9-cis-UAB30, a novel rexinoid agonist, decreases tumorigenicity and cancer cell sternness of human neuroblastoma patient-derived xenografts

Retinoic acid (RA) therapy has been utilized as maintenance therapy for high-risk neuroblastoma, but over half of patients treated with RA relapse. Neuroblastoma stem cell-like cancer cells (SCLCCs) are a subpopulation of cells characterized by the expression of the cell surface marker CD133 and are hypothesized to contribute to drug resistance and disease relapse. A novel rexinoid compound, 9-cis-UAB30 (UAB30), was developed having the same anti-tumor effects as RA but a more favorable toxicity profile. In the current study, we investigated the efficacy of UAB30 in neuroblastoma patient-derived xenografts (PDX). Two PDXs, COA3 and COA6, were utilized and alterations in the malignant phenotype were assessed following treatment with RA or UAB30. UAB30 significantly decreased proliferation, viability, and motility of both PDXs. UAB30 induced cell-cycle arrest as demonstrated by the significant increase in percentage of cells in G1 (COA6: 33.7 +/- 0.7 vs. 43.3 +/- 0.7%, control vs. UAB30) and decrease in percentage of cells in S phase (COA6: 44.7 +/- 1.2 vs. 38.6 +/- 1%, control vs. UAB30). UAB30 led to differentiation of PDX cells, as evidenced by the increase in neurite outgrowth and mRNA abundance of differentiation markers. CD133 expression was decreased by 40% in COA6 cells after UAB30. The ability to form lumorspheres and mRNA abundance of known sternness markers were also significantly decreased following treatment with UAB30, further indicating decreased cancer cell sternness. These results provide evidence that UAB30 decreased tumorigenicity and cancer cell sternness in neuroblastoma PDXs, warranting further exploration as therapy for high-risk neuroblastoma.

Automated summary

RA therapy is commonly used for neuroblastoma but over half of patients relapse; SCLCCs are a subpopulation contributing to drug resistance and relapse; UAB30 was found to decrease tumorigenicity and cancer cell sternness in neuroblastoma PDXs.