Browsing by Author "Powers, Elizabeth"

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    APC Loss Prevents Doxorubicin-Induced Cell Death by Increasing Drug Efflux and a Chemoresistant Cell Population in Breast Cancer
    (MDPI, 2023-04-21) Stefanski, Casey D.; Arnason, Anne; Maloney, Sara; Kotsen, Janna; Powers, Elizabeth; Zhang, Jian-Ting; Prosperi, Jenifer R.; Biochemistry and Molecular Biology, School of Medicine
    Chemoresistance is a major health concern affecting cancer patients. Resistance is multifactorial, with one mechanism being the increased expression of ABC transporters (such as MDR1 and MRP1), which are drug efflux transporters capable of preventing intracellular accumulation of drugs and cell death. Our lab showed that the loss of Adenomatous Polyposis Coli (APC) caused an intrinsic resistance to doxorubicin (DOX), potentially through an enhanced tumor-initiating cell (TIC) population and the increased activation of STAT3 mediating the expression of MDR1 in the absence of WNT being activated. Here, in primary mouse mammary tumor cells, the loss of APC decreased the accumulation of DOX while increasing the protein levels of MDR1 and MRP1. We demonstrated decreased APC mRNA and protein levels in breast cancer patients compared with normal tissue. Using patient samples and a panel of human breast cancer cell lines, we found no significant trend between APC and either MDR1 or MRP1. Since the protein expression patterns did not show a correlation between the ABC transporters and the expression of APC, we evaluated the drug transporter activity. In mouse mammary tumor cells, the pharmacological inhibition or genetic silencing of MDR1 or MRP1, respectively, decreased the TIC population and increased DOX-induced apoptosis, supporting the use of ABC transporter inhibitors as therapeutic targets in APC-deficient tumors.
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    Prescription of Panoramic Radiographs in Children: A Health Services Assessment of Current Guidelines
    (American Academy of Pediatric Dentistry, 2017) Yepes, Juan F.; Powers, Elizabeth; Downey, Tim; Eckert, George J.; Tang, Qing; Vinson, LaQuia; Maupomé, Gerardo; Pediatric Dentistry, School of Dentistry
    Purpose: To (1) determine adherence to guidelines when prescribing panoramic radiographs (PR) for patients 18 y.o. and younger; and 2) compare PR prescriptions between general dentists (GPs) and pediatric dentists (PDs). Methods: A retrospective analysis of insurance claims included codes for PRs and associated codes for two cities between 2008 and 2015. Chi-square tests ascertained the likelihood of a PR being associated within three days of routine exams. Results: A total of 81,699 pediatric patients were seen by 2,077 GPs and 103 PDs. There were 11,993 PRs, 119,068 routine exams (7,343 associated with a PR), 13,819 orthodontic procedures (378 associated with a PR), 798 third molar procedures (172 associated with a PR), and 16,636 procedures for acute problems (1,670 associated with a PR). Patients aged eight years old and younger had the largest discrepancy between GPs and PDs. GPs prescribed proportionally more films in patients five years old and younger, but PDs prescribed more in seven and eight year olds. Nine- to 18 year olds. had more similar patterns between GPs and PDs, except for 14- to 15 year olds, when GPs prescribed more. Conclusions: GPs prescribed PR in patients younger than five years old more often and were somewhat less likely to follow guidelines.