Functional Impacts of the BRCA1-mTORC2 Interaction in Breast Cancer

Deleterious mutations in Breast Cancer 1 (BRCA1) are associated with an increased risk of breast and ovarian cancer. Mutations in the tandem BRCA1 C-terminal (tBRCT) protein domain disrupt critical protein interactions required for the faithful repair of DNA through homologous recombination, which contributes to oncogenesis. Our studies have identified RICTOR, PRR5, and SIN1 subunits of the mammalian target of rapamycin complex 2 (mTORC2) as interacting partners with the tBRCT domain of BRCA1 leading to the disruption of the mTORC2 complex. However, the interplay between mTORC2 signaling and BRCA1 function in the DNA damage response (DDR) remains to be determined. In this study, we used protein interaction assays to determine the binary interactions between the tBRCT domain and mTORC2 subunits, evaluated the impact of mTOR inhibition on the transcriptional function of the tBRCT, evaluated the impact of mTOR signaling on BRCA1 recruitment to DNA damage-induced foci and determined the breast cancer cell line response to mTOR inhibition dependent upon BRCA1 expression and mutation. This study determined that PRR5, RICTOR, and SIN1 could each independently interact with the BRCA1 tBRCT. Inhibition of mTORC1, but not mTORC1/2, increases BRCA1 transcriptional activation activity. Treatment with pan-mTOR inhibitor PP242 diminishes DNA damage-induced γH2AX and BRCA1 foci formation. Breast cancer cells lacking expression of functional BRCA1 are more sensitive to mTOR inhibitors. These data suggest that mTOR signaling is required for BRCA1 response to DNA damage and breast cancer cells lacking BRCA1 are more sensitive to pan-mTOR inhibition. This work suggests chemotherapeutic strategies using mTOR inhibitors could be tailored for patients that lack functional BRCA1.

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Effect of mTOR inhibition on sensitivity of triple-negative breast cancer cells to epidermal growth factor inhibition

Journal of Clinical Oncology ◽

10.1200/jco.2009.27.15_suppl.1055 ◽

2009 ◽

Vol 27 (15_suppl) ◽

pp. 1055-1055 ◽

Cited By ~ 1

Author(s):

T. Liu ◽

R. Yacoub ◽

T. Graham ◽

L. Yang ◽

M. Tighiouart ◽

...

Keyword(s):

Breast Cancer ◽

Metastatic Breast Cancer ◽

Cancer Cells ◽

Breast Cancer Cells ◽

Triple Negative ◽

Metastatic Breast ◽

Mtor Inhibitors ◽

Egfr Inhibitors ◽

Breast Cancers ◽

Mtor Inhibition

1055 Background: The outcome for patients with triple negative (TN) cancers is poor at least in part because of a lack of targeted therapies. Although 50% of TN breast cancers over-express EGFR, the use of EGFR inhibitors as single agents in patients with unselected and TN metastatic breast cancers has produced disappointing results. Likewise, mTOR inhibitors have modest activity as single agents in metastatic breast cancer. mTOR inhibitors have been demonstrated to activate the Akt pathway by a possible feedback mechanism, which could potentially sensitize TN breast cancer cells to upstream inhibitors. We have previously demonstrated that EGFR inhibitors in combination with rapamycin (RAPA) decrease cell survival, increase apoptosis, and are synergistic in TN breast cancer cells, compared to any of the agents alone (AACR 2008). We, therefore, evaluated the combination of mTOR and EGFR inhibition in vivo. Methods: Athymic mice were inoculated with TN (MDA-MB-231) breast cancer cells. One week after cell inoculation, mice were treated with vehicle, lapatinib 75mg/kg by mouth daily, RAPA 3mg/kg IP biweekly, or the combination. After 4 weeks of treatment, mice were sacrificed and tumors were assessed for target proteins by Western blotting and immunohistochemistry Results: The combination of RAPA and lapatinib resulted in a significant decrease in TN breast tumor volume (76 mm3), compared to rapamycin alone (133 mm3, p = 0.01), lapatinib alone (183 mm3, p < 0.0001) or control (188 mm3, p = 0.005). Neither lapatinib nor RAPA alone inhibited tumor growth significantly compared to control (p > 0.05). Interestingly, in contrast to our findings in vitro, the increase in pAkt noted in RAPA treated tumors was not decreased by lapatinib, despite the significant decrease in tumor size in tumors treated with the combination. Conclusions: These studies demonstrate that the combination of mTOR inhibition and lapatinib significantly inhibit TN breast cancer growth, compared with either agent alone. Given the lack of targeted therapies in TN breast cancers, these data support the possibility that mTOR inhibition can sensitize TN breast cancers to EGFR inhibitors. A clinical trial evaluating the combination of lapatinib and RAD001 as second-line therapy for TN metastatic breast cancer is planned. [Table: see text]

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The Impact of Antioxidants from the Diet on Breast Cancer Cells Monitored by Raman Microspectroscopy

Letters in Drug Design & Discovery ◽

10.2174/1570180815666180502120804 ◽

2018 ◽

Vol 16 (2) ◽

pp. 127-137

Author(s):

Paula Sofia Coutinho Medeiros ◽

Ana Lúcia Marques Batista de Carvalho ◽

Cristina Ruano ◽

Juan Carlos Otero ◽

Maria Paula Matos Marques

Keyword(s):

Breast Cancer ◽

Cancer Cells ◽

Cell Line ◽

Breast Cancer Cells ◽

Triple Negative ◽

Breast Adenocarcinoma ◽

Coumaric Acid ◽

Human Breast ◽

The Impact

Background: The impact of the ubiquitous dietary phenolic compound p-coumaric acid on human breast cancer cells was assessed, through a multidisciplinary approach: Combined biological assays for cytotoxicity evaluation and biochemical profiling by Raman microspectroscopic analysis in cells. </P><P> Methods: Para-coumaric acid was shown to exert in vitro chemoprotective and antitumor activities, depending on the concentration and cell line probed: a significant anti-invasive ability was detected for the triple-negative MDA-MB-231 cells, while a high pro-oxidant effect was found for the estrogen- dependent MCF-7 cells. A striking cell selectivity was obtained, with a more noticeable outcome on the triple-negative MDA-MB-231 cell line. Results: The main impact on the cellular biochemical profile was verified to be on proteins and lipids, thus justifying the compound´s anti-invasive effect and chemoprotective ability. Conclusion: p-Coumaric acid was thus shown to be a promising chemoprotective/chemotherapeutic agent, particularly against the low prognosis triple-negative human breast adenocarcinoma.

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Targeting of lactate dehydrogenase C dysregulates the cell cycle and sensitizes breast cancer cells to DNA damage response targeted therapy.

Molecular Oncology ◽

10.1002/1878-0261.13024 ◽

2021 ◽

Author(s):

Adviti Naik ◽

Julie Decock

Keyword(s):

Breast Cancer ◽

Cell Cycle ◽

Dna Damage ◽

Targeted Therapy ◽

Lactate Dehydrogenase ◽

Cancer Cells ◽

Dna Damage Response ◽

Breast Cancer Cells ◽

Damage Response ◽

Lactate Dehydrogenase C

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Chaga mushroom extract induces autophagy via the AMPK-mTOR signaling pathway in breast cancer cells

Journal of Ethnopharmacology ◽

10.1016/j.jep.2021.114081 ◽

2021 ◽

pp. 114081

Author(s):

Min-Gu Lee ◽

Yun-Suk Kwon ◽

Kyung-Soo Nam ◽

Seo Yeon Kim ◽

In Hyun Hwang ◽

...

Keyword(s):

Breast Cancer ◽

Cancer Cells ◽

Signaling Pathway ◽

Breast Cancer Cells ◽

Mtor Signaling ◽

Mtor Signaling Pathway ◽

Mushroom Extract

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Quantitative phosphoproteomics reveals genistein as a modulator of cell cycle and DNA damage response pathways in triple-negative breast cancer cells

International Journal of Oncology ◽

10.3892/ijo.2016.3327 ◽

2016 ◽

Vol 48 (3) ◽

pp. 1016-1028 ◽

Cited By ~ 25

Author(s):

YI FANG ◽

QIAN ZHANG ◽

XIN WANG ◽

XUE YANG ◽

XIANGYU WANG ◽

...

Keyword(s):

Breast Cancer ◽

Cell Cycle ◽

Dna Damage ◽

Cancer Cells ◽

Dna Damage Response ◽

Triple Negative Breast Cancer ◽

Breast Cancer Cells ◽

Triple Negative ◽

Damage Response ◽

Quantitative Phosphoproteomics

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A radiosensitizer, gallotannin-rich extract from Bouea macrophylla seeds, inhibits radiation-induced epithelial-mesenchymal transition in breast cancer cells

BMC Complementary Medicine and Therapies ◽

10.1186/s12906-021-03363-6 ◽

2021 ◽

Vol 21 (1) ◽

Author(s):

Jiraporn Kantapan ◽

Siwaphon Paksee ◽

Aphidet Duangya ◽

Padchanee Sangthong ◽

Sittiruk Roytrakul ◽

...

Keyword(s):

Breast Cancer ◽

Dna Damage ◽

Cell Death ◽

Cancer Cells ◽

Breast Cancer Cells ◽

Epithelial Mesenchymal Transition ◽

Breast Cancer Cell Lines ◽

Mesenchymal Transition ◽

Mammosphere Formation ◽

Radiation Induced

Abstract Background Radioresistance can pose a significant obstacle to the effective treatment of breast cancers. Epithelial–mesenchymal transition (EMT) is a critical step in the acquisition of stem cell traits and radioresistance. Here, we investigated whether Maprang seed extract (MPSE), a gallotannin-rich extract of seed from Bouea macrophylla Griffith, could inhibit the radiation-induced EMT process and enhance the radiosensitivity of breast cancer cells. Methods Breast cancer cells were pre-treated with MPSE before irradiation (IR), the radiosensitizing activity of MPSE was assessed using the colony formation assay. Radiation-induced EMT and stemness phenotype were identified using breast cancer stem cells (CSCs) marker (CD24−/low/CD44+) and mammosphere formation assay. Cell motility was determined via the wound healing assay and transwell migration. Radiation-induced cell death was assessed via the apoptosis assay and SA-β-galactosidase staining for cellular senescence. CSCs- and EMT-related genes were confirmed by real-time PCR (qPCR) and Western blotting. Results Pre-treated with MPSE before irradiation could reduce the clonogenic activity and enhance radiosensitivity of breast cancer cell lines with sensitization enhancement ratios (SERs) of 2.33 and 1.35 for MCF7 and MDA-MB231cells, respectively. Pretreatment of breast cancer cells followed by IR resulted in an increased level of DNA damage maker (γ-H2A histone family member) and enhanced radiation-induced cell death. Irradiation induced EMT process, which displayed a significant EMT phenotype with a down-regulated epithelial marker E-cadherin and up-regulated mesenchymal marker vimentin in comparison with untreated breast cancer cells. Notably, we observed that pretreatment with MPSE attenuated the radiation-induced EMT process and decrease some stemness-like properties characterized by mammosphere formation and the CSC marker. Furthermore, pretreatment with MPSE attenuated the radiation-induced activation of the pro-survival pathway by decrease the expression of phosphorylation of ERK and AKT and sensitized breast cancer cells to radiation. Conclusion MPSE enhanced the radiosensitivity of breast cancer cells by enhancing IR-induced DNA damage and cell death, and attenuating the IR-induced EMT process and stemness phenotype via targeting survival pathways PI3K/AKT and MAPK in irradiated breast cancer cells. Our findings describe a novel strategy for increasing the efficacy of radiotherapy for breast cancer patients using a safer and low-cost natural product, MPSE.

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