Abstract P5-12-11: NSDHL knockdown decreases tightly cohesive tumorsphere formation and breast cancer stem cell population

Abstract

Abstract Background: Cholesterol biosynthesis pathway is commonly elevated or dysregulated in cancer cells and high cholesterol levels are associated with cancer progression. NAD(P)-dependent steroid dehydrogenase-like (NSDHL), an enzyme involved in cholesterol biosynthesis, has been implicated in maintaining cancer stem cell, but its role in regulating breast cancer stem cells (BCSC) remains unclear. This study aimed to uncover the molecular mechanisms by which NSDHL regulates BCSC properties.Methods: The knockdown of NSDHL was induced by an introduction of siRNA/shRNA into MCF-7 cells. A non-adherent 3D culture method based on polymer-X coating was applied for growing tumorspheres under serum-free condition. 3’ quant mRNA-sequencing, qRT-PCR, western blot, immunofluorescent staining, ELISA, flow cytometry and ALDEFLUOR assay were carried out. Immunodeficient NSG mice were used for orthotropic xenograft tumor models by injecting tumorspheres.Result: NSDHL knockdown reduced a tightly cohesive sphere formation. RNA-seq data revealed a significant upregulation of 253 DEGs and downregulation of 364 DEGs with >2-fold change in NSDHL knockdown tumorsphere. The KEGG pathway analysis showed that DEGs were mainly enriched in TGF-β signaling pathway and cell cycle. NSDHL knockdown reduced the population of BCSCs with CD44+/CD24- phenotype and high ALDH activity as well as luminal progenitors with CD49f+/EpCAM+ phenotype along with decrease in TGF-β 1 and 3 and GLI1 in tumorsphere. In orthotropic xenograft tumor models, NSDHL knockdown strongly suppressed the tumor initiation and growth.Conclusions: Our findings reveal that NSDHL has an important role in maintaining BCSC population and tumor initiating capacity, suggesting NSDHL as an attractive therapeutic target to eliminate BCSCs, and thus preventing breast cancer initiation and progression. Citation Format: So-Hyun Yoon, Hoe Suk Kim, Junhyuk Song, Sunkyu Kwon, Seungyeon Ryu, Moonjou Baek, Sangeun Lee, Han-Byoel Lee, Hyeong-Gon Moon, Dong-Young Noh, Sangyong Jon, Wonshik Han. NSDHL knockdown decreases tightly cohesive tumorsphere formation and breast cancer stem cell population [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P5-12-11.