Multicentric investigation of ionising radiation-induced cell death as a predictive parameter of individual radiosensitivity

Abstract

In the present study, the predictive value of ionising radiation (IR)-induced cell death was tested in peripheral blood lymphocytes (PBLs) and their corresponding Epstein-Barr virus-transformed lymphoblastoid cell lines (LCLs) in an interlaboratory comparison. PBLs and their corresponding LCLs were derived from 15 tumour patients, that were considered clinically radiosensitive based on acute side-effects, and matched controls. Upon coding of the samples, radiosensitivity of the matched pairs was analysed in parallel in three different laboratories by assessing radiation-induced apoptotic and necrotic cell death using annexin V. All participating laboratories detected a dose-dependent increase of apoptosis and necrosis in the individual samples, to a very similar extent. However, comparing the mean values of apoptotic and necrotic levels derived from PBLs of the radiosensitive cohort with the mean values of the control cohort did not reveal a significant difference. Furthermore, within 15 matched pairs, no sample was unambiguously and independently identified by all three participating laboratories to demonstrate in vitro hypersensitivity that matched the clinical hypersensitivity. As has been reported previously, apoptotic and necrotic cell death is barely detectable in immortalised LCL derivatives using low doses of IR. Concomitantly, the differences in apoptosis or necrosis levels found in primary cells of different individuals were not observed in the corresponding LCL derivatives. All participating laboratories concordantly reasoned that, with the methods applied here, IR-induced cell death in PBLs is unsuitable to unequivocally predict the individual clinical radiosensitivity of cancer patients. Furthermore, LCLs do not reflect the physiological properties of the corresponding primary blood lymphocytes with regard to IR-induced cell death. Their value to predict clinical radiosensitivity is thus highly questionable.

Evaluation of Different Biomarkers to Predict Individual Radiosensitivity in an Inter-Laboratory Comparison–Lessons for Future Studies

“…As has been reported previously, the Annexin V/PI assay failed to detect Annexin V-positive and Annexin V/PI-double-positive cells in immortalised lymphoblastoid cell lines (LCL) upon irradiation with low doses of IR [12]. The differences in IR-induced apoptosis found in primary cells of different individuals were thus not detectable in the corresponding LCL derivatives and all statistic evaluations are based on PBL results.…”

“…Their value to predict clinical radiosensitivity is thus highly questionable [12]. This notion is strongly supported by the gene expression data.…”

“…Blood samples (250 ml each) for this study were collected from these 30 patients two to five years following radiotherapy, including an evaluation of late reactions. Sample preparation and management as well as EBV-transformation were described previously [12].…”

“…All test- and measuring parameters were standardised between the participating laboratories; in detail the whole procedure has been described recently [12].…”

Influence of secreted frizzled receptor protein 1 (SFRP1) on neoadjuvant chemotherapy in triple negative breast cancer does not rely on WNT signaling

“…Flow cytometric cell analysis and quantification of cell death took place on a flow cytometer (CyFlow Space, Partec, Germany) as described previously [46,47]. …”