miR-32-5p suppresses the proliferation and migration of pancreatic adenocarcinoma cells by targeting TLDC1

Pancreatic adenocarcinoma (PAAD) is one of the most fatal types of cancer in humans. However, the molecular mechanisms underlying the migration and invasion abilities of PAAD cells remain unclear. The aim of the present study was to explore the regulatory roles of microRNA (miR)-32-5p in PAAD cells. miR-32-5p mimic and inhibitor were used to transfect the human PAAD AsPC-1 cell line to determine the role of miR-32-5p in cell proliferation and metastasis. The starBase database predicted the binding of miR-32-5p to the target gene TBC/LysM-associated domain containing 1 (TLDC1). Further analyses were performed to assess miR-32-5p and TLDC1 expression levels in healthy and PAAD tissues, as well as the association between miR-32-5p or TLDC1 expression and the prognosis of patients with PAAD. The interaction between miR-32-5p and TLDC1 was verified using the dual-luciferase reporter assay. miR-32-5p and TLDC1 expression levels were detected by reverse transcription-quantitative PCR and western blotting, respectively. The Cell Counting Kit-8 assay was utilised to assess cell proliferation, whereas the wound-healing and Transwell assays were conducted to assess cell migration and invasion, respectively. miR-32-5p expression levels were markedly lower in PAAD tissue compared with those in healthy tissue, and were significantly lower in PAAD cell lines compared with those in the human pancreatic duct cell line HPDE6, which corresponded with poor prognosis. miR-32-5p significantly inhibited the proliferation of PAAD cells and markedly reduced migration and invasion compared with the negative controls. miR-32-5p was shown to target TLDC1, with miR-32-5p expression in PAAD being negatively correlated with TLDC1 expression. High TLDC1 expression levels were associated with a poorer prognosis compared with low TLDC1 expression levels. Co-transfection of miR-32-5p mimic and pcDNA/TLDC1 demonstrated that TLDC1 significantly reversed miR-32-5p-mediated inhibition of the proliferation, migration and invasion of PAAD cells. Overall, the present study demonstrated that miR-32-5p may serve as a tumor-suppressor gene by inhibiting the proliferation and migration and invasion of PAAD cells via the downregulation of TLDC1. Therefore, miR-32-5p may serve as a potential diagnostic or prognostic marker for PAAD.