Synergistic Effect of Gemcitabine and Clofazimine in Co-loaded Liposomal Formulation for Multidrug Treatment Approach of Osteosarcoma

ntroduction: Osteosarcoma is the most common cancer in bone with high occurrence in children. The development of resistance is a challenge of current treatment strategies that needs to be improved with novel treatment strategies. In the current research, a new dual drug delivery system was developed with Gemcitabine (GEM) and Clofazimine (CLF) co-loaded liposome formulations for osteosarcoma treatment. GEM is a pyrimidine antimetabolite that inhibits DNA synthesis and CLF is a leprostatic and anti-inflammatory drug that has been recently recognized as effective on cancer. Liposomal formulation of GEM and CLF was prepared using advantage of their specific localization in liposome; hydrophilic GEM being loaded into core and lipophilic CLF sequestering in hydrophobic lipid-bilayer. It is the first time that CLF is evaluated for its cytotoxicity on bone cancer cells and investigated for its synergistic effect with GEM on osteosarcoma. Methods: PEGylated liposomal formulations were prepared with DPPC:CHOL:DSPE-PEG (2000) lipids. They were investigated for their GEM and CLF encapsulation and loading efficiencies, in vitro release profiles, particle size, zeta potential and morphological properties. The cytotoxicity of liposome formulations were investigated by MTT assay on Saos-2 cells. Flow cytometry analyses were done to determine apoptotic effects of GEM, CLF and their co-loaded liposome groups on Saos-2 cells. Results: Characterization studies showed high encapsulation efficiency and loading of both GEM and CLF in liposome formulations. CLF release was enhanced while GEM release was slowed down in co-loaded formulations compared to their single loaded cases. Size of all liposomal formulations were under 200 nm and zeta potential values were slightly negative. All GEM/CLF co-loaded liposomal formulations showed significantly enhanced cytotoxicity than GEM loaded and CLF loaded liposome treatments. Use of CLF with GEM was found to have synergistic effect (CI<1) according to CompuSyn analysis. Results of flow cytometry experiments showed higher apoptotic cell ratio upon GEM/CLF co-loaded liposome treatments compared to other liposome treatment groups. Conclusion: Novel liposome formulation of GEM/CLF co-loaded liposome was successfully presented for the first time in this study. CLF’s single or co encapsulation with GEM into liposome was a new approach for enhancement of anticancer effect on Saos-2 cells. This formulation is thought to bring further advantages in terms of decreased side effects with the CLF contribution. It is also expected to provide specific therapeutic benefits of liposomal formulations. Therefore, GEM/CLF co-loaded liposomal delivery system is proposed to bring a novel approach for treatment of osteosarcoma

Structure-based design, synthesis and anticancer effect of cyclic Smac-polyarginine peptides

The second mitochondria-derived activator of caspase (Smac/DIABLO) is a pro-apoptotic protein that released from mitochondria into the cytosol when cells undergo apoptosis. Smac promotes caspase activation by binding the inhibitors of apoptosis proteins (IAP), particularly XIAP and eliminating their inhibitory activity. Although the seven N-terminal amino acids AVPIAQK (SmacN7) of Smac protein is able to elicit an anticancer response by itself, it is neither cell-permeable nor stable in the cellular environment. Thus, the use of SmacN7 derivatives and mimetics is an alluring field for cancer therapy. In this study, heptamer Smac peptide was fused to a well-known octaarginine cell-penetrating peptide for promoting its intracellular access. Both therapeutic Smac part and cell-penetrating octaarginine parts of the peptide sequence constrained in a cyclic structure so as to enhance the apoptosis-inducing potential of the SmacN7 peptide. Biological assays interestingly showed that cyclic peptides P4, P5 and P7 gave rise to a significant level of cytotoxicity and apoptosis mediated cell death in multiple myeloma tumor cells (MM) comparing to linear peptide

Peptidomic Characterization and Bioactivity of Protoiurus Kraepelini (Scorpiones: Iuridae) Venom

Protoiurus kraepelini is a scorpion species found in parts of Turkey and Greece. In this study, the peptide profile of its venom was determined for the first time. The electrophoretic profile of the crude venom showed a protein distribution from 2 to 130 kDa. MALDI-TOF MS analysis of the venom peptide fraction yielded 27 peptides between 1059 and 4623 Da in mass. Several ion channelblocking and antimicrobial peptides were identified by peptide mass fingerprinting analysis. Cytotoxic and antimicrobial effects of the venom were also demonstrated on Jurkat cells and Escherichia coli, respectively. As the first peptidomic characterization study on P. kraepelini venom, this report lays the foundation for detailed future studies that may lead to the discovery of novel bioactive peptides.PubMedWoSScopu