Probes for INS

Triple-negative breast cancer (TNBC) commonly develops resistance to chemotherapy, yet markers predictive of chemoresistance in this disease are lacking. Here, we define WNT10B-dependent biomarkers for β-CATENIN/HMGA2/EZH2 signaling predictive of reduced relapse-free survival. Concordant expression of HMGA2 and EZH2 proteins is observed in MMTV-Wnt10bLacZ transgenic mice during metastasis, and Hmga2 haploinsufficiency decreased EZH2 protein expression, repressing lung metastasis. A novel autoregulatory loop interdependent on HMGA2 and EZH2 expression is essential for β-CATENIN/TCF-4/LEF-1 transcription. Mechanistically, both HMGA2 and EZH2 displaced Groucho/TLE1 from TCF-4 and served as gatekeepers for K49 acetylation on β-CATENIN, which is essential for transcription. In addition, we discovered that HMGA2-EZH2 interacts with the PRC2 complex. Absence of HMGA2 or EZH2 expression or chemical inhibition of Wnt signaling in a chemoresistant patient-derived xenograft (PDX) model of TNBC abolished visceral metastasis, repressing AXIN2, MYC, EZH2, and HMGA2 expression in vivo. Combinatorial therapy of a WNT inhibitor with doxorubicin synergistically activated apoptosis in vitro, resensitized PDX-derived cells to doxorubicin, and repressed lung metastasis in vivo. We propose that targeting the WNT10B biomarker network will provide improved outcomes for TNBC. SIGNIFICANCE: These findings reveal targeting the WNT signaling pathway as a potential therapeutic strategy in triple-negative breast cancer.

The transcription factor SOX9 is critical for prostate development, and dysregulation of SOX9 is implicated in prostate cancer (PCa). However, the SOX9-dependent genes and pathways involved in both normal and neoplastic prostate epithelium are largely unknown. Here, we performed SOX9 ChIP sequencing analysis and transcriptome profiling of PCa cells and determined that SOX9 positively regulates multiple WNT pathway genes, including those encoding WNT receptors (frizzled [FZD] and lipoprotein receptor-related protein [LRP] family members) and the downstream β-catenin effector TCF4. Analyses of PCa xenografts and clinical samples both revealed an association between the expression of SOX9 and WNT pathway components in PCa. Finally, treatment of SOX9-expressing PCa cells with a WNT synthesis inhibitor (LGK974) reduced WNT pathway signaling in vitro and tumor growth in murine xenograft models. Together, our data indicate that SOX9 expression drives PCa by reactivating the WNT/β-catenin signaling that mediates ductal morphogenesis in fetal prostate and define a subgroup of patients who would benefit from WNT-targeted therapy.

Deep penetrating nevus (DPN) is characterized by enlarged, pigmented melanocytes that extend through the dermis. DPN can be difficult to distinguish from melanoma but rarely displays aggressive biological behavior. Here, we identify a combination of mutations of the β-catenin and mitogen-activated protein kinase pathways as characteristic of DPN. Mutations of the β-catenin pathway change the phenotype of a common nevus with BRAF mutation into that of DPN, with increased pigmentation, cell volume and nuclear cyclin D1 levels. Our results suggest that constitutive β-catenin pathway activation promotes tumorigenesis by overriding dependencies on the microenvironment that constrain proliferation of common nevi. In melanoma that arose from DPN we find additional oncogenic alterations. We identify DPN as an intermediate stage in the step-wise progression from nevus to melanoma. In summary, we delineate specific genetic alterations and their sequential order, information that can assist in the diagnostic classification and grading of these distinctive neoplasms.Deep penetrating nevi (DPN) are unusual melanocytic neoplasms with unknown genetic drivers. Here the authors show that majority of DPN harbor activating mutations in the β-catenin and the MAP-kinase pathways; this characteristic can help in the classification and grading of these distinctive neoplasms.