Destruxin B Suppresses Drug-Resistant Colon Tumorigenesis and Stemness Is Associated with the Upregulation of miR-214 and Downregulation of mTOR/?-Catenin Pathway.

ABSTRACT: BACKGROUND:Drug resistance represents a major challenge for treating patients with colon cancer. Accumulating evidence suggests that Insulin-like growth factor (IGF)-associated signaling promotes colon tumorigenesis and cancer stemness. Therefore, the identification of agents, which can disrupt cancer stemness signaling, may provide improved therapeutic efficacy. METHODS:Mimicking the tumor microenvironment, we treated colon cancer cells with exogenous IGF1. The increased stemness of IGF1-cultured cells was determined by ALDH1 activity, side-population, tumor sphere formation assays. Destruxin B (DB) was evaluated for its anti-tumorigenic and stemness properties using cellular viability, colony-formation tests. The mimic and inhibitor of miR-214 were used to treat colon cancer cells to show its functional association to DB treatment. In vivo mouse models were used to evaluate DB's ability to suppress colon tumor-initiating ability and growth inhibitory function. RESULTS:IGF1-cultured colon cancer cells showed a significant increase in 5-FU resistance and enhanced stemness properties, including an increased percentage of ALDH1+, side-population cells, tumor sphere generation in vitro, and increased tumor initiation in vivo. In support, using public databases showed that increased IGF1 expression was significantly associated with a poorer prognosis in patients with colon cancer. DB, a hexadepsipeptide mycotoxin, was able to suppress colon tumorigenic phenotypes, including colony and sphere formation. The sequential treatment of DB, followed by 5-FU, synergistically inhibited the viability of colon cancer cells. In vivo studies showed that DB suppressed the tumorigenesis by 5-FU resistant colon cells, and in a greater degree when combined with 5-FU. Mechanistically, DB treatment was associated with decreased the mammalian target of rapamycin (mTOR) and ?-catenin expression and an increased miR-214 level. CONCLUSION:We provided evidence of DB as a potential therapeutic agent for overcoming 5-FU resistance induced by IGF1, and suppressing cancer stem-like properties in association with miR-214 regulation. Further investigation is warranted for its translation to clinical application.

SUBMITTER: Wu SY 

PROVIDER: S-EPMC6209980 | biostudies-literature | 2018 Sep

REPOSITORIES: biostudies-literature