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

Abstract

Radiotherapy is a powerful cure for several types of solid tumours, but its application is often limited because of severe side effects in individual patients. With the aim to find biomarkers capable of predicting normal tissue side reactions we analysed the radiation responses of cells from individual head and neck tumour and breast cancer patients of different clinical radiosensitivity in a multicentric study. Multiple parameters of cellular radiosensitivity were analysed in coded samples of peripheral blood lymphocytes (PBLs) and derived lymphoblastoid cell lines (LCLs) from 15 clinical radio-hypersensitive tumour patients and compared to age- and sex-matched non-radiosensitive patient controls and 15 lymphoblastoid cell lines from age- and sex- matched healthy controls of the KORA study. Experimental parameters included ionizing radiation (IR)-induced cell death (AnnexinV), induction and repair of DNA strand breaks (Comet assay), induction of yH2AX foci (as a result of DNA double strand breaks), and whole genome expression analyses. Considerable inter-individual differences in IR-induced DNA strand breaks and their repair and/or cell death could be detected in primary and immortalised cells with the applied assays. The group of clinically radiosensitive patients was not unequivocally distinguishable from normal responding patients nor were individual overreacting patients in the test system unambiguously identified by two different laboratories. Thus, the in vitro test systems investigated here seem not to be appropriate for a general prediction of clinical reactions during or after radiotherapy due to the experimental variability compared to the small effect of radiation sensitivity. Genome-wide expression analysis however revealed a set of 67 marker genes which were differentially induced 6 h after in vitro-irradiation in lymphocytes from radio-hypersensitive and non-radiosensitive patients. These results warrant future validation in larger cohorts in order to determine parameters potentially predictive for clinical radiosensitivity.

The harmonization process to set up and maintain an operational biological and physical retrospective dosimetry network: QA QM applied to the RENEB network

“…There are a considerable number of publications with challenging or even contradictory information about the applicability and use of apparently well-established biomarkers (Greve et al 2012). Even for relatively well-established assays such as the MN assay, the predictive potential of these assays is still in question (Djuzenova et al 2006).…”

Naujas požiūris į onkologinių ligonių spindulinį gydymą – individualaus radiojautrio tyrimas

“…Nauja tendencija analizuojant citogenetinių mokslo tyrimų rezultatus parodė, kad pacientų genetiniai veiksniai nulemia individualų jautrį jonizuojančiai spinduliuotei [1,2]. Biologinis jonizuojančiosios spinduliuotės poveikis vyksta tiesioginiu ir netiesioginiu būdu.…”

“…Šalutinis piktybinių navikų spindulinio gydymo poveikis, kuris pasireiškia dėl ląstelių DNR pažeidimo, riboja paskirtosios suminės dozės navikui dydį [3].Didesnis jautrumas jonizuojančiajai spinduliuotei yra onkologinių ligų rizikos veiksnys. Nustatyta, kad pacientams, kurie jautresni jonizuojančiai spinduliuotei, po skirto spindulinio gydymo dažniau indukuojami antriniai piktybiniai navikai [2,3]. Tai įvyksta dėl struktūrinių chromosomų pažaidų sąlygoto proto -onkogenų aktyvavimo bei naviko -supresorių genų eliminavimo, kas sąlygoja tumorogenezę [4].…”

“…Mokslo tyrimų rezultatais įrodyta, kad jonizuojančios spinduliuotės paveiktų kraujo limfocitų apoptozėje, nekrozėje skaičiavimas neatspindi individualaus klinikinio radiojautrio [2]. Pasitelkiant citogenetinius metodus -sustabdytos citokinezės mikrobranduolių analizės ir G2 metodus galima identifikuoti jautrius jonizuojančiai spinduliuotei asmenis [3].…”

Usefulness of Saliva Samples for Biomarker Studies in Radiation Research

“…These biomarkers include for instance gene expression profiling (42) and single gene expression (43), 8-oxo-dG oxidative stress biomarker (44), gH2AX induction and loss (45), and lymphocyte apoptosis combined to specific SNPs (46). Validating those biomarkers in saliva or buccal cell samples would be of great interest, not only to facilitate the screening of radiosensitive patients to adapt their treatment and decrease the total dose received, but also for recruitment and/or identification of radiosensitive subjects into epidemiologic studies.…”