Biology subjects

Linehan, D.

Publications and source records attributed to Linehan, D..

4 recordsLinked to original sources

bioRxiv2025

Improving SBRT by re-wiring immunosuppressive neutrophils in murine pancreatic ductal adenocarcinoma

Radiation is used to treat pancreatic ductal adenocarcinoma (PDAC) in the locally-advanced setting. Stereotactic body radiation therapy (SBRT), in particular, has shown improved outcomes against conventional RT in a number of clinical trials. One key cell type involved in the response to RT are neutrophils. These innate immune cells are the first responders to tissue damage and infiltrate irradiated tumors in high numbers to rectify injury. Neutrophils typically possess an immunosuppressive, wound healing phenotype in this scenario, which allows the tumor to recover and actively suppress immunological efforts to eradicate the disease. Here, we aimed to elucidate the role of neutrophils in a murine model of PDAC treated with SBRT. Mice harboring PDAC tumors were treated with targeted SBRT and neutrophils were determined to be significantly increased in the tissue when compared to unirradiated controls. Additionally, phenotypic analysis determined that these cells were largely immunosuppressive and depletion studies confirmed they played a key role in acquired radioresistance in our model. In order to establish whether these infiltrating cells could be re-wired to contribute to anti-tumor immunity, we utilized a novel combination therapy consisting of SBRT and microspheres containing recombinant IL-12 to attempt to repolarize these cells. Transcriptomic analysis confirmed intratumoral neutrophils underwent considerable changes indicative of an immunostimulatory, anti-tumor phenotype following treatment. Moreover, depleting these cells resulted in a loss of treatment efficacy, suggesting that neutrophil re-wiring was vital for the therapeutic outcome. This study highlights neutrophils as key players in SBRT and IL-12 treatment and confirms they can act as a double-edged sword depending on the treatment employed.

immunology↗

bioRxiv2023

Local Delivery of SBRT and IL12 by mRNA Technology Overcomes Immunosuppressive Barriers to Eliminate Pancreatic Cancer

The immunosuppressive milieu in pancreatic cancer (PC) is a significant hurdle to treatments, resulting in survival statistics that have barely changed in 5 decades. Here we present a combination treatment consisting of stereotactic body radiation therapy (SBRT) and IL-12 mRNA lipid nanoparticles delivered directly to pancreatic murine tumors. This treatment was effective against primary and metastatic models, achieving cures in both settings. IL-12 protein concentrations were transient and localized primarily to the tumor. Depleting CD4 and CD8 T cells abrogated treatment efficacy, confirming they were essential to treatment response. Single cell RNA sequencing from SBRT/IL-12 mRNA treated tumors demonstrated not only a complete loss of T cell exhaustion, but also an abundance of highly proliferative and effector T cell subtypes. SBRT elicited T cell receptor clonal expansion, whereas IL-12 licensed these cells with effector function. This is the first report demonstrating the utility of SBRT and IL-12 mRNA in PC. Statement of significanceThis study demonstrates the use of a novel combination treatment consisting of radiation and immunotherapy in murine pancreatic tumors. This treatment could effectively treat local and metastatic disease, suggesting it may have the potential to treat a cancer that has not seen a meaningful increase in survival in 5 decades.

cancer biology↗

bioRxiv2020

Dual Energy X-ray Absorptiometry (DEXA) as a Longitudinal Outcome Measure of Cancer-Related Muscle Wasting in Mice

IntroductionPancreatic ductal adenocarcinoma (PDAC) is notorious for its associated skeletal muscle wasting (SMW) and mortality. Currently, the relationships between PDAC, SMW, and survival are poorly understood. Thus, there is a great need for a faithful small animal model with a quantitative longitudinal outcome measure that recapitulates clinical PDAC, to define SMW onset and assess progression. Therefore, we aimed to validate dual energy X-ray absorptiometry (DEXA) as a longitudinal outcome of lean body mass, and demonstrate its utility to quantify SMW in the KCKO murine model of PDAC. MethodsIn vivo body composition of: 1) untreated mice at 5, 8, 12, 18, and 22 weeks of age (n=4), and 2) a cohort of mice with (n=20) and without PDAC (n=10), was determined via DEXA, and lean mass of the lower hind limbs was predicted via a region of interest analysis by two independent observers. Total body weight was determined. Tibialis anterior (TA) muscles were weighed and processed for histomorphometry immediately post-mortem. Statistical differences between groups were assessed using t-tests and ANOVA. Linear regression models and correlation analysis were used to measure the association between TA and DEXA mass, and reproducibility of DEXA was quantified via the intraclass correlation coefficient (ICC). ResultsLean mass in growing untreated mice determined by DEXA correlated with TA mass (r2 = 0.94; p <0.0001) and body weight (r2 = 0.89; p <0.0001). DEXA measurements were highly reproducible between observers (ICC = 0.95; 95% CI: 0.89-0.98). DEXA and TA mass also correlated in the PDAC cohort (r2 = 0.76; p <0.0001). Significant SMW in tumor-bearing mice was detected within 38 days of implantation by DEXA, TA mass, and histomorphometry. ConclusionsDEXA is a longitudinal outcome measure of lower limb lean mass in mice. The KCKO syngeneic model is a bona fide model of PDAC-associated SMW that can be quantified with longitudinal DEXA.

cancer biology↗

bioRxiv2020

Septins disruption controls tumor growth and enhances efficacy of Herceptin

Septin expressions are altered in cancer cells and exhibit poor prognoses in malignancies. As the first approach to develop a septin filament targeting agent, we optimized the structure of Forchlorfenuron (FCF), a known plant cytokinin to generate UR214-9, which contrary to FCF, causes septin-2/9 filamental structural catastrophe in cancer cells without altering cellular septin protein levels. In-silico docking using septin-2/septin-2 dimer complex showed that UR214-9 displaced the guanine carbonyl oxygen from the GDP binding domain and showed increased binding energy than FCF(-8.59vs-7.21). UR214-9 reduced cancer cell growth, downregulated HER2/STAT-3 axis and controlled growth of HER2+ pancreatic, breast and ovarian cancer xenografts in NSG mice and enhanced response of Herceptin against HER2+breast cancer xenograft. Transcriptome analysis of UR214-9 exposed cells demonstrated significant perturbation of <20 genes compared to afatinib which impacted >1200 genes in JIMT-1 breast cancer cells indicating target specificity and non-transcriptional functions of UR214-9. In summary, disrupting septins via UR214-9 is a new approach to control the growth of HER2+ malignancies.

cancer biology↗