2014 Oral Presentations
SCIENTIFIC SESSION I: ONCOLOGY
THE NOVEL MDM2 INHIBITOR RG7388 IS HIGHLY EFFECTIVE AGAINST
NEUROBLASTOMA IN VITRO AND IN VIVO
Lakoma A, Barbieri E, McVay M, Chen Z, Agarwal S, Shohet JM, Kim ES, Baylor
College of Medicine
Background
Novel, less toxic therapies for neuroblastoma are urgently needed to improve survival
and reduce treatment related side effects. As neuroblastoma is nearly uniformly p53
wild-type, research has focused on activating innate p53-mediated apoptotic
mechanisms through the inhibition of MDM2, the primary inhibitor of p53. Here we
demonstrate the efficacy of RG7388, a novel MDM2 inhibitor, against p53 wild-type
neuroblastoma in vitro and in vivo orthotopic models of neuroblastoma.
Methods
The human neuroblastoma cell lines, NGP, SH-SY5Y, LAN5 and LAN5si-p53 (p53
silenced by shRNA), were utilized for in vitro and in vivo studies. Cell viability in
response to RG7388 was measured by MTS assay and apoptosis was measured using
a flow cytometric annexin assay. In vivo effect of RG7388 was assessed in an
orthotopic mouse model of neuroblastoma, in which neuroblastoma cells were
intrarenally implanted into 80 female NCr nude mice. The treatment groups received
RG7388 once daily for 14 days (25mg/kg for mice with NGP and SH-SY5Y, and
35mg/kg for mice with LAN5 and LAN5si-p53). At five weeks post-implantation, all mice
were sacrificed, and xenograft tumors resected, weighed and analyzed.
Results
We found a robust decrease in cell proliferation and increase in apoptosis in all p53
wild-type cell lines. The p53 silenced cell line, LAN5si-p53, was found to be resistant to
RG7388. In vivo, RG7388 significantly inhibited tumor growth by 59% in NGP (p=0.003),
67% in SH-SY5Y (p=0.006), and 75% in LAN5 (p=0.0019) xenograft tumors. However,
RG7388 had no inhibitory effect on LAN5 si-p53 xenograft tumors compared to vehicle
treatment (p=0.57). Tumor apoptosis by cleaved caspase-3 staining showed xenografts
treated with RG7388 had significantly increased apoptotic cells in NGP (p<0.0001) and
SH-SY5Y xenografts (p=0.0014).
Conclusion
The MDM2 inhibitor RG7388 significantly inhibits p53 wild-type neuroblastoma tumor
growth, and has no effect on p53-silenced tumors. Our studies suggest RG7388 inhibits
tumor growth by p53-mediated apoptosis.
INCOME AND RACE PREDICT BREAST CANCER CLINICAL STAGE
Z Alawadi, B Nguyen, L Kao, R Wiatrek, T Ko, C Wray, University of Texas- Houston
Background
Racial and ethnic minority breast cancer patients present with advanced pathologic
stage at diagnosis, which may be due to lack of access to care and lower
socioeconomic status (SES). Our hypothesis was that SES accounts for racial
disparities in clinical stage of breast cancer at presentation.
Methods
Retrospective review was performed of breast cancer patients from 10 hospitals in
Harris County, Texas between 2002 and 2011. Demographic and clinical information
was recorded. Clinical stage was calculated based on data from the institutional tumor
registry and electronic medical record. Zip code-based SES data, including mean
household income and percentage of households receiving social support, were
downloaded from www.census.gov. A multivariate ordered logistic regression clustered
by treating facility was used to identify predictors of clinical stage.
Results
Of 3084 breast cancer patients, 1873 were Caucasian (61%), 519 African-Americans
(17%), 353 Hispanics (11%), and 339 Asians (11%). Mean age at diagnosis was 59 ±
14 years. Age, race, mean household income, and percentage of households receiving
social support were predictive of clinical stage at diagnosis (p<0.05). When compared
with Caucasians, African Americans had a lower predicted probability of presenting with
early, clinical stage 1a disease and a higher probability of presenting at stage 4. This
disparity persisted even when comparing opposite ends of the income spectrum.
Caucasians who resided in a median income household at $45k had an equivalent
probability of stage 1a diagnosis as African-Americans who resided in a median income
household of $210k.
Conclusion
Both African-American race and residence in a low SES area contribute to late breast
cancer clinical stage at diagnosis. Addressing factors related to just race or low SES
status alone is unlikely to improve outcomes for African-Americans with low SES.
AMINOOXYACETIC ACID IN COMBINATION WITH OXALIPLATIN DECREASES
COLORECTAL CANCER LIVER METASTASIS
FJ Bohanon, AA Mrazek, LJ Porro, G Im, MR Hellmich, C Chao, University of Texas
Medical Branch
Background
Colorectal cancer (CRC) liver metastasis will develop in ~70% of all patients during the
course of the disease and 40-60% that present with symptomatic CRC will die of
metastasis. Only a minority of patients can undergo liver resection for CRC liver
metastases; most are not surgical candidates or have unresectable disease. Current
chemotherapeutics for Stage IV CRC include treatment with 5-flurouracil combined with
oxaliplatin or irinotecan. Our lab has previously shown that aminooxyacetic acid (AOAA)
inhibits tumor cell metabolism and proliferation both in vitro and in vivo via inhibition of
cystathionine-β-synthase (CBS). The aim of this study is to evaluate whether AOAA
combined with a standard chemotherapeutic such as oxaliplatin (OXA) can decrease
liver metastases in vivo.
Methods
HCT116 cells infected with lentiviral firefly luciferase were orthotopically injected into the
cecum of athymic nude mice. After 24 days post injection, treatment with vehicle,
AOAA, OXA and AOAA+OXA was started (N=6 per group). AOAA was injected
subcutaneously QOD at 9 mg/Kg and OXA was given intraperitoneally weekly at 10
mg/Kg. Bio-luminescence was measured with Xenogen IVIS Spectrum Imaging System
200 to quantify areas of macrometastases. Liver tissues were formalin fixed, parrafinembedded, and stained with hematoxylin and eosin. Liver metastases were visually
counted on a Nikon Eclipse E600 microscope at 400X magnification with an average of
30 high-powered fields per slide and quantified using a weighted scale based on the
number of cells within each metastatic focus.
Results
Luciferase intensity using IVIS did not show statistical significance between the groups
(p=0.292). To measure micrometastatic disease, we counted liver metastases and
demonstrate a significant difference between the AOAA+OXA group compared to the
control (p=0.024)
Conclusion
Combined treatment with OXA and AOAA significantly decreases CRC liver
metastases. Future studies are underway to study the role of AOAA in metastatic CRC.