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Allosteric p97 inhibitors to overcome ATP‐competitive inhibitors resistance in anticancer therapy
Author(s) -
WANG FENG,
Gan Taiping,
Chou TsuiFen
Publication year - 2018
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.2018.32.1_supplement.807.6
Subject(s) - allosteric regulation , mutant , enzyme , atpase , mechanism of action , biology , mutation , drug resistance , cancer cell , biochemistry , pharmacology , cancer , in vitro , genetics , gene
Resistance mutations occurring on desired targets inside cancer cells, leading to loss of treatment effectiveness is a major challenge of targeted therapy; therefore, developing related small molecules with different mechanisms of action at different binding sites could be an effective strategy to overcome the resistant mutations. The ATPase enzyme, p97, is a promising target for cancer therapy because it is vital to cancer cell growth and survival. Development of resistance to existing ATP‐competitive p97 inhibitors such as CB‐5083 inspired identification of p97 inhibitors with different mechanisms of action. One approach to overcome CB‐5083 resistance is to use different classes of p97 inhibitors and therefore, we determined the potency of four ATP competitive p97 inhibitors (DBeQ, ML240, ML241, and CB‐5083) and two allosteric p97 inhibitors (NMS‐873 and UPCDC‐30245) using recombinantly purified CB‐5083 resistant p97 mutants and CB‐5083 resistant HCT116 colon cancer cells. Our results demonstrated that two known CB‐5083 resistant mutants (N660K and T688A p97) were consistently resistant to ATP‐competitive p97 inhibitors whereas allosteric p97 inhibitors NMS‐873 and UPCDC‐30245 were still active toward these mutants. The binding affinity of CB‐5083 to p97 mutants N660K and T688A is lower than to WT p97, which may be the mechanism of CB‐5083 drug resistance. To evaluate the effect of a single site mutation at N660 or T688 on p97 itself, we conducted steady state kinetic analysis. The results suggested that these mutations change the conformation of the p97 ATPase. N660K mutation decreased the K m of ATP to p97 whereas T688A decreased k cat of ATP hydrolysis. While CB‐5083, NMS‐873 and UPCDC‐30245 all effectively inhibited parent HCT116 cancer cell proliferation, allosteric p97 inhibitors (NMS‐873 and UPCDC‐30245) exhibited similar potency in inhibiting CB‐5083 resistant HCT116 cancer cell proliferation, which was more than 50‐fold resistance to CB‐5083. This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .