Immune-mediated Modulation of Breast Cancer Growth and Metastasis by the Chemokine Mig (CXCL9) in a Murine Model

Abstract

Current immunotherapies are limited by several factors, including the failure to recruit sufficient numbers of immune effector cells to tumors. The chemokine monokine induced by gamma-interferon (Mig; CXCL9) attracts activated T cells and natural killer (NK) cells bearing the chemokine receptor CXCR3. We investigated Mig as an immunotherapeutic agent in a syngeneic murine model of metastatic breast cancer. We transfected the highly malignant murine mammary tumor cell line 66.1 to stably express murine Mig cDNA. Immune-competent mice injected with Mig-expressing tumor cells developed smaller local tumors and fewer lung metastases, and they survived longer than mice injected with vector-control tumor cells. Mig-mediated inhibition of local tumor growth was lost in the absence of host T cells. Mig-transduced tumors had increased numbers of CD4 T cells compared with vector-control tumors, consistent with the T-cell chemoattractant property of Mig, and many tumor-infiltrating host cells expressed CXCR3. NK cells had not been examined previously as a possible effector cell in Mig-based therapies. Our studies now show that NK cells are critical to the mechanism by which Mig limits metastasis. Inhibition of angiogenesis was not implicated as a mechanism of Mig-mediated therapy in this model. These studies support the hypothesis that by manipulating the Mig-CXCR3 gradient, it is possible to direct host immune effector cells to tumors, curtailing both local tumor growth and metastasis. These studies also implicate host NK cells as an additional effector cell critical for Mig-mediated control of metastasis.

Homeobox D10 Gene, a Candidate Tumor Suppressor, Is Downregulated through Promoter Hypermethylation and Associated with Gastric Carcinogenesis

“…Numerous genes are altered significantly by ectopic expression of HoxD10 with cDNA microarray analysis. These candidate targets have been reported to participate in cellular growth, apoptosis, adhesion and angiogenesis (34)(35)(36)(37)(38)(39)(40)(41). We further validated that HCLS1, ANP32A, PDGFRL, IGFBP3 and CXCL9 were upregulated, while RAC2, NTS, KRT5 and TUSC3 downregulated by qPCR analysis.…”

“…Thus, these results support our observation that HoxD10 modulates several targets, at least including IGFBP3, ANP32A and HCLS1, that mediate caspase activation and induce cell apoptosis in gastric cancer. In addition to the regulation of apoptotic pathways, ectopic expression of HoxD10 upregulates CXCL9, an inhibitor of tumor growth and metastasis (40). RAC2, Ras-related Rho GTPases, which was downregulated by HoxD10 in our observation, enhances cell survival and migration (41).…”

CXCR3 expression is associated with poor survival in breast cancer and promotes metastasis in a murine model

“…The mammary tumor cells used for the current studies produce little, if any, CXCR3 ligand except when stimulated in vitro with IFN-g. We have shown, however, that forced overexpression of CXCL9 leads to marked inhibition of both local and metastatic tumor growth (7). This therapeutic effect is mediated by host T-cell and NK cell infiltration into the tumor.…”

“…We have previously shown that control of tumor metastasis in this model is highly dependent on functioning NK cells and, in some cases, on IFN-g (7,8). To determine if NK cells play a role in the reduced metastasis by CXCR3 knockdown, we compared the lung colonizing abilities of 66.1-vector and 66.1shCXCR3 cells in normal BALB/cByJ mice, BALB/cByJ mice depleted of NK cells, and mice mutant for IFN-g. Figure 4A and B confirms the data in Fig.…”

Cross-Talk of Breast Cancer Cells with the Immune System

“…CXCR3, a chemokine receptor expressed by activated Th1 and effector CD8 T and natural killer (NK) cells, binds to three chemokines, CXCL9, CXCL10 and CXCL11. Overexpression of CXCL10 (also known as interferon (IFN)-γ inducible protein 10, IP-10), or CXCL9 (also known as monokine induced by IFN-γ, Mig) by genetic engineering of tumor cells in experimental mouse tumor models enhanced recruitment of T and NK cells and promoted immune-mediated tumor rejection (Luster and Leder, 1993;Walser et al, 2007). However, CXCR3 is also expressed by human and mouse breast cancer cell lines (Goldberg-Bittman et al, 2004;Walser et al, 2006), and more recently it was found in all human primary breast cancers tested (N=75).…”