WP1 addressed cellular radiation resistance and sensitivity. WP1 successfully uncovered several means for increasing cancer cell radiosensitivity. By developing strategies that sensitize cancer cells to radiotherapy (RT) this area could have important translational implications for improving outcomes of RT.
The research topics and results by RADIATE ESRs in WP1 were:
• The mechanism of action of Dbait - the DNA repair inhibitor was studied. AsiDNA, an active form of Dbait molecule inhibited DNA repair and sensitized tumors to radiation, chemotherapy and targeted therapy, both in vitro and in vivo, while sparing normal cells and healthy tissues.
• AsiDNA was tested in model systems for its ability to radiosensitize aggressive medulloblastoma subtypes both, in vitro and in vivo, without any evidence of AsiDNA-associated toxicity, suggesting it might be a useful therapy in this disease.
• β8 integrin was found to contribute to pancreatic cancer cell radiochemoresistance. β8 integrin is overexpressed in PDAC relative to normal tissue and thus could be a target for therapy.
• The response of cancer cells to proton RT was compared to the more commonly given photon RT. The essential repair mechanisms of DNA damage after ionizing radiation by proton and photon-induced DNA damage proved to be different, suggesting radiation from these different types could have differential effects.
• Correlation between oxidative metabolism and radioresistance in human head and neck cancer cells was investigated, suggesting a link between mitochondrial metabolism and the cellular response to radiation.
WP2 asked how the tumor microenvironment affects the outcome of radiation treatment. The WP brought together projects examining how tumors change their environment to make them more resistant to therapy.
The research by RADIATE ESRs has been focused in these areas:
• Whether immunogenic cell death induced by anticancer photodynamic therapy (PDT) could enhance radiation-induced immune response. The work clearly showed that PDT led to immunogenic cell death, raising the possibility of using PDT, not only as an ablative therapy, but additionally as a stimulus to anti-tumor immunity.
• Investigations into the molecular determinants of the antineoplastic action of membrane-targeted lipid modifying drugs were completed.
• The synergistic potential of novel combinatorial treatment strategies of RT and immunotherapies against cancer in different in vivo tumor models was assessed and provided useful information for proposed and ongoing clinical trials.
• Whether NOTCH signaling regulates progenitor fate of bronchial epithelial cells after radiation. NOTCH signaling was found to have important effects in the response of undifferentiated lung epithelial progenitors to RT informing how normal lung tissues may lead to side effects after therapy.
WP3 focused on development of strategies to identify and validate potential targets for increasing tumor sensitivity to RT.
The research by RADIATE ESRs has been focused in these areas:
• Identification of TRIM37 as a novel determinant of radiosensitivity through a CRISPR screen. A study using a genome-wide CRISPR/Cas9 knockout screen, identified TRIM37 as a novel gene whose depletion causes radiation sensitivity.
• The effects of RT on the extracellular matrix (ECM) were studied. Results indicated that type V collagen, although present in the ECM of colorectal and pancreatic cancers, is downregulated following irradiation.
• The role of cancer-associated fibroblasts (CAFs) in the radiation-response of solid tumors was studied and found to be complex. The work revealed that CAFs affect tumor cell response to radiation in a context dependent fashion depending on the fibroblast and tumor cell type.
• The work on Synemin, a protein that influences the focal adhesion complex joining cells to the ECM found that Synemin promotes non-homologous end joining through the regulation of c-Abl and DNA-PKcs kinase activity. Additional results showed that Synemin plays a crucial role in regulating the DNA repair machinery, tyrosine kinase activity and radiosensitivity of HNSCC cells.
• This project sought to identify biologically active factors that were secreted after ionizing radiation. Placental growth factor proved to be such a molecule, raising the possibility that it might be involved in angiogenesis after RT.
All projects in these three work packages progressed as planned.
