Mentor Name: Andrew Hong

SMARCB1 is a core component of the SWI/SNF chromatin remodeling complex, where it primarily regulates chromatin at enhancers and promoters and functions as a tumor suppressor gene. SMARCB1-deficient cancers such as renal medullary carcinoma (RMC), malignant rhabdoid tumor (MRT), and atypical teratoid rhabdoid tumor (ATRT) are associated with poor clinical outcomes. Initial clinical benefit is often constrained by the emergence of resistance to therapies such as platinums. Cisplatin resistance (CR) has been explored in a limited context in SMARCB1-deficient cancers by assessing intrinsic resistance at diagnosis. However, there is a lack of systematic assessment of how resistance develops from parental (PAR) cell lines. We generated CR cell lines from PAR BT16 (ATRT), G401 (MRT), and CCLF_PEDS0005T (RMC). Through RNA-sequencing across these models, we found the IGF signaling pathway to be altered. As such, we aim to study the role of IGF signaling in these CR cell lines as compared to the PAR cell lines using functional genomics - deletion with CRISPR-Cas9 lentiviral transduction system and overexpression using a pLX307 lentiviral system. Specifically we will look at Pappalysin 1 (PAPPA) being upregulated and Insulin-like growth factor binding protein 3 (IGFBP3) being downregulated. We will approach this by first deleting IGFBP3 in PAR cells via CRISPR-Cas9 lentiviral transduction system. PAR lines will be transduced with 3 unique sgRNAs targeting IGFBP3 along with positive (sgRPS6) and negative (sgLacZ and sgIntergenic) controls. To validate successful deletion of IGFBP3, ICE sequencing, qRT-PCR, and immunoblotting will be performed. In parallel, PAR cell lines will be transduced with a pLX307 lentiviral vector to drive PAPPA overexpression with LacZ overexpression as a control. To then functionally evaluate the consequences of these IGF pathway modifications, cisplatin IC50 dose-response curves, proliferation, migration, and invasion assays will be conducted with IGFBP3-deleted cells and PAPPA-overexpressed cells. We will assess the extent by which this pathway is important in this resistance pathway using IC50 dose-response curves, proliferation, migration, and invasion assays. Overall, this project expands our understanding of the molecular mechanisms that may drive cisplatin resistance in SMARCB1-deficient cancers. Success would have translational implications such as the development of effective biomarkers and identification of therapeutic targets.