Flow Cytometry Definition of Rat Mammary Epithelial Cell Populations and Their Distinct Radiation Responses

Kudo, Ken-Ichi; Takabatake, Masaru; Nagata, Kazuhiro; Nishimura, Yukiko; Daino, Kazuhiro; Iizuka, Daisuke; Nishimura, Masaharu; Suzuki, Keiji; Kakinuma, Shizuko; Imaoka, Tatsuhiko

doi:10.1667/rr15566.1

Cited by 7 publications

(9 citation statements)

References 39 publications

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“…γH2AX foci are formed at 1 h, and mostly disappear by 4 h, after a single high-dose (2–6 Gy) irradiation in basal and luminal mammary cells of BALB/c mice, Sprague–Dawley rats and human tissue xenografts and the response is generally more prominent in luminal than basal cells [ 91–93 ], although these studies did not conclude whether this also holds true for TEBs and TDLU. γH2AX induction in luminal progenitor cells and mature cells is similar and dose dependent in rats [ 93 ]. Basal cells might have high non-homologous end joining (NHEJ) activity in BALB/c mice [ 92 ], although, controversially, they are prone to radiation-induced cell death as mentioned below.…”

Section: Studies Towards Understanding the Mechanisms Underlying Dose...mentioning

confidence: 99%

“…In BALB/c mice, most basal and luminal cells show reduced Ki67-positive fractions after acute 6 Gy irradiation, implying entrance to G0, while a subset of proliferative basal mammary cells exhibit G2 arrest [ 92 ]. In Sprague–Dawley rats, release from cell cycle arrest occurs in basal cells by 24 h, when luminal cells show longer arrest [ 93 ].…”

Section: Studies Towards Understanding the Mechanisms Underlying Dose...mentioning

confidence: 99%

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Molecular and cellular basis of the dose-rate-dependent adverse effects of radiation exposure in animal models. Part I: Mammary gland and digestive tract

Suzuki

Imaoka

Tomita

et al. 2023

Journal of Radiation Research

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While epidemiological data are available for the dose and dose-rate effectiveness factor (DDREF) for human populations, animal models have contributed significantly to providing quantitative data with mechanistic insights. The aim of the current review is to compile both the in vitro experiments with reference to the dose-rate effects of DNA damage and repair, and the animal studies, specific to rodents, with reference to the dose-rate effects of cancer development. In particular, the review focuses especially on the results pertaining to underlying biological mechanisms and discusses their possible involvement in the process of radiation-induced carcinogenesis. Because the concept of adverse outcome pathway (AOP) together with the key events has been considered as a clue to estimate radiation risks at low doses and low dose-rates, the review scrutinized the dose-rate dependency of the key events related to carcinogenesis, which enables us to unify the underlying critical mechanisms to establish a connection between animal experimental studies with human epidemiological studies.

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Section: Studies Towards Understanding the Mechanisms Underlying Dose...mentioning

confidence: 99%

Section: Studies Towards Understanding the Mechanisms Underlying Dose...mentioning

confidence: 99%

Molecular and cellular basis of the dose-rate-dependent adverse effects of radiation exposure in animal models. Part I: Mammary gland and digestive tract

Suzuki

Imaoka

Tomita

et al. 2023

Journal of Radiation Research

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“…It has been thought that mammary stem cells are present among the basal cells because regenerative mammary glands are produced when mammary basal cells isolated from primary mammary cells by cell sorting are transplanted into rodent mammary fat pads [ 17 , 18 ]. In addition, it has been recently reported that 3D culture of human and rat mammary basal cells in collagen gels yields mammary organoids that resemble in vivo structures [ 27 , 35 ]. Therefore, we developed mammary organoids with both ΔNp63α-expressing and non-ΔNp63α-expressing cells by culturing collagen-embedded HMECs and observed the expression of p21 by immunostaining after irradiation.…”

Section: Resultsmentioning

confidence: 99%

“…Human mammary organoids were generated as described previously [ 27 ]. HMECs were mixed on ice with HuMECs containing 2 mg/mL rat tail collagen I (Corning Inc., Corning, NY, USA).…”

Section: Methodsmentioning

confidence: 99%

“…However, few studies have focused on the transcriptional repressor activity of ΔNp63α in this field. Two studies have previously reported that mammary basal cells are less responsive to radiation than mammary luminal cells, differentiating cells from basal stem/progenitor cells [ 26 , 27 ]. If basal stem cells that have genetic mutations and chromosomal aberrations continue to divide and differentiate for a long time, cancerous cells may be expected to develop.…”

Section: Introductionmentioning

confidence: 99%

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ΔNp63α transcriptionally represses p53 target genes involved in the radiation-induced DNA damage response

et al. 2022

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Background The DNA damage response (DDR) is a mechanism that protects cells against radiation-induced oxidative DNA damage by causing cell cycle arrest and apoptosis. TP63 is a member of the tumour suppressor TP53 gene family, and ΔNp63α, a TP63 splicing variant, is constitutively expressed in the stem cell-containing basal layer of stratified epithelial tissues, including the mammary gland, where it plays a critical role in stemness and tissue development. ΔNp63α has been reported to transcriptionally inhibit the tumour suppression protein p53. This p53-repressive activity may cause genomic instability in epithelial stem cells exposed to radiation. In this study, we analysed the inhibitory effect of ΔNp63α on radiation-induced DDR. Methods To elucidate the role of the p53-repressive effect of ΔNp63α in radiation response, we performed a p63-siRNA knockdown experiment using human mammary epithelial cells (HMECs) expressing ΔNp63α and then performed ectopic and entopic expression experiments using human induced pluripotent stem cells (hiPSCs). After irradiation, the expression of DDR-related genes and proteins in ΔNp63α-expressing and control cells was analysed by RT–qPCR, Western blotting, and flow cytometry. Results The mRNA/protein expression levels of BAX and p21 were significantly increased in p63-siRNA-treated HMECs (sip63) after X-ray irradiation (4 Gy, 0.7 Gy/min) but not in scramble-siRNA treated HMECs (scr). Transcriptomic analysis showed decreased RNA expression of cell cycle-related genes and increased expression of programmed cell death-related genes in sip63 cells compared to scr cells. Furthermore, flow cytometric analysis revealed an increase in apoptotic cells and a decrease in 5-ethynyl-2´-deoxyuridine uptake in sip63 cells compared to scr cells. On the other hand, both the ectopic and entopic expression of ΔNp63α in apoptosis-sensitive hiPSCs reduced the expression levels of BAX after irradiation and significantly decreased the number of apoptotic cells induced by radiation. Conclusion Taken together, these results indicate that ΔNp63α represses p53-related radiation-induced DDR, thereby potentially causing genomic instability in epithelial stem cells.

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The effect of radiation on the ability of rat mammary cells to form mammospheres

Hosoki¹,

Ogawa

Nishimura

et al. 2020

Radiat Environ Biophys

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Flow Cytometry Definition of Rat Mammary Epithelial Cell Populations and Their Distinct Radiation Responses

Cited by 7 publications

References 39 publications

Molecular and cellular basis of the dose-rate-dependent adverse effects of radiation exposure in animal models. Part I: Mammary gland and digestive tract

Molecular and cellular basis of the dose-rate-dependent adverse effects of radiation exposure in animal models. Part I: Mammary gland and digestive tract

ΔNp63α transcriptionally represses p53 target genes involved in the radiation-induced DNA damage response

The effect of radiation on the ability of rat mammary cells to form mammospheres

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