Isolation and characterization of breast cancer stem cell-like phenotype by Oct4 promoter-mediated activity

SIRT4 Promotes Pancreatic Cancer Stemness by Enhancing Histone Lactylation and Epigenetic Reprogramming Stimulated by Calcium Signaling

Mitochondria Sirtuins including SIRT4 erase a variety of posttranslational modifications from mitochondria proteins, leading to metabolic reprogramming that acts as a tumor suppressor, oncogenic promotor, or both. However, the factors and the underlying mechanisms that stimulate and relay such a signaling cascade are poorly understood. Here, we reveal that the voltage-gated calcium channel subunit α2δ1-mediated calcium signaling can upregulate the expression of SIRT4, which is highly expressed in α2δ1-positive pancreatic tumor-initiating cells (TICs). Furthermore, SIRT4 is functionally sufficient and indispensable to promote TIC properties of pancreatic cancer cells by directly deacetylating ENO1 at K358, leading to attenuated ENO1's RNA-binding capacity, enhanced glycolytic substrate 2-PG affinity, and subsequently robust catalytic activity with boosted glycolytic ability and increased production of lactate acid. Interestingly, both SIRT4 and deacetylated mimetic of ENO1-K358 can increase the lactylation of histones at multiple sites including H3K9 and H3K18 sites, which resulted in epigenetic reprogramming to directly activate a variety of pathways that are essential for stemness. Hence, the study links α2δ1-mediated calcium signaling to SIRT4-mediated histone lactylation epigenetic reprogramming in promoting the stem cell-like properties of pancreatic cancer, which holds significant potential for the development of novel therapeutic strategies by targeting TICs of pancreatic cancer.

ALDH1A1 as a marker for metastasis initiating cells: A mechanistic insight

Since metastasis accounts for the majority of cancer morbidity and mortality, attempts are focused to block metastasis and metastasis initiating cellular programs. It is generally believed that hypoxia, reactive oxygen species (ROS) and the dysregulated redox pathways regulate metastasis. Although induction of epithelial to mesenchymal transition (EMT) can initiate cell motility to different sites other than the primary site, the initiation of a secondary tumor at a distant site depends on self-renewal property of cancer stem cell (CSC) property. That subset of metastatic cells possessing CSC property are referred to as metastasis initiating cells (MICs). Among the different cellular intermediates regulating metastasis in response to hypoxia by inducing EMT and self-renewal property, ALDH1A1 is a critical molecule, which can be used as a marker for MICs in a wide variety of malignancies. The cytosolic ALDHs can irreversibly convert retinal to retinoic acid (RA), which initiates RA signaling, important for self-renewal and EMT. The metastasis permissive tumor microenvironment increases the expression of ALDH1A1, primarily through HIF1α, and leads to metabolic reprograming through OXPHOS regulation. The ALDH1A1 expression and its high activity can reprogram the cancer cells with the transcriptional upregulation of several genes, involved in EMT through RA signaling to manifest hybrid EMT or Hybrid E/M phenotype, which is important for acquiring the characteristics of MICs. Thus, the review on this topic highlights the use of ALDH1A1 as a marker for MICs, and reporters for the marker can be effectively used to trace the population in mouse models, and to screen drugs that target MICs.

Cancer stem cells: advances in knowledge and implications for cancer therapy

Cancer stem cells (CSCs), a small subset of cells in tumors that are characterized by self-renewal and continuous proliferation, lead to tumorigenesis, metastasis, and maintain tumor heterogeneity. Cancer continues to be a significant global disease burden. In the past, surgery, radiotherapy, and chemotherapy were the main cancer treatments. The technology of cancer treatments continues to develop and advance, and the emergence of targeted therapy, and immunotherapy provides more options for patients to a certain extent. However, the limitations of efficacy and treatment resistance are still inevitable. Our review begins with a brief introduction of the historical discoveries, original hypotheses, and pathways that regulate CSCs, such as WNT/β-Catenin, hedgehog, Notch, NF-κB, JAK/STAT, TGF-β, PI3K/AKT, PPAR pathway, and their crosstalk. We focus on the role of CSCs in various therapeutic outcomes and resistance, including how the treatments affect the content of CSCs and the alteration of related molecules, CSCs-mediated therapeutic resistance, and the clinical value of targeting CSCs in patients with refractory, progressed or advanced tumors. In summary, CSCs affect therapeutic efficacy, and the treatment method of targeting CSCs is still difficult to determine. Clarifying regulatory mechanisms and targeting biomarkers of CSCs is currently the mainstream idea.

Nobiletin Inhibits Breast Cancer Stem Cell by Regulating the Cell Cycle: A Comprehensive Bioinformatics Analysis and In Vitro Experiments

Inhibiting breast cancer stem cell (BCSC) signaling pathways is a strategic method for successfully treating breast cancer. Nobiletin (NOB) is a compound widely found in orange peel that exhibits a toxic effect on various types of cancer cells, and inhibits the signaling pathways that regulate the properties of BCSCs; however, the effects of NOB on BCSCs remain elusive. The purpose of this study was to determine the target genes of NOB for inhibiting BCSCs using in vitro three-dimensional breast cancer cell culture (mammospheres) and in silico approaches. We combined in vitro experiments to develop mammospheres and conducted cytotoxicity, next-generation sequencing, and bioinformatics analyses, such as gene ontology, the Reactome pathway enrichment, network topology, gene set enrichment analysis, hub genes selection, genetic alterations, prognostic value related to the mRNA expression, and mRNA and protein expression of potential NOB target genes that inhibit BCSCs. Here, we show that NOB inhibited BCSCs in mammospheres from MCF-7 cells. We also identified CDC6, CHEK1, BRCA1, UCHL5, TOP2A, MTMR4, and EXO1 as potential NOB targets inhibiting BCSCs. NOB decreased G0/G1, but increased the G2/M cell population. These findings showed that NOB is a potential therapeutic candidate for BCSCs treatment by regulating cell cycle.

HDAC9/p300/F-actin immunoexpression and migration analysis for malignant melanoma stem cell

Melanoma is an aggressive tumor with a poor prognosis that worsens in the metastatic phase. Distruptions of epigenetic mechanisms is known to effect cancer stem cells (CSCs) activity. Malignant melanoma (MM) progression may be promoted by changes in the genetic structure of CSC. Thus, treatments that target epigenetic modifications could be a promising weapon, especially in melanoma. Here, we compared p300, HDAC9, and F-actin proteins in melanoma CSCs (CD133+), non-CSCs (CD133-) and CHL-1 cell line, as well as cell migration and division rates. At 4 and 6 h, P300 protein levels in CHL-1 and CD133 + were remarkably similar, and the CD133- showed increases in expression levels as the incubation period lengthened. HDAC9 protein intensity decreased in CHL-1, increased in the CD133-, and remained relatively unchanged in the CD133+ as the incubation period lengthened. The mean value of F-actin expression level increased in all cell group with time, when the highest increase observed in CHL-1. In conclusion, our studies contribute to the management of metastatic diseases in the future and offer new insight into the molecular basis of the initiation and progression of MM.

Establishment and characterization of a novel cancer stem-like cell of cholangiocarcinoma

Cholangiocarcinoma (CCA) is an aggressive malignant tumor of bile duct epithelia. Recent evidence suggests the impact of cancer stem cells (CSC) on the therapeutic resistance of CCA; however, the knowledge of CSC in CCA is limited due to the lack of a CSC model. In this study, we successfully established a stable sphere-forming CCA stem-like cell, KKU-055-CSC, from the original CCA cell line, KKU-055. The KKU-055-CSC exhibits CSC characteristics, including: (1) the ability to grow stably and withstand continuous passage for a long period of culture in the stem cell medium, (2) high expression of stem cell markers, (3) low responsiveness to standard chemotherapy drugs, (4) multilineage differentiation, and (5) faster and constant expansive tumor formation in xenograft mouse models. To identify the CCA-CSC-associated pathway, we have undertaken a global proteomics and functional cluster/network analysis. Proteomics identified the 5925 proteins in total, and the significantly upregulated proteins in CSC compared with FCS-induced differentiated CSC and its parental cells were extracted. Network analysis revealed that high mobility group A1 (HMGA1) and Aurora A signaling through the signal transducer and activator of transcription 3 pathways were enriched in KKU-055-CSC. Knockdown of HMGA1 in KKU-055-CSC suppressed the expression of stem cell markers, induced the differentiation followed by cell proliferation, and enhanced sensitivity to chemotherapy drugs including Aurora A inhibitors. In silico analysis indicated that the expression of HMGA1 was correlated with Aurora A expressions and poor survival of CCA patients. In conclusion, we have established a unique CCA stem-like cell model and identified the HMGA1-Aurora A signaling as an important pathway for CSC-CCA.

Breast Cancer Stem Cells: Signaling Pathways, Cellular Interactions, and Therapeutic Implications

Breast cancer stem cells (BCSCs) constitute a small population of cells within breast cancer and are characterized by their ability to self-renew, differentiate, and recapitulate the heterogeneity of the tumor. Clinically, BCSCs have been correlated with cancer progression, metastasis, relapse, and drug resistance. The tumorigenic roles of BCSCs have been extensively reviewed and will not be the major focus of the current review. Here, we aim to highlight how the crucial intrinsic signaling pathways regulate the fate of BCSCs, including the Wnt, Notch, Hedgehog, and NF-κB signaling pathways, as well as how different cell populations crosstalk with BCSCs within the TME, including adipocytes, endothelial cells, fibroblasts, and immune cells. Based on the molecular and cellular activities of BCSCs, we will also summarize the targeting strategies for BCSCs and related clinical trials. This review will highlight that BCSC development in breast cancer is impacted by both BCSC endogenous signaling and external factors in the TME, which provides an insight into how to establish a comprehensively therapeutic strategy to target BCSCs for breast cancer treatments.

siRNA-mediated silencing of Nanog reduces stemness properties and increases the sensitivity of HepG2 cells to cisplatin

Liver cancer is one of the most lethal cancers having worldwide prevalence. Despite significant progress in cancer therapy, liver cancer-induced mortality is very high. Nanog, as an essential transcription factor modulating cellular multipotency, causes tumor progression, drug resistance, and preserves stemness properties in various tumors such as liver cancer. Thus, this research was conducted to evaluate the impact of combination therapy of Nanog siRNA/cisplatin on the sensitivity of liver cancer cells to this drug. HepG2 cells were transfected with Nanog siRNA and treated with cisplatin, individually and in combination. Then, it was observed that in transfected HepG2 cells, Nanog expression was significantly reduced at mRNA level and also these cells were sensitized to cisplatin. In addition, to assess the impact of Nanog siRNA and cisplatin individually and in combination on cells' viability, migration capacity, apoptosis, and cell cycle progression, the MTT, wound healing, colony formation assay, Annexin V/PI staining, and flow cytometry assays were applied on HepG2 cells, respectively. Also, the quantitive Real-Time PCR was used to check the expression of stemness-associated genes (CD44, CD133, and Sox2), and apoptosis-related genes (caspase-3, 8, 9, BAX and Bcl2) after combination therapy. It is indicated that the combination of Nanog siRNA and cisplatin significantly reduced proliferation, migration, and colony formation ability, as well as increased apoptosis rate, and cell cycle arrest. Also, it is found that the combination of Nanog siRNA and cisplatin down-regulated the expression of stemness-associated genes and up-regulated apoptosis-related genes in HepG2 cells. Hence, it can be suggested that Nanog inhibition in combination with cisplatin is a potential therapeutic strategy for developing new therapeutic approaches for liver cancer.

The Enrichment of Breast Cancer Stem Cells from MCF7 Breast Cancer Cell Line Using Spheroid Culture Technique

Breast cancer is the most common malignancy worldwide in females, representing 29% of all cancer new cases and 14% of cancer deaths in the world. Amongst the reasons for the high mortality rate is resistance to chemotherapy resulting in therapeutic failure. Various studies have shown that the presence of cancer stem cells (CSCs) in breast tumors is responsible for chemotherapy resistance and tumor recurrence. This CSC population possesses the characteristics of normal stem cells, including their ability to self-renewal and give rise to other epithelial cells. One thing that unique to the CSC population is their ability to escape from chemotherapy drugs; this can make them resistant to therapy and able to repopulate the cancer. Isolation and enrichment of breast CSCs (BCSCs) is required in order to study their characteristics and the behavior that enables them to drive breast tumor development, in order to develop better therapies. This chapter describes a method for the isolation and enrichment of BCSCs from the MCF7 breast cancer cell line, which consists of a heterogeneous breast cancer cell population. This method depends on cancer stem cell behavior, specifically an ability to self-renew and form spheroids in harsh conditions that allow only cancer cells with stem cell characteristics to survive and form spheroids.

Microfluidic Tandem Mechanical Sorting System for Enhanced Cancer Stem Cell Isolation and Ingredient Screening

Robust isolation of cancer stem cells (CSCs) in a high-throughput, label-free manner is critical for understanding tumor heterogeneity and developing therapeutic strategies targeting CSCs. Cell-mechanics-based microfluidic sorting systems provide efficient and specific platforms for investigation of stem cell-like characteristics on the basis of cell deformability and cell-substrate adhesion properties. In the present study, a microfluidic tandem mechanical sorting system is developed to enrich CSCs with high flexibility and low adhesive capacity. In the integrated microfluidic system, cancer cells are driven by hydrodynamic forces to flow continuously through two featured devices, which are functionalized with sequentially variable microbarriers and surface-coated fluid mixing microchannels, respectively. Collected deformable and low-adhesive cancer cells exhibit enhanced stem cell-like properties with higher stemness and metastasis capacity both in vitro and in vivo, compared with each single device separation. Using these devices, bioactive natural compound screening targeting CSCs is performed and a potent therapeutic compound isoliquiritigenin from licorice is identified to inhibit the lung cancer stem cell phenotype. Taken together, this microfluidic tandem mechanical sorting system can facilitate drug screening targeting CSCs and the analysis of signals regulating CSC function in drug resistance.

Lineage Plasticity in Cancer: The Tale of a Skin-Walker

Lineage plasticity, the switching of cells from one lineage to another, has been recognized as a cardinal property essential for embryonic development, tissue repair and homeostasis. However, such a highly regulated process goes awry when cancer cells exploit this inherent ability to their advantage, resulting in tumorigenesis, relapse, metastasis and therapy resistance. In this review, we summarize our current understanding on the role of lineage plasticity in tumor progression and therapeutic resistance in multiple cancers. Lineage plasticity can be triggered by treatment itself and is reported across various solid as well as liquid tumors. Here, we focus on the importance of lineage switching in tumor progression and therapeutic resistance of solid tumors such as the prostate, lung, hepatocellular and colorectal carcinoma and the myeloid and lymphoid lineage switch observed in leukemias. Besides this, we also discuss the role of epithelial-mesenchymal transition (EMT) in facilitating the lineage switch in biphasic cancers such as aggressive carcinosarcomas. We also discuss the mechanisms involved, current therapeutic approaches and challenges that lie ahead in taming the scourge of lineage plasticity in cancer.

Reporters of Cancer Stem Cells as a Tool for Drug Discovery

In view of the importance of cancer stem cells (CSCs) in chemoresistance, metastasis and recurrence, the biology of CSCs were explored in detail. Based on that, several modalities were proposed to target them. In spite of the several clinical trials, a successful CSC-targeting drug is yet to be identified. The number of molecules screened and entered for clinical trial for CSC-targeting is comparatively low, compared to other drugs. The bottle neck is the lack of a high-throughput adaptable screening strategy for CSCs. This review is aimed to identify suitable reporters for CSCs that can be used to identify the heterogeneous CSC populations, including quiescent CSCs, proliferative CSCs, drug resistant CSCs and metastatic CSCs. Analysis of the tumor microenvironment regulating CSCs revealed that the factors in CSC-niche activates effector molecules that function as CSC markers, including pluripotency markers, CD133, ABCG2 and ALDH1A1. Among these factors OCT4, SOX2, NANOG, ABCG2 and ALDH1A1 are ideal for making reporters for CSCs. The pluripotency molecules, like OCT4, SOX2 and NANOG, regulate self-renewal, chemoresistance and metastasis. ABCG2 is a known regulator of drug resistance while ALDH1A1 modulates self-renewal, chemoresistance and metastasis. Considering the heterogeneity of CSCs, including a quiescent population and a proliferative population with metastatic ability, we propose the use of a combination of reporters. A dual reporter consisting of a pluripotency marker and a marker like ALDH1A1 will be useful in screening drugs that target CSCs.

Exploitation of the vitamin A/retinoic acid axis depletes ALDH1-positive cancer stem cells and re-sensitises resistant non-small cell lung cancer cells to cisplatin

Despite advances in personalised medicine and the emerging role of immune checkpoints in directing treatment decisions in subsets of lung cancer patients, non-small cell lung cancer (NSCLC) remains the most common cause of cancer-related deaths worldwide. The development of drug resistance plays a key role in the relapse of lung cancer patients in the clinical setting, mainly due to the unlimited renewal capacity of residual cancer stem cells (CSCs) within the tumour cell population during chemotherapy. In this study, we investigated the function of the CSC marker, aldehyde dehydrogenase (ALDH1) in retinoic acid cell signalling using an in vitro model of cisplatin resistant NSCLC. The addition of key components in retinoic acid cell signalling, all-trans retinoic acid (ATRA) and retinol to cisplatin chemotherapy, significantly reduced ALDH1-positive cell subsets in cisplatin resistant NSCLC cells relative to their sensitive counterparts resulting in the re-sensitisation of chemo-resistant cells to the cytotoxic effects of cisplatin. Furthermore, combination of ATRA or retinol with cisplatin significantly inhibited cell proliferation, colony formation and increased cisplatin-induced apoptosis. This increase in apoptosis may, at least in part, be due to differential gene expression of the retinoic acid (RARα/β) and retinoid X (RXRα) nuclear receptors in cisplatin-resistant lung cancer cells. These data support the concept of exploiting the retinoic acid signalling cascade as a novel strategy in targeting subsets of CSCs in cisplatin resistant lung tumours.

LncRNAs and microRNAs as Essential Regulators of Stemness in Breast Cancer Stem Cells

Breast cancer is an aggressive disease with a high incidence in women worldwide. Two decades ago, a controversial hypothesis was proposed that cancer arises from a subpopulation of "tumor initiating cells" or "cancer stem cells-like" (CSC). Today, CSC are defined as small subset of somatic cancer cells within a tumor with self-renewal properties driven by the aberrant expression of genes involved in the maintenance of a stemness-like phenotype. The understanding of the underlying cellular and molecular mechanisms involved in the maintenance of CSC subpopulation are fundamental in the development and persistence of breast cancer. Nowadays, the hypothesis suggests that genetic and epigenetic alterations give rise to breast cancer stem cells (bCSC), which are responsible for self-renewal, tumor growth, chemoresistance, poor prognosis and low survival in patients. However, the prominence of bCSC, as well as the molecular mechanisms that regulates and promotes the malignant phenotypes, are still poorly understood. The role of non-coding RNAs (ncRNAs), such as long non-coding RNAs (lncRNAs) and microRNAs (miRNAs) acting as oncogenes or tumor suppressor genes has been recently highlighted by a plethora of studies in breast cancer. These ncRNAs positively or negatively impact on different signaling pathways that govern the cancer hallmarks associated with bCSC, making them attractive targets for therapy. In this review, we present a current summary of the studies on the pivotal roles of lncRNAs and microRNAs in the regulation of genes associated to stemness of bCSC.

Targeting cancer stem cells for reversing therapy resistance: mechanism, signaling, and prospective agents

Cancer stem cells (CSCs) show a self-renewal capacity and differentiation potential that contribute to tumor progression and therapy resistance. However, the underlying processes are still unclear. Elucidation of the key hallmarks and resistance mechanisms of CSCs may help improve patient outcomes and reduce relapse by altering therapeutic regimens. Here, we reviewed the identification of CSCs, the intrinsic and extrinsic mechanisms of therapy resistance in CSCs, the signaling pathways of CSCs that mediate treatment failure, and potential CSC-targeting agents in various tumors from the clinical perspective. Targeting the mechanisms and pathways described here might contribute to further drug discovery and therapy.

Advances in Liver Cancer Stem Cell Isolation and their Characterization

Over the last decade research on cancer stem cells (CSC) significantly contributed to a better understanding of tumor biology. Given their similarity to normal stem cells, i.e. self-renewal and pluripotency the need arises to develop robust protocols for the isolation and characterization of CSCs. As with other malignancies, hepatic tumors are composed of a heterogeneous population of cells including liver cancer stem cells (LCSC). Yet, a precise understanding of why stem cells become cancerous is still lacking. There is unmet need to develop robust protocols for the successful isolation of LCSCs from human tissue resection material as to assist in the development of molecular targeted therapies. Here we review the research progress made in the isolation and characterization of LCSCs by considering a wide range of cell surface markers and sorting methods, as applied to side populations, microsphere cultures and the gradient centrifugation method. We emphasize the different fluorescence activated cell sorting methods and the possibility to enrich LCSCs by immunomagnetic beads. We review the specificity of functional assays by considering ABCG transporter and ALDH1 enzyme activities and evaluate the in vivo tumorigenicity of LCSCs in highly sensitive bioassays. Finally, we evaluate different LCSC markers in association with viral and non-viral liver disease and explore the potential of novel drug delivery systems targeting CD133, EpCAM, CD13 and CD90 for the development of molecular targeted therapies. Graphical Abstract.

Trailblazing perspectives on targeting breast cancer stem cells

Breast cancer (BCa) is one of the most prevalent malignant tumors affecting women's health worldwide. The recurrence and metastasis of BCa have made it a long-standing challenge to achieve remission-persistent or disease-undetectable clinical outcomes. Cancer stem cells (CSCs) possess the ability to self-renew and generate heterogeneous tumor bulk. The existence of CSCs has been found to be vital in the initiation, metastasis, therapy resistance, and recurrence of tumors across cancer types. Because CSCs grow slowly in their dormant state, they are insensitive to conventional chemotherapies; however, when CSCs emerge from their dormant state and become clinically evident, they usually acquire genetic traits that make them resistant to existing therapies. Moreover, CSCs also show evidence of acquired drug resistance in synchrony with tumor relapses. The concept of CSCs provides a new treatment strategy for BCa. In this review, we highlight the recent advances in research on breast CSCs and their association with epithelial-mesenchymal transition (EMT), circulating tumor cells (CTCs), plasticity of tumor cells, tumor microenvironment (TME), T-cell modulatory protein PD-L1, and non-coding RNAs. On the basis that CSCs are associated with multiple dysregulated biological processes, we envisage that increased understanding of disease sub-classification, selected combination of conventional treatment, molecular aberration directed therapy, immunotherapy, and CSC targeting/sensitizing strategy might improve the treatment outcome of patients with advanced BCa. We also discuss novel perspectives on new drugs and therapeutics purposing the potent and selective expunging of CSCs.

Pluripotent Stem Cells: Cancer Study, Therapy, and Vaccination

INTRODUCTION

Pluripotent stem cells (PSCs) are promising tools for modern regenerative medicine applications because of their stemness properties, which include unlimited self-renewal and the ability to differentiate into all cell types in the body. Evidence suggests that a rare population of cells within a tumor, termed cancer stem cells (CSCs), exhibit stemness and phenotypic plasticity properties that are primarily responsible for resistance to chemotherapy, radiotherapy, metastasis, cancer development, and tumor relapse. Different therapeutic approaches that target CSCs have been developed for tumor eradication.

RESULTS AND DISCUSSION

In this review, we first provide an overview of different viewpoints about the origin of CSCs. Particular attention has been paid to views believe that CSCs are probably appeared through dysregulation of very small embryonic-like stem cells (VSELs) which reside in various tissues as the main candidate for tissue-specific stem cells. The expression of pluripotency markers in these two types of cells can strengthen the validity of this theory. In this regard, we discuss the common properties of CSCs and PSCs, and highlight the potential of PSCs in cancer studies, therapeutic applications, as well as educating the immune system against CSCs.

CONCLUSION

In conclusion, the resemblance of CSCs to PSCs can provide an appropriate source of CSC-specific antigens through cultivation of PSCs which brings to light promising ideas for prophylactic and therapeutic cancer vaccine development.

Immunization against leukemia inhibitory factor and its receptor suppresses tumor formation of breast cancer initiating cells in BALB/c mouse

Immunotherapy is a promising approach for specific targeting of cancer cells. Leukemia inhibitory factor (LIF) regulates several features of cancers and cancer stem cells (CSCs) through binding to LIF receptor (LIFR). In this study, we investigated the consensus of LIF and LIFR immunization on the growth of mouse mammary tumors. For this purpose, mouse LIF and LIFR were designed as truncated proteins, expressed in E. coli and then injected to mice as individual and mixed antigens. The results showed the production of neutralizing antibodies and secretion of interferon-γ and interleukin-2 in response to immunization. In continue, the immunized mice were subjected for tumor formation challenge by inoculation of the breast CSCs derived from MC4-L2 cells. Development of the breast tumors was observed in all the control mice, while the tumors appeared in 75% of animals in the LIF group. LIFR injection, individually or in combination with LIF, strongly inhibited the tumor growth to only 25% of the mice. Moreover, a delay in tumor appearance was observed in the immunized mice compared to the controls. Immunostaining of the tumor sections confirmed the expression of LIF and LIFR. In conclusion, LIF and LIFR might be effective targets for immunotherapy of the tumors that express these proteins.

The Relevance of Transcription Factors in Gastric and Colorectal Cancer Stem Cells Identification and Eradication

Gastric and colorectal cancers have a high incidence and mortality worldwide. The presence of cancer stem cells (CSCs) within the tumor mass has been indicated as the main reason for tumor relapse, metastasis and therapy resistance, leading to poor overall survival. Thus, the elimination of CSCs became a crucial goal for cancer treatment. The identification of these cells has been performed by using cell-surface markers, a reliable approach, however it lacks specificity and usually differs among tumor type and in some cases even within the same type. In theory, the ideal CSC markers are those that are required to maintain their stemness features. The knowledge that CSCs exhibit characteristics comparable to normal stem cells that could be associated with the expression of similar transcription factors (TFs) including SOX2, OCT4, NANOG, KLF4 and c-Myc, and signaling pathways such as the Wnt/β-catenin, Hedgehog (Hh), Notch and PI3K/AKT/mTOR directed the attention to the use of these similarities to identify and target CSCs in different tumor types. Several studies have demonstrated that the abnormal expression of some TFs and the dysregulation of signaling pathways are associated with tumorigenesis and CSC phenotype. The disclosure of common and appropriate biomarkers for CSCs will provide an incredible tool for cancer prognosis and treatment. Therefore, this review aims to gather the new insights in gastric and colorectal CSC identification specially by using TFs as biomarkers and divulge promising drugs that have been found and tested for targeting these cells.