Anti-interleukin-6 receptor antibody inhibits the progression in human colon carcinoma cells

Targeting interleukin-6 as a treatment approach for peritoneal carcinomatosis

Peritoneal carcinomatosis (PC) is a complex manifestation of abdominal cancers, with a poor prognosis and limited treatment options. Recent work identifying high concentrations of the cytokine interleukin-6 (IL-6) and its soluble receptor (sIL-6-Rα) in the peritoneal cavity of patients with PC has highlighted this pathway as an emerging potential therapeutic target. This review article provides a comprehensive overview of the current understanding of the potential role of IL-6 in the development and progression of PC. We discuss mechansims by which the IL-6 pathway may contribute to peritoneal tumor dissemination, mesothelial adhesion and invasion, stromal invasion and proliferation, and immune response modulation. Finally, we review the prospects for targeting the IL-6 pathway in the treatment of PC, focusing on common sites of origin, including ovarian, gastric, pancreatic, colorectal and appendiceal cancer, and mesothelioma.

Tocilizumab Exerts Anti-Tumor Effects on Colorectal Carcinoma Cell Xenografts Corresponding to Expression Levels of Interleukin-6 Receptor

The use of tocilizumab against the interleukin-6 receptor (IL-6R) has been demonstrated as inhibiting the progression of diverse cancers in vitro and in vivo. Nonetheless, evidence regarding the anti-tumor effects of tocilizumab on human colorectal carcinoma (CRC) corresponding to IL-6R expression levels remains scarce. To investigate the influence of IL-6R expression, SW480 and HT-29 cells inoculated subcutaneously into NU/NU mice were used as human CRC xenograft models with anti-IL-6R antibody (tocilizumab) therapy. The IL-6R expression levels, histology of CRC growth/invasiveness, and tumor growth-related signaling pathway were estimated by H&E and immunohistochemical staining. SW480 tumor cells with higher IL-6R expression levels showed better responsiveness in tocilizumab therapy than in the treated HT-29 group. Likewise, therapeutic effects of tocilizumab on the proliferative ability with mitotic index and Ki-67 expressions, invasiveness with MMP-9 proteinase expressions, and ERK 1/2 and STAT3 signaling transduction in the SW480 treatment group were superior to the HT-29 treatment group. In light of our results, IL-6R is the key indicator for the efficacy of tocilizumab treatment in CRC xenografts. From the perspective of precision medicine, tumor response to anti-IL-6R antibody therapy could be predicted on the basis of IL-6R expression levels. In this manner, tocilizumab may serve as a targeted and promising anti-CRC therapy.

IL-6/JAK2-dependent G6PD phosphorylation promotes nucleotide synthesis and supports tumor growth

OBJECTIVE

Tumor cells hijack inflammatory mechanisms to promote their own growth. IL-6 is one of the major cytokines, and is frequently upregulated in tumors. The pentose phosphate pathway (PPP) generates the indispensable building blocks to produce various nucleotides. Here we aimed to determine whether and how PPP is timely tuned in response to IL-6 to support tumor growth.

METHODS

Protein expression was examined by immunoblot. Protein interaction was examined by immunoprecipitation. Tumor cell proliferation in in vitro culture was examined by BrdU assay and colony formation assay. Tumor cell proliferation in mouse xenograft model was examined by Ki-67 staining.

RESULTS

Here we show that the metabolic flux of PPP and enzymatic activity of glucose-6-phosphate dehydrogenase (G6PD) is rapidly induced under IL-6 treatment, without obvious changes in G6PD expression level. Mechanistically, Janus kinase 2 (JAK2) phosphorylates G6PD Y437 under IL-6 treatment, which accentuates G6PD enzymatic activity by promoting G6PD binding with its substrate G6P. Further, JAK2-dependent G6PD Y437 phosphorylation is required for IL-6-induced nucleotide biosynthesis and tumor cell proliferation, and is associated with the progression of oral squamous cell carcinoma.

CONCLUSIONS

Our findings report a new mechanism implicated in the crosstalk between tumor cells and inflammatory microenvironment, by which JAK2-dependent activation of G6PD governs nucleotide synthesis to support tumor cell proliferation, thereby highlighting its value as a potential anti-tumor target.

Anti-inflammatory activities of natural cyclopeptide RA-XII in colitis-associated colon cancer mouse model and its effect on gut microbiome

Colorectal cancer (CRC), the third most common cancer globally, is associated with intestinal inflammation that leads to poor prognosis. RA-XII, a natural cyclopeptide, has previously been reported to possess anti-tumor activities. Here, the anti-inflammatory activities of RA-XII were investigated in colitis-associated colon cancer mice and a co-culture in vitro model, in which colon cancer cells HCT116 and macrophages RAW264.7 were grown together to mimic the inflammatory microenvironment of CRC. Changes of inflammatory-related molecules and protein expressions in cells were evaluated after RA-XII incubation. Besides, azoxymethane and dextran sulfate sodium-induced colitis-associated colon cancer mice were treated with RA-XII for 24 days, inflammatory parameters and gut microbiome alterations were studied. Our results showed that RA-XII reversed the inflammatory responses of RAW264.7 cells induced by LPS and modulated the protein expressions of AKT, STAT3/p-STAT3, P70S6K, NF-κB and GSK3β and suppressed the expression of LC3A/B in HCT116 cells in co-culture system. RA-XII treatment restored the colitis damage in colon, reduced colon tumors numbers and decreased inflammatory factors (IL-6, IL-10 and TNF-α). The role of RA-XII on regulating gut microbiome was also demonstrated for the first time. In conclusion, our findings provided new scientific evidence for developing RA-XII as a potent anti-inflammatory agent for CRC.

The association between circulating levels of vitamin D and inflammatory markers in the first 2 years after colorectal cancer diagnosis

BACKGROUND

Calcitriol, the active form of vitamin D, may inhibit colorectal cancer (CRC) progression, which has been mechanistically linked to an attenuation of a pro-inflammatory state. The present study investigated the associations between circulating 25 hydroxy vitamin D₃ (25(OH)D₃) levels and inflammatory markers (IL10, IL8, IL6, TNFα and hsCRP) in the 2 years following CRC diagnosis.

METHODS

Circulating 25(OH)D₃ levels and inflammatory markers were assessed at diagnosis, after 6, 12 and 24 months from 798 patients with sporadic CRC participating in two prospective cohort studies. Associations between 25(OH)D₃ levels and individual inflammatory markers as well as a summary inflammatory z-score were assessed at each time point by multiple linear regression analyses. To assess the association between 25(OH)D₃ and inflammatory markers over the course of 2 years, linear mixed model regression analyses were conducted.

RESULTS

Higher 25(OH)D₃ levels were associated with lower IL6 levels at diagnosis, at 6 months after diagnosis and over the course of 2 years (β -0.06, 95% CI -0.08 to -0.04). In addition, 25(OH)D₃ levels were inversely associated with the summary inflammatory z-score at diagnosis and over the course of 2 years (β -0.17, 95% CI -0.25 to -0.08). In addition, a significant inverse association between 25(OH)D₃ levels and IL10 was found over the course of 2 years. Intra-individual analyses showed an inverse association between 25(OH)D₃ and IL10, IL6 and TNFα. No statistically significant associations between 25(OH)D₃ and IL8 and hsCRP levels were observed.

CONCLUSIONS

Serum 25(OH)D₃ levels were inversely associated with the summary inflammatory z-score and in particular with IL6 in the years following CRC diagnosis. This is of potential clinical relevance as IL6 has an important role in chronic inflammation and is also suggested to stimulate cancer progression. Further observational studies should investigate whether a possible 25(OH)D₃-associated reduction of inflammatory mediators influences treatment efficacy and CRC recurrence.

Effects of Anti-Cytokine Antibodies on Gut Barrier Function

Anti-cytokine antibodies are used in treating chronic inflammatory diseases and autoimmune diseases such as inflammatory bowel disease and rheumatic diseases. Patients with these diseases often have a compromised gut barrier function, suggesting that anti-cytokine antibodies may contribute to the re-establishment of gut barrier integrity, in addition to their immunomodulatory effects. This paper reviews the effects of anti-cytokine antibodies on gut barrier function and their mechanisms.

Current evidence for vitamin D in intestinal function and disease

Vitamin D activity is associated with the modulation of a wide variety of biological systems, in addition to its roles in calcium homeostatic mechanisms. While vitamin D is well known to promote gastrointestinal calcium absorption, vitamin D also plays a role in attenuating and/or preventing the progression of several gastrointestinal diseases including Crohn’s disease, ulcerative colitis, and colorectal cancer, and may also play a role in chemotherapy-induced intestinal mucositis. The pro-differentiation, immunomodulatory, and anti-inflammatory effects of vitamin D, which has been reported in numerous circumstances, are key potential mechanisms of action in the prevention of gastrointestinal disorders. While the debate of the effectiveness of vitamin D to treat bone pathologies continues, the clinical importance of vitamin D therapy to prevent gastrointestinal disorders should be investigated given current evidence, using both nutritional and pharmaceutical intervention approaches.

Impact statement

The non-skeletal functions of vitamin D play an important role in health and disease. The anti-inflammatory properties and maintenance of intestinal function fulfilled by vitamin D impact other systems in the body though downstream processing. This review provides insight into the mechanisms underpinning the potential benefits of vitamin D in both maintaining intestinal homeostasis and associated diseased states.

PIAS1 inhibited the metastasis of gastric cancer cell by epithelial-mesenchymal transition regulation within the inflammatory microenvironment

Protein inhibitor of activated signal transducer and activator of transcription-1 (PIAS1) is an important regulator of the inflammatory signaling network, the expression of which was decreased in gastric cancer and implicated in the development of cancer. However, its mechanism has not been elucidated. The aim of the present study was to investigate the effect of PIAS1 on epithelial-mesenchymal transition (EMT) of gastric cancer cells within the inflammatory microenvironment. Recombinant adenovirus Ad5/F35-PIASl and Ad5/F35-null plasmids were constructed to transfect SGC7901 cells. Subsequently, these plasmids were confirmed by reverse transcription polymerase chain reaction and western blotting. The cells were treated with IL-6 or Ad5/F35-PIASl+IL-6, and the control cells were treated with Ad5/F35-null+IL-6. The morphological changes to the cells were observed using inverted microscopy. The effect of PIAS1 on cell migration and invasion was evaluated by scratch wound healing and Transwell chamber assays, and the protein expression of EMT markers and phosphatidylinositol 3-kinase (PI3K)/serine/threonine-protein kinase (Akt)/matrix metalloproteinase (MMP)-9 signaling pathway was examined by western blotting. Transfection with Ad5/F35-PIASl markedly increased the PIAS1 expression in SGC7901 cells. The cells acquired the more typical spindle-shape phenotype of mesenchymal cells following co-culture with IL-6; the cells co-cultured with IL-6 and Ad5/F35-PIASl acquired changes concordant with an epithelial phenotype. The overexpression of PIAS1 significantly decreased the migratory and invasive capacities of the SGC7901 cells (P<0.01). Western blotting indicated that the expression levels of E-cadherin protein in the cells treated with Ad5/F35-PIASl+IL-6 were increased significantly and the expression levels of zinc finger protein SNAI, Twist-related protein 1, vimentin and MMP-9, and the activation of PI3K/Akt proteins were decreased when compared with IL-6- or Ad5/F35-null+IL-6-treated cells (both P<0.01). PIAS1 may inhibit EMT in gastric cancer cells within the inflammatory microenvironment via the regulation of PI3K/Akt pathway activation, and may serve an important role in the inhibition of tumor invasion and metastasis with in this microenvironment.

Human colorectal cancer-derived mesenchymal stem cells promote colorectal cancer progression through IL-6/JAK2/STAT3 signaling

Mesenchymal stem cells (MSCs) have been reported to localize in colorectal carcinomas, and participate in the formation of the tumor microenvironment. They have recently been isolated from colorectal cancer tissues, and are implicated in the growth, invasion, and metastasis of cancer cells. However, the roles and detailed mechanisms associated with human colorectal cancer-derived MSCs (CC-MSCs) have not been fully addressed. In this study, we found that CC-MSCs increased the migration and invasion of colorectal cancer cells and promoted the tumorigenesis of colorectal cancer through epithelial-to-mesenchymal transition (EMT) in vitro. We also found that CC-MSCs enhanced the growth and metastasis of colorectal cancer in vivo. Mechanistically, we determined that interleukin-6 (IL-6) was the most highly expressed cytokine in the CC-MSC conditioned medium, and promoted the progression of colorectal cancer cells through IL-6/JAK2/STAT3 signaling, which activated PI3K/AKT signaling. We used anti-IL-6 antibody to target IL-6. Collectively, these results reveal that the IL-6 secreted by CC-MSCs enhances the progression of colorectal cancer cells through IL-6/JAK2/STAT3 signaling, and could provide a novel therapeutic or preventive target.

Curcumin and Salsalate Suppresses Colonic Inflammation and Procarcinogenic Signaling in High-Fat-Fed, Azoxymethane-Treated Mice

High-fat diets (HFDs) and excess adiposity increase proinflammatory cytokines in the colon, altering gene expression in a manner that promotes the development of colorectal cancer (CRC). Thus, compounds that reduce this biochemical inflammation are potential chemopreventive agents. Curcumin (CUR), a dietary polyphenol, and salsalate (SAL), a non-steroidal anti-inflammatory drug, are both anti-inflammatories. We investigated the inhibitory effects of CUR with or without SAL on inflammatory cytokines and procarcinogenic signaling in azoxymethane (AOM)-treated A/J mice. A sub-tumorigenic AOM dose was chosen to produce a biochemical and molecular procarcinogenic colonic environment without tumors. Mice were fed either a HFD (60% of kilocalories) or low-fat diet (LFD) (10% of kilocalories). One HFD treatment group received 0.2% CUR in the diet; one received 0.2% CUR + 0.15% SAL; and one received 0.4% CUR + 0.3% SAL. The HFD mice developed 30% greater fat mass than the LFD mice (p < 0.05). The colonic concentrations of interleukin-1β (IL-1β) and interleukin-6 (IL-6) in the HFD mice were decreased by 50-69% by the high-dose combination regimen (p < 0.015). Only the combination regimens significantly suppressed phosphorylation of protein kinase B (Akt) and nuclear factor-κB (NF-κB) p65 (p < 0.044). The combination of CUR and SAL reduces the concentration of proinflammatory cytokines and diminishes activation of Akt and NF-κB more effectively than CUR alone, providing a scientific basis for examining whether this combination mitigates the risk of CRC in obese individuals.

Lysyl Oxidase Is a Strong Determinant of Tumor Cell Colonization in Bone

Lysyl oxidase (LOX) is a secreted copper-dependent amine oxidase whose primary function is to drive collagen crosslinking and extracellular matrix stiffness. LOX in colorectal cancer synergizes with hypoxia-inducible factor-1 (HIF-1) to promote tumor progression. Here we investigated whether LOX/HIF1 endows colorectal cancer cells with full competence for aggressive colonization in bone. We show that a high LOX expression in primary tumors from patients with colorectal cancer was associated with poor clinical outcome, irrespective of HIF-1 In addition, LOX was expressed by tumor cells in the bone marrow from colorectal cancer patients with bone metastases. In vivo experimental studies show that LOX overexpression in colorectal cancer cells or systemic delivery of the conditioned medium from LOX-overexpressing colorectal cancer cells promoted tumor cell dissemination in the bone marrow and enhanced osteolytic lesion formation, irrespective of HIF-1 Conversely, silencing or pharmacologic inhibition of LOX activity blocked dissemination of colorectal cancer cells in the bone marrow and tumor-driven osteolytic lesion formation. In vitro, tumor-secreted LOX supported the attachment and survival of colorectal cancer cells to and in the bone matrix, and inhibited osteoblast differentiation. LOX overexpression in colorectal cancer cells also induced a robust production of IL6. In turn, both LOX and IL6 were acting in concert to promote RANKL-dependent osteoclast differentiation, thereby creating an imbalance between bone resorption and bone formation. Collectively, our findings show that LOX supports colorectal cancer cell dissemination in the bone marrow and they reveal a novel mechanism through which LOX-driven IL6 production by colorectal cancer cells impairs bone homeostasis. Cancer Res; 77(2); 268-78. ©2016 AACR.

Colorectal cancer-promoting activity of the senescent peritoneal mesothelium

Gastrointestinal cancers metastasize into the peritoneal cavity in a process controlled by peritoneal mesothelial cells (HPMCs). In this paper we examined if senescent HPMCs can intensify the progression of colorectal (SW480) and pancreatic (PSN-1) cancers in vitro and in vivo. Experiments showed that senescent HPMCs stimulate proliferation, migration and invasion of SW480 cells, and migration of PSN-1 cells. When SW480 cells were injected i.p. with senescent HPMCs, the dynamics of tumor formation and vascularization were increased. When xenografts were generated using PSN-1 cells, senescent HPMCs failed to favor their growth. SW480 cells subjected to senescent HPMCs displayed up-regulated expression of transcripts for various pro-cancerogenic agents as well as increased secretion of their products. Moreover, they underwent an epithelial-mesenchymal transition in the Smad 2/3-Snail1-related pathway. The search for mediators of senescent HPMC activity showed that increased SW480 cell proliferation was stimulated by IL-6, migration by CXCL8 and CCL2, invasion by IL-6, MMP-3 and uPA, and epithelial-mesenchymal transition by TGF-β1. Secretion of these agents by senescent HPMCs was increased in an NF-κB- and p38 MAPK-dependent mechanism. Collectively, our findings indicate that in the peritoneum senescent HPMCs may create a metastatic niche in which critical aspects of cancer progression become intensified.

Ghrelin induces colon cancer cell proliferation through the GHS-R, Ras, PI3K, Akt, and mTOR signaling pathways

Colon cancer is the third most common malignancy worldwide. Recently, some interesting associations between ghrelin and cancer were reported, and it may participate in colon cancer development. In the present report, we explored the role of the growth hormone secretagogue receptor (GHS-R), Ras, phosphatidylinositol 3-kinase (PI3K), Akt, and mammalian target of rapamycin (mTOR) pathways in the ghrelin-induced proliferation of human colon cancer cells. Ghrelin-caused HT-29 proliferation was reduced by [D-Lys3]-GHRP-6 (a GHS-R inhibitor). We also found that a dominant negative mutant of Ras (Ras DN), a PI3K inhibitor (LY 294002), an Akt DN, and an mTOR inhibitor (rapamycin) attenuated ghrelin-caused colon cancer cell proliferation. We found that ghrelin induced time-dependent increases in Ras activity. Moreover, ghrelin-mediated Akt Ser473 phosphorylation was attenuated by a Ras DN and LY 294002. Furthermore, a Ras DN, LY 294002, and an Akt DN all inhibited ghrelin-caused mTOR Ser2448 phosphorylation. These results indicate that the Ras/PI3K/Akt/mTOR cascade plays a critical role in ghrelin-induced colon cancer cell proliferation.

Estrogen receptor α in cancer associated fibroblasts suppresses prostate cancer invasion via reducing CCL5, IL6 and macrophage infiltration in the tumor microenvironment

Background

Cancer associated fibroblasts (CAF) play important roles in tumor growth that involves inflammation and epithelial cell differentiation. Early studies suggested that estrogen receptor alpha (ERα) was expressed in stromal cells in normal prostates and prostate cancer (PCa), but the detailed functions of stromal ERα in the PCa remain to be further elucidated.

Methods

Migration and invasion assays demonstrated the presence of high levels of ERα in CAF cells (CAF.ERα(+)) suppressed PCa invasion via influencing the infiltration of tumor associated macrophages. ERα decreased CAF CCL5 secretion via suppressing the CCL5 promoter activity was examined by luciferase assay. ERα decreased CCL5 and IL-6 expression in conditioned media that was collected from CAF cell only or CAF cell co-cultured with macrophages as measured by ELISA assay.

Results

Both in vitro and in vivo studies demonstrated CAF.ERα(+) led to a reduced macrophage migration toward PCa via inhibiting CAF cells secreted chemokine CCL5. This CAF.ERα(+) suppressed macrophage infiltration affected the neighboring PCa cells invasion and the reduced invasiveness of PCa cells are at least partly due to reduced IL6 expression in the macrophages and CAF.

Conclusion

Our data suggest that CAF ERα could be applied as a prognostic marker to predict cancer progression, and targeting CCL5 and IL6 may be applied as an alternative therapeutic approach to reduce M2 type macrophages and PCa invasion in PCa patients with low or little ERα expression in CAF cells.

Electronic supplementary material

The online version of this article (doi:10.1186/s12943-015-0488-9) contains supplementary material, which is available to authorized users.

Vitamin D, Inflammation, and Colorectal Cancer Progression: A Review of Mechanistic Studies and Future Directions for Epidemiological Studies

Survival from colorectal cancer is positively associated with vitamin D status. However, whether this association is causal remains unclear. Inflammatory processes may link vitamin D to colorectal cancer survival, and therefore investigating inflammatory markers as potential mediators may be a valuable next step. This review starts with an overview of inflammatory processes suggested to be involved in colorectal cancer progression and regulated by vitamin D. Next, we provide recommendations on how to study inflammatory markers in future epidemiologic studies on vitamin D and colorectal cancer survival. Mechanistic studies have shown that calcitriol-active form of vitamin D-influences inflammatory processes involved in cancer progression, including the enzyme cyclooxygenase 2, the NF-κB pathway, and the expression of the cytokines TNFα, IL1β, IL6, IL8, IL17, and TGFβ1. Based on this and taking into account methodologic issues, we recommend to include analysis of specific soluble peptides and proteins, such as cytokines, in future epidemiologic studies on this issue. Vitamin D and the markers should preferably be measured at multiple time points during disease progression or recovery and analyzed using mediation analysis. Including these markers in epidemiologic studies may help answer whether inflammation mediates a causal relationship between vitamin D and colorectal cancer survival.

Curcumin Inhibits Invasiveness and Epithelial-Mesenchymal Transition in Oral Squamous Cell Carcinoma Through Reducing Matrix Metalloproteinase 2, 9 and Modulating p53-E-Cadherin Pathway

Hypotheses. Epithelial-mesenchymal transition (EMT) and invasion play a critical role in cancer progression and metastasis. We have shown that low E-cadherin and high Twist expression are significantly correlated with prognostic survival prediction in oral squamous cell carcinoma (OSCC). This study aimed to determine the anti-invasive effect of curcumin on the expression of matrix metalloproteinases (MMPs) and of EMT regulators in OSCC. Methods. SCC-25 cells were treated with curcumin, and cell proliferation, invasion, and expression of MMPs and EMT regulators were assessed for cell viability by trypan blue exclusion, for invasion by Matrigel invasion chamber, and for EMT regulators and MMP changes in the levels of proteins by immunoblotting. Results. Our data showed that curcumin treatment not only decreased the expression of MMP-2 and MMP-9 to inhibit invasiveness in oral cancer but also modulated the expression of EMT markers, such as Snail, Twist, and E-cadherin, and induced p53 expression that is crucial to EMT repression. Conclusion. Curcumin has the potential to become an adjunctive regimen for the prevention of cancer progression and metastasis in oral cancer.

Anti-proliferative action of IL-6R-targeted antibody tocilizumab for non-small cell lung cancer cells

In the present study we analyzed the anti-proliferative effect of tocilizumab, a humanized recombinant monoclonal interleukin 6 receptor (IL-6R) antibody, against non-small cell lung cancer (NSCLC) cells, including A549, H460, H358 and H1299 cells. The cell cycle distribution of NSCLCs was analyzed using fluorescence-activated cell sorting and gene expression using quantitative polymerase chain reaction. Cell lysates treated with tocilizumab were immunoblotted with antibodies against signal transducer and activator of transcription 3 (STAT3), phospho-STAT3, extracellular-signal-regulated kinases (ERK), phospho-ERK, nuclear factor κB (NFκB) and phospho-NFκB. Significant growth inhibition of NSCLC cells was observed following treatment with tocilizumab. Proliferation was significantly decreased by approximately 10-40% in A549, H460, H1299 and H358 cells, with an inhibition rate that was comparable with that of the typical anticancer drugs methotrexate and 5-fluorouracil. NSCLC cell populations were accumulated in the sub-G1 phase by treatment with tocilizumab. Western blot analyses revealed a possible activation of the NFκB pathway by tocilizumab. Overall, these data indicate that tocilizumab has anticancer potency via apoptosis induction as an agonistic IL-6R regulator. Therefore, we suggest that this anti-IL-6R antibody may be utilized as a new targeting molecule for NSCLC therapies.

Magnitude of influenza virus replication and cell damage is associated with interleukin-6 production in primary cultures of human tracheal epithelium

Primary cultures of human tracheal epithelium were infected with influenza viruses to examine the relationships between the magnitude of viral replication and infection-induced cell damage and cytokine production in airway epithelial cells. Infection with four strains of the type A influenza virus increased the detached cell number and lactate dehydrogenase (LDH) levels in the supernatants. The detached cell number and LDH levels were related to the viral titers and interleukin (IL)-6 levels and the nuclear factor kappa B (NF-κB) p65 activation. Treatment of the cells with an anti-IL-6 receptor antibody and an NF-κB inhibitor, caffeic acid phenethyl ester, reduced the detached cell number, viral titers and the LDH levels and improved cell viability after infection with the pandemic influenza virus [A/Sendai-H/N0633/2009 (H1N1) pdm09]. A caspase-3 inhibitor, benzyloxycarbonyl-DEVD-fluoromethyl ketone, reduced the detached cell number and viral titers. Influenza viral infection-induced cell damage may be partly related to the magnitude of viral replication, NF-κB-p65-mediated IL-6 production and caspase-3 activation.

Interleukin-6 promotes the migration and invasion of nasopharyngeal carcinoma cell lines and upregulates the expression of MMP-2 and MMP-9

Nasopharyngeal carcinoma (NPC) shows the highest invasive and metastatic features among head and neck cancers. Distant metastasis remains the predominant mode of treatment failure in NPC patients. The role of interleukin-6 (IL-6) in NPC progression is not fully understood. In this study, we explored whether IL-6 could promote the migration and invasion activity of NPC cell lines, as well as whether the effect of IL-6 on cell migration and invasion is mediated through regulating the expression of matrix metalloproteinase-2 (MMP-2) and MMP-9. Our results revealed that IL-6 and its receptors are broadly expressed in various NPC cell lines including HNE1, HONE1, CNE1, CNE1-LMP1 and 5-8F. Exogenous IL-6 enhanced cell proliferation slightly, but promoted cell migration and invasion significantly in both HNE1 and CNE1-LMP1 cell lines. In addition, an elevation in the expression of MMP-2 and MMP-9 could be induced by IL-6 stimulation. On the contrary, combining treatment with monoclonal anti-human IL-6R antibody (anti-IL-6R mAb) resulted in decreased proliferation, migration and invasion capabilities of NPC cells. Anti-IL-6R mAb also inhibited the expression of MMP-2 and MMP-9 in IL-6-stimulated HNE1 and CNE1-LMP1 cells. In summary, our data suggested that IL-6 mainly promotes the cell migration and invasion of NPC cells. The effect of IL-6 on cell migration and invasion may be mediated through regulation of the expression of MMP-2 and MMP-9. Thus, IL-6 or its related signaling pathways may be a promising target for preventing and inhibiting NPC metastasis.

Loss of suppressors of cytokine signaling 3 promotes aggressiveness in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common cancers with a high mortality rate. Constitutive activation of STAT3 is found in various types of tumors, including HCC. In addition, suppressors of cytokine signaling 3 (SOCS3) signals for negative feedback to STATs, and is found to be inversely correlated with STAT3 expression. However, the exact role of SOCS3 in the tumorigenesis and progression of HCC is not fully understood. In this study we intended to show that SOCS3 inhibition promotes proliferation, migration, and invasion of HCC cells. HepG2, a human HCC cell line, was grown with SOCS3 siRNA or negative control (NC) transfection to assess the involvement of SOCS3 in cell proliferation, migration, and invasion by MTT, migration, and invasion assays, respectively. Western blot analysis was performed to examine the expression of STAT3, SOCS3, c-myc, matrix metalloproteinase (MMP)-2, and MMP-9 after transfection with either SOCS3 or NC siRNAs. A diethylnitrosamine (DEN)-induced HCC mouse model was assessed with or without injection of NSC 74859, a STAT3 inhibitor, to show accompanied changes among the expressions of STAT3, SOCS3, c-myc, MMP-2, and MMP-9. Inhibition of SOCS3 expression promoted the proliferation, migration, and invasion of HepG2 cells and increased the expression of c-myc, MMP-2, and MMP-9. HCC tumors developed in mice by DEN-induction with administration of NSC 74859 resulted in decreased expression of c-myc, MMP-2, and MMP-9, but not SOCS3. Loss of SOCS3 increased tumor growth, migration, and invasion and resulted in accompanied changes in expression of STAT3 and its target oncoproteins.

Interleukin-6 released by colon cancer-associated fibroblasts is critical for tumour angiogenesis: anti-interleukin-6 receptor antibody suppressed angiogenesis and inhibited tumour-stroma interaction

Background:

Interleukin-6 (IL-6) has an important role in cancer progression, and high levels of plasma IL-6 are correlated with a poor prognosis in a variety of cancers. It has also been reported that tumour stromal fibroblasts are necessary for steps in cancer progression, such as angiogenesis. There have been few reports of a correlation between fibroblast actions and IL-6 levels. In this study, we examined the correlation between cancer stromal fibroblasts and IL-6 and the utility of IL-6 as a therapeutic target in human colon cancer.

Methods:

The expression levels of IL-6 and VEGF of fibroblasts and cancer cell lines were evaluated using real-time PCR and ELISA. The anti-angiogenic effect of inhibiting IL-6 signalling was measured in an angiogenesis model and animal experiment.

Results:

We demonstrate that stromal fibroblasts isolated from colon cancer produced significant amounts of IL-6 and that colon cancer cells enhanced IL-6 production by stromal fibroblasts. Moreover, IL-6 enhanced VEGF production by fibroblasts, thereby inducing angiogenesis. In vivo, anti-IL6 receptor antibody targeting stromal tissue showed greater anti-tumour activity than did anti-IL6 receptor antibody targeting xenografted cancer cells.

Conclusion:

Cancer stromal fibroblasts were an important source of IL-6 in colon cancer. IL-6 produced by activated fibroblasts induced tumour angiogenesis by stimulating adjacent stromal fibroblasts. The relationship between IL-6 and stromal fibroblasts offers new approaches to cancer therapy.

Novel drug discovery opportunities for colorectal cancer

INTRODUCTION

Colorectal cancer (CRC) is a leading cause of cancer mortality worldwide, with > 1.2 million new cases and > 600,000 deaths per year. This complex disease is driven by multiple genetic lesions, commonly dysregulated signaling pathways, and aberrant activity of developmental programs such as Notch and Wnt. While emerging therapies such as EGFR inhibitors are improving treatment regimens, recent findings elucidating the role of cancer stem cells provide insights into opportunities for novel therapeutic intervention.

AREAS COVERED

This review provides a background on CRC statistics, colon anatomy and CRC pathobiology, CRC genetics and current and emerging therapies. Furthermore, the article discusses the role of developmental signaling pathways governing self-renewal biology as potential points for therapeutic intervention.

EXPERT OPINION

Despite recent advances including the introduction of targeted therapeutics, prognosis for advanced CRC patients remains bleak, reinforcing the need for novel therapeutic intervention. Developmental pathways such as Notch and Wnt provide opportunities to address this urgent need, and preclinical evidence supports targeting these pathways in CRC. Progress has been made toward this end, and while challenges persist, an increasing number of preclinical findings show promise.

Both STAT1 and STAT3 are favourable prognostic determinants in colorectal carcinoma

BACKGROUND

Aberrant activities of Janus kinase (JAK)/signal transducer and activator of transcription (STAT) signalling pathways have been implicated in the development and spread of various cancer entities, among them colorectal carcinoma (CRC). Transcription factors STAT3 and STAT1, both downstream effectors of interleukin (IL)-6 and its receptor, are involved in growth and developmental control of CRC cells. Constituents of the signalling network around IL-6 and STAT activation are discussed as potential biomarkers and therapeutic targets in CRC.

METHODS

By immunohistochemical analysis of a tissue microarray covering >400 CRC biopsies, the expression and activity status of STAT1, STAT3 as well as of IL-6 and the IL-6 receptor α-chain was determined. The outcome was correlated with clinical information and patients' survival data. Colorectal carcinoma biopsies were also analysed for specific DNA-binding activity of STATs.

RESULTS

Statistical analysis showed tendential associations between individual STATs, IL-6/IL-6 receptor-α and clinicopathological parameters. The study revealed a significant correlation of high STAT1 activity with longer patient overall survival. Surprisingly, strong STAT3 expression in surgical specimens was correlated with an increase in median overall survival by about 30 months. Statistical analysis revealed that high expression levels of STAT1 and STAT3 were associated. This finding was backed up by biochemical data that showed simultaneous STAT1 and STAT3 DNA-binding activity in randomly selected CRC biopsies.

CONCLUSION

By multivariate data analysis, we could show that STAT3 expression and activity constitutes an independent favourable prognostic marker for CRC.

Colon cancer mesenchymal stem cells modulate the tumorigenicity of colon cancer through interleukin 6

Multipotent mesenchymal stem cells (MSCs) have been isolated from several tumors and are implicated to play critical roles to increase malignant cell growth, invasion and metastasis. Here, we show that the MSC-like cells were isolated from human colon cancer tissues. These isolated hCC-MSCs (human colon cancer-derived mesenchymal stem cells) shared similar characteristic features with bone marrow-derived MSCs, which include cell morphology, surface antigens and specific gene expression. Additionally, the hCC-MSCs could differentiate into osteocytes or adipocytes under appropriate culture conditions. The conditioned medium collected from the cultured hCC-MSCs was shown to enhance the migration and invasive activity of HCT-116 colon cancer cells in vitro. Besides, transplantation of HCT-116 cells along with hCC-MSCs in nude mice increased the tumor growth and metastasis. Further study revealed that IL-6 present in the hCC-MSC-conditioned medium sufficiently induced the levels of Notch-1 and CD44 in HCT-116 and HT-29 cells, which contribute to enhance tumorigenic activity of HCT-116 and HT-29 cells. By using immunohistochemical staining, the intense co-expression of IL-6, Notch-1 and CD44 was predominantly detected in human colon cancer tissues. Taken together, our findings suggest the importance of the IL-6/Notch-1/CD44 signaling axis in the interaction between hCC-MSCs and colon cancer cells.

Minocycline suppresses interleukine-6, its receptor system and signaling pathways and impairs migration, invasion and adhesion capacity of ovarian cancer cells: in vitro and in vivo studies

Interleukin (IL)-6 has been shown to be a major contributing factor in growth and progression of ovarian cancer. The cytokine exerts pro-tumorigenic activity through activation of several signaling pathways in particular signal transducer and activator of transcription (STAT3) and extracellular signal-regulated kinase (ERK)1/2. Hence, targeting IL-6 is becoming increasingly attractive as a treatment option in ovarian cancer. Here, we investigated the effects of minocycline on IL-6 and its signaling pathways in ovarian cancer. In vitro, minocycline was found to significantly suppress both constitutive and IL-1β or 4-hydroxyestradiol (4-OH-E2)-stimulated IL-6 expression in human ovarian cancer cells; OVCAR-3, SKOV-3 and CAOV-3. Moreover, minocycline down-regulated two major components of IL-6 receptor system (IL-6Rα and gp130) and blocked the activation of STAT3 and ERK1/2 pathways leading to suppression of the downstream product MCL-1. In female nude mice bearing intraperitoneal OVCAR-3 tumors, acute administration (4 and 24 h) of minocycline (30 mg/kg) led to suppression of IL-6. Even single dose of minocycline was effective at significantly lowering plasma and tumor IL-6 levels. In line with this, tumoral expression of p-STAT3, p-ERK1/2 and MCL-1 were decreased in minocycline-treated mice. Evaluation of the functional implication of minocycline on metastatic activity revealed the capacity of minocycline to inhibit cellular migration, invasion and adhesion associated with down-regulation of matrix metalloproteinases (MMP)-2 and 9. Thus, the data suggest a potential role for minocycline in suppressing IL-6 expression and activity. These effects may prove to be an important attribute to the upcoming clinical trials of minocycline in ovarian cancer.

Silibinin inhibits the invasion of IL-6-stimulated colon cancer cells via selective JNK/AP-1/MMP-2 modulation in vitro

Silibinin is a flavonoid with antihepatotoxic properties and pleiotropic anticancer capabilities. This study investigated silibinin inhibition of cell invasion by down-regulating matrix metalloproteinase-2 (MMP-2) expression, via attenuation of activator protein-1 (AP-1) in IL-6-stimulated LoVo colon cancer cells. Western blot data showed that the expression of MMP-2 protein was reduced 1.6- or 1.7-fold over the control by treatment with silibinin or JNK inhibitor in the models. Similar results were revealed in zymography and confocal microscopy. Pretreatment with silibinin also abolished the binding activity of AP-1 and MMP-2 promoter activity via AP-1 binding, as observed by EMSA and luciferase assay. Finally, a [(3)H]-thymidine incorporation proliferation assay and cell migration assay demonstrated that silibinin inhibited IL-6-stimulated LoVo cell proliferation and invasion. Taken together, these data indicated that silibinin inhibits LoVo cell invasion with the reduction of MMP-2 presentation by attenuating AP-1 binding activity, suggesting a novel antimetastatic application for silibinin in colon cancer chemoprevention.

MiRNA expression analysis of cancer-associated fibroblasts and normal fibroblasts in breast cancer

Cancer-associated fibroblasts (CAFs) promote tumorigenesis, growth, invasion and metastasis of cancer, whereas normal fibroblasts (NFs) are thought to suppress tumor progression. Little is known about miRNAs expression differences between CAFs and NFs or the patient-to-patient variability in miRNAs expression in breast cancer. We established primary cultures of CAFs and paired NFs from six resected breast tumor tissues that had not previously received radiotherapy or chemotherapy treatment and analyzed with miRNAs microarrays. The array data were analyzed using paired SAM t-test and filtered according to α and q values. Pathway analysis was conducted using DAVID v6.7. We identified 11 dysregulated miRNAs in CAFs: three were up-regulated (miR-221-5p, miR-31-3p, miR-221-3p), while eight were down-regulated (miR-205, miR-200b, miR-200c, miR-141, miR-101, miR-342-3p, let-7g, miR-26b). Their target genes are known to affect cell differentiation, adhesion, migration, proliferation, secretion and cell-cell interaction. By our knowledge it is firstly identify the expression profiles of miRNAs between CAFs and NFs and revealed their regulation on the associated signaling pathways.

The absence of Nrf2 enhances NF-κB-dependent inflammation following scratch injury in mouse primary cultured astrocytes

It has been proved that Nrf2 depletion enhances inflammatory process through activation of NF-κB in the brain after TBI, but little is known about the relationship between Nrf2 and NF-κB in astrocytes after TBI. Hence, we used primary cultured astrocytes from either Nrf2 wildtype or knockout mice to study the influence of Nrf2 on the activation of NF-κB and expression of proinflammatory cytokines in a model of TBI in vitro. Primary cultured astrocytes were scratched to mimic the traumatic injury in vitro. Then the DNA-binding activity of NF-κB was evaluated by EMSA. The mRNA and protein levels of TNF-α, IL-1β, IL-6, and MMP9 were also evaluated. Gelatin zymography was performed to detect the activity of MMP9. The activity of NF-κB and expression of proinflammatory cytokines mentioned above were upregulated at 24 h after scratch. The expression and activity of MMP9 were also elevated. And such tendency was much more prominent in Nrf2 KO astrocytes than that in WT astrocytes. These results suggest that the absence of Nrf2 may induce more aggressive inflammation through activation of NF-κB and downstream proinflammatory cytokines in astrocytes.

Role of MMP-2 in the regulation of IL-6/Stat3 survival signaling via interaction with α5β1 integrin in glioma

Matrix metalloproteinase-2 (MMP-2) has pivotal role in the degradation of extracellular matrix, and thereby enhances the invasive, proliferative and metastatic potential in cancer. Knockdown of MMP-2 using MMP-2 small interfering RNA (pM) in human glioma xenograft cell lines 4910 and 5310 decreased cell proliferation compared with mock and pSV (scrambled vector) treatments, as determined by 5-bromo-2'-deoxyuridine incorporation, Ki-67 staining and clonogenic survival assay. Cytokine array and western blotting using tumor-conditioned media displayed modulated secretory levels of various cytokines including granulocyte-macrophage colony-stimulating factor, interleukin-6 (IL-6), IL-8, IL-10, tumor necrosis factor-α, angiogenin, vascular endothelial growth factor and PDGF-BB in MMP-2 knockdown cells. Further, cDNA PCR array indicated potential negative regulation of Janus kinase/Stat3 pathway in pM-treated cells. Mechanistically, MMP-2 is involved in complex formation with α5 and β1 integrins and MMP-2 downregulation inhibited α5β1 integrin-mediated Stat3 phosphorylation and nuclear translocation. Electrophoretic mobility shift assay and chromatin immunoprecipitation assays showed inhibited Stat3 DNA-binding activity and recruitment at CyclinD1 and c-Myc promoters in pM-treated cells. In individual experiments, IL-6 or siRNA-insensitive MMP-2 overexpression by pM-FL-A141G counteracted and restored the pM-inhibited Stat3 DNA-binding activity, suggesting IL-6/Stat3 signaling suppression in pM-treated 4910 and 5310 cells. MMP-2/α5β1 binding is enhanced in human recombinant MMP-2 treatments, resulting in elevated Stat3 DNA-binding activity and recruitment on CyclinD1 and c-Myc promoters. Activation of α5β1 signaling by Fibronectin adhesion elevated pM-inhibited Stat3 phosphorylation whereas blocking α5β1 abrogated constitutive Stat3 activation. In vivo experiments with orthotropic tumor model revealed the decreased tumor size in pM treatment compared with mock or pSV treatments. Immunofluorescence studies in tumor sections corroborated our in vitro findings evidencing high expression and co-localization of MMP-2/α5β1, which is decreased upon pM treatment along with significantly reduced IL-6, phospho-Stat3, CyclinD1, c-Myc, Ki-67 and PCNA expression levels. Our data indicate the possible role of MMP-2/α5β1 interaction in the regulation of α5β1-mediated IL-6/Stat3 signaling activation and signifies the therapeutic potential of blocking MMP-2/α5β1 interaction in glioma treatment.

The colorectal tumor microenvironment: the next decade

Colorectal cancer cells establish a crosstalk with the tumor microenvironment, such that implantation and development of the tumor is generally favoured. CRC progression depends on mutations in the tumor's oncogenic pathways as well as metastasis suppressor genes, but is also influenced by the inflammatory components in the microenvironment. Inflammation results from the dietary intakes and is either compounded or counterbalanced by our lifestyles. Whether driven by intrinsic pathways or infection, inflammation produces a massive influx of cytokines and chemokines. Currently, in colorectal cancer, the best approach to counter this inflammatory wave in the microenvironment appears to be CCL2 cytokine targeting. A fairly new avenue of discovery has identified microRNAs regulating colorectal cancer-mediated inflammation, and in particular the IL-6 pro-inflammatory pathway that induces pro-apoptotic genes and HIF1α-elicited VEGF secretion. miRNAs also play a significant role in controlling metabolic genes such as the upregulation of the fatty acid synthase gene with the concomitant down-regulation of the carnitine palmitoyl transferase 1 gene. Within the metastatic environment, the Discoidin domain receptor-2 (DDR2) gene encodes a tyrosine kinase receptor for fibrillar collagen that contributes to colorectal cancer metastasis by increasing myofibroblasts, neoangiogenic vessels and proliferating cancer cells. Ongoing identification of gene signatures differentiating between primary tumor cells and their metastatic counterparts promises a wealth of new targets to be exploited for further therapeutic use within the next decade.