Changed adhesion molecule profile of Ewing tumor cell lines and xenografts under the influence of ionizing radiation.
BACKGROUND
Adhesion molecules are involved in cell-cell and cell-matrix interactions and may be informative to characterize intercellular mechanisms of invasion and metastasis. This study was performed to characterize radiation-induced changes in the adhesion molecule profile of Ewing tumor subpopulations on a single cell level.


METHODS
In the present study, two Ewing tumors were characterized in vitro 4, 24 and 72 hours after radiation with 5 Gy and in vivo in a xenograft model 4, 6 and 15 days after radiation with 30 Gy, together with non-irradiated controls, by five parameter flow cytometry. Directly fluorescence-conjugated antibodies that were directed against adhesion molecules (LFA-1 (CD11a), HCAM (CD44), VLA-2 (CD49b), ICAM-1 (CD54), NCAM (CD56), LECAM-1 (CD62L) and CD86) were used. Annexin V and 7-AAD were used to characterize radiation-induced apoptosis.


RESULTS
Tumor cell subpopulations were identified by the expression of adhesion molecules, apoptotic markers and DNA content. Heterogeneous changes of the adhesion molecule profile were identified on tumor cell subpopulations after radiation. The expression of CD11a and CD62L correlated with the expression of apoptosis-associated markers.


CONCLUSIONS
The changes of flow cytometric profile under radiation may potentially correlate with a changed metastatic potential of tumor cell subpopulations.
Department of Radiotherapy, University Hospital Münster, Albert-Schweitzer-Str. 33, 48149 Münster, Germany. stkoene@uni-muenster.de
Stefan
S
Könemann
Johann
J
Malath
Tobias
T
Bölling
Astrid
A
Kolkmeyer
Kirsten
K
Janke
Dorothea
D
Riesenbeck
Stefan
S
Hesselmann
Tan Phu
TP
Nguyen
Raihanatou
R
Diallo
Josef
J
Vormoor
Normann
N
Willich
Andreas
A
Schuck
D000818:Animals; D015703:Antigens, CD / Q000096:biosynthesis / Q000528:radiation effects; D017209:Apoptosis / Q000502:physiology / Q000528:radiation effects; D015815:Cell Adhesion Molecules / Q000096:biosynthesis* / Q000528:radiation effects*; D045744:Cell Line, Tumor; D005434:Flow Cytometry; D019085:Fluorescent Antibody Technique, Direct; D006801:Humans; D051379:Mice; D008819:Mice, Nude; D012512:Sarcoma, Ewing / Q000378:metabolism* / Q000473:pathology / Q000532:radiotherapy*; D013997:Time Factors; D015854:Up-Regulation / Q000528:radiation effects; D023041:Xenograft Model Antitumor Assays
D015703:Antigens, CD; D015815:Cell Adhesion Molecules