salinomycin and Pancreatic-Neoplasms

Recently, salinomycin (SAL) has been reported to inhibit proliferation and induce apoptosis in various tumors. The aim of this study was to deliver SAL to orthotopic model of pancreatic cancer by the aid of poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NPs).. The NPs were physico-chemically characterized and evaluated for cytotoxicity on luciferase-transduced AsPC-1 cells in vitro as well as implanted orthotopically into the pancreas of nude mice.. SAL (3.5 mg/kg every other day) blocked tumor growth by 52% compared to the control group after 3 weeks of therapy. Western blotting of tumor protein extracts indicated that SAL treatment leads to up-regulation of E-cadherin, β-catenin, and transforming growth factor beta receptor (TGFβR) expressions in AsPC-1 orthotopic tumor. Noteworthy, immunofluorescence staining of adjacent tumor sections showed that treatment with SAL NPs cause significant apoptosis in the tumor cells rather than the stroma. Further investigations also revealed that TGFβR2 over-expression was induced in stroma cells after treatment with SAL NPs.. These results highlight SAL-loaded PLGA NPs as a promising system for pancreatic cancer treatment, while the mechanistic questions need to be subsequently tested.

Topics: Animals; Apoptosis; beta Catenin; Cadherins; Cell Line, Tumor; Cell Proliferation; Female; Humans; Lactic Acid; Mice; Mice, Nude; Nanoparticles; Pancreatic Neoplasms; Polyglycolic Acid; Polylactic Acid-Polyglycolic Acid Copolymer; Pyrans; Receptors, Transforming Growth Factor beta; Tumor Microenvironment; Xenograft Model Antitumor Assays

Pancreatic ductal adenocarcinoma (PDAC) is characterized by aggressive growth, early metastasis and high resistance to chemotherapy. Salinomycin is a promising compound eliminating cancer stem cells and retarding cancer cell migration. The present study investigated the effectiveness of salinomycin against PDAC in vivo and elucidated the mechanism of PDAC growth inhibition. Salinomycin treatment was well tolerated by the mice and significantly reduced tumor growth after 19 days compared to the control group (each n = 16). There was a trend that salinomycin also impeded metastatic spread to the liver and peritoneum. Whereas salinomycin moderately induced apoptosis and retarded proliferation at 5-10 µM, it strongly inhibited cancer cell migration that was accompanied by a marked loss of actin stress fibers after 6-9 h. Salinomycin silenced RhoA activity, and loss of stress fibers could be reversed by Rho activation. Moreover, salinomycin dislocated fascin from filopodia and stimulated Rac-associated circular dorsal ruffle formation. In conclusion, salinomycin is an effective and promising compound against PDAC. Besides its known stem cell-specific cytotoxic effects, salinomycin blocks cancer cell migration by disrupting stress fiber integrity and affecting the mutual Rho-GTPase balance.

Topics: Actins; Animals; Apoptosis; Carcinoma, Pancreatic Ductal; Cell Line, Tumor; Cell Movement; Cell Proliferation; Humans; Mice; Neoplasm Metastasis; Pancreatic Neoplasms; Pyrans; rhoA GTP-Binding Protein; Stress Fibers; Tumor Burden

Resistance to gemcitabine in pancreatic cancer (PC) may account for the failure of conventional treatments. Recently, salinomycin (SAL) has been identified as selective inhibitor of cancer stem cells (CSCs). In our study, we aimed to deliver SAL to gemcitabine-resistant PC by the aid of poly ethylene glycol-b-poly lactic acid (PEG-b-PLA) polymeric micelles (PMs).. SAL-loaded PMs were prepared and investigated in terms of pharmaceutical properties. MTT and Annexin V/PI assays were used to study cell proliferation and apoptosis in AsPC-1 cells in response to treatment with SAL micellar formulations. Alterations in CSC phenotype, invasion strength, and mRNA expression of epithelial mesenchymal transition (EMT) markers were also determined in the treated cells. In vivo antitumor study was performed in Balb/c AsPC-1 xenograft mice.. PM formulations of SAL were prepared in suitable size and loading traits. In gemcitabine-resistant AsPC-1 cells, SAL was found to significantly increase cell mortality and apoptosis. It was also observed that SAL micellar formulations inhibited invasion and harnessed EMT in spite of induced expression of Snail. The in vivo antitumor experiment showed significant tumor eradication and the highest survival probability in mice treated with SAL PMs.. The obtained results showed the efficacy of SAL nano-formulation against PC tumor cells.

Topics: Animals; Antineoplastic Agents; Apoptosis; Cell Line, Tumor; Cell Survival; Chromatography, High Pressure Liquid; Deoxycytidine; Drug Carriers; Drug Liberation; Drug Resistance, Neoplasm; Flow Cytometry; Gemcitabine; Humans; Mice; Mice, Inbred BALB C; Micelles; NIH 3T3 Cells; Pancreatic Neoplasms; Particle Size; Polyethylene Glycols; Pyrans; Solubility; Surface Properties; Xenograft Model Antitumor Assays

Survival rates associated with pancreatic cancer remain dismal despite advancements in detection and experimental treatment strategies. Genetically engineered mouse models of pancreatic tumorigenesis have gained considerable attention based on their ability to recapitulate key clinical features of human disease including chemotherapeutic resistance and fibrosis. However, it is unclear if transgenic systems exemplified by the Kras(G12D)/Trp53(R172H)/Pdx-1-Cre (KPC) mouse model recapitulate the functional heterogeneity of human pancreatic tumors harboring distinct cells with tumorigenic properties. To facilitate tracking of heterogeneous tumor cell populations, we incorporated a luciferase-based tag into the genetic background of the KPC mouse model. We isolated pancreatic cancer cells from multiple independent tumor lines and found that roughly 1 out of 87 cells exhibited tumorigenic capability. Notably, this frequency is significantly higher than reported for human pancreatic adenocarcinomas. Cancer stem cell (CSC) markers, including CD133, CD24, Sca-1, and functional Aldefluor activity, were unable to discriminate tumorigenic from nontumorigenic cells in syngeneic transplants. Furthermore, three-dimensional spheroid cultures originating from KPC tumors did not enrich for cells with stem-like characteristics and were not significantly more tumorigenic than cells cultured as monolayers. Additionally, we did not observe significant differences in response to gemcitabine or salinomycin in several isolated subpopulations. Taken together, these studies show that the hierarchical organization of CSCs in human disease is not recapitulated in a commonly used mouse model of pancreatic cancer and therefore provide a new view of the phenotypic and functional heterogeneity of tumor cells.

Topics: AC133 Antigen; Animals; Antigens, CD; Antigens, Ly; Antimetabolites, Antineoplastic; Biomarkers, Tumor; CD24 Antigen; Cell Transformation, Neoplastic; Deoxycytidine; Disease Models, Animal; Gemcitabine; Glycoproteins; Luciferases; Membrane Proteins; Mice; Mice, Inbred C57BL; Mice, Transgenic; Neoplasms, Experimental; Neoplastic Stem Cells; Pancreas; Pancreatic Neoplasms; Peptides; Phenotype; Proto-Oncogene Proteins p21(ras); Pyrans; Spheroids, Cellular; Staining and Labeling; Tumor Cells, Cultured; Tumor Suppressor Protein p53

Previous research has documented that a subpopulation of pancreatic cancer cells, named cancer stem cells (CSCs), harbor stem cell-like properties. Here, we examined the efficacy of combined treatments of salinomycin and gemcitabine in human pancreatic cancer cells. Salinomycin inhibited the growth of CSCs, while gemcitabine suppressed the viability of non-CSCs. Consistently, in vivo studies showed that salinomycin combined with gemcitabine could eliminate the engraftment of human pancreatic cancer more effectively than the individual agents. These data indicated that administration of salinomycin, which targets CSCs, may constitute a potential therapeutic strategy for improving the efficacy of gemcitabine to eradicate pancreatic cancer.

Topics: AC133 Antigen; Animals; Antigens, CD; Antimetabolites, Antineoplastic; Antineoplastic Combined Chemotherapy Protocols; Cell Line, Tumor; Cell Proliferation; Deoxycytidine; Flow Cytometry; Gemcitabine; Glycoproteins; Humans; Male; Mice; Mice, Nude; Neoplastic Stem Cells; Pancreatic Neoplasms; Peptides; Pyrans; Xenograft Model Antitumor Assays