Biology subjects

Oberg, A. L.

Publications and source records attributed to Oberg, A. L..

4 recordsLinked to original sources

bioRxiv2026

Nuclear Cathepsin L Remodels the Replication Machinery to Create a Therapeutic Vulnerability in Ovarian Cancer

Abstract Therapeutic resistance in ovarian cancer is frequently driven by persistent replication stress, yet the molecular mechanisms that convert replication stress into a therapeutically exploitable vulnerability remain incompletely understood. Here, we identify drug-induced nuclear cathepsin L (nCTSL) as a previously unrecognized regulator of replication stress and DNA repair. Clofarabine (CLF) combined with the ATR inhibitor AZD6738, or the CHK1 inhibitor prexasertib promoted nuclear accumulation of CTSL, where it remodeled the replication machinery through degradation of CCNE1, MCM3, MCM6, and geminin, accompanied by loss of RAD51 and 53BP1 and increased {gamma}H2AX and phospho-RPA2. DNA fiber analysis demonstrated marked inhibition of replication fork progression following CLF-based combinations, whereas CTSL depletion accelerated fork progression and abolished therapy-induced replication stress. Reconstitution with the nuclear M1F CTSL isoform restored replication restraint, confirming a direct role for nuclear CTSL in regulating replication dynamics. GFP-based DNA repair reporter assays further revealed that CLF-based combinations suppress DNA repair competence in a CTSL-dependent manner, indicating that nuclear CTSL couples replication stress amplification with functional inhibition of repair pathways. Functionally, CLF-based combinations selectively targeted transformed fallopian tube secretory epithelial cells while sparing non-transformed counterparts, demonstrated broad activity in patient-derived ovarian cancer ascites spheroids, and significantly inhibited tumor growth and prolonged survival in vivo. Collectively, our findings identify nuclear CTSL as a mechanistic driver of replication stress that remodels the replication machinery, impairs DNA repair, and creates a therapeutically exploitable vulnerability in ovarian cancer. We propose that nuclear CTSL promotes a transition from replication competence to replication catastrophe, thereby establishing a conceptual framework for biomarker-guided therapeutic strategies targeting CTSL-dependent replication stress.

cancer biology↗

bioRxiv2025

Role of drug induced nuclear CTSL (nCTSL) in DNA damage response in cancer- therapeutic implications

ABSTRACT Background: Despite treatment advances, ovarian cancer (OC) remains the deadliest gynecological cancer, with a ~70% mortality rate. OCs initially respond to platinum chemotherapy but often develop resistance. While PARP inhibitors improve relapse-free survival in responsive cases, they do not extend overall survival. This underscores the need for effective combination therapies beyond BRCA status. The lysosomal protein cathepsin L (CTSL) can traffic to the nucleus, where it can regulate DNA repair and serve as a chromatin modifier. Here, we tested the hypothesis that nucleoside analog clofarabine (CLF) induced nuclear CTSL (nCTSL) serves as a biomarker of sensitivity to DNA-damaging agents in ovarian cancer. Methods: Role of nuclear CTSL in DNA damage, synergy with PARPis and CRM1 inhibitor, tumor regression was analyzed by 3D-spheroid culture, colony forming assay, subcellular fractions, comet assay, and IFC/ western-blotting using PARP inhibitor-sensitive and -resistant OC cell lines, ex vivo cultures of patient-derived OC ascites cells (OVA), primary OCs, and patient-derived xenografts (PDXs). Results: In OC cell lines, treatment with CLF induced nCTSL in a subset of models-designated CLF-responsive (CLF-r)-and sensitized them to the PARP inhibitors olaparib and rucaparib. In CLF-non-responsive (CLF-nr) models, nCTSL trafficking and drug synergy were achieved with the CLF+olaparib combination. Synergy was observed in 47% of CLF-r and 24% of CLF-nr OVA samples. Mechanistically, CLF monotherapy induced nuclear import of CTSL via KPNB1 in CLF-r cells, while combination treatment with CLF+olaparib was required in CLF-nr cells. CLF also downregulated the nuclear export protein CRM1 in both CLF-r and CLF-nr models. CTSL knockdown conferred resistance to CLF+olaparib in both cohorts, supporting a functional role for nCTSL in therapeutic response. Notably, in a subset of OVAs (29%) classified as CLF-resistant (CLF-Res), CLF failed to downregulate CRM1; however, pharmacological inhibition of CRM1 with KPT8602 restored sensitivity to CLF+PARP inhibitor treatment. In vivo, CLF+olaparib treatment in CLF-r and CLF-nr PDX models led to enhanced DNA damage, reduced tumor burden, and prolonged survival. Conclusion: Collectively, these findings identify nCTSL as a predictive marker of response to DNA-damaging therapies and support the CLF+olaparib combination as a promising strategy for overcoming drug resistance in OC via CTSL-mediated DNA damage.

cancer biology↗

bioRxiv2020

Nuclear GSK-3β and Oncogenic KRas Promote Expansion of Terminal Duct Cells and the Development of Intraductal Papillary Mucinous Neoplasm

Intraductal papillary mucinous neoplasm (IPMN) represents one type of pancreatic ductal adenocarcinoma (PDA) precursor lesion, however its cell-of-origin remains unclear. Here we describe a new mouse model in which pancreas-specific Cre activation of a nuclear glycogen synthase kinase-3{beta} transgene is combined with oncogenic KRas (referred to as KNGC). KNGC mice show accumulation of neoplastic ductal cells at 4-weeks that progressively develop into IPMN with low-grade dysplasia in advanced age. RNA-sequencing identified expression of several terminal duct cell lineage genes including Agr2 and Aqp5. Interestingly, Aqp5, a water channel, was found to be required for the development of IPMN lesions in KNGC mice. Staining of human IPMN samples indicates that these preneoplastic lesions also arise from expansion of the terminal duct population. Altogether, these data highlight the utility of the KNGC model for understanding the biology of IPMN and potential utility in defining predictive biomarkers of IPMN - PDA development. Statement of significanceUnderstanding the cell-of-origin of IPMN is crucial to developing early detection methods that specifically target aggressive precursors of PDA. This work, using a novel mouse model, identifies Aqp5-modulated development of Agr2+ terminal ducts that could potentially serve as a clinical biomarker for IPMN.

cancer biology↗

bioRxiv2020

Polymorphisms in STING affect human innate immune responses to poxviruses

We conducted a large genome-wide association study (GWAS) of the immune responses to primary smallpox vaccination in a combined cohort of > 1,600 subjects. We identified a cluster of SNPs on chromosome 5 (5q31.2) that were significantly associated (p-value: 1.3 x 10-12 - 1.5x10-36) with IFN response to in vitro poxvirus stimulation. Examination of these SNPs led to the functional testing of rs1131769, a non-synonymous SNP in TMEM173 causing an Arg-to-His change at position 232 in the STING protein--a major regulator of innate immune responses to viral infections. Our findings demonstrate important functional differences between the two alleles, where the major allele (R232) more effectively induces IFN secretion. Molecular modeling of both alleles identified altered ligand binding characteristics between the two variants, providing a potential mechanism underlying differences in inter-individual responses to poxvirus vaccination. Our data demonstrate that possession of the H232 variant impairs STING-mediated innate immunity to poxviruses. These results clarify prior studies evaluating functional effects of genetic variants in TMEM173 and provide novel data regarding genetic control of poxvirus immunity. Contribution to the FieldHere we report that a single nucleotide non-synonymous polymorphism in the TMEM173 gene encodes for a STING variant conferring a reduced IFN stimulated response compared to wild type. Our results suggest that, upon binding of the STING H232 variant to its ligand, activation of downstream signaling proteins is impaired, resulting in decreased production of IFN and a weaker interferon-stimulated gene response. Molecular modeling indicates that the diminished functional activity of this variant is likely due to an altered physical structure of the STING protein. STING controls the innate, type I IFN response to double-stranded DNA and cyclic dinucleotides. Individuals with the H232 variant of STING have a much weaker innate immune response to vaccinia virus. Our data help resolve ongoing controversies regarding the role of genetic variants in STING function. Because STING plays an important role in our immune response to DNA viruses and bacteria, our results can be used to predict who will and will not respond to vaccines and treatments, and to design more effective vaccine candidates. Given the role of the STING protein in innate responses to DNA viruses and bacterial pathogens, these data may also be useful in developing novel treatment options for multiple infectious diseases.

immunology↗