What lurks beneath: IL-11, via Stat3, promotes inflammation-associated gastric tumorigenesis

Contribution of interaction between genetic variants of interleukin-11 and Helicobacter pylori infection to the susceptibility of gastric cancer

Background

Gastric cancer (GC) ranks the second leading cause of cancer-related mortality worldwide. We aimed to clarify the relevance of genetic variants of IL-11, a hub of various carcinogenic pathways, as well as their interactions with Helicobacter pylori (H. pylori) infection in the development of GC.

Methods

A case-control study with 880 GC cases and 900 healthy controls was conducted in a Chinese population. Six tagSNPs were detected by Taqman Allelic Discrimination assay, while H. pylori status was detected by Typing Detection Kit for Antibody to H. pylori and serum IL-11 level was measured using ELISA method.

Results

We found that rs1126760 (C vs T: OR=1.39, 95% CIs=1.13-1.70, P=0.002) and rs1126757 (C vs T: OR=0.82, 95% CIs=0.72-0.93, P=0.002) were significantly associated with susceptibility of GC. Even adjusted for Bonferroni correction, the results were still significant (P=0.002×6=0.012). IL-11 rs1126760 was significantly associated with higher serum and expression level of IL-11, while rs1126757 was significantly associated with lower serum IL-11 level (P<0.001). Significant interaction with H. pylori infection was identified for rs1126760 (P for interaction =0.005). Higher expression of the IL-11 gene was significant with development and poor prognosis of GC.

Conclusion

Our study provides strong evidence that genetic variants of the IL-11 gene may interact with H. pylori infection and contribute to the development of GC. Further studies with larger sample size and functional experiments are needed to validate our findings.

From inflammation to gastric cancer - the importance of Hedgehog/GLI signaling in Helicobacter pylori-induced chronic inflammatory and neoplastic diseases

Infections with the human pathogen Helicobacter pylori (H. pylori) are closely associated with the development of inflammatory disorders and neoplastic transformation of the gastric epithelium. Drastic changes in the micromilieu involve a complex network of H. pylori-regulated signal transduction pathways leading to the release of proinflammatory cytokines, gut hormones and a wide range of signaling molecules. Besides controlling embryonic development, the Hedgehog/GLI signaling pathway also plays important roles in epithelial proliferation, differentiation, and regeneration of the gastric physiology, but also in the induction and progression of inflammation and neoplastic transformation in H. pylori infections. Here, we summarize recent findings of H. pylori-associated Hedgehog/GLI signaling in gastric homeostasis, malignant development and the modulation of the gastric tumor microenvironment.

Helicobacter pylori infection and gastric carcinoma: Not all the strains and patients are alike

Gastric carcinoma (GC) develops in only 1%-3% of Helicobacter pylori (H. pylori) infected people. The role in GC formation of the bacterial genotypes, gene polymorphisms and host's factors may therefore be important. The risk of GC is enhanced when individuals are infected by strains expressing the oncoprotein CagA, in particular if CagA has a high number of repeats containing the EPIYA sequence in its C'-terminal variable region or particular amino acid sequences flank the EPIYA motifs. H. pylori infection triggers an inflammatory response characterised by an increased secretion of some chemokines by immunocytes and colonised gastric epithelial cells; these molecules are especially constituted by proteins composing the interleukin-1beta (IL-1β) group and tumour necrosis factor-alpha (TNF-α). Polymorphisms in the promoter regions of genes encoding these molecules, could account for high concentrations of IL-1β and TNF-α in the gastric mucosa, which may cause hypochlorhydria and eventually GC. Inconsistent results have been attained with other haplotypes of inflammatory and anti-inflammatory cytokines. Genomic mechanisms of GC development are mainly based on chromosomal or microsatellite instability (MSI) and deregulation of signalling transduction pathways. H. pylori infection may induce DNA instability and breaks of double-strand DNA in gastric mucocytes. Different H. pylori strains seem to differently increase the risk of cancer development run by the host. Certain H. pylori genotypes (such as the cagA positive) induce high degrees of chronic inflammation and determine an increase of mutagenesis rate, oxidative-stress, mismatch repair mechanisms, down-regulation of base excision and genetic instability, as well as generation of reactive oxygen species that modulate apoptosis; these phenomena may end to trigger or concur to GC development.

Clinicopathological and prognostic significance of IL-11 and Survivin overexpression in gastric cancer

AIM: To investigate the differential expression of interleukin-11 (IL-11) and Survivin in gastric cancer (GC) to understand their possible roles in carcinogenesis, progression and prognosis.

METHODS: Paraffin-embedded samples were obtained from 59 GC patients who underwent surgical operations at the First Affiliated Hospital of Shihezi University School of Medicine, Shihezi, China, between January 1, 2004 and December 31, 2007. All of the patients were followed to April 1, 20014. The expression of IL-11 and Survivin was detected using tissue chip and immunohistochemistry.

RESULTS: The positive expression rate of IL-11 was 96.6% in GC tissues, significantly higher than that in adjacent normal tissues (88.1%; χ² = 7.252, (P = 0.025). The positive expression rate of Survivin in GC tissues was also significantly higher than that in adjacent normal tissues (93.2% vs 72.9%, χ² = 41.988, P < 0.001). In GC tissues, there was a positive correlation between IL-11 and Survivin expression (r = 0.442, P < 0.001), but no correlation was found in adjacent normal tissues (r = 0.103, (P = 0.438). The expression of IL-11 was correlated with higher clinical stage ((P = 0.002), while Survivin expression was correlated with lymph node metastasis and higher clinical stage ((P = 0.002, 0.028). Higher levels of IL-11 and Survivin were linked to poor prognosis in GC patients ((P = 0.004 and P < 0.001, respectively). Cox multi-factorial regression analysis demonstrated clinical stage being an independent factor predicting overall survival of GC patients ((P = 0.017).

CONCLUSION: Overexpression of IL-11 and Survivin correlates with poor prognosis of GC patients, and they may play a coordinated role in the development, progression and prognosis of GC.

Autoimmunity as a double agent in tumor killing and cancer promotion

Cancer immunotherapy through manipulation of the immune system holds great potential for the treatment of human cancers. However, recent trials targeting the negative immune regulators cytotoxic T-lymphocyte antigen 4, programed death 1 (PD-1), and PD-1 receptor ligand (PD-L1) demonstrated that clinically significant antitumor responses were often associated with the induction of autoimmune toxicity. This finding suggests that the same immune mechanisms that elicit autoimmunity may also contribute to the destruction of tumors. Given the fact that the immunological identity of tumors might be largely an immunoprivileged self, autoimmunity may not represent a wholly undesirable outcome in the context of cancer immunotherapy. Rather, targeted killing of cancer cells and autoimmune damage to healthy tissues may be intricately linked through molecular mechanisms, in particular inflammatory cytokine signaling. On the other hand, since chronic inflammation is a well-recognized condition that promotes tumor development, it appears that autoimmunity can be a "double agent" in mediating either pro-tumor or antitumor effects. This review surveys the tumor-promoting and tumoricidal activities of several prominent cytokines: IFN-γ, TNF-α, TGF-β, IL-17, IL-23, IL-4, and IL-13, produced by three major subsets of T helper cells that interact with innate immune cells. Many of these cytokines exert divergent and seemingly contradictory effects on cancer development in different human and animal models, suggesting a high degree of context dependence in their functions. We hypothesize that these inflammatory cytokines could mediate a feedback loop of autoimmunity, antitumor immunity, and tumorigenesis. Understanding the diverse and paradoxical roles of cytokines from autoimmune responses in the setting of cancer will advance the long-term goal of improving cancer immunotherapy, while minimizing the hazards of immune-mediated tissue damage and the possibility of de novo tumorigenesis, through proper monitoring and preventive measures.

Genetic aspects of gastric cancer instability

Unravelling the molecular mechanisms underlying gastric carcinogenesis is one of the major challenges in cancer genomics. Gastric cancer is a very complex and heterogeneous disease, and although much has been learned about the different genetic changes that eventually lead to its development, the detailed mechanisms still remain unclear. Malignant transformation of gastric cells is the consequence of a multistep process involving different genetic and epigenetic changes in numerous genes in combination with host genetic background and environmental factors. The majority of gastric adenocarcinomas are characterized by genetic instability, either microsatellite instability (MSI) or chromosomal instability (CIN). It is believed that chromosome destabilizations occur early in tumour progression. This review summarizes the most common genetic alterations leading to instability in sporadic gastric cancers and its consequences.

Interleukin-11 promotes the progress of gastric carcinoma via abnormally expressed versican

Versican, a ubiquitous component of the extracellular matrix (ECM), accumulates both in tumor stroma and cancer cells and is highly regulated by various cytokines. The aberrant expression of versican and its isoforms is known to modulate cell proliferation, differentiation, and migration, all of which are features of the invasion and metastasis of cancer; versican is also known to favour the homeostasis of the ECM. Interleukin-11 (IL-11) is an important cytokine that exhibits a wide variety of biological effects in gastric cancer development. Here, we analysed the expression of versican isoforms and found that the major isoforms expressed by both gastric carcinoma tissue and gastric cell lines were V0 and V1, and V1 was significantly higher in gastric carcinoma tissue. The treatment of the gastric cell lines AGS and MKN45 with rhIL-11 resulted in a significant increase in the expression of V0 and V1. Exogenous IL-11 increased migration in AGS and MKN45 cells, whereas these effects were reversed when the expression of V0 and V1 were abolished by siRNA targeting versican V0/V1. Collectively, these findings suggest that the abnormally expressed versican and its isoforms participate, at least in part, in the progress of gastric carcinoma triggered by IL-11.

Glioma cell migration on three-dimensional nanofiber scaffolds is regulated by substrate topography and abolished by inhibition of STAT3 signaling

A hallmark of malignant gliomas is their ability to disperse through neural tissue, leading to long-term failure of all known therapies. Identifying new antimigratory targets could reduce glioma recurrence and improve therapeutic efficacy, but screens based on conventional migration assays are hampered by the limited ability of these assays to reproduce native cell motility. Here, we have analyzed the motility, gene expression, and sensitivity to migration inhibitors of glioma cells cultured on scaffolds formed by submicron-sized fibers (nanofibers) mimicking the neural topography. Glioma cells cultured on aligned nanofiber scaffolds reproduced the elongated morphology of cells migrating in white matter tissue and were highly sensitive to myosin II inhibition but only moderately affected by stress fiber disruption. In contrast, the same cells displayed a flat morphology and opposite sensitivity to myosin II and actin inhibition when cultured on conventional tissue culture polystyrene. Gene expression analysis indicated a correlation between migration on aligned nanofibers and increased STAT3 signaling, a known driver of glioma progression. Accordingly, cell migration out of glioblastoma-derived neurospheres and tumor explants was reduced by STAT3 inhibitors at subtoxic concentrations. Remarkably, these inhibitors were ineffective when tested at the same concentrations in a conventional two-dimensional migration assay. We conclude that migration of glioma cells is regulated by topographical cues that affect cell adhesion and gene expression. Cell migration analysis using nanofiber scaffolds could be used to reproduce native mechanisms of migration and to identify antimigratory strategies not disclosed by other in vitro models.

Smad4 deficiency in T cells leads to the Th17-associated development of premalignant gastroduodenal lesions in mice

While there is evidence that specific T cell populations can promote the growth of established tumors, instances where T cell activity causes neoplasms to arise de novo are infrequent. Here, we employed two conditional mutagenesis systems to delete the TGF-β signaling pathway component Smad4 in T cells and observed the spontaneous development of massive polyps within the gastroduodenal regions of mice. The epithelial lesions contained increased levels of transcripts encoding IL-11, IL-6, TGF-β, IL-1β, and TNF-α, and lamina propria cells isolated from lesions contained abundant IL-17A+CD4+ T cells. Furthermore, we found that Smad4 deficiency attenuated TGF-β-mediated in vitro polarization of FoxP3+CD4+ T cells, but not IL-17A+CD4+ T cells, suggesting that the epithelial lesions may have arisen as a consequence of unchecked Th17 cell activity. Proinflammatory cytokine production likely accounted for the raised levels of IL-11, a cytokine known to promote gastric epithelial cell survival and hyperplasia. Consistent with IL-11 having a pathogenic role in this model, we found evidence of Stat3 activation in the gastric polyps. Thus, our data indicate that a chronic increase in gut Th17 cell activity can be associated with the development of premalignant lesions of the gastroduodenal region.

Expression of anion exchanger 1 is associated with tumor progress in human gastric cancer

PURPOSE

Anion exchanger 1 (AE1) is a transmembrane glycoprotein which is abundantly expressed in erythrocyte plasma membrane and mediates the electroneutral exchange of Cl(-) and HCO(3) (-). We previously reported that the AE1 protein was unexpectedly expressed in the gastric and colonic cancer and take part in the carcinogenesis of the cancer cells. The aim of the present study is to determine the potential clinical implications of AE1 expression in gastric carcinoma.

METHODS

Immunohistochemistry assay was used to determine the expression of AE1 protein. The expression of AE1 in normal and malignant tissues from 286 patients with early and advanced gastric carcinoma was examined. The correlations of AE1 expression with clinicopathological parameters, including age, tumor size, location and subtypes, expression frequency, survival period and lymph metastasis were assessed by Chi-squared test and t test analysis.

RESULTS

AE1 immunoreactivity was negative in normal gastric tissue. Positive immunostaining of AE1 was detected in gastric carcinoma regardless of the location. AE1 was most frequently expressed in the gastric antrum carcinoma compared with gastric body cancer (P = 0.034). Expression of AE1 was significantly associated with bigger tumor size, deeper invasion, shorter survival period, and non-lymph metastasis. In para-cancer tissues of intestinal-type gastric cancer, the expression frequency of AE1 was higher than that in diffuse-type (P = 0.011).

CONCLUSION

The results showed a strong association of AE1 expression with the onset and progression of the gastric cancer and that may be helpful for improving the tumor classification and the treatment of cancer.

Hepatitis C virus core protein augments androgen receptor-mediated signaling

Hepatitis C virus (HCV) infection is frequently associated with the development of hepatocellular carcinoma (HCC), which is one of the male-dominant diseases. Androgen signaling in liver may be related to carcinogenesis. In this study, we investigated whether HCV proteins cross talk with the androgen receptor (AR) signaling pathway for promotion of carcinogenesis. We have demonstrated that HCV core protein alone or in context with other HCV proteins enhances AR-mediated transcriptional activity and further augments in the presence of androgen. Subsequent study suggested that HCV core protein activates STAT3, which in turn enhances AR-mediated transcription. This activity was blocked by a pharmacological inhibitor of the Jak/Stat signaling pathway, AG490. Vascular endothelial growth factor (VEGF) is a target gene of AR in liver and plays an important role in angiogenesis. Therefore, we examined whether HCV infection modulates VEGF expression in hepatocytes. Our results demonstrated that HCV enhances VEGF expression and facilitates tube formation in human coronary microvascular endothelial cells in the presence of AR. Together, our results suggest that HCV core protein acts as a positive regulator in AR signaling, providing further insight into oncogenic potential in the development of HCC in HCV-infected individuals.