['To investigate the expression of let-7 and its regulation of high-mobility group A2 protein (HMGA2), and to verify the relationship between let-7, HMGA2 and the process of epithelial-mesenchymal transition (EMT), in oesophageal squamous cell carcinomas (OSCC) of Kazakh patients.', "Expression of let-7 was significantly lower in Eca109 cells than in normal oesophageal squamous epithelium (P = 2.4 × 10(-7) ). Increased accumulation of let-7 after transfection of Eca109 cells with synthetic let-7 inhibited cell proliferation. Let-7 could repress expression of HMGA2 after co-transfection with let-7 and HMGA2 (P = 0.002). Moreover, let-7 expression was observed less frequently (P = 2.0 × 10(-8) ), and HMGA2 expression more frequently (P = 1.0 × 10(-10) ), in OSCC than in normal adjacent tissues; and let-7 expression was observed less frequently in OSCC from Kazakh patients than in those from Han and Uygur patients (P = 0.041). There was a reverse correlation between expression of let-7 and HMGA2 (P = 0.018). Expression of Snail was statistically higher in Kazakhs' OSCC (P = 0.029), and was correlated with depth of invasion (P = 0.021) and HMGA2 expression (P = 0.026)."] Is hMGA2 down-regulated by microRNA let-7 and associated with epithelial-mesenchymal transition in oesophageal squamous cell carcinomas of Kazakhs?