Intracellular target delivery of cell-penetrating peptide-conjugated dodecaborate for boron neutron capture therapy (BNCT).

In this study, we designed and synthesized organelle-targeted cell-penetrating peptide (CPP)-conjugated boron compounds to increase their cellular uptake and to control the intracellular locations for the induction of sophisticated anticancer biological activity in boron neutron capture therapy (BNCT), leading to anticancer effects with ATP reduction and apoptosis when irradiated with neutrons in an in vitro BNCT assay.

Effects of gefitinib treatment on cellular uptake of extracellular vesicles in EGFR-mutant non-small cell lung cancer cells.

Extracellular vesicles (exosomes, EVs) are cell membrane particles (30-200 nm) secreted by virtually all cells. During intercellular communication in the body, secreted EVs play crucial roles by carrying functional biomolecules (e.g., microRNAs and enzymes) into other cells to affect cellular function, including disease progression. We previously reported that the macropinocytosis pathway contributes greatly to the efficient cellular uptake of EVs. The activation of growth factor receptors, such as epidermal growth factor receptor (EGFR), induces macropinocytosis. In this study, we demonstrated the effects of gefitinib, a tyrosine kinase inhibitor of EGFR, on the cellular uptake of EVs. In EGFR-mutant HCC827 non-small cell lung cancer (NSCLC) cells, which are sensitive to gefitinib, macropinocytosis was suppressed by gefitinib treatment. However, the cellular uptake of EVs was increased by gefitinib treatment, whereas that of liposomes was reduced. In accordance with the results of the cellular uptake studies, the anti-cancer activity of doxorubicin (DOX)-loaded EVs in HCC827 cells was significantly increased in the presence of gefitinib, whereas the activity of DOX-loaded liposomes was reduced. The digestion of EV proteins by trypsin did not affect uptake, suggesting that the cellular uptake of EVs might not be mediated by EV proteins. These results suggest that gefitinib can enhance cell-to-cell communication via EVs within the tumor microenvironment. In addition, EVs show potential as drug delivery vehicles in combination with gefitinib for the treatment of patients harboring EGFR-mutant NSCLC tumors.

Plant Ribosome-Inactivating Proteins: Progesses, Challenges and Biotechnological Applications (and a Few Digressions).

Plant ribosome-inactivating protein (RIP) toxins are EC3.2.2.22 N-glycosidases, found among most plant species encoded as small gene families, distributed in several tissues being endowed with defensive functions against fungal or viral infections. The two main plant RIP classes include type I (monomeric) and type II (dimeric) as the prototype ricin holotoxin from Ricinus communis that is composed of a catalytic active A chain linked via a disulphide bridge to a B-lectin domain that mediates efficient endocytosis in eukaryotic cells. Plant RIPs can recognize a universally conserved stem-loop, known as the α-sarcin/ ricin loop or SRL structure in 23S/25S/28S rRNA. By depurinating a single adenine (A4324 in 28S rat rRNA), they can irreversibly arrest protein translation and trigger cell death in the intoxicated mammalian cell. Besides their useful application as potential weapons against infected/tumor cells, ricin was also used in bio-terroristic attacks and, as such, constitutes a major concern. In this review, we aim to summarize past studies and more recent progresses made studying plant RIPs and discuss successful approaches that might help overcoming some of the bottlenecks encountered during the development of their biomedical applications.

Gefitinib Enhances Mitochondrial Biological Functions in NSCLCs with EGFR Mutations at a High Cell Density.

BACKGROUND/AIM: Gefitinib is a tyrosine kinase inhibitor of epidermal growth factor receptor (EGFR) and has been approved for the treatment of non-small cell lung cancers (NSCLCs) with EGFR mutations. Here we demonstrated that gefitinib induced a significantly enhanced biological activity of succinate-tetrazolium reductase (STR) in mitochondria and mitochondrial membrane potential in HCC827 cells (EGFR mutation NSCLCs, sensitive to gefitinib) at a high cell density. MATERIALS AND METHODS: We assessed the biological activity (STR, mitochondrial membrane potential, expression level of Bcl-2 family proteins) of gefitinib on NSCLCs at different cell densities. RESULTS: The 3D cell culture experiments showed the enhanced mitochondrial biological activity in clustered cell culture treated with gefitinib. Interestingly, the expression levels of Bcl-xL and Bax, were affected by the cellular number and gefitinib treatment. We also found that gefitinib prevented additive anticancer activity in the combinational treatment with doxorubicin, which induces mitochondria-dependent apoptotic cell death. CONCLUSION: Our results indicate that gefitinib may work as a mitochondrial protector against combinational treatment with mitochondria-dependent anticancer agents in high-cell-density.