Biology subjects

Ronnekleiv-Kelly, S. M.

Publications and source records attributed to Ronnekleiv-Kelly, S. M..

3 recordsLinked to original sources

bioRxiv2023

CDK7 is a Novel Therapeutic Vulnerability in Fibrolamellar Carcinoma

Fibrolamellar carcinoma (FLC) is a rare and lethal cancer that afflicts young individuals. The tumor arises in the background of a healthy liver, and patients typically present with advanced cancer at the time of diagnosis. Unfortunately, for these patients with advanced or recurrent cancer, no proven systemic therapies exist resulting in only 30-45% of patients surviving to 5 years. Investigations into the molecular underpinning of FLC have revealed a unique gene fusion between heat shock protein 40 (DNAJB1) and the catalytic subunit alpha of protein kinase A (PRKACA), leading to the formation of an oncoprotein (DNAJ-PKAc) that retains kinase activity and is a proven tumor-causing event in FLC. To uncover potential therapeutic targets, we engineered an FLC cell line by introducing the DNAJB1-PRKACA oncogene rearrangement into human hepatocellular cells using CRISPR/Cas9. We identified aberrant cell cycle progression, and follow-up molecular analysis revealed evidence of enhanced cyclin dependent kinase 7 (CDK7) activation in the DNAJB1-PRKACA expressing FLC cells. These findings were confirmed in human samples of FLC. In turn, targeting CDK7 with selective inhibitors demonstrated efficacy in several patient-derived models of FLC, with minimal toxicity to normal liver. Collectively, this work uncovers a novel candidate therapeutic vulnerability in FLC.

cancer biology↗

bioRxiv2022

Chronic Jetlag Accelerates Pancreatic Neoplasia in Conditional Kras-Mutant Mice

Misalignment of the circadian clock compared to environmental cues causes circadian desynchrony, which is pervasive in humans. Clock misalignment can lead to various pathologies including obesity and diabetes, both of which are associated with pancreatic ductal adenocarcinoma - a devastating cancer with an 80% five-year mortality rate. Although circadian desynchrony is associated with an increased risk of several solid-organ cancers, the correlation between clock misalignment and pancreas cancer is unclear. Using a chronic jetlag model, we investigated the impact of clock misalignment on pancreas cancer initiation in mice harboring a pancreas-specific activated Kras mutation. We found that chronic jetlag accelerated the development of pancreatic cancer precursor lesions, with a concomitant increase in precursor lesion grade. Cell-autonomous knock-out of the clock in pancreatic epithelial cells of Kras-mutant mice demonstrated no acceleration of precursor lesion formation, indicating non-cell-autonomous clock dysfunction was responsible for the expedited tumor development. Therefore, we applied single-cell RNA sequencing over time and identified fibroblasts as the cell population manifesting the greatest clock-dependent changes, with enrichment of specific cancer-associated fibroblast pathways due to circadian misalignment. Collectively, these results suggest fibroblasts as the putative target of chronic jetlag-induced accelerated pancreas cancer initiation.

cancer biology↗

bioRxiv2022

Pdx1 expression in hematopoietic cells activates Kras-mutation to drive leukemia in KC (Pdx1-Cre ; LSL-KrasG12D/+) mice

BackgroundPdx1 expression in pancreatic lineage cells underlies the utility of the KC mouse model (Pdx1-Cre; LSL-KrasG12D/+) for understanding how KrasG12D-mutation drives formation of pancreas cancer precursor lesions and carcinoma. The highly utilized KC model has a reported mortality rate of about 30%, which has been attributed to pancreas cancer, despite lack of substantive evidence. This study describes a novel cause of the early deaths, in which KC mice develop Kras-driven T-cell acute lymphoblastic leukemia (T-ALL). MethodsKC mice and control mice underwent histopathologic examination including thymus, liver, spleen, bone marrow and pancreas, and immunohistochemistry (IHC) was used to confirm leukemia development. A reporter strain (Ai14) was used to identify location of Pdx1-Cre expression and concomitant mutant-Kras activation, which was confirmed using flow cytometry, IHC, immunofluorescence, mRNA analysis, and bone marrow transplant studies. ResultsPdx1 expression in the hematopoietic compartment of KC mice resulted in Cre-recombinase mediated excision of lox-stop and activation of mutant-Kras gene (KrasG12D/+) in the multipotent progenitor cells (MPP), and subsequent development of Kras-mutant T-ALL creating thymic tumors in a subset of mice. Overall, 20% (5/25) of KC mice developed a large thymic tumor due to T-ALL by 9 months of age. Moreover, through isolation and transplantation of pooled bone marrow from KC mice into CD45 congenic mice, 100% of recipient mice were found to develop T-ALL. These results further confirm mutant-Kras expression in the hematologic compartment is driving the development of T-ALL in the KC mouse model. ConclusionsThese results are an essential consideration for investigators while utilizing this model in pancreas cancer studies, particularly when evaluating factors that may coincidentally enhance the formation of KrasG12D-driven T-ALL (e.g. transcription factors impacting hematopoietic cells). Finally, the lower penetrance of T-ALL development in KC mice (compared to existing leukemia models) suggest that the KC mouse could be considered as an alternative research model to evaluate onset and factors that exacerbate development of T-ALL.

cancer biology↗