Distant metastasis is one of the most common causes for failure in treatment of advanced NSCLC, and it is a key factor to determine the patients' prognosis. This study aims to screen the microRNAs associated with non-small cell lung cancer metastasis, so as to provide theoretical basis for investigating their roles in non-small cell lung cancer metastasis. In this study, the fluorescent transfected human non-small cell lung cancer cell lines H460 developed tumors subcutaneously, which were then in situ transplanted into the left lung of nude mice to obtain the tissue specimens of primary tumor and metastatic tumor. The differentially expressed microRNAs associated with non-small cell lung cancer metastasis were identified using the microRNA microarray and real-time quantitative polymerase chain reaction (RT-PCR) analysis, and bioinformatics analysis of the microRNAs was performed. The microarray analysis results revealed that 17 microRNAs with up-regulated expression and 7 with down-regulated expression between the non-small cell lung cancer metastatic primary loci and the non-metastatic primary loci (Group A), while 20 microRNAs with up-regulated expression (ratio > 1.5 times, P < 0.05) and 16 with down-regulated expression (ratio < 0.65 times, P < 0.05) between the non-small cell lung cancer metastatic loci and the metastatic primary loci (Group B). RT-PCR validation and bioinformatics analysis of some microRNAs identified 2 microRNAs with up-regulated expression, miR-10b and miR-144, and 3 microRNAs with down-regulated expression, miR-9, miR-31 and miR-34b in Group A; and 4 microRNAs with down-regulated expression, miR-25, miR-92a, miR-202 and miR-326 in Group B, which may be mediated by transcription factors activator protein 1 (AP-1), p53, STATs and NF-κB, regulate cell development, proliferation and cycle, DNA and RNA metabolism and signal transduction pathway, and promote tumor growth and metastasis through the effects on target genes like RARβ, RASSF1 and E2F-1. In conclusion, there are differences in microRNA expression between the non-small cell lung cancer metastatic and non-metastatic tissues, which provides experimental basis for exploring the mechanism of non-small cell lung cancer metastasis and provides a potential idea for molecular diagnosis and treatment, as well as prognosis.
Keywords: Non-small cell lung cancer; metastasis; microRNA; microarray; nude mouse model; target gene.