Project Summary In contrast to other tumor suppressors, 75% of p53 alterations in human cancers are missense mutations in the DNA-binding domain that generate abnormally stabilized mutant proteins (‘mutp53’). The research program of Unit Director Dr. Ute Moll’s laboratory generated new mouse models that definitively proved that certain hotspot missense mutant p53 proteins not only lose their tumor suppressor function, but acquire broad oncogenic gain- of-function (GOF) activities (‘mutp53GOF’). Our humanized p53R248Q knockin mice (’Q’ mice) provided the long-sought compelling phenotype of faster onset of all spontaneously arising tumor types and significantly shorter survival compared to p53null littermates. Importantly, our finding translates to human cancers. In Li- Fraumeni patients harboring p53 germline mutations, the Q allele dramatically accelerates tumor onset by 10.5 years and leads to increased mortality compared to p53null-like Li-Fraumeni patients. Moreover, TCGA data suggest that sporadic cancer patients harboring specific GOF alleles have higher death rates than patients with p53 mutations that are functionally null. GOF contributes to malignant progression with increased proliferation, invasion, metastasis, chemoresistance, stroma remodeling and reprogrammed metabolism. As central translational progress, our lab also established that these mice develop strong exploitable dependency on continued high expression of mutp53 for tumor growth, maintenance and metastasis. We showed that genetic or pharmacologic (via Hsp90 inhibitors) ablation of mutp53 in autochthonous lymphomas and colorectal cancers triggers strong cytotoxicity in different hotspot GOF knockin mice, translating to tumor regression, inhibition of invasion and major gains in survival, even in the absence of wildtype p53. My research builds on these strong pre-clinical and clinical findings to further explore mutp53GOF and its exploitability in a broader cancer context. Given the exceptionally high frequency of TP53 mutations across all cancer types, this therapeutic concept is highly relevant for a wide population of cancer patients. As a research Investigator in the Moll laboratory, I am actively pursuing two areas of research. 1) I have been leading research on evaluating the therapeutic potential of mutp53 ablation in other major sporadic carcinomas by testing autochthonous mouse models of liver and pancreatic cancer. 2) I designed and characterized a new ‘wtp53 to mutp53 switch’ mouse strain and I lead work identifying the molecular basis of mutp53 GOF-driven tumor formation in vivo using time-resolved ChIPseq/single cell RNAseq and functional proteome analyses. My ultimate goal is to identify novel therapeutic targets for mutp53 cancers. In addition to performing bench research to address these biologic and translational questions, my responsibilities include training of postdocs, graduate and undergraduate students; technology development for the group and oversight...