Increasing evidence has demonstrated that microRNAs (miRNAs) are key regulators of human diseases and can serve as prognostic markers for several cancers, such as pancreatic ductal adenocarcinoma (PDAC). Previous studies have revealed various functions for miR-345-5p in several cancers. However, the role and potential mechanism of miR-345-5p in PDAC have not been resolved.

Quantitative RT-PCR was performed to investigate the expression levels of miR-345-5p in pancreatic cancer tissues and cell lines, and the effect of miR-345-5p on the proliferation and invasiveness of pancreatic cancer was examined in Transwell assays with miR-345-5p overexpression. We used Western blot assay to explore the underlying mechanisms. Immunofluorescence staining was performed to examine changes in the cytoskeleton of PANC-1 cells in response to miR-345-5p. Luciferase assays were used to clarify the target and regulation mechanism of miR-345-5p.

miR-345-5p expression was downregulated in PDAC cells and tissues. Upregulated miR-345-5p expression inhibited the proliferation and metastasis of PDAC cells. We identified CCL8 as a direct target of miR-345-5p and found CCL8 expression was inversely correlated with miR-345-5p expression in PDAC samples. CCL8 could activate the NF-κB signaling pathway to promote the proliferation and invasiveness of PDAC cells. These results suggested that miR-345-5p inhibited PDAC progression by inactivating NF-κB signaling.

Here we demonstrated that miR-345-5p was a tumor-suppressive miRNA in pancreatic cancer progression by targeting CCL8. Our results suggest miR-345-5p may be a potential therapeutic biomarker for pancreatic cancer treatment.