Oncogene database

607

BCL9

B-cell CLL/lymphoma 9;BCL9;B-cell CLL/lymphoma 9

B-cell CLL/lymphoma 9 protein|B-cell lymphoma 9 protein|bcl-9|protein legless homolog

1q21

protein-coding

MicroRNAs (miRNAs) are small noncoding RNAs that function as master regulators of posttranscriptional gene expression with each miRNA negatively regulating hundreds of genes. Lysophosphatidic acid (LPA) is a mitogenic lipid present within the ovarian tumor microenvironment and induces LPA receptor activation and intracellular signaling cascades like ERK/MAPK, leading to enhanced cellular proliferation. Here, we show that in SKOV-3 and OVCAR-3 cells, LPA stimulation at concentrations ranging from 1 nmol/L to 20 mumol/L for 30 to 60 minutes increases miR-30c-2*, and this effect is mediated through a combination of receptors because knock down of multiple LPA receptors is required for inhibition. The epidermal growth factor and platelet-derived growth factor also increase miR-30c-2* transcript expression, suggesting a broader responsive role for miR-30c-2*. Thus, we investigated the functional role of miR-30c-2* through ectopic expression of synthetic miRNA precursors of mature miRNA or antagomir transfection and observed that microRNA-30c-2* reduces, and the antagomir enhances, cell proliferation and viability in OVCAR-3, cisplatin-insensitive SKOV-3 and chemoresistant HeyA8-MDR cells. Ectopic expression of miR-30c-2* reduces BCL9 mRNA transcript abundance and BCL9 protein. Consistent with this observation, miR-30c-2* ectopic expression also reduced BCL9 luciferase reporter gene expression. In comparison with IOSE cells, ALL cancer cells examined showed increased BCL9 expression, which is consistent with its role in tumor progression. Taken together, this suggest that growth factor induced proliferation mediates a neutralizing response by significantly increasing miR-30c-2* which reduces BCL9 expression and cell proliferation in SKOV-3 and OVCAR-3 cells, likely as a mechanism to regulate signal transduction downstream.

Deregulated Wnt/beta-catenin signaling underlies the pathogenesis of a broad range of human cancers, yet the development of targeted therapies to disrupt the resulting aberrant transcription has proved difficult because the pathway comprises large protein interaction surfaces and regulates many homeostatic functions. Therefore, we have directed our efforts toward blocking the interaction of beta-catenin with B cell lymphoma 9 (BCL9), a co-activator for beta-catenin-mediated transcription that is highly expressed in tumors but not in the cells of origin. BCL9 drives beta-catenin signaling through direct binding mediated by its alpha-helical homology domain 2. We developed a stabilized alpha helix of BCL9 (SAH-BCL9), which we show targets beta-catenin, dissociates native beta-catenin/BCL9 complexes, selectively suppresses Wnt transcription, and exhibits mechanism-based antitumor effects. SAH-BCL9 also suppresses tumor growth, angiogenesis, invasion, and metastasis in mouse xenograft models of Colo320 colorectal carcinoma and INA-6 multiple myeloma. By inhibiting the BCL9-beta-catenin interaction and selectively suppressing oncogenic Wnt transcription, SAH-BCL9 may serve as a prototype therapeutic agent for cancers driven by deregulated Wnt signaling.

Abnormal activation of Wnt/beta-catenin-mediated transcription is associated with a variety of human cancers. Here, we report that LATS2 inhibits oncogenic Wnt/beta-catenin-mediated transcription by disrupting the beta-catenin/BCL9 interaction. LATS2 directly interacts with beta-catenin and is present on Wnt target gene promoters. Mechanistically, LATS2 inhibits the interaction between BCL9 and beta-catenin and subsequent recruitment of BCL9, independent of LATS2 kinase activity. LATS2 is downregulated and inversely correlated with the levels of Wnt target genes in human colorectal cancers. Moreover, nocodazole, an antimicrotubule drug, potently induces LATS2 to suppress tumor growth in vivo by targeting beta-catenin/BCL9. Our results suggest that LATS2 is not only a key tumor suppressor in human cancer but may also be an important target for anticancer therapy.

Wnt/beta-catenin signaling underlies the pathogenesis of a broad range of human cancers, including the deadly plasma cell cancer multiple myeloma. In this study, we report that downregulation of the tumor suppressor microRNA miR-30-5p is a frequent pathogenetic event in multiple myeloma. Evidence was developed that miR-30-5p downregulation occurs as a result of interaction between multiple myeloma cells and bone marrow stromal cells, which in turn enhances expression of BCL9, a transcriptional coactivator of the Wnt signaling pathway known to promote multiple myeloma cell proliferation, survival, migration, drug resistance, and formation of multiple myeloma cancer stem cells. The potential for clinical translation of strategies to re-express miR-30-5p as a therapeutic approach was further encouraged by the capacity of miR-30c and miR-30 mix to reduce tumor burden and metastatic potential in vivo in three murine xenograft models of human multiple myeloma without adversely affecting associated bone disease. Together, our findings offer a preclinical rationale to explore miR-30-5p delivery as an effective therapeutic strategy to eradicate multiple myeloma cells in vivo.