Role of Natural Radiosensitizers and Cancer Cell Radioresistance: An Update

Abstract

Cancer originates from genetic mutations accumulation. Cancer stem cells have been depicted as tumorigenic cells that can differentiate and self-renew. Cancer stem cells are thought to be resistant to conventional therapy like chemotherapy and radiation therapy. Radiation therapy and chemotherapy damage carcinomic DNA cells. Because of the ability of cancer stem cells to self-renew and reproduce malignant tumors, they are the subject of intensive research. In this review, CSCs radioresistant mechanisms which include DNA damage response and natural radiosensitizers have been summed up. Reactive oxygen species play an important role in different physiological processes. ROS scavenging is responsible for regulation of reactive oxygen species generation. A researcher has proved that microRNAs regulate tumor radiation resistance. Ionizing radiation does not kill the cancer cells; rather, IR just slows down the signs and symptoms. Ionizing radiation damages DNA directly/indirectly. IR is given mostly in combination with other chemo/radiotherapies. We briefly described here the behavior of cancer stem cells and radioresistance therapies in cancer treatment. To overcome radioresistance in treatment of cancer, strategies like fractionation modification, treatment in combination, inflammation modification, and overcoming hypoxic tumor have been practiced. Natural radiosensitizers, for example, curcumin, genistein, and quercetin, are more beneficial than synthetic compounds.

Etoposide radiosensitizes p53-defective cholangiocarcinoma cell lines independent of their G2 checkpoint efficacies

“…Unfortunately, the efficacy of this treatment modality is low in several malignancies due to the resistance of cancer to radiation (2,3). Ionizing radiation primarily eradicates cancer cells by damaging the DNA of irradiated cells (2).…”

The role of oxidative stress in EBV lytic reactivation, radioresistance and the potential preventive and therapeutic implications

“…One reason might be due to their obvious antioxidant activities, which might contribute to decreasing the level of oxidative stress before or during treatment . Also, the potential antioxidant activities might assist them to have better biological and radioprotective effects for normal cells . Another reason might be their abilities to inhibit EBV lytic reactivation and enhance the efficiency of radiation .…”

“…[93][94][95] Also, the potential antioxidant activities might assist them to have better biological and radioprotective effects for normal cells. 45,[96][97][98][99] Another reason might be their abilities to inhibit EBV lytic reactivation 29,30,100 and enhance the efficiency of radiation. 45,[96][97][98][99] The biological activities of these antioxidant natural compounds might assume them to be effective strategies in the prevention and treatment of EBV-associated cancers.…”

“…45,[96][97][98][99] Another reason might be their abilities to inhibit EBV lytic reactivation 29,30,100 and enhance the efficiency of radiation. 45,[96][97][98][99] The biological activities of these antioxidant natural compounds might assume them to be effective strategies in the prevention and treatment of EBV-associated cancers. Specifically, one phase 2/3 trial are underway on studying the effect of EGCG on EBV reactivation in remission patients with NPC (NCT01744587, Clinical Trails.gov), 43 which demonstrated the great potential of antioxidants in NPC therapy.…”

Cerium oxide nanoparticles sensitize non-small lung cancer cell to ionizing radiation

“…There is a great interest in the use of radiosensitizers that improve the cancer treatment with radiotherapy [9,10]. Radiosensitzers are enabling to imbalance cellular oxygen and sensitize tumor cells to IR [11,12]. CeO2 cerium oxide nanoparticle (nanoceria, CNP) is developed as a therapeutic agent for oxidative stress associated diseases due to its antioxidant properties.…”