CCR9-CCL25 Interactions Promote Cisplatin Resistance in Breast Cancer
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Johnson-Holiday et al. World Journal of Surgical Oncology 2011, 9:46 http://www.wjso.com/content/9/1/46 WORLD JOURNAL OF SURGICAL ONCOLOGY RESEARCH Open Access CCR9-CCL25 interactions promote cisplatin resistance in breast cancer cell through Akt activation in a PI3K-dependent and FAK-independent fashion Crystal Johnson-Holiday1, Rajesh Singh1, Erica L Johnson1, William E Grizzle2, James W Lillard Jr1 and Shailesh Singh1* Abstract Background: Chemotherapy heavily relies on apoptosis to kill breast cancer (BrCa) cells. Many breast tumors respond to chemotherapy, but cells that survive this initial response gain resistance to subsequent treatments. This leads to aggressive cell variants with an enhanced ability to migrate, invade and survive at secondary sites. Metastasis and chemoresistance are responsible for most cancer-related deaths; hence, therapies designed to minimize both are greatly needed. We have recently shown that CCR9-CCL25 interactions promote BrCa cell migration and invasion, while others have shown that this axis play important role in T cell survival. In this study we have shown potential role of CCR9-CCL25 axis in breast cancer cell survival and therapeutic efficacy of cisplatin. Methods: Bromodeoxyuridine (BrdU) incorporation, Vybrant apoptosis and TUNEL assays were performed to ascertain the role of CCR9-CCL25 axis in cisplatin-induced apoptosis of BrCa cells. Fast Activated Cell-based ELISA (FACE) assay was used to quantify In situ activation of PI3Kp85,AktSer473, GSK-3bSer9 and FKHRThr24 in breast cancer cells with or without cisplatin treatment in presence or absence of CCL25. Results: CCR9-CCL25 axis provides survival advantage to BrCa cells and inhibits cisplatin-induced apoptosis in a PI3K-dependent and focal adhesion kinase (FAK)-independent fashion. Furthermore, CCR9-CCL25 axis activates cell- survival signals through Akt and subsequent glycogen synthase kinase-3 beta (GSK-3b) and forkhead in human rhabdomyosarcoma (FKHR) inactivation. These results show that CCR9-CCL25 axis play important role in BrCa cell survival and low chemotherapeutic efficacy of cisplatin primarily through PI3K/Akt dependent fashion. Keywords: chemokine breast cancer, CCR9, CCL25, cisplatin resistance Introduction apoptosis. Cancer cells develop resistance to chemother- Breast cancer (BrCa) is second leading cause of cancer apy primarily by inactivating apoptotic factors and/or related deaths among women after lung cancer [1]. It is enhancing cell survival pathways [3]. estimated that 207,090 women will be diagnosed with Chemokines are a group of small proteins (8 - 10 BrCa in 2010 and 39,480 will die from this disease in kDa), structurally related molecules that regulate traf- United States [1]. Cisplatin and its analogues have been ficking of lymphocytes through interactions with a sub- widely used to treat human cancers including BrCa [2]. set of seven-transmembrane G-protein coupled Unfortunately, many tumors become resistant to cispla- receptors [4]. To this end, we have recently shown sig- tin, which is characterized by decreased susceptibility to nificantly higher expression of CCR9 in ovarian and prostate cancer cell lines and tumors [5,6]. CCR9- CCL25 interactions known to support T cells survival * Correspondence: [email protected] 1Department of Microbiology, Biochemistry and Immunology, Morehouse during thymic maturation by inhibiting apoptosis School of Medicine, 720 Westview Drive SW, Atlanta, GA 30310 USA through Akt/protein kinase B activation, which is PI3K- Full list of author information is available at the end of the article © 2011 Johnson-Holiday et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Johnson-Holiday et al. World Journal of Surgical Oncology 2011, 9:46 Page 2 of 7 http://www.wjso.com/content/9/1/46 and Gai protein-dependent [7,8]. Indeed, the PI3K/Akt Vybrant apoptosis assay anti-apoptotic and survival pathway plays a crucial role BrCa cells were cultured in RPMI-1640 media with 5 in cisplatin resistance [9]. FAK has also been shown to μg/ml of cisplatin (IC50), along with no additions or 100 support anti-apoptotic mechanisms through Akt signal- ng/mL of CCL25 or 1 μg/mL of anti-CCR9 Ab or 100 ing [10]. Chemokine receptors may also aggregate with ng/mL of CCL25 plus 1 μg/mL of anti-CCR9 Ab for 24 integrins following stimulation to promote FAK hours. The cells were harvested and washed in ice-cold phosphorylation. PBS. Cells (105 cells/mL) were stained with Annexin-V This study investigates the role of CCR9-CCL25 inter- and propidium iodide (PI) using the Vybrant apoptosis actions and requirement for PI3K and FAK activation in assay Kit #3 (Invitrogen) according to manufacturer’s BrCa cell survival and cisplatin resistance. We show for protocol. The stained cells were analyzed by flow cyto- the first time that CCR9-CCL25 interactions provide metry using UV/488 nm dual excitation and measuring protection from cisplatin-induced BrCa cell death. We the fluorescence emission at approximately 530 nm and also show that CCR9-CCL25 interaction promotes cell 575 nm. proliferation and upregulated anti-apoptotic signaling, which is mediated by the PI3K/Akt survival pathway, Terminal Transferase dUTP Nick End Labeling (TUNEL) independent of FAK. These studies suggest that the Assay expression of functional CCR9 may facilitate BrCa cell BrCa cells were cultured with 0 or 5 μg/ml (IC50)ofcis- survival and low chemotherapeutic response. platin, along with no additions or 100 ng/mL of CCL25 plus 1 μg/mL of anti-CCR9 or isotype control antibodies Materials and methods for 24 hours. Apoptosis was measured by TUNEL assay Cell culture (Millipore) according to the manufacturer’s instructions. Human BrCa cell lines, MDA-MB-231 and MCF-7, were Briefly, following treatment the cells were fixed with 4% obtained from ATCC. These cells were cultured in paraformaldehyde in 0.1 M NaH2PO4,pH7.4for15 RPMI-1640 media (Mediatech, Inc.) supplemented with minutes. After washing in PBS three times, the cells 10% fetal bovine serum (FBS; Sigma) at 37°C with 5% were incubated with 0.05% Tween-20 in PBS for 15 CO2. Prior to each experiment, cells were cultured for minutes. After washing in PBS, the cells were incubated 24 hours in RPMI 1640 with 1% FBS to serum starve with TdT end-labelling cocktail for 60 minutes. Termi- the cells. nation buffer was added to stop the reaction. After washing 4 times in PBS, cells were blocked for 20 min- Bromodeoxyuridine incorporation assay utes and stained with avidin-fluorescein isothiocyanate BrCa cells (105) were cultured alone or with 100 ng/mL (FITC) solution for 30 minutes. After washing with PBS CCL25 + 1 μg/mL of isotype control antibody or 100 3 times, fluorescence plate reader quantified the fluores- ng/mL CCL25 + 1 μg/mL anti-CCR9 antibody (clone cence of TUNEL positive cells. 112509, R&D Systems) for 24 hours with 0, 0.1, 1, 2, 5, 10, 25, or 50 μg/mL of cisplatin. Incorporation of bro- Fast activated cell-based ELISA (FACE) modeoxyuridine (BrdU) into newly synthesized DNA The levels of total and active (phosphorylated) PI3Kp85, permits indirect detection of rapidly proliferating cells. AktSer473,GSK-3bSer9,andFKHRThr24 were quantified Hence, this assay was used according to manufacturer’s using Fast Activated Cell-based ELISA (FACE) assays instructions to estimate BrCa cell growth. Briefly, cells (Active Motif) according to the manufacturer’sinstruc- were treated with BrdU for 18 hours at 37°C. Media tions. Briefly, cells were cultured in 96-well plates one containing labelling solution was removed and cells day prior to manipulation. BrCa cells were cultured in were washed twice with media containing 10% serum. serum-free media with 0 or 5 μg/ml of cisplatin or 100 BrCa cells were fixed with 200 μL of fixative solution ng/ml of CCL25 or 5 μg/mL of cisplatin with 100 ng/ for 30 minutes at ~25°C and washed as before. Next, mL of CCL25 for 24 hours. In addition, cells were trea- cells were incubated with 100 μL of nuclease solution ted with or without kinase inhibitors of PI3K (wortman- for 30 minutes at 37°C and washed 3 times. Subse- nin; Sigma) and FAK (PF-573, 228;Pfizer). quently, 100 μL of anti-BrdU antibody was added, incu- bated for 30 minutes at 37°C, and washed 3 times. BrdU Statistics incorporation by BrCa cells was detected by peroxidase Thedatawerecomparedusingatwo-tailedStudent’st substrate reaction. After the extinction of this reaction, test and expressed as the mean ± SE. The results were the samples were measured in a micro plate reader at analyzed using the Statview II program (Abacus Con- 405 nm with a reference wavelength at approximately cepts, Inc., Berkeley CA) and were labeled statistically 490 nm. significant if p values were < 0.01. Johnson-Holiday et al. World Journal of Surgical Oncology 2011, 9:46 Page 3 of 7 http://www.wjso.com/content/9/1/46 Results cells co-cultured with CCL25 displayed significantly low Effects of CCL25 on cisplatin-induced growth inhibition apoptotic or TUNEL-positive events, which was abro- CCL25 significantly enhanced the growth of MDA-MB- gated after CCR9 blockade. 231 cells in comparison to untreated (cisplatin-free BrCa) cells (Figure 1). While cisplatin concentrations of CCR9-CCL25-interactions lead to PI3K p85, Akt, GSK-3b ≤ 1 μg/mL had no major effect on either CCL25-treated and FKHR activation or untreated BrCa cell growth, 2 μg/mL of cisplatin To identify the cellular signals involved in cisplatin reduced cell proliferation of untreated, but not CCL25- resistance mediated by CCR9-CCL25 interaction, in situ treated cells. In fact, CCL25 significantly protected cis- PI3K p85, Akt, GSK-3b, and FKHR phosphorylation platin (< 5 μg/mL)-mediated growth inhibition.