Panoply™ Human DRD2 Knockdown Stable Cell Line

Although long-term, persistent psychological stress in cancer patients has been shown to accelerate tumor progression, the underlying molecular mechanisms remain unclear. This study examined the effects of psychological stress on tumor progression using a stress-induced tumor-bearing mouse model (Str-tumor). Results revealed that both D2-type dopamine receptor (DRD2) and hypoxia-inducible factor-1α (HIF1α) were highly expressed in the nuclei of Str-tumors. Trifluoperazine (TFP), a DRD2 inhibitor, demonstrated superior antitumor efficacy in Str-tumors compared with the control group. These results suggest that DRD2 may mediate stress-induced malignant tumor progression. DRD2 interacts with von Hippel-Lindau protein (VHL) in the nucleus. DRD2 and HIF1α competitively bind to VHL, thereby reducing HIF1α ubiquitination-mediated degradation and enhancing epithelial-mesenchymal transition in tumor cells. TFP acts as an inhibitor of the DRD2-VHL interface, promoting HIF1α degradation. In conclusion, DRD2 may promote psychological stress-induced malignant tumor progression by activating the oxygen-independent HIF1α pathway, and TFP may be used as a therapeutic strategy for stress management in cancer patients.

Here, IF results showed that DRD2 expression (Figures 1A and B) and nuclear localization (Figure 1C) were upregulated following treatment of melanoma cells with dopamine or DRD2 overexpression. Hypoxia also induced DRD2 overexpression, but compared with dopamine, hypoxia did not effectively promote DRD2 nuclear localization. Western blot results also showed that nuclear expression of both DRD2 and HIF1α was upregulated in B16-F10 and A375 cells following treatment with dopamine and DRD2 overexpression (Figure 1D). The researchers also examined the relationship between dopamine-induced DRD2 nuclear localization and HIF1α expression under non-hypoxic conditions. Western blot results demonstrated a dose-dependent increase in DRD2 expression in B16-F10 cells treated with varying concentrations of dopamine (Figure 1E). The effect of DRD2 on HIF1α expression was also detected in DRD2-knockdown B16-F10 and A375 cells. Results showed that HIF1α expression was reduced in DRD2-knockdown B16-F10 and A375 cells (Figure 1F and G). HIF1α expression was also detected in tumor tissues exposed to stress. Results showed that HIF1α expression was higher in stressed B16F10 tumor tissues than in unstressed tumor tissues. The expression of HIF1α in the nucleus was strongly positive, and the expression ratio of nucleus to cytoplasm was upregulated in tumor tissues under stress condition (Figure 1H-J).

Figure 1. Dopamine or hypoxia stimulation promotes nuclear localization of DRD2. (Liu H, et al., 2021)