Behavior Of Cancer Stem Cells Research Articles

Live tumor imaging shows macrophage\xa0induction and TMEM-mediated enrichment of cancer stem cells during metastatic dissemination

Cancer stem cells (CSCs) play an important role during metastasis, but the dynamic behavior and induction mechanisms of CSCs are not well understood. Here, we employ high-resolution intravital microscopy using a CSC biosensor to directly observe CSCs in live mice with mammary tumors. CSCs display the slow-migratory, invadopod-rich phenotype that is the hallmark of disseminating tumor cells. CSCs are enriched near macrophages, particularly near macrophage-containing intravasation sites called Tumor Microenvironment of Metastasis (TMEM) doorways. Substantial enrichment of CSCs occurs on association with TMEM doorways, contributing to the finding that CSCs represent >60% of circulating tumor cells. Mechanistically, stemness is induced in non-stem cancer cells upon their direct contact with macrophages via Notch-Jagged signaling. In breast cancers from patients, the density of TMEM doorways correlates with the proportion of cancer cells expressing stem cell markers, indicating that in human breast cancer TMEM doorways are not only cancer cell intravasation portals but also CSC programming sites.

Mesenchymal stem cell-derived exosomes block malignant behaviors of hepatocellular carcinoma stem cells through a lncRNA C5orf66-AS1/microRNA-127-3p/DUSP1/ERK axis.

Mesenchymal stem cell (MSCs)-derived exosomes have been frequently used as useful tools in disease control. This research aimed to study the function of MSC-derived exosomes (Exo) in the stemness of cancer stem cells (CSCs) of hepatocellular carcinoma (HCC) and the molecular mechanism. Exo from the procured human bone marrow-MSCs were extracted and identified. CSCs from HCC cell lines were collected. The CSCs were treated with Exo, and then the proliferation, migration, invasion, angiogenesis-stimulating and self-renewal abilities of the Hep3B-CSCs and HuH7-CSCs were significantly reduced. C5orf66-AS1 was found as the most upregulated long noncoding RNAs (lncRNAs) in CSCs after Exo treatment. The integrated bioinformatic analyses and luciferase assays suggested that C5orf66-AS1 upregulated DUSP1 expression through sequestering microRNA-127-3p (miR-127-3p). Either artificial overexpression of miR-127-3p or silencing of DUSP1 blocked the inhibitory functions of Exo in the CSCs. DUSP1 inhibition increased the phosphorylation of ERK. Similar results were reproduced in vivo where Exo reduced the growth of xenograft formed by CSCs in nude mice, and this reduction was blocked upon miR-127-3p overexpression or DUSP1 silencing. To conclude, this research reported that MSC-derived Exo block malignant behaviors of HCC-sourced CSCs through a C5orf66-AS1/miR-127-3p/DUSP1/ERK axis.

Cancer Stem Cells in Tumor Modeling: Challenges and Future Directions.

Microfluidic tumors-on-chips models have revolutionized anticancer therapeutic research by creating an ideal microenvironment for cancer cells. The tumor microenvironment (TME) includes various cell types and cancer stem cells (CSCs), which are postulated to regulate the growth, invasion, and migratory behavior of tumor cells. In this review, the biological niches of the TME and cancer cell behavior focusing on the behavior of CSCs are summarized. Conventional cancer models such as three-dimensional cultures and organoid models are reviewed. Opportunities for the incorporation of CSCs with tumors-on-chips are then discussed for creating tumor invasion models. Such models will represent a paradigm shift in the cancer community by allowing oncologists and clinicians to predict better which cancer patients will benefit from chemotherapy treatments.

The C-X-C Motif Chemokine Ligand 1 Sustains Breast Cancer Stem Cell Self-Renewal and Promotes Tumor Progression and Immune Escape Programs.

Breast cancer (BC) mortality is mainly due to metastatic disease, which is primarily driven by cancer stem cells (CSC). The chemokine C-X-C motif ligand-1 (CXCL1) is involved in BC metastasis, but the question of whether it regulates breast cancer stem cell (BCSC) behavior is yet to be explored. Here, we demonstrate that BCSCs express CXCR2 and produce CXCL1, which stimulates their proliferation and self-renewal, and that CXCL1 blockade inhibits both BCSC proliferation and mammosphere formation efficiency. CXCL1 amplifies its own production and remarkably induces both tumor-promoting and immunosuppressive factors, including SPP1/OPN, ACKR3/CXCR7, TLR4, TNFSF10/TRAIL and CCL18 and, to a lesser extent, immunostimulatory cytokines, including IL15, while it downregulates CCL2, CCL28, and CXCR4. CXCL1 downregulates TWIST2 and SNAI2, while it boosts TWIST1 expression in association with the loss of E-Cadherin, ultimately promoting BCSC epithelial-mesenchymal transition. Bioinformatic analyses of transcriptional data obtained from BC samples of 1,084 patients, reveals that CXCL1 expressing BCs mostly belong to the Triple-Negative (TN) subtype, and that BC expression of CXCL1 strongly correlates with that of pro-angiogenic and cancer promoting genes, such as CXCL2-3-5-6, FGFBP1, BCL11A, PI3, B3GNT5, BBOX1, and PTX3, suggesting that the CXCL1 signaling cascade is part of a broader tumor-promoting signaling network. Our findings reveal that CXCL1 functions as an autocrine growth factor for BCSCs and elicits primarily tumor progression and immune escape programs. Targeting the CXCL1/CXCR2 axis could restrain the BCSC compartment and improve the treatment of aggressive BC.

Emerging Role of MicroRNA-200 Family in Dentistry.

MicroRNAs (miRNAs) are endogenous non-coding RNAs ~22 nucleotides in length, which have been shown to participate in various biological processes. As one of the most researched miRNAs, the miR-200 family has been found to regulate several factors that are associated with the epithelial to mesenchymal transition (EMT) and cancer stem cells (CSCs) behavior. In this review, we briefly summarize the background of the miR-200 family and their implication in various dental diseases. We focus on the expression changes, biological functions, and clinical significance of the miR-200 family in oral cancer; periodontitis; oral potentially malignant disorder; gingival overgrowth; and other periodontal diseases. Additionally, we discuss the use of the miR-200 family as molecular biomarkers for diagnosis, prognostic, and therapeutic application.

Evidence of Reelin Signaling in GBM and Its Derived Cancer Stem Cells.

Glioblastoma (GBM) is the most aggressive and malignant form of primary brain cancer, characterized by an overall survival time ranging from 12 to 18 months. Despite the progress in the clinical treatment and the growing number of experimental data aimed at investigating the molecular bases of GBM development, the disease remains characterized by a poor prognosis. Recent studies have proposed the existence of a population of GBM cancer stem cells (CSCs) endowed with self-renewal capability and a high tumorigenic potential that are believed to be responsible for the resistance against common chemotherapy and radiotherapy treatments. Reelin is a large secreted extracellular matrix glycoprotein, which contributes to positioning, migration, and laminar organization of several central nervous system structures during brain development. Mutations of the reelin gene have been linked to disorganization of brain structures during development and behavioral anomalies. In this study, we explored the expression of reelin in GBM and its related peritumoral tissue and performed the same analysis in CSCs isolated from both GBM (GCSCs) and peritumoral tissue (PCSCs) of human patients. Our findings reveal (i) the higher expression of reelin in GBM compared to the peritumoral tissue by immunohistochemical analysis, (ii) the mRNA expression of both reelin and its adaptor molecule Dab1 in either CSC subtypes, although at a different extent; and (iii) the contribution of CSCs-derived reelin in the migration of human primary GBM cell line U87MG. Taken together, our data indicate that the expression of reelin in GBM may represent a potential contribution to the regulation of GBM cancer stem cells behavior, further stimulating the interest on the reelin pathway as a potential target for GBM treatment.

Unraveling the origin of glucose mediated disparate proliferation dynamics of cancer stem cells

Cancer stem cells (CSCs) often switch on their self-renewal programming aggressively to cause a relapse of cancer. Intriguingly, glucose triggers the proliferation propensities in CSCs by controlling the expression of the key transcription factor-like Nanog. However, the factors that critically govern this glucose-stimulated proliferation dynamics of CSCs remain elusive. Herein, by proposing a mathematical model of glucose-mediated Nanog regulation, we showed that the differential proliferation behavior of CSCs and cell-type similar to CSCs can be explained by considering the experimentally observed varied expression levels of key positive (STAT3) and negative (p53) regulators of Nanog. Our model reconciles various experimental observations and predicts ways to fine-tune the proliferation dynamics of these cell types in a context-dependent manner. In future, these modeling insights will be useful in developing improved therapeutic strategies to get rid of harmful CSCs.

Microgravity, Stem Cells, and Cancer: A New Hope for Cancer Treatment.

Humans are integrated with the environment where they live. Gravitational force plays an important role in shaping the universe, lives, and even cellular biological processes. Research in the last 40 years has shown how exposure to microgravity changes biological processes. Microgravity has been shown to have significant effects on cellular proliferation, invasion, apoptosis, migration, and gene expression, specifically in tumor cells, and these effects may also exist in stem and cancer stem cells. It has also been shown that microgravity changes the effects of chemotherapeutic drugs. Although studies have been carried out in a simulated microgravity environment in cell culture lines, there are few animal experiments or true microgravity studies. Cancer remains one of the most significant problems worldwide. Despite advances in medical science, no definitive strategies have been found for the prevention of cancer formation or to inform treatment. Thus, the microgravity environment is a potential new therapeutic strategy for future cancer treatment. This review will focus on current knowledge on the impact of the microgravity environment on cancer cells, stem cells, and the biological behavior of cancer stem cells.

Apatinib Inhibits Stem Properties and Malignant Biological Behaviors of Breast Cancer Stem Cells by Blocking Wnt/β-catenin Signal Pathway through Downregulating LncRNA ROR

Cancer stem cells could influence tumor recurrence and metastasis. To develop a new effective treatment modality targeting breast cancer stem cells (BCSCs) and to explore the role of Apatinib in BCSCs. BCSCs were isolated from MDA-MB-231 cells by the immune magnetic beads method. BCSCs were treated with Apatinib, lentiviral plasmids (lncRNA ROR), and iCRT-3 (Wnt pathway inhibitors). Viability, colony numbers, sphere numbers, apoptosis, migration, invasion of BCSCs were detected by MTT, colony formation, tumorsphere, flow cytometry, wound-healing, transwell assays, respectively. The expressions of markers (ABCG2, CD44, CD90, and CD24), epithelial-mesenchymal transition (EMT)-related molecules (Ecadherin, N-cadherin, Vimentin, MMP-2, MMP-9), and Wnt/β-catenin pathway-related proteins (Wnt3a, Wnt5a, β-catenin) in breast cancer stem cells were determined by performing Western blot and qRT-PCR analysis. Apatinib decreased the viability and colony numbers of BCSCs in a concentration-dependent manner, and it also reduced sphere numbers, suppressed migration, invasion and lncRNA ROR expression, and induced apoptosis of BCSCs. However, these results were partially reversed by lncRNA ROR overexpression. Apatinib suppressed stem property, EMT process, and Wnt/β-catenin pathway in BCSCs, which was partially reversed by lncRNA ROR overexpression. Moreover, lncRNA ROR overexpression increased the colony and sphere numbers and promoted the cell viability, apoptosis inhibition, migration, and invasion of BCSCs, but these effects were partially reversed by iCRT-3. LncRNA ROR overexpression increased the stem property, EMT process, and Wnt/β-catenin pathway, which were partially counteracted by iCRT-3. Apatinib inhibited stem property and malignant biological behaviors of BCSCs by blocking the Wnt/β-catenin signal pathway through down-regulating lncRNA ROR.

Understanding the influence of substrate when growing tumorspheres

BackgroundCancer stem cells are important for the development of many solid tumors. These cells receive promoting and inhibitory signals that depend on the nature of their environment (their niche) and determine cell dynamics. Mechanical stresses are crucial to the initiation and interpretation of these signals.MethodsA two-population mathematical model of tumorsphere growth is used to interpret the results of a series of experiments recently carried out in Tianjin, China, and extract information about the intraspecific and interspecific interactions between cancer stem cell and differentiated cancer cell populations.ResultsThe model allows us to reconstruct the time evolution of the cancer stem cell fraction, which was not directly measured. We find that, in the presence of stem cell growth factors, the interspecific cooperation between cancer stem cells and differentiated cancer cells induces a positive feedback loop that determines growth, independently of substrate hardness. In a frustrated attempt to reconstitute the stem cell niche, the number of cancer stem cells increases continuously with a reproduction rate that is enhanced by a hard substrate. For growth on soft agar, intraspecific interactions are always inhibitory, but on hard agar the interactions between stem cells are collaborative while those between differentiated cells are strongly inhibitory. Evidence also suggests that a hard substrate brings about a large fraction of asymmetric stem cell divisions. In the absence of stem cell growth factors, the barrier to differentiation is broken and overall growth is faster, even if the stem cell number is conserved.ConclusionsOur interpretation of the experimental results validates the centrality of the concept of stem cell niche when tumor growth is fueled by cancer stem cells. Niche memory is found to be responsible for the characteristic population dynamics observed in tumorspheres. The model also shows why substratum stiffness has a deep influence on the behavior of cancer stem cells, stiffer substrates leading to a larger proportion of asymmetric doublings. A specific condition for the growth of the cancer stem cell number is also obtained

Dysregulation of mitophagy and mitochondrial homeostasis in cancer stem cells: Novel mechanism for anti-cancer stem cell-targeted cancer therapy.

Despite the potential of cancer medicine, cancer stem cells (CSCs) associated with chemoresistance and disease recurrence are the significant challenges currently opposing the efficacy of available cancer treatment options. Mitochondrial dynamics involving the fission-fusion cycle and mitophagy are the major contributing factors to better adaptation, enabling CSCs to survive and grow better under tumour micro-environment-associated stress. Moreover, mitophagy is balanced with mitochondrial biogenesis to maintain mitochondrial homeostasis in CSCs, which are necessary for the growth and maintenance of CSCs and regulate metabolic switching from glycolysis to oxidative phosphorylation. In this review, we discuss different aspects of mitochondrial dynamics, mitophagy, and mitochondrial homeostasis and their effects on modulating CSCs behaviour during cancer development. Moreover, the efficacy of pharmacological targeting of these cellular processes using anti-CSC drugs in combination with currently available chemotherapeutic drugs improves the patient's survival of aggressive cancer types.

Effect of hematopoietic progenitor cells on the biological characteristics of colon cancer tumor stem cells.

BackgroundCancer stem cells (CSCs) are a type of tumor cell that are self-sustaining and can differentiate into several different types of cells. The present study aims to investigate the effect of hematopoietic progenitor cells (HPCs) on the biological behavior of colon CSCs (CCSCs) and to determine the underlying molecular mechanisms of liver metastasis in colorectal cancer.MethodsSubsets of CCSCs were isolated from stem-like HCT116 cells and cocultured with CD133+ HPCs in vitro. Colony formation assay, and CCK-8 were used to assess the effects of HPCs on CCSC subsets. Invasive and migration assay were done to study the effects of HPCs mediated metastatic capacity of CCSC subsets. Expression of MMP-9, VEGF, E-cadherin and β-catenin was analyzed by qPCR and Western blotting.ResultsCCK-8 and colony formation assays showed that HPCs significantly promoted proliferation and colony formation of the CCSC subsets (P=0.031). HPCs also significantly enhanced the migration (P=0.011) and invasive capacity (P=0.001) of the CCSC subsets. Quantitative PCR showed that MMP-9 and VEGF expression in CCSC subsets were significantly upregulated (P=0.000 and P=0.005). Western blotting showed that MMP-9, VEGF and β-catenin expression in CCSC subsets were significantly upregulated (P=0.000, P=0.005, P=0.000). The protein expression levels of E-cadherin in the CCSC subsets was significantly downregulated (P=0.002).ConclusionsCD133+ HPCs enhanced migration, invasion and proliferation of CCSC subsets in vitro.

Effects of biomechanical forces on the biological behavior of cancer stem cells

Cancer stem cells (CSCs), dynamic subsets of cancer cells, are responsible for malignant progression. The unique properties of CSCs, including self-renewal, differentiation, and malignancy, closely depend on the tumor microenvironment. Mechanical components in the microenvironment, including matrix stiffness, fluid shear stress, compression and tension stress, affect the fate of CSCs and further influence the cancer process. This paper reviews recent studies of mechanical components and CSCs, and further discusses the intrinsic correlation among them. Regulatory mechanisms of mechanical microenvironment, which act on CSCs, have great potential for clinical application and provide different perspectives to drugs and treatment design.

Cancer Stem Cell Microenvironment Models with Biomaterial Scaffolds In Vitro

Defined by its potential for self-renewal, differentiation and tumorigenicity, cancer stem cells (CSCs) are considered responsible for drug resistance and relapse. To understand the behavior of CSC, the effects of the microenvironment in each tissue are a matter of great concerns for scientists in cancer biology. However, there are many complicated obstacles in the mimicking the microenvironment of CSCs even with current advanced technology. In this context, novel biomaterials have widely been assessed as in vitro platforms for their ability to mimic cancer microenvironment. These efforts should be successful to identify and characterize various CSCs specific in each type of cancer. Therefore, extracellular matrix scaffolds made of biomaterial will modulate the interactions and facilitate the investigation of CSC associated with biological phenomena simplifying the complexity of the microenvironment. In this review, we summarize latest advances in biomaterial scaffolds, which are exploited to mimic CSC microenvironment, and their chemical and biological requirements with discussion. The discussion includes the possible effects on both cells in tumors and microenvironment to propose what the critical factors are in controlling the CSC microenvironment focusing the future investigation. Our insights on their availability in drug screening will also follow the discussion.

Prediction of Cancer Stem Cell Fate by Surface-Enhanced Raman Scattering Functionalized Nanoprobes.

Cancer stem cells (CSCs) are the fundamental building blocks of cancer dissemination, so it is desirable to develop a technique to predict the behavior of CSCs during tumor initiation and relapse. It will provide a powerful tool for pathological prognosis. Currently, there exists no method of such prediction. Here, we introduce nickel-based functionalized nanoprobe facilitated surface enhanced Raman scattering (SERS) for prediction of cancer dissemination by undertaking CSC-based surveillance. SERS profiling of CSCs of various cell lines (breast cancer, cervical cancer, and lung cancer) was compared with their cancer counterparts for the prediction of prognosis, with statistical significance of single-cell sensitivity. The single-cell sensitivity is critical as even a few CSCs are capable of initiating a tumor. Intermediate states of CSC transmutation to cancer cells and its reverse were monitored, and nanoprobe-assisted SERS profiling was undertaken. We experimentally demonstrated that the quasi-intermediate CSC states have dissimilar profiles during the transformation from cancer to CSC and vice versa enabling statistical differentiation without ambiguity. It was also observed that molecular signatures of these opposite pathways are cancer-type specific. This observation provided additional clarity to the current understanding of relatively unfamiliar quasi-intermediate states; making it possible to predict CSC dissemination for variety of cancers with ∼99% accuracy. Nano probe-based prediction of CSC fate is a powerful prediction tool for ultrasensitive prognosis of malignancy in a complex environment. Such CSC-based cancer prognosis has never been proposed before. This prediction technique has potential to provide insights for cancer diagnosis and prognosis as well as for obtaining information instrumental in designing of meaningful CSC-based cancer therapeutics.

Biophysical and epigenetic regulation of cancer stemness, invasiveness and immune action.

The tumor microenvironment (TME) is an amalgam of multiple dysregulated biophysical cues that can alter cellular behavior through mechanotransductive signaling and epigenetic modifications. Through this review, we seek to characterize the extent of biophysical and epigenetic regulation of cancer stemness and tumor-associated immune cells in order to identify ideal targets for cancer therapy. Recent studies have identified cancer stemness and immune action as significant contributors to neoplastic disease, due to their susceptibility to microenvironmental influences. Matrix stiffening, altered vasculature, and resultant hypoxia within the TME can influence cancer stem cell (CSC) and immune cell behavior, as well as alter the epigenetic landscapes involved in cancer development. This review highlights the importance of aberrant biophysical cues in driving cancer progression through altered behavior of CSCs and immune cells, which in turn sustains further biophysical dysregulation. We examine current and potential therapeutic approaches that break this self-sustaining cycle of disease progression by targeting the presented biophysical and epigenetic signatures of cancer. We also summarize strategies including the normalization of the TME, targeted drug delivery, and inhibition of cancer-enabling epigenetic players.

Oncogenic miR-20b-5p contributes to malignant behaviors of breast cancer stem cells by bidirectionally regulating CCND1 and E2F1

BackgroundBreast cancer is the leading cause of cancer mortality in women worldwide. Therefore, it is of great significance to identify the biological mechanism of tumorigenesis and explore the development of breast cancer to achieve a better prognosis for individuals suffering from breast cancer. MicroRNAs (miRNAs) have become a hot topic in cancer research, but the underlying mechanism of its involvement in cancer remains unclear.MethodsThe miRNA profile between breast cancer stem cells (BCSCs, CD44+CD24−/low) and control MCF-7 breast cancer cells was obtained in a previous study. Based on biological analysis, miR-20b-5p was hypothesized to be a key factor due to the malignant behavior of BCSCs. Then, agomir-20b-5p and antagomir-20b-5p were transfected into MCF-7 and T47D breast cancer cells to detect cell migration, wound healing and proliferation, and lentivirus vectors silencing or overexpressing miR-20b-5p were transfected into T47D-CSCs to detect proliferation and apoptosis. The effect of miR-20b-5p on xenograft growth was investigated in vivo by transfection of a lentivirus-overexpression vector into T47D cells. The target genes were predicted by the online programs picTar, miRanda and TargetScan and verified by dual luciferase assay, and changes in protein expression were detected by western blot.ResultsMiR-20b-5p had the highest degree in both the miRNA-gene network and miRNA-GO network to regulate BCSCs. Overexpression of miR-20b-5p significantly promoted the migration and wound healing ability of MCF-7 cells and T47D cells compared with the control (P < 0.05). In addition, miR-20b-5p facilitated the proliferation of MCF-7 cells and T47D-CSCs (P < 0.05) and inhibited the apoptosis of T47D-CSCs (P < 0.05). Moreover, miR-20b-5p promoted xenograft growth compared with the control group (P < 0.05). Accordingly, potential targets of both CCND1 and E2F1 were predicted by bioinformatics analysis. MiR-20b-5p directly targeted both CCND1 and E2F1 in a dual luciferase assay, while antagomir-20b-5p downregulated the protein levels of CCND1 and E2F1.ConclusionsOncogenic miR-20b-5p was confirmed to promote the malignant behaviors of breast cancer cells and BCSCs. The underlying mechanism lies in that miR-20b-5p overall enhanced both CCND1 and E2F1 targets via bidirectional regulation probably involving direct downregulation and indirect upregulation.

Abstract 372: Macrophage contact-dependent stemness induction and progressive CSC enrichment during metastatic dissemination in breast cancer

Abstract Background: Cancer stem cells (CSCs) play an important role during metastatic progression of breast cancer. However, little is known, at the single cell level, about the process of stemness induction in non-stem cells or the dynamic behavior of CSCs during hematogenous dissemination. Methods: Here, we employed high-resolution intravital multiphoton microscopy with a SOX2/OCT4 responsive fluorescent biosensor for stemness to directly observe the induction of stemness in single non-stem cells and their evolution through the metastatic cascade in living animals using orthotopic breast cancer xenograft model. We confirmed our findings in vitro using tumor cell-macrophage co-culture assays. Results: We report that, both in vitro and in vivo, direct physical contact with macrophages induces stemness in non-stem cancer cells via juxtacrine Notch-Jagged1 signaling. In vivo, macrophage depletion with clodronate treatment showed a significant decrease in stem cells. In vitro, using either the fate mapping of non-stem cells with or without macrophage contact, or the origin-mapping of stem cells to find whether they originated from non-stem cells or pre-existing stem cells, we found that there was four-fold increase in new CSC induction after direct macrophage contact. In contrast, we did not see any role of macrophages in the expansion of pre-existing CSCs, both in vivo and in vitro, indicating that macrophage contact-dependent stem induction is the primary mechanism of CSC generation. Using immunohistochemical staining in fixed tissue and live imaging of primary tumors and lungs in mice using optical windows, we found that during the course of dissemination of tumor cells from the primary site, CSCs become progressively enriched in the tumor cell population as they approach dissemination doorways (known as TMEM, Tumor MicroEnvironment of Metastasis), intravasate, circulate and arrive at the lung. Association with and passage through TMEM doorways is the step that generates the greatest enrichment in CSCs (~ 60-fold). On arrival in the lung, CSCs represent more than 75% of the disseminated tumor cell population, greatly enriched compared with their representation in the bulk primary tumor of ~ 1%. Conclusion: Overall, these data indicate, for the first time, that macrophages associated with TMEM induce CSCs and promote TMEM-mediated CSC intravasation and early metastatic seeding. Our results are consistent with the dramatic enrichment of cancer stem cell markers in association with TMEM in breast cancer patients (Kim et al 2020 AACR abstract) and support a strategy for anti-metastatic therapy. Citation Format: Ved P. Sharma, Yarong Wang, Binwu Tang, George S. Karagiannis, Emily A. Xue, David Entenberg, Lucia Borriello, Anouchka Coste, Joan G. Jones, Chinmay R. Surve, Dominic Esposito, Maja H. Oktay, Lalage M. Wakefield, John S. Condeelis. Macrophage contact-dependent stemness induction and progressive CSC enrichment during metastatic dissemination in breast cancer [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 372.

Rat Bone Marrow-Derived Mesenchymal Stem Cells Promote the Migration and Invasion of Colorectal Cancer Stem Cells.

BackgroundColorectal cancer is one of the most common cancers and the second leading cause of cancer-related deaths worldwide. Targeting cancer stem cells (CSCs) may be a novel strategy for the treatment of colorectal cancer. Previous studies have shown that bone marrow-derived MSCs (BM-MSCs) promote tumor growth and metastasis. However, the role of rat BM-MSCs in the biological behaviors of colorectal CSCs remains unclear until now.Materials and MethodsBM-MSCs were isolated from rats and characterized. CSCs were enriched from HCT116 cells using the microsphere culture method, and the microspheres incubated for at least 10 passages were termed HCT116-CSCs that were characterized. The effects of rat BM-MSCs on migration and invasion of HCT116-CSCs were examined using transwell migration and invasion assays and xenograft tumor growth assay.ResultsRat BM-MSCs appeared typical stem cell morphology. Flow cytometry revealed positive CD29 and CD44 expression in rat BM-MSCs at passage 3, and rat BM-MSCs were found to differentiate into osteocytes following incubation in osteogenic induction medium. Microscopy, flow cytometric detection of stem cell surface markers, colony-formation assay and transwell migration and invasion assays characterized the successful preparation of HCT116-CSCs, and subcutaneous injection of HCT116-CSCs produced xenograft tumors in nude mice, while HE staining of the xenograft tumors displayed cancer specimen shapes. Transwell migration and invasion assays showed that rat BM-MSCs promoted the migration and invasion of HCT116-CSCs, and injection of rat BM-MSCs was found to promote the growth of the mouse xenograft tumor derived from HCT116-CSCs.ConclusionRat BM-MSCs promote the migration and invasion of colorectal CSCs, and colorectal CSCs may be a potential target for the therapy against colorectal cancer.

Targeting protein palmitoylation decreases palmitate‑induced sphere formation of human liver cancer cells.

Although non-alcoholic fatty liver disease (NAFLD) is considered a benign disorder, hepatic steatosis has been proposed to be involved in the tumorigenesis of liver cancer. However, the underlying mechanism for carcinogenesis in fatty liver diseases remains unclear. Cancer stem cells (CSCs) have been hypothesized to serve a key role in tumorigenesis. Tumor formation begins with a subset of heterogeneous cells that share properties with stem cells, such as self-renewal and undifferentiated properties. Our previous study reported that the saturated fatty acid palmitate (PA) significantly enhanced the CSC properties of the HepG2 human liver cancer cell line; however, its underlying mechanisms are unknown. In the present study, a proteomic approach was used to investigate the palmitoylation of proteins in HepG2 CSCs. CSC behavior was induced in HepG2 cells via 200 µM PA. Proteomic analysis was performed to identify post-transcriptional modifications of proteins in HepG2 CSCs in response to PA treatment. The present study identified proteins modified by palmitoylation in HepG2 CSC spheres formed following PA treatment. It was therefore hypothesized that palmitoylation may be crucial for CSC sphere formation. Furthermore, the present study demonstrated that two palmitoylation inhibitors, tunicamycin (5, 10 and 25 µg/ml) and 2-bromohexadecanoic acid (25, 50 and 150 µM), significantly decreased CSC sphere formation without affecting cell viability. An association was identified between sphere formation capacity and tumor-initiating capacity of CSCs. The results of the present study demonstrated that protein palmitoylation may influence the PA-induced CSC tumor-initiating capacity, and that the inhibition of palmitoylation may be a suitable chemopreventive strategy for treating patients with NAFLD.