Bexarotene promotes neuroblastoma SH-SY5Y cells differentiation to mature neurons with decreased proliferation

Bexarotene is an retinoid X receptor (RXR) pharmacological agonist that has been demonstrated to treat cutaneous T-cell lymphoma and promising therapeutic potential for neurological diseases. But it still remains unclear whether bexarotene participates in regulation of neuroblastoma. Human neuroblastoma SH-SY5Y cells were used as a model to investigate the neuronal differentiation impact of bexarotene. Bexarotene-cultured SH-SY5Y cells showed changes in cell morphology, adopting pyramidal shapes and extending neurites, increased expression of neuronal marker β-tubulin III and mature neurons marker Neurofilament M and upregulation of neuronal differentiation markers including growth associated protein 43 ( GAP43 ) and synaptophysin ( SYP ). SH-SY5Y cells induced by bexarotene increased the mRNA expression of glutamatergic marker glutamate-ammonia ligase ( GLUL ), GABAergic marker glutamate decarboxylase ( GAD1 ) and dopaminergic marker TH, but not cholinergic marker solute carrier family 18 member 1 ( SLC18A1 ). Functional enrichment analysis of RNAseq data revealed that the PI3K-AKT axis is the dominant signaling pathway promoting the differentiation of SH-SY5Y cells into mature and functional neurons in response to bexarotene. Additionally, we observed that SH-SY5Y cells show reduced proliferation rates accompanied by decreased expression of cyclin dependent kinase 6 ( CDK6 ) and increased expression of cyclin dependent kinase 1 ( CDK1 ) following 7-day exposure to bexarotene, suggesting bexarotene induces a quiescent state in SH-SY5Y cells. SH-SY5Y cells can be induced to mature neurons with decreased proliferation induced by bexarotene via PI3K-AKT axis. It indicates bexarotene has the potential to treat neuroblastoma.