Significance of interleukin-6 (IL-6) in breast cancer (review)

Aberrant subcellular immunolocalization of NOTCH-1 activated intracellular domain in feline mammary tumours

NOTCH-1 is a transmembrane receptor protein. Ligand proteins expressed on the surface of neighbouring cells bind to the NOTCH-1 extracellular domain by juxtacrine signalling and release the NOTCH intracellular domain (NICD) to alter gene expression. Forty feline mammary lesions (34 malignant and six hyperplastic) were submitted for immunohistochemical analysis of NICD expression using an anti-feline NICD monoclonal antibody. Associations between NICD expression in carcinomas and morphological parameters, as well as overall survival (OS), were investigated. NICD nuclear expression was observed in hyperplastic lesions (100%) while cytoplasmic localization was evident in carcinomas (0% nuclear positive; 87.5% cytoplasmic positive; 12.5% negative). Cytoplasmic NICD localization was statistically associated with carcinomas, while nuclear labelling was associated with hyperplasia. No significant correlation between positive or negative NICD expression and OS or morphological parameters was detected. NOTCH-1 activation, immunohistochemically identified by the NICD active form, appears to play a role in feline mammary carcinoma biology as the majority of tumours express this protein. Nuclear localization is consistent with the established NICD metabolic intranuclear pathway while cytoplasmic accumulation suggests aberrant NOTCH-1 signalling typical of malignant tumour progression.

Regulation of angiogenesis via Notch signaling in breast cancer and cancer stem cells

Breast cancer angiogenesis is elicited and regulated by a number of factors including the Notch signaling. Notch receptors and ligands are expressed in breast cancer cells as well as in the stromal compartment and have been implicated in carcinogenesis. Signals exchanged between neighboring cells through the Notch pathway can amplify and consolidate molecular differences, which eventually dictate cell fates. Notch signaling and its crosstalk with many signaling pathways play an important role in breast cancer cell growth, migration, invasion, metastasis and angiogenesis, as well as cancer stem cell (CSC) self-renewal. Therefore, significant attention has been paid in recent years toward the development of clinically useful antagonists of Notch signaling. Better understanding of the structure, function and regulation of Notch intracellular signaling pathways, as well as its complex crosstalk with other oncogenic signals in breast cancer cells will be essential to ensure rational design and application of new combinatory therapeutic strategies. Novel opportunities have emerged from the discovery of Notch crosstalk with inflammatory and angiogenic cytokines and their links to CSCs. Combinatory treatments with drugs designed to prevent Notch oncogenic signal crosstalk may be advantageous over λ secretase inhibitors (GSIs) alone. In this review, we focus on the more recent advancements in our knowledge of aberrant Notch signaling contributing to breast cancer angiogenesis, as well as its crosstalk with other factors contributing to angiogenesis and CSCs.

The immune system in the pathogenesis of ovarian cancer

Clinical outcomes in ovarian cancer are heterogeneous even when considering common features such as stage, response to therapy, and grade. This disparity in outcomes warrants further exploration into tumor and host characteristics. One compelling host characteristic is the immune response to ovarian cancer. While several studies have confirmed a prominent role for the immune system in modifying the clinical course of the disease, recent genetic and protein analyses also suggest a role in disease incidence. Recent studies also show that anti-tumor immunity is often negated by immune suppressive cells present in the tumor microenvironment. These suppressive immune cells also directly enhance the pathogenesis through the release of various cytokines and chemokines, which together form an integrated pathologic network. Thus, future research into immunotherapy targeting ovarian cancer will likely become increasingly focused on combination approaches that simultaneously augment immunity while preventing local immune suppression or by disrupting critical cytokine networks.

Adipose tissue immunity and cancer

Inflammation and altered immune response are important components of obesity and contribute greatly to the promotion of obesity-related metabolic complications, especially cancer development. Adipose tissue expansion is associated with increased infiltration of various types of immune cells from both the innate and adaptive immune systems. Thus, adipocytes and infiltrating immune cells secrete pro-inflammatory adipokines and cytokines providing a microenvironment favorable for tumor growth. Accumulation of B and T cells in adipose tissue precedes macrophage infiltration causing a chronic low-grade inflammation. Phenotypic switching toward M1 macrophages and Th1 T cells constitutes an important mechanism described in the obese state correlating with increased tumor growth risk. Other possible synergic mechanisms causing a dysfunctional adipose tissue include fatty acid-induced inflammation, oxidative stress, endoplasmic reticulum stress, and hypoxia. Recent investigations have started to unravel the intricacy of the cross-talk between tumor cell/immune cell/adipocyte. In this sense, future therapies should take into account the combination of anti-inflammatory approaches that target the tumor microenvironment with more sophisticated and selective anti-tumoral drugs.

Lack of knowledge: breast cancer and the soluble interleukin-6 receptor

BACKGROUND

Cytokines are and may be used as therapeutic targets in cancer therapy. In breast cancer, interleukin (IL)-6 is associated with different features of tumor biology like metastasis, certain stages, and decreased survival. It is now an established fact that signaling via the soluble IL-6 receptor (sIL-6R) («transsignaling») is an important process in the IL-6 machinery.

METHODS AND RESULTS

In this mini-review, we discover that published knowledge about sIL-6R serum levels in breast cancer patients is sparse and, furthermore, most in vitro data merely show that tumor cells produce the sIL-6R endogenously.

CONCLUSIONS

Therefore, a lot of research is still necessary to analyze the significance of the sIL-6R and therefore the transsignaling process in breast tumors. More knowledge about the sIL-6R in breast cancer would give insights into its putative role as blood marker of active tumor disease. Secondly, the sIL-6R may be useful in breast cancer as a new therapeutic pathway. If, as suggested by the literature, IL-6 mediates the aggressiveness and the growth of breast tumors, elevated circulating levels of IL-6 and its receptor may identify patients for whom the IL-6 complex is a therapeutic target.

Chemoresistance and Cancer-Related Inflammation: Two Hallmarks of Cancer Connected by an Atypical Link, PKCζ

Atypical protein kinase C isoforms are serine threonine kinases involved in various pathological conditions. In recent years, the PKCζ isoform has emerged as an important regulator of multiple cellular processes operating in cancer. In this review, we will focus on the PKCζ isoform as an oxidative-sensing kinase involved in cancer-related inflammation and chemoresistance. We will discuss its nuclear localization and its possible pivotal role in connecting inflammation with drug resistance.

Interleukin 6 gene polymorphism -174 is associated with the diffuse type gastric carcinoma

The aim of this study was to assess the significance of the interleukin 6 gene polymorphism -174 in gastric cancer risk. The interleukin 6 -174 G/C (rs1800795) gene polymorphisms was analyzed in gastric cancer, peptic ulcer, and nonulcer dyspepsia patients and in healthy control subjects and the data were correlated with the histopathological features of the patients' biopsies. The interleukin 6 -174 GG and GC genotypes have been previously associated with high interleukin 6 serum levels. We discovered that the interleukin 6 -174 GG and GC genotypes are associated with an increased risk of the diffuse histologic subtype of gastric carcinomas (OR: 6.809, P = 0.034), but absent in the intestinal type carcinomas (OR: 1.109, P = 0.908). No significant associations with peptic ulcer, gastric atrophy, or intestinal metaplasia were seen. Our results demonstrate that the interleukin 6 -174 GG and GC genotypes increase the risk of the diffuse type gastric carcinoma, but not the intestinal type gastric carcinoma or its precursor conditions, including atrophy or intestinal metaplasia. Thus, interleukin 6 seems to be an important carcinogenetic factor in the diffuse type gastric adenocarcinoma and its carcinogenetic effect could be noninflammatory.

The anti-cancer property of proteins extracted from Gynura procumbens (Lour.) Merr

Gynura procumbens (Lour.) Merr. belongs to the Asteraceae Family. The plant is a well-known traditional herb in South East Asia and it is widely used to treat inflammation, kidney discomfort, high cholesterol level, diabetic, cancer and high blood pressure. Our earlier study showed the presence of valuable plant defense proteins, such as peroxidase, thaumatin-like proteins and miraculin in the leaf of G. procumbens. However, the effects of these defense proteins on cancers have never been determined previously. In the present study, we investigated the bioactivity of gel filtration fractionated proteins of G. procumbens leaf extract. The active protein fraction, SN-F11/12, was found to inhibit the growth of a breast cancer cell line, MDA-MB-231, at an EC50 value of 3.8 µg/mL. The mRNA expressions of proliferation markers, Ki67 and PCNA, were reduced significantly in the MDA-MB-23 cells treated with SN-F11/12. The expression of invasion marker, CCL2, was also found reduced in the treated MDA-MB-231 cells. All these findings highlight the anti-cancer property of SN-F11/12, therefore, the proteins in this fraction can be a potential chemotherapeutic agent for breast cancer treatment.

Inflammation and breast cancer

SUMMARY The relationship between breast cancer (BC) and inflammation remains unclear. Some risk factors, such as age, obesity and postmenopausal status, are also associated with increased levels of circulating proinflammatory cytokines and systemic inflammation. The role of T lymphocytes during BC development has been the subject of great debate, with improved survival reported when CD8+ and CD3+ T-lymphocytic infiltrates are present. Studies of B-lymphocytic infiltrates and prognosis have yielded conflicting results, but the extent of infiltration of tumor-associated macrophages is associated with reduced relapse-free and overall survival. There is consistent evidence that increased levels of proinflammatory factors, such as IL-6, IL-1β and TNF-α, and inflammatory chemokines, such as CCL2 and CCL5, are associated with increased risk of BC and poorer prognosis. However, it is not known whether this actually plays a role in tumor development. Substantially more work is needed to achieve a basis for effective anticancer therapy.

Bone Morphogenetic Proteins stimulate mammary fibroblasts to promote mammary carcinoma cell invasion

Bone Morphogenetic Proteins (BMPs) are secreted cytokines that are part of the Transforming Growth Factor β (TGFβ) superfamily. BMPs have been shown to be highly expressed in human breast cancers, and loss of BMP signaling in mammary carcinomas has been shown to accelerate metastases. Interestingly, other work has indicated that stimulation of dermal fibroblasts with BMP can enhance secretion of pro-tumorigenic factors. Furthermore, treatment of carcinoma-associated fibroblasts (CAFs) derived from a mouse prostate carcinoma with BMP4 was shown to stimulate angiogenesis. We sought to determine the effect of BMP treatment on mammary fibroblasts. A large number of secreted pro-inflammatory cytokines and matrix-metallo proteases (MMPs) were found to be upregulated in response to BMP4 treatment. Fibroblasts that were stimulated with BMP4 were found to enhance mammary carcinoma cell invasion, and these effects were inhibited by a BMP receptor kinase antagonist. Treatment with BMP in turn elevated pro-tumorigenic secreted factors such as IL-6 and MMP-3. These experiments demonstrate that BMP may stimulate tumor progression within the tumor microenvironment.

Bone Morphogenetic Proteins stimulate mammary fibroblasts to promote mammary carcinoma cell invasion

Bone Morphogenetic Proteins (BMPs) are secreted cytokines that are part of the Transforming Growth Factor β (TGFβ) superfamily. BMPs have been shown to be highly expressed in human breast cancers, and loss of BMP signaling in mammary carcinomas has been shown to accelerate metastases. Interestingly, other work has indicated that stimulation of dermal fibroblasts with BMP can enhance secretion of pro-tumorigenic factors. Furthermore, treatment of carcinoma-associated fibroblasts (CAFs) derived from a mouse prostate carcinoma with BMP4 was shown to stimulate angiogenesis. We sought to determine the effect of BMP treatment on mammary fibroblasts. A large number of secreted pro-inflammatory cytokines and matrix-metallo proteases (MMPs) were found to be upregulated in response to BMP4 treatment. Fibroblasts that were stimulated with BMP4 were found to enhance mammary carcinoma cell invasion, and these effects were inhibited by a BMP receptor kinase antagonist. Treatment with BMP in turn elevated pro-tumorigenic secreted factors such as IL-6 and MMP-3. These experiments demonstrate that BMP may stimulate tumor progression within the tumor microenvironment.

Inflammatory breast cancer: New factors contribute to disease etiology: A review

Inflammatory breast cancer (IBC) is a highly metastatic and fatal form of breast cancer. In fact, IBC is characterized by specific morphological, phenotypic, and biological properties that distinguish it from non-IBC. The aggressive behavior of IBC being more common among young women and the low survival rate alarmed researchers to explore the disease biology. Despite the basic and translational studies needed to understand IBC disease biology and identify specific biomarkers, studies are limited by few available IBC cell lines, experimental models, and paucity of patient samples. Above all, in the last decade, researchers were able to identify new factors that may play a crucial role in IBC progression. Among identified factors are cytokines, chemokines, growth factors, and proteases. In addition, viral infection was also suggested to participate in the etiology of IBC disease. In this review, we present novel factors suggested by different studies to contribute to the etiology of IBC and the proposed new therapeutic insights.

Variation in inflammatory cytokine/growth-factor genes and mammographic density in premenopausal women aged 50-55

Background

Mammographic density (MD) has been found to be an independent risk factor for breast cancer. Although data from twin studies suggest that MD has a strong genetic component, the exact genes involved remain to be identified. Alterations in stromal composition and the number of epithelial cells are the most predominant histopathological determinants of mammographic density. Interactions between the breast stroma and epithelium are critically important in the maturation and development of the mammary gland and the cross-talk between these cells are mediated by paracrine growth factors and cytokines. The potential impact of genetic variation in growth factors and cytokines on MD is largely unknown.

Methods

We investigated the association between 89 single nucleotide polymorphisms (SNPs) in 7 cytokine/growth-factor genes (FGFR2, IGFBP1, IGFBP3, TGFB1, TNF, VEGF, IL6) and percent MD in 301 premenopausal women (aged 50 to 55 years) participating in the Norwegian Breast Cancer Screening Program. We evaluated the suggestive associations in 216 premenopausal Singapore Chinese Women of the same age.

Results

We found statistically significant associations between 9 tagging SNPs in the IL6 gene and MD in Norwegian women; the effect ranged from 3–5% in MD per variant allele (p-values = 0.02 to 0.0002). One SNP in the IL6 (rs10242595) significantly influenced MD in Singapore Chinese women.

Conclusion

Genetic variations in IL6 may be associated with MD and therefore may be an indicator of breast cancer risk in premenopausal women.

Choice of anesthetic technique on plasma concentrations of interleukins and cell adhesion molecules

BACKGROUND

Whether inflammatory responses to surgery are comparably activated during total intravenous anesthesia (TIVA) and during volatile anesthesia remains unclear. We thus compared the perioperative effects of TIVA and isoflurane anesthesia on plasma concentrations of proinflammatory and anti-inflammatory interleukins and cell adhesion molecules.

METHODS

Patients having laparoscopic cholecystectomies were randomly allocated to two groups: 44 were assigned to TIVA and 44 to isoflurane anesthesia. IL-1β, IL-6, IL-8, IL-10, IL-13, and the cellular adhesion molecules intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 were determined preoperatively, before incision, and at 2 and 24 hours postoperatively. Our primary outcomes were area-under-the-curve cytokine and adhesion molecule concentrations over 24 postoperative hours.

RESULTS

The only statistically significant difference in area-under-the-curve concentrations was for IL-6, which was greater in patients given isoflurane:78 (95% confidence interval (CI): 52 to 109) pg/ml versus 33 (22 to 50) pg/ml, P= 0.006. Two hours after surgery, IL-6 was significantly greater than baseline in patients assigned to isoflurane: 47 (95% CI: 4 to 216, P<0.001) pg/ml versus 18 (95%CI: 4 to 374, P<0.001) pg/ml in the TIVA group. In contrast, IL-10 was significantly greater in patients assigned to TIVA: 20 (95% CI: 2 to 140, P<0.001) pg/ml versus 12 (95% CI: 3 to 126, P<0.001) pg/ml. By 24 hours after surgery, concentrations were generally similar between study groups and similar to baseline values.

CONCLUSION

The only biomarker whose postoperative area-under-the-curve concentrations differed significantly as a function of anesthetic management was IL-6. Two hours after surgery, IL-6 concentrations were significantly greater in patients given isoflurane than TIVA. However, the differences were modest and seem unlikely to prove clinically important. Further studies are needed.

FOXP3 expression in tumor cells and tumor-infiltrating lymphocytes is associated with breast cancer prognosis

The forkhead box protein 3 (FOXP3) transcription factor is highly expressed in tumor cells as well as in regulatory T cells (Tregs). It plays a tumor-enhancing role in Tregs and suppresses carcinogenesis as a potent repressor of several oncogenes. The clinical prognostic value of FOXP3 expression has not yet been elucidated. In this study, immunohistochemistry was used to investigate the prognostic significance of FOXP3 expression in tumor cells and tumor-infiltrating lymphocytes (TILs) in breast cancer patients. Of the 100 tumor specimens obtained from primary invasive breast carcinoma, 63 and 57% were evaluated as FOXP3⁺ tumor cells and as being highly infiltrated by FOXP3⁺ lymphocytes, respectively. Although FOXP3 expression in tumor cells was of no prognostic significance, FOXP3⁺ lymphocytes were significantly associated with poor overall survival (OS) (n=98, log-rank test P=0.008). FOXP3 exhibited a heterogeneous subcellular localization in tumor cells (cytoplasm, 31%; nucleus, 26%; both, 6%) and, although cytoplasmic FOXP3 was associated with poor OS (P= 0.058), nuclear FOXP3 demonstrated a significant association with improved OS (P=0.016). Furthermore, when patients were grouped according to their expression of tumor cytoplasmic FOXP3 and lymphocyte FOXP3, there were notable differences in the Kaplan-Meier curves for OS (P<0.001), with a high infiltration of FOXP3⁺ lymphocytes accompanied by a cytoplasmic FOXP3⁺ tumor being the most detrimental phenotype. These findings indicated that FOXP3 expression in lymphocytes as well as in tumor cells may be a prognostic marker for breast cancer. FOXP3 in tumor cells may have distinct biological activities and prognostic values according to its localization, which may help establish appropriate cancer treatments.

The role of intratumoral and systemic IL-6 in breast cancer

Chronic low-grade inflammation plays an important role in the pathogenesis of several cancer forms including breast cancer. The pleiotropic cytokine IL-6 is a key player in systemic inflammation, regulating both the inflammatory response and tissue metabolism during acute stimulations. Here, we review the associations between IL-6 and breast cancer ranging from in vitro cell culture studies to clinical studies, covering the role of IL-6 in controlling breast cancer cell growth, regulation of cancer stem cell renewal, as well as breast cancer cell migration. Moreover, associations between circulating IL-6 and risk of breast cancer, prognosis for patients with prevalent disease, adverse effects and interventions to control systemic IL-6 levels in patients are discussed. In summary, direct application of IL-6 on breast cancer cells inhibits proliferation in estrogen receptor positive cells, while high circulating IL-6 levels are correlated with a poor prognosis in breast cancer patients. This discrepancy reflects distinct roles of IL-6, with elevated systemic levels being a biomarker for tumor burden, physical inactivity, and impaired metabolism, while local intratumoral IL-6 signaling is important for controlling breast cancer cell growth, metastasis, and self renewal of cancer stem cells.

Biomarkers of residual disease, disseminated tumor cells, and metastases in the MMTV-PyMT breast cancer model

Cancer metastases arise in part from disseminated tumor cells originating from the primary tumor and from residual disease persisting after therapy. The identification of biomarkers on micro-metastases, disseminated tumors, and residual disease may yield novel tools for early detection and treatment of these disease states prior to their development into metastases and recurrent tumors. Here we describe the molecular profiling of disseminated tumor cells in lungs, lung metastases, and residual tumor cells in the MMTV-PyMT breast cancer model. MMTV-PyMT mice were bred with actin-GFP mice, and focal hyperplastic lesions from pubertal MMTV-PyMT;actin-GFP mice were orthotopically transplanted into FVB/n mice to track single tumor foci. Tumor-bearing mice were treated with TAC chemotherapy (docetaxel, doxorubicin, cyclophosphamide), and residual and relapsed tumor cells were sorted and profiled by mRNA microarray analysis. Data analysis revealed enrichment of the Jak/Stat pathway, Notch pathway, and epigenetic regulators in residual tumors. Stat1 was significantly up-regulated in a DNA-damage-resistant population of residual tumor cells, and a pre-existing Stat1 sub-population was identified in untreated tumors. Tumor cells from adenomas, carcinomas, lung disseminated tumor cells, and lung metastases were also sorted from MMTV-PyMT transplant mice and profiled by mRNA microarray. Whereas disseminated tumors cells appeared similar to carcinoma cells at the mRNA level, lung metastases were genotypically very different from disseminated cells and primary tumors. Lung metastases were enriched for a number of chromatin-modifying genes and stem cell-associated genes. Histone analysis of H3K4 and H3K9 suggested that lung metastases had been reprogrammed during malignant progression. These data identify novel biomarkers of residual tumor cells and disseminated tumor cells and implicate pathways that may mediate metastasis formation and tumor relapse after therapy.

Childhood adversity increases vulnerability for behavioral symptoms and immune dysregulation in women with breast cancer

Women respond differentially to the stress-associated with breast cancer diagnosis and treatment, with some women experiencing more intense and/or sustained behavioral symptoms and immune dysregulation than others. Childhood adversity has been identified to produce long-term dysregulation of stress response systems, increasing reactivity to stressors encountered during adulthood. This study determined whether childhood adversity increased vulnerability for more intense and sustained behavioral symptoms (fatigue, perceived stress, and depressive symptoms), poorer quality of life, and greater immune dysregulation in women (N=40) with breast cancer. Evaluation was after breast surgery and through early survivorship. Hierarchical linear modeling was used to examine intra-individual and inter-individual differences with respect to initial status and to the pattern of change (i.e. trajectory) of outcomes. At initial assessment, women exposed to childhood emotional neglect/abuse had greater perceived stress, fatigue, depressive symptoms and poorer quality of life, as well as lower natural killer cell activity (NKCA). Although these outcomes improved over time, women with greater childhood emotional neglect/abuse exhibited worse outcomes through early survivorship. No effect was observed on the pattern of change for these outcomes. In contrast, childhood physical neglect predicted sustained trajectories of greater perceived stress, worse quality of life, and elevated plasma IL-6; with no effect observed at initial assessment. Thus, childhood adversity leaves an enduring imprint, increasing vulnerability for behavioral symptoms, poor quality of life, and elevations in IL-6 in women with breast cancer. Further, childhood adversity predisposes to lower NKCA at a critical time when this immune-effector mechanism is most effective at halting nascent tumor seeding.

Mesenchymal stem cell-derived interleukin-6 and vascular endothelial growth factor promote breast cancer cell migration

Several different cytokines and growth factors secreted by mesenchymal stem cells (MSCs) have been hypothesized to play a role in breast cancer progression. By using a small panel of breast cancer cell lines (MCF-7, T47D, and SK-Br-3 cells), we analyzed the role of interleukin-6 (IL-6) and vascular endothelial growth factor A (VEGF) in the cross-talk between MSCs and breast cancer cells. We performed migration assays in which breast cancer cells were allowed to migrate in response to conditioned medium from MSCs (MSCs-CM), in absence or in presence of the anti-VEGF antibody bevacizumab or an anti-IL-6 antibody, alone or in combination. We found that anti-VEGF and anti-IL-6 antibodies inhibited the migration of breast cancer cells and that the combination had an higher inhibitory effect. We next evaluated the effects of recombinant VEGF and IL-6 proteins on breast cancer cell growth and migration. IL-6 and VEGF had not significant effects on the proliferation of breast carcinoma cells. In contrast, both VEGF and IL-6 significantly increased the ability to migrate of MCF-7, T47D and SK-Br-3 cells, with the combination showing a greater effect as compared with treatment with a single protein. The combination of VEGF and IL-6 produced in breast cancer cells a more significant and more persistent activation of MAPK, AKT, and p38MAPK intracellular signaling pathways. These results suggest that MSC-secreted IL-6 and VEGF may act as paracrine factors to sustain breast cancer cell migration.

Role of prostaglandin receptor EP2 in the regulations of cancer cell proliferation, invasion, and inflammation

Population studies, preclinical, and clinical trials suggest a role for cyclooxygenase-2 (COX-2, PTGS2) in tumor formation and progression. The downstream prostanoid receptor signaling pathways involved in tumorigenesis are poorly understood, although prostaglandin E2 (PGE(2)), a major COX-2 metabolite which is usually upregulated in the involved tissues, presumably plays important roles in tumor biology. Taking advantage of our recently identified novel selective antagonist for the EP2 (PTGER2) subtype of PGE(2) receptor, we demonstrated that EP2 receptor activation could promote prostate cancer cell growth and invasion in vitro, accompanied by upregulation of the tumor-promoting inflammatory cytokines, such as IL-1β and IL-6. Our results suggest the involvement of prostaglandin receptor EP2 in cancer cell proliferation and invasion possibly via its inflammatory actions, and indicate that selective blockade of the PGE(2)-EP2 signaling pathway via small molecule antagonists might represent a novel therapy for tumorigenesis.

Effect of exercise on markers of inflammation in breast cancer survivors: the Yale exercise and survivorship study

Physical activity is associated with improved breast cancer survival, but the underlying mechanisms, possibly including modification of the inflammatory state, are not well understood. We analyzed changes in interleukin (IL)-6, C-reactive protein (CRP), and TNF-α in a randomized controlled trial of exercise in postmenopausal breast cancer survivors. Seventy-five women, recruited through the Yale-New Haven Hospital Tumor Registry, were randomized to either a six-month aerobic exercise intervention or usual care. Correlations were calculated between baseline cytokines, adiposity, and physical activity measures. Generalized linear models were used to assess the effect of exercise on IL-6, CRP, and TNF-α. At baseline, IL-6 and CRP were positively correlated with body fat and body mass index (BMI) and were inversely correlated with daily pedometer steps (P < 0.001). We found no significant effect of exercise on changes in inflammatory marker concentrations between women randomized to exercise versus usual care, though secondary analyses revealed a significant reduction in IL-6 among exercisers who reached 80% of the intervention goal compared with those who did not. Future studies should examine the effect of different types and doses of exercise and weight loss on inflammatory markers in large-scale trials of women diagnosed with breast cancer.

Correlation of levels of IL-6 with tumor burden and receptor status in patients of locally advanced carcinoma breast

Inflammatory pathways have garnered considerable interest in the recent past as an important mediator of the molecular mechanisms leading to carcinogenesis. The present study was conducted to evaluate the correlation of levels of IL-6 with tumor burden and receptor status in patients of locally advanced carcinoma breast. This prospective study was conducted by the collaborative efforts of the departments of Surgery and Biochemistry, Maulana Azad Medical College and associated Lok Nayak Hospital and GB Pant Hospitals, New Delhi. The study population comprised of 30 cases of locally advanced breast carcinoma recruited from the surgical outpatient department. The various parameters that were evaluated include detailed clinico-pathological profile and IL-6 levels. Tissue specimens received after surgeries were examined for the various characteristics indicative of tumor prognosis. Majority of the patients was in the age group of 41-50 years and was postmenopausal. The serum level of IL-6 increased as the disease progressed from T3N1M0 to T4dN2M0 (41.4 ± 31.9 vs. 164.0 ± 31.1 pg/ml respectively). There was significant correlation of IL-6 levels with lymph node involvement, tumor grade, mitotic index and adipose tissue invasion. Emerging molecular markers are being investigated for breast cancer prognosis assessment and prediction of response to chemotherapy including selection of best possible treatment modality. Our study showed that there is progressive increase in IL-6 levels as the stage of disease progresses.

Increased levels of interleukins 8 and 10 as findings of canine inflammatory mammary cancer

Inflammatory mammary cancer (IMC) is a distinct form of mammary cancer that affects dogs and women [in humans, IMC is known as inflammatory breast cancer (IBC)], and is characterized by a sudden onset and an aggressive clinical course. Spontaneous canine IMC shares epidemiologic, histopathological and clinical characteristics with the disease in humans and has been proposed as the best spontaneous animal model for studying IBC, although several aspects remain unstudied. Interleukins (ILs) play an important role in cancer as potential modulators of angiogenesis, leukocyte infiltration and tumor growth. The aims of the present study were to assess serum and tumor levels of several ILs (IL-1α, IL-1β, IL-6, IL-8 and IL-10) by enzyme-immunoassay in dogs bearing benign and malignant mammary tumors, including dogs with IMC, for a better understanding of this disease. Forty-eight dogs were prospectively included. Animals consisted of 7 healthy Beagles used as donors for normal mammary glands (NMG) and serum controls (SCs), 10 dogs with hyperplasias and benign mammary tumors (HBMT), 24 with non-inflammatory malignant mammary tumors (non-IMC MMT) and 7 dogs with clinical and pathological IMC. IL-8 (serum) and IL-10 (serum and tissue homogenate) levels were higher in the dogs with IMC compared with the non-IMC MMT group. ILs were increased with tumor malignancy as follows: in tumor homogenates IL-6 levels were higher in malignant tumors (IMC and non-IMC MMT) versus HBMT and versus NMG and tumor IL-8 was increased in malignant tumors versus NMG; in serum, IL-1α and IL-8 levels were higher in the malignant groups respect to HBMT and SCs; interestingly, IL-10 was elevated only in the serum of IMC animals. To the best of our knowledge, this is the first report that analyzes ILs in IMC and IL-10 in canine mammary tumors. Our results indicate a role for IL-6, IL-8 and IL-10 in canine mammary malignancy and specific differences in ILs content in IMC versus non-IMC MMT that could have future diagnostic and therapeutic implications, to be confirmed in a larger series of IMC cases. These results help to support the validity of the IMC canine model for the study of human IBC and provide insight into this uncommon malignancy in dogs.

The role of the bone microenvironment in skeletal metastasis

The bone microenvironment provides a fertile soil for cancer cells. It is therefore not surprising that the skeleton is a frequent site of cancer metastasis. It is believed that reciprocal interactions between tumour and bone cells, known as the “vicious cycle of bone metastasis” support the establishment and orchestrate the expansion of malignant cancers in bone. While the full range of molecular mechanisms of cancer metastasis to bone remain to be elucidated, recent research has deepened our understanding of the cell-mediated processes that may be involved in cancer cell survival and growth in bone. This review aims to address the importance of the bone microenvironment in skeletal cancer metastasis and discusses potential therapeutic implications of novel insights.

Pairwise shared genomic segment analysis in three Utah high-risk breast cancer pedigrees

Background

We applied a new weighted pairwise shared genomic segment (pSGS) analysis for susceptibility gene localization to high-density genomewide SNP data in three extended high-risk breast cancer pedigrees.

Results

Using this method, four genomewide suggestive regions were identified on chromosomes 2, 4, 7 and 8, and a borderline suggestive region on chromosome 14. Seven additional regions with at least nominal evidence were observed. Of particular note among these total twelve regions were three regions that were identified in two pedigrees each; chromosomes 4, 7 and 14. Follow-up two-pedigree pSGS analyses further indicated excessive genomic sharing across the pedigrees in all three regions, suggesting that the underlying susceptibility alleles in those regions may be shared in common. In general, the pSGS regions identified were quite large (average 32.2 Mb), however, the range was wide (0.3 – 88.2 Mb). Several of the regions identified overlapped with loci and genes that have been previously implicated in breast cancer risk, including NBS1, BRCA1 and RAD51L1.

Conclusions

Our analyses have provided several loci of interest to pursue in these high-risk pedigrees and illustrate the utility of the weighted pSGS method and extended pedigrees for gene mapping in complex diseases. A focused sequencing effort across these loci in the sharing individuals is the natural next step to further map the critical underlying susceptibility variants in these regions.

Effect of standard anthracycline based neoadjuvant chemotherapy on circulating levels of serum IL-6 in patients of locally advanced carcinoma breast - a prospective study

BACKGROUND

Elevated IL-6 levels have been associated with advanced stage of breast cancer and metastasis-related morbidity. The present prospective study was carried out to assess the effect of neoadjuvant chemotherapy on circulating levels of serum IL-6 in patients of locally advanced carcinoma breast.

MATERIALS

All locally advanced carcinoma breast cases presenting to the surgery out patient's department were included in the study excluding pregnant or lactating females and those patients who were unfit for anthracycline based chemotherapy. A total of 30 cases were included. The various parameters that were evaluated include detailed clinico-pathological profile and IL-6 levels. Clinical staging using TNM classification was performed in all enrolled patients. This included documenting tumor size (on USG), node status and metastatic workup. First blood sample was collected before start of any treatment. Second blood sample was collected after 3 cycles of chemotherapy. Blood was centrifuged within 30 min and serum kept at -80 °C until analysis for IL-6. IL-6 levels were quantified by ELISA.

RESULTS

Majority of patients presented in stage T3N1M0 (66.66%). The serum level of IL-6 increased as the disease progressed from T3N1M0 to T4dN2M0 (41.4 ± 31.9 pg/ml vs. 164.0 ± 31.1 pg/ml respectively). A progressive reduction in IL-6 levels with subsequent cycles of chemotherapy was observed which was statistically significant (from 72.8 ± 56.0 pg/ml to 47.0 ± 61.9 pg/ml; p value 0.002 wilcoxan signed rank test).

CONCLUSION

Our study shows a consistent decline in the IL-6 levels with chemotherapy. Upon ratification of our findings by large population based multi centric studies, we may state with conviction that a single blood test as serum level of IL6 will prove beneficial in assessing the efficacy of chemotherapy.

Cytokines, obesity, and cancer: new insights on mechanisms linking obesity to cancer risk and progression

Obesity is a problem of epidemic proportions in many developed nations. Increased body mass index and obesity are associated with a significantly worse outcome for many cancers. Breast cancer risk in the postmenopausal setting and poor disease outcome for all patients is significantly augmented in overweight and obese individuals. The expansion of fat tissue involves a complex interaction of endocrine factors known as adipokines and cytokines. High cytokine levels in primary breast cancers and in the circulation of affected patients have been associated with poor outcome. This review summarizes the how cytokine production in obese adipose tissue creates a chronic inflammatory microenvironment that favors tumor cell motility, invasion, and epithelial-mesenchymal transition to enhance the metastatic potential of tumor cells. Many of the cytokines associated with a proinflammatory state are not only upregulated in obese adipose tissue but may also stimulate the self-renewal of cancer stem cells. Thus, enhanced cytokine production in obese adipose tissue may serve both as a chemoattractant for invading cancers and to augment their malignant potential. These new mechanistic insights suggest that the current obesity epidemic will presage a significant increase in cancer incidence, morbidity, and mortality in the next few decades.

Camel urine components display anti-cancer properties in vitro

ETHNOPHARMACOLOGICAL RELEVANCE

While camel urine (CU) is widely used in the Arabian Peninsula to treat various diseases, including cancer, its exact mechanism of action is still not defined. The objective of the present study is to investigate whether camel urine has anti-cancer effect on human cells in vitro.

MATERIALS AND METHODS

The annexinV/PI assay was used to assess apoptosis, and immunoblotting analysis determined the effect of CU on different apoptotic and oncogenic proteins. Furthermore, flow cytometry and Elispot were utilized to investigate cytotoxicity and the effect on the cell cycle as well as the production of cytokines, respectively.

RESULTS

Camel urine showed cytotoxicity against various, but not all, human cancer cell lines, with only marginal effect on non-tumorigenic epithelial and normal fibroblast cells epithelial and fibroblast cells. Interestingly, 216 mg/ml of lyophilized CU inhibited cell proliferation and triggered more than 80% of apoptosis in different cancer cells, including breast carcinomas and medulloblastomas. Apoptosis was induced in these cells through the intrinsic pathway via Bcl-2 decrease. Furthermore, CU down-regulated the cancer-promoting proteins survivin, β-catenin and cyclin D1 and increased the level of the cyclin-dependent kinase inhibitor p21. In addition, we have shown that CU has no cytotoxic effect against peripheral blood mononuclear cells and has strong immuno-inducer activity through inducing IFN-γ and inhibiting the Th2 cytokines IL-4, IL-6 and IL-10.

CONCLUSIONS

CU has specific and efficient anti-cancer and potent immune-modulator properties in vitro.

A two-SNP IL-6 promoter haplotype is associated with increased lung cancer risk

BACKGROUND

Aberrant expression of interleukin-6 (IL-6) may play an important role in lung carcinogenesis. Whether IL-6 promoter haplotypes are associated with lung cancer risk and their functions have not yet been studied. We tested the hypothesis that single-nucleotide polymorphism (SNP) and/or haplotypes of IL-6 promoter are associated with risk of lung cancer.

METHODS

Two functional IL-6 promoter SNPs (-6331T>C and -572C>G) were genotyped in the discovery group including 622 patients and 614 controls, and the results were replicated in an independent validation group including 615 patients and 638 controls. Luciferase reporter gene assays were conducted to examine the function of IL-6 promoter haplotypes.

RESULTS

None of the functional IL-6 promoter SNPs were associated with lung cancer risk in either study. However, a two-SNP CC (-6331C and -572C) IL-6 promoter haplotype was significantly more common among cases than among controls in both groups (P = 0.031 and P = 0.035, respectively), indicating that this haplotype is associated with increased lung cancer risk {adjusted odds ratio [OR], 1.56 [95 % confidence interval (95 % CI), 1.04-2.34] and 1.51 [95 % CI, 1.03-2.22], respectively}. Combined analysis of both studies showed a strong association of this two-SNP haplotype with increased lung cancer risk (adjusted OR, 1.53; 95 % CI, 1.16-2.03; P = 0.003). Comparably, luciferase reporter assays of A549 lung cancer cell lines transfected with the CC haplotype revealed that the two-SNP haplotype had significantly higher IL-6 transcriptional activity compared with cells transfected with the common haplotype.

CONCLUSIONS

This is the first evidence of identifying an IL-6 promoter haplotype (CC) associated with increased risk of lung cancer.

IL-6 upregulation contributes to the reduction of miR-26a expression in hepatocellular carcinoma cells

A recent study showed that miR-26a is downregulated in hepatocellular carcinoma tissues and that this downregulation is an independent predictor of survival. Interestingly, the same study also reported that miR-26a downregulation causes a concomitant elevation of IL-6 expression. Because miR-26a expression was found to be transcriptionally downregulated by oncogene c-Myc in various cancers, and the expression of c-Myc was increased by IL-6 stimulation, we hypothesized that IL-6 contributes to reduction of miR-26a in hepatocellular carcinoma. Serum IL-6 was measured by ELISA and miR-26a was detected by qRT-PCR. The data of 30 patients with hepatocellular carcinoma who had undergone surgical tumor resection revealed that serum IL-6 could be considered to be a predictor of survival up to 5 years for hepatocellular carcinoma patients (log-rank test, P < 0.05). We observed that the serum IL-6 concentration was inversely correlated with miR-26a expression in cancerous tissues (Pearson correlation test, r = -0.651, P < 0.01). Furthermore, by in vitro experiments with HepG2 cells, we showed that IL-6 stimulation can lead to miR-26a suppression via c-Myc activation, whereas in normal hepatocyte LO2 cells incubation with IL-6 had no significant effect on miR-26a expression. Taken together, these results indicate that miR-26a reduction in hepatocellular carcinoma might be due to IL-6 upregulation.

Effects of a physical activity behavior change intervention on inflammation and related health outcomes in breast cancer survivors: pilot randomized trial

BACKGROUND

The goal of this pilot study was to determine the magnitude and direction of intervention effect sizes for inflammatory-related serum markers and relevant health outcomes among breast cancer survivors (BCSs) receiving a physical activity behavior change intervention compared with usual care.

METHODS

This randomized controlled trial enrolled 28 stage I, II, or IIIA BCSs who were post-primary treatment and not regular exercisers. Participants were assigned to either a 3-month physical activity behavior change intervention group (ING) or usual care group (UCG). Intervention included supervised aerobic (150 weekly minutes, moderate-intensity) and resistance (2 sessions per week) exercise that gradually shifted to home-based exercise. Outcomes were assessed at baseline and 3 months.

RESULTS

Cardiorespiratory fitness significantly improved in the ING versus the UCG (between-group difference = 3.8 mL/kg/min; d = 1.1; P = .015). Self-reported sleep latency was significantly reduced in the ING versus the UCG (between group difference = -0.5; d = -1.2; P = .02) as was serum leptin (between-group difference = -9.0 ng/mL; d = -1.0; P = .031). Small to medium nonsignificant negative effect sizes were noted for interleukin (IL)-10 and tumor necrosis factor (TNF)-α and ratios of IL-6 to IL-10, IL-8 to IL-10, and TNF-α to IL-10, whereas nonsignificant positive effect sizes were noted for IL-6 and high-molecular-weight adiponectin.

CONCLUSIONS

Physical activity behavior change interventions in BCSs can achieve large effect size changes for several health outcomes. Although effect sizes for inflammatory markers were often small and not significant, changes were in the hypothesized direction for all except IL-6 and IL-10.

Fatigue and sleep quality are associated with changes in inflammatory markers in breast cancer patients undergoing chemotherapy

Fatigue and sleep disturbances are two of the most common and distressing symptoms reported by cancer patients. Fatigue and sleep are also correlated with each other. While fatigue has been reported to be associated with some inflammatory markers, data about the relationship between cancer-related sleep disturbances and inflammatory markers are limited. This study examined the relationship between fatigue and sleep, measured both subjectively and objectively, and inflammatory markers in a sample of breast cancer patients before and during chemotherapy. Fifty-three women with newly diagnosed stage I-III breast cancer scheduled to receive at least four 3-week cycles of chemotherapy participated in this longitudinal study. Fatigue was assessed with the Multidimensional Fatigue Symptom Inventory-Short Form (MFSI-SF), sleep quality was assessed with the Pittsburgh Sleep Quality Index (PSQI) and objective sleep was measured with actigraphy. Three inflammatory markers were examined: Interleukin-6 (IL-6), Interleukin-1 receptor antagonist (IL-1RA) and C-reactive protein (CRP). Data were collected before (baseline) and during cycle 1 and cycle 4 of chemotherapy. Compared to baseline, more fatigue was reported, levels of IL-6 increased and IL-1RA decreased during chemotherapy. Reports of sleep quality remained poor. Mixed model analyses examining changes from baseline to each treatment time point revealed overall positive relationships between changes in total MFSI-SF scores and IL-6, between changes in total PSQI scores and IL-6 and IL-1RA, and between total wake time at night and CRP (all p's<0.05). These relationships suggest that cancer-related fatigue and sleep disturbances may share common underlying biochemical mechanisms.

STAT3 activation by IL-6 from mesenchymal stem cells promotes the proliferation and metastasis of osteosarcoma

We previously demonstrated that human mesenchymal stem cells (MSCs) promote the growth of osteosarcoma in the bone microenvironment. The aim of the present study was to further determine the effect of IL-6/STAT3 signaling on the progression of osteosarcoma. First, conditioned medium from MSCs was used to stimulate the growth of osteosarcoma cells (Saos-2) in vitro. We found that STAT3 was activated and that the activation could be blocked by an IL-6-neutralizing antibody. The inhibition of STAT3 in Saos-2 cells by siRNA or AG490 decreased cell proliferation, migration and invasion, down-regulated the mRNA expression of Cyclin D, Bcl-xL and Survivin and enhanced the apoptotic response. Furthermore, a nude mouse osteosarcoma model was established by injecting luciferase-labeled Saos-2 cells into the tibia, and the effect of STAT3 on tumor growth was determined by treating the mice with AG490. In vivo bioluminescence images showed that tumor growth was dramatically reduced in the AG490 group. In addition, STAT3 inhibition decreased the lung metastasis rate and prolonged the survival of these mice. After treatment with AG490, the protein levels of IL-6, p-STAT3 and PCNA were decreased, and the level of apoptosis in the tumor was increased. Altogether, these data indicate that MSCs in the bone microenvironment might promote the progression of osteosarcoma and protect tumor cells from drug-induced apoptosis through IL-6/STAT3 signaling.

Minireview: Inflammation: an instigator of more aggressive estrogen receptor (ER) positive breast cancers

Approximately 75% of breast tumors express the estrogen receptor (ER), and women with these tumors will receive endocrine therapy. Unfortunately, up to 50% of these patients will fail ER-targeted therapies due to either de novo or acquired resistance. ER-positive tumors can be classified based on gene expression profiles into Luminal A- and Luminal B-intrinsic subtypes, with distinctly different responses to endocrine therapy and overall patient outcome. However, the underlying biology causing this tumor heterogeneity has yet to become clear. This review will explore the role of inflammation as a risk factor in breast cancer as well as a player in the development of more aggressive, therapy-resistant ER-positive breast cancers. First, breast cancer risk factors, such as obesity and mammary gland involution after pregnancy, which can foster an inflammatory microenvironment within the breast, will be described. Second, inflammatory components of the tumor microenvironment, including tumor-associated macrophages and proinflammatory cytokines, which can act on nearby breast cancer cells and modulate tumor phenotype, will be explored. Finally, activation of the nuclear factor κB (NF-κB) pathway and its cross talk with ER in the regulation of key genes in the promotion of more aggressive breast cancers will be reviewed. From these multiple lines of evidence, we propose that inflammation may promote more aggressive ER-positive tumors and that combination therapy targeting both inflammation and estrogen production or actions could benefit a significant portion of women whose ER-positive breast tumors fail to respond to endocrine therapy.

AS601245, an Anti-Inflammatory JNK Inhibitor, and Clofibrate Have a Synergistic Effect in Inducing Cell Responses and in Affecting the Gene Expression Profile in CaCo-2 Colon Cancer Cells

PPARαs are nuclear receptors highly expressed in colon cells. They can be activated by the fibrates (clofibrate, ciprofibrate etc.) used to treat hyperlipidemia. Since PPARα transcriptional activity can be negatively regulated by JNK, the inhibition of JNK activity could increase the effectiveness of PPARα ligands. We analysed the effects of AS601245 (a JNK inhibitor) and clofibrate alone or in association, on proliferation, apoptosis, differentiation and the gene expression profile of CaCo-2 human colon cancer cells. Proliferation was inhibited in a dose-dependent way by clofibrate and AS601245. Combined treatment synergistically reduced cell proliferation, cyclin D1 and PCNA expression and induced apoptosis and differentiation. Reduction of cell proliferation, accompanied by the modulation of p21 expression was observed in HepG2 cells, also. Gene expression analysis revealed that some genes were highly modulated by the combined treatment and 28 genes containing PPRE were up-regulated, while clofibrate alone was ineffective. Moreover, STAT3 signalling was strongly reduced by combined treatment. After combined treatment, the binding of PPARα to PPRE increased and paralleled with the expression of the PPAR coactivator MED1. Results demonstrate that combined treatment increases the effectiveness of both compounds and suggest a positive interaction between PPARα ligands and anti-inflammatory agents in humans.

IL-6/IL-6R as a potential key signaling pathway in prostate cancer development

Interleukin-6 (IL-6) is a pleiotropic cytokine involved in prostate regulation and in prostate cancer (PC) development/progression. IL-6 acts as a paracrine and autocrine growth stimulator in benign and tumor prostate cells. The levels of IL-6 and respective receptors are increased during prostate carcinogenesis and tumor progression. Several studies reported that increased serum and plasma IL-6 and soluble interleukin-6 receptor levels are associated with aggressiveness of the disease and are associated with a poor prognosis in PC patients. In PC treatment, patients diagnosed with advanced stages are frequently submitted to hormonal castration, although most patients will eventually fail this therapy and die from recurrent castration-resistant prostate cancer (CRPC). Therefore, it is important to understand the mechanisms involved in CRPC. Several pathways have been proposed to be involved in CRPC development, and their understanding will improve the way to more effective therapies. In fact, the prostate is known to be dependent, not exclusively, on androgens, but also on growth factors and cytokines. The signaling pathway mediated by IL-6 may be an alternative pathway in the CRPC phenotype acquisition and cancer progression, under androgen deprivation conditions. The principal goal of this review is to evaluate the role of IL-6 pathway signaling in human PC development and progression and discuss the interaction of this pathway with the androgen recepto pathway. Furthermore, we intend to evaluate the inclusion of IL-6 and its receptor levels as a putative new class of tumor biomarkers.The IL-6/IL-6R signaling pathway may be included as a putative molecular marker for aggressiveness in PC and it may be able to maintain tumor growth through the AR pathway under androgen-deprivation conditions. The importance of the IL-6/IL-6R pathway in regulation of PC cells makes it a good candidate for targeted therapy.

Improving gene expression data interpretation by finding latent factors that co-regulate gene modules with clinical factors

Background

In the analysis of high-throughput data with a clinical outcome, researchers mostly focus on genes/proteins that show first-order relations with the clinical outcome. While this approach yields biomarkers and biological mechanisms that are easily interpretable, it may miss information that is important to the understanding of disease mechanism and/or treatment response. Here we test the hypothesis that unobserved factors can be mobilized by the living system to coordinate the response to the clinical factors.

Results

We developed a computational method named Guided Latent Factor Discovery (GLFD) to identify hidden factors that act in combination with the observed clinical factors to control gene modules. In simulation studies, the method recovered masked factors effectively. Using real microarray data, we demonstrate that the method identifies latent factors that are biologically relevant, and extracts more information than analyzing only the first-order response to the clinical outcome.

Conclusions

Finding latent factors using GLFD brings extra insight into the mechanisms of the disease/drug response. The R code of the method is available at http://userwww.service.emory.edu/~tyu8/GLFD.

Inflamm-aging of the stem cell niche: breast cancer as a paradigmatic example: breakdown of the multi-shell cytokine network fuels cancer in aged people

Inflamm-aging is a relatively new terminology used to describe the age-related increase in the systemic pro-inflammatory status of humans. Here, we represent inflamm-aging as a breakdown in the multi-shell cytokine network, in which stem cells and stromal fibroblasts (referred to as the stem cell niche) become pro-inflammatory cytokine over-expressing cells due to the accumulation of DNA damage. Inflamm-aging self-propagates owing to the capability of pro-inflammatory cytokines to ignite the DNA-damage response in other cells surrounding DNA-damaged cells. Macrophages, the major cellular player in inflamm-aging, amplify the phenomenon, by broadcasting pro-inflammatory signals at both local and systemic levels. On the basis of this, we propose that inflamm-aging is a major contributor to the increase in cancer incidence and progression in aged people. Breast cancer will be presented as a paradigmatic example for this relationship.

Role of interleukin-10 in breast cancer

Cytokines are low molecular weight regulatory proteins or glycoprotein that modulates the intensity and duration of immune response by stimulating or inhibiting the activation, proliferation, and/or differentiation of target cells. Different cytokines are known to have diverse role in breast cancer initiation and progression. Interleukin-10 (IL-10), a pleiotropic anti-inflammatory cytokine, induces immunosuppression and assists in escape from tumor immune surveillance. Like several other cytokines, IL-10 also can exert dual proliferative and inhibitory effect on breast tumor cells indicating a complex role of IL-10 in breast cancer initiation and progression. In this review, we tried to put together a comprehensive current view on significance of IL-10 in promotion, inhibition, and importance as prognosticator in breast cancer based on in vitro, in vivo, and clinical evidences. For literature collection, we conducted PubMed search with keywords "IL-10" and "breast cancer".

Hsp27 participates in the maintenance of breast cancer stem cells through regulation of epithelial-mesenchymal transition and nuclear factor-κB

Introduction

Heat shock proteins (HSPs) are normally induced under environmental stress to serve as chaperones for maintenance of correct protein folding but they are often overexpressed in many cancers, including breast cancer. The expression of Hsp27, an ATP-independent small HSP, is associated with cell migration and drug resistance of breast cancer cells. Breast cancer stem cells (BCSCs) have been identified as a subpopulation of breast cancer cells with markers of CD24-CD44+ or high intracellular aldehyde dehydrogenase activity (ALDH+) and proved to be associated with radiation resistance and metastasis. However, the involvement of Hsp27 in the maintenance of BCSC is largely unknown.

Methods

Mitogen-activated protein kinase antibody array and Western blot were used to discover the expression of Hsp27 and its phosphorylation in ALDH + BCSCs. To study the involvement of Hsp27 in BCSC biology, siRNA mediated gene silencing and quercetin treatment were used to inhibit Hsp27 expression and the characters of BCSCs, which include ALDH+ population, mammosphere formation and cell migration, were analyzed simultaneously. The tumorigenicity of breast cancer cells after knockdown of Hsp27 was analyzed by xenograftment assay in NOD/SCID mice. The epithelial-mesenchymal transition (EMT) of breast cancer cells was analyzed by wound-healing assay and Western blot of snail, vimentin and E-cadherin expression. The activation of nuclear factor kappa B (NF-κB) was analyzed by luciferase-based reporter assay and nuclear translocation.

Results

Hsp27 and its phosphorylation were increased in ALDH+ BCSCs in comparison with ALDH- non-BCSCs. Knockdown of Hsp27 in breast cancer cells decreased characters of BCSCs, such as ALDH+ population, mammosphere formation and cell migration. In addition, the in vivo CSC frequency could be diminished in Hsp27 knockdown breast cancer cells. The inhibitory effects could also be observed in cells treated with quercetin, a plant flavonoid inhibitor of Hsp27, and it could be reversed by overexpression of Hsp27. Knockdown of Hsp27 also suppressed EMT signatures, such as decreasing the expression of snail and vimentin and increasing the expression of E-cadherin. Furthermore, knockdown of Hsp27 decreased the nuclear translocation as well as the activity of NF-κB in ALDH + BCSCs, which resulted from increasing expression of IκBα. Restored activation of NF-κB by knockdown of IκBα could reverse the inhibitory effect of Hsp27 siRNA in suppression of ALDH+ cells.

Conclusions

Our data suggest that Hsp27 regulates the EMT process and NF-κB activity to contribute the maintenance of BCSCs. Targeting Hsp27 may be considered as a novel strategy in breast cancer therapy.

The JAK2/STAT3 signaling pathway is required for growth of CD44⁺CD24⁻ stem cell-like breast cancer cells in human tumors

Intratumor heterogeneity is a major clinical problem because tumor cell subtypes display variable sensitivity to therapeutics and may play different roles in progression. We previously characterized 2 cell populations in human breast tumors with distinct properties: CD44+CD24- cells that have stem cell-like characteristics, and CD44-CD24+ cells that resemble more differentiated breast cancer cells. Here we identified 15 genes required for cell growth or proliferation in CD44+CD24- human breast cancer cells in a large-scale loss-of-function screen and found that inhibition of several of these (IL6, PTGIS, HAS1, CXCL3, and PFKFB3) reduced Stat3 activation. We found that the IL-6/JAK2/Stat3 pathway was preferentially active in CD44+CD24- breast cancer cells compared with other tumor cell types, and inhibition of JAK2 decreased their number and blocked growth of xenografts. Our results highlight the differences between distinct breast cancer cell types and identify targets such as JAK2 and Stat3 that may lead to more specific and effective breast cancer therapies.

Transglutaminase 2 facilitates the distant hematogenous metastasis of breast cancer by modulating interleukin-6 in cancer cells

Introduction

Inflammation has been implicated in cancer aggressiveness. As transglutaminase 2 (TG2), which has been associated with inflammatory signaling, has been suggested to play a role in tumor behavior, we propose that TG2 may be an important linker inducing interleukin (IL)-6-mediated cancer-cell aggressiveness, including distant hematogenous metastasis.

Methods

To investigate the role for TG2 and IL-6, TG2-knocked-down and IL-6-knocked-down cancer cells were generated by using shRNA. Human breast cancer cell xenograft model in highly immunocompromised mice and human advanced breast cancer primary tumor tissue microarrays were used in this study.

Results

IL-6 production in human breast cancer cells was dependent on their TG2 expression level. In vitro tumor-sphere formation was dependent on TG2 and downstream IL-6 production from cancer cells. Primary tumor growth in the mammary fat pads and distant hematogenous metastasis into the lung was also dependent on TG2 and downstream IL-6 expression levels. The effect of TG2 expression on human breast cancer distant metastasis was investigated by analyzing a tissue microarray of primary tumors from 412 patients with their clinical data after 7 years. TG2 expression in primary tumor tissue was inversely correlated with recurrence-free survival (P = 0.019) and distant metastasis-free survival (DMFS) (P = 0.006) in patients with advanced breast cancer. Furthermore, by using public datasets that included a total of 684 breast cancer patients, we found that the combined high expression of TG2 and IL-6 was associated with shorter DMFS, compared with the high expression of IL-6 only (P = 0.013).

Conclusions

We provide evidence that TG2 is an important link in IL-6-mediated tumor aggressiveness, and that TG2 could be an important mediator of distant metastasis, both in a xenograft animal model and in patients with advanced breast cancer.

Signal transducers and activators of transcription 3 (STAT3) directly regulates cytokine-induced fascin expression and is required for breast cancer cell migration

The cytokines oncostatin M (OSM) and IL-6 promote breast cancer cell migration and metastasis. Both cytokines activate STAT3, a member of the STAT (signal transducers and activators of transcription) family of transcription factors. Through transcriptional regulation of its target genes, STAT3 controls a wide range of cellular processes, including cellular proliferation, oncogenesis, and cancer metastasis. Fascin is an actin-bundling protein involved in cell migration. Elevated levels of fascin expression are found in many metastatic cancers, and inhibition of fascin function by small chemical compounds leads to a block of tumor metastasis. In this work, we demonstrate that fascin is a direct STAT3 target gene in response to OSM and IL-6 in both mouse and human breast cancer cells. We show that NFκB also binds to the fascin promoter in response to cytokine treatment and this binding is STAT3-dependent. Both STAT3 and NFκB are required for the cytokine-induced expression of fascin in cancer cells. Furthermore, we demonstrate that STAT3, in directly controlling fascin expression, is both necessary and sufficient for breast cancer cell migration.

IL-6 trans-signaling licenses mouse and human tumor microvascular gateways for trafficking of cytotoxic T cells

Immune cells are key regulators of neoplastic progression, which is often mediated through their release of cytokines. Inflammatory cytokines such as IL-6 exert tumor-promoting activities by driving growth and survival of neoplastic cells. However, whether these cytokines also have a role in recruiting mediators of adaptive anticancer immunity has not been investigated. Here, we report that homeostatic trafficking of tumor-reactive CD8+ T cells across microvascular checkpoints is limited in tumors despite the presence of inflammatory cytokines. Intravital imaging in tumor-bearing mice revealed that systemic thermal therapy (core temperature elevated to 39.5°C ± 0.5°C for 6 hours) activated an IL-6 trans-signaling program in the tumor blood vessels that modified the vasculature such that it could support enhanced trafficking of CD8+ effector/memory T cells (Tems) into tumors. A concomitant decrease in tumor infiltration by Tregs during systemic thermal therapy resulted in substantial enhancement of Tem/Treg ratios. Mechanistically, IL-6 produced by nonhematopoietic stromal cells acted cooperatively with soluble IL-6 receptor-α and thermally induced gp130 to promote E/P-selectin- and ICAM-1-dependent extravasation of cytotoxic T cells in tumors. Parallel increases in vascular adhesion were induced by IL-6/soluble IL-6 receptor-α fusion protein in mouse tumors and patient tumor explants. Finally, a causal link was established between IL-6-dependent licensing of tumor vessels for Tem trafficking and apoptosis of tumor targets. These findings suggest that the unique IL-6-rich tumor microenvironment can be exploited to create a therapeutic window to boost T cell-mediated antitumor immunity and immunotherapy.

Inhibiting signal transducer and activator of transcription 3: rationality and rationale design of inhibitors

INTRODUCTION

Signal transducer and activator of transcription 3 (STAT3) controls a key signaling pathway in the development of many malignant diseases. Several genetic studies have proven its central role in the regulation of apoptosis, proliferation, angiogenesis and immune responses making it an attractive target for cancer therapy.

AREAS COVERED

This article addresses the role of STAT3 in immune response modulation and highlights the contribution of STAT3 in inflammation-mediated tumorigenesis. We also review the rationale to use novel STAT3 inhibitors and list some of these inhibitors such as STA-21, IS3 295, S3I- M2001 and small molecule JAK2 inhibitors AZD1480 and AZ960 that have been found to be efficient against tumors. We summarize the efforts that have been made so far in identifying promising compounds and mention the barriers that need to be overcome for successful application of STAT3 inhibitors in clinics.

EXPERT OPINION

STAT3 is an important target in tumor biology based on its frequent activation in various tumors and its pleiotropic effects on different cell types. Screening large libraries of logically synthesized small molecule inhibitors is one way to rapidly generate many potential molecules, which can then be tested in different biologically relevant models. The stage is, therefore, set for the identification and development of novel STAT3 inhibitors that will, in the very near future, enter the clinical realm.

Cancer-associated adipocytes exhibit an activated phenotype and contribute to breast cancer invasion

Early local tumor invasion in breast cancer results in a likely encounter between cancer cells and mature adipocytes, but the role of these fat cells in tumor progression remains unclear. We show that murine and human tumor cells cocultivated with mature adipocytes exhibit increased invasive capacities in vitro and in vivo, using an original two-dimensional coculture system. Likewise, adipocytes cultivated with cancer cells also exhibit an altered phenotype in terms of delipidation and decreased adipocyte markers associated with the occurrence of an activated state characterized by overexpression of proteases, including matrix metalloproteinase-11, and proinflammatory cytokines [interleukin (IL)-6, IL-1β]. In the case of IL-6, we show that it plays a key role in the acquired proinvasive effect by tumor cells. Equally important, we confirm the presence of these modified adipocytes in human breast tumors by immunohistochemistry and quantitative PCR. Interestingly, the tumors of larger size and/or with lymph nodes involvement exhibit the higher levels of IL-6 in tumor surrounding adipocytes. Collectively, all our data provide in vitro and in vivo evidence that (i) invasive cancer cells dramatically impact surrounding adipocytes; (ii) peritumoral adipocytes exhibit a modified phenotype and specific biological features sufficient to be named cancer-associated adipocytes (CAA); and (iii) CAAs modify the cancer cell characteristics/phenotype leading to a more aggressive behavior. Our results strongly support the innovative concept that adipocytes participate in a highly complex vicious cycle orchestrated by cancer cells to promote tumor progression that might be amplified in obese patients.

HER2 overexpression elicits a proinflammatory IL-6 autocrine signaling loop that is critical for tumorigenesis

HER2 overexpression occurs in approximately 25% of breast cancers, where it correlates with poor prognosis. Likewise, systemic inflammation in breast cancer correlates with poor prognosis, although the process is not understood. In this study, we explored the relationship between HER2 and inflammation, comparing the effects of overexpressing wild-type or mutated inactive forms of HER2 in primary human breast cells. Wild-type HER2 elicited a profound transcriptional inflammatory profile, including marked elevation of interleukin-6 (IL-6) expression, which we established to be a critical determinant of HER2 oncogenesis. Mechanistic investigations revealed that IL-6 secretion induced by HER2 overexpression activated Stat3 and altered gene expression, enforcing an autocrine loop of IL-6/Stat3 expression. Both mouse and human in vivo models of HER2-amplified breast carcinoma relied critically on this HER2-IL-6-Stat3 signaling pathway. Our studies offer the first direct evidence linking HER2 to a systemic inflammatory mechanism that orchestrates HER2-mediated tumor growth. We suggest that the HER2-IL-6-STAT3 signaling axis we have defined in breast cancer could prompt new therapeutic or prevention strategies for treatment of HER2-amplified cancers.

Novel small molecule, XZH-5, inhibits constitutive and interleukin-6-induced STAT3 phosphorylation in human rhabdomyosarcoma cells

Signal transducers and activators of transcription 3 (STAT3) signaling is constitutively activated in many types of human cancers and cancer cell lines and represents a promising target for cancer therapy. We previously reported that the STAT3 signaling pathway is constitutively activated in human rhabodomyosarcoma cell lines (RH28, RH30 and RD2). We also demonstrated that inhibition of the STAT3 pathway led to apoptosis in human rhabdomyosarcoma cells. In the present study, we investigated the inhibitory effects of a novel small molecule, XZH-5, on the STAT3 signaling pathway in human rhabdomyosarcoma cells. XZH-5 was designed based on STAT3 structure, and our idea was to design peptide mimics to bind to the phosphorylated Tyr705 site and the side pocket. We found that XZH-5 downregulated STAT3 phosphorylation. The inhibition of STAT3 by XZH-5 was confirmed by the inhibition of STAT3 DNA binding ability and the downregulation of STAT3 downstream genes, such as Bcl-2, Bcl-xL, Cyclin D1 and Survivin; we also demonstrated that blockade of STAT3 phosphorylation in human rhabdomyosarcoma cells with XZH-5 caused apoptosis and suppressed colony-forming ability and cell migration. In addition to reducing constitutive STAT3 phosphorylation, XZH-5 also exhibited the potency to block interleukin-6 (IL-6)-induced STAT3 phosphorylation and nuclear translocation but did not inhibit the stimulation of STAT1 phosphorylation by interferon (IFN)-γ. Our findings indicate that XZH-5 has the potential for targeting human rhabdomyosarcoma cells expressing constitutive STAT3.