Expression of CXC chemokine receptor-4 enhances the pulmonary metastatic potential of murine B16 melanoma cells

The chemokine receptors CC chemokine receptor (CCR) 7 and CXC chemokine receptor (CXCR) 4 have been implicated in cancer metastasis. To evaluate whether CXCR4 is sufficient to increase tumor metastasis in an organ-specific manner, we transduced murine B16 melanoma cells with CXCR4 (CXCR4-B16) and followed the metastatic fate of the transduced cells in both i.v. and s.c. inoculation models of metastasis. CXCR4-B16 cells demonstrated marked increases (>10-fold) in pulmonary metastasis compared with vector (pLNCX2)-B16 after i.v. and s.c. inoculation of tumor cells. The increase in metastasis could be completely inhibited by T22, a small peptide antagonist of CXCR4. As early as 24 and 48 h after i.v. injection, CXCR4-B16 cells were significantly increased in the lung compared with control B16 cells by 5- and 10-fold (P < 0.05), respectively. CXCR4-B16 cells adhered better to both dermal and pulmonary microvascular endothelial cells relative to control B16 cells. Moreover, CXCL12 promoted the growth of CXCR4-B16 cells in vitro. Whereas expression of CXCR4 in B16 cells dramatically enhanced pulmonary metastasis, metastasis to the lymph nodes, liver, and kidney was rare. Immunohistochemical staining of both primary human cutaneous melanoma and pulmonary metastases revealed CXCR4 expression. Thus, CXCR4 plays a potentially important role in promoting organ-selective metastasis, possibly by stimulating tumor adhesion to microvascular endothelial cells and by enhancing the growth of tumor cells under stress.     

CXC chemokine receptor-4 antagonist blocks both growth of primary tumor and metastasis of head and neck cancer in xenograft mouse models

Squamous cell carcinoma of the head and neck (SCCHN) metastasizes to the lymph nodes and lungs. We have generated previously an orthotopic mouse model for head and neck metastasis and did in vivo selection of SCCHN cells through four rounds of serial metastases. A subpopulation of 686LN cells with high metastatic potential (686LN-Ms) was isolated. When the highly metastatic cells were compared with their low metastatic parental cells (686LN-Ps), we found that CXC chemokine receptor-4 (CXCR4) mRNA levels were significantly higher in the 686LN-Ms cells than the 686LN-Ps cells. Interestingly, the metastatic subclones had lost epithelial morphology and acquired mesenchymal features, which were maintained during cell expansion in vitro. This was featured by decreased E-cadherin and involucrin and increased vimentin and integrin beta(1). These results imply that CXCR4 and epithelial-mesenchymal transition markers can be potential biomarkers to identify the subpopulation of cells with high metastatic potential. Using the orthotopic SCCHN animal model, we showed that anti-CXCR4 treatment suppressed primary tumor growth by inhibiting tumor angiogenesis and prevented lung metastasis. Because the reduction of metastasis seen in the treated group could have resulted from 2-fold reduction in primary tumor size compared with that in the control group, we examined the effects of the CXCR4 antagonist in an experimental metastatic animal model in which 686LN-Ms cells were i.v. injected. 686LN-Ms cells failed to metastasize in the CXCR4 antagonist-treated group, whereas they metastasized to the lungs in the control group. Our data indicate that CXCR4 is an important target to inhibit tumor progression in SCCHN.     

Clinical significance of CXC chemokine receptor-4 and c-Met in childhood rhabdomyosarcoma.

PURPOSE: The CXC chemokine receptor-4 (CXCR4)/stromal-derived factor-1 and c-Met/hepatocyte growth factor axes promote the metastatic potential of rhabdomyosarcoma cell lines in experimental models, but no data are available on their role in rhabdomyosarcoma tumors. The expressions of CXCR4 and c-Met were evaluated in primary tumors and isolated tumor cells in marrow, and were correlated with clinicopathologic variables and survival. EXPERIMENTAL DESIGN: Forty patients with recently diagnosed rhabdomyosarcoma were retrospectively enrolled. CXCR4 and c-Met expression was investigated in primary tumors by immunohistochemistry, in isolated marrow-infiltrating tumor cells using double-label immunocytology. Results were expressed as the mean percentage of immunostained tumor cells. RESULTS: CXCR4 and c-Met were expressed in >/=5% of tumor cells from 40 of 40 tumors, with 14 of 40 cases showing >/=50% of immunostained tumor cells (high expression). High CXCR4 expression correlated with alveolar histology (P = 0.006), unfavorable primary site (P = 0.009), advanced group (P < 0.001), marrow involvement (P = 0.007), and shorter overall survival and event-free survival (P < 0.001); high c-Met expression correlated with alveolar histology (P = 0.005), advanced group (P = 0.04), and marrow involvement (P = 0.02). In patients with a positive diagnosis for isolated tumor cells in marrow (n = 16), a significant enrichment in the percentage of CXCR4-positive (P = 0.001) and c-Met-positive (P = 0.003) tumor cells was shown in marrow aspirates compared with the corresponding primary tumors. CONCLUSIONS: CXCR4 and c-Met are widely expressed in both rhabdomyosarcoma subtypes and, at higher levels, in isolated marrow-infiltrating tumor cells. High levels of expression are associated with unfavorable clinical features, tumor marrow involvement and, only for CXCR4, poor outcome. In rhabdomyosarcoma, CXCR4 and c-Met represent novel exploitable targets for disease-directed therapy.     

Overexpression of the duffy antigen receptor for chemokines (DARC) by NSCLC tumor cells results in increased tumor necrosis

Background  

The Duffy antigen receptor for chemokines (DARC) is known to be a promiscuous chemokine receptor that binds a variety of CXC and CC chemokines in the absence of any detectable signal transduction events. Within the CXC group of chemokines, DARC binds the angiogenic CXC chemokines including IL-8 (CXCL8), GROα (CXCL1) and ENA-78 (CXCL5), all of which have previously been shown to be important in non-small cell lung carcinoma (NSCLC) tumor growth. We hypothesized that overexpression of DARC by a NSCLC tumor cell line would result in the binding of the angiogenic ELR+ CXC chemokines by the tumor cells themselves, and thus interfere with the stimulation of endothelial cells and induction of angiogenesis by the tumor cell-derived angiogenic chemokines.     

Growth regulated oncogene-alpha expression by murine squamous cell carcinoma promotes tumor growth, metastasis, leukocyte infiltration and angiogenesis by a host CXC receptor-2 dependent mechanism

Growth Regulated Oncogene-alpha (GRO-alpha) is an autocrine growth factor in melanoma and is a member of the C-X-C family of chemokines which promote chemotaxis of granulocytes and endothelia through binding to CXC Receptor 2. We found previously that variants of murine squamous cell carcinoma PAM 212 which grow and metastasize more rapidly in vivo constitutively express increased levels of murine GRO-alpha, designated mGRO-alpha, or KC. We have examined the possible role of mGRO-alpha expression in malignant progression of squamous cell carcinoma PAM 212 in homologous BALB/c and BALB CXC Receptor-2 deficient mice. Transfection of the PAM 212 cell line which exhibits low expression of GRO-alpha and malignant potential with a pActin-KC vector encoding mGRO-alpha enabled isolation of PAM-KC expressing cell lines. These PAM-KC transfectants displayed an increased rate of growth and metastasis in BALB/c mice, similar to the highly malignant phenotype observed in spontaneously occurring metastatic variants. Furthermore, the PAM-KC tumors showed an increase in infiltration of host leukocytes and CD31+ blood vessels, consistent with increased CXC chemokine activity. The increased growth of PAM-KC cells was attenuated in CXCR-2 deficient mice, indicating that the increased growth was dependent in part upon host cells responsive to the CXC chemokine. Together, these results show that a CXC chemokine such as GRO-alpha can promote malignant growth of murine squamous cell carcinoma by a host CXCR-2 dependent pathway. Oncogene (2000) 19, 3477 - 3486     

Endogenous retrovirus expression is required for murine melanoma tumor growth in vivo

Tumor development is a multistep process in which both genetic and epigenetic events cooperate for the emergence of a malignant clone. The possibility that endogenous retroviruses promote the expansion of a neoplastic clone by subverting immune surveillance has been proposed, but remained elusive. Here we show that knocking down-by RNA interference-an endogenous retrovirus spontaneously induced in the B16 murine melanoma results in the rejection of the tumor cells in immunocompetent mice, under conditions where control melanoma cells grow into lethal tumors. The knockdown does not modify the transformed phenotype of the cells, as measured both in vitro by a soft agar assay and in vivo by tumor cell proliferation in immunoincompetent (X-irradiated and severe combined immunodeficiency) mice. Tumor rejection can be reverted upon adoptive transfer of regulatory T cells from control melanoma-engrafted mice, as well as upon reexpression of the sole envelope gene of the endogenous retrovirus in the knocked down cells. These results show that endogenous retroviruses can be essential for a regulatory T-cell-mediated subversion of immune surveillance and could be relevant to human tumors where such elements-and especially their envelope gene-are induced.     

Enhanced targeting and killing of tumor cells expressing the CXC chemokine receptor 4 by transducible anticancer peptides

Protein transduction domains (PTDs), such as the TAT PTD, have been shown to deliver a wide variety of cargo in cell culture and to treat preclinical models of cancer and cerebral ischemia. The TAT PTD enters cells by a lipid raft-dependent macropinocytosis mechanism that all cells perform. Consequently, PTDs resemble small-molecule therapeutics in their lack of pharmacologic tissue specificity in vivo. However, several human malignancies overexpress specific receptors, including HER2 in breast cancer, GnRH in ovarian carcinomas, and CXC chemokine receptor 4 (CXCR4) in multiple malignancies. To target tumor cells that overexpress the CXCR4 receptor, we linked the CXCR4 DV3 ligand to two transducible anticancer peptides: a p53-activating peptide (DV3-TATp53C') and a cyclin-dependent kinase 2 antagonist peptide (DV3-TAT-RxL). Treatment of tumor cells expressing the CXCR4 receptor with either the DV3-TATp53C' or DV3-TAT-RxL targeted peptides resulted in an enhancement of tumor cell killing compared with treatment with nontargeted parental peptides. In contrast, there was no difference between DV3 targeted peptide and nontargeted, parental peptide treatment of non-CXCR4-expressing tumor cells. These observations show that a multidomain approach can be used to further refine and enhance the tumor selectivity of biologically active, transducible macromolecules for treating cancer.     

Differential inhibition of tumor angiogenesis by tie2 and vascular endothelial growth factor receptor-2 dominant-negative receptor mutants

Tumor growth is angiogenesis-dependent. Current evidence suggests that vascular endothelial growth factor (VEGF), a major regulator of embryonic and hypoxia-mediated angiogenesis, is necessary for tumor angiogenesis. VEGF is expressed in tumor cells in vivo, and its tyrosine kinase receptors VEGFR-1 and VEGFR-2 are up-regulated in the tumor endothelium. A second endothelial cell-specific ligand/receptor tyrosine kinase system, consisting of the tie2 receptor, its activating ligand angiopoietin-1 and the inhibitory ligand angiopoietin-2, has been characterized. We have examined 6 human primary breast-cancer samples and 4 murine breast-cancer cell lines (M6363, M6378, M6444, M6468), transplanted into nude mice, by in situ hybridization and/or Northern analysis. Expression of angiopoietin-1, angiopoietin-2 and tie2 was compared to VEGF and VEGFR-2 expression. Human tumors expressed VEGFR-2 and tie2 but varied considerably in VEGF and angiopoietin-1/-2 expression. In the murine tumor models, we observed high heterogeneity of receptor and ligand expression. M6363 and M6378 tumors were analyzed in detail because they showed different expression of components of the tie2/angiopoietin signaling system. M6363 tumors expressed VEGF, VEGFR-2 and angiopoietin-2 but not tie2 or angiopoietin-1, suggesting activation of VEGFR-2 and inhibition of tie2 signaling pathways, whereas M6378 tumors expressed VEGF, VEGFR-2, tie2 and angiopoietin-1 but little angiopoietin-2, suggesting activation of both VEGFR-2 and tie2 signaling pathways. In vivo studies using truncated dominant-negative tie2 and VEGFR-2 mutants revealed inhibition of M6363 tumor growth by 15% (truncated tie2) and 36% (truncated VEGFR-2), respectively. In contrast, M6378 tumor growth was inhibited by 57% (truncated tie2) and 47% (truncated VEGFR-2), respectively. These findings support the hypothesis that tumor angiogenesis is dependent on VEGFR-2 but suggest that, in addition, tie2-dependent pathways of tumor angiogenesis may exist. For adequate application of angiogenesis inhibitors in tumor patients, analysis of prevailing angiogenesis pathways may be a prerequisite.     

抑制CXCR4活性对乳腺癌骨转移影响的体内外研究

目的:应用特异性抑制剂AMD3100抑制人乳腺癌骨高转移MDA-MB-231SA-rfp细胞中CXCR4的活性,探讨CX-CR4在乳腺癌细胞体内、外增殖和迁移中的作用和机制。方法:CCK8法和Transwell法检测AMD3100对MDA-MB-231SA-rfp细胞体外增殖和迁移能力的影响。构建MDA-MB-231SA-rfp细胞骨转移裸鼠模型,以不同质量浓度的AMD3100处理后,X线影像观察骨转移情况,进一步利用MicroPET进行半定量分析,并应用H-E染色检测骨转移灶的定位。Western blotting法检测AMD3100对MDA-MB-231SA-rfp细胞和移植瘤转移灶组织中CXCR4蛋白表达的影响。结果:AMD3100能明显抑制MDA-MB-231SA-rfp细胞在SDF-1刺激下的增殖和迁移(P<0.05),较高质量浓度(2 000 ng/ml)的AMD3100效果更明显(P<0.01)。成功构建MDA-MB-231SA-rfp细胞裸鼠乳腺癌转移模型,不同质量浓度AMD3100处理后,小鼠下肢骨骨质破坏程度降低;MicroPET分析发现,对照组、低剂量AMD3100组、高剂量AMD3100组SUVmax值分别为9.44±0.53、5.70±0.25、2.18±0.47(P<0.01);组织病理检测证实为乳腺癌骨转移灶。Western blotting结果显示,AMD3100作用前后MDA-MB-231SA-rfp细胞和骨转移灶标本中CXCR4蛋白表达无明显变化。结论:AMD3100降低CXCR4的活性能抑制乳腺癌MDA-MB-231SA-rfp细胞体外增殖和迁移能力,并能抑制裸鼠体内乳腺癌骨转移灶的形成。     

肿瘤微环境中CXC型趋化因子及其受体的研究进展

趋化因子是一种可以由肿瘤细胞和基质细胞产生的小分子分泌蛋白,趋化因子受体在肿瘤细胞和基质细胞表面也均有表达,趋化因子和其相配对的同源受体结合通过直接和间接方式调控肿瘤生长,包括激活信号通路直接调控肿瘤细胞的增殖与转移、作用于血管内皮细胞间接调控肿瘤及协调免疫细胞在组织内的迁移和定位后影响免疫反应调控肿瘤。趋化因子分为CXC、CC、CX3C及C四大类,研究较多的亚型为CXC和CC。鉴于CXC趋化因子及其受体在恶性肿瘤中作用广泛,且与免疫系统关系密切,有望成为一个有潜力的治疗靶标,其与免疫检查点抑制剂联合作用于肿瘤微环境（tumor microenvironment,TME）,改善肿瘤免疫反应。本文对CXC亚型的趋化因子/趋化因子受体轴研究进展进行综述,包括促肿瘤轴CXCR2/CXCLs、CXCR4/CXCL12 和抑肿瘤轴CXCR3/CXCL9~11 的基本生物学特性、对肿瘤的直接作用、对TME的间接作用、靶向治疗以及这3 个轴所包含的受体及配体的预测预后意义。     

Expression pattern of CXC chemokine receptor-4 is correlated with lymph node metastasis in human invasive ductal carcinoma

Background

The stromal cell-derived factor-1/CXC chemokine receptor-4 (SDF-1/CXCR4) signal has been shown to be important in various immunological reactions. Recent studies have suggested that CXCR4 is expressed in certain cancer cells and that they use this chemokine receptor efficiently for metastasis formation.

Method

The expression of CXCR4 was evaluated by immunohistochemical study in 79 surgically resected invasive ductal carcinomas, and the relation between the staining pattern and clinicopathological features was examined.

Results

CXCR4 was diffusely and homogeneously expressed in 59 cancers, which were further divided into 28 high-expression and 31 low-expression cancers by their staining intensity. The other 20 cancers showed heterogeneous immunoreactivity in tumor tissue, which was defined as focal type. In comparison with the diffuse type, focal type tumors showed significantly more extensive lymph node metastasis, because the number and extent of metastatic nodes were larger in the focal than the diffuse type. In the diffuse type, the rate of node-positive cases did not show a difference in staining intensity. However, high-CXCR4 tumors showed more extensive nodal metastasis in comparison with low-expression tumors. In contrast, the expression pattern of CXCR4 did not have a significant correlation with hematogeneous metastasis. The overall survival of these patients tended to be better in the diffuse type than in the focal type, although the difference was not statistically significant.

Conclusion

The expression pattern of CXCR4 was significantly correlated with the degree of lymph node metastasis in breast cancers. Our data suggest that CXCR4 might be particularly important in facilitating metastasis through the lymphatic system.     

Autocrine tumor growth regulation and tumor-associated hypoglycemia in murine melanoma B16 in vivo

A substance immunochemically cross-reactive with insulin (SICRI) appears in melanoma B16 growing in diabetic and nondiabetic C57BL/6 mice. Progression of tumor size is paralleled by the increase of SICRI levels in the serum of both diabetic and nondiabetic animals; this increase correlates with a decreased concentration of circulating glucose and an elevated concentration of growth hormone in blood. Melanoma B16 grown under serum-free culture conditions secretes SICRI into the medium. Affinity-purified SICRI stimulates glucose uptake by rat epididymal adipocytes and competes with radiolabeled insulin for binding to these cells. Low concentrations of SICRI enhance growth of cultured melanoma B16 cells, whereas high concentrations of this substance have inhibitory growth effects on these cells. Porcine insulin, human insulin-like growth factors I and II, human growth hormone, platelet-derived growth factor, epidermal growth factor, and fibroblast growth factor have negligible influence on growth of melanoma B16.     

The chemokine receptor CCR4 promotes tumor growth and lung metastasis in breast cancer

Increasing evidence has shown that chemokines and chemokine receptors are associated with tumor growth and metastasis. CCR4, an important chemokine receptor for regulating immune homeostasis, is thought to be involved in hematologic malignancies and has also recently implicated in some solid tumors, such as gastric cancer. The possible role of CCR4 in breast cancer has not been well elucidated. In this study, we show that CCR4 is differentially expressed in human breast cancer cell lines. Specifically, we find that CCR4 is overexpressed in breast cancer cell lines with high metastatic potential. More importantly, we used a combination of overexpression and RNA interference to demonstrate that CCR4 promotes breast tumor growth and lung metastasis in mice. Furthermore, we find that microvessel density is significantly increased in tumors formed by CCR4-overexpressing cells and decreased in those formed by CCR4-knockdown cells. We find that overexpression of CCR4 can enhance the chemotactic response of breast cancer cells to CCL17. However, the expression of CCR4 does not affect the proliferation of breast cancer cells in vitro. Furthermore, we show that CCR4 expression is positively correlated with HER2 expression, tumor recurrence and lymph node, lung and bone metastasis (P < 0.05). Multivariate analysis showed that CCR4 expression is a significant independent prognostic factor for overall survival (P = 0.036) but not for disease-free survival in patients with breast cancer (P = 0.071). Survival analysis indicated a strong association between CCR4 expression and lower overall survival (P = 0.0001) and disease-free survival (P = 0.016) in breast cancer.     

Hypoxia-induced CXC chemokine ligand 14 expression drives protumorigenic effects through activation of insulin-like growth factor-1 receptor signaling in glioblastoma

Hypoxic tumor microenvironment (HTM) promotes a more aggressive and malignant state in glioblastoma. However, little is known about the role and mechanism of CXC chemokine ligand 14 (CXCL14) in HTM-mediated glioblastoma progression. In this study, we report that CXCL14 expression correlated with poor outcomes, tumor grade, and hypoxia-inducible factor (HIF) expression in patients with glioblastoma. CXCL14 was upregulated in tumor cells within the hypoxic areas of glioblastoma. Hypoxia induced HIF-dependent expression of CXCL14, which promoted glioblastoma tumorigenicity and invasiveness in vitro and in vivo. Moreover, CXCL14 gain-of-function in glioblastoma cells activated insulin-like growth factor-1 receptor (IGF-1R) signal transduction to regulate the growth, invasiveness, and neurosphere formation of glioblastoma. Finally, systemic delivery of CXCL14 siRNA nanoparticles (NPs) with polysorbate 80 coating significantly suppressed tumor growth in vivo and extended the survival time in patient-derived glioblastoma xenografts. Together, these findings suggest that HIF-dependent CXCL14 expression contributes to HTM-promoted glioblastoma tumorigenicity and invasiveness through activation of the IGF-1R signaling pathway. CXCL14 siRNA NPs as an oligonucleotide drug can inhibit glioblastoma progression and constitute a translational path for the clinical treatment of glioblastoma patients.     

The roles of chemokine CXCL12 in embryonic and brain tumor angiogenesis

The formation of blood vessels in embryos and tumors are different processes but under the control of common molecular mechanisms. Chemokine CXCL12 involved in both embryonic and tumor angiogenesis. In this review, we summarize recent advances in understanding the roles of CXCL12 in brain tumor angiogenesis/vasculogenesis. CXCL12 and its cognate receptors are abnormally induced in brain tumors, in particular in tumor cells and endothelium. Pathologically enhanced CXCL12 signaling may promote the formation of new vessels through recruiting circulating endothelial progenitor cells or directly enhancing the migration/growth of endothelial cells. Therefore, CXCL12 signaling represents an important mechanism that regulates brain tumor angiogenesis/vasculogenesis and may provide potential targets for anti-angiogenic therapy in malignant gliomas.