Inhibition Of Canonical Wnt Pathway Research Articles

Cav 1.2 regulates osteogenesis of bone marrow-derived mesenchymal stem cells via canonical Wnt pathway in age-related osteoporosis.

AimsAge‐related bone mass loss is one of the most prevalent diseases that afflict the elderly population. The decline in the osteogenic differentiation capacity of bone marrow‐derived mesenchymal stem cells (BMMSCs) is regarded as one of the central mediators. Voltage‐gated Ca2+ channels (VGCCs) play an important role in the regulation of various cell biological functions, and disruption of VGCCs is associated with several age‐related cellular characteristics and systemic symptoms. However, whether and how VGCCs cause the decreased osteogenic differentiation abilities of BMMSCs have not been fully elucidated.MethodsVoltage‐gated Ca2+ channels related genes were screened, and the candidate gene was determined in several aging models. Functional role of determined channel on osteogenic differentiation of BMMSCs was investigated through gain and loss of function experiments. Molecular mechanism was explored, and intervention experiments in vivo and in vitro were performed.ResultsWe found that Cav1.2 was downregulated in these aging models, and downregulation of Cav1.2 in Zmpste24−/− BMMSCs contributed to compromised osteogenic capacity. Mechanistically, Cav1.2 regulated the osteogenesis of BMMSCs through canonical Wnt/β‐catenin pathway. Moreover, upregulating the activity of Cav1.2 mitigated osteoporosis symptom in Zmpste24−/− mice.ConclusionImpaired osteogenic differentiation of Zmpste24−/− BMMSCs can be partly attributed to the decreased Cav1.2 expression, which leads to the inhibition of canonical Wnt pathway. Bay K8644 treatment could be an applicable approach for treating age‐related bone loss by ameliorating compromised osteogenic differentiation capacity through targeting Cav1.2 channel.

Abstract 1958: Glypican-3 (GPC3) modulates senescence, homotypic adhesion and migration of tumor mammary cells through the inhibition of the canonical Wnt pathway

Abstract The Wnt pathway is involved in regulating cell proliferation and differentiation. Alterations of this pathway have been identified as key event in neoplastic development. Previously, we have demonstrated that the restatement of Glypican-3 (GPC3), a proteoglycan downregulated in breast cancer, is able to induce an inhibition of the canonical Wnt pathway in the murine mammary adenocarcinoma LM3 cells. We also reported that GPC3 reexpression induces an inhibition of the in vivo metastatic capacity and an in vitro reversion of the epithelial to mesenchymal transition (EMT). GPC3 reexpressing clones are less viable in stress conditions, more senescent, more homotypic adherent, less migrants and their actin is mainly localized in cortical position. The aim of this study was to analyze whether the effects of GPC3 on these cellular parameters are dependent on the inhibition of canonical Wnt pathway. As a strategy, two LM3-GPC3 clones and two LM3-vector ones were treated with LiCl (activator of the Wnt pathway canonical) or NaCl as control. We determined that LiCl was able to partially reverse the LM3-GPC3 cell senescence (X-gal positive senescent cells: LM3-GPC3+NaCl=85% vs +LiCl=65%, ANOVA-Bonferroni p <0.05). In contrast, no changes were observed on the susceptibility to death by serum starving (ANOVA, ns). Although there were no effects on the actin cytoskeleton organization, we established by a wound healing assays that LM3-GPC3 cells treated with LiCl regain their ability to migrate (Wound coverage: LM3-GPC3+NaCl=15% vs +LiCl=75%, ANOVA-Bonferroni p<0.05). Interestingly, LiCl significantly reduced the homotypic adhesion of LM3-GPC3 cells, reaching control levels (ANOVA-Bonferroni p<0.05). These results suggest that inhibition of the canonical Wnt pathway induced by GPC3 mediates the effects of this glypican on senescence, migration and cell aggregation, while survival and actin cytoskeleton organization would be modulated through other pathways. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 1958. doi:10.1158/1538-7445.AM2011-1958