Percentage Of Cancer Stem Cells Research Articles

Deciphering the Interplay: Thieno[2,3-b]pyridine's Impact on Glycosphingolipid Expression, Cytotoxicity, Apoptosis, and Metabolomics in Ovarian Tumor Cell Lines.

Ovarian cancer is among the most prevalent causes of mortality among women. Despite improvements in diagnostic methods, non-specific symptoms and delayed gynecological exams can lead to late-stage ovarian tumor discovery. In this study, the effect of an anti-cancer compound, 3-amino-N-(3-chloro-2-methylphenyl)-5-oxo-5,6,7,8-tetrahydrothieno[2,3-b]quinoline-2-carboxamide (Compound 1), was examined. The impacts of cytotoxicity, apoptosis, and metabolomic changes in ovarian cancer cell lines SK-OV-3 and OVCAR-3, as well as glycosphingolipid (GSL) expression, on cancer stem cells (CSCs), marked as CD49f+, and non-CSCs (CD49f-) were explored. Treatment with Compound 1 reduced the percentage of CSCs compared to non-treated cells (p < 0.001). The functional impact of eight GSLs on CSCs and non-CSCs was examined using flow cytometry. The glycophenotype changed in both cell lines, with increases or decreases in its expression, after the treatment. These findings raise the possibility of specifically targeting CSCs in ovarian cancer therapy. Additionally, treatment with Compound 1 resulted in statistically meaningful increased apoptosis, including both early and late apoptosis (p < 0.001), suggesting a pivotal role in initiating programmed cell death by the apoptotic pathway. The analysis revealed that the metabolic activity of treated cancer cells was lower compared to those of the control group (p < 0.001).

Green Tea Leaves and Rosemary Extracts Selectively Induce Cell Death in Triple-Negative Breast Cancer Cells and Cancer Stem Cells and Enhance the Efficacy of Common Chemotherapeutics

While incredible medical advancements in chemotherapeutics development for cancer treatment have been made, the majority of these are not selective in their mechanism of action, leading to adverse effects. Given the systemic toxicity associated with these therapies, they are not well suited for long-term use. Natural health products, or NHPs, may provide a way to selectively target the oxidative and metabolic vulnerabilities in cancer cells. White tea (Camelia sinensis) and rosemary (Salvia rosmarinus) are two natural extracts that have been studied extensively for their medicinal properties. However, their anticancer activity and mechanism of action are yet to be fully elucidated. We have examined the extracts’ cancer cell-killing ability as well as their interactions with common chemotherapeutics in MDA-MB-231 cells, a triple-negative breast cancer cell line, in vitro. Cell death measurement, morphological and biochemical characterization of apoptotic cell death, mechanisms of action (mitochondrial depolarization and oxidative stress), and immunofluorescence assays to estimate the percentage of cancer stem cells (CSCs) were performed following treatment with Synthite tea extract (STE) and rosemary extract (RE), provided by Synthite Industries Limited alone and in combination with cisplatin and paclitaxel. The key findings in this study are that STE and RE alone demonstrated very efficient anticancer activity against TNBC, and more importantly, the administration of the extracts in conjunction with cisplatin and paclitaxel sensitizes cancer cells to achieve enhanced cell death. In addition, CSCs were found to be sensitive to treatment with STE alone and in combination with RE and exhibited greater sensitivity to combination therapies compared to chemotherapeutic alone. The significance of these observations is that STE and RE, well-tolerated NHPs, have the potential to enhance the efficacy of current chemotherapeutics when combined, as well as prevent relapse for TNBC.

Evaluation of BMP-2 as a differentiating and radiosensitizing agent for colorectal cancer stem cells.

Despite effective clinical responses, a large proportion of patients undergo resistance to radiotherapy. The low response rate to current treatments in different stages of colorectal cancer depends on the prominent role of stem cells in cancer. In the present study, the role of BMP-2 as an ionizing radiation-sensitive factor in colorectal cancer cells was investigated. A sphere formation assay was used for the enrichment of HCT-116 cancer stem cells (CSCs). The effects of combination therapy (BMP-2+ radiation) on DNA damage response (DDR), proliferation, and apoptosis were evaluated in HCT-116 and CSCs. Gene expressions of CSCs and epithelial-mesenchymal transition (EMT) markers were also evaluated. We found that the sphere formation assay showed a significant increase in the percentage of CSCs. Moreover, expression of CSCs markers, EMT-related genes, and DNA repair proteins significantly decreased in HCT-116 cells compared to the CSCs group after radiation. In addition, BMP-2 promoted the radiosensitivity of HCT-116 cells by decreasing the survival rate of the treated cells at 2, 4, and 6 Gy compared to the control group in HCT-116 cells. Our findings indicated that BMP-2 could affect numerous signaling pathways involved in radioresistance. Therefore, BMP-2 ‎ can be considered an appealing therapeutic target for the treatment of radioresistant human colorectal cancer.

Clinical Significance of Porphyromonas gingivalis Enriching Cancer Stem Cells by Inhibiting Programmed Cell Death Factor 4 in Esophageal Squamous Cell Carcinoma.

Studies have confirmed that the colonization of Porphyromonas gingivalis (Pg) could promote the malignant evolution of esophageal squamous cell carcinoma (ESCC). Since pathogenic microorganisms can promote malignant tumor proliferation by inhibiting programmed cell death factor 4 (PDCD4) and the decrease of PDCD4 activity can enhance the stemness of cancer cells, we here investigated the functional mechanism by which Pg promoted ESCC chemoresistance and malignancy through inhibiting PDCD4 and enriching cancer stem cells (CSCs). The effects of Pg and PDCD4 on CSCs, chemoresistance and malignancy of ESCC cells were evaluated by in vitro studies. The expression of Pg, PDCD4, and ALDH1 in ESCC tissues were detected by IHC, and the correlations between each index and postoperative survival of ESCC patients were analyzed. The results showed that Pg could inhibit PDCD4 expression and lead to CSCs enrichment in ESCC cells. After eliminating Pg, the expression of PDCD4 was upregulated, the percentage of CSCs, chemoresistance and malignancy were decreased. ESCC patients with Pg-positive, PDCD4-negative, and ALDH1-positive have a significant shorter survival. This study proved that eliminating Pg and blocking CSCs enrichment caused by decreasing PDCD4 activity may provide a new strategy for ESCC treatment.

Correlative Raman-Electron-Light (CREL) Microscopy Analysis of Lipid Droplets in Melanoma Cancer Stem Cells.

Among all neoplasms, melanoma is characterized by a very high percentage of cancer stem cells (CSCs). Several markers have been proposed for their identification, and lipid droplets (LDs) are among them. Different techniques are used for their characterization such as mass spectrometry, imaging techniques, and vibrational spectroscopies. Some emerging experimental approaches for the study of LDs are represented by correlative light-electron microscopy and by correlative Raman imaging-scanning electron microscopy (SEM). Based on these scientific approaches, we developed a novel methodology (CREL) by combining Raman micro-spectroscopy, confocal fluorescence microscopy, and SEM coupled with an energy-dispersive X-ray spectroscopy module. This procedure correlated cellular morphology, chemical properties, and spatial distribution from the same region of interest, and in this work, we presented the application of CREL for the analysis of LDs within patient-derived melanoma CSCs (MCSCs).

Reprograming immune microenvironment modulates CD47 cancer stem cells in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the most common type of liver cancer. There are different therapeutic approaches to cancer eradication such as chemotherapy, radiotherapy, and surgery. The fuel for treatment resistance is heterogeneity, which also has significant effects on cancer therapies and biomarker research. One of the most common causes of cancer chemoresistance and relapse is the presence and percentage of cancer stem cells (CSCs), among them CD47+ CSCs. Besides, the change in the tumor microenvironment (TME) stands as one of the main factors for the failure of chemotherapeutic protocols. The current review aims to focus on how the change in immune mediators such as TGF-β, IL-10, IL-17, IDO, Gal-1, PD-L1, and CTLA-4 affect CD47+ CSCs in HCC and thus open a new era towards developing new approaches for prevention of HCC relapse and stemness through different immune modulation approaches. Then we investigate some drugs that have a dual effect on both TME and CD47 CSCs and thus the best choice in comorbidities.

High percentage of Cancer Stem cells in metastatic locations: Upregulation of cicBIRC6 in highly metastatic breast Cancer Subline.

Metastasis is a devastating complication of breast cancer. Cancer relapse and metastasis are associated with cancer stem cells. CicBIRC6 is a circular RNA that is proposed to be involved in the stemness of stem cells. In breast cancer, metastatic tumor cells have higher stem cell properties. In the present study, we evaluate the expression of cicBIRC6 in these cells. After the development of a syngeneic animal model of TNBC, primary breast cancer cells named 4T1T were isolated from the tumor mass. Highly metastatic tumor cells named 4T1B and 4T1L were isolated and expanded from brain metastasis lesions and lungs of cancerous mice respectively. Sphere formation ability in metastatic and primary tumor cells was evaluated separately. The quantitative real-time polymerase chain reaction was performed to analyze the expression of cicBIRC6 in primary and metastatic tumor cells. Our data revealed that, sphere formation ability among metastatic tumor cells was significantly higher. Surprisingly expression of cicBIRC6 was significantly upregulated in these metastatic tumor cells. In comparison with 4T1T, cicBIRC6 was upregulated 5.7 and 3.5 times in 4T1B and 4T1L respectively. These findings provided important insights regarding the molecular properties of metastatic tumor cells and can be used for designing a targeted therapeutic strategy in combat with these cells.

Novel Thieno [2,3-b]pyridine Anticancer Compound Lowers Cancer Stem Cell Fraction Inducing Shift of Lipid to Glucose Metabolism.

Due to the role of cancer stem cells (CSCs) in tumor resistance and glycosphingolipid (GSL) involvement in tumor pathogenesis, we investigated the effect of a newly synthesized compound (3-amino-N-(3-chloro-2-methylphenyl)-5-oxo-5,6,7,8-tetrahydrothieno[2,3-b]quinoline-2-carboxamide 1 on the percentage of CSCs and the expression of six GSLs on CSCs and non-CSCs on breast cancer cell lines (MDA-MB-231 and MCF-7). We also investigated the effect of 1 on the metabolic profile of these cell lines. The MTT assay was used for cytotoxicity determination. Apoptosis and expression of GSLs were assessed by flow cytometry. A GC–MS-coupled system was used for the separation and identification of metabolites. Compound 1 was cytotoxic for both cell lines, and the majority of cells died by treatment-induced apoptosis. The percentage of CSCs was significantly lower in the MDA-MB-231 cell line. Treatment with 1 caused a decrease of CSC IV6Neu5Ac-nLc4Cer+ MDA-MB-231 cells. In the MCF-7 cell line, the percentage of GalNAc-GM1b+ CSCs was increased, while the expression of Gg3Cer was decreased in both CSC and non-CSC. Twenty-one metabolites were identified by metabolic profiling. The major impact of the treatment was in glycolysis/gluconeogenesis, pyruvate and inositol metabolism. Compound 1 exhibited higher potency in MBA-MB-231 cells, and it deserves further examination.

Immunological microenvironment in colon cancer patients with different phenotypes of cancer stem cells.

e15503 Background: The purpose of this study was to analyze the effect of the CD44+ and CD133+ co-expression in cancer stem cells (CSCs) on lymphocytic microenvironment of colon cancer (CC). Methods: 200 CC patients received surgery as the first stage of treatment. The percentage of CSCs with the expression of CD44+ and/or CD133+ markers was studied in the tumor homogenates by flow cytometry, as well as some indicators of local immunity (CD3+, CD4+, CD8+, T regs (CD4+CD25+CD127dim), CD19+, PD-1, PD-L1, Th0, Tm, CD16/56+ and immunophenotypic characteristics of tumor cells (PD-L1, MHC-ABC). Results: Gradation depending on the absence or presence of co-expression of CSC markers on tumor cells allowed identification of 11 statistically significant differences out of 17 studied parameters of tumor cells and their lymphocytic microenvironment. Co-expression of CSC markers was accompanied by higher percentage of T regs (7.3±0.4 versus 5.3±0.5%), together with lower levels of CD4+ cells. At the same time, a higher content of the total number of T-lymphocytes was noted due to CD8+ with an increase in the percentage of memory T cells and a decline in naive T lymphocytes within this subpopulation. In addition, the co-expression of CSC markers was accompanied by a lower content of PD-L1 (34.3±3.0 vs. 42.9±2.5%) on lymphocytes and its higher content on tumor cells (10.6±1.5 vs. 4.1±0.8%), while the PD-1 expression on lymphocytes was higher (38.4±3.7 versus 22.3±2.9%). The presence of CD44+CD133+ CSCs was also accompanied by lower percentage of tumor cells expressing MHC class I (60.4±4.9 vs. 79.3±7.6%), which characterized the inhibition of recognition processes, and increased levels of CD8+, perhaps, should be considered as compensatory. Conclusions: The lymphocytic microenvironment of CC in the presence of CSCs with the CD44+CD133+ immunophenotype seems to be more immunosuppressive, according to the increase in the local content of T regs and the decrease in MHC-ABC expression. Higher expression of PD-L1 on tumor cells and PD-1 on lymphocytes allows activation of the PD-1/PD-L1 interaction, which enhances the immunosuppressive and growth-stimulating properties of the tumor microenvironment, but at the same time, makes tumor cells adequate targets for immunotherapy with immune checkpoint inhibitors.

A Descriptive Study of the Physical Direct Interaction between Adipose Tissue-Mesenchymal Stem Cells and Colo 205 Cells: Impact on Cancer Cells Stemness, and Intracellular Reactive Oxygen Species Levels.

Background:Mesenchymal stem cells (MSCs) are widely used in clinical research to treat a wild spectrum of diseases due to their homing ability to damaged tissues, self-renewal capacity, and differentiation ability into various types of cells. In this research, we are describing the physical direct interaction between AT-MSCs and colon cancer cells, its impact on the stemness of colon cancer cells, along with the levels of intracellular Reactive Oxygen Species (ROS) levels in both types of cells. Methods:Adipose-tissue mesenchymal stem cells (AT-MSCs) were characterized by the means of MSCs classical markers expression using flow cytometry, and multilineage differentiation through osteogenic and adipogenic differentiation. MSCs and colo205 cells were cocultured in monolayer and 3D techniques in a ratio of 1:3 for 72 hours without media exchange and compared to monocultured cells. The physical direct interaction of cells in adhered culture and spheroids formation in ULA plates was observed using a light-inverted microscope. MSCs classical markers and cancer stem cells (CSCs) associated surface proteins were quantified in MSCs and colo205 cells. Intracellular ROS level was measured in both cell types. Surface protein and intracellular ROS quantification were carried out using flow cytometry. Results:CRC cells (colo205 cells) utilized MSCs as a feeder layer to grow and generate spheroids. The interaction increased the percentage of CSCs in colo205 population which was attributed to the increased expression of CD133, and reduced the levels of intracellular ROS in MSCs. Results indicated that MSCs support the growth, spheriod formation, and the stemness of colon cancer cells, while reducing the levels of intracellular ROS in MSCs.

Endothelin-1 as a Mediator of Heme Oxygenase-1-Induced Stemness in Colorectal Cancer: Influence of p53.

Heme oxygenase-1 (HO-1) is an antioxidant protein implicated in tumor progression, metastasis, and resistance to therapy. Elevated HO-1 expression is associated with stemness in several types of cancer, although this aspect has not yet been studied in colorectal cancer (CRC). Using an in vitro model, we demonstrated that HO-1 overexpression regulates stemness and resistance to 5-FU treatment, regardless of p53. In samples from CRC patients, HO-1 and endothelin converting enzyme-1 (ECE-1) expression correlated significantly, and p53 had no influence on this result. Carbon monoxide (CO) activated the ECE-1/endothelin-1 (ET-1) pathway, which could account for the protumoral effects of HO-1 in p53 wild-type cells, as demonstrated after treatment with bosentan (an antagonist of both ETRA and ETRB endothelin-1 receptors). Surprisingly, in cells with a non-active p53 or a mutated p53 with gain-of-function, ECE-1-produced ET-1 acted as a protective molecule, since treatment with bosentan led to increased efficiency for spheres formation and percentage of cancer stem cells (CSCs) markers. In these cells, HO-1 could activate or inactivate certain unknown routes that could induce these contrary responses after treatment with bosentan in our cell model. However more research is warranted to confirm these results. Patients carrying tumors with a high expression of both HO-1 and ECE-1 and a non-wild-type p53 should be considered for HO-1 based-therapies instead of ET-1 antagonists-based ones.

Amount of cancer stem cells in tumors of patients with ovarian cancer with different responses to platinum-containing chemotherapy.

e17527 Background: Resistance to chemotherapy is a complex problem in the treatment of patients with ovarian cancer (OC), and this phenomenon is associated, among other things, with the presence of cancer stem cells (CSCs). The purpose of the study was to determine the amount of CSCs in tumors of OC patients with different responses to chemotherapy they receive. Methods: Samples of ovarian tumors were obtained from 100 patients (aged 29-79 years) with advanced ovarian cancer stage IIIC-IV with/without ascites. All patients recruited in 2016-2020 received standard combination treatment with surgery and platinum-containing polychemotherapy (Pt CT). Based on the results of neoadjuvant Pt CT, patients were divided into groups: patients with stabilization or progression–group 1 “without effect”; patients with complete/partial regression–group 2 with positive effect. All patients gave their informed consent for the study. Cell suspension obtained from the tumor fragments was processed using monoclonal antibodies labeled with various fluorochromes: CD45-APC-Cy7, CD44-FITС, CD133–РЕ according to the manufacturer's instructions (BD, USA). The percentage of CSCs was determined using the FACS Canto II flow cytometer (BD, USA). The amount of cells with CSC markers (CD44+, CD133+, CD44+CD133+) was calculated as a percentage from the total amount of CD45--cells. Statistics: STATISTICA 13 (StatSoftInc., USA). Results were presented as Me (LQ; UQ). The significance of differences was assessed using the Mann-Whitney test (the differences were considered significant at p&lt;0.05). Results: The amount of CD45- _cells, as well as CD45-CD44+ cells, in OC tumors did not differ between patients of groups 1 and 2: 79.0 (72.1; 85.9) vs. 82.8 (76.7; 89.0), and 6.2 (3.3; 9.1) vs. 6.6 (3.5; 9.8), respectively. The percentage of cancer cells with the CD45-CD133+ phenotype in group 2 was significantly lower than in group 1: by 52% (p≤0.05), 3.2 (2.4; 3.9) vs. 6.7 (3.8; 9.6), respectively. The amount of CD45-CD44+CD133- CSCs in tumors in group 1 was lower than in group 2: by 82% (p≤0.05), 0.6 (0.3; 0.7) vs. 3.3 (1.8; 4.7), respectively. Conclusions: The results demonstrated certain differences in the distribution of CSCs in tumors of OC patients with different sensitivity to chemotherapy, which may be one of the factors determining the treatment outcomes.

The diverse metabolic heterogeneity of stem cells in a BRCA+/-breast cancer population.

Breast cancers are very heterogeneous tissues constituted by epithelial cancer cells and an abnormal tumor microenvironment – cancer-associated fibroblasts (CAFs), activated adipocytes, mesenchymal stem cells (MSCs), and others. The aim of the study is to cancer cells and their microenvironment, which behave like a complex and heterogeneous metabolic ecosystem, where cancer cells can reprogram their metabolism as a result of interaction with the components of the microenvironment. The study was based on cancer stem cells (CSC) that were isolated from breast tumors by magnetic separation (AutoMACS). We used spectrophotometric methods for the measurement of aldehyde dehydrogenase (ALDH) enzymatic activity. For these experiments, we used breast cancer and normal stem cell lines. Analyses showed that the proportion of BRCA+ CSC cells was in accordance with the relatively low percentages of CSCs in BRCA+ tumors. ALHD was significantly higher in the CSCs-high BRCA+ breast cancer and CSCs-low BRCA- breast cancer cells, compared with the CSCs-low BRCA+ breast cancer. Breast cancer from BRCA mutation carriers harbor more “high-energy” cell sub-populations than “low-energy” and have their more aggressive phenotype. Key oncogenic pathways known to be dysregulated in breast cancer also regulate stem-cell behavior.

Copper-64 Chloride Exhibits Therapeutic Potential in Three-Dimensional Cellular Models of Prostate Cancer.

Prostate cancer (PCa) is the second most common cancer type in men, and in advanced metastatic stages is considerable incurable. This justifies the need for efficient early diagnostic methods and novel therapies, particularly radiopharmaceuticals with the potential for simultaneous diagnosis and therapy (theranostics). We have previously demonstrated, using monolayer-cultured cells, that copper-64 chloride, a promising theranostic agent for PCa, has the potential to induce significant damage in cancer cells while having minimal side effects in healthy tissues. Here, we further explored this compound for its theranostic applications using more advanced PCa cellular models, specifically multicellular spheroids. Namely, we evaluated the cellular uptake of 64CuCl2 in three human PCa spheroids (derived from 22RV1, DU145, and LNCaP cells), and characterized the growth profile and viability of those spheroids as well as the clonogenic capacity of spheroid-derived cells after exposure to 64CuCl2. Furthermore, the populations of cancer stem cells (CSCs), known to be important for cancer resistance and recurrence, present in the spheroid models were also evaluated using two different markers (CD44 and CD117). 64CuCl2 was found to have significant detrimental effects in spheroids and spheroid-derived cells, being able to reduce their growth and impair the viability and reproductive ability of spheroids from both castration-resistant (22RV1 and DU145) and hormone-naïve PCa (LNCaP). Interestingly, resistance to 64CuCl2 treatment seemed to be related with the presence of a CSC population, since the most resistant spheroids, derived from the DU145 cell line, had the highest initial percentage of CSCs among the three cell lines under study. Altogether, these results clearly highlight the theranostic potential of 64CuCl2.

TrkB-Targeted Therapy for Mucoepidermoid Carcinoma.

The brain-derived neurotrophic factor (BDNF)/tyrosine receptor kinase B (TrkB) pathway was previously associated with key oncogenic outcomes in a number of adenocarcinomas. The aim of our study was to determine the role of this pathway in mucoepidermoid carcinoma (MEC). Three MEC cell lines (UM-HMC-2, H253 and H292) were exposed to Cisplatin, the TrkB inhibitor, ANA-12 and a combination of these drugs. Ultrastructural changes were assessed through transmission electron microscopy; scratch and Transwell assays were used to assess migration and invasion; and a clonogenic assay and spheroid-forming assay allowed assessment of survival and percentage of cancer stem cells (CSC). Changes in cell ultrastructure demonstrated Cisplatin cytotoxicity, while the effects of ANA-12 were less pronounced. Both drugs, used individually and in combination, delayed MEC cell migration, invasion and survival. ANA-12 significantly reduced the number of CSC, but the Cisplatin effect was greater, almost eliminating this cell population in all MEC cell lines. Interestingly, the spheroid forming capacity recovered, following the combination therapy, as compared to Cisplatin alone. Our studies allowed us to conclude that the TrkB inhibition, efficiently impaired MEC cell migration, invasion and survival in vitro, however, the decrease in CSC number, following the combined treatment of ANA-12 and Cisplatin, was less than that seen with Cisplatin alone; this represents a limiting factor.

High percentage of cancer stem cells in metastatic locations; a comment on a claim “variation in cancer risk among tissues can be explained by the number of stem cell divisions”

Metastasis is the major cause of cancer-related deaths. Cancer relapse and metastasis are associated with a part of cancer cells with stem cell properties. These cancer stem cells (CSCs) are resistant to treatments. In a recent survey, we observed that the population of cancer stem-like cells among metastatic tumor cells was significantly higher than that among the primary tumor cells. This high percentage can partly explain the reasons for chemoresistance and relapse in metastatic cancers. Analysis of the role of CSCs in metastasis has been mainly conceptual and speculative, and the reasons for a higher number of CSCs in the metastatic loci are questionable. Tomasetti and Vogelstein’s claim can partly answer the question. They postulated that the proliferation rate of normal stem cells in some tissue is greater than that of other tissues, and accordingly, the incidence of cancer in these tissues is high. In compliance with CSCs paradigm, resident normal stem cells of tissues are the most probable source of CSCs. After homing of metastatic cancer cells in a tissue with high rate of normal stem cell proliferation, there is a big opportunity for cancer cells to convert normal stem cells to cancer stem cells. This is the powerful effect of cancerous microenvironment on resident stem cells of tissue. Therefore, in metastatic cancers, the number of CSCs in primary tumor or in each metastatic location is relevant to the proliferation rate of resident normal stem cells of the location. This concept is a confirmation of Tomasetti and Vogelstein’s claim and can answer some fundamental questions about metastasis process.

Glycosphingolipid expression at breast cancer stem cells after novel thieno[2,3-b]pyridine anticancer compound treatment

Glycosphingolipid expression differs between human breast cancer stem cells (CSC) and cancer non-stem cells (non-CSC). We performed studies of viability, type of cell death, cancer stem cell percent and glycosphingolipid expression on CSC and non-CSC after treatment of MDA-MB-231 and MDA-MB-453 triple-negative breast cancer cells with a newly developed thienopyridine anticancer compound (3-amino-N-(3-chloro-2-methylphenyl)-5-oxo-5,6,7,8-tetrahydrothieno[2,3-b]quinoline-2-carboxamide, 1). Compound 1 was cytotoxic for both breast cancer cell lines and the majority of cells died by treatment-induced apoptosis. The percent of cancer stem cells and number of formed mammospheres was significantly lower. Glycosphingolipids IV6Neu5Ac-nLc4Cer and GalNAc-GM1b (IV3Neu5Ac-Gg5Cer) not reported previously, were identified in both CSCs and non-CSCs. IV6Neu5Ac-nLc4Cer had increased expression in both CSCs and non-CSCs of both cell lines after the treatment with 1, while GM3 (II3Neu5Ac-LacCer) had increased expression only on both cell subpopulations in MDA-MB-231 cell line. GalNAc-GM1b, Gb4Cer (GalNAcβ1-3Galα1-4Galβ1-4Glcβ1-1Cer) and GM2 (II3Neu5Ac-GalNAcβ1-4Galβ1-4Glcβ1-1Cer) were increased only in CSCs of both cell lines while GD3 was decreased in CSC of MDA-MB-231 cell line. Due to its effect in reducing the percentage of cancer stem cells and number of mammospheres, and its influence upon several glycosphingolipid expressions, it can be concluded that compound 1 deserves attention as a potential new drug for triple-negative breast cancer therapy.

Inhibitory effect of melatonin on hypoxia-induced vasculogenic mimicry via suppressing epithelial-mesenchymal transition (EMT) in breast cancer stem cells.

Vasculogenic mimicry (VM) play an important role in breast cancer metastasis and anti- angiogenic drugs resistance. Hypoxia, the epithelial-mesenchymal transition (EMT), and cancer stem cells (CSCs) are known as essential factors for VM formation. Also, melatonin is an amino acid-derived hormone with many anti-tumor effects. Despite the antitumor effects of melatonin, its effect on VM formation in breast cancer has not been considered yet, so we investigated the effect of melatonin on VM formation through EMT process under hypoxia conditions in breast CSCs. The CSCs percentage and VM formation were determined in MCF-7 and MDA-MB-231, respectively. Also, analysis of HIF-1α expression under hypoxia in MDA-MB-231 and MCF-7 cell lines was performed using Western blot. The effect of melatonin on the VM formation, invasion, and migration was also investigated. Moreover, the effect of melatonin on the expression EMT markers was evaluated. CD44+ CD24-phenotype as CSCs marker in MDA-MB-231 cell line, was 80.8%, while it was 11.1% in MCF-7 cell line. HIF-1α expression was up-regulated in the VM-positive breast cancer cell line MDA-MB-231, and consequently, affected the expression of the EMT markers E-cadherin, vimentin, snail, and MMP9. Melatonin had significant effect on EMT and formations of VM in breast CSCs. Melatonin could prevent the formation of VM by affecting the important molecules involved in the formation of VM structures and the EMT. Moreover, our data clearly showed that, melatonin represents molecule with significant anti-cancer activities that may potentially optimize the management of breast cancer through the overcoming drug resistance in anti-angiogenic drugs.

The impact of photobiomodulation therapy on the biology and behavior of head and neck squamous cell carcinomas cell lines

Photobiomodulation therapy (PBMT) is an emerging therapeutic modality designed to prevent and treat chemotherapy-driven oral mucositis (OM). However, the response of tumor cells to the effects of PBMT remains poorly understood. Our study explores the effects of PBMT in head and neck squamous cell carcinoma (HNSCC) based on cellular proliferation, migration, and survival of tumor cells and its population of cancer stem cells (CSC). We explored the behavior of two HNSCC cell lines (HN6 and HN13) under two distinct conditions, a physiological growing condition (10% FBS), and under stress growing condition (2% FBS) prior to irradiation using diode laser (InGaAlP; MM Optics, São Carlos, SP, Brazil). Diode laser (660 nm) was applied with a power of 100 mW delivering a total energy per point of 0.24 J. MTT and wound healing test (scratch assay) were performed to evaluate, respectively, proliferation and migration of tumor cells. Clonogenic and spheres formation assays were also performed to evaluate the survival and percentage of CSC upon irradiation. Overall, we observed that PBMT does not exacerbate the behavior of HNSCC. We could only observe a decrease in cellular proliferation of one cell line (HN6) when cultured under nutritional stress conditions (p < .05). There were no significant differences between the control and the PBMT groups regarding cell migration, survival and the percentage of CSC. Collectively, our results suggest that in vitro administration of PBMT to HNSCC does not modify the behavior of tumor cells.

The Missing Lnc: The Potential of Targeting Triple-Negative Breast Cancer and Cancer Stem Cells by Inhibiting Long Non-Coding RNAs.

Treatment decisions for breast cancer are based on staging and hormone receptor expression and include chemotherapies and endocrine therapy. While effective in many cases, some breast cancers are resistant to therapy, metastasize and recur, leading to eventual death. Higher percentages of tumor-initiating cancer stem cells (CSCs) may contribute to the increased aggressiveness, chemoresistance, and worse outcomes among breast cancer. This may be particularly true in triple-negative breast cancers (TNBCs) which have higher percentages of CSCs and are associated with worse outcomes. In recent years, increasing numbers of long non-coding RNAs (lncRNAs) have been identified as playing an important role in breast cancer progression and some of these have been specifically associated within the CSC populations of breast cancers. LncRNAs are non-protein-coding transcripts greater than 200 nucleotides which can have critical functions in gene expression regulation. The preclinical evidence regarding lncRNA antagonists for the treatment of cancer is promising and therefore, presents a potential novel approach for treating breast cancer and targeting therapy-resistant CSCs within these tumors. Herein, we summarize the lncRNAs that have been identified as functionally relevant in breast CSCs. Furthermore, our review of the literature and analysis of patient datasets has revealed that many of these breast CSC-associated lncRNAs are also enriched in TNBC. Together, this suggests that these lncRNAs may be playing a particularly important role in TNBC. Thus, certain breast cancer-promoting/CSC-associated lncRNAs could be targeted in the treatment of TNBCs and the CSCs within these tumors should be susceptible to anti-lncRNA therapy.