To explore the mechanism of long non-coding RNA prostate cancer-associated transcript 19 (LncRNA PCAT19) knockdown on oxaliplatin (OXA) sensitivity of human gastric cancer cells by regulating microRNA (miR)-200c-3p mediated ataxia-telangiectasia mutated proteins (ATM) and Rad3-related kinase-related kinase (ATR) / checkpoint kinase1(CHK1) signaling pathway.

Human gastric adenocarcinoma cells (AGS) were randomly divided into OXA group (8 μg·L^-1 OXA), OXA+si-NC+inh-NC group (si-NC and inh-NC co-transfected with +8 μg·L^-1 OXA), OXA+si-PCAT19+ inh-NC group (si-PCAT19 and inh-NC co-transfected +8 μg·L^-1 OXA), OXA+si-PCAT19+ miR-200c-3p inh group (si-PCAT19 and miR-200c-3p inh co-transfected +8 μg·L^-1 OXA). Cell proliferation in each group was detected by 5-acetylidene-2′-deoxyuridine assay; cell apoptosis was detected by in situ terminal transferase labeling technique; cell migration was detected by cell scratch assay; the expression levels of phosphorylated histone H2A.X (γH2A.X) and radiation-sensitive protein 51 (RAD51) were detected by immunofluorescence.

In OXA group, OXA+si-NC+inh-NC group, OXA+si-PCAT19+inh-NC group, OXA+si-PCAT19+miR-200c-3p group, the cell proliferation rates were (58.83±6.52)%, (59.42±6.86)%, (45.59±6.09)% and (55.71±7.69)%, respectively; the apoptosis rates were (20.06±2.44)%, (20.32±2.66)%, (31.74±4.43)% and (24.60±3.29)%, respectively; the migration rates were (54.50±6.14)%, (56.11±6.72)%, (31.51±4.13)% and (48.59±7.26)%, respectively; the relative fluorescence intensities of γH2A.X were 1.00±0.08, 0.97±0.12, 4.84±0.82 and 2.11±0.41, respectively; the relative fluorescence intensities of RAD51 were 1.00±0.06, 1.08±0.15, 0.22±0.04 and 0.55±0.08, respectively. There were no significant differences between OXA+si-NC+inh-NC group and OXA group (all P>0.05). The above indexes of OXA+si-PCAT19+inh-NC group were compared with those of OXA+si-NC+inh-NC group, the above indexes in OXA+si-PCAT19+miR-200c-3p inh group were compared with those of OXA+si-PCAT19+inh-NC group, the differences were statistically significant (all P<0.05).

Knockdown of LncRNA PCAT19 can affect the proliferation, migration, apoptosis and deoxyribonucleic acid repair of gastric cancer cells by targeting and negatively regulating miR-200c-3p, thereby enhancing the sensitivity of gastric cancer cells to OXA, which may be related to the ATR/CHK1 signaling pathway.