salinomycin and Adenocarcinoma

The search for anticancer drugs has led researchers to study salinomycin, an ionophore antibiotic that selectively destroys cancer stem cells. In this study, salinomycin was assessed in two human cell lines, a breast adenocarcinoma (MCF-7) and a non-tumor breast cell line (HB4a), to verify its selective action against tumor cells. Real-time assessment of cell proliferation showed that HB4a cells are more resistant to salinomycin than MCF-7 tumor cell line, and these data were confirmed in a cytotoxicity assay. The half maximal inhibitory concentration (IC50) values show the increased sensitivity of MCF-7 cells to salinomycin. In the comet assay, only MCF-7 cells showed the induction of DNA damage. Flow cytometric analysis showed that cell death by apoptosis/necrosis was only induced in the MCF-7 cells. The increased expression of GADD45A and CDKN1A genes was observed in all cell lines. Decreased expression of CCNA2 and CCNB1 genes occurred only in tumor cells, suggesting G2/M cell cycle arrest. Consequently, cell death was activated in tumor cells through strong inhibition of the antiapoptotic genes BCL-2, BCL-XL, and BIRC5 genes in MCF-7 cells. These data demonstrate the selectivity of salinomycin in killing human mammary tumor cells. The cell death observed only in MCF-7 tumor cells was confirmed by gene expression analysis, where there was downregulation of antiapoptotic genes. These data contribute to clarifying the mechanism of action of salinomycin as a promising antitumor drug and, for the first time, we observed the higher resistance of HB4a non-tumor breast cells to salinomycin.

Topics: Adenocarcinoma; Antineoplastic Agents; Apoptosis; Apoptosis Regulatory Proteins; Breast Neoplasms; Cell Cycle Proteins; Cell Proliferation; Comet Assay; DNA Damage; Dose-Response Relationship, Drug; Female; Flow Cytometry; Gene Expression Regulation, Neoplastic; Humans; Inhibitory Concentration 50; M Phase Cell Cycle Checkpoints; Mammary Glands, Human; MCF-7 Cells; Pyrans; Reverse Transcriptase Polymerase Chain Reaction; Time Factors

Future curative cancer chemotherapies have to overcome tumor cell heterogeneity and plasticity. To test the hypothesis that the tumor suppressor maspin may reduce microenvironment-dependent prostate tumor cell plasticity and thereby modulate drug sensitivity, we established a new schematic combination of two-dimensional (2D), three-dimensional (3D), and suspension cultures to enrich prostate cancer cell subpopulations with distinct differentiation potentials. We report here that depending on the level of maspin expression, tumor cells in suspension and 3D collagen I manifest the phenotypes of stem-like and dormant tumor cell populations, respectively. In suspension, the surviving maspin-expressing tumor cells lost the self-renewal capacity, underwent senescence, lost the ability to dedifferentiate in vitro, and failed to generate tumors in vivo. Maspin-nonexpressing tumor cells that survived the suspension culture in compact tumorspheres displayed a higher level of stem cell marker expression, maintained the self-renewal capacity, formed tumorspheres in 3D matrices in vitro, and were tumorigenic in vivo. The drug sensitivities of the distinct cell subpopulations depend on the drug target and the differentiation state of the cells. In 2D, docetaxel, MS275, and salinomycin were all cytotoxic. In suspension, while MS275 and salinomycin were toxic, docetaxel showed no effect. Interestingly, cells adapted to 3D collagen I were only responsive to salinomycin. Maspin expression correlated with higher sensitivity to MS275 in both 2D and suspension and to salinomycin in 2D and 3D collagen I. Our data suggest that maspin reduces prostate tumor cell plasticity and enhances tumor sensitivity to salinomycin, which may hold promise in overcoming tumor cell heterogeneity and plasticity.

Topics: Adenocarcinoma; Animals; Antineoplastic Agents; Benzamides; Cell Adhesion; Cell Culture Techniques; Cell Dedifferentiation; Cell Line, Tumor; Cell Plasticity; Cell Self Renewal; Cellular Senescence; Docetaxel; Drug Resistance, Neoplasm; Gene Expression Profiling; Heterografts; Humans; Male; Mice; Mice, Nude; Neoplasm Proteins; Neoplasm Transplantation; Neoplastic Stem Cells; Phenotype; Prostatic Neoplasms; Pyrans; Pyridines; Serpins; Suspensions; Taxoids; Tumor Microenvironment

Cancer stem cells (CSCs) are a specific subset of cancer cells that sustain tumor growth and dissemination. They might represent a significant treatment target to reduce malignant progression and prevent tumor recurrence. In solid tumors, several hierarchically organized CSC clones coexist, even within a single tumor. Among them, CSCs displaying an embryonic stem cell 'stemness' signature, based on the expression of Oct-4, Nanog and Sox2, are present in distinct high-grade tumor types associated with poor prognosis. We previously designed a model to isolate pure populations of these CSCs from distinct solid tumors and used it to screen for molecules showing selective toxicity for this type of CSC. Here we show that human immunodeficiency virus (HIV)-protease inhibitors (HIV-PIs) specifically target CSCs expressing an embryonic signature derived from tumors with distinct origins. They reduced proliferation in a dose-dependent manner with a higher specificity as compared with the total population of cancer cells and/or healthy stem cells, and they were efficient in inducing cell death. Lopinavir was the most effective HIV-PI among those tested. It reduced self-renewal and induced apoptosis of CSCs, subsequently impairing in vivo CSC-induced allograft formation. Two key pharmacophores in the LPV structure were also identified. They are responsible for the specificity of CSC targeting and also for the overall antitumoral activity. These results contribute to the identification of molecules presenting selective toxicity for CSCs expressing an embryonic stemness signature. This paves the way to promising therapeutic opportunities for patients suffering from solid cancer tumors of poor prognosis.

Topics: Adenocarcinoma; Animals; Antineoplastic Agents; Apoptosis; Cell Proliferation; Disease Progression; Drug Screening Assays, Antitumor; HIV Protease Inhibitors; Humans; Inhibitory Concentration 50; Intestinal Neoplasms; Lopinavir; Mesenchymal Stem Cells; Mice; Mice, SCID; Nelfinavir; Neoplasm Transplantation; Neoplastic Stem Cells; Pyrans; Structure-Activity Relationship; Tumor Cells, Cultured

Lung cancer is a leading cause of death in human. Cancer stem cells have been regarded as basis for failure of current therapeutic options. Salinomycin was shown to kill these cancer stem cells in some types of cancer such as breast cancer and leukemia. The in vitro anticancer activities of salinomycin have been validated against the lung cancer cell line A549 via sulforhodamine B and colony formation assay. Salinomycin has been demonstrated to significantly rupture the in vitro lung cancer tumorospheres from ALDH positive A549 lung cells using flow cytometry. Expression of stem cell markers OCT-4, NANOG and SOX2 in ALDH positive A549 lung cells was decreased significantly by real-time RT-PCR analysis after 24 hour salinomycin treatment. Taken together, salinomycin may provide a promising approach for lung cancer chemotherapy.

Topics: Adenocarcinoma; Adenocarcinoma of Lung; Antineoplastic Agents; Biomarkers; Cell Line, Tumor; Humans; Lung Neoplasms; Neoplastic Stem Cells; Pyrans; Structure-Activity Relationship