Human NANOG lentiviral particles

The androgen receptor (AR) is a nuclear hormone receptor that functions as a key oncogene in all stages of prostate cancer progression, including progression to castration resistance following androgen deprivation therapy. Therefore, identifying and targeting key AR-regulated genes is a potential approach to prevent the proliferation of castration-resistant cancers. Transcription factors that regulate stem cell pluripotency are particularly important; many of these genes are emerging as key oncogenes in multiple tumor cell types. Among these, Nanog has previously been shown to increase self-renewal and stem-like properties in prostate cancer cells. Here, researchers show that AR signaling upregulates Nanog mRNA and protein. AR directly binds to the NANOG promoter and is not found within 75 kb of the NANOGP8 pseudogene, suggesting that the NANOG gene locus is preferentially activated. Overexpression of Nanog in LNCaP cells increases overall growth but does not confer resistance to enzalutamide or docetaxel.

Here, the researchers examined the ability of Nanog overexpression to confer resistance to antiandrogens and taxanes in vitro. Stable expression of lentiviral Nanog (LV-Nanog) or control vector (LV-GFP) was documented by Western blotting (Figure 1A). Nanog levels in LV-Nanog cells were further increased after treatment with R1881, indicating increased endogenous Nanog expression. As expected, enzalutamide treatment reduced Nanog expression to levels comparable to vehicle-treated cells (Figure 1A). Nanog expression increased in a dose-dependent manner with R1881, while enzalutamide mitigated these effects (Figure 1A). A schematic illustrates the infection, selection, pharmacologic treatment, and analysis of growth of the transduced cells (Figure 1B). To assess sensitivity to pharmacological modulators of the androgen receptor, growth analysis of Nanog-overexpressing cells was performed seven days after treatment with 1 nM R1881, 10 mM enzalutamide, or vehicle (Figure 1C). Nanog overexpression conferred an overall additive growth advantage under all conditions; however, cells were sensitive to both androgens and antiandrogens, with R1881 increasing growth and enzalutamide decreasing growth in both GFP- and Nanog-overexpressing cells (Figure 1C).

Figure 1. Nanog overexpression in LNCaP cells leads to an increase in growth, but cells remain sensitive to androgen, anti-androgen and chemotherapeutic drug treatments. (Kregel S, et al., 2014)