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Objective: To explore the effects of quercetin on autophagy and proliferation in HBV-positive liver cancer HCCLM3 cells based on STING signaling and its underlying mechanism. Methods: HCCLM3 cells were treated with quercetin (50 μmol/L or 100 μmol/L), designated as the 50 μmol/L group and 100 μmol/L group, respectively. The inhibitory effect of quercetin on HCCLM3 cells was detected using the CCK-8 method. A scratch assay was conducted to assess the impact of quercetin on the migration ability of HCCLM3 cells. A CCK8 and ROS kit was used to detect the effect of quercetin on the levels of reactive oxygen species in HCCLM3 cells. Western blotting was employed to measure the effect of quercetin on the expression of STING signaling and autophagy-related proteins in HCCLM3 cells. RNA interference technology was used to assess the effects of STING signaling inhibition on the expression of autophagy-related proteins and reactive oxygen species levels in HCCLM3 cells. The combined effects of STING activators and quercetin on HCCLM3 cell proliferation and autophagy were evaluated. The t-test was used to detect data differences between two groups, while ANOVA was employed for comparisons among multiple groups, followed by the SNK-q test for further pairwise comparisons. Results: Compared with the control group, quercetin (50 μmol/L and 100 μmol/L groups) significantly inhibited HCCLM3 cell survival activity in a dose-dependent manner (control group: 100%; 50 μmol/L group: 75.25%; 100 μmol/L group: 50.36%, P<0.01 ). Quercetin inhibited HCCLM3 cell migration in a dose-dependent manner (>2 h, control group: 187.16 μm; 50 μmol/L group: 145.22 μm; 100 μmol/L group: 88.21 μm, P<0.01), which significantly increased intracellular reactive oxygen species (ROS) levels in HCCLM3 cells (control group: 1.00; 50 μmol/L group: 1.565; 100 μmol/L group: 2.175, P<0.01). The phosphorylation level of STING was significantly increased (P<0.01), and the expression of autophagy-related protein microtubule-related protein 1A/1B light chain 3 (LC3) protein was significantly promoted (P<0.01). Compared with the quercetin group, the cell viability of the small interfering-STING+quercetin group was increased (quercetin group: 56.3%; small interfering-STING+quercetin group: 85.7%, P<0.05), while the expression of autophagy-related protein LC3 was decreased. Compared with the quercetin group, the cell viability of the quercetin+STING activator group was further decreased (quercetin group: 56.7%; quercetin+STING activator group: 35.4%, P<0.01), and the expression levels of STING and autophagy protein LC3 were significantly increased (P<0.05). Conclusions: STING signaling-regulated cell autophagy mediates the inhibitory effect of quercetin on the proliferation of HCCLM3 cells, and this effect is enhanced after administration of the STING agonist.