Mohammad Hossein Pourgholami

Tetracyclines: drugs with huge therapeutic potential.

Tetracyclines are an amazing class of chemical agents with multiple therapeutic potential. Structural modification of the original natural tetracyclines led to the synthesis and development of doxycycline and minocycline, compounds with higher lipophilicity, better oral pharmacokinetics and higher potency. Due to diverse pharmacological properties, these drugs are now under extensive investigation for use in the treatment of various disparate diseases. In recent years, several studies have conclusively reported anti-inflammatory, immune-modulating and neuroprotective effects of these compounds. There are currently over 200 ongoing clinical trials on tetracyclines. These studies extend over a wide range of diseases including dermatological diseases, behavior and mental disorders, immune system disorders, cardiovascular diseases, and cancer. In this review we will discuss the chemistry and pharmacology of these agents, and describe how their inhibitory effect on matrix metalloproteinase and on pro-inflammatory cytokines has kindled renewed interest in them. Based on the reports from pre-clinical and clinical trials, the therapeutic potential and application of tetracyclines may well be redefined and extensively extended.

Gene of the month: Interleukin 6 (IL-6).

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 Critical Role of Vascular Endothelial Growth Factor in Tumor Angiogenesis

Angiogenesis is the formation of new blood vessels from the pre-existing vasculature. Besides its role in normal physiology, angiogenesis is significantly involved in many pathological conditions, including inflammation, cardiovascular diseases and cancer. Numerous studies have been undertaken in the area of tumor angiogenesis. It is known that pathological angiogenesis is necessary for tumors to proceed from avascular, dormant stage to vascular, sprouting stage and also contributes to their later invasion and metastasis. Playing a central role in tumor angiogenesis, vascular endothelial growth factor is considered as a key target in therapeutic approaches. This article aims to review the critical role of VEGF in tumor angiogenesis and the importance of VEGF-targeted strategies in cancer treatment.

Minocycline Targets the NF-κB Nexus through Suppression of TGF-β1-TAK1-IκB Signaling in Ovarian Cancer

Substantial evidence supports the critical role of NF-κB 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-κB transcriptome. Here, it was examined whether or not the molecular mechanism could be attributed to modulation of NF-κB signaling using a combination of in vitro and in vivo models. Minocycline suppressed constitutive NF-κB activation in OVCAR-3 and SKOV-3 ovarian carcinoma cells and was correlated with attenuation of IκBα kinase (IKK) activation, IκBα phosphorylation and degradation, and p65 phosphorylation and nuclear translocation. The inhibition of IKK was found to be associated with suppression of TGF-β-activated-kinase-1 (TAK1) activation and its dissociation from TAK1-binding-protein-1 (TAB1), an indispensable functional mediator between TGF-β and TAK1. Further studies demonstrated that minocycline downregulated TGF-β1 expression. Enforced TGF-β1 expression induced NF-κB activity, and minocycline rescued this effect. Consistent with this finding, TGF-β1 knockdown suppressed NF-κB activation and abrogated the inhibitory effect of minocycline on this transcription factor. These results suggest that the minocycline-induced suppression of NF-κB activity is mediated, in part, through inhibition of TGF-β1. Furthermore, the influence of minocycline on NF-κB 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-κB 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-β—NF-κB axis in ovarian cancer. Implications: This preclinical study lends support to the notion that ovarian cancer management would benefit from administration of minocycline. Mol Cancer Res; 11(10); 1279–91. ©2013 AACR.

p70 Ribosomal protein S6 kinase (Rps6kb1): an update.

The Rps6kb1 gene encodes the 70u2005kDa 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.

Abstract 3689: Minocycline regulates hypoxia-inducible factor-1α expression through the induction of its degradation in ovarian cancer: in vitro and in vivo studies

Proceedings: AACR Annual Meeting 2014; April 5-9, 2014; San Diego, CAnnExperimental data suggest therapeutic advantage from selective disruption of the hypoxia response in cancer. We recently found that minocycline decreases tumor VEGF expression in ovarian tumor xenografts in mice and herein report a companion laboratory study to test if this effect was the result of hypoxia-inducible factor (HIF) inhibition. Human ovarian carcinoma cell lines (OVCAR-3, SKOV-3 and A2780) were treated with minocycline in normoxic and hypoxic conditions and also in the presence of hypoxia-mimetic agent deferoxamine in vitro. Two different in vivo experiments investigated miocycline effects after single dose (30 mg/kg, 4 or 24 h) or longer exposure in nude mice bearing OVCAR-3 xenografts. Treatment with minocycline inhibited the accumulation of HIF-1alpha in a concentration-dependent fashion in vitro. A similar effect of minocycline was seen in vivo. Furthermore, the inhibtory effect of minocycline on HIF-1alpha was found to be associated with a significant decrease in HIF-1alpha half-life showing that minocycline enhances degradtion of HIF-1alpha. These data warrents further evaluation of minocycline in the treatment of ovarian cancer.nnCitation Format: Parvin Ataie-Kachoie, David L. Morris, Mohammad H. Pourgholami. Minocycline regulates hypoxia-inducible factor-1α expression through the induction of its degradation in ovarian cancer: in vitro and in vivo studies. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3689. doi:10.1158/1538-7445.AM2014-3689

Abstract A7: Minocycline regulates Hypoxia-Inducible Factor-1α expression through the induction of its degradation in ovarian cancer: in vitro and in vivo studies.

Experimental data suggest therapeutic advantage from selective disruption of the hypoxia response in cancer. We recently found that minocycline decreases tumor VEGF expression in ovarian tumor xenografts in mice and herein report a companion laboratory study to test if this effect was the result of hypoxia-inducible factor (HIF) inhibition. Human ovarian carcinoma cell lines (OVCAR-3, SKOV-3 and A2780) were treated with minocycline in normoxic and hypoxic conditions and also in the presence of hypoxia-mimetic agent deferoxamine in vitro. Two different in vivo experiments investigated miocycline effects after single dose (30 mg/kg, 4 or 24 h) or longer exposure in nude mice bearing OVCAR-3 xenografts. Treatment with minocycline inhibited the accumulation of HIF-1alpha in a concentration-dependent fashion in vitro. A similar effect of minocycline was seen in vivo. Furthermore, the inhibtory effect of minocycline on HIF-1alpha was found to be associated with a significant decrease in HIF-1alpha half-life showing that minocycline enhances degradtion of HIF-1alpha. These data warrents further evaluation of minocycline in the treatment of ovarian cancer.nnCitation Information: Mol Cancer Ther 2013;12(11 Suppl):A7.nnCitation Format: Parvin Ataie-Kachoie, Mohammad H. Pourgholami, David L. Morris. Minocycline regulates Hypoxia-Inducible Factor-1α expression through the induction of its degradation in ovarian cancer: in vitro and in vivo studies. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr A7.