Gene expression profiling induced by electron and proton irradiation in breast cancer cells

Radiation therapy (RT) remains a vital component of the curative multimodality therapy for many types of cancer including breast cancer (BC) disease. Thus, many efforts from research teams are needed to help clinicians in understanding the molecular portrait of a specific cancer type. Moreover, technological advances in RT are evolving with the use of hadrons, such as protons. However, cell and molecular changes induced by proton exposure are poorly characterized as well as molecular differences induced by high and low Linear Energy Transfer (LET) irradiation modalities, representing a topic of radiobiological interest. We analyze and compare molecular responses, in term of gene expression profile (GEP) changes, induced by conventional and non conventional radiation treatment modalities characterized by different LET values (using electron and proton beams respectively), delivering the same dose of IR, in tumorigenic and non-tumorigenic breast cell lines. We trust that this study could have a role in driving RT towards personalised treatments, evaluating possible combined treatments, based also on the molecular characterization in BC. Changes in gene expression in non- tumorigenic MCF10A breast epithelial cell line and in tumorigenic MCF7 and MDA-MB-231 breast cancer cell lines, exposed to 9Gy of electron or proton irradiation, were analyzed as two-color hybridizations using Agilent Technologies whole human genome 4x44K microarrays. Samples were named as follow: MCF10A_9Gy_electron; MCF7_9Gy_electron; MDA-MB-231_9Gy_electron; MCF10A_9Gy_proton; MCF7_9Gy_proton; MDA-MB-231_9Gy_proton.