Differential gene expression pattern of the response to neoadjuvant chemotherapy in locally advanced gastric cancer

To improve the survival of gastric cancer, neoadjuvant chemotherapy followed by surgery has been a promising treatment protocol. However, non-responders have to suffer from adverse effects and miss the opportunity of other possible treatments. To elucidate the molecular basis of the response to neoadjuvant chemotherapy, the gene expression pattern was analyzed by a microarray-based method. Based on our previous retrospective study, we examined the gene expression of twelve patients who underwent S-1 plus oxaliplatin (SOX) neoadjuvant chemotherapy before curative surgery (R0) for stage III gastric cancer. Three tumor tissues without neoadjuvant chemotherapy were collected as the control group. These three groups were compared on functional and pathway enrichment analysis. The results were mainly shown that differentially expressed genes in responders and non-responders were highly enriched for genes involved in cytokine-cytokine receptor interaction and NK cell mediated cytotoxicity. Considering the drug sensitivity of oxaliplatin and S-1, microarray analysis significantly demonstrated 3 up-regulated genes and 1 down-regulated gene in DNA damage repair pathway which may play an important role in drug resistance (responders vs. non-responders). Thus, microarray analysis can efficiently evaluate the gene expression after neoadjuvant chemotherapy for gastric cancer, which may better understand tumor chemosensitivity.