Gold nanoparticles enhance microRNA 31 detection in colon cancer cells after inhibition with chlorogenic acid

In the present study, the inhibitory effect of chlorogenic acid (CGA), a phenolic compound with potential antitumor effects, on circulating microRNA 31 (miR-31), was evaluated in RKO colon cancer cells. The capacity of gold nanoparticles (AuNPs) to enhance miR-31 quantification after treatment with CGA was assessed. RKO cells were treated with different concentrations of CGA for 24, 48 and 72 h, after which AuNPs coupled to CD81 were added to the supernatants. Total RNA was extracted, and miR-31 was quantified by reverse transcription-quantitative PCR. The results revealed an 85% decrease in miR-31 level following treatment with 1,000 µM CGA for 72 h, and the highest capacity to detect miR-31 (after treatment and isolation with AuNPs + CD81) was observed at 24 h. Furthermore, CGA decreased the expression of the miR-31 oncogene in an in vitro colon cancer model, and the use of AuNPs enhanced the levels of miRNA detection. The results suggest that miR-31 inhibition is one mechanism by which CGA decreases colon cancer cell proliferation. Moreover, AuNPs can increase the capacity of miR-31 quantification, representing a new strategy to develop non-invasive tools for the molecular diagnosis and monitoring of colon cancer.