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Abstract
Increasing evidence suggests that SET functions as an oncoprotein and promotes cancer survival and therapeutic resistance. However, whether SET affects radiation therapy (RT)-mediated anticancer effects has not yet been explored. We investigated the impact of SET on RT sensitivity in hepatocellular carcinoma (HCC). Using colony and hepatosphere formation assays, we found that RT-induced proliferative inhibition was critically associated with SET expression. We next tested a novel SET antagonist, N4-(3-ethynylphenyl)-6,7-dimethoxy-N2-(4-phenoxyphenyl) quinazoline-2,4-diamine (EMQA), in combination with RT. We showed that additive use of EMQA significantly enhanced the effects of RT against HCC in vitro and in vivo. Notably, compared with mice receiving either RT or EMQA alone, the growth of PLC5 xenografted tumor in mice receiving RT plus EMQA was significantly reduced without compromising treatment tolerability. Furthermore, we proved that antagonizing SET to restore protein phosphatase 2A-mediated phospho-Akt (p-AKT) downregulation was responsible for the synergism between EMQA and RT. Our data demonstrate a new oncogenic property of SET and provide preclinical evidence that combining a SET antagonist and RT may be effective for treatment of HCC. Further investigation is warranted to validate the clinical relevance of this approach.
Footnotes
- Received March 13, 2018.
- Accepted June 13, 2018.
This work was supported by grants from the Ministry of Science and Technology of Taiwan [MOST 105-2341-B-002-088-MY3 and 105-2314-B-075-067] and Taipei Veterans General Hospital [V105B-015 and V106B-012]; partial support was provided by Taiwan Clinical Oncology Research Foundation and Taipei Veterans General Hospital-National Yang-Ming University Excellent Physician Scientists Cultivation Program.
↵This article has supplemental material available at jpet.aspetjournals.org.
- Copyright © 2018 by The American Society for Pharmacology and Experimental Therapeutics