Interleukin 6 (IL-6), a well-known pro-inflammatory cytokine with pleiotropic activity is a central player in chronic inflammatory diseases including cancers. Therefore, blockade of the IL-6 signalling pathway has become a target for the therapy of diverse cancers such as multicentric Castleman's disease (CD), multiple myeloma and solid tumours including renal, prostate, lung, colorectal and ovarian cancers. Monoclonal antibodies against IL-6 (Siltuximab) and the IL-6 receptor (IL-6R) (Tocilizumab) have emerged as potential immunotherapies, alone or in combination with conventional chemotherapy. Human trials have demonstrated the ability to block IL-6 activity and in multicentric CD lead to durable clinical response and longer disease stabilisation. However, the efficacy of these treatments is still debatable for other cancers. New generation therapeutics in development such as Clazakizumab, Sarilumab, and soluble gp130-Fc have the additional features of improved binding affinity, better specificity with reduced adverse effects. A deeper understanding of the immunological basis of these agents, as well as of the challenges that are faced by immunotherapy-based products in clinical trials, will help select the most promising anti-IL-6/IL-6R therapies for large scale use. Concurrently, current research efforts to personalize treatments may help in the treatment of patients that would greatly benefit from IL-6 blocking therapies.
Interleukin-6 (IL-6) signaling network has been implicated in oncogenic transformations making it attractive target for the discovery of novel cancer therapeutics. In this study, potent antiproliferative and apoptotic effect of diacerein were observed against breast cancer. In vitro apoptosis was induced by this drug in breast cancer cells as verified by increased sub-G1 population, LIVE/DEAD assay, cell cytotoxicity and presence of terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL)-positive cells, as well as downregulation of antiapoptotic proteins Bcl-2 and Bcl-xL and upregulation of apoptotic protein Bax. In addition, apoptosis induction was found to be caspase dependent. Further molecular investigations indicated that diacerein instigated apoptosis was associated with inhibition of IL-6/IL-6R autocrine signaling axis. Suppression of STAT3, MAPK and Akt pathways were also observed as a consequence of diacerein-mediated upstream inhibition of IL-6/IL-6R. Fluorescence study and western blot analysis revealed cytosolic accumulation of STAT3 in diacerein-treated cells. The docking study showed diacerein/IL-6R interaction that was further validated by competitive binding assay and isothermal titration calorimetry. Most interestingly, it was found that diacerein considerably suppressed tumor growth in MDA-MB-231 xenograft model. The in vivo antitumor effect was correlated with decreased proliferation (Ki-67), increased apoptosis (TUNEL) and inhibition of IL-6/IL-6R-mediated STAT3, MAPK and Akt pathway in tumor remnants. Taken together, diacerein offered a novel blueprint for cancer therapy by hampering IL-6/IL-6R/STAT3/MAPK/Akt network.
Glioblastoma (GBM) is a highly fatal disease with a 5 year survival rate of less than 22%. One of the most effective treatment regimens to date is the use of radiotherapy which induces lethal DNA double-strand breaks to prevent tumour growth. However, recurrence occurs in the majority of patients and is in-part a result of robust radioresistance mechanisms. In this study, we demonstrate that the multifunctional cytokine, interleukin-6 (IL-6), confers a growth advantage in GBM cells but does not have the same effect on normal neural progenitor cells. Further analysis showed IL-6 can promote radioresistance in GBM cells when exposed to ionising radiation. Ablation of the Ataxia-telangiectasia mutated serine/threonine kinase that is recruited and activated by DNA double-strand breaks reverses the effect of radioresistance and re-sensitised GBM to DNA damage thus leading to increase cell death. Our finding suggests targeting the signaling cascade of DNA damage response is a potential therapeutic approach to circumvent IL-6 from promoting radioresistance in GBM.