The plasticity of cancer stem cells (CSCs)/tumor-initiating cells (T-ICs) indicates that multiple CSC/T-IC subpopulations exist within a tumor and multiple oncogenic pathways collaborate to maintain the CSC/T-IC state. Here, we aimed to enrich for T-ICs from clinical ESCC tissues. A chemoresistant human esophageal squamous cell carcinoma (ESCC) patient-derived xenograft model was employed to identify miRNA(s) that contribute to ESCC aggressiveness. We used microarrays to demenstrate the microRNA expression underlying different pretreated conditions. NOG mice bearing subcutaneous tumor xenografts derived from clinical ESCC cells were intraperitoneally treated with CDDP or PBS twice weekly for three weeks. Tumor cells were then isolated and re-inoculated subcutaneously into NOG mice for the next round of treatment. In the 4th round of treatment, the volume of tumors in both CDDP- and PBS-treated groups were approximately the same, suggesting that the cells in CDDP-treated tumors were becoming resistant to CDDP. microRNA expression was measured by RNA extraction from cisplatin-treated tumors (EC-CR) or PBS-treated tumors(EC-UT) after 4 round of treatment,two microarrays were performed for each sample.