SH-imi-goldnanoparticles a possible drug target carrier: an evaluation using epigenetic histone dimethylation levels

This study refers a 2-mercapto-1-methylimidazole (SH-imi) gold nanoparticles (AuNPs )-conjugated synthesis, their interaction within different cell lines and epigenetic effect after cell internalization. We describe SH-imiAuNPs cell intake following H3K4 and H3K9 dimethylation analysis in three different cell lines: human neuroblastoma cells SH-SY5Y, androgen-responsive lymph node prostate cancer cell line LNCaP, and DU-145 cells, a non-androgen sensitive cell line. Specifically we study the level of dimethylation in H3K4 as epigenetic marker of euchromatin, and dimethylation in H3K9 as transcriptional repression marker. After an hour of treatment with SH-imiAuNPs, histones were extracted and dimethyl-H3K4 and -H3K9 evaluated. The three cell lines all show decreased levels of H3K4me2 and increased levels of H3K9me2. Additionally we observe a general chromatin closing trend within the three cell lines with minor different effect. To better understand the nanogold biological interaction we incubated SH-SY5Y for an hour using decreased concentration of SH-imiAuNPs, within the range of 100 ng/ml to1 ng/ml. We found that cell damage decrease with the concentration of gold nanoparticles. Fluorescent microscopy and binarization algorithm based on thresholding process with an RGB input image, still show the presence of SH-imiAuNPs into cells. In particular, our results underline that lower concentration of nanoparticles lead to a new characteristic nano-phenotype in which the cells reached a new steady-state healthy condition. Further, under these conditions SH-SY5Y cell lines are able to rescue cell phenotype making the system suitable for drugs nano-carrier studies.