Research Highlight: Adipose-Derived Stem Cells and Chemoresistance in Breast Cancer
This month’s study focuses on triple negative breast cancer (TNBC) and how mesenchymal stem cells in the tumor microenvironment can influence therapeutic responses. We’re excited to feature an article from the lab of Dar-Ren Chen and others at the Comprehensive Breast Cancer Center at the Changhua Christian Hospital, Taiwan. The article was published 27 July 2017 in the journal Stem Cell Research & Therapy and includes miRNA expression data generated by the Phalanx Biotech service lab using the Human miRNA OneArray Microarray platform.
This work is important because TNBC is an aggressive type of breast cancer that often leads to chemoresistance following relapse. There is increased interest in how different cell types in the tumor microenvironment modulate tumor progression. Focus has turned to adipose tissue since it is the most abundant cell type in the breast and a potent source of stem-like cells. The role of these human adipose-derived stem cells (hAdSCs) in breast cancer is not well understood.
Characterization of hAdSCs by Flow Cytometry and Their Effect on TNBC Cells
The authors first isolate and culture hAdSCs from patients undergoing a mastectomy. Flow cytometric analyses reveal the presence of mesenchymal stem cell markers CD29, CD90, and CD105 on the surface of hAdSCs. Next, they treat MDA-MB-231 cells, a TNBC cell line, with conditioned media taken from cultured primary hAdSCs, and measure the effect of doxorubicin. Doxorubicin is a first-line chemotherapy for TNBC. Doxorubicin causes significant cell death in MDA-MB-231 cells. Interestingly, MDA-MB-231 cells treated with hAdSC conditioned media show reduced cell death following doxorubicin treatment. The authors go a step further by showing that doxorubicin resistance in MDA-MB-231 cells treated with hAdSC conditioned media is facilitated via the up-regulation of an ABC transporter. ABCG2, along with P-gp and MRP1, are potent drug efflux transporters known to be involved in the development of drug resistance. While the authors don’t find an increase in P-gp or MRP1, their focused experiments on ABCG2 consistently indicate a role for elevated ABCG2 expression in the development of doxorubicin resistance.
Chemokine Secretion by hADSCs is Involved in Doxorubicin Resistance
Previous studies have shown that cytokines and chemokines secreted by nearby cells have tumor-promoting properties. The authors therefore assume that hAdSCs are sending signals to the breast cancer cells and thereby contributing to doxorubicin resistance. They use cytokine and chemokine arrays to characterize the signaling factors being secreted into the media by hAdSCs. Among the positive hits, CXCL1, CCL5 and IL-8 are the most abundant factors identified. They aim to investigate the possible role of CXCL1 and CCL5 in hAdSCs-induced doxorubicin resistance in TNBC. They treat MDA-MB-231 cells with recombinant CXCL1 and CCL5 to see if either causes an increase in ABCG2 expression. While CCL5 fails to increase ABCG2, CXCL1 causes a 2-fold increase in ABCG2. The increase in ABCG2 brought on by CXCL1 is abrogated by co-treatment with a CXCL1 neutralizing antibody. These findings indicate that CXCL1 released by hAdSCs leads to ABCG2 up-regulation, which in turn leads to doxorubicin resistance in MDA-MB-231 TNBC cells.
MicroRNA Microarray Analysis of MDA-MB-231 Cells Treated with hAdSC Media
Using Human miRNA OneArray Microarrays, the authors seek to discover the mechanism by which CXCL1 up-regulates ABCG2 in MDA-MB-231 cells. They compare miRNA expression profiles between cells treated with hAdSC conditioned media and those treated with control media. Then they use online miRNA target prediction tools to look for which differentially expressed miRNAs are predicted to target ABCG2. They identify miR-106a-5p, miR-3656, miR-3940-5p, miR-6087, miR-4792, and miR-222-3p as potential targets of further study. They narrow the search to miR-106a-5p since it is predicted to interact with ABCG2 in multiple target prediction databases. Using qPCR, they find that treatment with hAdSC conditioned media causes a 2-fold decrease in miR-106a-5p expression.
To further fill out the signaling pathway, the authors look at miR-106a-5p expression in MDA-MB-231 cells following treatment with recombinant CXCL1. They find that CXCL1 decreases miR-106a expression in a dose-dependent manner. Furthermore, treatment with the CXCL1-neutralizing antibody reverses the adjustment of miR-106 expression back to normal. Interestingly, transfection of a miR-106a inhibitor into MDA-MB-231 cells dose-dependently increases ABCG2 and also reduces doxorubicin sensitivity.
In summary, the authors present an interesting model whereby CXCL1 secreted by hAdSCs stimulates doxorubicin resistance through miR-106a-mediated ABCG2 up-regulation. They take a genomic approach by utilizing Human miRNA OneArray Microarrays, and ultimately, their work provides a better understanding of hAdSCs in the breast cancer microenvironment. By focusing on the development of chemoresistance, this work could lead to the discovery of new therapeutic strategies to overcome drug resistance in TNBC.
At Phalanx Biotech, we specialize in ramping up your research. Please contact us if you are looking for a world-class genomics service provider. We offer services on either Agilent or our own OneArray microarray platforms. We are also experienced providers of NGS services, qPCR services, and gene expression microarray services. No matter what genomics approach you need, contact us, and we’ll be sure to accelerate your research efforts.
Yeh W-L et al. (2017). Peri-foci adipose-derived stem cells promote chemoresistance in breast cancer. Stem Cell Research & Therapy, 8:177.