No abstract

The Interleukin 6 (IL-6) gene encodes the classic proinflammatory cytokine IL-6. It is also known as interferon-β2 (IFN-β2), B cell stimulatory factor-2 and hybridoma/plasmacytoma growth factor. IL-6 is a multifunctional cytokine with a central role in many physiological inflammatory and immunological processes. Due to its major role in initiation as well as resolving inflammation, deregulation of IL-6 is a mainstay of chronic inflammatory and autoimmune diseases. Additionally, IL-6 has been shown to be implicated in pathogenesis of many human malignancies. Thus, a better understanding of IL-6 and its role in various pathological conditions could enable the development of strategies to use it as a therapeutic target. This short review focuses on the structure, regulation and biological activities of IL-6. In addition we discuss the role of IL-6 in diseases with inflammatory background and cancer and also the therapeutic applications of anti-IL-6 agents.

The Rps6kb1 gene encodes the 70 kDa ribosomal protein S6 kinase (p70S6K), which is a serine/threonine kinase regulated by phosphoinositide 3-kinase (PI3K)/mammalian target of rapamycin (mTOR) pathway. p70S6K plays a crucial role in controlling cell cycle, growth and survival. The PI3K/mTOR signalling pathway is one of the major mechanisms for controlling cell survival, proliferation and metabolism and is the central regulator of translation of some components of protein synthesis system. Upon activation, this kinase phosphorylates S6 protein of ribosomal subunit 40S resulting in selective translation of unique family of mRNAs that contain oligopyrimidine tract on 5' transcriptional site (5'TOP). 5'TOP mRNAs are coding the components of translational apparatus including ribosomal proteins and elongation factors. Due to the role of p70S6K in protein synthesis and also its involvement in a variety of human diseases ranging from diabetes and obesity to cancer, p70S6K is now being considered as a new therapeutic target for drug development. Furthermore, p70S6K acts as a biomarker for response to immunosuppressant as well as anticancer effects of inhibitors of the mTOR. Because of the narrow therapeutic index of mTOR inhibitors, drug monitoring is essential, and this is usually done by measuring blood drug levels, therapeutic response and drug-induced adverse effects. Recent studies have suggested that plasma p70S6K is a reliable index for the monitoring of patient response to mTOR inhibitors. Therefore, a better understanding of p70S6K and its role in various pathological conditions could enable the development of strategies to aid diagnosis, prognosis and treatment schedules.

Substantial evidence supports the critical role of NF-kB in ovarian cancer. Minocycline, a tetracycline, has been shown to exhibit beneficial effects in this malignancy through regulation of a cohort of genes that overlap significantly with the NF-kB transcriptome. Here, it was examined whether or not the molecular mechanism could be attributed to modulation of NF-kB signaling using a combination of in vitro and in vivo models. Minocycline suppressed constitutive NF-kB activation in OVCAR-3 and SKOV-3 ovarian carcinoma cells and was correlated with attenuation of IkBa kinase (IKK) activation, IkBa phosphorylation and degradation, and p65 phosphorylation and nuclear translocation. The inhibition of IKK was found to be associated with suppression of TGF-b-activated-kinase-1 (TAK1) activation and its dissociation from TAK1-binding-protein-1 (TAB1), an indispensable functional mediator between TGF-b and TAK1. Further studies demonstrated that minocycline downregulated TGF-b1 expression. Enforced TGF-b1 expression induced NF-kB activity, and minocycline rescued this effect. Consistent with this finding, TGF-b1 knockdown suppressed NF-kB activation and abrogated the inhibitory effect of minocycline on this transcription factor. These results suggest that the minocycline-induced suppression of NF-kB activity is mediated, in part, through inhibition of TGF-b1. Furthermore, the influence of minocycline on NF-kB pathway activation was examined in female nude mice harboring intraperitoneal OVCAR-3 tumors. Both acute and chronic administration of minocycline led to suppression of p65 phosphorylation and nuclear translocation accompanied by downregulation of NF-kB activity and endogenous protein levels of its target gene products. These data reveal the therapeutic potential of minocycline as an agent targeting the pro-oncogenic TGF-b-NF-kB axis in ovarian cancer.