Identification of Genes Regulating Breast Cancer Dormancy in 3D Bone Endosteal Niche Cultures

Abstract

Cancer tumor cell dormancy is a significant clinical problem in breast cancer (BrCa). We used a 3D in vitro model of the endosteal bone niche (EN), consisting of endothelial, bone marrow stromal cells and fetal osteoblasts in a 3D collagen matrix (GELFOAM™), to identify genes required for dormancy. Human triple-negative MDA-MB-231 BrCa cells, but not the bone-tropic metastatic variant, BoM1833, established dormancy in 3D-EN cultures in a p38-MAPK-dependent manner, whereas both cell types proliferated on 2D plastic or in 3D collagen alone. “Dormancy-reactivation suppressor genes” (DRSG) were identified using a genomic shRNA screen in MDA-MB-231 cells for gene knockdowns that induced proliferation in the 3D-EN. DSRG candidates enriched for genes controlling stem cell biology, neurogenesis, MYC targets, ribosomal structure and translational control. Several potential DRSG were confirmed using independent shRNAs, including BHLHE41, HBP1 and WNT3. Overexpression of the WNT3/a antagonists, secreted frizzled-related protein 2 or 4 (SFRP2/4), induced MDA-MB-231 proliferation in the EN. In contrast, overexpression of SFRP3, known not to antagonize WNT3/a, did not induce proliferation. Decreased WNT3 or BHLHE41 expression was found in clinical BrCa metastases compared to primary-site lesions, and the loss of WNT3 or BHLHE41 or gain of SFRP1, 2 and 4 in the context of TP53 loss/mutation correlated with decreased progression-free and overall survival.

Prostate cancer cell‐intrinsic interferon signaling regulates dormancy and metastatic outgrowth in bone

“…Indeed, it is known that tumor dormancy encompasses a range of stages that can rapidly evolve in response to TME dynamics and may be influenced by bone niche‐specific pressure and co‐existing tumor growth . This is supported by C1 enrichment of Bhlhe41 , previously linked to dormancy in breast and prostate cancers and more recently associated with bone‐endosteal niche dormancy in metastatic breast cancer . Unsurprisingly, metagene C3 was enriched for genes associated with cell proliferation ( Cenpe, Bub1, and Nuf2 ).…”

Breast Cancer Stem Cells as Drivers of Tumor Chemoresistance, Dormancy and Relapse: New Challenges and Therapeutic Opportunities

“…However, evaluations of TME-targeting agents should keep in mind that the mouse and the human breast microenvironments are profoundly different [151]. Therefore it is important to use suitable models, such as humanized orthotopic xenografts, patient-derived organoid cultures, or artificial niches [152,153,154], which more accurately recapitulate the human breast microenvironment.…”

The Influence of Ligand Density and Degradability on Hydrogel Induced Breast Cancer Dormancy and Reactivation

“…[46,47] This mechanism has been further supported by confirmation that overexpression of genes that suppress ERK activation occur during dormancy. [49][50][51][52] To de-termine if the parental and organotropic sublines expressed differences in the p-ERK:p-p38 ratio as a function of hydrogel formulation, cells were cultured in the hydrogels for 15 days, fixed, fluorescently labeled for phosphorylated ERK1/2 and p38 and the nucleus counterstained with Hoechst (Figure 8). Hydrogels were imaged and the mean fluorescence intensity was measured to quantify p-ERK and p-p38 expression (Figure 8, Figures S6 and S7, Supporting Information).…”