Biology subjects

Xu, E. S.

Publications and source records attributed to Xu, E. S..

4 recordsLinked to original sources

bioRxiv2025

Differential Impact of Lymphocytes on Radiation Response in Autochthonous versus Transplant Sarcomas in Syngeneic Mice

Preclinical studies in transplant tumor models showing high cure rates with combined radiotherapy (RT) and immunotherapy have rarely translated to clinical success, and studies in autochthonous tumor models are limited. We hypothesized that lymphocytes differentially affect RT response in transplant versus autochthonous tumor models. Here, we compared tumor onset and growth delay after 0 or 20 Gy for autochthonous versus transplant soft tissue sarcomas in Rag2-/- mice lacking an adaptive immune system versus immune-intact Rag2+/- mice. While time to tumor onset did not differ between Rag2-/- and Rag2+/- mice in the autochthonous model, transplant tumor onset was significantly slower in immunocompetent mice. No transplant tumors in Rag2-/- mice or autochthonous tumors were cured by RT, whereas 30.4% of Rag2+/- mice with transplant tumors were cured. These results highlight the importance of including autochthonous tumors as complementary model systems to study the interplay between the immune system and RT response.

cancer biology↗

bioRxiv2023

Mis-splicing Drives Loss of Function of p53E224D Point Mutation

BackgroundTp53 is the most commonly mutated gene in cancer. Canonical Tp53 DNA damage response pathways are well characterized and classically thought to underlie the tumor suppressive effect of Tp53. Challenging this dogma, mouse models have revealed that p53 driven apoptosis and cell cycle arrest are dispensable for tumor suppression. Here, we investigated the inverse context of a p53 mutation predicted to drive expression of canonical targets, but is detected in human cancer. MethodsWe established a novel mouse model with a single base pair mutation (GAG>GAC, p53E221D) in the DNA-Binding domain that has wild-type function in screening assays, but is paradoxically found in human cancer in Li-Fraumeni syndrome. Using mouse p53E221D and the analogous human p53E224D mutant, we evaluated expression, transcriptional activation, and tumor suppression in vitro and in vivo. ResultsExpression of human p53E224D from cDNA translated to a fully functional p53 protein. However, p53E221D/E221D RNA transcribed from the endogenous locus is mis-spliced resulting in nonsense mediated decay. Moreover, fibroblasts derived from p53E221D/E221D mice do not express a detectable protein product. Mice homozygous for p53E221D exhibited increased tumor penetrance and decreased life expectancy compared to p53 WT animals. ConclusionsMouse p53E221D and human p53E224D mutations lead to splice variation and a biologically relevant p53 loss of function in vitro and in vivo.

genomics↗

bioRxiv2020

A single cell atlas reveals distinct immune landscapes in transplant and primary tumors that determine response or resistance to immunotherapy

Despite impressive responses in some patients, immunotherapy fails to cure most cancer patients. Preclinical studies indicate that radiotherapy synergizes with immunotherapy, promoting radiation-induced antitumor immunity. Nearly all preclinical immunotherapy studies utilize transplant tumor models, but cure rates of transplant tumor models treated with immunotherapy often overestimate patient responses. Here, we show that transplant tumors are cured by PD-1 blockade and radiotherapy, but identical treatment fails in autochthonous tumors. We generated a single-cell atlas of tumor-infiltrating immune cells from transplant and primary tumors treated with radiation and immunotherapy, which reveals striking differences in their immune landscapes. Although radiotherapy remodels myeloid cell phenotypes in primary and transplant tumors, only transplant tumors are enriched for CD8+ T cells that mediate tumor clearance while mice with primary sarcomas demonstrate tumor-specific tolerance. These results identify distinct microenvironments in tumors that coevolve with the immune system, which promote tolerance that must be overcome for immune-mediated cancer cures.

cancer biology↗

bioRxiv2020

Disruption of oncogenic targeting by ISWI via phosphorylation of a prion-like domain

Chromosomal translocations generate oncogenic fusion proteins in approximately one-third of sarcomas, but how these proteins promote tumorigenesis and the effect of cancer therapies on their function are not well understood. Here, we reveal a molecular mechanism by which the fusion oncoprotein FUS-CHOP promotes tumor maintenance that also explains the remarkable radiation sensitivity of myxoid liposarcomas. We identified novel interactions between FUS-CHOP and chromatin remodeling complexes that regulate sarcoma cell proliferation. One of these chromatin remodelers, SNF2H, co-localizes with FUS-CHOP genome-wide at active enhancers. Following ionizing radiation, DNA damage response kinases phosphorylate the prion-like domain of FUS-CHOP to impede these protein-protein interactions, which are required for transformation. Therefore, the DNA damage response after irradiation disrupts oncogenic targeting of chromatin remodelers required for FUS-CHOP-driven sarcomagenesis. SignificancePrion-like domains translocated in cancer have been shown to drive global epigenetic changes that are oncogenic. However, some translocation-driven cancers exhibit dramatic clinical responses to therapy, though the mechanism for these responses are not well-understood. Here we show that ionizing radiation can disrupt oncogenic interactions between a fusion oncoprotein and a chromatin remodeling complex, ISWI. This mechanism of disruption links phosphorylation of the prion-like domain in an oncogenic fusion protein to DNA damage after ionizing radiation and reveals that a dependence on oncogenic chromatin remodeling underlies sensitivity to radiation therapy in myxoid liposarcoma.

cancer biology↗