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Fu X, Pereira R, Liu CC, De Angelis C, Shea MJ, Nanda S, Qin L, Mitchell T, Cataldo ML, Veeraraghavan J, Sethunath V, Giuliano M, Gutierrez C, Győrffy B, Trivedi MV, Cohen O, Wagle N, Nardone A, Jeselsohn R, Rimawi MF, Osborne CK, Schiff R. High FOXA1 levels induce ER transcriptional reprogramming, a pro-metastatic secretome, and metastasis in endocrine-resistant breast cancer. Cell Rep 2023; 42:112821. [PMID: 37467106 DOI: 10.1016/j.celrep.2023.112821] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Revised: 11/03/2022] [Accepted: 07/03/2023] [Indexed: 07/21/2023] Open
Abstract
Aberrant activation of the forkhead protein FOXA1 is observed in advanced hormone-related cancers. However, the key mediators of high FOXA1 signaling remain elusive. We demonstrate that ectopic high FOXA1 (H-FOXA1) expression promotes estrogen receptor-positive (ER+) breast cancer (BC) metastasis in a xenograft mouse model. Mechanistically, H-FOXA1 reprograms ER-chromatin binding to elicit a core gene signature (CGS) enriched in ER+ endocrine-resistant (EndoR) cells. We identify Secretome14, a CGS subset encoding ER-dependent cancer secretory proteins, as a strong predictor for poor outcomes of ER+ BC. It is elevated in ER+ metastases vs. primary tumors, irrespective of ESR1 mutations. Genomic ER binding near Secretome14 genes is also increased in mutant ER-expressing or mitogen-treated ER+ BC cells and in ER+ metastatic vs. primary tumors, suggesting a convergent pathway including high growth factor receptor signaling in activating pro-metastatic secretome genes. Our findings uncover H-FOXA1-induced ER reprogramming that drives EndoR and metastasis partly via an H-FOXA1/ER-dependent secretome.
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De Angelis C, Nardone A, Cataldo ML, Veeraraghavan J, Fu X, Giuliano M, Malorni L, Jeselsohn R, Osborne KC, Schiff R. Abstract P4-03-05: AP-1 as a potential mediator of resistance to the cyclin-dependent kinase (CDK) 4/6-inhibitor palbociclib in ER-positive endocrine-resistant breast cancer. Cancer Res 2018. [DOI: 10.1158/1538-7445.sabcs17-p4-03-05] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Background: The CDK4/6-inhibitor palbociclib (Palbo) in combination with endocrine therapy (ET) substantially improves progression-free survival compared to ET alone. However, almost all initial responders eventually develop resistance and relapse. Delineating the early adaptive signaling and the mechanisms underlying resistance to CDK4/6 inhibition is therefore crucial to identify new biomarkers and therapeutic targets to enhance the efficacy of Palbo and improve patient outcome.
Materials and Methods: MCF7 parental (P) cells and derivative lines made resistant (R) to tamoxifen (TamR), estrogen deprivation (EDR), or fulvestrant (FulR) were used. The MCF7P line and its endocrine-R (EndoR) derivatives were exposed to increasing concentrations of Palbo to generate acquired Palbo-R (PDR) models. The proteomic/signaling profiles of P and EndoR cells upon short-term Palbo treatment and as PDR develops were determined using reverse-phase protein arrays (RPPA). Transcriptional activity of the activator protein-1 (AP-1) transcription factor (TF) was measured by luciferase reporter assay. Global AP-1 blockade was achieved using a pINDUCER system to express doxycycline (Dox)-inducible dominant-negative (DN) c-Jun that lacks the transcriptional activation domain. Cell growth and colony formation were assessed using methylene blue staining and clonogenic assays, respectively. Levels of phosphorylated (p)-RB and CDK2 were assessed by Western Blot.
Results: In P and all EndoR cell models, Palbo inhibited cell growth and colony formation in a dose-dependent manner, though the inhibitory effect was greater in the EndoR cells compared to P cells [IC50 value of P cells >3 times that of EndoR lines (p<0.001); clonogenic % inhibition at 100nM = 54 in P and >85 in EndoR lines (p<0.001)]. Across the P and all EndoR models, short-term Palbo treatment resulted in increased levels of several membrane and intracellular signaling molecules, TFs, and enzymes. Among these, the AP-1 TF components c-Jun and p-c-Jun showed the highest increase across all models, with the utmost change observed in the TamR model (Fold-change = 4.4, 4.0 for total and p-c-Jun, respectively). Since we also observed that acquired resistance to Palbo in the TamR model was associated with higher AP-1 transcriptional activity and increased total and p-c-Fos levels, we assessed the efficacy of combining Palbo with AP-1 blockade in the TamR model. In two independent TamR clones ectopically expressing inducible DN-c-Jun, AP-1 blockade (+Dox) in combination with Palbo was highly effective in inhibiting cell growth and reducing p-RB and CDK2 levels compared to single agent treatments. In addition, in both the TamR/DN-c-Jun-expressing clones, the combination of Palbo, AP-1 blockade, and fulvestrant resulted in cell death and a significantly greater cell growth inhibition compared to any dual or mono treatments.
Conclusion: Our results suggest activation of AP-1 as a potential mechanism of resistance to Palbo in ER+ EndoR models. Transcriptomic profiling of the Palbo-sensitive and R cells, currently underway, will provide an in-depth understanding of the role of AP-1 as well as other key targets and associated molecular mechanisms in Palbo resistance.
Citation Format: De Angelis C, Nardone A, Cataldo ML, Veeraraghavan J, Fu X, Giuliano M, Malorni L, Jeselsohn R, Osborne KC, Schiff R. AP-1 as a potential mediator of resistance to the cyclin-dependent kinase (CDK) 4/6-inhibitor palbociclib in ER-positive endocrine-resistant breast cancer [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P4-03-05.
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Nardone A, Weir H, De Angelis C, Cataldo ML, Fu X, Shea MJ, Mitchell T, Trivedi M, Chamness GC, Osborne CK, Schiff R. Abstract P3-04-07: The new oral SERD AZD9496 is efficacious in antagonizing ER and circumventing resistance to endocrine therapy. Cancer Res 2017. [DOI: 10.1158/1538-7445.sabcs16-p3-04-07] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Background: The selective estrogen receptor (ER) degrader (SERD) fulvestrant (Ful) is a potent ER antagonist that upon binding to ER induces its degradation. Ful has shown clinical efficacy in metastatic disease upon progression on previous endocrine therapies and superior activitycompared to an aromatase inhibitor as first line therapy when given at a high dose, 500mg. However, major clinical limitations of Ful are its low bioavailability and its route of administration. Here, we assess the efficacy and the mechanism of action of the new oral SERD AZD9496 compared to Ful in our panel of endocrine-sensitive and -resistant (EndoR) in vitro and in vivo models.
Methods: The effects of AZD9496 and Ful were studied in vitro in various ER+ MCF7, ZR75-1, T47D, 600MPE, and MDAMB415 parental lines and in MCF7 and T47D derivatives made resistant (R) to estrogen deprivation (ED), tamoxifen (Tam), or Ful. Cell growth, Western blot, Q-RT-PCR, and ERE-reporter assays were conducted to assess treatment efficacy as well as ER levels and activity. Xenografts of parental MCF7 cells were established in ovariectomized nude mice with exogenous estrogen (E2). Mice were then randomized to continued E2 or ED, with and without AZD9496 or Ful. Mice bearing transplantable MCF7 EDR and TamR xenografts were randomized to continue original treatment or to switch to Ful or AZD9496, and tumor size was followed. Expression of classic and nonclassic/indirect ER-regulated genes was evaluated in RNA extracts of short-term-treated xenografts using the BioMark FLUIDIGM platform.
Results: AZD9496 inhibited cell growth (50-100%) of all ER+ parental cells and greatly, though not fully, degraded ER protein levels. AZD9496 also potently reduced ER-dependent exogenous and endogenous gene/protein expression in presence and absence of E2. In parental MCF7 xenograft-bearing mice, 10 days of AZD9496 resulted in a greater inhibition of tumor growth and in a greater reduction of levels of ER-dependent targets in comparison to Ful in the presence of E2. The effects of the 2 SERDs were similar in the absence of E2. In EndoR models that retain ER, AZD9496 inhibited cell growth in vitro by degrading ER, similar to Ful. Both SERDs also delayed tumor growth of EDR and TamR xenografts and effectively reduced levels of ER and ER-induced proteins, though no tumor regression was observed in the TamR model. Notably, AZD9496 failed to inhibit growth of FulR cells and xenografts. Expression analysis showed that the 2 SERDs potently inhibited classic ER activity, while simultaneously increasing expression of some genes known to be regulated by the nonclassic/indirect ER activity, including genes involved in escape pathways of endocrine resistance.
Conclusions: The oral SERD AZD9496 is a potent antiestrogen that antagonizes and degrades ER. AZD9496, like Ful, inhibits ER-dependent transcription and tumor growth in both naïve and resistant EDR and TamR models, but shows cross-resistance in FulR models. Both AZD9496 and Ful failed to completely reduce ER protein expression and to induce TamR tumor regression, suggesting that additional strategies to reduce ER levels and to enhance the inhibition of ER signaling and/or of co-operating survival mechanisms may be needed to improve treatment outcome.
Citation Format: Nardone A, Weir H, De Angelis C, Cataldo ML, Fu X, Shea MJ, Mitchell T, Trivedi M, Chamness GC, Osborne CK, Schiff R. The new oral SERD AZD9496 is efficacious in antagonizing ER and circumventing resistance to endocrine therapy [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P3-04-07.
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