FZD8

FZD8 is a seven-transmembrane Frizzled-family receptor that transduces canonical Wnt/β-catenin signaling and, through this pathway, governs both neural progenitor proliferation during corticogenesis and pro-malignant cell behavior across multiple cancers (PMID:25702574, PMID:28602974). In neural development, FZD8 expression is set by the human-accelerated enhancer HARE5, which physically contacts the Fzd8 promoter; elevated FZD8 accelerates the neural progenitor cell cycle and increases neocortical size (PMID:25702574). In cancer, FZD8 acts upstream of β-catenin to drive stem-like phenotypes, migration, invasion, and chemoresistance: it is required for cross-talk between c-Met and Wnt signaling in head and neck squamous carcinoma stem-like cells (PMID:25320014), promotes prostate cancer migration, invasion, and bone metastasis (PMID:28602974), and sustains β-catenin and survivin to confer chemoresistance in triple-negative breast cancer (PMID:23445611). FZD8 abundance is controlled at several layers: it is transcriptionally repressed by wild-type p53 binding its promoter (PMID:28602974) and by miR-375 targeting its transcript (PMID:25619565), its mRNA is regulated by ALKBH1-mediated m7G methylation that suppresses the FZD8/β-catenin axis (PMID:41274478), and its protein is stabilized by the deubiquitinase USP14 (PMID:40318610). FZD8 also contributes to bone homeostasis, with knockout shifting the balance toward osteoclasts over osteoblasts [PMID:bio_10.1101_2025.01.19.633799].

1. 2005 Low

   Defined the predicted architecture of FZD8 as a Wnt-receptor-type protein, establishing the structural framework for its receptor function.

   Evidence Comparative genomics sequence analysis across vertebrate orthologs identifying an N-terminal Fz domain, leucine zipper, Dvl-binding motif, and glycosylation sites

   PMID:15809770

   Open questions at the time

   • Computational prediction only, no biochemical validation of domain functions
   • Does not demonstrate ligand binding or signaling
2. 2013 Medium

   Linked FZD8 to therapy resistance, showing FZD8-driven Wnt signaling protects tumor cells from chemotherapy.

   Evidence siRNA knockdown of FZD8 with β-catenin/survivin readouts and NOD/SCID xenograft in triple-negative breast cancer

   PMID:23445611

   Open questions at the time

   • Ligand and receptor activation mechanism not addressed
   • Single lab, no direct structural binding data
3. 2014 Medium

   Positioned FZD8 as a node connecting c-Met to Wnt/β-catenin signaling required for cancer stem-like phenotypes.

   Evidence siRNA silencing, ectopic FZD8 rescue of c-Met-inhibited phenotype, pharmacologic c-Met inhibition, and xenografts in head and neck carcinoma stem-like cells

   PMID:25320014

   Open questions at the time

   • ERK/c-Fos to FZD8 transcriptional link inferred, not directly mapped at the promoter
   • Single lab
4. 2015 High

   Demonstrated that the level of FZD8 expression directly tunes neural progenitor cell-cycle pace and brain size, revealing a developmental role beyond cancer.

   Evidence Chromosome conformation capture plus humanized HARE5::Fzd8 transgenic mice with cell-cycle and brain-size quantification

   PMID:25702574

   Open questions at the time

   • Downstream Wnt effectors mediating cell-cycle change in progenitors not dissected
   • Receptor signaling mechanism inferred from expression dosage
5. 2015 Medium

   Identified miR-375 as a post-transcriptional repressor placing FZD8 upstream of β-catenin in synoviocytes.

   Evidence Luciferase reporter validation of miR-375 targeting plus β-catenin epistasis rescue in fibroblast-like synoviocytes

   PMID:25619565

   Open questions at the time

   • Effect generality across cell types unknown
   • Single lab
6. 2017 Medium

   Established direct transcriptional repression of FZD8 by wild-type p53 and tied FZD8 to prostate cancer bone metastasis.

   Evidence ChIP of p53 at the FZD8 promoter with gain/loss-of-function and an in vivo bone metastasis model

   PMID:28602974

   Open questions at the time

   • Mechanism linking FZD8/Wnt to the metastatic bone niche not resolved
   • Single lab
7. 2023 Medium

   Provided structure-guided antibodies that selectively block FZD8-mediated Wnt activation, confirming FZD8 as a tractable signaling receptor.

   Evidence Synthetic antibody library selection, structure of the pF8_AC3–FZD8 complex, and cell-based Wnt reporter assays

   PMID:37926311

   Open questions at the time

   • Functional antibody activity shown only in cell-based reporters, not in vivo
   • Single study
8. 2025 Medium

   Defined two additional regulatory layers controlling FZD8 abundance: USP14-mediated deubiquitination stabilizing FZD8 protein and ALKBH1-mediated m7G mRNA methylation suppressing the FZD8/β-catenin axis.

   Evidence Co-IP/GST pull-down with ubiquitination assays and rescue in chondrocytes; RIP-seq and m7G-MeRIP-qPCR with in vivo doxorubicin chemosensitivity in osteosarcoma

   PMID:40318610 PMID:41274478

   Open questions at the time

   • Direct deubiquitination site on FZD8 not mapped
   • Both findings from single labs in distinct disease contexts
9. 2025 Low

   Implicated FZD8 in bone remodeling, with knockout shifting osteoclast/osteoblast balance.

   Evidence CRISPR/Cas9 Fzd8 knockout mouse with histology and RNA-seq DEG analysis (preprint)

   PMID:bio_10.1101_2025.01.19.633799

   Open questions at the time

   • Single preprint, no replication
   • Pathway placement (Fzd10, RANK, Itgb3) inferred from DEG analysis, not mechanistically validated

• How FZD8 ligand selectivity, co-receptor engagement, and Dishevelled coupling produce context-specific outputs in development versus cancer remains unresolved.
• No direct mapping of which Wnt ligands activate FZD8 in each setting
• Mechanism distinguishing developmental cell-cycle control from oncogenic invasion not defined