Country：United States

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Oxford University Press (OUP)  

ABSTRACT

Competitive transplantation of cells expressing distinct fluorescent proteins is an attractive method for assessing cell competition and tumor clonality, albeit its use has been limited to mouse models. Rat mammary cancer is an alternative model to mice due to its similarity to human breast cancer. This study aims to implement competitive transplantation in the context of radiation biology of the rat mammary gland and to provide a detailed protocol on key techniques. Dissociated mammary cells were obtained from wild-type and transgenic rats expressing either green (EGFP) or red (Discosoma sp. red fluorescent protein [DsRed]) fluorescent protein. The cells were exposed to γ rays or left untreated, mixed at a specific ratio and then transplanted into the cleared fat pads of wild-type or double transgenic rats. We evaluated the expression of fluorescent proteins in epithelial outgrowths using confocal imaging of cleared tissues or on histological sections. Transplanting transgenic cells into wild-type recipients induced inflammation and rejection of the donor cells. Conversely, transplanting into double transgenics resulted in successful repopulation and observation of the fluorescent markers. A competitive assay between irradiated EGFP-expressing cells and unirradiated DsRed-expressing cells revealed that radiation exposure (4 Gy) did not affect repopulating ability, despite the theoretical sensitivity of the assay, suggesting the absence of strong competition between these cells. Analysis of tumors revealed the polyclonal nature of adenomas that developed in recipients exposed to radiation or 1-methyl-1-nitrosourea. Thus, this study developed a method to track cells in the rat mammary gland that is useful in radiation biology.

DOI： 10.1093/jrr/rrag007

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (other academic)   Publisher：openRxiv  

Abstract

Androgen receptor (AR) is a critical therapeutic target in prostate cancer (PCa), and androgen blockade is known to act synergistically with radiation therapy. However, the mechanisms through which AR modulates radiation response are not yet fully understood. In this study, we aimed to investigate the role of AR in mediating radioresistance in PCa. AR-positive LNCaP and castration-resistant C4-2 cells exhibited significantly higher radioresistance than AR-negative cells, as determined by apoptosis and cell viability assays. Following irradiation, most LNCaP cells were arrested in the G1 phase, accompanied by rapid p53 activation and p21 induction. Consistently, AR silencing significantly increased radiosensitivity and reduced DNA-PKcs expression and phosphorylation, suggesting that AR enhances DNA repair, likely through non-homologous end joining (NHEJ). At the cellular level, irradiation markedly induced macroautophagy in LNCaP and C4-2 cells, as evidenced by increased LC3B-II accumulation and autophagic vacuole formation, and the upregulation of 11 autophagy-related genes was identified by whole-transcriptomic analysis. To assess their functional relevance, we performed siRNA-mediated knockdown of selected autophagy-related genes and assessed cell viability and Annexin V/PI staining. Notably, BECN1 and LC3 knockdown significantly enhanced radiosensitivity, with BECN1 knockdown showing an effect comparable to that observed with AR silencing. These results suggest that radiation-induced autophagy promotes the survival of AR-positive prostate cancer cells. Moreover, immunohistochemical analysis of ex vivo- irradiated, patient - derived PCa tissues from patients with newly diagnosed high - Gleason score prostate cancer undergoing prostatectomy further demonstrated that radiation-induced autophagy supports the survival of high-grade AR-positive tumor cells. Collectively, our findings reveal that AR promotes radioresistance in PCa by enhancing both DNA repair and autophagy.

DOI： 10.64898/2025.12.03.690226

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Authorship：Last author   Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

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Event date： 2025.8

Language：English   Presentation type：Oral presentation (general)  

Venue：San Diego | The Alexandria   Country：United States  

Prostate cancer (PCa) is the second leading cause of cancer-related death in men worldwide. The first-line treatment for PCa involves androgen-deprivation therapy, which blocks androgen receptor (AR) activation. However, a more aggressive form termed castration-resistant prostate cancer (CRPC) may develop radioresistance through AR activation independent of androgen, contributing to tumor progression and propensity for distant metastasis. Based on previous studies, we hypothesize that autophagy promotes radioresistance in CRPC cells, and that inhibiting autophagy through knockdown of autophagy-related (ATG) genes may increase radiosensitivity. We will conduct siRNA-knockdown experiments targeting ATG genes ATG2A, MAP1LC3, and BECN1 in AR-positive PCa cell lines LNCaP and C4-2B to evaluate the role of autophagy in radioresistance. We expect low cell viability and increased levels of apoptotic markers in ATG siRNA-treated groups compared to scramble siRNA-treated groups post-irradiation, indicating increased radiosensitivity. Studying the relationship between autophagy and radioresistance may lead to development of novel therapeutics targeting CRPC.

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Other Link： https://www.biocom.org/people/adelynne-yang/

Event date： 2025.4

Language：English   Presentation type：Poster presentation  

Venue：Chicago, Illinois   Country：United States  

File： AACR e-poster v4 (Kenichi Kudo, COH).pdf

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Event date： 2023.10

Language：English   Presentation type：Poster presentation  

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Event date： 2022.2

Language：English   Presentation type：Poster presentation  

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Type：Academic research 

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