Cellular & Molecular Immunology (2013) 10, 303–310 ß 2013 CSI and USTC. All rights reserved 1672-7681/13 $32.00 www.nature.com/cmi REVIEW CCL5 as a potential immunotherapeutic target in triple-negative breast cancer Dandan Lv1, Yan Zhang2, Ha-Jeong Kim2, Lixing Zhang1 and Xiaojing Ma1,2 Breast cancer (BC) is a leading cause of mortality among women in the world. To date, a number of molecules have been established as disease status indicators and therapeutic targets. The best known among them are estrogen receptor-a (ER-a), progesterone receptor (PR) and HER-2/neu. About 15%–20% BC patients do not respond effectively to therapies targeting these classes of tumor-promoting factors. Thus, additional targets are strongly and urgently sought after in therapy for human BCs negative for ER, PR and HER-2, the so-called triple-negative BC (TNBC). Recent clinical work has revealed that CC chemokine ligand 5 (CCL5) is strongly associated with the progression of BC, particularly TNBC. How CCL5 contributes to the development of TNBC is not well understood. Experimental animal studies have begun to address the mechanistic issue. In this article, we will review the clinical and laboratory work in this area that has led to our own hypothesis that targeting CCL5 in TNBCs will have favorable therapeutic outcomes with minimal adverse impact on the general physiology. Cellular & Molecular Immunology (2013) 10, 303–310; doi:10.1038/cmi.2012.69; published online 4 February 2013 Keywords: triple negative breast cancer; CCL5; myeloid derived suppressor cell; immunotherapy CCL5 IN IMMUNITY AND IN INFLAMMATORY DISEASES nophils and basophils. In collaboration with certain cytokines Chemokines are small soluble proteins that act as molecular that are released by T cells such as IL-2 and IFN-c, CCL5 also signals to induce cellular migration during inflammation. induces the activation and proliferation of particular natural- Chemokines and chemokine receptors are expressed by many killer cells to generate CC chemokine-activated killer cells.7 types of cancers cells. Locally produced chemokines can induce CCL5 produced by CD81 T cells and other immune cells has inflammatory tumor-infiltrating cells, facilitate angiogenesis, been shown to inhibit HIV entry into target cells.8 The activities promote growth or survival, and stimulate tumor cell meta- of CCL5 are mediated through its binding to CCR1, CCR3 and stasis.1–3 CCR5.9 CC chemokine ligand 5 (CCL5), also known as RANTES Genetic evidence exists that links CCL5 with numerous (Regulated upon Activation, Normal T-cell Expressed, and human diseases, such as coronary artery disease,10 multiple Secreted), belongs to the CC chemokine family whose mem- sclerosis,11 rheumatoid arthritis,12,13 asthma and atopy,14–17 bers include monocyte chemoattractant protein (MCP)-1, atopic eczema/dermatitis syndrome, atopic dermatitis,18 hep- MCP-2, MCP-3, I-309, macrophage inhibitory protein-1a atitis C virus infection,19,20 heart graft rejection21 and systemic and macrophage inhibitory protein-1b. CCL5 was first iden- lupus erythematosus.22,23 tified in a search for genes that were expressed differen- tially in activated T cells but not in B cells.4 In T lymphocytes, CCL5 AND HUMAN BREAST CANCER (BC) CCL5 expression is regulated by Kruppel-like factor 13.4–6 The human CCL5 gene is located on the long arm of chro- CCL5 is also expressed in macrophages, platelets, synovial mosome 17,24 the same area Her2/neu is encoded and an area fibroblasts, tubular epithelium and certain types of tumor cells. amplified in 30% BC patients.25 Tumor-derived CCL5 is CCL5 plays an active role in recruiting a variety of leukocytes detected in many clinical specimens of breast and cervical can- into inflammatory sites including T cells, macrophages, eosi- cers; greater plasma levels in patients with progressive and 1Sheng Yushou Center of Cell Biology and Immunology, School of Life Science and Biotechnology, Shanghai Jiaotong University, Shanghai, China and 2Department of Microbiology and Immunology, Weill Cornell Medical College, New York, NY, USA Correspondence: Dr XJ Ma, Sheng Yushou Center of Cell Biology and Immunology, School of Life Science and Biotechnology, 800 Dongchuan Road, Shanghai Jiaotong University, Shanghai 20040, China E-mail: [email protected] or E-mail: [email protected] Received: 30 September 2012; Revised 19 November 2012; accepted: 20 November 2012 CCL5 in triple-negative breast cancer DD Lv et al 304 more advanced disease than those in remission,26–28 and it tumor development induced by Wnt-1 expression is facilitated constitutes a prominent part of a poor prognosis signature by other genetic lesions such as inactivation of p53 and over- of inflammatory BC.29,30 An analysis of large core needle expression of Fgf-3.37 biopsies of 113 invasive breast carcinomas revealed that the concentration of CCL5 was significantly higher in the groups TRIPLE NEGATIVE BC of patients with axillary lymph node metastasis than those ER-a-, PR- and HER-2/neu-negative BC, or triple-negative BC without.31 Most BC-derived cell lines spontaneously produce (TNBC), is a highly malignant disease that traditionally lacks a large amounts of CCL5, and the incidence of CCL5 expression clearly definable therapeutic target. It was originally described detected in tissue sections of breast carcinomas is considerably by Perou et al. as distinct molecular subgroups of BCs differ- higher than in normal duct epithelial cells or in those of benign entiated by their gene expression profiles associated with pro- breast lumps.32 CCL5 expression was speculated to be indi- gnosis. These subgroups comprised of a normal breast–like cative of an ongoing, but as yet undetectable, malignant pro- group, the basal epithelial-like group, an ERBB2-overexpres- cess.32 A Cox proportional hazard model-based univariate sing group and the ER-positive luminal A and B groups.38,39 analysis of 142 BC patients indicated little predictive value of Based on their global gene expression profiles, about 70% of CCL5 for disease progression in stage I BC patients. In contrast, breast tumors identified as triple negative by immunohisto- the expression of CCL5, the absence of estrogen receptor (ER)- chemistry belong to the basal-like group of BCs.40 Inte- a and the lack of progesterone receptor (PR) expression in restingly, a large proportion of BCs arising in women with stage II patients increased significantly the risk for disease germline BRCA1 mutations exhibit the triple-negative pheno- development. Conversely, the combinations of CCL5-nega- type and also fall within the basal-like group.41 It is now a tive/ER-a-positive and CCL5-negative/PR-positive in the stage well-accepted notion that polyADP-ribose inhibition within II group as a whole were strongly correlative with an improved BRCA-deficient cancer cells can effective block the residual prognosis.33 DNA repair machinery, resulting in synthetic lethality.42 Furthermore, concomitant expression of the CCL5 and MCP-1 was observed in advanced human BC,34 suggesting 4T1, AN INFLAMMATORY MURINE TNBC MODEL tumor-promoting interactions between these two chemokines. A very commonly used immunocompetent, syngeneic and tri- By immunohistochemistry analysis for the expression of CCL2, ple negative mouse model of mammary tumor development is CCL5, IL-1b and TNF-a, Soria et al. examined four groups of the 4T1 cell line, which was first isolated from a single sponta- patients diagnosed with (i) benign breast disorders; (ii) ductal neously arising mammary tumor from a BALB/cfC3H mouse carcinoma in situ; (iii) invasive ducal carcinoma (IDC) without (murine mammary tumor virus).43 4T1 is an excellent model relapse; and (iv) IDC with relapse, respectively. The analyses system for BC research due to the oncologically and immuno- revealed significant associations between CCL2 and CCL5 and logically well-characterized tumor development. The 4T1 between IL-1b and TNF-a, respectively, in the tumor cells from tumor closely mimics human BC in its physical location, pro- ductal carcinoma in situ and IDC-without-relapse patients. liferative and metastatic characteristics.44 The growth and The expression of CCL2 and CCL5 in the IDC-with-relapse metastatic properties of 4T1 cells closely resemble stage IV group was associated with further elevated expression of IL- BC,45 and it is a TNBC.44 4T1 tumor instinctively migrates 1b and TNF-a.35 primarily through a hematogenous route to many distant In human breast tumor cells, CCL5-containing vesicles on organs including the lung, heart, bone, brain and liver.46 4T1 microtubules traffic from the endoplasmic reticulum to the is also poorly immunogenic in that only slight delays in tumor post-Golgi stage before CCL5 is released, and this process is growth against tumor challenge is attained via immunization controlled by the stiffness of the actin cytoskeleton in a manner with irradiated 4T1 cells, inadequate to protect the host.47 dependent on the (43)TRKN(46) sequence of the 40 s loop of Immune suppression in the 4T1 model has been attributed in CCL5.36 part to a signal transduction and transcription 6-dependent inhibition of the development of tumor-specific CD81 cyto- CCL5 IN EXPERIMENTAL MOUSE MAMMARY TUMORS toxic T lymphocyte activity.48 Nevertheless, 4T1 are capable of The mouse CCL5 is 68-amino acid long and highly basic, shares stimulating an immune response of the host because it has been 85% homology with human CCL5. Most human BC studies in shown that effective anti-tumor immune responses can