ABSTRACT

Gastric cancer is one of the most deadly cancers in the world. Early diagnosis and treatment are effective for improving the survival rate of gastric cancer, but there is a shortage of specific probes for molecular signatures. To identify the biomarkers on gastric cancer cell surface sensitively, we selected DNA aptamers against gastric cancer cell (SGC-7901) by cell systematic evolution of ligands by exponential enrichment (cell-SELEX), and validate their affinity and specificity for SGC-7901 cells. This research started with the synthesis of an 88 nucleotides (nt) single strand DNA (ssDNA) library containing a random sequence of 52 nucleotides flanked by 5' and 3' fixed regions of 18 nucleotides. SGC-7901 cells were acted as target and human gastric mucosa cells were acted as counter-target by establishing a simpler cell-SELEX technology, which we acted living cells as screen media directly, optimized PCR amplification protocols and applied biotin-streptavidin system to prepare the secondary ssDNA library. After 12 rounds of SELEX screening, the aptamers against SGC-7901 cells were enriched to a considerable degree, the binding affinity of random ssDNA pool with target cells increased to a steady state. PCR products of the last round were cloned and sequenced. There were four aptamers have the absolute identical sequence, binding assays indicated that this aptamer sequence had the highest affinity and specificity to SGC-7901 cells. The DNA aptamer as probes against SGC-7901 cells with high affinity and high specificity were obtained, it can provide an effective approach for gastric cancer diagnosis and therapy.

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(Citation: Gastric & Breast Cancer 2010; 9(3): 119-126)

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