Date of Award

Fall 12-19-2019

Document Type


Degree Name

Master of Science (MS)


Pharmaceutical Sciences

First Advisor

Sun Yang

Second Advisor

Miao Zhang

Third Advisor

Keykavous Parang

Fourth Advisor

Kamaljit Kaur


Apurinic/apyrimidinic DNA repair endonuclease-1 (APE1), first recognized as an important DNA excision repair enzyme, is also known as Redox Factor-1 (Ref-1) involved in the activation of many nuclear transcription factors in both redox-dependent and independent manner. It has been well-documented that the overexpression of APE/Ref-1 contributes to the development of chemo-resistance and is associated with tumor progression in many human malignancies [1].

Our previous study in melanoma demonstrated that the development of novel inhibitors targeting the redox regulation domain of APE/Ref-1 is a promising strategy for melanoma treatment. To date, limited successes have been reported in developing novel APE/Ref-1 inhibitors for cancer treatment. Utilizing a structure-based approach, our study identified and characterized small molecular inhibitors of APE/Ref-1. First, N-terminally truncated APE/Ref-1 protein lacking the first 40 amino acid residues (∆40APE-1wt) was cloned into the pGEX-6P1 vector to express the GST-∆40APE-1wtprotein. After cleavage of GST-tag, the concentrated ∆40APE-1wt protein was subjected to protein crystallization study. We have successfully diffracted ∆40APE-1wt crystals and collected data with a resolution of 1.57Å. The crystal structure was further determined by molecular replacement in Molrep using the already available human APE-1 structure (PDB: 5CFG). For the first time, we observed the dimerization of APE/Ref-1 protein formed under oxidative conditions, which may contribute to the redox regulation of APE/Ref-1. Such structural transformation of APE/Ref-1 protein under distinct redox conditions may pave the way for future drug development and optimization. The binding affinity of the candidate compounds with ∆40APE-1wt protein was also determined using Surface Plasmon Resonance (SPR), and the Ki values were analyzed. One of the potent inhibitors developed by our group by structure-based approach, exhibited promising anti-melanoma activities both in vitro and in vivo. Future studies on the structure-activity association are warranted.

Creative Commons License

Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.



To view the content in your browser, please download Adobe Reader or, alternately,
you may Download the file to your hard drive.

NOTE: The latest versions of Adobe Reader do not support viewing PDF files within Firefox on Mac OS and if you are using a modern (Intel) Mac, there is no official plugin for viewing PDF files within the browser window.