Taken together, miRNAs have been identified as potential candidates for novel diagnostic biomarkers or therapeutic targets of cancer. MiR-10a has been reported to play important roles in the genesis and development of a variety of human cancers. For example, miR-10a is deregulated in head and neck squamous cell carcinomas and also in hepatocellular carcinoma. Furthermore, in human cervical cancer, miR-10a serves as an oncogene by regulating CHL1; down-regulation of miR-10a in chronic myeloid leukemia promotes CD34+ cells proliferation. However, the function of miR-10a and the WZ4002 structure mechanism underlying gastric carcinogenesis remain unclear. In this study, we accurately measured the expression of miR-10a in 100 patients with gastric cancer and investigated the roles of miR-10a in gastric cancer cells. We found that miR-10a was down-regulated in GC tissues and enforced expression of miR-10a repressed the proliferation, migration and invasion of GC cells. Epigenetic modifications including DNA hypermethylation, histone deacetylation and histone methylation are closely associated with gene inactivation. Promoter hypermethylation is thought to be an alternative mechanism to down-regulate tumor suppressor genes in human cancers. MiRNAs whose expression is repressed by DNA methylation have been reported in a few human cancers. To further investigate whether the downregulation of miR-10a originates from the hypermethylation of the genomic region upstream of miR-10a, we analyzed the DNA methylation of CpG island in the promoter region of miR-10a in 55 GC patients and found that down-regulation of miR-10a in GC tissues might be due to the hypermethylation of CpG sequences in its promoter. In this study, we determined that miR-10a was down-regulated in human gastric cancer partially due to its DNA promoter hypermethylation. Further studies demonstrated that overexpression of miR-10a suppressed cell proliferation, migration and invasiveness in the GC cell lines HGC-27 and MGC-803, possibly through targeting the oncogene HOXA1. MiRNAs have been reported to regulate various developmental and cellular processes, and are implicated in many human diseases, especially in cancer. MiRNAs suppress gene expression by targeting mRNAs through binding to their 39 UTRs. These miRNAs exhibit regulatory roles in the pathogenesis of cancer and are involved in cell proliferation, differentiation, apoptosis, metastasis and resistance. MiR-10a plays an important role in several cancers, including hepatocellular cancer, pancreatic cancer, acute myeloid leukemia and chronic myeloid leukemia. The abnormal expression of miR-10a is likely to play a crucial role in malignant transformation and is relative to tissue-specificity. Its deregulation may contribute to the development of stomach neoplasia. The validation of the expression of miR-10a in clinical samples demonstrated that miR-10a was down-regulated in 58 GC tissues compared with the adjacent tissues. However, Weidong Chen et al. investigated the expression of miR-10a in 33 GC cases and observed that miR-10a expression was higher in GC tissues than in the adjacent tissues.