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Targeting mTOR to overcome resistance to hormone and CDK4/6 inhibitors in ER-positive breast cancer models.

ABSTRACT: Resistance to therapy remains a major obstacle in cancer management. Although treatment with hormone and CDK4/6 inhibitors is successful in luminal breast cancer, resistance to these treatments is frequent, highlighting the need for novel therapeutic strategies to delay disease progression and improve patient survival. Here, we assessed the mechanisms of acquired resistance using T47D and MCF-7 tamoxifen- and palbociclib-resistant cell-line variants in culture and as xenografts, and patient-derived cells (PDCs) obtained from sensitive or resistant patient-derived xenografts (PDXs). In these models, we analyzed the effect of specific kinase inhibitors on survival, signaling and cellular aggressiveness. Our results revealed that mTOR inhibition is more effective than PI3K inhibition in overcoming resistance, irrespective of PIK3CA mutation status, by decreasing cell proliferation and tumor growth, as well as reducing cell migration and stemness. Moreover, a combination of mTOR and CDK4/6 inhibitors may prevent pathway reactivation downstream of PI3K, interfering with the survival of resistant cells and consequent tumor escape. In conclusion, we highlight the benefits of incorporating mTOR inhibitors into the current therapy in ER + breast cancer. This alternative therapeutic strategy not only enhances the antitumor response but may also delay the emergence of resistance and tumor recurrence.

SUBMITTER: Rodriguez MJ

PROVIDER: S-EPMC9932145 | biostudies-literature | 2023 Feb

REPOSITORIES: biostudies-literature

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Targeting mTOR to overcome resistance to hormone and CDK4/6 inhibitors in ER-positive breast cancer models.

Rodriguez María Jimena MJ Perrone María Cecilia MC Riggio Marina M Palafox Marta M Salinas Valeria V Elia Andrés A Salgueiro Natali Daiana ND Werbach Andrea Eugenia AE Marks María Paula MP Kauffman Marcelo A MA Vellón Luciano L Serra Violeta V Novaro Virginia V

Scientific reports 20230215 1

Resistance to therapy remains a major obstacle in cancer management. Although treatment with hormone and CDK4/6 inhibitors is successful in luminal breast cancer, resistance to these treatments is frequent, highlighting the need for novel therapeutic strategies to delay disease progression and improve patient survival. Here, we assessed the mechanisms of acquired resistance using T47D and MCF-7 tamoxifen- and palbociclib-resistant cell-line variants in culture and as xenografts, and patient-deri ...[more]

PMID: 36792625

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Project description:BackgroundCDK4/6 inhibitors have significantly improved the survival of patients with HR-positive/HER2-negative breast cancer, becoming a first-line treatment option. However, the development of resistance to these inhibitors is inevitable. To address this challenge, novel strategies are required to overcome resistance, necessitating a deeper understanding of its mechanisms. Recent research has identified several dysregulated genes in CDK4/6 inhibitors-resistant breast cancer, but the underlying mechanism is complex due to tumor heterogeneity and warrants further investigation.MethodsRNA sequencing and KEGG pathway analysis was carried out to identify the mainly dysregulated genes in CDK4/6 inhibitors-resistant breast cancer cells. The effects of CXCR4 knockdown and overexpression via siRNAs and plasmids transfection were examined by mammosphere formation, RT-qPCR, flow cytometry, MTT and colony formation assays. The regulation mechanisms were analyzed by RT-qPCR, western blotting and immunofluorescence experiments. Mouse xenografts were used to analyze the role of CXCR4 in regulation palbociclib sensitivity in vivo. Additionally, we collected the clinical samples and performed immunohistochemistry to analyze the clinical significance of CXCR4.ResultsIn our study, we focused on cancer stem cells, a critical contributor to cancer metastasis and therapy resistance, and detected an upregulation of stemness in our established palbociclib-resistant ER-positive breast cancer cells. Additionally, our research pinpointed CXCR4 as a pivotal gene responsible for maintaining cancer stemness and promoting palbociclib resistance. Mechanistically, CXCR4 activates the WNT5A/β-catenin signaling pathway by enhancing the expression of WNT5A and β-catenin, facilitating the nuclear translocation of β-catenin protein. Targeting CXCR4 using siRNAs or small molecular inhibitors effectively reduces cancer stemness and reverses palbociclib resistance both in vitro and in vivo. Clinical sample analysis further underscores the overactivation of the CXCR4/WNT5A/β-catenin axis in palbociclib-resistant breast cancer, suggesting CXCR4 as a potential biomarker for predicting resistance to CDK4/6 inhibitors.ConclusionsCollectively, our study demonstrates that CXCR4 overexpression plays a vital role in maintaining breast cancer stemness and promoting resistance to CDK4/6 inhibitors through the activation of the WNT5A/β-catenin pathway. Targeting CXCR4 may offer a promising therapeutic approach for advanced CDK4/6 inhibitor-resistant ER-positive breast cancer.

Dataset Information

Targeting mTOR to overcome resistance to hormone and CDK4/6 inhibitors in ER-positive breast cancer models.

Publications

Targeting mTOR to overcome resistance to hormone and CDK4/6 inhibitors in ER-positive breast cancer models.

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