Nathalie van den Tempel1, Hanny Odijk1, Netteke van Holthe2, Kishan Naipal1, Anja Raams1, Berina Eppink1, Dik C van Gent1, Jose Hardillo3, Gerda M Verduijn2, Jan C Drooger4, Gerard C van Rhoon2, Dineke H P M Smedts5, Helena C van Doorn5, Joost L Boormans6, Agnes Jager7, Martine Franckena2, Roland Kanaar1. 1. a Department of Molecular Genetics , Cancer Genomics Centre Netherlands Erasmus University Medical Centre , Rotterdam , The Netherlands. 2. b Department of Radiation Oncology , Erasmus MC Cancer Institute , Rotterdam , The Netherlands. 3. c Department of Otolaryngology and Head and Neck Surgery , Erasmus University Medical Centre , Rotterdam , The Netherlands. 4. d Department of Medical Oncology , Ikazia Hospital , Rotterdam , The Netherlands. 5. e Department of Gynaecological Oncology , Erasmus University Medical Centre , Rotterdam , The Netherlands. 6. f Department of Urology , Erasmus MC Cancer Institute , Rotterdam , The Netherlands. 7. g Department of Medical Oncology , Erasmus MC Cancer Institute , Rotterdam , The Netherlands.
Abstract
PURPOSE: Hyperthermia (40-44 °C) effectively sensitises tumours to radiotherapy by locally altering tumour biology. One of the effects of heat at the cellular level is inhibition of DNA repair by homologous recombination via degradation of the BRCA2-protein. This suggests that hyperthermia can expand the group of patients that benefit from PARP-inhibitors, a drug exploiting homologous recombination deficiency. Here, we explore whether the molecular mechanisms that cause heat-mediated degradation of BRCA2 are conserved in cell lines from various origins and, most importantly, whether, BRCA2 protein levels can be attenuated by heat in freshly biopted human tumours. EXPERIMENTAL DESIGN: Cells from four established cell lines and from freshly biopsied material of cervical (15), head- and neck (9) or bladder tumours (27) were heated to 42 °C for 60 min ex vivo. In vivo hyperthermia was studied by taking two biopsies of the same breast or cervical tumour: one before and one after treatment. BRCA2 protein levels were measured by immunoblotting. RESULTS: We found decreased BRCA2-levels after hyperthermia in all established cell lines and in 91% of all tumours treated ex vivo. For tumours treated with hyperthermia in vivo, technical issues and intra-tumour heterogeneity prevented obtaining interpretable results. CONCLUSIONS: This study demonstrates that heat-mediated degradation of BRCA2 occurs in tumour material directly derived from patients. Although BRCA2-degradation may not be a practical biomarker for heat deposition in situ, it does suggest that application of hyperthermia could be an effective method to expand the patient group that could benefit from PARP-inhibitors.
PURPOSE:Hyperthermia (40-44 °C) effectively sensitises tumours to radiotherapy by locally altering tumour biology. One of the effects of heat at the cellular level is inhibition of DNA repair by homologous recombination via degradation of the BRCA2-protein. This suggests that hyperthermia can expand the group of patients that benefit from PARP-inhibitors, a drug exploiting homologous recombination deficiency. Here, we explore whether the molecular mechanisms that cause heat-mediated degradation of BRCA2 are conserved in cell lines from various origins and, most importantly, whether, BRCA2 protein levels can be attenuated by heat in freshly biopted humantumours. EXPERIMENTAL DESIGN: Cells from four established cell lines and from freshly biopsied material of cervical (15), head- and neck (9) or bladder tumours (27) were heated to 42 °C for 60 min ex vivo. In vivo hyperthermia was studied by taking two biopsies of the same breast or cervical tumour: one before and one after treatment. BRCA2 protein levels were measured by immunoblotting. RESULTS: We found decreased BRCA2-levels after hyperthermia in all established cell lines and in 91% of all tumours treated ex vivo. For tumours treated with hyperthermia in vivo, technical issues and intra-tumour heterogeneity prevented obtaining interpretable results. CONCLUSIONS: This study demonstrates that heat-mediated degradation of BRCA2 occurs in tumour material directly derived from patients. Although BRCA2-degradation may not be a practical biomarker for heat deposition in situ, it does suggest that application of hyperthermia could be an effective method to expand the patient group that could benefit from PARP-inhibitors.
Entities:
Keywords:
BRCA2; DNA repair; Hyperthermia; PARP-inhibitors; homologous recombination
Authors: Mathias S Weyland; Pauline Thumser-Henner; Katarzyna J Nytko; Carla Rohrer Bley; Simone Ulzega; Alke Petri-Fink; Marco Lattuada; Rudolf M Füchslin; Stephan Scheidegger Journal: Comput Math Methods Med Date: 2020-07-06 Impact factor: 2.238