Abstract P1-08-01: Estrogen-induced cell cycle arrest and apoptosis in aromatase inhibitor-resistant breast cancer: Insights from single cells analysis of a patient-derived xenograft model

Abstract Background: Estrogen is known to promotes hormone-dependent breast cancer through activation of estrogen receptor (ER)-α encoded by ESR1. However, several clinical trials reported the unexpected therapeutic benefit of E2 for aromatase inhibitor (AI)-resistant cases of ER+ breast cancer. Considering potential impact of such clinical observation, we decided to determine the mechanisms of estrogen-induced tumor regression. Methods: A unique estrogen-inhibitory patient-derived xenograft (PDX) tumor, GS3, was established from an AI resistant ER+/HER2– brain metastatic breast cancer. In vivo estrogen suppression was confirmed through experiments by implanting 17β-estradiol (E2) pellets in mice carrying GS3, and then the single-cell analysis was performed using GS3 tumors. In vitro E2 suppression analysis was carried out using organoids from GS3.Results: The E2-induced suppression of GS3 involves ERα, which was wild-type and not amplified. Single cell RNA sequencing analysis of this PDX has revealed that E2 treatment (for 1 week) induces cell cycle arrest in both ESR1+ cells and ESR1– cells, demonstrating the unexpected influence of estrogen on ESR1– cells in ER+ breast cancer. E2 upregulated the expression of estrogen-regulated genes, including a tumor suppressor gene, IL24, and lower levels of IL24 were linked to estrogen independence, after three rounds of intermittent E2 treatment. IL24+ cells included more G1 phase cells of cell cycle compared to IL24– cells. Hallmark apoptosis gene sets were upregulated and the hallmark G2M checkpoint gene set was downregulated in IL24+ cells after E2 treatment. The number of apoptotic cells was significantly increased after long term (for 4 weeks) E2 treatment. Western blotting analysis demonstrated that long term E2 treatment induced expression of apoptosis-associated protein cleaved-PARP and reduction of the pro-survival protein Bcl-xl level.Conclusions: There is the need of markers for patients who can benefit from E2 treatment after AI resistance, and measurements of ER and PR expression are not enough. Analysis of GS3 PDX has revealed that estrogen induces cell cycle arrest and apoptosis. Our study has revealed the cross-talk between ESR1+ and ESR1– cells as well as potential roles of IL24 in estrogen-suppressive tumors.

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Abstract PD7-02: Estrogen-induced cell cycle arrest as an unexpected outcome of aromatase inhibitor-resistance: Insights from single-cell trajectory analysis of a patient-derived xenograft model

10.1158/1538-7445.sabcs20-pd7-02 ◽

2021 ◽

Author(s):

Hitomi Mori ◽

Kohei Saeki ◽

Gregory Chang ◽

Xiwei Wu ◽

Pei-Yin Hsu ◽

...

Keyword(s):

Cell Cycle ◽

Aromatase Inhibitor ◽

Trajectory Analysis ◽

Xenograft Model ◽

Cycle Arrest ◽

Patient Derived Xenograft ◽

Aromatase Inhibitor Resistance ◽

Cell Trajectory ◽

Unexpected Outcome ◽

Inhibitor Resistance

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Influence of Estrogen Treatment On ESR1+ and ESR1- Cells In ER+ Breast Cancer: Insights From Single-Cell Analysis of Patient-Derived Xenograft Models

10.21203/rs.3.rs-816591/v1 ◽

2021 ◽

Author(s):

Hitomi Mori ◽

Kohei Saeki ◽

Gregory Chang ◽

Jinhui Wang ◽

Xiwei Wu ◽

...

Keyword(s):

Breast Cancer ◽

Cell Cycle ◽

Single Cell ◽

Cell Cycle Arrest ◽

Single Cell Analysis ◽

Estrogen Treatment ◽

Cell Analysis ◽

Cycle Arrest ◽

Patient Derived Xenograft

Abstract Background: Estrogen typically promotes the progression of hormone-dependent breast cancer through activation of estrogen receptor (ER)-α encoded by ESR1. While estrogen-induced tumor suppression in ER+ breast cancer has been clinically observed as an unexpected outcome of aromatase inhibitor (AI)-resistance, the molecular mechanisms have not yet been fully defined. Characterization of estrogen regulation in two ER+ breast cancer patient-derived xenograft (PDX) models with opposite responses to estrogen offered us an unprecedented opportunity to assess how 17β-estradiol (E2) modulates ER+ cancer.Methods: We established two PDX breast cancer models in mice using ER+ tumors from patients that responded (SC31) or were suppressed (GS3) by exogenous estrogen. In vivo tumor promotion or suppression by estrogen were confirmed through experiments by implanting E2 pellets in mice carrying SC31 or GS3, and then single-cell analysis was performed.Results: E2 promoted SC31 tumor growth but suppressed growth of GS3 in vivo. The E2-mediated suppression of GS3 involves ERα, which was wild-type and not amplified. Single-cell RNA sequencing analysis showed that E2 treatment induced cell cycle promotion in SC31, while E2 induced cell cycle arrest in GS3. However, E2 treatment upregulated the expression of estrogen-regulated genes in both tumors. These gene-expression changes by E2 occurred in both ESR1+ cells and ESR1– cells within the same tumor, demonstrating for the first time the influence of estrogen on ESR1– cells in ER+ breast tumors. E2 also upregulated a tumor suppressor gene, IL24, only in GS3, and lower levels of IL24 were linked to estrogen independence, after three rounds of intermittent E2 treatment. More IL24+ cells were ESR1+ and in G1 phase than IL24– cells. Hallmark apoptosis gene sets were upregulated and the hallmark G2M checkpoint gene set was downregulated in IL24+ cells after E2 treatment.Conclusions: Our study has revealed the effects of estrogen treatment on both ESR1+ and ESR1– cells in ER+ tumors, but not all ER+ cancers respond the same manner to estrogen. SC31 is a tumor that is stimulated by E2, while GS3 is suppressed by E2 via cell cycle arrest. Our results indicate a potential role of IL24 in estrogen-suppressive tumors.

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Exploring a Link Between NF-kappaB and G2/M Cell Cycle Arrest in Breast Cancer Cells

10.21236/ada425730 ◽

2004 ◽

Author(s):

Shelly M. Davis

Keyword(s):

Breast Cancer ◽

Cell Cycle ◽

Cell Cycle Arrest ◽

Cancer Cells ◽

Breast Cancer Cells ◽

M Cell ◽

Cycle Arrest ◽

Nf Kappab

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Exploring a Link Between NF-KB and G2/M Cell Cycle Arrest in Breast Cancer Cells

10.21236/ada436875 ◽

2005 ◽

Author(s):

Shelly M. Davis ◽

Shigeki Miyamoto

Keyword(s):

Breast Cancer ◽

Cell Cycle ◽

Cell Cycle Arrest ◽

Cancer Cells ◽

Breast Cancer Cells ◽

M Cell ◽

Cycle Arrest

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Molecular Mechanisms of Thymoquinone as Anticancer agent

Combinatorial Chemistry & High Throughput Screening ◽

10.2174/1386207323999201027225305 ◽

2020 ◽

Vol 23 ◽

Author(s):

Fatma Ismail Alhmied ◽

Ali Hassan Alammar ◽

Bayan Mohammed Alsultan ◽

Marooj Alshehri ◽

Faheem Hyder Pottoo

Keyword(s):

Breast Cancer ◽

Cell Cycle ◽

Cell Cycle Arrest ◽

Human Breast Cancer ◽

Phase Cell ◽

Cycle Phase ◽

Human Breast ◽

Cycle Arrest ◽

Phase Arrest ◽

Anti Cancer

Abstract:: Thymoquinone (TQ), the bioactive constituent of Nigella Sativa seeds is a well-known natural compound for the management of several types of cancers. The anti-cancer properties of thymoquinone are thought to be operated via intervening with various oncogenic pathways including cell cycle arrest, prevention of inflammation and oxidative stress, induction of invasion, metastasis, inhibition of angiogenesis, and apoptosis. As well as up-regulation and down-regulation of specific tumor suppressor genes and tumor promoting genes, respectively. Proliferation of various tumor cells is inhibited by TQ via induction of cell cycle arrest, disruption of the microtubule organization, and down regulating cell survival protein expression. TQ induces G1 phase cell cycle arrest in human breast cancer, colon cancer and osteosarcoma cells through inhibiting the activation of cyclin E or cyclin D and up-regulating p27and p21 a cyclin dependent kinase (Cdk) inhibitor. TQ concentration is a significant factor in targeting a particular cell cycle phase. While high concentration of TQ induced G2 phase arrest in human breast cancer (MCF-7) cells, low concentration causes S phase arrest. This review article provides mechanistic insights into the anti-cancer properties of thymoquinone.

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Mutant p53L194F Harboring Luminal-A Breast Cancer Cells Are Refractory to Apoptosis and Cell Cycle Arrest in Response to MortaparibPlus, a Multimodal Small Molecule Inhibitor

Cancers ◽

10.3390/cancers13123043 ◽

2021 ◽

Vol 13 (12) ◽

pp. 3043

Author(s):

Ahmed Elwakeel ◽

Anissa Nofita Sari ◽

Jaspreet Kaur Dhanjal ◽

Hazna Noor Meidinna ◽

Durai Sundar ◽

...

Keyword(s):

Breast Cancer ◽

Cell Cycle ◽

Cell Cycle Arrest ◽

Cancer Cells ◽

Small Molecule ◽

Breast Cancer Cells ◽

Luminal A ◽

Molecular Analyses ◽

Cycle Arrest ◽

Mcf 7

We previously performed a drug screening to identify a potential inhibitor of mortalin–p53 interaction. In four rounds of screenings based on the shift in mortalin immunostaining pattern from perinuclear to pan-cytoplasmic and nuclear enrichment of p53, we had identified MortaparibPlus (4-[(1E)-2-(2-phenylindol-3-yl)-1-azavinyl]-1,2,4-triazole) as a novel synthetic small molecule. In order to validate its activity and mechanism of action, we recruited Luminal-A breast cancer cells, MCF-7 (p53wild type) and T47D (p53L194F) and performed extensive biochemical and immunocytochemical analyses. Molecular analyses revealed that MortaparibPlus is capable of abrogating mortalin–p53 interaction in both MCF-7 and T47D cells. Intriguingly, upregulation of transcriptional activation function of p53 (as marked by upregulation of the p53 effector gene—p21WAF1—responsible for cell cycle arrest and apoptosis) was recorded only in MortaparibPlus-treated MCF-7 cells. On the other hand, MortaparibPlus-treated T47D cells exhibited hyperactivation of PARP1 (accumulation of PAR polymer and decrease in ATP levels) as a possible non-p53 tumor suppression program. However, these cells did not show full signs of either apoptosis or PAR-Thanatos. Molecular analyses attributed such a response to the inability of MortaparibPlus to disrupt the AIF–mortalin complexes; hence, AIF did not translocate to the nucleus to induce chromatinolysis and DNA degradation. These data suggested that the cancer cells possessing enriched levels of such complexes may not respond to MortaparibPlus. Taken together, we report the multimodal anticancer potential of MortaparibPlus that warrants further attention in laboratory and clinical studies.

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