Influential Factors and Synergies for Radiation-Gene Therapy on Cancer

Radiation-gene therapy, a dual anticancer strategy of radiation therapy and gene therapy through connecting radiation-inducible regulatory sequence to therapeutic gene, leading to the gene being induced to express by radiation while radiotherapy is performed and finally resulting in a double synergistic antitumor effect of radiation and gene, has become one of hotspots in the field of cancer treatment in recent years. But under routine dose of radiation, especially in the hypoxia environment of solid tumor, it is difficult for this therapy to achieve desired effect because of low activity of radiation-inducible regulatory elements, low level and transient expression of target gene induced by radiation, inferior target specificity and poor biosecurity, and so on. Based on the problems existing in radiation-gene therapy, many efforts have been devoted to the curative effect improvement of radiation-gene therapy by various means to increase radiation sensitivity or enhance target gene expression and the expression's controllability. Among these synergistic techniques, gene circuit, hypoxic sensitization, and optimization of radiation-induced sequence exhibit a good application potential. This review provides the main influential factors to radiation-gene therapy on cancer and the synergistic techniques to improve the anticancer effect of radiation-gene therapy.