Pharmaceutical reversal of Dkk1-induced LRP6 endocytosis prevents cancer cachexia and prolongs survival
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ABSTRACT: Cancer cachexia with profound weight loss and frailty impairs quality of life, limits cancer therapy and decreases survival, against which no effective therapy is available. Dkk1 is a secreted antagonist of Wnt/β-catenin pathway via interacting with Wnt co-receptors LRP5 and 6 (LRP5/6) and inducing their endocytosis1-4. Although Dkk1 is critical for animal development3,5, its mRNA is undetectable in most adult organs6. Of note, elevated circulating Dkk1 leads to poor prognosis in patients with a variety of types of cancer by a completely unknown mechanism. Here, we show that administration of a recombinant Dkk1 protein accelerated cancer cachexia-related death through inducing LRP6 endocytosis but not β-catenin inhibition, whereas pharmacological blockade of Dkk1-induced membrane LRP6 downregulation completely prevented cancer cachexia and robustly prolonged survival in tumor-bearing mice. Pharmacological blockade of Dkk1-induced membrane LRP6 downregulation prevented alterations of a number of GPCR pathways and all main cancer cachexia-related pathways in skeletal muscle of mice bearing tumor as shown by a genome-wide transcriptional analysis. Furthermore, Dkk1 injection into hindlimb directly triggered activations of GPCR pathways and cachexia-related pathways. These findings establish a key role of the Dkk1-LRP6 axis in cancer cachexia development through affecting GPCR pathways and suggest a highly promising therapeutic approach for preventing cancer cachexia.
Project description:In order to characterize the differences between the co-receptors LRP5 and LRP6, we have analyzed the transcriptome of HCC38 cells - a triple negative breast cancer cell line - 24, 48 and 72 hours following the depletion of LRP5 or LRP6 using siRNAs.
Project description:Wnt signaling is a major regulator of osteoblast differentiation and function. To investigate how Wnt3a signaling regulates osteoblastic gene expression and to identify the role of Lrp5 and Lrp6 in mediating Wnt3a signaling in osteoblasts, neonatal calvarial osteoblasts isolated from C57Bl6 (WT) and osteoblasts lacking Lrp5 (Lrp5KO), Lrp6 (Lrp6KO) and, both Lrp5 and 6 (Lrp5/6KO) were treated with Wnt3a for 24 hours and gene expression changes were quantified by RNA-seq.
Project description:The canonical Wnt signaling pathway has been demonstrated as a critical role in the self-renewal, proliferation and differentiation of Hematopoietic Stem Cells (HSCs), but the functions are indeterminacy in adult HSCs since the different experimental systems using gain- or loss- functions mice models. Low-density lipoprotein receptor-related proteins 5 and 6 (LRP5 and LRP6) are important co-receptors in the canonical Wnt/β-catenin pathway. In this study, the knockout mice models were established for adult HSC investagation via conditional ablation of LRP5 and LRP6 in adult hematopoiesis by Vav-Cre Loxp system. We found the HSC numbers were diminished due to the decreased proliferation and cell cycle. To investigate the molecular mechanisms, RNA-seq was performed using HSC cells isolated from WT and dKO mice.
Project description:LRP5/6 receptor is an important receptor for the activation of β-catenin. Therefore, the downregulation of LRP5/6 can lead to the degradation of β-catenin. We sequenced mRNA from hepG2 cell after knocking down LRP5/6 or β-catenin separately by siRNA for 48hour. The different expression profile of mRNA was studied in two groups.
Project description:Using mice with targeted gene mutations, we identify (1) distinct roles for different canonical Wnt signaling components in central nervous system (CNS) vascular development and in the specification of the blood-brain and blood-retina barriers (BBB and BRB) and (2) differential sensitivities of the vasculature in various CNS regions to perturbations in canonical Wnt signaling components. We find nearly equivalent roles for Lrp5 and Lrp6 in brain vascular development and barrier maintenance but a dominant role for Lrp5 in the retinal vasculature, an especially high sensitivity of the BBB in the cerebellum and pons/interpeduncular nuclei to decrements in canonical Wnt signaling, and plasticity in the barrier properties of mature CNS vasculature. Brain and retinal vascular defects caused by loss of Norrin/Frizzled4 signaling can be fully rescued by stabilizing beta-catenin, and loss of beta-catenin’s transcriptional activation domain or expression of a dominant negative Tcf4 recapitulates the vascular development and barrier defects seen with loss of receptor, co-receptor, or ligand, indicating that Norrin/Frizzled4 signaling acts predominantly by beta-catenin-dependent transcriptional regulation. This work strongly supports a model in which identical or nearly identical canonical Wnt signaling mechanisms mediate neural tube and retinal vascularization and maintain the BBB and BRB. Total retina RNA from P10 WT, NdpKO, Ctnnb1flex3/+;Pdgfb-CreER, and NdpKO;Ctnnb1flex3/+;Pdgfb-CreER mice was subjected to RNAseq
Project description:Wnt signaling is critical for normal skeletal development as well as whole-body metabolic function. In this study, we described a previously unrecognized function for Wnt-Lrp5 signaling in the osteoblast that allows bone to acquire the resources necessary to fuel bone formation. Mice lacking the Lrp5 co-receptor specifically in osteoblasts and osteocytes exhibit the expected reductions in postnatal bone mass and also develop peripheral adiposity with corresponding reductions in energy expenditure. Conversely, mice expressing a high-bone mass mutant Lrp5 allele are leaner with reduced plasma triglyceride and free fatty acid levels. In this context, Wnt-initiated signals downstream of Lrp5, but not Lrp6, regulate the expression of key enzymes required for fatty acid β-oxidation. These results suggest that Wnt-Lrp5 signaling regulates basic cellular activities beyond those associated with fate-specification and differentiation in bone and that the skeleton influences global energy homeostasis via mechanisms independent of osteocalcin and glucose metabolism Total RNA isolated from cultures of Lrp5-deficient osteoblasts differentiated for 7 days in vitro compared to control osteoblasts
Project description:Cancer cachexia is a severe systemic wasting disease that negatively affects quality of life and survival in patients with cancer. To date, treating cancer cachexia is still a major unmet clinical need. We recently discovered the destabilization of the AMPK complex in adipose tissue as a key event in cachexia-related adipose tissue dysfunction and developed an AAV-based approach to prevent AMPK degradation and prolong cachexia-free survival. Here, we show the development and optimization of a prototypic peptide, Pen-X-ACIP, where the AMPK stabilizing peptide ACIP is fused to the cell-penetrating peptide moiety penetratin via a propargylic glycine linker to enable late-stage functionalization using click chemistry. Pen-X-ACIP was efficiently taken up by adipocytes, inhibited lipolysis and restored AMPK signaling. Tissue uptake assays showed a favorable uptake profile into adipose tissue upon intraperitoneal injection. Systemic delivery of Pen-X-ACIP into tumor-bearing animals prevented the progression of cancer cachexia without affecting tumor growth, and preserved body weight and adipose tissue mass with no discernable side effects in other peripheral organs, thereby achieving proof-of-concept. As Pen-X-ACIP also exerted its anti-lipolytic activity in human adipocytes, it now provides a promising platform for further (pre)clinical development towards a novel, first-in-class approach against cancer cachexia.
Project description:Cancer cachexia, highly prevalent in lung cancer, is a debilitating syndrome characterized by involuntary loss of skeletal muscle mass, and is associated with poor clinical outcome, decreased survival and negative impact on tumor therapy. Various lung tumor-bearing animal models have been used to explore underlying mechanisms of cancer cachexia. However, these models do not simulate anatomical and immunological features key to lung cancer and associated muscle wasting. Overcoming these shortcomings is essential to translate experimental findings into the clinic. We therefore evaluated whether a syngeneic, orthotopic lung cancer cachexia (OLCC) mouse model replicates systemic and muscle-specific alterations associated with human lung cancer cachexia. Immune competent, 11 weeks old male 129S2/Sv mice, were randomly allocated to either (1) sham control group or (2) tumor-bearing (OLCC) group. Syngeneic lung epithelium-derived adenocarcinoma cells (K-rasG12D; p53R172HΔG) were inoculated intrapulmonary into the left lung lobe of the mice. Body weight and food intake were measured daily. At baseline and weekly after surgery, grip strength was measured and tumor growth and muscle volume were assessed using micro cone beam CT imaging. After reaching predefined surrogate survival endpoint, animals were euthanized and skeletal muscles of the lower hind limbs were collected forRNA sequencing. RNA sequencing was performed on the Illumina NovasSeq 6000.