and 7 activation, and cathepsin B and D activities account for at least part of this cell death.

Topics: Amines; Antineoplastic Agents; Brain Neoplasms; Cell Culture Techniques; Cell Death; Cell Line, Tumor; Cell Movement; Cell Proliferation; Cellular Senescence; Drug Evaluation, Preclinical; Glioblastoma; Humans; Hydroxyquinolines; Receptors, CXCR4; RNA, Small Interfering; Tumor Cells, Cultured; Tumor Suppressor Protein p53