ESTRO 2024 - Abstract Book

S5384

Radiobiology - Tumour biology

ESTRO 2024

Results:

A preliminary analysis was performed on the ability of OVSAHO, OVCAR8 and OVCAR3 cells to form colonies under the different experimental conditions tested. The curves in Figure 1 represent the clonogenic survival fractions of each cell line according to the dose of XRT or CIRT administered. A higher significant radio-cytotoxicity was observed in CIRT conditions for each cell line ( p < 0.05). OVCAR3 was more radioresistant to XRT compared to OVCAR8 and OVSAHO with the latter being the most radiosensitive for each dose. When exposed to high LET, OVSAHO and OVCAR8 cells showed different patterns of response to CIRT suggesting that OVSAHO cells are more sensitive to CIRT than OVCAR8. However, both for OVCAR8 and OVSAHO there was a significant reduction in the clonogenic survival up to 4 Gy (p= 0.001 at 2 and 3 Gy; p = 0.0018 at 4 Gy). Moreover, for highly XRT-radioresistant OVCAR3, the number of colonies dramatically decreased after CIRT ( p= 0.0012 at 1 Gy; p = 0.0001 from 2 to 5 Gy).

Figure 1: Clonogenic survival curves for each condition of irradiation

Conclusion:

According to clinical data, BRCA mutation is a pattern of radiosensitivity even in the presence of p53 mutation. The wild-type status of BRCA is associated with a significant XRT-radioresistance that can be overcome by the high LET. In the presence of other radioresistant hallmarks (KRAS and ERBB2), the methylation of BRCA1 seemed to lose its intrinsic radiosensitivity. Migration and Invasiveness analysis are needed to complete the radiobiological characterisations of these challenging cell lines.

Keywords: Low LET, High LET, Ovarian Cancer

1779

Mini-Oral

Genomic instability due to chromatin deregulation in SPOP-deficient prostate cancer cells

Shaimaa Fahmy 1 , Hannah Voß 2 , Alexandra Zielinski 1 , Alicia Eckhardt 1,3 , Nina Struve 1,4 , Christoph Oing 5,4 , Hartmut Schlüter 2 , Ulrich Schüller 3 , Cordula Petersen 1 , Kai Rothkamm 1 , Wael Y Mansour 1,4