Comprehensive Two- and Three-Dimensional RNAi Screening Identifies PI3K Inhibition as a Complement to MEK Inhibitor AS703026 for Combination Treatment of Triple-Negative Breast Cancer

Triple-negative breast cancer (TNBC) is an aggressive subtype of breast cancer lacking targeted therapy. Here, we evaluated the anti-cancer activity of APR-246, a P53 activator, and CX-5461, a RNA polymerase I inhibitor, in the treatment of TNBC cells. We tested the efficacy of individual and combination therapy of CX-5461 and APR-246 in vitro, using a panel of breast cancer cell lines. Using publicly available breast cancer datasets, we found that components of RNA Pol I are predominately upregulated in basal-like breast cancer, compared to other subtypes, and this upregulation is associated with poor overall and relapse-free survival. Notably, we found that the treatment of breast cancer cells lines with CX-5461 significantly hampered cell proliferation and synergistically enhanced the efficacy of APR-246. The combination treatment significantly induced apoptosis that is associated with cleaved PARP and Caspase 3 along with Annexin V positivity. Likewise, we also found that combination treatment significantly induced DNA damage and replication stress in these cells. Our data provide a novel combination strategy by utilizing APR-246 in combination CX-5461 in killing TNBC cells that can be further developed into more effective therapy in TNBC therapeutic armamentarium.

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Pretreatment CLR 124 Positron Emission Tomography Accurately Predicts CLR 131 Three-Dimensional Dosimetry in a Triple-Negative Breast Cancer Patient

Cancer Biotherapy & Radiopharmaceuticals ◽

10.1089/cbr.2018.2568 ◽

2019 ◽

Vol 34 (1) ◽

pp. 13-23

Author(s):

Abigail E. Besemer ◽

Joseph J. Grudzinski ◽

Jamey P. Weichert ◽

Lance T. Hall ◽

Bryan P. Bednarz

Keyword(s):

Breast Cancer ◽

Positron Emission Tomography ◽

Cancer Patient ◽

Breast Cancer Patient ◽

Triple Negative Breast Cancer ◽

Triple Negative ◽

Three Dimensional ◽

Emission Tomography ◽

Positron Emission

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Wee1 Inhibition Enhances the Anti-Tumor Effects of Capecitabine in Preclinical Models of Triple-Negative Breast Cancer.

10.21203/rs.2.22903/v1 ◽

2020 ◽

Author(s):

Todd Pitts ◽

Dennis M Simmons ◽

Stacey M Bagby ◽

Sarah J Hartman ◽

Betelehem W Yacob ◽

...

Keyword(s):

Breast Cancer ◽

Cell Lines ◽

Triple Negative Breast Cancer ◽

Combination Treatment ◽

Triple Negative ◽

Single Agent ◽

Cell Analysis ◽

Preclinical Models ◽

Pdx Models ◽

Live Cell Analysis

Abstract Background: Triple-negative breast cancer (TNBC) is an aggressive subtype defined by lack of hormone receptor expression and non-amplified HER2. Adavosertib (AZD1775) is a potent, small molecule, ATP-competitive inhibitor of the Wee1 kinase that potentiates the activity of many DNA-damaging chemotherapeutics and is currently in clinical development for multiple indications. The purpose of this study was to investigate the combination of AZD1775 and capecitabine/5-FU in preclinical TNBC models. Methods: TNBC cell lines were treated with AZD1775 and 5-FU and cellular proliferation was assessed in real-time using IncuCyte® Live Cell Analysis. Apoptosis was assessed via the Caspase-Glo 3/7 assay system. Western blotting was used to assess changes in expression of downstream effectors. TNBC PDX models were treated with AZD1775, capecitabine, or the combination and assessed for tumor growth inhibition. Results: From the initial PDX screen, two of the four TNBC PDX models demonstrated a better response in the combination treatment than either of the single agents. As confirmation, two PDX models were expanded for statistical comparison . Both PDX models demonstrated a significant growth inhibition in the combination versus either of the single agents. (TNBC012, p<0.05 combo vs adavosertib or capecitabine, TNBC013, p<0.01 combo vs adavosertib or capecitabine ). An enhanced antiproliferative effect was observed in the adavosertib/5-FU combination treatment as measured by live cell analysis. An increase in apoptosis was observed in two of the four cell lines in the combination when compared to single agent treatment. Treatment with single agent adavosertib resulted in an increase in p-CDC2 in a dose dependent manner that was also observed in the combination treatment. Similar results were observed with γH2AX in two of the four cell lines tested. No significant changes were observed in Bcl-xL following treatment in any of the cell lines. Conclusions: The combination of adavosertib and capecitabine/5-FU demonstrated enhanced combination effects both in vitro and in vivo in preclinical models of TNBC. These results support the clinical investigation of this combination in patients with TNBC, including those with brain metastasis given the CNS penetration of both agents.

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The Interaction of PI3K Inhibition with Homologous Recombination Repair in Triple Negative Breast Cancer Cells

Journal of Pharmacy & Pharmaceutical Sciences ◽

10.18433/jpps30684 ◽

2019 ◽

Vol 22 ◽

pp. 599-611

Author(s):

Gamze Guney Eskiler

Keyword(s):

Breast Cancer ◽

Homologous Recombination ◽

Triple Negative Breast Cancer ◽

Triple Negative ◽

Apoptotic Cell ◽

Human Cancer ◽

Brca1 Mutation ◽

Annexin V ◽

Pi3k Inhibition ◽

Recombination Repair

Purpose: Aberrant activation of the phosphatidylinositol 3'-kinase (PI3K)-Akt signaling pathway is observed in many types of human cancer including triple negative breast cancer (TNBC). Additionally, dysregulation in the homologous recombination (HR)-dependent DNA-repair is associated with TNBC phenotype due to BRCA1/2 mutations or HR deficiency. Therefore, the hypothesis of this study was to evaluate the association of PI3K inhibition with HR pathway in TNBC in terms of BRCA1 mutation status. Methods: To examine the potential therapeutic effect of LY294002, an inhibitor of PI3K, on TNBC cell lines with known BRCA1 status, WST-1, annexin V, cell cycle analysis and AO/EB staining were performed. Additionally, RT-PCR and immunofluorescence analysis was used to explore the interaction between the inhibition of PI3K and HR functionality. Results: The findings showed that LY294002 could significantly inhibited the proliferation of TNBC cells. Furthermore, the suppression of PI3K resulted in HR impairment by BRCA1 and RAD51 downregulation and apoptotic cell death by the induction of DNA damage and BAX overexpression. Therefore, LY294002 was more effective in BRCA1-deficient TNBC cells. Conclusions: Consequently, targeted therapies based on the interaction of PI3K inhibition with BRCA1 mutations or HR deficiency in TNBC may be a promising strategy for the treatment of patients with TNBC.

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