Page 202 - 2014 Printable Abstract Book
P. 202
(PS3-22) Effects of IDH1 mutation and inhibition on radiation sensitivity. Aparna H. Kesarwala, MD, PhD;
Sarani Ghoshal, PhD; William DeGraff, MS; John A. Cook, PhD; and James B. Mitchell, PhD; National Cancer
Institute, Bethesda, MD
Mutations in cytoplasmic isocitrate dehydrogenase (IDH1) have been identified in multiple types
of human cancers, including gliomas, lung adenocarcinomas, acute lymphoblastic leukemias, thyroid
carcinomas, and intrahepatic cholangiocarcinomas. As many as 70% of glioblastoma patients possess the
most common mutation, IDH1 R132H. Multiple clinical investigations have demonstrated that IDH1
mutational status correlates with patient outcomes, with IDH1-mutated patients showing improved
responses to chemotherapy and radiation. We investigated the effects of IDH1 mutation and inhibition
WT
on radiation sensitivity. Wild-type (U87) human glioblastoma cells and wild-type (HCT116 ) and IDH1
MT
R132H mutant (HCT116 ) human colorectal cancer cells were exposed to 0-100 µM temozolomide or 0-
1000 nM IDH1 inhibitor AGI5189 for 1 or 24 hours either prior to or following up to 10 Gy radiation.
Survival was assessed by clonogenic assay and dose modifying factors (DMF) were calculated at 10%
survival from radiation survival curves. U87 glioblastoma cells and HCT116 WT colorectal cells expressed
only wild-type IDH1, while HCT116 MT cells expressed both wild-type and the R132H mutant of IDH1.
Temozolomide did not affect cell survival, while the maximum cytotoxicity of 1000 µM AGI5189 was 20%
at 24 hours to U87 cells. AGI5189 pre-treatment of U87 cells resulted in a 50% decrease in survival
following single-dose radiation. Neither pre- nor post-treatment of HCT116 WT or HCT116 MT cells with
AGI5189 resulted in modification of radiosensitivity. Likewise, no modification of radiosensitivity was
observed in HCT116 or HCT116 cells pre-treated with temozolomide. Thus, the IDH1 R132H mutation
MT
WT
had no effect on the inherent radiosensitivity of colorectal cancer cells in culture. IDH1 inhibition also did
not significantly enhance radiosensitivity in either wild-type or IDH1 mutant cancer cells. Additional
clonogenic survival data and metabolic analysis of cells in the presence and absence of IDH1 inhibition will
be presented.
(PS3-23) Pudendal nerve and internal pudendal artery damage may contribute to radiation-induced
2
1
3
erectile dysfunction. Michael W. Nolan, DVM, Ph,D ; Angela J. Marolf, DVM ; E.J. Ehrhart, DVM, Ph.D ;
3
5
4
Susan L. Kraft, DVM, Ph.D ; Stephanie Engel, DVM, MS ; L.R. Whalen, DVM, Ph.D ; Hiroto Yoshikawa, DVM,
3
3
6
3
Ph.D ; Anne E. Golden, CVT ; Todd H. Wasserman, MD ; Susan M. LaRue, DVM, Ph.D
1
North Carolina State University, Raleigh, NC ; Colorado State University Department of Environmental and
2
Radiological Health Sciences, Fort Collins, CO ; Colorado State University Flint Animal Cancer Center, Fort
4
3
Collins, CO ; Colorado State University Department of Clinical Sciences, Fort Collins, CO ; Colorado State
5
University Department of Biomedical Sciences, Fort Collins, CO ; and Washington University, St. Louis,
6
MO
Purpose/Objectives: Erectile dysfunction occurs in 36-59% of men treated with radiation therapy
for prostate cancer, and yet the etiopathology of radiation-induced erectile dysfunction (RI-ED) remains
poorly understood. A novel animal model has recently been described to facilitate study of RI-ED, wherein
stereotactic body radiotherapy (SBRT) is used to irradiate the prostate, posterolateral prostatic
neurovascular bundles (NVB), and penile bulb (PB) of dogs. The purpose of these studies were to describe
200 | P a g e
Sarani Ghoshal, PhD; William DeGraff, MS; John A. Cook, PhD; and James B. Mitchell, PhD; National Cancer
Institute, Bethesda, MD
Mutations in cytoplasmic isocitrate dehydrogenase (IDH1) have been identified in multiple types
of human cancers, including gliomas, lung adenocarcinomas, acute lymphoblastic leukemias, thyroid
carcinomas, and intrahepatic cholangiocarcinomas. As many as 70% of glioblastoma patients possess the
most common mutation, IDH1 R132H. Multiple clinical investigations have demonstrated that IDH1
mutational status correlates with patient outcomes, with IDH1-mutated patients showing improved
responses to chemotherapy and radiation. We investigated the effects of IDH1 mutation and inhibition
WT
on radiation sensitivity. Wild-type (U87) human glioblastoma cells and wild-type (HCT116 ) and IDH1
MT
R132H mutant (HCT116 ) human colorectal cancer cells were exposed to 0-100 µM temozolomide or 0-
1000 nM IDH1 inhibitor AGI5189 for 1 or 24 hours either prior to or following up to 10 Gy radiation.
Survival was assessed by clonogenic assay and dose modifying factors (DMF) were calculated at 10%
survival from radiation survival curves. U87 glioblastoma cells and HCT116 WT colorectal cells expressed
only wild-type IDH1, while HCT116 MT cells expressed both wild-type and the R132H mutant of IDH1.
Temozolomide did not affect cell survival, while the maximum cytotoxicity of 1000 µM AGI5189 was 20%
at 24 hours to U87 cells. AGI5189 pre-treatment of U87 cells resulted in a 50% decrease in survival
following single-dose radiation. Neither pre- nor post-treatment of HCT116 WT or HCT116 MT cells with
AGI5189 resulted in modification of radiosensitivity. Likewise, no modification of radiosensitivity was
observed in HCT116 or HCT116 cells pre-treated with temozolomide. Thus, the IDH1 R132H mutation
MT
WT
had no effect on the inherent radiosensitivity of colorectal cancer cells in culture. IDH1 inhibition also did
not significantly enhance radiosensitivity in either wild-type or IDH1 mutant cancer cells. Additional
clonogenic survival data and metabolic analysis of cells in the presence and absence of IDH1 inhibition will
be presented.
(PS3-23) Pudendal nerve and internal pudendal artery damage may contribute to radiation-induced
2
1
3
erectile dysfunction. Michael W. Nolan, DVM, Ph,D ; Angela J. Marolf, DVM ; E.J. Ehrhart, DVM, Ph.D ;
3
5
4
Susan L. Kraft, DVM, Ph.D ; Stephanie Engel, DVM, MS ; L.R. Whalen, DVM, Ph.D ; Hiroto Yoshikawa, DVM,
3
3
6
3
Ph.D ; Anne E. Golden, CVT ; Todd H. Wasserman, MD ; Susan M. LaRue, DVM, Ph.D
1
North Carolina State University, Raleigh, NC ; Colorado State University Department of Environmental and
2
Radiological Health Sciences, Fort Collins, CO ; Colorado State University Flint Animal Cancer Center, Fort
4
3
Collins, CO ; Colorado State University Department of Clinical Sciences, Fort Collins, CO ; Colorado State
5
University Department of Biomedical Sciences, Fort Collins, CO ; and Washington University, St. Louis,
6
MO
Purpose/Objectives: Erectile dysfunction occurs in 36-59% of men treated with radiation therapy
for prostate cancer, and yet the etiopathology of radiation-induced erectile dysfunction (RI-ED) remains
poorly understood. A novel animal model has recently been described to facilitate study of RI-ED, wherein
stereotactic body radiotherapy (SBRT) is used to irradiate the prostate, posterolateral prostatic
neurovascular bundles (NVB), and penile bulb (PB) of dogs. The purpose of these studies were to describe
200 | P a g e
