Inhibition of NR4A1 Promotes ROS Accumulation and IL24-Dependent Growth Arrest in Rhabdomyosarcoma

Abstract

Nuclear receptor 4A1 (NR4A1, Nur77) is overexpressed in rhabdomyosarcoma (RMS), and inactivation of NR4A1 (siNR4A1) or treatment with the NR4A1 antagonist 1,1-bis (3 0 -indoly)-1-(p-hydroxy-phenyl)methane (DIM-C-pPhOH) has antiproliferative and proapoptotic effects on RMS cells. However, the mechanism by which NR4A1 inhibition exerts these effects is poorly defined. Here, we report that NR4A1 silencing or inhibition resulted in accumulation of reactive oxygen species (ROS) and ROS-dependent induction of the tumor suppressor-like cytokine IL24 in RMS cells. Mechanistically, NR4A1 was found to regulate the expression of the proreductant genes thioredoxin domain-containing 5 (TXNDC5) and isocitrate dehydrogenase 1 (IDH1), which are downregulated in RMS cells following NR4A1 knockdown or inhibition. Silencing TXNDC5 and IDH1 also induced ROS accumulation and IL24 expression in RMS cells, suggesting that NR4A1 antagonists mediate their antiproliferative and apoptotic effects through modulation of proreductant gene expression. Finally, cotreatment with the antioxidant glutathione or IL24-blocking antibody reversed the effects of NR4A1 inhibition, demonstrating the importance of both ROS and IL24 in mediating the cellular responses.Implications: Overall, these data elucidate the mechanism by which NR4A1 inhibition functions to inhibit the proliferation, survival, and migration of RMS cells.

Flavonoids Kaempferol and Quercetin are Nuclear Receptor 4A1 (NR4A1, Nur77) Ligands and inhibit Rhabdomyosarcoma Cell and Tumor Growth

“…A recent study reported that the avonoid kaempferol decreased G9a expression in gastric cancer cells (30) and this was accompanied by growth inhibition, induction of markers of apoptosis and inhibition of mTOR signaling by induced phosphorylation of AMPK. This pattern of responses observed for kaempferol in gastric cancer cells has previously been observed for CDIM/NR4A1 antagonists or NR4A1 silencing in RMS and other cancer cell lines (21)(22)(23)(24)(25)(26)(27). Therefore, we hypothesized that kaempferol is an NR4A1 ligand and this study shows for the rst time that both kaempferol and quercetin bind NR4A1 and act as NR4A1 antagonists in RMS cells.…”

“…and other cancer cell lines and the anticancer activities of bis-indole derived (CDIMs) which are NR4A1 ligands that act as receptor antagonists (21)(22)(23)(24)(25)(26)(27). The fusion oncogene PAX3-FOX01 and G9a have been characterized as highly pro-oncogenic factors in RMS (28, 29) and NR4A1 regulated expression of both genes and also β1-integrin and treatment of RMS cells with CDIM/NR4A1 antagonists decreased expression of these genes (21,25).…”

The NRF2, Thioredoxin, and Glutathione System in Tumorigenesis and Anticancer Therapies

“…This in turn inhibits the growth and induces apoptosis of rhabdomyosarcoma. [214] TXNDC5 expression might be induced under hypoxic conditions by upregulating HIF1α and thus supporting the tumorigenesis of colorectal cancer cells. [166] Inhibition of TXNDC5 promotes the expression of serpin peptidase inhibitor, clade F, and TNF receptor-associated factor 1, inducing apoptosis and inhibiting angiogenesis in cervical cancer.…”

“…Among the TXNDCs, TXNDC5 can have a role in both tumor progression and tumor suppression. The inactivation or downregulation of nuclear receptor 4A1 (NR4A1) downregulates TXNDC5, isocitrate dehydrogenase 1, and the mTOR (mammalian target of rapamycin) pathway, further promoting ROS generation, inducing apoptosis, and inhibiting tumor growth [ 214 , 215 , 216 ]. The downregulation of TXNDC5 was also reported to inhibit angiogenesis [ 217 ].…”

Clinical Significance of the Interleukin 24 mRNA Level in Head and Neck Squamous Cell Carcinoma and Its Subgroups: An In Silico Investigation

“…IL24 can protect the body via the induction of tumor cell apoptosis and inhibition of angiogenesis [ 10 , 11 ] in cancers such as colorectal adenocarcinoma and hepatic carcinoma [ 34 , 35 ]. IL24 has also been found in many diseases involving inflammation, such as cardiovascular disease, rheumatoid arthritis, tuberculosis , and viral infections, and may play a role in psoriasis [ 15 , 36 ]. In addition, many studies have shown that IL24 mRNA can be used as a potential tumor treatment [ 37 , 38 ].…”