salinomycin and Neoplasm-Metastasis

Cancer stem cells (CSCs) represent a subpopulation of tumour cells endowed with self-renewal and multi-lineage differentiation capacity but also with an innate resistance to cytotoxic agents, a feature likely to pose major clinical challenges towards the complete eradication of minimal residual disease in cancer patients. Operationally, CSCs are defined by their tumour-propagating ability when serially transplanted into immune-compromised mice and by their capacity to fully recapitulate the original heterogeneity of cell types observed in the primary lesions they are derived from. CSCs were first identified in haematopoietic malignancies and later in a broad spectrum of solid tumours including those of the breast, colon and brain. Notably, several CSC characteristics are relevant to metastasis, such as motility, invasiveness and, as mentioned above, resistance to DNA damage-induced apoptosis. Here, we have reviewed the current literature on the relation between CSCs and metastasis formation. Preliminary studies on cancer cell lines and patient-derived material suggest a rate-limiting role for stem-like cells in the processes of tumour cell dissemination and metastasis formation. However, additional studies are needed to deliver formal proof of their identity as the cell of origin of recurrences at distant organ sites. Nevertheless, several studies have already provided pre-clinical evidence of the efficacy of novel therapies directed against disseminated CSCs.

Topics: Animals; Antineoplastic Agents; Cell Differentiation; Cell Transformation, Neoplastic; Epithelial-Mesenchymal Transition; Gene Expression; Humans; Mice; Neoplasm Metastasis; Neoplasms; Neoplastic Stem Cells; Pyrans

Drug combination is considered to be the cornerstone of cancer treatment. Simultaneous administration of two or more drugs but at lower doses not only increases cytotoxic effects on tumor cells, but also reduces side effects and possibly overcomes drug resistance. Salinomycin is a well-known cancer stem cell killer, and dichloroacetate is a pyruvate dehydrogenase kinase inhibitor that exclusively targets cells with altered mitochondrial activity, a characteristic being common to most of the cancer cells. In our recent study, we have demonstrated that salinomycin exerted a cytotoxic effect on colorectal carcinoma cells in the 2D and 3D cultures and provided evidence that the mechanism of their synergy was mediated by dichloroacetate-dependent inhibition of the activity of multidrug resistance proteins. In the current work, we confirmed the synergistic cytotoxic properties of salinomycin and dichloroacetate in the 2D and 3D cultures of Lewis lung carcinoma (LLC1) cells. To verify if a synergistic effect of these compounds persisted in vivo, we performed series of experiments using a syngeneic LLC1-C57BL/6 mouse model and demonstrated that combination therapy with salinomycin and DCA increased the survival rate of allografted mice, inhibited metastatic site formation and reduced the populations of cancer stem cells as well as cells that underwent the epithelial-to-mesenchymal transition. Our results demonstrate that a synergistic effect of salinomycin and dichloroacetate exists not only in vitro but also in vivo and suggest their benefits in the treatment of metastatic cancers.

Topics: Animals; Apoptosis; Biomarkers, Tumor; Carcinoma, Lewis Lung; Cell Line, Tumor; Cell Proliferation; Dichloroacetic Acid; Drug Synergism; Epithelial-Mesenchymal Transition; Mice, Inbred C57BL; Neoplasm Metastasis; Neoplastic Stem Cells; Pyrans

Long non-coding RNAs (lncRNAs) contribute to the initiation and progression of various tumors, including head and neck squamous carcinoma (HNSCC), which is a common malignancy with high morbidity and low survival rate. However, the mechanism of lncRNAs in HNSCC tumorigenesis remains largely unexplored. In this work, we identified a novel lncRNA AC104041.1 which is highly upregulated and correlated with poor survival in HNSCC patients. Moreover, AC104041.1 overexpression significantly promoted tumor growth and metastasis of HNSCC in vitro and in vivo. Mechanistically, AC104041.1 mainly located in the cytoplasm and could function as ceRNA (competing endogenous RNA) for miR-6817-3p, thereby stabilized Wnt2B, and consequently inducing β-catenin nuclear translocation and activation. Moreover, we demonstrate that salinomycin, which as a highly effective antibiotic in the elimination of cancer stem cells through the Wnt/β-catenin signaling, could enhance the inhibition of tumor growth by antisense oligonucleotides (ASO) targeting AC104041.1 in HNSCC cells and PDXs (patient-derived xenograft) model. Thus, our data provide preclinical evidence to support a novel strategy of ASOs targeting AC104041.1 in combination with salinomycin and may as a beneficial treatment approach for HNSCC.

Topics: Animals; Antineoplastic Agents; Carcinogenesis; Cell Line, Tumor; Cell Movement; Cell Proliferation; Female; Gene Expression Regulation, Neoplastic; Glycoproteins; Head and Neck Neoplasms; Humans; Mice, Inbred BALB C; Mice, Nude; MicroRNAs; Neoplasm Metastasis; Oligonucleotides, Antisense; Oncogenes; Pyrans; RNA, Long Noncoding; Squamous Cell Carcinoma of Head and Neck; Survival Analysis; Wnt Proteins; Wnt Signaling Pathway

Salinomycin is a polyether antibiotic with selective activity against human cancer stem cells. The impact of salinomycin on patient-derived primary human colorectal cancer cells has not been investigated so far. Thus, here we aimed to investigate the activity of salinomycin against tumor initiating cells isolated from patients with colorectal cancer.. Primary tumor-initiating cells (TIC) isolated from human patients with colorectal liver metastases or from human primary colon carcinoma were exposed to salinomycin and compared to treatment with 5-FU and oxaliplatin. TICs were injected subcutaneously into NOD/SCID mice to induce a patient-derived mouse xenograft model of colorectal cancer. Animals were treated either with salinomycin, FOLFOX regimen, or salinomycin and FOLFOX. Human colorectal cancer cells were used to delineate an underlying molecular mechanism of salinomycin in this tumor entity.. Applying TICs isolated from human patients with colorectal liver metastases or from human primary colon carcinoma, we demonstrated that salinomycin exerts increased antiproliferative activity compared to 5-fluorouracil and oxaliplatin treatment. Consistently, salinomycin alone or in combination with FOLFOX exerts superior antitumor activity compared to FOLFOX therapy in a patient-derived mouse xenograft model of colorectal cancer. Salinomycin induces apoptosis of human colorectal cancer cells, accompanied by accumulation of dysfunctional mitochondria and reactive oxygen species. These effects are associated with expressional down-regulation of superoxide dismutase-1 (SOD1) in response to salinomycin treatment.. Collectively, the results of this pre-clinical study indicate that salinomycin alone or in combination with 5-fluorouracil and oxaliplatin exerts increased antitumoral activity compared to common chemotherapy.

Topics: Aged; Aged, 80 and over; Animals; Apoptosis; Colorectal Neoplasms; Female; HCT116 Cells; Humans; Liver Neoplasms; Male; Mice, Inbred NOD; Mice, SCID; Middle Aged; Mitochondria; Neoplasm Metastasis; Pyrans; Reactive Oxygen Species; Xenograft Model Antitumor Assays

Epithelial-to-mesenchymal transition (EMT) is the major cause of breast cancer to initiate invasion and metastasis. Salinomycin (Sal) has been found as an effective chemical compound to kill breast cancer stem cells. However, the effect of Sal on invasion and metastasis of breast cancer is unclear. In the present study, we showed that Sal reversed transforming growth factor-β1 (TGF-β1) induced invasion and metastasis accompanied with down-regulation of MMP-2 by experiments on human breast cancer cell line MCF-7. Sal was able to inhibit TGF-β1-induced EMT phenotypic transition and the activation of key signaling molecules involved in Smad (p-Smad2/3,Snail1) and non-Smad (β-catenin, p-p38 MAPK) signals which cooperatively regulate the induction of EMT. Importantly, in a series of breast cancer specimens, we found strong correlation among E-cadherin expression, β-catenin expression, and the lymph node metastatic potential of breast cancer. Our research suggests that Sal is promised to be a chemotherapeutic drug by suppressing the metastasis of breast cancer.

Topics: Anti-Bacterial Agents; Antineoplastic Agents; Breast Neoplasms; Epithelial-Mesenchymal Transition; Female; Humans; MCF-7 Cells; Neoplasm Invasiveness; Neoplasm Metastasis; Neoplastic Stem Cells; Pyrans; Signal Transduction; Smad Proteins; Transforming Growth Factor beta1

Cancer stem cell (CSC) inhibitors are a new category of investigational drugs to treat metastasis. Salinomycin (Sali) is one of most studied CSC inhibitors and has reached clinical tests. Several drug carriers have been developed to improve efficacy of Sali. However, Sali has not been shown to inhibit metastasis from orthotopic tumors, the gold standard for metastasis. To fill this gap, we developed an immune-tolerant, elastin-like polypeptide (iTEP)-based nanoparticle (iTEP-Sali-ABA NP) that released 4-(aminomethyl)benzaldehyde-modified Sali (Sali-ABA) under acidic conditions. We found that the NP increased the area under the curve (AUC) of Sali-ABA by 30-fold and the tumor accumulation by 3.4-fold. Furthermore, no metastasis was detected in any of the mice given the NP. However, all the mice died of primary tumor burdens. To overcome primary tumor growth and improve the overall survival, we applied a combination therapy consisting of the iTEP-Sali-ABA NP and iTEP NP-delivered paclitaxel. This therapy effectively retarded primary tumor growth, and most importantly, improved the overall survival. In conclusion, delivery of Sali-ABA by the NP, alone or in combination with paclitaxel, was more effective than free Sali-ABA in decreasing metastasis and increasing survival. This iTEP-Sali-ABA NP represents a novel and clinically promising therapy to combat metastasis.

Topics: Animals; Antineoplastic Combined Chemotherapy Protocols; Benzaldehydes; Breast Neoplasms; Cell Line, Tumor; Cell Proliferation; Cell Survival; Elastin; Electrophoresis, Polyacrylamide Gel; Female; Humans; Immune Tolerance; Mice, Inbred BALB C; Nanoparticles; Neoplasm Metastasis; Paclitaxel; Peptides; Pyrans; Tissue Distribution

The polyether antibiotic Salinomycin (Sal) is regarded as an inhibitor of cancer stem cells. Its effectiveness on human colorectal cancer (CRC) cells in vitro has been demonstrated before. The aim of this study was to establish a murine model to investigate the effectiveness of Sal in vivo. Furthermore, we investigated the impact of Sal on Wnt/β-catenin signaling in human CD133. Sal markedly impaired tumor cell viability, proliferation and migration, and induced necrotic cell death in vitro. CRC growth in vivo was likewise inhibited upon Sal treatment. Interference with Wnt signaling and reduced expression of the Wnt target genes Fibronectin and Lgr5 indicates a novel molecular mechanism, mediating anti-tumoral effects of Sal in CRC.. Sal effectively impairs CRC growth in vivo. Furthermore, Sal acts as an inhibitor of Wnt/β-catenin signaling. Thus, Salinomycin represents a promising candidate for clinical CRC treatment.

Topics: AC133 Antigen; Animals; Cell Line, Tumor; Cell Movement; Cell Proliferation; Cell Survival; Colorectal Neoplasms; Gene Expression Regulation, Neoplastic; Humans; Mice; Mice, Inbred BALB C; Neoplasm Metastasis; Pyrans; Wnt Signaling Pathway; 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

To develop novel iRGD (internalizing Arg-Gly-Asp peptide)-conjugated DSPE-PEG2000 nanomicelles (M-SAL-iRGD) for delivery of salinomycin to both liver cancer cells and cancer stem cells (CSCs).. The characterization, antitumor activity and mechanism of action of M-SAL-iRGD were evaluated.. M-SAL-iRGD possessed a small size of around 10 nm, and drug encapsulation efficacy higher than 90%. M-SAL-iRGD showed significantly increased cytotoxic effect toward both nontargeted M-SAL (salinomycin-loaded DSPE-PEG2000 nanomicelles) and salinomycin in both liver cancer cells and CSCs. The tissue distribution and antitumor assays in mice bearing liver cancer xenograft confirmed the superior penetration tumor efficacy and antitumor activity of M-SAL-iRGD. M-SAL-iRGD represent a potential effective nanomedicine against liver cancer.

Topics: AC133 Antigen; Animals; Antigens, CD; Cell Line, Tumor; Drug Carriers; Drug Delivery Systems; Gene Expression Regulation, Neoplastic; Glycoproteins; Hep G2 Cells; Humans; Liposomes; Liver Neoplasms; Male; Mice; Mice, Inbred BALB C; Mice, Nude; Micelles; Nanomedicine; Neoplasm Metastasis; Neoplasm Transplantation; Neoplastic Stem Cells; Neuropilin-1; Oligopeptides; Peptides; Phosphatidylethanolamines; Polyethylene Glycols; Pyrans; Rats; Rats, Sprague-Dawley; Tissue Distribution

Tumor spreading is the major threat for cancer patients. The recently published anti-cancer drug salinomycin raised hope for an improved treatment by targeting therapy-refractory cancer stem cells. However, an unambiguous role of salinomycin against cancer cell migration and metastasis formation remains elusive.. We report that salinomycin effectively inhibits cancer cell migration in a variety of cancer types as determined by Boyden chamber assays. Additionally, cells were treated with doxorubicin at a concentration causing a comparable low cytotoxicity, emphasizing the anti-migratory potential of salinomycin. Moreover, single-cell tracking by time-lapse microscopy demonstrated a remarkable effect of salinomycin on breast cancer cell motility. Ultimately, salinomycin treatment significantly reduced the metastatic tumor burden in a syngenic mouse tumor model.. Our findings clearly show that salinomycin can strongly inhibit cancer cell migration independent of the induction of cell death. We furthermore demonstrate for the first time that salinomycin treatment reduces metastasis formation in vivo, strengthening its role as promising anti-cancer therapeutic.

Topics: Animals; Antineoplastic Agents; Breast Neoplasms; Cell Line, Tumor; Cell Movement; Female; Humans; Mice; Mice, Inbred BALB C; Microscopy, Fluorescence; Neoplasm Metastasis; Pyrans; Tumor Burden

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.

Topics: Animals; Antineoplastic Agents; Apoptosis; Cell Line, Tumor; Drug Resistance, Neoplasm; Drug Screening Assays, Antitumor; Gene Expression Regulation, Neoplastic; Humans; Mammary Neoplasms, Experimental; Mice; Mice, Inbred BALB C; Mice, Inbred NOD; Mice, SCID; Neoplasm Metastasis; Neoplasm Transplantation; Neoplastic Stem Cells; Paclitaxel; Pyrans

Topics: Antineoplastic Agents; Drug Screening Assays, Antitumor; Humans; Neoplasm Metastasis; Neoplasms; Neoplastic Stem Cells; Pyrans; Tumor Cells, Cultured

Topics: Antineoplastic Agents; Biomedical Research; Humans; Neoplasm Metastasis; Neoplastic Stem Cells; Pyrans; Secondary Prevention