salinomycin and Cell-Transformation--Neoplastic

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

Recent studies have identified a small population of highly tumorigenic cells with stem cell properties in human breast and other solid tumors that are considered to be the source of tumor initiation and maintenance; these cells are referred to as cancer stem cells (CSCs). Preclinical data suggest that current breast cancer treatment strategies lead to CSC enrichment, contributing to chemotherapy and radiotherapy resistance, although a strong correlation with clinical parameters and prognosis is yet to be established. Importantly, overcoming treatment failure by effective targeting of CSCs may be an appealing approach, potentially leading to improved clinical outcomes for patients with breast cancer. Several preclinical studies provide promising results that support this hypothesis. The purpose of this review is to summarize the role of CSCs in breast cancer recurrence and resistance and to discuss current attempts of CSC targeting.

Topics: Aldehyde Dehydrogenase 1 Family; Breast Neoplasms; CD24 Antigen; Cell Differentiation; Cell Transformation, Neoplastic; Disease Progression; Drug Resistance, Neoplasm; Female; Humans; Hyaluronan Receptors; Isoenzymes; Metformin; Neoplasm Invasiveness; Neoplastic Stem Cells; Pyrans; Retinal Dehydrogenase; Treatment Outcome

Evidence indicated that GATA5 may suppress hepatocellular carcinoma (HCC) cell malignant transformation, but the mechanism of how GATA5 affects cancer cell reprogramming to inhibit HCC malignant behaviour is still unclear. In this study, we report that the expression of β-catenin and reprogramming genes p-Oct4, Nanog, Klf4, c-myc and EpCAM was significantly higher in HCC tissues compared to normal liver tissues. In contrast, the expression of GATA5 was significantly lower in HCC tissues compared to normal liver tissues. Transfection of CDH-GATA5 vectors into HCC cells (HLE, Bel 7402 and PLC/PRF/5 cells) increased the GATA5 expression and decreased the expression of β-catenin and reprogramming genes p-Oct4, Nanog, Klf4, c-myc and EpCAM. Increased GATA5 expression by transfection with its expression vectors was also able to inhibit the cell growth, colony formation and capability of migration, invasion, while promoting apoptosis in HCC cells. Results revealed that GATA5 co-localization with β-catenin in the cytoplasm, preventing β-catenin from entering the nucleus. Treatment with the specific Wnt/β-catenin pathway inhibitor salinomycin was able to reduce the expression of β-catenin and reprogramming genes. Salinomycin exerted a similar influence as GATA5, and siRNA-GATA5 restored β-catenin and reprogramming gene expression. This study demonstrates that an increase in the expression of GATA5 inhibits the expression of β-catenin and reprogramming genes and suppresses tumour growth, colony formation, metastasis and invasion, while promoting apoptosis in HCC cells. The mechanism of GATA5 inhibiting the malignant behaviours of HCC cells may involve in the disruption of the Wnt/β-catenin pathway and the reduction of reprogramming gene expression.

Topics: Adult; Aged; Apoptosis; beta Catenin; Carcinoma, Hepatocellular; Case-Control Studies; Cell Line, Tumor; Cell Movement; Cell Proliferation; Cell Transformation, Neoplastic; Epithelial Cell Adhesion Molecule; Female; GATA5 Transcription Factor; Gene Expression Regulation, Neoplastic; Hepatocytes; Humans; Kruppel-Like Factor 4; Kruppel-Like Transcription Factors; Liver Neoplasms; Male; Middle Aged; Nanog Homeobox Protein; Octamer Transcription Factor-3; Proto-Oncogene Proteins c-myc; Pyrans; RNA, Small Interfering; Wnt Signaling Pathway

The aim of this study is to investigate the efficacy of combining a histone deacetylase inhibitor (LBH589) and a breast cancer stem cells (BCSC)-targeting agent (salinomycin) as a novel combination therapy for triple-negative breast cancer (TNBC). We performed in vitro studies using the TNBC cell lines to examine the combined effect. We used the mammosphere and ALDEFLUOR assays to estimate BCSC self-renewal capacity and distribution of BCSCs, respectively. Synergistic analysis was performed using CalcuSyn software. For in vivo studies, aldehyde dehydrogenase 1 ALDH1-positive cells were injected into non-obese diabetic/severe combined immunodeficiency gamma (NSG) mice. After tumor formation, mice were treated with LBH589, salinomycin, or in combination. In a second mouse model, HCC1937 cells were first treated with each treatment and then injected into NSG mice. For mechanistic analysis, immunohistochemistry and Western blot analysis were performed using cell and tumor samples. HCC1937 cells displayed BCSC properties including self-renewal capacity, an ALDH1-positive cell population, and the ability to form tumors. Treatment of HCC1937 cells with LBH589 and salinomycin had a potent synergistic effect inhibiting TNBC cell proliferation, ALDH1-positive cells, and mammosphere growth. In xenograft mouse models treated with LBH589 and salinomycin, the drug combination effectively and synergistically inhibited tumor growth of ALDH1-positive cells. The drug combination exerted its effects by inducing apoptosis, arresting the cell cycle, and regulating epithelial-mesenchymal transition (EMT). Combination of LBH589 and salinomycin has a synergistic inhibitory effect on TNBC BCSCs by inducing apoptosis, arresting the cell cycle, and regulating EMT; with no apparent associated severe toxicity. This drug combination could therefore offer a new targeted therapeutic strategy for TNBC and warrants further clinical study in patients with TNBC.

Topics: Animals; Antineoplastic Agents; Apoptosis; Cell Cycle Checkpoints; Cell Line, Tumor; Cell Proliferation; Cell Self Renewal; Cell Transformation, Neoplastic; Disease Models, Animal; Drug Synergism; Epithelial-Mesenchymal Transition; Female; Histone Deacetylase Inhibitors; Humans; Hydroxamic Acids; Indoles; Mice; Neoplastic Stem Cells; Panobinostat; Pyrans; Triple Negative Breast Neoplasms; Tumor Burden; Tumor Cells, Cultured; 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

Treatment resistance significantly inhibits the efficiency of targeted cancer therapies in drug-sensitive genotypes. In the current work, we studied mechanisms for rapidly occurring, adaptive resistance in targeted therapy-sensitive lung, breast, and melanoma cancer cell lines. The results show that in ALK translocated lung cancer lines H3122 and H2228, cells with cancer stem-like cell features characterized by high expression of cancer stem cell markers and/or in vivo tumorigenesis can mediate adaptive resistance to oncogene ablative therapy. When pharmacological ablation of ALK oncogene was accompanied with PI3K inhibitor or salinomycin therapy, cancer stem-like cell features were reversed which was accompanied with decreased colony formation. Furthermore, co-targeting was able to block the formation of acquired resistance in H3122 line. The results suggest that cells with cancer stem-like cell features can mediate adaptive resistance to targeted therapies. Since these cells follow the stochastic model, concurrent therapy with an oncogene ablating agent and a stem-like cell-targeting drug is needed for maximal therapeutic efficiency.

Topics: Aldehyde Dehydrogenase; Anaplastic Lymphoma Kinase; Animals; Antineoplastic Agents; Breast Neoplasms; Carcinoma, Non-Small-Cell Lung; Cell Line, Tumor; Cell Transformation, Neoplastic; Drug Resistance, Neoplasm; Drug Synergism; Female; Humans; Lung Neoplasms; MCF-7 Cells; Melanoma; Mice; Mice, Inbred NOD; Mice, SCID; Molecular Targeted Therapy; Neoplasms; Oxidoreductases Acting on CH-NH Group Donors; Phosphoinositide-3 Kinase Inhibitors; Pyrans; Receptor Protein-Tyrosine Kinases; Xenograft Model Antitumor Assays