RNA-seq profiling of a radiation resistant and radiation sensitive prostate cancer cell line highlights opposing regulation of DNA repair and targets for radiosensitization

• Published in: BMC cancer Vol. 14; no. 1; p. 808
• Main Authors: Young, Arabella, Berry, Rachael, Holloway, Adele F, Blackburn, Nicholas B, Dickinson, Joanne L, Skala, Marketa, Phillips, Jessica L, Brettingham-Moore, Kate H
• Format: Journal Article
• Language: English
• Published: England BioMed Central 04.11.2014; BioMed Central Ltd
• Subjects: Apoptosis; Biomarkers; Biomarkers, Tumor - genetics; BRCA1 Protein - genetics; BRCA1 Protein - metabolism; Cancer therapies; Cell Cycle Proteins - genetics; Cell Line, Tumor; Cell Survival - drug effects; Cell Survival - radiation effects; Colonies & territories; Councils; Deoxyribonucleic acid; DNA; DNA Repair - drug effects; DNA Repair - radiation effects; Down-Regulation - radiation effects; Enzyme Inhibitors - pharmacology; Experiments; Fanconi Anemia Complementation Group G Protein - genetics; Gene Expression Profiling; Gene Expression Regulation, Neoplastic - radiation effects; Genes; Genomes; Hospitals; Humans; Male; Minichromosome Maintenance Complex Component 7 - genetics; Niacinamide - pharmacology; Nuclear Proteins - genetics; Origin Recognition Complex - genetics; Patients; Poly(ADP-ribose) Polymerase Inhibitors; Prostate cancer; Prostatic Neoplasms - genetics; Prostatic Neoplasms - radiotherapy; Rad51 Recombinase - genetics; Rad51 Recombinase - metabolism; Radiation therapy; Radiation Tolerance - genetics; Radiation-Sensitizing Agents - therapeutic use; RNA, Messenger - analysis; Studies; Tumors; Up-Regulation - radiation effects
• ISSN: 1471-2407; 1471-2407
• DOI: 10.1186/1471-2407-14-808

Radiotherapy is a chosen treatment option for prostate cancer patients and while some tumours respond well, up to 50% of patients may experience tumour recurrence. Identification of functionally relevant predictive biomarkers for radioresponse in prostate cancer would enable radioresistant patients to be directed to more appropriate treatment options, avoiding the side-effects of radiotherapy. Using an in vitro model to screen for novel biomarkers of radioresistance, transcriptome analysis of a radioresistant (PC-3) and radiosensitive (LNCaP) prostate cancer cell line was performed. Following pathway analysis candidate genes were validated using qRT-PCR. The DNA repair pathway in radioresistant PC-3 cells was then targeted for radiation sensitization using the PARP inhibitor, niacinimide. Opposing regulation of a DNA repair and replication pathway was observed between PC-3 and LNCaP cells from RNA-seq analysis. Candidate genes BRCA1, RAD51, FANCG, MCM7, CDC6 and ORC1 were identified as being significantly differentially regulated post-irradiation. qRT-PCR validation confirmed BRCA1, RAD51 and FANCG as being significantly differentially regulated at 24 hours post radiotherapy (p-value =0.003, 0.045 and 0.003 respectively). While the radiosensitive LNCaP cells down-regulated BRCA1, FANCG and RAD51, the radioresistant PC-3 cell line up-regulated these candidates to promote cell survival post-radiotherapy and a similar trend was observed for MCM7, CDC6 and ORC1. Inhibition of DNA repair using niacinamide sensitised the radioresistant cells to irradiation, reducing cell survival at 2 Gy from 66% to 44.3% (p-value =0.02). These findings suggest that the DNA repair candidates identified via RNA-seq hold potential as both targets for radiation sensitization and predictive biomarkers in prostate cancer.