A lectin mediated delivery system for the intravesical treatment of bladder diseases using poly-(L)-glutamic acid as polymeric backbone.

In this study, we present a targeted drug delivery system to improve intravesical therapy of bladder diseases. The drug delivery system consists of wheat germ agglutinin (WGA) to facilitate specific interaction with the surface of bladder cells and α-poly-(L)-glutamic acid (PGA) as polymeric backbone to increase the number of drug molecules per targeting moiety. Additionally, fluorescein cadaverine was coupled to PGA to visualise and track the delivery system. Using 5637 single cells and cell monolayers, the optimised F-PGA-WGA delivery system, with an approximate molecular weight of 670kDa, could convince with its promising cytoadhesive as well as cytoinvasive potential. Using the competitive inhibitor N, N', N″-triacetylchitotriose a specificity of the carbohydrate-mediated interaction between the cell and the delivery system of up to 98% was determined. F-PGA alone did not show any interaction with the cells. Moreover, a high drug loading of 77 molecules of the model drug Dansylcadaverine per backbone was achieved. Microscopic analysis further confirmed binding and uptake of the cytoadhesive polymer even after additional loading with the model drug. Combining the auspicious targeting properties of WGA with the high drug loading possibilities of the backbone might finally lead to an enhanced efficacy when used for intravesical therapy.

Vitamin D analog EB1089 triggers dramatic lysosomal changes and Beclin 1-mediated autophagic cell death.

A chemotherapeutic vitamin D analogue, EB1089, kills tumor cells via a caspase-independent pathway that results in chromatin condensation and DNA fragmentation. Employing transmission- and immunoelectronmicroscopy as well as detection of autophagosome-associated LC3-beta protein in the vacuolar structures, we show here that EB1089 also induces massive autophagy in MCF-7 cells. Interestingly, inhibition of autophagy effectively hindered apoptosis-like nuclear changes and cell death in response to EB1089. Furthermore, restoration of normal levels of beclin 1, an autophagy-inducing tumor suppressor gene that is monoallelically deleted in MCF-7 cells, greatly enhanced the EB1089-induced nuclear changes and cell death. Thus, EB1089 triggers nuclear apoptosis via a pathway involving Beclin 1-dependent autophagy. Surprisingly, tumor cells depleted for Beclin 1 failed to proliferate suggesting that even though the monoallelic depletion of beclin 1 in human cancer cells suppresses EB1089-induced autophagic death, one intact beclin 1 allele is essential for tumor cell proliferation.