In vivo functional classification of PTEN variants reveals context-dependent oncogenicity and interindividual variability

Gene variants, secondary mutations, and stochastic individual variability complicate cancer diagnosis, prognosis, and treatments. Here, we systematically assess the functional impact of PTEN cancer-related missense mutations in mammalian cell lines, yeast, and Caenorhabditis elegans. While cell-based assays revealed alterations in lipid phosphatase activity, CRISPR-based engineering of orthologous mutations in C. elegans enabled classification of variants based on organismal phenotypes and transcriptional profiles, providing a rapid framework to predict oncogenic potential. We further show that secondary mutations, such as gain-of-function of cdc-25.1/CDC25A, can enhance the phenotypic impact of specific daf-18/PTEN variants, revealing context-dependent oncogenicity. Finally, single-worm transcriptomic analyses uncovered substantial interindividual variability among isogenic animals with identical cdc-25.1 and daf-18 mutations, linking transcriptional states to divergent phenotypic outcomes. Together, our results establish C. elegans as a powerful in vivo platform to integrate genetic, functional, and transcriptional information for the interpretation of cancer-associated variants.