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Pancreatic cancer is one of the most lethal digestive malignant tumors. We had previously found that microRNA-301a (miR-301a) is a oncogenic microRNA whose recognized conduce to nuclear factor-kappa B (NF-κB) activation in pancreatic cancer, yet the underlying mechanisms of miR-301a in promoting pancreatic cancer invasion and migration is obscure. In this work we found that high expression of miR-301a in human pancreatic cancer patients is related to poor survival. Overexpression of miR-301a enhances pancreatic cancer cell invasion, angiogenesis and migration, whereas inhibition of miR-301a suppresses pancreatic cancer cell invasion and reduces orthotopic pancreatic tumor growth and metastasis. Furthermore, suppressor of cytokine signaling 5 (SOCS5) is identified as a target gene of miR-301a. We found that miR-301a suppressed the expression of SOCS5 leads to janus kinase/signal transducer and activator of transcription 3 (JAK/STAT3) activation and is related to poor overall survival of pancreatic cancer patients. Taken together, our data show for the first time that the feedback loop between miR-301a and JAK/STAT3 pathway may play a significant role in pancreatic cancer invasion and metastasis. Targeting the loop may prove beneficial to prevent metastasis and provide a more effective therapeutic strategy for pancreatic cancer.

To determine the role of miR-25 in non-small cell lung cancer (NSCLC), we first detected miR-25 expression in clinical specimens and lung cancer cell lines by quantitative real-time polymerase chain reaction. The levels of miR-25 were elevated in the plasma of NSCLC patients and NSCLC cell lines. Transfection of A549 and 95-D cells with a miR-25 inhibitor resulted in reduced cell proliferation and enhanced apoptosis. Moreover, the modulator of apoptosis 1 (MOAP1) gene was identified as a novel target of miR-25. The ability of miR-25 to promote cell proliferation and block apoptosis is attributable to its effect on MOAP1 suppression. In addition, miR-25 antagomir significantly inhibited lung cancer growth via upregulation of MOAP1 in a mouse xenograft model. Collectively, these data demonstrate that miR-25 is an important biomarker for lung cancer, and miR-25 promotes cell proliferation and inhibits apoptosis in NSCLC cells by negatively regulating MOAP1 expression.

Pancreatic cancer (PC) is a highly invasive tumor with early metastasis and poor prognosis, yet the mechanisms for tumor progression have not been fully elucidated. Emerging evidence indicates that microRNA-331-3p (miR-331-3p) plays an important role in the progression of diverse human cancers. Here, we found that miR-331-3p was significantly upregulated in tumor specimens of PC patients and PC cell lines. Functional studies showed that downregulation of miR-331-3p inhibited PC cell proliferation and epithelial-mesenchymal transition (EMT)-mediated metastasis in vitro. Furthermore, suppression of tumorigenicity 7 like (ST7L) was identified as a novel target gene of miR-331-3p. Tumor promotion effects of miR-331-3p were partially reversed by ST7L re-expression. In addition, miR-331-3p antagomir suppressed PC tumor growth and metastasis via upregulation of ST7L in xenograft mice. In summary, these results demonstrate that miR-331-3p is a tumor-promoting microRNA (miRNA) in PC cells and a promising biomarker for PC.