Project description:Screens for agents that specifically kill epithelial cancer stem cells (CSCs) have not been possible due to the rarity of these cells within tumor cell populations and their relative instability in culture. We describe here an approach to screening for agents with epithelial CSC-specific toxicity. We implemented this method in a chemical screen and discovered compounds showing selective toxicity for breast CSCs. One compound, salinomycin, reduces the proportion of CSCs by >100-fold relative to paclitaxel, a commonly used breast cancer chemotherapeutic drug. Treatment of mice with salinomycin inhibits mammary tumor growth in vivo and induces increased epithelial differentiation of tumor cells. In addition, global gene expression analyses show that salinomycin treatment results in the loss of expression of breast CSC genes previously identified by analyses of breast tissues isolated directly from patients. This study demonstrates the ability to identify agents with specific toxicity for epithelial CSCs Experiment Overall Design: Experimentally transformed HMLER breast cancer cells were treated in culture with either paclitaxel (10nM) or salinomycin (1uM) for one week. There were three biologic replicates for each treatment condition.
Project description:Cancer stem cells are believed to play a crucial role in cancer recurrence due to their resistance to conventional chemotherapy and capacity for self-renewal. Recent studies have reported that salinomycin, a livestock antibiotic, selectively targets breast cancer stem cells 100-fold more effectively than paclitaxel. In our study we sought to determine the effects of salinomycin on head and neck squamous cell carcinoma (HNSCC) stem cells. We show that salinomycin is able to decrease cell viability and induce apoptosis. In combination with the chemotherapeutic agents cisplatin and paclitaxel, salinomycin synergistically killed HNSCC cancer stem cells more effectively than either drug alone. Furthermore, we observed that salinomycin decreases stem cell properties as shown by a significant reduction in sphere formation and a decrease of both CD44 and BMI-1. Contrary to expectations, salinomycin caused an induction of EMT as shown by an increase in Snail and Vimentin, and a decrease in E-cadherin expression. Even though EMT was induced, salinomycin caused a decrease in invasion through a membrane. In search of a possible mechanism, the effects on the Akt pathway were explored. Interestingly, salinomycin also induced phosphorylation of Akt. Activation of EMT and Akt are both tightly associated with an increase in stemness, which brings to question the relationship between CSCs and these two fundamental pathways. Taken together, our findings indicate that salinomycin shows promise as a novel treatment for HNSCC despite an activation of EMT and Akt. MicroRNA obtained from JLO-1 cells treated for 48 hours in varying doses of salinomycin. Changes in microRNA expression are analyzed by normalizing expression values with the control sample.
Project description:Cancer stem cells are believed to play a crucial role in cancer recurrence due to their resistance to conventional chemotherapy and capacity for self-renewal. Recent studies have reported that salinomycin, a livestock antibiotic, selectively targets breast cancer stem cells 100-fold more effectively than paclitaxel. In our study we sought to determine the effects of salinomycin on head and neck squamous cell carcinoma (HNSCC) stem cells. We show that salinomycin is able to decrease cell viability and induce apoptosis. In combination with the chemotherapeutic agents cisplatin and paclitaxel, salinomycin synergistically killed HNSCC cancer stem cells more effectively than either drug alone. Furthermore, we observed that salinomycin decreases stem cell properties as shown by a significant reduction in sphere formation and a decrease of both CD44 and BMI-1. Contrary to expectations, salinomycin caused an induction of EMT as shown by an increase in Snail and Vimentin, and a decrease in E-cadherin expression. Even though EMT was induced, salinomycin caused a decrease in invasion through a membrane. In search of a possible mechanism, the effects on the Akt pathway were explored. Interestingly, salinomycin also induced phosphorylation of Akt. Activation of EMT and Akt are both tightly associated with an increase in stemness, which brings to question the relationship between CSCs and these two fundamental pathways. Taken together, our findings indicate that salinomycin shows promise as a novel treatment for HNSCC despite an activation of EMT and Akt.
Project description:Screens for agents that specifically kill epithelial cancer stem cells (CSCs) have not been possible due to the rarity of these cells within tumor cell populations and their relative instability in culture. We describe here an approach to screening for agents with epithelial CSC-specific toxicity. We implemented this method in a chemical screen and discovered compounds showing selective toxicity for breast CSCs. One compound, salinomycin, reduces the proportion of CSCs by >100-fold relative to paclitaxel, a commonly used breast cancer chemotherapeutic drug. Treatment of mice with salinomycin inhibits mammary tumor growth in vivo and induces increased epithelial differentiation of tumor cells. In addition, global gene expression analyses show that salinomycin treatment results in the loss of expression of breast CSC genes previously identified by analyses of breast tissues isolated directly from patients. This study demonstrates the ability to identify agents with specific toxicity for epithelial CSCs
Project description:Epithelial-to-mesenchymal transition (EMT) gives rise to cells with properties similar to cancer stem cells (CSCs) that drive tumor metastasis. Recently, a screening of a large compound library on a breast EMT model has identified salinomycin, a K+/H+ ionophore, as a highly selective drug towards CSCs. We used the same EMT model to show that salinomycin targets Golgi apparatus. We have performed RNA-seq analysis on HMLE-Twist and HMLE-pBp cells (EMT and non-EMT) that were either mock treated or treated for 24h with micro molar concentration (0.2uM) of salinomycin. Salinomycin induced expression of genes enriched by known ER and Golgi stressors.
Project description:Ferroptosis constitutes a promising therapeutic strategy against cancer by efficiently targeting the highly tumorigenic and treatment-resistant cancer stem cells (CSCs). We previously showed that the lysosomal iron-targeting drug Salinomycin (Sal) was able to eliminate CSCs by triggering ferroptosis. Here, in a well-established breast CSCs model (human mammary epithelial HMLER CD24low/CD44high), we identified that pharmacological inhibition of mechanistic target of rapamycin (mTOR), suppresses Sal-induced ferroptosis. Mechanistically, mTOR inhibition modulates iron cellular flux and prevents the iron and ROS bursts induced by Sal. Besides, integration of multi-omics data identified mitochondria as a key target of Sal action. We demonstrated that mTOR inhibition prevents Sal-induced mitochondrial functional and structural alteration, and that Sal-induced metabolic plasticity is mainly dependent on the mTOR pathway. Overall, our findings provide experimental evidences on the detailed mechanisms of mTOR as a crucial effector of Sal-induced ferroptosis, and gives proof-of-concept that careful evaluation of such combination therapy (here mTOR and ferroptosis co-targeting) is required for effective treatment.
Project description:We conduct transcriptome comparison of HMLER-derived CD44H,CD44LS and CD44L subpopulation cells to gain transcriptomic insights on the differences between breast cancer stem cells and non-breast cancer stem cells.