ESTRO 36 Abstract Book

S544

ESTRO 36

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apoptosis (Annexin V and propidium iodin PI) 3/ Cell cycle

modifications (PI)

Results

Our results showed that IR on RCCL not expressing HLA-G,

ILT2 or ILT4 did not induce these molecules. However, in

constitutively expressing HLA-G or ILT4 RCCL, IR

decreased significantly HLA-G and ILT4 expression.

Furthermore, we found that HLA-G, ILT2 and ILT4

transduction increased radioresistance. This effect was

partially aborted by the use of antibodies directed against

these molecules. Mechanisms of radio resistance are under

investigations and will be presented at the meeting.

Conclusion

Ionizing radiation decreases the expression of HLA-G or its

receptors in RCCL constitutively expressing these

molecules. HLA-G and its ligands increase radioresistance.

This finding could have some clinical implications for

stereotactic radiotherapy of renal cancer or its

metastasis.

PO-0985 Tumor metabolic changes after neoadjuvant

radiotherapy: consequences for surgery-related

metastases

N. Leroi

, F. Lallemand

, J. Leenders

, S. Blacher

, P. De

Tullio

, P. Coucke

, A. Noel

, P. Martinive

C.H.U. Liège - Université de Liège, Radiotherapy Dept-

Laboratoire de Biologie des Tumeurs et du

Développement, Liège, Belgium

C.H.U. Liège - Université de Liège, Radiotherapy Dept-

Research center of Cyclotron, Liège, Belgium

Université de Liège, CIRM- Chimie Pharmaceutique,

Liège, Belgium

Université de Liège, Laboratoire de Biologie des

Tumeurs et du Développement, Liège, Belgium

C.H.U. Liège - Université de Liège, Radiotherapy Dept.,

Liège, Belgium

Purpose or Objective

Neoadjuvant radiotherapy (NeoRT) aims at improving

tumor local control and patient overall survival. In the

case of locally advanced rectal cancer, NeoRT increases

significantly local control compared to surgery alone, but

patient overall survival is not improved. Currently,

predicting tumor response and recurrences represent a

major challenge for personalized medicine. Previously, we

developed a pre-clinical model of NeoRT and showed that

the timing of surgery and NeoRT schedules both influenced

metastasis burden (Leroi et al., Oncotarget, 2015). Based

on this model, we study the impact of RT schedule on the

primary tumor metabolome at the time of surgery to

predict local recurrence and metastatic profile.

Material and Methods

We locally irradiated primary tumors (MDA-MB231 cells

and 4T1 cells), subcutaneously implanted to SCID and

BalbC mice, with two NeoRT schedules (5x2Gy and 2x5Gy).

We surgically removed tumors 4 or 11 days after the end

of RT and kept the mice alive for the metastatic growth.

Non-irradiated control tumors were also surgically

collected at the same time. For metabolomic study, tumor

samples were homogenized in deuterated phosphate

buffer and supplemented with maleic acid and TMSP

before Nuclear Magnetic Resonance (NMR) analyses. Data

were analyzed with powerful statistical tool (supervised

and multivariate analyses).

Results

Irradiated 4T1 and MDA-MB231 tumors displayed different

metabolic profile than non-irradiated tumors, especially 4

days after the end of RT for 4T1 tumors and 11 days after

NeoRT for MDA-MB231 tumors. Moreover, we observed a

decrease in some metabolite levels (i.e. glutamate,

taurine, glycine, myoinositol) in tumors following both

NeoRT schedules. We also noticed an increase in general

lipid signals in irradiated MDA-MB231 tumors. This was not

related to adipocyte infiltration, as we observed, by

immunostaining, decreased infiltration of perilipin and

FABP4+ cells in these tumors following NeoRT. Preliminary

results with OPLS-DA analyses showed discrimination of

primary tumor metabolome according to the propensity to

induce loco-regional recurrence (significant for tumors

collected 4 days after 5x2Gy). Furthermore, based on the

metabolic profile of the primary MDA-MB231 tumors and

OPLS linear regression, mathematical models were

established in the different groups allowing to predict the

metastatic burden (r²=0,80-0,90).

Conclusion

In preclinical models, we show profound modifications of

the primary tumor metabolome following NeoRT through

NMR analyses, offering new opportunities to understand

tumor metabolism adaptation following NeoRT.

Furthermore, others NMR results appear very relevant

when transposed to clinic. Indeed, with mathematical

models, local recurrence and metastatic profiles were

predictable based on the metabolomic profile of the

primary tumor at the time of surgery, which could be

helpful to adapt adjuvant therapies in order to prevent

relapse.

PO-0986 Downregulation of the oncoprotein SET

enhances RT-induced apoptosis in hepatocellular

carcinoma

C.Y. Huang

, M.H. Hung

, C.W. Kuo

, C.T. Shih

, M.H.

Chen

, K.F. Chen

National Taiwan university hospital, Division of

Radiation Oncology- Department of Oncology, Taipei,

Taiwan

Taipei Veterans General Hospital, Division of Medical

Oncology- Department of Oncology, Taipei, Taiwan

Yuanpei University of Medical Technology, Department

of Medical Imaging and Radiological Technology,

Hsinchu, Taiwan

National Yang-Ming University, Institute of

Biopharmaceutical Sciences, Taipei, Taiwan

National Taiwan university hospital, Department of

Medical Research, Taipei, Taiwan

Purpose or Objective

Hepatocellular carcinoma (HCC) is among the most lethal

human malignancies worldwide. Radiotherapy (RT) is not

commonly used to treat HCC with regard to both

suboptimal treatment efficacy and toxicity. The current

project aimed to characterize the role of a novel

oncoprotein SET/ I2PP2A (Inhibitor-2 of protein

phosphatase 2A) in mediating the radio-resistance of HCC

cell and explore the potential on antagonizing SET to

improve the anti-HCC effects of RT.

Material and Methods

The effects of RT in HCC cells with different expression of

SET were assessed by colony formation and sphere

formation assay. We generated a novel SET antagonist,

EMQA

-(3-ethynylphenyl)-6,7-dimethoxy-N

-(4-

phenoxyphenyl) quinazoline-2,4-diamine), to validate the

therapeutic potential of targeting SET. The combination

effects of EMQA and RT were tested in vitro using four

different HCC cell lines, Hep3B, PLC5, HA22T and HA59T,

and a subcutaneous PLC5 xenografted model in vivo. HCC

cells were exposed to 1 fraction of 4-Gy radiation using a

cobalt 60 unit (at a dose rate of 0.5 Gy/min) with the

source-axis-distance set at 80 cm to the bottom of the

dish. After 48 hours, the cells were treated with or

without EMQA.

Results

To explore the roles of SET in affecting the radio-

sensitivity in HCC, we first generated PLC5 and Hep3B

cells with different SET activity, and assessed the effects

of RT on these cells by colony formation and tumor sphere

assay. Comparing to mock-treated cells, HCC cells

transfected with shRNA against SET were shown with

significant reduced viability under the same RT treatment.

Oppositely, cells with ectopic expression of SET were more

resistant to RT. Next, we used EMQA to test whether