IL-8 reduced tumorigenicity of human ovarian cancer in vivo due to neutrophil infiltration

Paclitaxel is a frontline therapy for ovarian cancer. Our laboratory has shown that paclitaxel induces IL-8, a member of the C-X-C family of chemokines, in subsets of human ovarian cancer cells. However, the critical issue concerns the biological significance of this chemokine in human ovarian cancer. To study the influence of IL-8 on tumor growth, human ovarian cancer cell lines were transfected with an expression vector for human IL-8 and tested for their ability to form tumors in nude mice. IL-8 expression by the transfected cells did not alter their growth properties in vitro. In contrast, tumor growth in vivo was significantly attenuated in animals receiving IL-8-expressing cells when compared with mice injected with control cells. As additional evidence that IL-8 is a crucial factor in tumor growth, it was noted that ovarian cell lines in which constitutive IL-8 expression is elevated did not form tumors. Injection of neutralizing Ab to IL-8 reverted the phenotype and caused tumor growth in vivo. Examination of tissue from the inoculation site revealed a dramatically elevated cellularity, containing neutrophils and macrophages, in mice receiving IL-8-expressing tumor cells. These results suggest that IL-8 production by human ovarian tumor cells can play a role in reducing the rate of tumor growth; this effect may be mediated by the increased targeting of neutrophil and other mononuclear cells to the tumor injection site. These studies indicate a role for IL-8 in ovarian cancer control and suggest that chemotherapy-induced IL-8 may have a positive role in controlling tumor growth.     

Effect of interleukin-8 on production of tumor-associated substances and autocrine growth of human liver and pancreatic cancer cells

We have previously reported that human liver cancer cell lines produce interleukin-8 (IL-8) at high levels. Those tumor cells appeared to express two kinds of IL-8 receptor on their surface. In order to analyze the role of IL-8 on the biological characteristics of those tumor cells, we suppressed IL-8 production from human liver (HuH-7 and HuCC-T1) and pancreatic cancer cell lines (HuP-T4) by treatment with IL-8 antisense oligonucleotides. Suppression of IL-8 production resulted not only in inhibition of cell growth, but also in an increase in the concentrations of some tumor-associated substances such as carbohydrate antigen 19-9 (CA19-9) in the medium. These data indicate that IL-8 produced by human liver and pancreatic tumors may act as an autocrine growth factor and may control the production of some tumor-associated substances. Furthermore, surface expression of sialyl-Lewis^a, which is a ligand for ELAM-1 on human umbilical vein endothelial cells (HUVEC), HuCC-T1 and HuP-T4 cells was decreased and the attachment of these tumor cells to HUVEC was inhibited by treatment with IL-8 antisense oligonucleotide. Since the soluble form of CA19-9 (sialyl-Lewis^a) was shown to inhibit the tumor cell binding to HUVEC, the decrease in release of CA19-9 into the medium and increase in the expression of sialyl-Lewis^a on the cell surface may suggest that IL-8 production from the tumor cells enhances metastatic potential by augmenting the binding activity of the tumor cells to HUVEC. These data demonstrate that a cytokine produced by tumor cells may function as an autocrine growth factor and affect tumor cell dissemination. Received: 4 February 1998 / Accepted: 6 May 1998     

Integrin αvβ6 Promotes Lung Cancer Proliferation and Metastasis through Upregulation of IL-8–Mediated MAPK/ERK Signaling

Lung cancer is notorious for high morbidity and mortality around the world. Interleukin (IL)-8, a proinflammatory chemokine with tumorigenic and proangiogenic effects, promotes lung cancer cells growth and migration and contributes to cell aggressive phenotypes. Integrin αvβ6 is a receptor of transmembrane heterodimeric cell surface adhesion, and its overexpression correlates with poor survival from non–small cell lung cancer. However, the cross talk between αvβ6 and IL-8 in lung cancer has not been characterized so far. Herein, human lung cancer samples were analyzed, and it revealed that the immunohistochemical and mRNA expression of integrin αvβ6 was significantly correlated with the expression of IL-8. Furthermore, in vitro, integrin αvβ6 increased cell proliferation, migration, and invasion by impairing the expressions of MMP-2 and MMP-9 and inhibited cell apoptosis in human lung cancer cells A549 and H460. In addition, integrin αvβ6 upregulated IL-8 expression through activating MAPK/ERK signaling. The in vivo experiment showed that integrin αvβ6 promoted tumor growth in xenograft model mice by accelerating tumor volume and reducing apoptosis. Meanwhile, lung metastasis model experiment suggested that integrin αvβ6 stimulated tumor metastasis with the increase of lung/total weight and tumor nodules. Simultaneously, integrin αvβ6 upregulated IL-8 expression detected by both Western blots and immunohistochemistry, along with the activation of MAPK/ERK signaling. Overall, these data suggested that, in vitro and in vivo, integrin αvβ6 promoted lung cancer proliferation and metastasis, at least in part, through upregulation of IL-8–mediated MAPK/ERK signaling. Thus, the inhibition of integrin αvβ6 and IL-8 may be the key for the treatment of lung cancer.     

Pancreatic cancer growth promoted by bone marrow mesenchymal stromal cell–derived IL-6 is reversed predominantly by IL-6 blockade

Pancreatic cancer is a highly lethal cancer characterized by local invasiveness, early metastasis, recurrence and high resistance to current therapies. Extensive stroma or desmoplasia is a key histological feature of the disease, and interactions between cancer and stromal cells are critical for pancreatic cancer development and progression. Mesenchymal stromal cells [MSCs] exhibit preferential tropism to primary and metastatic tumor sites and may either suppress or support tumor growth. Although MSCs represent a potential source of pancreatic cancer stroma, their contribution to pancreatic tumor growth remains poorly known. Here, we show that bone marrow MSCs significantly contribute to pancreatic cancer growth in vitro and in vivo. Furthermore, MSCs create a pro-carcinogenic microenvironment through the release of key factors mediating growth and angiogenesis, including interleukin (IL)-6, IL-8, vascular endothelial growth factor and activation of STAT3 signaling in tumor cells. IL-6 released by MSCs was largely responsible for the pro-tumorigenic effects of MSCs. Knockdown of IL-6 expression in MSCs by small interfering RNA (siRNA) abolished the MSC growth-promoting effect in vitro, reducing tumor cell proliferation and clonogenic potential. In addition, in a heterotopic nude mouse model of human pancreatic tumor xenografts, blockade of IL-6 with the anti-IL-6 receptor antibody, tocilizumab, or of its downstream effector STAT3 with the small molecule STAT3 inhibitor S3I-201, abrogated MSC-mediated tumor promotion and delayed tumor formation significantly. Our data demonstrate that MSCs promote pancreatic cancer growth, with IL-6 produced by MSCs playing a pivotal role.     

IL-8与胃癌关系的研究进展

IL-8是趋化性细胞因子,可以促进炎症细胞趋化和诱导细胞增殖,在胃癌组织中高表达。影响IL-8在胃癌组织中表达水平的因素包括幽门螺杆菌感染、NF-κB的干预、IL-8的基因多态性、表皮生长因子（EGF）的水平。IL-8主要参与胃癌的血管形成、促进金属蛋白酶的表达、影响E-cad和ICAM-1的水平、促进细胞有丝分裂、促使肿瘤转移等,对胃癌的发生、发展、预后均起重要的作用。选择性阻断IL-8及其受体具有抑癌作用,有望成为胃癌治疗的基础药物之一。     

Toll-Like Receptor 4 Prompts Human Breast Cancer Cells Invasiveness via Lipopolysaccharide Stimulation and Is Overexpressed in Patients with Lymph Node Metastasis

Toll-like receptor (TLR)4-mediated signaling has been implicated in tumor cell invasion, survival, and metastasis in a variety of cancers. This study investigated the expression and biological role of TLR4 in human breast cancer metastasis. MCF-7 and MDA-MB-231 are human breast cancer cell lines with low and high metastatic potential, respectively. Using lipopolysaccharide (LPS) to stimulate MCF-7 and MDA-MB-231 cells, expression of TLR4 mRNA and protein increased compared with that in control cells. TLR4 activation notably up-regulated expression of matrix metalloproteinase (MMP)-2, MMP-9 and vascular endothelial growth factor(VEGF) mRNA and their secretion in the supernatants of both cell lines. LPS enhanced invasion of MDA-MB-231 cells by transwell assay and MCF-7 cells by wound healing assay. LPS triggered increased expression of TLR4 downstream signaling pathway protein myeloid differentiation factor 88(MyD88) and resulted in interleukin (IL)-6 and IL-10 higher production by human breast cancer cells. Stimulation of TLR4 with LPS promoted tumorigenesis and formed metastatic lesions in liver of nude mice. Moreover, expression of TLR4 and MyD88 as well as invasiveness and migration of the cells could be blocked by TLR4 antagonist. Combined with clinicopathological parameters, TLR4 was overexpressed in human breast cancer tissue and correlated with lymph node metastasis. These findings indicated that TLR4 may participate in the progression and metastasis of human breast cancer and provide a new therapeutic target.     

IL-10 promotes resistance to apoptosis and metastatic potential in lung tumor cell lines

Treatment of non-small cell lung carcinoma (NSCLC) remains at a disappointingly low success rate. Not only is metastatic spread common in NSCLC, but therapeutic success decreases dramatically once metastases are present. Understanding factors which contribute to poor prognosis in NSCLC is critical for development of more successful therapeutic approaches. Interleukin-10 (IL-10) expression has been shown in several studies to correlate with a poorer prognosis in NSCLC; however, the mechanisms by which IL-10 affects lung tumor growth and metastases are unclear. The goal of this study was to evaluate the effects of tumor-derived IL-10 on the growth and metastasis of lung cancer cells in a murine model. Lewis lung carcinoma cells were stably transfected with the chicken ovalbumin gene (cOVA) as a model tumor antigen (LL43 tumor cells) and subsequently transfected with the murine IL-10 gene (LL43-10 tumor cells). Subcutaneous growth of the LL43 tumor cells was not affected by expression of IL-10. However, LL43-10 tumors had a fourfold increase in tumor microvessel density, as indicated by CD31 staining. Metastatic potential was also increased in IL-10-expressing lung tumor cells, leading to a greater number of tumor cells in lymph nodes draining the primary tumor site. Finally, exposure of Lewis lung tumor cells in vitro to exogenous IL-10 dramatically increased their resistance to UV-induced apoptosis. These results indicate that a primary effect of IL-10 on lung cancer cells may be to increase their metastatic potential by promoting angiogenesis and resistance to apoptosis.     

The role of the EGFR signaling in tumor microenvironment

The epidermal growth factor receptor (EGFR) family comprehends four different tyrosine kinases (EGFR, ErbB-2, ErbB-3, and ErbB-4) that are activated following binding to epidermal growth factor (EGF)-like growth factors. It has been long established that the EGFR system is involved in tumorigenesis. These proteins are frequently expressed in human carcinomas and support proliferation and survival of cancer cells. However, activation of the EGFR in non-malignant cell populations of the neoplastic microenvironment might also play an important role in cancer progression. EGFR signaling regulates in tumor cells the synthesis and secretion of several different angiogenic growth factors, including vascular endothelial growth factor (VEGF), interleukin-8 (IL-8), and basic fibroblast growth factor (bFGF). Overexpression of ErbB-2 also leads to increased expression of angiogenic growth factors, whereas treatment with anti-EGFR or anti-ErbB-2 agents produces a significant reduction of the synthesis of these proteins by cancer cells. EGFR expression and function in tumor-associated endothelial cells has also been described. Therefore, EGFR signaling might regulate angiogenesis both directly and indirectly. In addition, activation of EGFR is involved in the pathogenesis of bone metastases. Within the bone marrow microenvironment, cancer cells stimulate the synthesis of osteoclastogenic factors by residing stromal cells, a phenomenon that leads to bone destruction. It has been shown that EGFR signaling regulates the ability of bone marrow stromal cells to produce osteoclastogenic factors and to sustain osteoclast activation. Taken together, these findings suggest that the EGFR system is an important mediator, within the tumor microenvironment, of autocrine and paracrine circuits that result in enhanced tumor growth.     

IL-8通过激活PKC/ERK信号通路促进肾癌细胞上皮细胞-间质细胞转化

上皮细胞-间质细胞转化(EMT)在肿瘤转移方面起着非常重要的作用．肾癌发生EMT的具体分子机制尚不清楚．IL-8是一个重要的炎症趋化因子,研究表明肾癌细胞可以分泌IL-8,但IL-8是否参与肾癌细胞EMT的调节目前尚无报道．我们研究发现,IL-8可以促进肾癌细胞形态发生间质化改变,IL-8刺激后E-钙黏蛋白表达水平下降, N-钙黏蛋白表达上调．另外,IL-8可以促进肾癌细胞侵袭,但对肾癌细胞增殖的影响并不明显．进一步研究显示,IL-8通过激活蛋白激酶C(PKC)引起细胞外调节性激酶(ERK)磷酸化．因此,我们认为IL-8可能通过PKC/ERK信号通路促进肾癌细胞发生EMT,这可能是肾癌转移的重要机制之一．     

Interleukin-8 secretion by ovarian cancer cells increases anchorage-independent growth, proliferation, angiogenic potential, adhesion and invasion

It has been shown that IL-8 is elevated in ovarian cyst fluid, ascites, serum, and tumor tissue from ovarian cancer (OVCA) patients, and increased IL-8 expression correlates with poor prognosis and survival. However, the exact role that IL-8 plays in this malignancy or whether IL-8 can regulate malignant behavior has not been established. Here we demonstrate that overexpression of IL-8 in non-IL-8-expressing A2780 cells (by transfecting with plasmid encoding for sense IL-8) increases anchorage-independent growth, proliferation, angiogenic potential, adhesion and invasion while depletion of endogenous IL-8 expression in IL-8-overexpressing SKOV-3 cells (by transfecting with plasmid encoding for antisense IL-8) decreases the above effects. Further investigation indicates that IL-8-stimulated cell proliferation correlates with alteration of cell cycle distribution by increasing levels of cell cycle-regulated Cyclin D1 and Cyclin B1 proteins as well as activation of PI3K/Akt and Raf/MEK/ERK, whereas IL-8-enhanced OVCA cell invasive correlates with increased MMP-2 and MMP-9 activity and expression. Our data suggest that IL-8 secreted by OVCA cells promotes malignant behavior of these cells via inducing intracellular molecular signaling. Therefore, modulation of IL-8 expression or its related signaling pathway may be a promising strategy for controlling the progression and metastasis of OVCA.     

失巢凋亡及其在肿瘤侵袭、转移中的调控

作为肿瘤转移的屏障, 细胞与邻近细胞或者细胞外基质(Extracellular matrix, ECM)失去联系后将遭受凋亡, 这种细胞死亡方式称为“失巢凋亡”。正常上皮细胞或不具备转移性质的实体瘤细胞从原位脱落进入血液循环后就会引发失巢凋亡, 失巢凋亡的意义在于防止这些脱落的细胞种植并生长于其他不适宜的地方。而肿瘤细胞, 尤其是一些容易发生远距离转移的恶性肿瘤细胞, 具有极强的抗失巢凋亡特性, 便于转移侵袭。研究发现肿瘤细胞能通过多种方式抵抗失巢凋亡, 比如细胞自分泌生长因子或者由邻近细胞旁分泌, 激活促存活信号通路; 细胞改变整合蛋白的表达模式, 使之能够接收新环境的生存信号; 活性氧(Reactive oxygen species, ROS)通过不依赖配体的方式激活生长因子受体, 从而逃逸凋亡; 上皮间质转化(Epithelial-mesenchymal transition, EMT)激活等。这些方式导致细胞存活信号激活和凋亡途径抑制, 最终使肿瘤细胞抗失巢凋亡, 促进转移。文章综述了当前研究的肿瘤转移的关键机制, 这些策略也将成为肿瘤治疗的重要靶点。     

Elevation of circulating interleukin-8 is related to lymph node and distant metastases in esophageal squamous cell carcinomas--implication for clinical evaluation of cancer patient

The presence of lymph node metastasis (LNM) is an important factor in clinical evaluation of esophageal cancer patients. Biological markers able to support detection of metastatic lymph nodes are sought after. Interleukin-8 (IL-8) is overexpressed by many cancers and involved in cancer dissemination. We investigated the relationship between circulating IL-8 and clinicopathological features of esophageal squamous cell carcinoma (ESCC), and evaluated the diagnostic potential of IL-8, with reference to the key angiogenic and lymphangiogenic factors: vascular endothelial growth factors A and C (VEGF-A and VEGF-C). We found elevated IL-8 levels in ESCC patients, correlated with tumor size and cancer dissemination, especially LNM. Circulating IL-8 correlated with lymphangiogenic VEGF-C rather then angiogenic VEGF-A. The association weakened in metastatic cancers, suggesting divergent mechanism of IL-8 involvement in the dissemination process. The cytokine levels correlated with platelets and neutrophils, pointing at these cells as possible sources of circulating IL-8. We demonstrated IL-8 that positively correlated with inflammation status of ESCC patients. Circulating IL-8 was a better indicator of ESCC dissemination than VEGF-A or VEGF-C. Yet, the detection rates were not satisfactory enough to allow for the recommendation of IL-8 determination as an adjunct to the clinical evaluation of lymph node involvement in ESCC patients.     

IL-8 expression in malignant melanoma: implications in growth and metastasis

This review article has described briefly studies supporting the concept that IL-8 expression and its regulation by inflammatory cytokines like IL-1 may play an important role in controlling the phenotypes associated with melanoma progression and metastasis. It is clear from the experiments presented here that IL-8 is an important autocrine multifunctional cytokine that modulates melanoma/cell proliferation, migration by induction of extracellular matrix degradation enzymes and induces neovascularization, all of which are critical for melanoma growth and metastasis. In addition, their expression in melanoma tumor specimens suggests an association between IL-8 expression and tumor aggressiveness. Further, inflammatory cytokines produced by either tumor cells or stromal cells may regulate IL-8 expression, which can control melanoma growth and enhance our current knowledge regarding melanoma progression and metastasis. Understanding these events and their significance will allow us to design novel therapeutic approaches for treatment of melanoma.