Objective To investigate the effect of salinomycin on cancer stem cell formation of prostate cancer cell line DU145 and its possible mechanisms,providing theoretical basis for the clinical application of salino-mycin. Methods (1)DU145 cells were treated with salinomycin. The percentage of ALDH+cells,which was used as the marker of cancer stem cells,was detected by flow cytometry.(2)After treated with salmonin,DU145 cells were subjected to Western-Blot analysis for the expression of mTORsignal pathway-related proteins such as p-70s6k, p-p70s6,p-s6 and so on. 3)DU145 cells were treated with salinomycin combined with mTOR signal pathway inhibi-tor rapamycin,and the ALDH+cancer stem cells were detected using flow cytometer. Results (1)Salmonomycin significantly inhibited ALDH-positive cancer stem cells in DU145cell line(inhibition rate in 77.8%),which was twice as high as that of traditional anticancer drug paclitaxel(which has a inhibition rate of 38.64%). This results suggesting that salinomycin would have the effect of inhibiting cancer stem cells. (2)The expression ofm-TOR p-70s6k,p-p70s6 and p-s6 in mTOR signaling pathway was inhibited by salinomycin in a time-dependent and dose-dependent manner,suggesting that salinomycin would inhibite mTOR signaling pathway.(3)Salinomycin combined with rapamycin can decrease the proportion of ALDH-positive DU145 cancer stem cells(inhibition rate in 77.95%), suggesting that salinomycin may inhibit ALDH-positive DU145 stem cells through the mTOR signaling pathway. Conclusion Salinomycin may play an important role in inhibiting cancer stem cells by inhibiting mTOR pathway signaling.

Background and purpose:Amplification of the urokinase plasminogen activator receptor(uPAR)gene is closely associated with poor prognosis in pancreatic cancer patients.uPAR regulates epithelial-mesenchymal transition(EMT)and chemoresistance in pancreatic cancer cells through the mitogen-activated protein kinases(MAPK)signaling pathway,though the specific mechanisms remain unclear.This study aimed to investigate the mechanism by which uPAR promotes proliferation,invasion,and chemoresistance of pancreatic cancer cells by inhibiting autophagy.Methods:Pancreatic cancer tissue samples were collected from patients who underwent surgical resection and biopsy at the Changsha Central Hospital,Affiliated to University of South China(Changsha Central Hospital),between December 2021 and Jun 2022.The study was approved by the Ethics Committee of Changsha Central Hospital(Approval No.:2021-S0182,2022-S0084).Patient-derived organoids(PDOs)from pancreatic cancer samples were cultured in vitro.Six pancreatic cancer cell lines(AsPC-1,PANC-1,CAPAN-1,CAPAN-2,MIA PaCa-2 and PaTu8988T)were used in this study.uPAR-deficient models were constructed using clustered regularly interspaced short palindromic repeats(CRISPR)Cas9 technology.Cell proliferation and invasion abilities were measured using confocal microscopy,Western blot,enzyme-linked immunosorbent assay(ELISA),and MTS assays.Changes in MAPK and autophagy signaling pathways and gemcitabine-induced cell death were analyzed.The synergistic effects of combined treatments were evaluated using gene silencing(siRNA)or autophagy inhibitors.Results:In AsPC-1 cells,uPAR knockout significantly reduced the proliferation and migration abilities of clone cells compared to wild-type cells,as shown by MTS assays and wound healing experiments,and decreased sensitivity to gemcitabine(P＜0.05).Re-expression of uPAR restored the proliferation and invasion abilities of clone cells and partially restored sensitivity to gemcitabine(P＜0.05).Confocal microscopy revealed reduced F-actin and a rounded morphology in clone cells.Western blot analysis showed increased expressions of E-cadherin and Slug,decreased expression of vimentin,and increased expressions of phospho-focal adhesion kinase(p-FAK),p-p38MAPK,and the microtubule-associated protein light chain 3B(LC3B)in clone cells compared to wild-type cells.siRNA results indicated that silencing FAK or p38MAPK or combining autophagy inhibition could resensitize clone cells to gemcitabine(P＜0.05),with p38MAPK silencing reducing LC3B expression.Organoid studies showed varying responses to gemcitabine among 8 organoids,all expressing uPAR.uPAR expression levels were negatively correlated with gemcitabine IC50(r2=0.66,P＜0.05).Three organoids responded well to the combination of gemcitabine and autophagy inhibitors(P＜0.05).Conclusion:uPAR promotes pancreatic cancer cell activity through the p38MAPK signaling pathway,preventing FAK-mediated resistance and cell dormancy.The study suggests that pancreatic cancer patients with high uPAR expression respond better to gemcitabine,while tumors with low uPAR and high p38MAPK expressions may benefit from combined treatment with autophagy inhibitors and cytotoxic chemotherapy.

OBJECTIVE: To study the effects of the overexpression of autophagy-related gene 3 (ATG3) on autophagy and salinomycin-induced apoptosis in breast cancer cells and explore the underlying mechanisms. METHODS: We used the lentivirus approach to establish a breast cancer cell line with stable overexpression of ATG3. Western blotting, immunofluorescence staining and transmission electron microscopy were used to analyze the effect of ATG3 overexpression on autophagy in breast cancer MCF-7 cells. Using the AKT/mTOR agonists SC79 and MHY1485, we analyzed the effect of AKT/mTOR signal pathway activation on ATG3 overexpression-induced autophagy. Western blotting and flow cytometry were used to analyze the effect of autophagy on apoptosis of the ATG3-overexpressing cells treated with salinomycin and 3-MA (an autophagy inhibitor). RESULTS: In ATG3-overexpressing MCF-7 cells, ATG3 overexpression obviously promoted autophagy, inhibited the AKT/mTOR signaling pathway, significantly weakened salinomycin-induced apoptosis ( < 0.01), caused significant reduction of the levels of the pro-apoptotic proteins cleaved-caspase 3 ( < 0.01) and Bax ( < 0.05), and enhanced the expression of the anti-apoptotic protein Bcl-2 ( < 0.05). The inhibition of autophagy obviously weakened the inhibitory effect of ATG3 overexpression on salinomycin-induced apoptosis. CONCLUSIONS ATG3 overexpression promotes autophagy possibly by inhibiting the AKT/mTOR signaling pathway to decrease salinomycin-induced apoptosis in MCF-7 cells, suggesting that autophagy induction might be one of the mechanisms of drug resistance in breast cancer cells.
Acetates ; pharmacology ; Apoptosis ; drug effects ; genetics ; Autophagy ; drug effects ; Autophagy-Related Proteins ; metabolism ; Benzopyrans ; pharmacology ; Breast Neoplasms ; metabolism ; pathology ; Cell Line, Tumor ; Cell Proliferation ; Drug Resistance, Neoplasm ; Female ; Gene Expression Regulation ; Humans ; MCF-7 Cells ; Morpholines ; pharmacology ; Proto-Oncogene Proteins c-akt ; antagonists & inhibitors ; metabolism ; Pyrans ; pharmacology ; TOR Serine-Threonine Kinases ; antagonists & inhibitors ; metabolism ; Triazines ; pharmacology ; Ubiquitin-Conjugating Enzymes ; metabolism