Aptamer-based Targeted Delivery of miRNA let-7d to Gastric Cancer Cells as a Novel Anti-Tumor Therapeutic Agent

Mirnas as one of the potential therapeutic agents have been recently considered for cancer treatment. as1411 (aptncl) is a dna aptamer specifically binding to nucleolin protein on the cancer cell surface with antiproliferative effect. the aim of the study was to develop a conjugate consisting of aptncl (as targeted delivery of therapeutic agent) and mirna let-7d (as a tumor suppressor) using two different linking methods and also to evaluate the potential effect of the conjugates on the proliferation of gastric cancer (mkn-45) cell line compared to negative control cell line of human dermal fibroblast (hdf). conjugation was performed covalently by sm (peg)_2 as a bifunctional crosslinker (conjugate-1) and noncovalently,using 19bp complementary sticky end sequences (conjugate-2). nucleolin positive mkn-45and nucleolin negative hdf cells were cultured and treated with the conjugates. then, the changes in let-7d expression and cell proliferation were determined using real-time pcr and mtt methods, respectively. in mkn-45 cells, the conjugates caused significant increase in let7-d uptake compared with hdf cells (p = 0.0001). the conjugate-1, likely due to its higher stability compared with the conjugate-2, led to significantly more increase in intracellular let- 7d in mkn-45 cells (30 fold versus 15 fold, respectively, p = 0.0001). the conjugates revealed more potent antiproliferative effect against gastric cancer cells compared with aptncl alone (p = 0.0001). it was found that the aptncl-let-7d conjugate efficiently carried let-7d into the cancer cells. also, it appears that in the setting of aptncl-let-7d conjugate, let-7d and aptncl moieties could cooperate and synergistically exhibit the antiproliferative effect on cancer cells.