Page 262 - 2014 Printable Abstract Book
P. 262
increased by radiation therapy. Methods: We established cultures of GSC from five patients. We first
performed spreading assays on differents substrates and then directional migration assays on laminin-
111. We studied expression of α6β1 integrin with RT-PCR and flow cytometry and its role in spreading
with blocking antibodies. These experiments were then performed after irradiation (6Gy).
Results: We found that among extracellular matrix proteins found in basal membrane of tumorigenic
vessels, laminin-111 is the common spreading substrate for GSC and acts as a specific chemoattractant.
This migration is mediated by α6β1 integrin, one of the receptor of laminin-111. Moreover, we reported
that ionizing radiation rapidly induced GSC spreading in a α6β1 integrin-dependent manner. Conclusion:
Our results demonstrate that GSC migration properties are modified by ionizing radiation via α6β1 integrin
which can be an interesting target to decrease the risk of tumor relapse after radio-chemotherapy.
(PS4-45) The combinational effects of gamma secretase inhibition and radiation on stem cells. Yazeed
M. Alhiyari, MS; Erina Vlashi, PhD; Patricia Frohnen, BS; Maha Kazmi; and Frank Pajonk, PhD, UCLA, Los
Angeles, CA
Gamma secretase (GS) is an intramembraneous protease that cleaves over 91 different
membrane substrates. GS is responsible for the final S3 cleavage of the notch receptor, thereby releasing
the notch intracellular domain (NICD) into the cytoplasm. Upon translocation into the nucleus NICD
activates the transcription of notch effector proteins that maintain stemness. Due to GS activity on the
notch pathway, it has become an attractive target for cancer stem cells. The cancer stem cell (CSC)
hypothesis states that cancers are generated and maintained by a group of cells that share similarities
with normal adult stem cells. CSCs have been shown to be resistant to most current anti-cancer treatment
approaches, including radiation therapy, thus contributing to tumor repopulation after therapy. A
combinational therapy that targets both cancer cells and inhibits cancer stem cell growth is highly
desirable. Unfortunately, there is inconsistent data determining the combinational effects of GS inhibitors
(GSI) with radiation. The goal of this study was to evaluate the efficacy of GSI treatment with radiation
therapy in reducing the cancer stem cell population in glioblastoma multiforme (GBM). Utilizing a panel
of GBM cell lines varying in PTEN, p53, and EGFR status, we evaluated the effects of GSI plus radiation
treatment on the cancer stem cell population, using sphere-forming capacity assays, cell cycle analysis,
and γH2AX and PI/PY staining. Our data demonstrates that PTEN status plays a role in the sensitivity to
GSI treatment. In addition, we observed that treating PTEN-wt cell lines with GSI improved survival among
the stem cell population while PTEN-mutant lines showed a reduce survival. Furthermore, GSI treatment
alters the cell cycle kinetics for the PTEN-mutant cell lines while PTEN-wt remain largely unchanged. In
conclusion, the effect of GSI plus radiation suggests a possible link to cell survival though DNA repair
pathways.
(PS4-46) Trp53 dependent clonal expansion of airway epithelial progenitor cells following high-LET
1
1
2
radiation exposure. Alicia M. Farin ; Nicholas D. Manzo ; and Barry R. Stripp, Cedars-Sinai Medical
1
Center, Los Angeles, CA and University of North Carolina at Chapel Hill, Chapel Hill, NC
2
The mammalian airway is lined with an epithelium that is maintained by regionally distinct
progenitor cells. In the distal conducting airway of the mouse, CCSP-expressing Club cells are the primary
progenitor cells responsible for normal epithelial maintenance and repair. Exposure of the epithelium to
260 | P a g e
performed spreading assays on differents substrates and then directional migration assays on laminin-
111. We studied expression of α6β1 integrin with RT-PCR and flow cytometry and its role in spreading
with blocking antibodies. These experiments were then performed after irradiation (6Gy).
Results: We found that among extracellular matrix proteins found in basal membrane of tumorigenic
vessels, laminin-111 is the common spreading substrate for GSC and acts as a specific chemoattractant.
This migration is mediated by α6β1 integrin, one of the receptor of laminin-111. Moreover, we reported
that ionizing radiation rapidly induced GSC spreading in a α6β1 integrin-dependent manner. Conclusion:
Our results demonstrate that GSC migration properties are modified by ionizing radiation via α6β1 integrin
which can be an interesting target to decrease the risk of tumor relapse after radio-chemotherapy.
(PS4-45) The combinational effects of gamma secretase inhibition and radiation on stem cells. Yazeed
M. Alhiyari, MS; Erina Vlashi, PhD; Patricia Frohnen, BS; Maha Kazmi; and Frank Pajonk, PhD, UCLA, Los
Angeles, CA
Gamma secretase (GS) is an intramembraneous protease that cleaves over 91 different
membrane substrates. GS is responsible for the final S3 cleavage of the notch receptor, thereby releasing
the notch intracellular domain (NICD) into the cytoplasm. Upon translocation into the nucleus NICD
activates the transcription of notch effector proteins that maintain stemness. Due to GS activity on the
notch pathway, it has become an attractive target for cancer stem cells. The cancer stem cell (CSC)
hypothesis states that cancers are generated and maintained by a group of cells that share similarities
with normal adult stem cells. CSCs have been shown to be resistant to most current anti-cancer treatment
approaches, including radiation therapy, thus contributing to tumor repopulation after therapy. A
combinational therapy that targets both cancer cells and inhibits cancer stem cell growth is highly
desirable. Unfortunately, there is inconsistent data determining the combinational effects of GS inhibitors
(GSI) with radiation. The goal of this study was to evaluate the efficacy of GSI treatment with radiation
therapy in reducing the cancer stem cell population in glioblastoma multiforme (GBM). Utilizing a panel
of GBM cell lines varying in PTEN, p53, and EGFR status, we evaluated the effects of GSI plus radiation
treatment on the cancer stem cell population, using sphere-forming capacity assays, cell cycle analysis,
and γH2AX and PI/PY staining. Our data demonstrates that PTEN status plays a role in the sensitivity to
GSI treatment. In addition, we observed that treating PTEN-wt cell lines with GSI improved survival among
the stem cell population while PTEN-mutant lines showed a reduce survival. Furthermore, GSI treatment
alters the cell cycle kinetics for the PTEN-mutant cell lines while PTEN-wt remain largely unchanged. In
conclusion, the effect of GSI plus radiation suggests a possible link to cell survival though DNA repair
pathways.
(PS4-46) Trp53 dependent clonal expansion of airway epithelial progenitor cells following high-LET
1
1
2
radiation exposure. Alicia M. Farin ; Nicholas D. Manzo ; and Barry R. Stripp, Cedars-Sinai Medical
1
Center, Los Angeles, CA and University of North Carolina at Chapel Hill, Chapel Hill, NC
2
The mammalian airway is lined with an epithelium that is maintained by regionally distinct
progenitor cells. In the distal conducting airway of the mouse, CCSP-expressing Club cells are the primary
progenitor cells responsible for normal epithelial maintenance and repair. Exposure of the epithelium to
260 | P a g e
