β-Catenin-regulated ALDH1A1 is a target in ovarian cancer spheroids

Abstract

Cancer cells form three dimensional (3D) multicellular aggregates (or spheroids) under non-adherent culture conditions. In ovarian cancer (OC), spheroids serve as a vehicle for cancer cell dissemination in the peritoneal cavity, protecting cells from environmental stress-induced anoikis. To identify new targetable molecules in OC spheroids, we investigated gene expression profiles and networks upregulated in three dimensional (3D) versus traditional monolayer culture conditions. We identified ALDH1A1, a cancer stem cell marker as being overexpressed in OC spheroids and directly connected to key elements of the β-catenin pathway. B-catenin function and ALDH1A1 expression were increased in OC spheroids vs. monolayers and in successive spheroid generations, suggesting that 3D aggregates are enriched in cells with stem cell characteristics. B-catenin knockdown decreased ALDH1A1 expression levels and β-catenin coimmunoprecipitated with the ALDH1A1 promoter, suggesting that ALDH1A1 is a direct β-catenin target. Both siRNA mediated β-catenin knockdown and A37, a novel ALDH1A1 small molecule enzymatic inhibitor described here for the first time, disrupted OC spheroid formation and cell viability (p<0.001). B-catenin knockdown blocked tumor growth and peritoneal metastasis in an OC xenograft model. These data strongly support the role of β-catenin regulated ALDH1A1 in the maintenance of OC spheroids and propose new ALDH1A1 inhibitors targeting this cell population.

Inactivation of AKT, ERK and NF-κB by genistein derivative, 7-difluoromethoxyl-5,4′-di-n-octylygenistein, reduces ovarian carcinoma oncogenicity

“…These subpopulations of cancer cells are believed to have CSC characteristics such as self-renewal ability and unlimited differentiation. Our group and other investigators have demonstrated that the spheroids of established ovarian cancer cell lines and transplanted human ovarian cancer possess the characteristics of OVCSLCs (3,4,(11)(12)(13)(14). In the present study, we also identified the characteristics of OVCSLCs in spheroids obtained from SKOV3 cells.…”

Comparative Proteomics of Ovarian Cancer Aggregate Formation Reveals an Increased Expression of Calcium-activated Chloride Channel Regulator 1 (CLCA1)

“…Recent studies have highlighted that cell behavior and gene expression profiles vary between cells grown in monolayers versus those that are grown as MCAs (11,23). Given that these differences result in an increased invasiveness and chemoresistance, a better understanding of how these spheroids form could lead to more effective approaches to treat the disease.…”

“…Thus far, it is believed that interactions between various cell adhesion molecules and extracellular matrix components contribute to the formation of MCAs, including integrins, fibronectin, and cadherins (5,7,8,12). Interestingly, studies have also shown that gene and protein expression can differ between cancer cells grown in monolayers versus those within multicellular aggregates (11,13). Thus, a global comprehensive proteomics analysis that compares the proteome of the two cell populations may add to our current understanding about OvCa progression, as well as aid in the identification of novel therapeutic targets.…”

“…□ S This article contains supplemental dissemination (7)(8)(9)(10). Numerous studies have highlighted the ability of spheroids to acquire chemoresistant, and stem-like properties, both of which have major implications for disease outcome (6,11). Thus far, it is believed that interactions between various cell adhesion molecules and extracellular matrix components contribute to the formation of MCAs, including integrins, fibronectin, and cadherins (5,7,8,12).…”

Ascites in Ovarian Cancer Progression: Opportunities for Biomarker Discovery and New Avenues for Targeted Therapies

“…In addition, β-catenin-regulated ALDH1A1, a known cancer stem cell marker, has also been implicated in the formation of multicellular spheroids [48]. Recent studies suggest that tumor cells possess varying capacity for spheroid formation [45, 47,49].…”