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Pranlukast Antagonizes CD49f and Reduces Stemness in Triple-Negative Breast Cancer Cells
Inés Velázquez-Quesada1,2, Angel J Ruiz-Moreno1,3,4, Diana Casique-Aguirre1
1Department of Pharmacology, School of Medicine, Universidad Nacional Autónoma de México, Mexico City, Mexico.
Introduction:
Cancer stem cells (CSCs) drive the initiation, maintenance, and therapy response of breast tumors. CD49f is expressed in breast CSCs and functions in the maintenance of stemness. Thus, blockade of CD49f is a potential therapeutic approach for targeting breast CSCs. In the present study, we aimed to repurpose drugs as CD49f antagonists.
Materials And Methods:
We performed consensus molecular docking using a subdomain of CD49f that is critical for heterodimerization and a collection of pharmochemicals clinically tested. Molecular dynamics simulations were employed to further characterize drug-target binding. Using MDA-MB-231 cells, we evaluated the effects of potential CD49f antagonists on 1) cell adhesion to laminin; 2) mammosphere formation; and 3) cell viability. We analyzed the effects of the drug with better CSC-selectivity on the activation of CD49f-downstream signaling by Western blot (WB) and co-immunoprecipitation. Expressions of the stem cell markers CD44 and SOX2 were analyzed by flow cytometry and WB, respectively. Transactivation of SOX2 promoter was evaluated by luciferase reporter assays. Changes in the number of CSCs were assessed by limiting-dilution xenotransplantation.
Results:
Pranlukast, a drug used to treat asthma, bound to CD49f in silico and inhibited the adhesion of CD49f+ MDA-MB-231 cells to laminin, indicating that it antagonizes CD49f-containing integrins. Molecular dynamics analysis showed that pranlukast binding induces conformational changes in CD49f that affect its interaction with β1-integrin subunit and constrained the conformational dynamics of the heterodimer. Pranlukast decreased the clonogenicity of breast cancer cells on mammosphere formation assay but had no impact on the viability of bulk tumor cells. Brief exposure of MDA-MB-231 cells to pranlukast altered CD49f-dependent signaling, reducing focal adhesion kinase (FAK) and phosphatidylinositol 3-kinase (PI3K) activation. Further, pranlukast-treated cells showed decreased CD44 and SOX2 expression, SOX2 promoter transactivation, and in vivo tumorigenicity, supporting that this drug reduces the frequency of CSC.
Conclusion:
Our results support the function of pranlukast as a CD49f antagonist that reduces the CSC population in triple-negative breast cancer cells. The pharmacokinetics and toxicology of this drug have already been established, rendering a potential adjuvant therapy for breast cancer patients.
Insights
Pranlukast, an asthma drug, effectively targets cancer stem cells (CSCs) in triple-negative breast cancer by blocking CD49f. This repurposed drug reduces CSC frequency and shows potential as an adjuvant therapy.
Area of Science:
- Integrin signaling in cancer biology
- Drug repurposing for oncology
- Cancer stem cell targeting strategies
Background:
- Cancer stem cells (CSCs) are crucial drivers of breast tumor initiation, maintenance, and therapeutic resistance.
- CD49f is a marker and functional mediator of stemness in breast CSCs.
- Targeting CD49f presents a promising therapeutic strategy for eliminating breast CSCs.
Purpose of the Study:
- To identify and repurpose existing drugs as antagonists for CD49f.
- To evaluate the efficacy of potential CD49f antagonists in preclinical models of breast cancer.
Main Methods:
- Consensus molecular docking and molecular dynamics simulations to assess drug-target interactions with CD49f.
- In vitro assays using MDA-MB-231 cells to evaluate effects on cell adhesion, mammosphere formation, and viability.
- Analysis of CD49f-downstream signaling, stem cell marker expression (CD44, SOX2), and in vivo tumor-initiating capacity.
Main Results:
- Pranlukast, an asthma medication, demonstrated in silico binding to CD49f and inhibited cell adhesion to laminin.
- Pranlukast reduced breast cancer cell clonogenicity and mammosphere formation without affecting bulk tumor cell viability.
- Treatment with pranlukast decreased CSC markers (CD44, SOX2), SOX2 promoter activity, and in vivo tumor formation.
Conclusions:
- Pranlukast functions as a CD49f antagonist, effectively reducing the CSC population in triple-negative breast cancer.
- The established pharmacokinetic and toxicological profiles of pranlukast support its potential as an adjuvant therapy for breast cancer.
