Posters
Presenting Author Academic/Professional Position
Undergraduate
Academic Level (Author 1)
Undergraduate
Discipline/Specialty (Author 1)
Immunology and Microbiology
Academic Level (Author 2)
Post-doc
Discipline/Specialty (Author 2)
Immunology and Microbiology
Academic Level (Author 3)
Graduate Student
Discipline/Specialty (Author 3)
Immunology and Microbiology
Academic Level (Author 4)
Post-doc
Discipline/Specialty (Author 4)
Immunology and Microbiology
Academic Level (Author 5)
Undergraduate
Discipline/Specialty (Author 5)
Immunology and Microbiology
Presentation Type
Poster
Discipline Track
Biomedical Science
Abstract Type
Research/Clinical
Abstract
Background: The G protein–coupled estrogen receptor (GPER) mediates rapid estrogen signaling that promotes proliferation, migration, and therapeutic resistance in breast cancer, including in hormone receptor–negative subtypes. Notably, standard endocrine therapies may inadvertently activate GPER, highlighting the need for direct targeting of this pathway. The objectives of this study were to evaluate GPER as a therapeutic target using pharmacologic modulators and to determine how GPER-driven tumor behavior relates to tumor microbiome composition across breast cancer subtypes.
Methods: Breast cancer cell lines representing Luminal A (MCF7), Luminal B (BT474), HER2-enriched (SKBR3), and triple-negative (HCC38, MDA-MB-453, MDA-MB-231) subtypes were treated with Ormeloxifene (ORM). Effects on cell morphology and proliferation were assessed using MTT assays to determine dose-response relationships and IC₅₀ values. Cell migration and clonogenic survival were evaluated using wound healing and colony formation assays. GPER protein levels were assessed by Western blot. GPER signaling activity was evaluated using fluorescence-based intracellular calcium imaging following stimulation with the GPER agonist G1 and inhibition with ORM or the antagonist G36. For microbiome analysis, 16S rRNA sequencing was performed on breast cancer tissues to evaluate bacterial abundance, alpha and beta diversity, and subtype-specific taxonomic distributions. Additional analyses examined microbial biomarkers associated with metastatic status, age, and molecular subtype. The effects of CDK and PARP inhibitors are also evaluated in breast cancer models in the context of GPER-targeted therapy. Statistical analyses included multigroup comparisons and diversity metrics.
Results: Ormeloxifene induced marked, dose-dependent growth inhibition across all breast cancer subtypes tested, with an approximate IC₅₀ of 10 μM. ORM significantly reduced wound closure and colony formation and produced visible alterations in cell morphology. Western blot analysis demonstrated reduced GPER protein levels following ORM treatment. Functional assays showed that G1-induced calcium mobilization was effectively blocked by ORM pretreatment and by G36, confirming inhibition of GPER-mediated signaling. Microbiome profiling revealed distinct bacterial compositions among molecular subtypes, with significant differences in alpha and beta diversity, Firmicutes/Bacteroidetes ratios, and subtype-specific dominant taxa. Specific microbial species were identified as biomarkers associated with metastatic disease, younger age (< 50), and aggressive tumor subtypes. These datasets also provide a framework for interpreting responses to CDK and PARP inhibitors within GPER-defined tumor contexts.
Conclusions: GPER is a therapeutically actionable driver of breast cancer progression across multiple subtypes. Ormeloxifene effectively suppresses GPER expression and signaling, resulting in broad anti-tumor activity. Integration of tumor microbiome profiles with GPER signaling reveals additional layers of biological heterogeneity that may inform personalized therapeutic strategies. Evaluation of CDK and PARP inhibitors within this GPER-centered framework further expands the translational relevance of this targeting strategy.
Recommended Citation
Vidaurri, Sierra E.; Singh, Shweta; Ledezma, Valerie E.; Baru, Rajesekhar; Garza, Emma; Flores, Francisco; Noorani, Muhammad; Goyal, Shubhank; Calderon, Aura; Lim, Alexander; Dhasmana, Anupam; Dhasmana, Swati; Yallapu, Murali; Chauhan, Subhash; Nguyen, Diane; and Khan, Sheema, "GPER as a Therapeutic Target in Breast Cancer: Pharmacologic Inhibition and Microbiome Associations" (2026). Research Symposium. 5.
https://scholarworks.utrgv.edu/somrs/2026/posters/5
Included in
GPER as a Therapeutic Target in Breast Cancer: Pharmacologic Inhibition and Microbiome Associations
Background: The G protein–coupled estrogen receptor (GPER) mediates rapid estrogen signaling that promotes proliferation, migration, and therapeutic resistance in breast cancer, including in hormone receptor–negative subtypes. Notably, standard endocrine therapies may inadvertently activate GPER, highlighting the need for direct targeting of this pathway. The objectives of this study were to evaluate GPER as a therapeutic target using pharmacologic modulators and to determine how GPER-driven tumor behavior relates to tumor microbiome composition across breast cancer subtypes.
Methods: Breast cancer cell lines representing Luminal A (MCF7), Luminal B (BT474), HER2-enriched (SKBR3), and triple-negative (HCC38, MDA-MB-453, MDA-MB-231) subtypes were treated with Ormeloxifene (ORM). Effects on cell morphology and proliferation were assessed using MTT assays to determine dose-response relationships and IC₅₀ values. Cell migration and clonogenic survival were evaluated using wound healing and colony formation assays. GPER protein levels were assessed by Western blot. GPER signaling activity was evaluated using fluorescence-based intracellular calcium imaging following stimulation with the GPER agonist G1 and inhibition with ORM or the antagonist G36. For microbiome analysis, 16S rRNA sequencing was performed on breast cancer tissues to evaluate bacterial abundance, alpha and beta diversity, and subtype-specific taxonomic distributions. Additional analyses examined microbial biomarkers associated with metastatic status, age, and molecular subtype. The effects of CDK and PARP inhibitors are also evaluated in breast cancer models in the context of GPER-targeted therapy. Statistical analyses included multigroup comparisons and diversity metrics.
Results: Ormeloxifene induced marked, dose-dependent growth inhibition across all breast cancer subtypes tested, with an approximate IC₅₀ of 10 μM. ORM significantly reduced wound closure and colony formation and produced visible alterations in cell morphology. Western blot analysis demonstrated reduced GPER protein levels following ORM treatment. Functional assays showed that G1-induced calcium mobilization was effectively blocked by ORM pretreatment and by G36, confirming inhibition of GPER-mediated signaling. Microbiome profiling revealed distinct bacterial compositions among molecular subtypes, with significant differences in alpha and beta diversity, Firmicutes/Bacteroidetes ratios, and subtype-specific dominant taxa. Specific microbial species were identified as biomarkers associated with metastatic disease, younger age (< 50), and aggressive tumor subtypes. These datasets also provide a framework for interpreting responses to CDK and PARP inhibitors within GPER-defined tumor contexts.
Conclusions: GPER is a therapeutically actionable driver of breast cancer progression across multiple subtypes. Ormeloxifene effectively suppresses GPER expression and signaling, resulting in broad anti-tumor activity. Integration of tumor microbiome profiles with GPER signaling reveals additional layers of biological heterogeneity that may inform personalized therapeutic strategies. Evaluation of CDK and PARP inhibitors within this GPER-centered framework further expands the translational relevance of this targeting strategy.
