The Basement Membrane in a 3D Breast Acini Model Modulates Delivery and Anti-Proliferative Effects of Liposomal Anthracyclines

Breast cancer progression is marked by cancer cell invasion and infiltration, which can be closely linked to sites of tumor-connected basement membrane thinning, lesion, or infiltration. Bad treatment prognosis frequently accompanies lack of markers for targeted therapy, which brings traditional chemotherapy into play, despite its adverse effects like therapy-related toxicities. In the present work, we compared different liposomal formulations for the delivery of two anthracyclines, doxorubicin and aclacinomycin A, to a 2D cell culture and a 3D breast acini model. One formulation was the classical phospholipid liposome with a polyethylene glycol (PEG) layer serving as a stealth coating. The other formulation was fusogenic liposomes, a biocompatible, cationic, three-component system of liposomes able to fuse with the plasma membrane of target cells. For the lysosome entrapment-sensitive doxorubicin, membrane fusion enabled an increased anti-proliferative effect in 2D cell culture by circumventing the endocytic route. In the 3D breast acini model, this process was found to be limited to cells beneath a thinned or compromised basement membrane. In acini with compromised basement membrane, the encapsulation of doxorubicin in fusogenic liposomes increased the anti-proliferative effect of the drug in comparison to a formulation in PEGylated liposomes, while this effect was negligible in the presence of intact basement membranes.

Protease inhibition by Heterodera glycines cyst content: evidence for effects on the Meloidogyne incognita proteasome

Proteases from Heterodera glycines and Meloidogyne incognita juveniles were inhibited by heat-stable content from H. glycines cysts (hHglCE), and by a polyphenol (EGCG) similar to a compound previously identified in Globodera cysts. General protease activities detected using the nematode peptide KSAYMRFa were inhibited by EGCG (IC50 1.19 mM, H. glycines; 0.34 mM, M. incognita) but not by hHglCE. However, hHglCE and EGCG each inhibited proteasome-associated chymotrypsin-like (CT-L) activity. EGCG IC50 values were 0.47 mM (H. glycines) and 0.15 mM (M. incognita). hHglCE IC50 values were 0.16 and 0.005 mM hHglCEeq μl−1 for H. glycines and M. incognita, respectively. Across all substrate-inhibitor combinations, M. incognita proteases were inhibited more robustly than those from H. glycines, particularly by hHglCE. In addition to CT-L protease, post-glutamate peptide hydrolysing (PGPH) and trypsin-like (T-L) proteasome proteases were detected in M. incognita, and each of these was also strongly inhibited by hHglCE. hHglCE inhibited CT-L, PGPH and T-L proteases within catalytic subunits from yeast (Saccharomyces cerevisiae) and human proteasomes. Proteasome inhibitors MG-132 and aclacinomycin A each inhibited M. incognita CT-L and PGPH activities by more than 80% at 20-100 μM, and hHglCE inhibited the same proteases by 70-80% at 0.04 hHglCEeq μl−1. hHglCE completely inhibited M. incognita T-L activity, but CT-L activity in native content from H. glycines cysts was not inhibited. Evidence that H. glycines cysts contain inhibitors of all proteases associated with the proteasome establishes the cyst as an important new target to explore for potential nematode control compounds. In addition, characterisation of protease activities from a core cellular metabolic component using M. incognita is novel for plant-parasitic nematodes.

Low-Dose Arsenic Trioxide Combined with Aclacinomycin a Synergistically Enhance the Cytotoxic Effect on Human Acute Myelogenous Leukemia KG-1a Cell Line By the Induction of Apoptosis

Acute myeloid leukemia (AML) is a kind of common disorder in the elderly. Although remarkable progress has been made in the treatment of this deadly disease over the past few decades, the outcome remains poor. While conventional chemotherapy may be effective for some elderly patients, the vast majority do not tolerate intensive conventional treatment well, thus the development of a more effective method to overcome this problem is necessary. Aclacinomycin A (ACM), an antitumor antibiotic, was used to treat various tumors including AML. However, its high toxicity limits its clinical application. Previous studies reported that arsenic trioxide (As2O3) has shown substantial efficacy in treating patients suffering from AML. However, the molecular mechanisms of As2O3-induced cytotoxic effect of AML cells are not yet fully known. The aim of this study was to investigate the synergistic cytotoxic effect of low-dose As2O3 combined with ACM on human KG-1a cells and to clarify the possible mechanism underlying this combination treatment. Our results showed that As2O3 or ACM inhibited proliferation of KG-1a cells in a time- and dose-independent manner. In the flow cytometric analysis, the low-dose of the matched combination treatment induced a more prominent apoptosis than the single agent-treated groups. Furthermore, western blot analysis showed that the combination treatment decreased Bcl-2 expression and increased caspase-3 expression more significantly than the single drug treatments. More importantly, we showed that the combination index (CI) values were < 1 in all matched combination groups analyzed by compusyn software. In conclusion, our data showed that low-dose As2O3 combined with ACM showed a more prominent cytotoxic effect than single agent treatment on KG-1a cells. These results may provide a high efficiency but low-toxicity therapeutic benefits for AML. Disclosures No relevant conflicts of interest to declare.