Metabolic shift toward oxidative phosphorylation in docetaxel resistant prostate cancer cells

Drug resistance of cancer cells is recognized as the primary cause of failure of chemotherapeutic treatment in most human cancers. Growing evidences support the idea that deregulated cellular metabolism is linked to such resistance. Indeed, both components of the glycolytic and mitochondrial pathways are involved in altered metabolism linked to chemoresistance of several cancers. Here we investigated the drug-induced metabolic adaptations able to confer advantages to docetaxel resistant prostate cancer (PCa) cells. We found that docetaxel-resistant PC3 cells (PC3-DR) acquire a pro-invasive behavior undergoing epithelial-to-mesenchymal-transition (EMT) and a decrease of both intracellular ROS and cell growth. Metabolic analyses revealed that PC3-DR cells have a more efficient respiratory phenotype than sensitive cells, involving utilization of glucose, glutamine and lactate by the mitochondrial oxidative phosphorylation (OXPHOS). Consequently, targeting mitochondrial complex I by metformin administration, impairs proliferation and invasiveness of PC3-DR cells without effects on parental cells. Furthermore, stromal fibroblasts, which cause a "reverse Warburg" phenotype in PCa cells, reduce docetaxel toxicity in both sensitive and resistant PCa cells. However, re-expression of miR-205, a microRNA strongly down-regulated in EMT and associated to docetaxel resistance, is able to shift OXPHOS to a Warburg metabolism, thereby resulting in an elevated docetaxel toxicity in PCa cells. Taken together, these findings suggest that resistance to docetaxel induces a shift from Warburg to OXPHOS, mandatory for conferring a survival advantage to resistant cells, suggesting that impairing such metabolic reprogramming could be a successful therapeutic approach.Associazione Italiana Ricerca sul Cancro (AIRC), Istituto Toscano Tumori and Regione Toscan

Cellular response to empty and palladium-conjugated amino-polystyrene nanospheres uptake: A proteomic study

Amino polystyrene nanospheres are shown to be efficient and controllable delivery devices, capable of transporting several bioactive cargoes. Recently, the design of a new device for prodrug activation, using these nanospheres with palladium encapsulated onto them, has been developed successfully. To study the influence of the cellular uptake of these nanodevices, we investigated the cellular response of human embryonic kidney cells (HEK-293T) and murine fibroblasts (L929) treated with empty or palladium-conjugated amino polystyrene nanospheres. To identify differentially expressed proteins, we performed an exhaustive proteomic analysis. In accordance with genomic data previously obtained, the uptake of the empty nanospheres did not induce significant variation in protein expression levels. Following the treatment with palladium-conjugated nanospheres, some changes in protein profiles in both cell lines were observed; these alterations affect proteins involved in cell metabolism and intracellular transport. No key regulator of the cell cycle result was differentially expressed after the treatment, confirming that these innovative drug delivery systems are harmless and well tolerated by the cells

Cellular response to empty and palladium-conjugated amino-polystyrene nanospheres uptake: A proteomic study

Amino polystyrene nanospheres are shown to be efficient and controllable delivery devices, capable of transporting several bioactive cargoes. Recently, the design of a new device for prodrug activation, using these nanospheres with palladium encapsulated onto them, has been developed successfully. To study the influence of the cellular uptake of these nanodevices, we investigated the cellular response of human embryonic kidney cells (HEK-293T) and murine fibroblasts (L929) treated with empty or palladium-conjugated amino polystyrene nanospheres. To identify differentially expressed proteins, we performed an exhaustive proteomic analysis. In accordance with genomic data previously obtained, the uptake of the empty nanospheres did not induce significant variation in protein expression levels. Following the treatment with palladium-conjugated nanospheres, some changes in protein profiles in both cell lines were observed; these alterations affect proteins involved in cell metabolism and intracellular transport. No key regulator of the cell cycle result was differentially expressed after the treatment, confirming that these innovative drug delivery systems are harmless and well tolerated by the cells

Bone marrow‐derived mesenchymal stem cells promote invasiveness and transendothelial migration of osteosarcoma cells via a mesenchymal to amoeboid transition

There is growing evidence to suggest that bone marrow‐derived mesenchymal stem cells (BM‐MSCs) are key players in tumour stroma. Here, we investigated the cross‐talk between BM‐MSCs and osteosarcoma (OS) cells. We revealed a strong tropism of BM‐MSCs towards these tumour cells and identified monocyte chemoattractant protein (MCP)‐1, growth‐regulated oncogene (GRO)‐α and transforming growth factor (TGF)‐β1 as pivotal factors for BM‐MSC chemotaxis. Once in contact with OS cells, BM‐MSCs trans‐differentiate into cancer‐associated fibroblasts, further increasing MCP‐1, GRO‐α, interleukin (IL)‐6 and IL‐8 levels in the tumour microenvironment. These cytokines promote mesenchymal to amoeboid transition (MAT), driven by activation of the small GTPase RhoA, in OS cells, as illustrated by the in vitro assay and live imaging. The outcome is a significant increase of aggressiveness in OS cells in terms of motility, invasiveness and transendothelial migration. In keeping with their enhanced transendothelial migration abilities, OS cells stimulated by BM‐MSCs also sustain migration, invasion and formation of the in vitro capillary network of endothelial cells. Thus, BM‐MSC recruitment to the OS site and the consequent cytokine‐induced MAT are crucial events in OS malignancy

Lipid peroxidation in Soleus and EDL muscles.

<p>Lipid peroxidation was evaluated by measuring the malondialdehyde levels. Black bars: control animals; gray bars: ASE animals. Two-tailed, non- paired Student’s t-test was performed. * indicates a p-value <0.05.</p

Representative Oxyblot and silver stained gels of Soleus muscle from control and ASE animals.

<p>Muscle proteins from control (A) and ASE animals (B) were separated by IEF and carbonylated proteins were derivatized with DNPH in the strip (18 cm, 3–10 NL). Second dimension was performed in 9–16% polyacrylamide linear gradient. In panel C and D the corresponding silver stained gels are shown. Circles indicate spots where carbonylation was affected by ASE. Circles and numbers indicate spots identified by MS.</p

Identity of Soleus and EDL muscle proteins whose carbonylation is affected by acute swimming.

a<p>Spot numbers match those reported in the representative 2-DE images shown in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0071839#pone-0071839-g002" target="_blank">Fig. 2</a> (Soleus muscle) and in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0071839#pone-0071839-g003" target="_blank">Fig. 3</a> (EDL muscle).</p>b<p>Accession number in UniProtKB/Swiss-Prot.</p>c<p>Fold change control <i>vs.</i> ASE was calculated as follow: %V_control/%V_ASE. (<i>p</i><0.05).</p

Representative Oxyblot and silver stained gels of EDL muscle from control and ASE animals.

<p>Muscle proteins from control (A) and ASE animals (B) were separated by IEF and carbonylated proteins were derivatized with DNPH in the strip (18 cm, 3–10 NL). Second dimension was performed in 9–16% polyacrylamide linear gradient. In panel C and D the corresponding silver stained gels are shown. Circles indicate spots where carbonylation was affected by ASE. Circles and numbers indicate spots identified by MS.</p