bafilomycin-a1 and Neoplasms

Damage-associated molecular pattern molecules (DAMPs) are endogenous danger signals that alert the innate immune system and shape the inflammation response to cell death. However, the release and activity of DAMPs in ferroptosis, a recently identified form of regulated necrosis characterized by iron overload and lipid peroxidation, still remain poorly understood. Here, we demonstrate that HMGB1 is a DAMP released by ferroptotic cells in an autophagy-dependent manner. Both type I and II ferroptosis activators, including erastin, sorafenib, RSL3, and FIN56, induce HMGB1 release in cancer and noncancer cells. In contrast, genetic ablation (using ATG5

Topics: Animals; Autophagy; Carbolines; Cell Death; Cell Line, Tumor; Chloroquine; Ferritins; Fibroblasts; HMGB1 Protein; Humans; Immunity, Innate; Inflammation; Iron Overload; Lipid Peroxidation; Macrolides; Mice; Neoplasms; Oximes; Piperazines; Sorafenib; Sulfonamides; Toll-Like Receptor 4

Several grafted polypropylenimine dendrimers were synthesized by modifying either polypropylenimine (PPI) dendrimer generation 2 (G2) or generation 3 (G3) via 1.6-hexandioldiacrylate with branched oligoethylenimine 800Da (OEI) or PPI dendrimer G2. The resulting derivatives were characterized ((1)H NMR, GPC) and their biophysical properties such as DNA condensing ability, colloidal stability and hydrodynamic diameters were determined. All grafted dendrimers were able to efficiently compact DNA to nanosized polyplexes (100-200 nm) and exhibited an increased colloidal stability as compared to their unmodified counterparts. In vitro, grafted dendrimers resulted in much higher transfection levels as compared to the unmodified ones displaying alongside a clear structure-activity relationship regarding their transfection/toxicity profile. Transfection levels of OEI-grafted dendrimers were the highest, being similar or even higher as compared to standard polyethylenimines (linear and branched), demonstrating that the incorporation of ethylenimine moieties is the key factor contributing to this boosted transfection efficiency. None of the compounds resulted in polymer-induced erythrocyte aggregation. Upon i.v. injection of OEI-grafted dendrimer polyplexes into tumor-bearing mice transgene expression was predominantly found in the (subcutaneous) tumors. Importantly, the tumor gene expression levels significantly increased with the higher dendrimer core generation.

Topics: Animals; Cell Line, Tumor; Cell Survival; Dendrimers; Electricity; Erythrocytes; Ethidium; Gene Expression; Gene Transfer Techniques; Hemolysis; Luciferases, Firefly; Macrolides; Male; Mice; Mice, Inbred Strains; Neoplasms; Particle Size; Plasmids; Polyethyleneimine; Polypropylenes; Proton Pump Inhibitors; Saline Solution, Hypertonic; Transfection

Although Akt is known as a survival kinase, inhibitors of the phosphatidylinositol 3-kinase (PI3K)-Akt pathway do not always induce substantial apoptosis. We show that silencing Akt1 alone, or any combination of Akt isoforms, can suppress the growth of tumors established from phosphatase and tensin homologue-null human cancer cells. Although these findings indicate that Akt is essential for tumor maintenance, most tumors eventually rebound. Akt knockdown or inactivation with small molecule inhibitors did not induce significant apoptosis but rather markedly increased autophagy. Further treatment with the lysosomotropic agent chloroquine caused accumulation of abnormal autophagolysosomes and reactive oxygen species, leading to accelerated cell death in vitro and complete tumor remission in vivo. Cell death was also promoted when Akt inhibition was combined with the vacuolar H(+)-adenosine triphosphatase inhibitor bafilomycin A1 or with cathepsin inhibition. These results suggest that blocking lysosomal degradation can be detrimental to cancer cell survival when autophagy is activated, providing rationale for a new therapeutic approach to enhancing the anticancer efficacy of PI3K-Akt pathway inhibition.

Topics: Animals; Apoptosis; Autophagy; Autophagy-Related Protein 7; Benzylamines; Cell Cycle; Cell Line, Tumor; Chloroquine; Drug Interactions; Female; Furans; Humans; Lysosomes; Macrolides; Mice; Mice, Nude; Mitochondria; Mutation; Neoplasms; Phosphoinositide-3 Kinase Inhibitors; Proto-Oncogene Proteins c-akt; Proton-Translocating ATPases; PTEN Phosphohydrolase; Pyridines; Pyrimidines; Quinoxalines; Reactive Oxygen Species; RNA Interference; RNA, Small Interfering; Ubiquitin-Activating Enzymes; Xenograft Model Antitumor Assays

The aim was to determine if a specific inhibitor of vacuolar H(+)-ATPases (V-ATPases), Bafilomycin A1 (BFM), could increase the low extracellular pH (pHe) typical of solid tumours and thus inhibit their growth in vivo. BFM inhibited the proliferation of various human cells and rat pituitary GH3 tumour cells in vitro (IC50: 2.5-19.2 nM), and flow cytometry on GH3 cells showed a marked increase in S and G2M phases after 16-48 h, but no evidence of increased apoptosis. BFM caused significant inhibition of GH3 xenograft growth, and histomorphometry showed a 30% decrease in mitosis but no change in apoptosis. 31P-magnetic resonance spectroscopy (MRS) in vivo of GH3 xenografts showed that BFM increased pHe, but did not affect pHi, resulting in a decrease in the negative pH gradient (-delta pH). BFM decreased lactate formation suggesting a reduction in glycolysis. We suggest that BFM reduces extracellular H(+)-transport by inhibition of V-ATPases leading to an increase in pHe and decreased glycolysis, and thus reduced tumour cell proliferation. 19F-MRS in vivo showed that a smaller -delta pH was associated with decreased retention of 5-fluorouracil (5FU) which was consistent with our previous data in vivo implying the -delta pH controls tumour retention of 5 FU.

Topics: Animals; Anti-Bacterial Agents; Antifungal Agents; Antimetabolites, Antineoplastic; Cell Division; Fluorouracil; Hydrogen-Ion Concentration; Macrolides; Mice; Mice, Nude; Mitosis; Neoplasm Transplantation; Neoplasms; Rats; Rats, Wistar; Transplantation, Heterologous; Tumor Cells, Cultured