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Updated: Aug 17, 2025
Isolation and Functional Assessment of Human Breast Cancer Stem Cells from Cell and Tissue Samples
Published on: October 2, 2020
DRD1 and DRD4 are differentially expressed in breast tumors and breast cancer stem cells: pharmacological
Arely Rosas-Cruz1,2, Nohemí Salinas-Jazmín1, Anahí Valdés-Rives1
1Departamento de Farmacología, Facultad de Medicina, Universidad Nacional Autónoma de México (UNAM), CDMX, México.
Background:
Abnormal expression of dopamine receptors (DRs) has been described in multiple tumors, but their roles in breast cancer are inconclusive or contradictory since evidence of pro- and anti-tumoral effects have been reported. Herein, we analyzed the expression of DRs in breast cancer, especially in the subpopulation of cancer stem cells (CSCs), and evaluated the functional role of the receptors by pharmacological targeting.
Methods:
Expression of DRD1, DRD2, DRD3, DRD4 and DRD5 was investigated in human breast tumors and cancer cell lines using public databases. Correlation between gene expression and clinical outcome was studied by Kaplan-Mayer analyses. By flow cytometry, we assessed DRD1, DRD2, and DRD4 expression in cultures of MCF-7 (luminal) and MDA-MB-231 (triple-negative) cells. Using the previously reported SORE6 reporter system we examined the differential expression of DRD1, DRD2, and DRD4 in CSCs and tumor-bulk cells. The effect of pharmacological modulation of DRs on stemness and cell migration was studied by quantification of the reporter-positive fraction and wound healing assays, respectively.
Results:
DRD1, DRD2 and DRD4 transcripts were expressed in breast tumors. DRD4 was overexpressed compared to normal tissue and showed prognostic value. DRD1, DRD2 and DRD4 transcripts were also found in MCF-7 and MDA-MB-231 cells, but only DRD1 and DRD4 proteins were detected. DRD4 was underexpressed in CSCs compared to tumor-bulk cells, whereas DRD1 was found only in the CSCs fraction, suggesting that those receptors may have relevance in stemness control. Subtoxic concentrations of DRD1-targeting compounds did not induced significant changes in the CSCs pool. On the other hand, DRD4 inhibition by Haloperidol slightly increased the CSCs content but also reduced cell migration.
Conclusions:
Pharmacological modulation of DRD1 in MCF-7 or MDA-MB-231 cells seems to be irrelevant for stemness maintenance. DRD4 reduced expression in breast CSCs or its inhibition by Haloperidol favors CSCs-pool expansion. DRD4 inhibition can also reduce cell migration, indicating that DRD4 plays different roles in stem and non-stem breast cancer cells.
Insights
Dopamine receptors (DRs) play complex roles in breast cancer. DRD4 is underexpressed in cancer stem cells (CSCs) and its inhibition expands the CSC pool but reduces migration, suggesting distinct functions in stem and non-stem cells.
Area of Science:
- Oncology
- Pharmacology
- Molecular Biology
Background:
- Dopamine receptors (DRs) exhibit abnormal expression in various tumors, but their specific roles in breast cancer remain debated, with conflicting reports on pro- and anti-tumoral effects.
- This study investigates DR expression in breast cancer, focusing on cancer stem cells (CSCs) and evaluating the functional impact of pharmacological targeting.
Purpose of the Study:
- To analyze dopamine receptor expression in breast tumors and cancer stem cells.
- To evaluate the functional role of dopamine receptors in breast cancer stemness and migration through pharmacological modulation.
Main Methods:
- Investigated expression of DRD1-5 in human breast tumors and cell lines using public databases and Kaplan-Meier analyses.
- Assessed DRD1, DRD2, and DRD4 protein expression in MCF-7 and MDA-MB-231 cells via flow cytometry.
- Examined differential DRD1, DRD2, and DRD4 expression in CSCs versus tumor-bulk cells using a reporter system.
- Studied the effects of DR modulation on stemness and cell migration using reporter assays and wound healing assays.
Main Results:
- DRD1, DRD2, and DRD4 transcripts were detected in breast tumors; DRD4 overexpression correlated with prognosis.
- DRD1 and DRD4 proteins were found in breast cancer cell lines, with DRD4 underexpressed and DRD1 specifically expressed in CSCs.
- DRD4 inhibition increased CSC content and reduced cell migration, while DRD1 modulation showed no significant effect on stemness.
Conclusions:
- Pharmacological targeting of DRD1 does not significantly impact stemness maintenance in breast cancer cells.
- DRD4 plays distinct roles in breast cancer, with its reduced expression in CSCs and subsequent inhibition favoring CSC expansion while also decreasing cell migration.
