Downregulation of circular RNA circ-LDLRAD3 suppresses pancreatic cancer progression through miR-137-3p/PTN axis

Emerging evidence suggests that dysregulation of circular RNAs (circRNAs) closely associated with cancer progression. In this paper, we focus on exploring the functional role of circ-LDLRAD3 in pancreatic cancer. Gene expression was determined using quantitative reverse transcriptase polymerase chain reaction and Western blot. Cell count kit-8 and 5-ethynyl-2'-deoxyuridine assay were applied to evaluate the proliferation of PANC-1 and SW1990 cells. The migration and invasion of PANC-1 and SW1990 cells were assessed using wound healing assay and transwell invasion assay. Luciferase reporter assay was performed for target validation. The results showed that circ-LDLRAD3 was overexpressed in pancreatic cancer tissues and cell lines. Increased expression of circ-LDLRAD3 was indicative of a poor prognosis in patients with pancreatic cancer. Knockdown of circ-LDLRAD3 repressed the growth of pancreatic cancer in vitro and in vivo. miR-137-3p was identified as a direct target of circ-LDLRAD3. More importantly, upregulation of circ-LDLRAD3 could mitigate the inhibitory effect of miR-137-3p on the proliferation, migration and invasion of pancreatic cancer cells. Besides, circ-LDLRAD3 could regulate the expression of pleiotrophin (PTN) through miR-137-3p. Taken together, knockdown of circ-LDLRAD3 repressed the proliferation, migration and invasion of pancreatic cancer cells through miR-137-3p/PTN axis, providing a new mechanism for pancreatic cancer progression.