Extracellular Heat Shock Protein (Hsp)70 and Hsp90α Assist in Matrix Metalloproteinase-2 Activation and Breast Cancer Cell Migration and Invasion

Breast cancer is second only to lung cancer in cancer-related deaths in women, and the majority of these deaths are caused by metastases. Obtaining a better understanding of migration and invasion, two early steps in metastasis, is critical for the development of treatments that inhibit breast cancer metastasis. In a functional proteomic screen for proteins required for invasion, extracellular heat shock protein 90 alpha (Hsp90α) was identified and shown to activate matrix metalloproteinase 2 (MMP-2). The mechanism of MMP-2 activation by Hsp90α is unknown. Intracellular Hsp90α commonly functions with a complex of co-chaperones, leading to our hypothesis that Hsp90α functions similarly outside of the cell. In this study, we show that a complex of co-chaperones outside of breast cancer cells assists Hsp90α mediated activation of MMP-2. We demonstrate that the co-chaperones Hsp70, Hop, Hsp40, and p23 are present outside of breast cancer cells and co-immunoprecipitate with Hsp90α in vitro and in breast cancer conditioned media. These co-chaperones also increase the association of Hsp90α and MMP-2 in vitro. This co-chaperone complex enhances Hsp90α-mediated activation of MMP-2 in vitro, while inhibition of Hsp70 in conditioned media reduces this activation and decreases cancer cell migration and invasion. Together, these findings support a model in which MMP-2 activation by an extracellular co-chaperone complex mediated by Hsp90α increases breast cancer cell migration and invasion. Our studies provide insight into a novel pathway for MMP-2 activation and suggest Hsp70 as an additional extracellular target for anti-metastatic drug development

Lipid Alterations in Experimental Murine Colitis: Role of Ceramide and Imipramine for Matrix Metalloproteinase-1 Expression

BACKGROUND:Dietary lipids or pharmacologic modulation of lipid metabolism are potential therapeutic strategies in inflammatory bowel disease (IBD). Therefore, we analysed alterations of bioactive lipids in experimental models of colitis and examined the functional consequence of the second messenger ceramide in inflammatory pathways leading to tissue destruction. METHODOLOGY/PRINCIPAL FINDINGS:Chronic colitis was induced by dextran-sulphate-sodium (DSS) or transfer of CD4(+)CD62L(+) cells into RAG1(-/-)-mice. Lipid content of isolated murine intestinal epithelial cells (IEC) was analysed by tandem mass spectrometry. Concentrations of MMP-1 in supernatants of Caco-2-IEC and human intestinal fibroblasts from patients with ulcerative colitis were determined by ELISA. Imipramine was used for pharmacologic inhibition of acid sphingomyelinase (ASM). Ceramide increased by 71% in chronic DSS-induced colitis and by 159% in the transfer model of colitis. Lysophosphatidylcholine (LPC) decreased by 22% in both models. No changes were detected for phosphatidylcholine. Generation of ceramide by exogenous SMase increased MMP-1-protein production of Caco-2-IEC up to 7-fold. Inhibition of ASM completely abolished the induction of MMP-1 by TNF or IL-1beta in Caco-2-IEC and human intestinal fibroblasts. CONCLUSIONS/SIGNIFICANCE:Mucosal inflammation leads to accumulation of ceramide and decrease of LPC in the intestinal epithelium. One aspect of ceramide generation is an increase of MMP-1. Induction of MMP-1 by TNF or IL-1beta is completely blocked by inhibition of ASM with imipramine. Therefore, inhibition of ASM may offer a treatment strategy to reduce MMP-1 expression and tissue destruction in inflammatory conditions

Do Stress Responses Promote Leukemia Progression? An Animal Study Suggesting a Role for Epinephrine and Prostaglandin-E2 through Reduced NK Activity

In leukemia patients, stress and anxiety were suggested to predict poorer prognosis. Oncological patients experience ample physiological and psychological stress, potentially leading to increased secretion of stress factors, including epinephrine, corticosteroids, and prostaglandins. Here we tested whether environmental stress and these stress factors impact survival of leukemia-challenged rats, and studied mediating mechanisms. F344 rats were administered with a miniscule dose of 60 CRNK-16 leukemia cells, and were subjected to intermittent forced swim stress or to administration of physiologically relevant doses of epinephrine, prostaglandin-E2 or corticosterone. Stress and each stress factor, and/or their combinations, doubled mortality rates when acutely applied simultaneously with, or two or six days after tumor challenge. Acute administration of the β-adrenergic blocker nadolol diminished the effects of environmental stress, without affecting baseline survival rates. Prolonged β-adrenergic blockade or COX inhibition (using etodolac) also increased baseline survival rates, possibly by blocking tumor-related or normal levels of catecholamines and prostaglandins. Searching for mediating mechanisms, we found that each of the stress factors transiently suppressed NK activity against CRNK-16 and YAC-1 lines on a per NK basis. In contrast, the direct effects of stress factors on CRNK-16 proliferation, vitality, and VEGF secretion could not explain or even contradicted the in vivo survival findings. Overall, it seems that environmental stress, epinephrine, and prostaglandins promote leukemia progression in rats, potentially through suppressing cell mediated immunity. Thus, patients with hematological malignancies, which often exhibit diminished NK activity, may benefit from extended β-blockade and COX inhibition

Inhibition of cancer cell invasion and metastasis by genistein

Genistein is a small, biologically active flavonoid that is found in high amounts in soy. This important compound possesses a wide variety of biological activities, but it is best known for its ability to inhibit cancer progression. In particular, genistein has emerged as an important inhibitor of cancer metastasis. Consumption of genistein in the diet has been linked to decreased rates of metastatic cancer in a number of population-based studies. Extensive investigations have been performed to determine the molecular mechanisms underlying genistein’s antimetastatic activity, with results indicating that this small molecule has significant inhibitory activity at nearly every step of the metastatic cascade. Reports have demonstrated that, at high concentrations, genistein can inhibit several proteins involved with primary tumor growth and apoptosis, including the cyclin class of cell cycle regulators and the Akt family of proteins. At lower concentrations that are similar to those achieved through dietary consumption, genistein can inhibit the prometastatic processes of cancer cell detachment, migration, and invasion through a variety of mechanisms, including the transforming growth factor (TGF)-β signaling pathway. Several in vitro findings have been corroborated in both in vivo animal studies and in early-phase human clinical trials, demonstrating that genistein can both inhibit human cancer metastasis and also modulate markers of metastatic potential in humans, respectively. Herein, we discuss the variety of mechanisms by which genistein regulates individual steps of the metastatic cascade and highlight the potential of this natural product as a promising therapeutic inhibitor of metastasis