Articles by Valerie P. Opipari in JoVE
Utilization of Ultrasound Guided Tissue-directed Cellular Implantation for the Establishment of Biologically Relevant Metastatic Tumor Xenografts Tina T. Thomas1, Sahiti Chukkapalli1, Raelene A. Van Noord1, Melanie Krook2, Mark J. Hoenerhoff3, Jonathan R. Dillman4, Elizabeth R. Lawlor2,5, Valerie P. Opipari5, Erika A. Newman1 1Departments of Surgery, C.S Mott Children's and Women's Hospital, The University of Michigan Medical School, 2Departments of Pathology, C.S Mott Children's and Women's Hospital, The University of Michigan Medical School, 3Unit for Laboratory Animal Medicine, The University of Michigan Medical School, 4Departments of Radiology, C.S Mott Children's and Women's Hospital, The University of Michigan Medical School, 5Departments of Pediatrics, C.S Mott Children's and Women's Hospital, The University of Michigan Medical School Here, we present a protocol to utilize ultrasound-guided injection of neuroblastoma (NB) and Ewing's sarcoma (ES) cells (established cell lines and patient-derived tumor cells) at biologically relevant sites to create reliable preclinical models for cancer research.
Other articles by Valerie P. Opipari on PubMed
Alternative NHEJ Pathway Proteins As Components of MYCN Oncogenic Activity in Human Neural Crest Stem Cell Differentiation: Implications for Neuroblastoma Initiation Cell Death & Disease. | Pubmed ID: 29238067 Neuroblastoma is a cancer of neural crest stem cell (NCSC) lineage. Signaling pathways that regulate NCSC differentiation have been implicated in neuroblastoma tumorigenesis. This is exemplified by MYCN oncogene targets that balance proliferation, differentiation, and cell death similarly in normal NCSC and in high-risk neuroblastoma. Our previous work discovered a survival mechanism by which MYCN-amplified neuroblastoma circumvents cell death by upregulating components of the error-prone non-canonical alternative nonhomologous end-joining (alt-NHEJ) DNA repair pathway. Similar to proliferating stem cells, high-risk neuroblastoma cells have enhanced DNA repair capacity, overcoming DNA damage with higher repair efficiency than somatic cells. Adequate DNA maintenance is required for lineage protection as stem cells proliferate and during tumor progression to overcome oncogene-induced replication stress. On this basis, we hypothesized that alt-NHEJ overexpression in neuroblastoma is a cancer cell survival mechanism that originates from DNA repair systems of NCSC, the presumed progenitor cell of origin. A human NCSC model was generated in which inducible MYCN triggered an immortalized phenotype capable of forming metastatic neuroectodermal tumors in mice, resembling human neuroblastoma. Critical alt-NHEJ components (DNA Ligase III, DNA Ligase I, and Poly [ADP-ribose polymerase 1]) were highly expressed in normal early NCSC, and decreased as cells became terminally differentiated. Constitutive MYCN expression maintained high alt-NHEJ protein expression, preserving the expression pattern of the immature neural phenotype. siRNA knockdown of alt-NHEJ components reversed MYCN effects on NCSC proliferation, invasion, and migration. DNA Ligase III, Ligase I, and PARP1 silencing significantly decreased neuroblastoma markers expression (TH, Phox2b, and TRKB). These results utilized the first human NCSC model of neuroblastoma to uncover an important link between MYCN and alt-NHEJ expression in developmental tumor initiation, setting precedence to investigate alt-NHEJ repair mechanics in neuroblastoma DNA maintenance.
Tissue-directed Implantation Using Ultrasound Visualization for Development of Biologically Relevant Metastatic Tumor Xenografts In Vivo (Athens, Greece). Sep-Oct, 2017 | Pubmed ID: 28882943 Advances in cancer therapeutics depend on reliable in vivo model systems. To develop biologically relevant xenografts, ultrasound was utilized for tissue-directed implantation of neuroblastoma (NB) cell line and patient-derived tumors in the adrenal gland, and for renal subcapsular engraftment of Ewing's sarcoma (ES).