Mitochondrial targeting of TR3 is involved in TPA induced apoptosis in breast cancer cells

Blocking PPARγ interaction facilitates Nur77 interdiction of fatty acid uptake and suppresses breast cancer progression

Nuclear receptor Nur77 participates in multiple metabolic regulations and plays paradoxical roles in tumorigeneses. Herein, we demonstrated that the knockout of Nur77 stimulated mammary tumor development in two mouse models, which would be reversed by a specific reexpression of Nur77 in mammary tissues. Mechanistically, Nur77 interacted and recruited corepressors, the SWI/SNF complex, to the promoters of CD36 and FABP4 to suppress their transcriptions, which hampered the fatty acid uptake, leading to the inhibition of cell proliferation. Peroxisome proliferator-activated receptor-γ (PPARγ) played an antagonistic role in this process through binding to Nur77 to facilitate ubiquitin ligase Trim13-mediated ubiquitination and degradation of Nur77. Cocrystallographic and functional analysis revealed that Csn-B, a Nur77-targeting compound, promoted the formation of Nur77 homodimer to prevent PPARγ binding by steric hindrance, thereby strengthening the Nur77's inhibitory role in breast cancer. Therefore, our study reveals a regulatory function of Nur77 in breast cancer via impeding fatty acid uptake.

Meriolin1 induces cell cycle arrest, apoptosis, autophagy and targeting the Akt/MAPKs pathways in human neuroblastoma SH-SY5Y cells

OBJECTIVES

Meriolins, a kind of chemical hybrid between meridianins and variolins, have lately been determined as kinase inhibitors and reportedly have antitumour activity. However, there is currently no in-depth study for the action mechanism. This study aimed to elucidate the potentially antitumour action mechanism of Meriolin1 on human neuroblastoma (SH-SY5Y) cells.

METHODS

Firstly, cell viability was detected by MTT assay. Secondly, cell cycle, cell apoptosis, cell autophagy, reactive oxygen species and mitochondrial membrane potential (ΔΨm) were measured by flow cytometry. Then, cell cycle-associated proteins, Bcl-2 family proteins, Akt/MAPK proteins and autophagy-associated proteins expressions were evaluated by Western blot. Bcl-2 and Bax mRNA expressions were also evaluated by qRT-PCR. Furthermore, cell adhesion assay and Hoechst 33258 fluorescent staining were carried out to detect the effect of Meriolin1 on cell adhesion and morphology. Finally, to gain further insight into mechanism of action of Meriolin1 to CDK protein, the molecular docking study was performed by using the CDOCKER module of DS software.

KEY FINDINGS

Meriolin1 could exert the antitumour activity on SH-SY5Y cells by inducing cell cycle arrest, cell autophagy, the mitochondrion-dependent cell apoptosis and targeting the Akt/MAPKs signalling pathway.

CONCLUSIONS

Meriolin1 might be a promising therapeutic candidate for neuroblastoma.