Abstract： Objective:To investigate the effect of long non-coding RNA (lncRNA) tumor susceptibility candidate gene 9 (CASC9) on the proliferation and apoptosis of pancreatic cancer cell BxPC-3, and to identify the targeting relationship between miR-195-5p and CASC9.Methods:40 pairs of pancreatic cancer tissues and adjacent normal pancreas tissues resected by surgery and diagnosed by histopathology in Xiangyang Hospital of Integrated Traditional and Western Medicine from April 2017 to May 2018 were collected. Four pancreatic cancer cells (AsPC-1, HPAC, BxPC-3, PANC1) and normal pancreatic ductal epithelial cells HPDE6-C7 were used in experiments. The expression level of CASC9 in pancreatic cancer tissues and cell lines were detected by real-time quantitative PCR. The BxPC-3 cells were divided into si-CASC9 group (transfected with siRNA against CASC9), si-control group (transfected with siRNA that did not match CASC9), CACS9 group (transfected with CASC9 overexpressed plasmid), and CASC9/miR-195-5p group (co-transfected with CASC9 overexpressed plasmid and miR-195-5p mimics). Cell proliferation activity was detected by MTT assay. Western blot was used to detect the protein expression of Bax and Bcl-2. The targeting relationship between CASC9 and miR-195-5p was identified by bioinformatics analysis and luciferase assay.Results:The expression level of CASC9 in pancreatic cancer tissues was significantly higher than that in adjacent normal tissues (4.7±1.25 vs 2.15±0.82, P=0.04), and the expression levels of CASC9 in pancreatic cancer cell lines AsPC-1, HPAC, BxPC-3, and PANC1 cells were 1.43±0.12, 1.86±0.13, 2.03±0.14, and 1.73±0.15, respectively, which were significantly higher than that in HPDE6-C7 cells (1.00±0.10, P<0.001). The expression in BxPC-3 cells was the highest. The proliferation activity of cells in si-CASC9 group decreased significantly compared with that in si-control group (on day 3 0.57±0.05 vs 0.72±0.04, P=0.01; and on day 4 0.75±0.07 vs 0.95±0.07, P=0.02). Bax expression was up-regulated (1.39±0.13 vs 1.07±0.11, P=0.03), while Bcl-2 expression was significantly down-regulated (1.44±0.11 vs 1.71±0.12, P=0.04). The cell proliferation activity of CASC9/miR-195-5p group was significantly decreased compared with that of CASC9 group ( P<0.005). The expression level of Bax was significantly higher than that of CASC9 group (0.68±0.04 vs 0.56±0.03, P=0.01), and the expression level of Bcl-2 was significantly lower than that of CASC9 group (1.05±0.03 vs 1.47±0.04, P<0.001). Conclusions:miR-195-5p can reverse the effect of CASC9 on promoting proliferation and inhibiting apoptosis of pancreatic cancer cells by targeting lncRNA CASC9.