Bis-indole derived nuclear receptor 4A1 (NR4A1) antagonists inhibit TGF?-induced invasion of embryonal rhabdomyosarcoma cells.

ABSTRACT: Transforming growth factor ? (TGF?) enhances invasion of breast and lung cancer cells through phosphorylation-dependent nuclear export of the nuclear receptor 4A1 (NR4A1, Nur77). This response is inhibited by the NR4A1 antagonist 1,1-bis(3'-indoly)-1-(p-hydroxyphenyl) methane (CDIM8) and we hypothesized that similar effects would be observed in Rhabdomyosarcoma (RMS) cells. Although some kinase inhibitors block TGF?-induced invasion of embryonal RMS (ERMS) cells, the mechanism differs from breast and lung cancer cells since NR4A1 is extranuclear in ERMS cells. However, CDIM8 blocks basal and TGF?-induced invasion of RD and SMS-CTR ERMS cell lines but not Rh30 alveolar RMS (ARMS) cells. Moreover, this response in ERMS cells was independent of SMAD7 degradation or activation of SMAD2/SMAD3. ?-Catenin silencing decreased ERMS cell invasion and CDIM8 induced proteasome-independent downregulation of ?-catenin. The novel mechanism of CDIM8-mediated inhibition of basal and TGF?-induced ERMS cell invasion was due to activation of the Bcl-2-NR4A1 complex, mitochondrial disruption, induction of the tumor suppressor-like cytokine interleukin-24 (IL-24) which in turn downregulates ?-catenin expression. Thus, the NR4A1 antagonist inhibits TGF?-induced invasion of ERMS cells through initial targeting of cytosolic NR4A1.

SUBMITTER: Shrestha R 

PROVIDER: S-EPMC7471359 | biostudies-literature | 2020

REPOSITORIES: biostudies-literature