Human NR0B2 adenoviral particles

Mammalian nuclear receptors (NRs) are transcription factors that regulate the expression of target genes and play important roles in drug metabolism, transport, and cell signaling pathways. The orphan and structurally unique receptor small heterodimer partner 1 (syn NR0B2) is not only known for its role in regulating drug responses but has also been reported to be involved in hepatocellular carcinogenesis. In fact, previous studies have shown that NR0B2 is downregulated in human hepatocellular carcinoma, suggesting that NR0B2 acts as a tumor suppressor by inhibiting cell growth and activating apoptosis in this tumor entity. Here, researchers compared NR0B2 expression in renal cell carcinoma and adjacent non-malignant transformed tissues and found significant downregulation in vivo. In addition, the effects of heterologous expression of NR0B2 on cell cycle progression and proliferation of renal-derived cells were described. Monitoring the fluorescence intensity of resazurin turnover in RCC-EW cells revealed no significant differences in metabolic activity in the presence of NR0B2. However, in cells overexpressing this NR, cell proliferation was significantly reduced and NR0B2 was more potent than currently used antiproliferative drugs. Furthermore, flow cytometric analysis showed that heterologous overexpression of NR0B2 significantly reduced the number of cells passing through the G1 phase, while on the other hand, more cells in the S/G2 phase were detected. Taken together, these data suggest that downregulation of NR0B2 may also play a role in the development and progression of renal cell carcinoma.

Previous results have shown that NR has an effect on cell proliferation. To test whether NR0B2 has a similar effect on cancer cells derived from the human kidney, the researchers tested the effect of adenoviral transfer of NR0B2 on RCC-EW cells. Heterologous transfer of NR0B2 was verified by Western blot analysis using different amounts of NR0B2 adenovirus. The adenoviral load used directly correlated with the expression level of NR0B2 protein (Figure 1A). In addition, immunofluorescence staining of NR0B2 in RCC-EW cells was significantly enhanced after infection with Ad-NR0B2, but not after exposure to the LacZ control (Ad-LacZ, Figure 1B). Importantly, H&E staining showed no significant changes in cell morphology after adenoviral infection with Ad-NR0B2 or Ad-LacZ, although some cells transduced with NR0B2 appeared larger and swollen (Figure 1C).

Figure 1. Validation of adenoviral transfer of NR0B2 (Ad-NR0B2) in RCC-EW cells. (Prestin K, et al., 2016)