The targeting effect of H_7K(R_2)_2-modified pH-sensitive liposomes on U87-MG cells

The present study aimed to investigate the targeting effect of H7K（R2）2-modified pH -sensitive liposomes on U87-MG cells. Using coumarin-6 as a fluorescence probe, we prepared H7K（R2）2-modified p H-sensitive liposomes（designated as coumarin-6-PSL-H7K（R2）2）. The flow cytometry assay was used to evaluate the effect of H7K（R2）2 proportions on the cellular uptake and endocytosis pathways of coumarin--6--PSL--H7K（R2）2 on U87-MG cells. The circular dichroism（CD） spectroscopy assay was used to investigate the secondary structures of H7K（R2）2 peptide at pH 7.4 and H 6.8, respectively. Our results indicated that the 2.5% proportion of H7K（R2）2 in the coumarin-6--PSL-H7K（R2）2 was superior to those of 1% and 3.5% of H7K（R2）2. The uptake of coumarin--6-PSL--H7K（R2）2 on U87--MG cells was not inhibited by filipin, M-β--CD or chlorpromazine. The secondary structure of H7K（R2）2 at pH 6.8 was mostly presented as β--turn. In conclusion, we suggested that the appropriate proportion of H7K（R2）2 in the H7K（R2）2--modified pH--sensitive liposomes could be set at 2.5%. The cellular uptake pathway for H7K（R2）2-modified pH--sensitive liposomes was via the cell penetrating capacity of H7K（R2）2 which responded to acidic condition. The secondary structure of H7K（R2）2 at pH 6.8, which was presented as the shape of hairpin, might be mainly responsible for its targeting and cell penetrating effect.

Efficacy of the new therapeutic approach in curing malignant neoplasms on the model of human glioblastoma

Objective:Glioma is a highly invasive tumor,frequently disposed in essential areas of the brain,which makes its surgical excision extremely difficult;meanwhile adjuvant therapy remains quite ineffective.Methods:In the current report,a new therapeutic approach in curing malignant neoplasms has been performed on the U87 human glioblastoma model.This approach,termed"Karanahan",is aimed at the eradication of cancer stem cells(CSCs),which were recently shown to be capable of internalizing fragments of extracellular double-stranded DNA.After being internalized,these fragments interfere in the process of repairing interstrand cross-links caused by exposure to appropriate cytostatics,and such an interference results either in elimination of CSCs or in the loss of their tumorigenic potency.Implementation of the approach requires a scheduled administration of cytostatic and complex composite double-stranded DNA preparation.Results:U87 cells treated in vitro in accordance with the Karanahan approach completely lost their tumorigenicity and produced no grafts upon intracerebral transplantation into immunodeficient mice.In SCID mice with developed subcutaneous grafts,the treatment resulted in reliable slowing down of tumor growth rate(P<0.05).In the experiment with intracerebral transplantation of U87 cells followed by surgical excision of the developed graft and subsequent therapeutic treatment,the Karanahan approach was shown to reliably slow down the tumor growth rate and increase the median survival of the mice twofold relative to the control.Conclusions:The effectiveness of the Karanahan approach has been demonstrated both in vitro and in vivo in treating developed subcutaneous grafts as well as orthotopic grafts after surgical excision of the tumor.