Differential expression profiles of microRNAs in highly and weakly invasive/metastatic pancreatic cancer cells.

Pancreatic cancer is the eighth-leading cause of cancer-associated mortality worldwide. To date, the cellular and molecular mechanisms associated with the invasion and metastasis of pancreatic cancer remain unclear. To examine these mechanisms, a microRNA (miRNA/miR) microarray with 1,965 genes was hybridized with labeled miRNA probes from invasive PC-1.0 and non-invasive PC-1 cells for molecular profiling analysis. In addition, reverse transcription quantitative-polymerase chain reaction (RT-qPCR) was utilized to validate the microarray results. Online miRNA target prediction algorithms online were used to predict the target genes of the differentially expressed miRNAs. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) term enrichment analysis were performed for the potential targets of the differentially expressed miRNAs. The results demonstrated that 54 miRNAs were differentially expressed, of which 33 were upregulated and 21 were downregulated in the PC-1.0 cell line compared with the PC-1 cell line. A total of 6 upregulated miRNAs (miR-31, -34a, -181a, -181b, -193a-3p, and -193b) and 4 downregulated miRNAs (miR-221, -222, -484, and -502-3p) were selected from these 54 miRNAs and validated by RT-qPCR. The differentially expressed miRNAs were further validated by RT-qPCR in the human pancreatic cancer cell lines AsPC-1 (highly invasive) and CAPAN-2 (less invasive). The results revealed that 2 upregulated miRNAs (miR-34a and -193a-3p) and 4 downregulated miRNAs (miR-221, -222, -484, and -502-3p) exhibited a consistent expression pattern between the PC-1.0/PC-1 and AsPC-1/CAPAN-2 pancreatic cancer cells. The GO and KEGG enrichment analysis indicated that the mRNAs potentially targeted by miRNAs were involved in a range of biological functions. These results suggest that different miRNA expression profiles occur between highly and weakly invasive and metastatic pancreatic cancer cell lines, and may affect a variety of biological functions in pancreatic cancer.