Dependence receptor UNC5A restricts luminal to basal breast cancer plasticity and metastasis

Abstract

BackgroundThe majority of estrogen receptor-positive (ERα+) breast cancers respond to endocrine therapies. However, resistance to endocrine therapies is common in 30% of cases, which may be due to altered ERα signaling and/or enhanced plasticity of cancer cells leading to breast cancer subtype conversion. The mechanisms leading to enhanced plasticity of ERα-positive cancer cells are unknown.MethodsWe used short hairpin (sh)RNA and/or the CRISPR/Cas9 system to knockdown the expression of the dependence receptor UNC5A in ERα+ MCF7 and T-47D cell lines. RNA-seq, quantitative reverse transcription polymerase chain reaction, chromatin immunoprecipitation, and Western blotting were used to measure the effect of UNC5A knockdown on basal and estradiol (E2)-regulated gene expression. Mammosphere assay, flow cytometry, and immunofluorescence were used to determine the role of UNC5A in restricting plasticity. Xenograft models were used to measure the effect of UNC5A knockdown on tumor growth and metastasis. Tissue microarray and immunohistochemistry were utilized to determine the prognostic value of UNC5A in breast cancer. Log-rank test, one-way, and two-way analysis of variance (ANOVA) were used for statistical analyses.ResultsKnockdown of the E2-inducible UNC5A resulted in altered basal gene expression affecting plasma membrane integrity and ERα signaling, as evident from ligand-independent activity of ERα, altered turnover of phosphorylated ERα, unique E2-dependent expression of genes effecting histone demethylase activity, enhanced upregulation of E2-inducible genes such as BCL2, and E2-independent tumorigenesis accompanied by multiorgan metastases. UNC5A depletion led to the appearance of a luminal/basal hybrid phenotype supported by elevated expression of basal/stem cell-enriched ∆Np63, CD44, CD49f, epidermal growth factor receptor (EGFR), and the lymphatic vessel permeability factor NTN4, but lower expression of luminal/alveolar differentiation-associated ELF5 while maintaining functional ERα. In addition, UNC5A-depleted cells acquired bipotent luminal progenitor characteristics based on KRT14+/KRT19+ and CD49f+/EpCAM+ phenotype. Consistent with in vitro results, UNC5A expression negatively correlated with EGFR expression in breast tumors, and lower expression of UNC5A, particularly in ERα+/PR+/HER2− tumors, was associated with poor outcome.ConclusionThese studies reveal an unexpected role of the axon guidance receptor UNC5A in fine-tuning ERα and EGFR signaling and the luminal progenitor status of hormone-sensitive breast cancers. Furthermore, UNC5A knockdown cells provide an ideal model system to investigate metastasis of ERα+ breast cancers.Electronic supplementary materialThe online version of this article (10.1186/s13058-018-0963-5) contains supplementary material, which is available to authorized users.

Genetic Ancestry–dependent Differences in Breast Cancer–induced Field Defects in the Tumor-adjacent Normal Breast

“…Quantitative measurements were done using the automated Aperio Imaging system and analysis was done using an FDA-approved algorithm. Positivity and H-scores were scored and statistically analyzed as described previously (14,15). With respect to PD-L1, a tumor proportion score (TPS) was conducted alongside a pathology hand score.…”

Histone demethylase KDM7A is required for stem cell maintenance and apoptosis inhibition in breast cancer

“…Possibly, KDM7A has different effects on cell proliferation between ER‐postive and ER‐negative breast cancer. In addition, the Kadua group found that estradiol (E2) can induce the expression of KDM7A and E2 target gene expression, resulting in negative regulation of cell proliferation in UNC5A‐knockdown MCF7 cells (Padua et al, ). They speculate that UNC5A may be the key factor determining whether KDM7A regulated cancer cell proliferation.…”

CRISPR/Cas9: A powerful genome editing technique for the treatment of cancer cells with present challenges and future directions

“…The breast epithelium is composed of four different subtypes based on the estrogen receptor (ER) expression, including luminal A, luminal B, Her2-enriched, and triple-negative breast cancer (TNBC) [ 40 ]. The luminal subtypes (ER-positive) are the most lethal and common forms of breast cancer of about 70% with resistance (30%) to endocrine therapies in affected patients [ 41 ]. However, a reduction of breast cancer is crucial, particularly in re-occurrence.…”