MicroRNA Profile of Tumorigenic Cells During Carcinogenesis of Lung Adenocarcinoma

To obtain microRNA (miRNA) profile and clarify their biological function in tumorigenic Sca‐1⁺CD34⁺ cells during carcinogenesis of lung adenocarcinoma. After intranasal infection with recombinant Adeno‐Cre viruses (AdV‐Cre), lung adenocarcinoma was identified pathologically in Lox‐stop‐lox Kras (LSL‐Kras) G12D mice. Sca‐1⁺CD34⁺ cells were sorted by flow cytometry and tested for tumor‐initiating ability, self‐renewal and tumorigenicity. MiRNA profiles were obtained using microarray and further confirmed by real‐time RT‐PCR (qRT‐PCR). MiRNA functions were predicted bioinformatically, and miR‐294 function was verified to explore its role in tumor migration and invasion. Lung adenocarcinoma was induced in LSL‐Kras G12D mice within 30 days. In vivo, the tumorigenicity of Sca‐1⁺CD34⁺ cells was 25 times stronger than Sca‐1^?CD34^? cells. During tumorigenesis of lung adenocarcinoma, the expression of 145 miRNAs in Sca‐1⁺CD34⁺ cells increased and 72 miRNAs decreased (P < 0.01). Four successively up‐regulated miRNAs (miR‐15a*, miR‐203, miR‐294 and miR‐295*) and three successively down‐regulated ones (miR‐19b, miR‐483 and miR‐615–5p) were identified. Among them, miR‐294 could constitutively bind to 3'‐UTR of matrix metalloproteinase 3 (MMP3), and down‐regulate MMP3 protein expression. MiR‐294 also significantly inhibited migration and invasion of Lewis lung cancer cells. MiRNAs are characteristically expressed in tumor‐initiating Sca‐1⁺CD34⁺ cells of lung adenocarcinoma, and may play important roles during the carcinogenesis of lung adenocarcinoma. J. Cell. Biochem. 116: 458–466, 2015. © 2014 The Authors. Journal of Cellular Biochemistry published by Wiley Periodicals, Inc.