Biology subjects

Rust, A. G.

Publications and source records attributed to Rust, A. G..

3 recordsLinked to original sources

bioRxiv2026

A single chromosome 3p break initiates clear cell renal cell carcinoma evolution

Clear cell renal cell carcinoma (ccRCC) is initiated by chromosome 3p loss, yet chromosome losses impose a profound fitness burden on normal cells. How renal epithelial cells tolerate this deleterious aneuploidy during early tumorigenesis remains unclear. Analysis of 949 ccRCC genomes reveals two major classes of chromosome 3p alterations: simple deletions and complex rearrangements surrounding a terminal breakpoint - a pattern we term breakpoint-confined chromothripsis. We modeled both alterations in non-transformed human renal proximal tubule epithelial cells by introducing a single DNA double-strand break on chromosome 3p. Despite an initial fitness disadvantage, chromosome 3p loss drives adaptive genomic evolution that recapitulates recurrent ccRCC-associated aneuploidies, including 5q gain and 14q loss. These alterations alleviate the fitness constraints of 3p loss and promote metabolic reprogramming, clonal expansion, and malignant transformation, producing tumors with features of ccRCC. Thus, a single chromosome break initiates the evolutionary trajectory of ccRCC by creating a fitness bottleneck that selects for recurrent aneuploidies.

cancer biology↗

bioRxiv2026

Murine osteosarcoma recapitulates the driver landscape and genomic complexity of osteosarcoma evolution in humans

Osteosarcoma (OS) genomes are characterized by complex genomic rearrangements (CGRs) that drive genomic instability and clonal diversification early in tumor evolution. As a result, OS tumors display high inter-patient variability, which has hindered molecular stratification and targeted therapeutic development. To study genomic complexity in OS and credential a genetically engineered mouse model of the disease (Sp7-Cre Trp53fl Rb1fl), we performed high-depth and multi-region whole genome sequencing (WGS) of 35 tumor samples from 24 mice. Similar to human OS, the murine OS tumors (mOS) had a high number of somatic structural variants (158 per tumor) with low tumor mutational burden of single nucleotide variants (0.87 mutations/MB). CGRs were identified in 63% (15/24) of mOS cases, most frequently affecting chromosome 15 (33%, 8/24 mice) and resulting in Myc amplification in 6 mice, ranging from 5 to 104 copies. Myc amplification was verified with DNA FISH, long-read sequencing and gene expression data, which revealed examples of Myc amplification in both extrachromosomal circular DNA (ecDNA) and in derivative chromosomes generated by CGRs. PTEN loss occurred frequently (59% 12/22 mice), and contributed to osteosarcomagenesis, as demonstrated by tumor initiation with in vivo CRISPR/Cas9-mediated deletion experiments (2 mice). Together, these results demonstrate that a preclinical model of osteosarcoma can generate the genomic heterogeneity and complexity of the human disease, thereby facilitating research into mechanisms of tumor initiation and drivers of progression and relapse.

cancer biology↗

bioRxiv2022

"Transposon Mutagenesis Reveals RBMS3 as a Promoter of Malignant Progression of BRAFV600E-Driven Lung Tumorigenesis."

Mutationally-activated BRAFV600E is detected in ~2% of all human non-small cell lung cancers (NSCLC), and serves as a predictive biomarker for treatment of patients with FDA-approved pathway-targeted therapies that inhibit signaling by the BRAFV600E oncoprotein kinase. In genetically engineered mouse (GEM) models, expression of BRAFV600E in alveolar type 2 (AT2) pneumocytes initiates the development of benign lung tumors that, without additional genetic alterations, rarely progress to malignant lung adenocarcinomas. To identify genes that might cooperate with BRAFV600E for malignant lung cancer progression we employed Sleeping Beauty (SB)-mediated transposon mutagenesis, which dramatically accelerated the onset of lethal lung adenocarcinomas. Amongst the diverse group of genes identified by this in vivo screen was Rbms3 (RNA binding motif single-stranded interacting protein 3), an RNA-binding protein implicated as a possible tumor suppressor. Using CRISPR/CAS9 gene editing we confirmed that RBMS3 silencing cooperated with BRAFV600E to promote progression of malignant lung cancer with a distinct micropapillary architecture. Moreover, RBMS3 silencing also cooperated with BRAFV600E to promote the growth of lung organoids in vitro. BRAFV600E/RBMS3Null lung tumors displayed elevated expression of b-catenin (CTNNB1), suggesting that RBMS3 silencing may result in elevated signaling through the WNT>CTNNB1>c-MYC pathway. Finally, analyses of patient samples in The Cancer Genome Atlas (TCGA) revealed that the region of chromosome 3 encompassing RBMS3 is frequently lost in NSCLC and correlates with poor patient prognosis. Collectively, SB-mediated transposon mutagenesis has revealed the ability of a novel tumor suppressor, RBMS3, to cooperate with BRAFV600E to promote lung carcinogenesis, and suggests that RBMS3 silencing may contribute to malignant progression of numerous human lung cancers. SIGNIFICANCEThe BRAFV600E oncoprotein kinase is a potent initiator of benign lung tumorigenesis, but is insufficient to elicit malignant lung adenocarcinoma without additional cooperating alterations. Sleeping Beauty-mediated transposon mutagenesis has revealed a number of genes that cooperate with BRAFV600E to promote lung cancer progression, in particular Rbms3, which encodes an RNA binding protein. Hence, this genetic screen provides a deeper understanding of the molecular mechanisms underlying BRAFV600E-driven lung carcinogenesis, and is an important step improving our ability to successfully target this disease.

cancer biology↗