Ruyi Zhang

RNF43 is best known for removing the Wnt-receptor complex from the cell surface, thereby maintaining Wnt-signaling at minimal essential levels. Recent studies reported that RNF43-mutant colorectal cancers carrying the common BRAFV600E mutation, respond more effectively to combined BRAF/EGFR inhibition. To determine whether RNF43 directly regulates EGFR or BRAF protein abundance, multiple pancreatic and colorectal cancer cell line models were generated in which RNF43 was knocked out, repaired, or stably overexpressed. Total and cell surface EGFR levels, as well as endogenous BRAF expression, were quantified. Across all models, no consistent evidence emerges that RNF43 modulates endogenous EGFR or BRAF levels. R-spondins likewise fail to alter EGFR levels or internalization. Notably, elevated EGFR expression observed in a subset of RNF43 knockout clones is induced by unintended CRISPR/Cas9 vector integration rather than the absence of RNF43 itself, highlighting a previously underappreciated artefact that can confound interpretations of EGFR regulation in genome edited lines. Overall, the data argue against a direct and general role for RNF43 in controlling EGFR or BRAF protein abundance, contradicting recent reports that propose degradation of these targets. Further studies are required to resolve these discrepancies and clarify the mechanistic basis underlying these conflicting observations.

Bidens pilosa L., a traditional Chinese medicinal herb, has been used in clinical practice for the treatment of inflammatory diseases and cancer. BPA, an extract derived from the whole herb of B. pilosa L., has been shown to possess potent immunomodulatory properties by regulating tumor-associated macrophages (TAMs) and regulatory T cells (Tregs) within the tumor microenvironment (TME) in a mouse syngeneic colorectal cancer (CRC) model. RT-PCR and flow cytometry analyses showed that BPA, together with its flavonoid and polyacetylene constituents, effectively suppressed the differentiation of M2-TAMs and Tregs by downregulating Arg-1 and CD25 expression. They had minimal effects on the expression of markers associated with M1-TAMs and promoted the proliferation of CD4⁺ T cells that were inhibited by M2-TAMs and Tregs. In mice, BPA markedly inhibited the growth of syngeneic CRC tumors, accompanied by decreased serum levels of the immunosuppressive cytokine IL-10 and reduced expression of the proliferative marker Ki67 in tumor tissues. Moreover, BPA downregulated the mRNA expression of markers associated with M2-TAMs and Tregs, while increasing markers associated with M1-TAMs. Western blot analyses of tumor tissues revealed that BPA reduced the expression of marker proteins associated with M2-TAMs and Tregs, while increasing the expression of the immune-stimulatory markers CD80, GITR and CD4. In addition, combined treatment with BPA and 5-fluorouracil (5-FU), a commonly used chemotherapeutic agent for CRC, notably enhanced the anti-tumor effect in mice. These findings indicate that BPA, an active extract of B. pilosa L., showed antitumor activity in mice by suppressing the differentiation of pro-tumorigenic TAMs and Tregs within the TME.

The AXIN1 mutation landscape for various cancer types

Strong AXIN1 missense variants induce liver tumor formation in mice

Side-by-side comparison of selected AXIN1 variants in different domains

Additional analysis of missense variants near the GSK3β domain

AlphaFold structure prediction for human AXIN1

Analysis of evolutionary conserved AXIN1 residues using the ConSurf tool.