The functional landscape of patient derived RNF43 mutations predicts Wnt inhibitor sensitivity
2020
A subset of Wnt-addicted cancers are sensitive to targeted therapies that block Wnt secretion or receptor engagement. RNF43 loss-of-function mutations that increase cell surface Wnt receptor abundance cause sensitivity to Wnt inhibitors. However, it is not clear which of the clinically identified RNF43 mutations affect its function in vivo. We assayed 90 missense and 45 truncating RNF43 mutations found in human cancers, using a combination of cell-based reporter assays, genome editing, flow cytometry and immunofluorescence microscopy. Patent-derived xenograft (PDX) models with C-terminal truncating RNF43 mutations were tested for Wnt inhibitor sensitivity. We find that five common germline variants of RNF43 have wild-type activity. The majority of cancer-associated missense mutations in the RING and PA domains are either loss of function or hyperactivating. Hyperactivating mutants appear to function through formation of inactive dimers with endogenous RNF43 and/or ZNRF3. C-terminal truncation mutants including the common G659fs mutant, have discordant behavior in in vitro versus in vivo assays. PDXs and cell lines with C-terminal truncations show increased cell surface FZD, Wnt/β-catenin signaling and are responsive to PORCN inhibition in vivo, providing clear evidence of RNF43 loss of function. In conclusion, RNF43 nonsense and frameshift mutations, including those in the C-terminal domain, and specific missense mutations in RING and PA are loss of function and predict response to upstream Wnt inhibitors in microsatellite stable cancers. This study expands the landscape of actionable RNF43 mutations, potentially extending the benefit of these therapies to additional patients.
Keywords:
- Correction
- Source
- Cite
- Save
- Machine Reading By IdeaReader
44
References
0
Citations
NaN
KQI