Sandra Sexton

Dr. Sandra Sexton


Research Focus & Metrics

Academic Career Length

10Years (2017-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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3 February 2022 in Cancer Cell
Verified
Journal Article
Closed access
AAAftab Alam
Aftab Alam
ELEric Levanduski
Eric Levanduski
PDParker Denz
Parker Denz
HVHelena Solleiro Villavicencio
Helena Solleiro Villavicencio
MBMaulasri Bhatta
Maulasri Bhatta
PDPrasenjit Dey
Prasenjit Dey

16 May 2019 in Cancers
Verified
Journal Article
Open access
PDF file
Renuka IyerRenuka Iyer
Renuka Iyer
OMOrla Maguire
Orla Maguire
MKMinhyung Kim
Minhyung Kim
LCLeslie I. Curtin
Leslie I. Curtin
SSSandra Sexton
Sandra Sexton
HMHans Minderman
Hans Minderman
The multikinase inhibitor sorafenib is the only standard first-line therapy for hepatocellular carcinoma (HCC). Here, we report the dose-dependent effects of sorafenib on the immune response, which is related to nuclear factor of activated T cells 1 (NFAT1) activity. In vitro and in vivo experiments were performed with low and high doses of sorafenib using human T cells and spontaneous developed woodchuck HCC models. In vitro studies demonstrated that following exposure to a high dose of sorafenib the baseline activity of NFAT1 in T cells was significantly increased. In a parallel event, high dose sorafenib resulted in a significant decrease in T cell proliferation and increased the proportion of PD-1 expressing CD8+ T cells with NFAT1 activation. In the in vivo model, smaller tumors were detected in the low-dose sorafenib treated group compared to the placebo and high-dose treated groups. The low-dose sorafenib group showed a significant tumor growth delay with significantly more CD3+ cells in tumor. This study demonstrates that sorafenib has immunomodulatory effects in a dose- and time-dependent manner. Higher dose of sorafenib treatment was associated with immunosuppressive action. This observed effect of sorafenib should be taken into consideration in the selection of optimum starting dose for future trials.

3 February 2022 in Animals
Verified
Journal Article
Open access
PDF file
BHBonnie Lee Hylander
Bonnie Lee Hylander
ERElizabeth Repasky
Elizabeth Repasky
SSSandra Sexton
Sandra Sexton
Mice are the most common animal used to study disease, but there are real concerns about the reproducibility of many of these experiments. This review discusses how several different sources of chronic stress can directly impact experimental outcomes. Mandated housing conditions induce an underappreciated level of chronic stress but are not usually considered or reported as part of the experimental design. Since chronic stress plays a critical role in the development and progression of many somatic diseases including cancer, obesity, and auto-immune diseases, this baseline stress can directly affect outcomes of such experiments. To study the role of stress in both physical and psychiatric diseases, there has been a proliferation of protocols for imposing chronic stress on mice. For somatic diseases, biomarkers can be used to compare the models with the disease in patients, but to evaluate the validity of psychiatric models, behavioral tests are carried out to assess changes in behavior and these tests may themselves cause an underappreciated degree of additional stress. Therefore, it is important for animal welfare to reduce baseline stress and select the most humane protocols for inducing and assessing chronic stress to obtain the most reliable outcomes.

8 September 2022 in JCI Insight
Verified
Journal Article
Open access
PDF file
BBBora E. Baysal
Bora E. Baysal
AAAbdulrahman A Alahmari
Abdulrahman A Alahmari
TRTori Christian Rodrick
Tori Christian Rodrick
DTDebra Tabaczynski
Debra Tabaczynski
LCLeslie Curtin
Leslie Curtin
SSSandra Sexton
Sandra Sexton
Increased red cell distribution width (RDW), which measures erythrocyte mean corpuscular volume (MCV) variability (anisocytosis), has been linked to early mortality in many diseases and in older adults through unknown mechanisms. Hypoxic stress has been proposed as a potential mechanism. However, experimental models to investigate the link between increased RDW and reduced survival are lacking. Here, we show that lifelong hypobaric hypoxia (~10% O 2 ) increased erythrocyte numbers, hemoglobin, and RDW, while reducing longevity in male mice. Compound heterozygous knockout (hKO) mutations in succinate dehydrogenase (Sdh; mitochondrial complex II) genes Sdhb , Sdhc , and Sdhd reduced Sdh subunit protein levels, reduced RDW, and increased healthy life span compared with WT mice in chronic hypoxia. RDW-SD, a direct measure of MCV variability, and the SD of MCV showed the most statistically significant reductions in Sdh hKO mice. Tissue metabolomic profiling of 147 common metabolites showed the largest increase in succinate with elevated succinate/fumarate and succinate/oxoglutarate (2-ketoglutarate) ratios in Sdh hKO mice. These results demonstrate that mitochondrial complex II level is an underlying determinant of both RDW and healthy life span in hypoxia and suggest that therapeutic targeting of Sdh might reduce high RDW–associated clinical mortality in hypoxic diseases.

1 February 2023 in Journal of Hepatocellular Carcinoma
Verified
Journal Article
Open access
PDF file
OSOlga Sergeeva
Olga Sergeeva
YZYifan Zhang
Yifan Zhang
SGSongqi Gao
Songqi Gao
ECE Ricky Chan
E Ricky Chan
MSMaxim Sergeev
Maxim Sergeev
ZLZhenghong Lee
Zhenghong Lee
Purpose: We tested a recently developed short peptide radioligand for PET imaging of hepatocellular carcinoma (HCC) by targeting an oncoprotein, extra-domain B fibronectin (EDB-FN) in the tumor microenvironment. Methods: The radioligand consists of a small linear peptide ZD2 with 68Ga-NOTA chelator, and specifically binds to EDB-FN. PET images were acquired dynamically for 1 hour after intravenously (i.v.) injecting 37 MBq (1.0 mCi) of the radioligand into the woodchuck model of naturally occurring HCC. Woodchuck HCC originated from chronic viral hepatitis infection, which recapitulates the corresponding human primary liver cancer. The animals were euthanized post-imaging for tissue collection and validation. Results: For ZD2 avid liver tumors, the radioligand accumulation plateaued a few minutes after injection, while the liver background uptake stabilized 20 min post-injection. The status of EDB-FN in woodchuck HCC was confirmed by histology and validated by PCR and western blocking. Conclusion: We have showed the viability of using the ZD2 short peptide radioligand targeting EDB-FN in liver tumor tissue for PET imaging of HCC, which can potentially impact the clinical care for HCC patients.

21 August 2023 in Cells
Verified
Journal Article
Open access
PDF file
MYMatthew Yehl
Matthew Yehl
DKDominik Kucharski
Dominik Kucharski
MEMichelle Eubank
Michelle Eubank
BGBrandon Gulledge
Brandon Gulledge
GRGamal Rayan
Gamal Rayan
SZShoshanna N. Zucker
Shoshanna N. Zucker
Although melanoma accounts for only 5.3% of skin cancer, it results in >75% of skin-cancer-related deaths. To avoid disfiguring surgeries on the head and neck associated with surgical excision, there is a clear unmet need for other strategies to selectively remove cutaneous melanoma lesions. Mohs surgery is the current treatment for cutaneous melanoma lesions and squamous and basal cell carcinoma. While Mohs surgery is an effective way to remove melanomas in situ, normal tissue is also excised to achieve histologically negative margins. This paper describes a novel combination therapy of nonthermal plasma (NTP) which emits a multitude of reactive oxygen species (ROS) and the injection of a pharmaceutical agent. We have shown that the effects of NTP are augmented by the DNA-damaging prodrug, tirapazamine (TPZ), which becomes a free radical only in conditions of hypoxemia, which is often enhanced in the tumor microenvironment. In this study, we demonstrate the efficacy of the combination therapy through experiments with B16-F10 and 1205 Lu metastatic melanoma cells both in vitro and in vivo. We also show the safety parameters of the therapy with no significant effects of the therapy when applied to porcine skin. We show the need for the intratumor delivery of TPZ in combination with the surface treatment of NTP and present a model of a medical device to deliver this combination therapy. The importance of functional gap junctions is indicated as a mechanism to promote the therapeutic effect. Collectively, the data support a novel therapeutic combination to treat melanoma and the development of a medical device to deliver the treatment in situ.