Introduction: Radiotherapy (RT) is a treatment option for men with Prostate Cancer (PCa). While minimizing damage to proximal healthy tissue, RT can still result in severe toxicities. Studies have shown that exposure to ionizing radiation leads to changes of miRNA expression at the cellular level, making cells more radioresistant or radiosensitive which could result in toxicity, recurrence, and metastatic spread. Importantly, RT induced miRNA changes have been found to be associated with RT response in clinical contexts and may serve as diagnostic tools to assess PCa risk stratification that inform precision medicine approaches. However, miRNAs have not been assessed in patients treated with proton therapy (PT), a type of particle-based RT which purports improved dose distribution and reduced toxicity. This is attributed to the proton’s unique ability to deposit most of its energy at a narrow bragg peak with minimal energy deposition beyond the peak, into surrounding organs. Because miRNAs are ubiquitous in the human body, they are stable in many environments including the bloodstream and are becoming attractive biomarkers of treatment response, including RT. Still, blood-derived biomarkers for diagnosis, prognosis, and therapy response is an emerging field and there remains a lack of standardization and normalization of sample preparation and protocol for isolating human derived miRNA from plasma. The objective is to optimize RNA isolation procedures so that it is achievable to accurately identify miRNA biomarkers in PCa patients undergoing PT. Methods: The results of 2 RNA isolation kits were compared. To assess the effectiveness of each optimization strategy performed, a number of metrics were used to quantitate and determine the quality of the RNA: fluorometry (Qubit 2.0 and 4.0), spectrophotometry (nano-drop), and qRT-PCR amplification (Taqman). Results: Fluorometry methods were not sensitive enough for RNA quantification for either kit. Of the two RNA isolation kits, Kit A outperformed Kit B in every metric output when 100 uL of plasma was initially used. Furthermore, amelioration of metric output was observed when the original starting plasma amount of 100 uL was increased to 200 uL in Kit A. Nanodrop quantities ranged from 8.85 - 32.65 ng/uL and -72.82 - 4.98 ng/uL using Kit A and Kit B, respectively. The quality (260/280 ratios) ranged from -7.65 - 3.17 and -41.65 - 6.13 for Kit A and Kit B, respectively. Taqman amplification was achieved for both kits. Conclusions: Although total RNA isolation was effectively performed, there is a need for properly optimizing miRNA detection in these blood-based biopsies. Enhancing miRNA detection to determine treatment outcomes may result in miRNA’s becoming a powerful predictive biomarker. The goal is to utilize miRNAs as a diagnostic tool for real time monitoring of individualized therapy response, detecting developing metastases, and predicting relapse. Citation Format: Johnny I. Velasquez, Andrew Bass, Moein Rajaei, Curtic Bryant, Nancy Mendenhall, Luisel Ricks-Santi. Optimization of miRNA isolation from plasma biopsies of proton therapy prostate cancer patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 6707.
Even after radiation treatment, prostate cancer (PCa) patients receiving radiotherapy (RT) are still at risk for disease progression and recurrence. Predicting outcomes associated with cancer treatment is critical to PCa survivorship given that the 5-year survival rates for local and regional stage PCa is nearly 100%. Radiogenomics is a promising field of research focused on identifying genomic markers that can provide clinically useful prognostic predictions regarding radiation response and can potentially serve as the basis for personalized RT where cancer management is tailored to fit each individual patient. Circulating cell-free (ccfDNA) DNA has been found to 1) be associated with radiation sensitivity or toxicity, 2) relapse or recurrence, and 3) risk for the development of metastases before, during or following photon RT. Proton therapy, alternative to photon therapy, is a promising treatment that can reduce excess radiation dose and, in turn, the risk for adverse events. However, few studies have been done to determine if ccfDNA can predict response in proton radiation, which purports superior dose distribution, avoiding healthy tissues, minimizing the exit dose, and potentially reducing overall toxicity. The overall aim of this study is to determine if the quantity of ccfDNA is associated with PCa risk groups. We hypothesized that PCa patients within the highest risk group have quantitatively increased levels of ccfDNA compared to those in low and intermediate risk groups. This study leveraged the University of Florida Health Proton Therapy Institute Outcomes Tracking Protocol biobank of PCa patients with plasma and serum collected before, during and after proton RT. Isolation of ccfDNA at baseline, during treatment, and following treatment was undertaken and ccfDNA quantities were compared among patients in the low, intermediate and high risk groups using ANOVA. Our results indicate that the quantity difference between baseline and day 14 of treatment (p=0.055), 2 weeks post-treatment (p=0.54), and 4 weeks post-treatment (p=0.002) was associated with risk group. There was trend towards increasing ccfDNA quantity, as risk group increased; however, there was no correlation between risk group and treatment times using the Pearson correlation. Our results were consistent in that high ccfDNA quantity was associated with PCa risk. This is the first study determining the application of ccfDNA quantity on prostate cancer outcomes in patients undergoing proton RT. Identifying the determinants of radiation-related adverse outcomes will help inform impending predictive genomic technologies and improve cancer-related outcomes and survivorship. Citation Format: Andrew Bass, Johnny Velasquez, Moein Rajaei, Curtis Bryant, Nancy Mendenhall, Luisel J. Ricks-Santi. Association of circulating cell-free DNA and prostate cancer risk groups in patients undergoing proton therapy. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5594.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.