title: Targeting CD133 improves chemotherapeutic efficacy of recurrent pediatric pilocytic astrocytoma following prolonged chemotherapy.
abstract: Pilocytic astrocytomas (PAs) are the most common pediatric central nervous system neoplasms. In the majority of cases these tumors are benign and receive favorable prognosis following gross total surgical resection. In patients with progressive or symptomatic tumors, aggressive surgical resection is generally not feasible, thus radiation or chemotherapy are accepted initial or adjuvant interventions. Due to serious long-lasting side-effects, radiation is limited in young children; therefore, chemotherapy is widely practiced as an adjuvant treatment for these patients. However, chemotherapy can promote the emergence of multidrug resistant tumor cells that are more malignant than those of the original tumor. CD133, a putative stem cell marker in normal tissue and malignant brain tumors, enhances multidrug resistant gene 1 (MDR1) expression following chemotherapy in adult malignant glioblastomas. This study examines the relationship between CD133 and MDR1 in pediatric PAs exposed to chemotherapy, with the goal of identifying therapeutic targets that manifest as a result of chemotherapy.
  
  
  
  Slides were obtained for 15 recurrent PAs, seven of which had received chemotherapy prior to surgical treatment for the recurrent tumor. These samples, as well as primary tumor tissue slides from the same patients were used to investigate CD133 and MDR1 expression via immunofluorescence. Archived frozen tissue samples from the same patients were used to examine CD133, MDR1 and PI3K-Akt-NF-κB signaling mediators, via western blot. Two drug resistant pediatric PA cell lines Res186 and Res199 were also used to evaluate the role of CD133 on cell response to cytotoxic therapy.
  
  
  
  CD133 and MDR1 were co-expressed and their expression was elevated in recurrent PAs from patients that had received chemotherapy, compared to patients that had not received chemotherapy. PI3K-Akt-NF-κB signaling mediator expression was also elevated in recurrent, chemotherapy-treated PA. Suppressing CD133 expression with siCD133 decreased levels of PI3K-Akt-NF-κB signaling mediators and MDR1, while increasing cell chemosensitivity, as indicated by quantification of apoptotic cells following chemotherapy.
  
  
  
  CD133 contributes to multidrug resistance by regulating MDR1 levels via the PI3K-Akt-NF-κB signal pathway not only in adult glioblastomas, but also in pediatric PAs. Targeting CD133, adjuvant to conventional chemotherapy may improve outcomes for children with recurrent PA.
authors.affiliation: Falk Brain Tumor Center, Division of Pediatric Neurosurgery, Northwestern University Feinberg School of Medicine, 225 E Chicago Ave, PO Box #28, Chicago, IL, 60611, USA. gxi@luriechildrens.org.|Development Biology Program, Stanley Manne Children's Research Institute, Ann & Robert H. Lurie Children's Hospital of Chicago, Northwestern University Feinberg School of Medicine, Chicago, IL, USA. gxi@luriechildrens.org.|Department of Neurological Surgery, Northwestern University Feinberg School of Medicine, Chicago, IL, USA. gxi@luriechildrens.org.
authors.forename: Guifa
authors.initials: G
authors.lastname: Xi
authors.affiliation: Falk Brain Tumor Center, Division of Pediatric Neurosurgery, Northwestern University Feinberg School of Medicine, 225 E Chicago Ave, PO Box #28, Chicago, IL, 60611, USA.
authors.forename: Yuping Derek
authors.initials: YD
authors.lastname: Li
authors.affiliation: Falk Brain Tumor Center, Division of Pediatric Neurosurgery, Northwestern University Feinberg School of Medicine, 225 E Chicago Ave, PO Box #28, Chicago, IL, 60611, USA.
authors.forename: Gordan
authors.initials: G
authors.lastname: Grahovac
authors.affiliation: Department of Pathology, Ann & Robert H. Lurie Children's Hospital of Chicago, Northwestern University Feinberg School of Medicine, Chicago, IL, USA.
authors.forename: Veena
authors.initials: V
authors.lastname: Rajaram
authors.affiliation: Department of Pathology, Children's Medical Center, UT Southwestern Medical Center, Dallas, TX, USA.
authors.forename: Nitin
authors.initials: N
authors.lastname: Wadhwani
authors.affiliation: Falk Brain Tumor Center, Division of Pediatric Neurosurgery, Northwestern University Feinberg School of Medicine, 225 E Chicago Ave, PO Box #28, Chicago, IL, 60611, USA.|Development Biology Program, Stanley Manne Children's Research Institute, Ann & Robert H. Lurie Children's Hospital of Chicago, Northwestern University Feinberg School of Medicine, Chicago, IL, USA.
authors.forename: Tatiana
authors.initials: T
authors.lastname: Pundy
authors.affiliation: Department of Biological Sciences, Purdue University Northwest, Hammond, IN, USA.
authors.forename: Barbara
authors.initials: B
authors.lastname: Mania-Farnell
authors.affiliation: Department of Neurological Surgery, Northwestern University Feinberg School of Medicine, Chicago, IL, USA.
authors.forename: Charles David
authors.initials: CD
authors.lastname: James
authors.affiliation: Falk Brain Tumor Center, Division of Pediatric Neurosurgery, Northwestern University Feinberg School of Medicine, 225 E Chicago Ave, PO Box #28, Chicago, IL, 60611, USA. ttomita@luriechildrens.org.|Department of Neurological Surgery, Northwestern University Feinberg School of Medicine, Chicago, IL, USA. ttomita@luriechildrens.org.
authors.forename: Tadanori
authors.initials: T
authors.lastname: Tomita
mesh_terms: D000071916:AC133 Antigen / Q000037:antagonists & inhibitors / Q000378:metabolism*; D018435:ATP Binding Cassette Transporter, Subfamily B / Q000378:metabolism; D000293:Adolescent; D001254:Astrocytoma / Q000188:drug therapy / Q000378:metabolism*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D017024:Chemotherapy, Adjuvant; D002648:Child; D002675:Child, Preschool; D019008:Drug Resistance, Neoplasm; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007223:Infant; D008297:Male; D016328:NF-kappa B / Q000235:genetics; D020360:Neoadjuvant Therapy; D009364:Neoplasm Recurrence, Local / Q000188:drug therapy / Q000378:metabolism*; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics; D051057:Proto-Oncogene Proteins c-akt / Q000235:genetics; D015398:Signal Transduction; D015854:Up-Regulation
chemical_list: C513055:ABCB1 protein, human; D000071916:AC133 Antigen; D018435:ATP Binding Cassette Transporter, Subfamily B; D016328:NF-kappa B; C000606023:PROM1 protein, human; D019869:Phosphatidylinositol 3-Kinases; D051057:Proto-Oncogene Proteins c-akt
keywords: CD133; Chemotherapy; MDR1; Pediatric pilocytic astrocytoma