MSC-regulated microRNAs converge on the transcription factor FOXP2 and promote breast cancer metastasis

Role of Mesenchymal Stem/Stromal Cells in Head and Neck Cancer-Regulatory Mechanisms of Tumorigenic and Immune Activity, Chemotherapy Resistance, and Therapeutic Benefits of Stromal Cell-Based Pharmacological Strategies

Head and neck cancer (HNC) entails a heterogenous neoplastic disease that arises from the mucosal epithelium of the upper respiratory system and the gastrointestinal tract. It is characterized by high morbidity and mortality, being the eighth most common cancer worldwide. It is believed that the mesenchymal/stem stromal cells (MSCs) present in the tumour milieu play a key role in the modulation of tumour initiation, development and patient outcomes; they also influence the resistance to cisplatin-based chemotherapy, the gold standard for advanced HNC. MSCs are multipotent, heterogeneous and mobile cells. Although no MSC-specific markers exist, they can be recognized based on several others, such as CD73, CD90 and CD105, while lacking the presence of CD45, CD34, CD14 or CD11b, CD79α, or CD19 and HLA-DR antigens; they share phenotypic similarity with stromal cells and their capacity to differentiate into other cell types. In the tumour niche, MSC populations are characterized by cell quiescence, self-renewal capacity, low reactive oxygen species production and the acquisition of epithelial-to-mesenchymal transition properties. They may play a key role in the process of acquiring drug resistance and thus in treatment failure. The present narrative review examines the links between MSCs and HNC, as well as the different mechanisms involved in the development of resistance to current chemo-radiotherapies in HNC. It also examines the possibilities of pharmacological targeting of stemness-related chemoresistance in HNSCC. It describes promising new strategies to optimize chemoradiotherapy, with the potential to personalize patient treatment approaches, and highlights future therapeutic perspectives in HNC.

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.

Mesenchymal Stem Cell-Secreted Exosomes and Soluble Signals Regulate Breast Cancer Metastatic Dormancy: Current Progress and Future Outlook

Breast cancer is most common in women, and in most cases there is no evidence of spread and the primary tumor is removed, resulting in a 'cure'. However, in 10% to 30% of these women, distant metastases recur after years to decades. This is due to breast cancer cells disseminating to distant organs and lying quiescent. This is called metastatic dormancy. Dormant cells are generally resistant to chemotherapy, hormone therapy and immunotherapy as they are non-cycling and receive survival signals from their microenvironment. In this state, they are clinically irrelevant. However, risk factors, including aging and inflammation can awaken dormant cells and cause breast cancer recurrences, which may happen even more than ten years after the primary tumor removal. How these breast cancer cells remain in dormancy is being unraveled. A key element appears to be the mesenchymal stem cells in the bone marrow that have been shown to promote breast cancer metastatic dormancy in recent studies. Indirect co-culture, direct co-culture and exosome extraction were conducted to investigate the modes of signal operation. Multiple signaling molecules act in this process including both protein factors and microRNAs. We integrate these studies to summarize current findings and gaps in the field and suggest future research directions for this field.

Genetic analysis of PALB2 gene WD40 domain in canine mammary tumour patients

BACKGROUND

DNA repair mechanisms are essential for tumorigenesis and disruption of HR mechanism is an important predisposing factor of human breast cancers (BC). PALB2 is an important part of the HR. There are similarities between canine mammary tumours (CMT) and BCs. As its human counterpart, PALB2 mutations could be a predisposing factor of CMT.

OBJECTIVES

In this study, we aimed to investigate the impacts of PALB2 variants on tumorigenesis and canine mammary tumor (CMT) malignancy.

METHODS

We performed Sanger sequencing to detect germline mutations in the WD40 domain of the canine PALB2 gene in CMT patients. We conducted in silico analysis to investigate the variants, and compared the germline PALB2 mutations in humans that cause breast cancer (BC) with the variants detected in dogs with CMT.

RESULTS

We identified an intronic (c.3096+8C>G) variant, two exonic (p.A1050V and p.R1354R) variants, and a 3' UTR variant (c.4071T>C). Of these, p.R1354R and c.4071T>C novel variants were identified for the first time in this study. We found that the p.A1050V mutation had a significant effect. However, we could not determine sufficient similarity due to the differences in nucleotide/amino acid sequences between two species. Nonetheless, possible variants of human sequences in the exact location as their dog counterparts are associated with several cancer types, implying that the variants could be crucial for tumorigenesis in dogs. Our results did not show any effect of the variants on tumor malignancy.

CONCLUSIONS

The current project is the first study investigating the relationship between the PALB2 gene WD40 domain and CMTs. Our findings will contribute to a better understanding of the pathogenic mechanism of the PALB2 gene in CMTs. In humans, variant positions in canines have been linked to cancer-related phenotypes such as familial BC, endometrial tumor, and hereditary cancer predisposition syndrome. The results of bioinformatics analyses should be investigated through functional tests or case-control studies.

Promoter of lncRNA MORT is aberrantly methylated in colorectal cancer

Aberrant DNA methylation plays essential roles in the colorectal cancer (CRC) carcinogenesis and has been demonstrated as a promising marker for cancer early detection. In this project, methylation status of the MORT promoter was studied in CRC and their marginal tissues using qMSP assay. Furthermore, we investigated the molecular function of MORT in CRC progression using computational analysis. The results showed a high methylation level of MORT promoter in CRC tissues. By in silico analysis, we found that MORT downregulation could promote the proliferation of CRC cells via sponging of has-miR-574-5p and has-miR-31-5p, and alteration of their targets expression pattern such as MYOCD and FOXP2. In conclusion, based on our results, promoter hypermethylation of MORT might be considered as a potential biomarker for CRC detection.

Staufen1 Represses the FOXA1-Regulated Transcriptome by Destabilizing FOXA1 mRNA in Colorectal Cancer Cells

Transcription factors play key roles in development and disease by controlling gene expression. Forkhead box A1 (FOXA1), is a pioneer transcription factor essential for mouse development and functions as an oncogene in prostate and breast cancer. In colorectal cancer (CRC), FOXA1 is significantly downregulated and high FOXA1 expression is associated with better prognosis, suggesting potential tumor suppressive functions. We therefore investigated the regulation of FOXA1 expression in CRC, focusing on well-differentiated CRC cells, where FOXA1 is robustly expressed. Genome-wide RNA stability assays identified FOXA1 as an unstable mRNA in CRC cells. We validated FOXA1 mRNA instability in multiple CRC cell lines and in patient-derived CRC organoids, and found that the FOXA1 3'UTR confers instability to the FOXA1 transcript. RNA pulldowns and mass spectrometry identified Staufen1 (STAU1) as a potential regulator of FOXA1 mRNA. Indeed, STAU1 knockdown resulted in increased FOXA1 mRNA and protein expression due to increased FOXA1 mRNA stability. Consistent with these data, RNA-seq following STAU1 knockdown in CRC cells revealed that FOXA1 targets were upregulated upon STAU1 knockdown. Collectively, this study uncovers a molecular mechanism by which FOXA1 is regulated in CRC cells and provides insights into our understanding of the complex mechanisms of gene regulation in cancer.

miRNAs in the prognosis of triple-negative breast cancer: A review

Triple-Negative Breast Cancer (TNBC) is a highly aggressive and invasive type of breast cancer (BC) with high mortality rate wherein effective target medicaments are lacking. It is a very heterogeneous group with several subtypes that account for 10-20% of cancer among women globally, being negative for three most important receptors (estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2)), with an early and high recurrence resulting in poor survival rate. Therefore, a more thorough knowledge on carcinogenesis of TNBC is required for the development of personalized treatment options. miRNAs can either promote or suppress tumorigenesis and have been linked to a number of features of cancer progression, including proliferation, metastasis, apoptosis, and epithelial-mesenchymal transition (EMT). Recent miRNA research shows that there is great potential for the development of novel biomarkers as they have emerged as drivers of tumorigenesis and provide opportunities to target various components involved in TNBC, thus helping to solve this difficult-to-treat disease. In this review, we summarize the most relevant miRNAs that play an essential role in TNBC biology. Their role with regard to molecular mechanisms underlying TNBC progression has been discussed, and their potential use as therapeutic or prognostic markers to unravel the intricacy of TNBC based on the pieces of evidence obtained from various works of literature has been briefly addressed.

Cancer-associated mesenchymal stem/stromal cells: role in progression and potential targets for therapeutic approaches

Malignancies contain a relatively small number of Mesenchymal stem/stromal cells (MSCs), constituting a crucial tumor microenvironment (TME) component. These cells comprise approximately 0.01-5% of the total TME cell population. MSC differentiation potential and their interaction with the tumor environment enable these cells to affect tumor cells' growth, immune evasion, metastasis, drug resistance, and angiogenesis. This type of MSC, known as cancer-associated mesenchymal stem/stromal cells (CA-MSCs (interacts with tumor/non-tumor cells in the TME and affects their function by producing cytokines, chemokines, and various growth factors to facilitate tumor cell migration, survival, proliferation, and tumor progression. Considering that the effect of different cells on each other in the TME is a multi-faceted relationship, it is essential to discover the role of these relationships for targeting in tumor therapy. Due to the immunomodulatory role and the tissue repair characteristic of MSCs, these cells can help tumor growth from different aspects. CA-MSCs indirectly suppress antitumor immune response through several mechanisms, including decreasing dendritic cells (DCs) antigen presentation potential, disrupting natural killer (NK) cell differentiation, inducing immunoinhibitory subsets like tumor-associated macrophages (TAMs) and Treg cells, and immune checkpoint expression to reduce effector T cell antitumor responses. Therefore, if these cells can be targeted for treatment so that their population decreases, we can hope for the treatment and improvement of the tumor conditions. Also, various studies show that CA-MSCs in the TME can affect other vital aspects of a tumor, including cell proliferation, drug resistance, angiogenesis, and tumor cell invasion and metastasis. In this review article, we will discuss in detail some of the mechanisms by which CA-MSCs suppress the innate and adaptive immune systems and other mechanisms related to tumor progression.

The Multifunction Role of Tumor-Associated Mesenchymal Stem Cells and Their Interaction with Immune Cells in Breast Cancer

Mesenchymal stem cells (MSCs) are a heterogeneous group of progenitor cells that play a multifunctional role including tissue regeneration, self-renewal properties, and differentiate into cells of mesodermal lineage such as adipocytes, osteoblasts, and chondrocytes. MSCs come into contact with tumor microenvironment (TME) and differentiate into tumor-associated MSCs (TA-MSCs). Various substances such as chemokines, cytokines, growth factors, and others are released by tumor cells to recruit MSCs. TA-MSCs induced epithelial-mesenchymal transition (EMT) program which mediates tumor growth progression, migration, and invasion. Role of MSCs in the tumor progression, stemness, malignancy, and treatment resistance in the breast cancer TME. Immunomodulation by MSCs is mediated by a combination of cell contact-dependent mechanisms and soluble substances. Monocytes/macrophages, dendritic cells, T cells, B cells, and NK cells all show signs of MSCs' immunomodulatory capability. In a complicated interplay initiated by MSCs, anti-inflammatory monocytes/macrophages and regulatory T cells (Tregs) play a key role, as they unveil their full immunomodulatory potential. MSC- secreted cytokines are commonly blamed for the interaction between MSCs, monocytes, and Tregs. Here, we review the current knowledge of cellular and molecular mechanisms involved in MSC-mediated immunomodulation and focus on the role MSCs play in breast cancer progression and its TME.Abbreviation MSC: Mesenchymal Stem Cells; TME: Tumor Microenvironment; TAMS; Tumour-associated Macrophages; ECM: Extracellular matrix; CAFs: Cancer-associated Fibroblasts; CFUs: Colony-forming unit Fibroblasts; Tregs: T regulatory cells; Bregs; Regulatory B cells; IFN-γ: Interferon-gamma; TNF-α: Tumour Necrosis Factor-alpha; IL: Interleukin; TGF-β: transforming growth factorβ; PGE2: Prostaglandin E2; CXCR: Chemokine Receptor; Blimp-1; B lymphocyte-induced maturation protein-1; CCL: Chemokine motif ligand; EMT: Epithelial-mesenchymal transition.

Tumor microenvironment-induced tumor cell plasticity: relationship with hypoxic stress and impact on tumor resistance

The role of tumor interaction with stromal components during carcinogenesis is crucial for the design of efficient cancer treatment approaches. It is widely admitted that tumor hypoxic stress is associated with tumor aggressiveness and thus impacts susceptibility and resistance to different types of treatments. Notable biological processes that hypoxia functions in include its regulation of tumor heterogeneity and plasticity. While hypoxia has been reported as a major player in tumor survival and dissemination regulation, the significance of hypoxia inducible factors in cancer stem cell development remains poorly understood. Several reports indicate that the emergence of cancer stem cells in addition to their phenotype and function within a hypoxic tumor microenvironment impacts cancer progression. In this respect, evidence showed that cancer stem cells are key elements of intratumoral heterogeneity and more importantly are responsible for tumor relapse and escape to treatments. This paper briefly reviews our current knowledge of the interaction between tumor hypoxic stress and its role in stemness acquisition and maintenance. Our review extensively covers the influence of hypoxia on the formation and maintenance of cancer stem cells and discusses the potential of targeting hypoxia-induced alterations in the expression and function of the so far known stem cell markers in cancer therapy approaches. We believe that a better and integrated understanding of the effect of hypoxia on stemness during carcinogenesis might lead to new strategies for exploiting hypoxia-associated pathways and their targeting in the clinical setting in order to overcome resistance mechanisms. More importantly, at the present time, efforts are oriented towards the design of innovative therapeutical approaches that specifically target cancer stem cells.

FOXP2 confers oncogenic effects in prostate cancer

Identification oncogenes is fundamental to revealing the molecular basis of cancer. Here, we found that FOXP2 is overexpressed in human prostate cancer cells and prostate tumors, but its expression is absent in normal prostate epithelial cells and low in benign prostatic hyperplasia. FOXP2 is a FOX transcription factor family member and tightly associated with vocal development. To date, little is known regarding the link of FOXP2 to prostate cancer. We observed that high FOXP2 expression and frequent amplification are significantly associated with high Gleason score. Ectopic expression of FOXP2 induces malignant transformation of mouse NIH3T3 fibroblasts and human prostate epithelial cell RWPE-1. Conversely, FOXP2 knockdown suppresses the proliferation of prostate cancer cells. Transgenic overexpression of FOXP2 in the mouse prostate causes prostatic intraepithelial neoplasia. Overexpression of FOXP2 aberrantly activates oncogenic MET signaling and inhibition of MET signaling effectively reverts the FOXP2-induced oncogenic phenotype. CUT&Tag assay identified FOXP2-binding sites located in MET and its associated gene HGF. Additionally, the novel recurrent FOXP2-CPED1 fusion identified in prostate tumors results in high expression of truncated FOXP2, which exhibit a similar capacity for malignant transformation. Together, our data indicate that FOXP2 is involved in tumorigenicity of prostate.

Cancer Stem Cell Relationship with Pro-Tumoral Inflammatory Microenvironment

Inflammatory processes and cancer stem cells (CSCs) are increasingly recognized as factors in the development of tumors. Emerging evidence indicates that CSCs are associated with cancer properties such as metastasis, treatment resistance, and disease recurrence. However, the precise interaction between CSCs and the immune microenvironment remains unexplored. Although evasion of the immune system by CSCs has been extensively studied, new research demonstrates that CSCs can also control and even profit from the immune response. This review provides an overview of the reciprocal interplay between CSCs and tumor-infiltrating immune cells, collecting pertinent data about how CSCs stimulate leukocyte reprogramming, resulting in pro-tumor immune cells that promote metastasis, chemoresistance, tumorigenicity, and even a rise in the number of CSCs. Tumor-associated macrophages, neutrophils, Th17 and regulatory T cells, mesenchymal stem cells, and cancer-associated fibroblasts, as well as the signaling pathways involved in these pro-tumor activities, are among the immune cells studied. Although cytotoxic leukocytes have the potential to eliminate CSCs, immune evasion mechanisms in CSCs and their clinical implications are also known. We intended to compile experimental findings that provide direct evidence of interactions between CSCs and the immune system and CSCs and the inflammatory milieu. In addition, we aimed to summarize key concepts in order to comprehend the cross-talk between CSCs and the tumor microenvironment as a crucial process for the effective design of anti-CSC therapies.

The Role of Mesenchymal Stem Cells in Modulating the Breast Cancer Microenvironment

The role of mesenchymal stem cells (MSCs) in the breast tumor microenvironment (TME) is significant and multifaceted. MSCs are recruited to breast tumor sites through molecular signals released by tumor sites. Once in the TME, MSCs undergo polarization and interact with various cell populations, including immune cells, cancer-associated fibroblasts (CAFs), cancer stem cells (CSCs), and breast cancer cells. In most cases, MSCs play roles in breast cancer therapeutic resistance, but there is also evidence that indicates their abilities to sensitize cancer cells to chemotherapy and radiotherapy. MSCs possess inherent regenerative and homing properties, making them attractive candidates for cell-based therapies. Therefore, MSCs can be engineered to express therapeutic molecules or deliver anti-cancer agents directly to tumor sites. Unraveling the intricate relationship between MSCs and the breast TME has the potential to uncover novel therapeutic targets and advance our understanding of breast cancer biology.

miRNA-1260b Promotes Breast Cancer Cell Migration and Invasion by Downregulating CCDC134

BACKGROUND

Breast cancer (BRCA) is the most common type of cancer among women worldwide. MiR-1260b has been widely demonstrated to participate in multiple crucial biological functions of cancer tumorigenesis, but its functional effect and mechanism in human breast cancer have not been fully understood.

METHODS

qRT-PCR was used to detect miR-1260b expression in 29 pairs of breast cancer tissues and normal adjacent tissues. Besides, the expression level of miR-1260b in BRCA cells was also further validated by qRT-PCR. miR-1260b played its role in the prognostic process by using Kaplan-Meier curves. In addition, miR-1260b knockdown and target gene CCDC134 overexpression model was constructed in cell line MDA-MB-231. Transwell migration and invasion assay was performed to analyze the effect of miR-1260b and CCDC134 on the biological function of BRCA cells. TargetScan and miRNAWalk were used to find possible target mRNAs. The relationship between CCDC134 and immune cell surface markers was analyzed using TIMER and database and the XIANTAO platform. GSEA analysis was used to identify possible CCDC134-associated molecular mechanisms and pathways.

RESULTS

In the present study, miR-1260b expression was significantly upregulated in human breast cancer tissue and a panel of human breast cancer cell lines, while the secretory protein coiled-coil domain containing 134 (CCDC134) exhibited lower mRNA expression. High expression of miR-1260b was associated with poor overall survival among the patients by KM plot. Knockdown of miR-1260b significantly suppressed breast cancer cell migration and invasion and yielded the opposite result. In addition, overexpression of CCDC134 could inhibit breast cancer migration and invasion, and knockdown yielded the opposite result. There were significant positive correlations of CCDC134 with CD25 (IL2RA), CD80 and CD86. GSEA showed that miR-1260b could function through the MAPK pathway by downregulating CCDC134.

CONCLUSION

Collectively, these results suggested that miR-1260b might be an oncogene of breast cancer and might promote the migration and invasion of BRCA cells by down-regulating its target gene CCDC134 and activating MAPK signaling pathway as well as inhibiting immune function and causing immune escape in human breast cancer.

DNASE1L3 regulation by transcription factor FOXP2 affects the proliferation, migration, invasion and tube formation of lung adenocarcinoma

Lung adenocarcinoma (LUAD) is prone to bone metastasis, resulting in poor prognosis. The present study aimed to detect the expression of deoxyribonuclease 1-like 3 (DNASE1L3) and forkhead-box P2 (FOXP2) in LUAD cells to investigate the role of DNASE1L3 in the regulation of proliferation, migration, invasion and tube formation of LUAD cells and how FOXP2 affects DNASE1L3 expression. The expression of DNASE1L3 and FOXP2 in LUAD cells was analyzed by reverse transcription-quantitative PCR (RT-qPCR) and western blotting. The transfection efficiency of DNASE1L3 overexpression plasmids, FOXP2 overexpression or interference plasmids into A549 cells was also confirmed by RT-qPCR and western blotting. The viability, proliferation, migration and invasion and tube formation of LUAD cells following transfection was in turn detected by MTT, EdU staining, wound healing, Transwell and tube formation assay. The expression of proteins associated with epithelial-mesenchymal transformation and tube formation was detected by western blotting. Binding between DNASE1L3 and FOXP2 was confirmed by dual-luciferase reporter assay and chromatin immunoprecipitation. Gene Expression Profiling Interactive Analysis database predicted that underexpression of DNASE1L3 in LUAD was associated with poor prognosis. DNASE1L3 expression was decreased in LUAD cells and overexpression of DNASE1L3 inhibited the proliferation, migration, invasion and tube formation of LUAD cells. Transcription factor FOXP2 positively regulated DNASE1L3 transcription in LUAD cells. FOXP2 was also underexpressed in LUAD cells and downregulation of FOXP2 promoted proliferation, migration, invasion and tube formation of LUAD cells, which was reversed by overexpression of DNASE1L3. In conclusion, DNASE1L3 was positively regulated by transcription factor FOXP2 and overexpression inhibited proliferation, migration, invasion and tube formation of LUAD cells.

Mesenchymal/stromal stem cells: necessary factors in tumour progression

Mesenchymal/stromal stem cells (MSCs) are a crucial component of the tumour microenvironment (TME). They can be recruited from normal tissues into the TME and educated by tumour cells to transform into tumour-associated MSCs, which are oncogenic cells that promote tumour development and progression by impacting or transforming into various kinds of cells, such as immune cells and endothelial cells. Targeting MSCs in the TME is a novel strategy to prevent malignant processes. Exosomes, as communicators, carry various RNAs and proteins and thus link MSCs and the TME, which provides options for improving outcomes and developing targeted treatment.

Mesenchymal Stem/Stromal Cells in Cancer: from Initiation to Metastasis

Mesenchymal stem/stromal cells (MSCs) exist in many tissues and have pleiotropic potential to self-renew and differentiate into multiple cell types. Recent research in tumor biology has focused on their low immunogenicity and tumorhoming properties. MSCs promote cancer initiation, progression, and metastasis through several different mechanisms, including epithelial-mesenchymal transition (EMT), angiogenesis, and through their interaction with immune cells. In this review, we discuss the recent advances in our understanding of the pathogenic role of MSCs in regulating tumor initiation, progression, and metastasis, thus providing a strong rationale for targeting MSCs in cancer therapy.

Mesenchymal stem/stromal cells in breast cancer development and management

Mesenchymal stem/stromal cells (MSCs) encompass a heterogeneous population of fibroblastic progenitor cells that reside in multiple tissues around the body. They are endowed with capacities to differentiate into multiple connective tissue lineages, including chondrocytes, adipocytes, and osteoblasts, and are thought to function as trophic cells recruited to sites of injury and inflammation where they contribute to tissue regeneration. In keeping with these roles, MSCs also to home to sites of breast tumorigenesis, akin to their migration to wounds, and participate in tumor stroma formation. Mounting evidence over the past two decades has described the critical regulatory roles for tumor-associated MSCs in various aspects of breast tumor pathogenesis, be it tumor initiation, growth, angiogenesis, tumor microenvironment formation, immune evasion, cancer cell migration, invasion, survival, therapeutic resistance, dissemination, and metastatic colonization. In this review, we present a brief summary of the role of MSCs in breast tumor development and progression, highlight some of the molecular frameworks underlying their pro-malignant contributions, and present evidence of their promising utility in breast cancer therapy.

Fate decisions of breast cancer stem cells in cancer progression

Breast cancer has a marked recurrence and metastatic trait and is one of the most prevalent malignancies affecting women’s health worldwide. Tumor initiation and progression begin after the cell goes from a quiescent to an activated state and requires different mechanisms to act in concert to regulate t a specific set of spectral genes for expression. Cancer stem cells (CSCs) have been proven to initiate and drive tumorigenesis due to their capability of self-renew and differentiate. In addition, CSCs are believed to be capable of causing resistance to anti-tumor drugs, recurrence and metastasis. Therefore, exploring the origin, regulatory mechanisms and ultimate fate decision of CSCs in breast cancer outcomes has far-reaching clinical implications for the development of breast cancer stem cell (BCSC)-targeted therapeutic strategies. In this review, we will highlight the contribution of BCSCs to breast cancer and explore the internal and external factors that regulate the fate of BCSCs.

A comprehensive in silico analysis of the deleterious nonsynonymous SNPs of human FOXP2 protein

FOXP2 encodes the forkhead transcription factor that plays a significant role in language development. Single nucleotide polymorphisms in FOXP2 have been linked to speech- language disorder, autism, cancer and schizophrenia. So, scrutinizing the functional SNPs to better understand their association in disease is an uphill task. The purpose of the current study was to identify the missense SNPs which have detrimental structural and functional effects on the FOXP2 protein. Multiple computational tools were employed to investigate the deleterious role of non-synonymous SNPs. Five variants as Y531H, L558P, R536G and R553C were found to be associated with diseases and located at the forkhead domain of the FOXP2 protein. Molecular docking analysis of FOXP2 DNA binding domain with its most common target sequence 5’-CAAATT-3’ predicted that R553C and L558P mutant variants destabilize protein structure by changing protein-DNA interface interactions and disruption of hydrogen bonds that may reduce the specificity and affinity of the binding. Further experimental investigations may need to verify whether this kind of structural and functional variations dysregulate protein activities and induce formation of disease.

Cutting the umbilical cord: Cancer stem cell-targeted therapeutics

Cancer Stem Cells (CSCs) are a notoriously quiescent subpopulation of cells within heterogeneous tumors exhibiting self-renewal, differentiation and drug-resistant capabilities leading to tumor relapse. Heterogeneous cell populations in tumor microenvironment develop an elaborate network of signalling and factors supporting the CSC population within a niche. Identification of specific biomarkers for CSCs facilitates their isolation. CSCs demonstrate abilities that bypass immune surveillance, exhibit resistance to therapy, and induce cancer recurrence while promoting altered metabolism of the bulk tumor, thereby encouraging metastasis. The fight against cancer is prone to relapse without discussing the issue of CSCs, making it imperative for encapsulation of current studies. In this review, we provide extensive knowledge of recent therapeutics developed that target CSCs via multiple signalling cascades, altered metabolism and the tumor microenvironment. Thorough understanding of the functioning of CSCs, their interaction with different cells in the tumor microenvironment as well as current gaps in knowledge are addressed. We present possible strategies to disrupt the cellular and molecular interplay within the tumor microenvironment and make it less conducive for CSCs, which may aid in their eradication with subsequently better treatment outcomes. In conclusion, we discuss a brief yet functional idea of emerging concepts in CSC biology to develop efficient therapeutics acting on cancer recurrence and metastasis.

Carcinoma Associated Mesenchymal Stem/Stromal Cells - Architects of the Pro-tumorigenic tumor microenvironment

The interaction between tumor cells and non-malignant hosts cells within the tumor microenvironment (TME) is critical to the pathophysiology of cancer. These non-malignant host cells, consisting of a variety of stromal, immune and endothelial cells, engage in a complex bidirectional crosstalk with the malignant tumor cells. Mesenchymal stem/stromal cells (MSCs) are one of these host cells, and they play a critical role in directing the formation and function of the entire TME. These MSCs are epigenetically reprogrammed by cancer cells to assume a strongly pro-tumorigenic phenotype and are referred to as carcinoma-associated mesenchymal stem/stromal cells (CA-MSCs). Studies over the last decade demonstrate that CA-MSCs not only directly interact with cancer cells to promote tumor growth and metastasis, but also orchestrate the formation of the TME. CA-MSCs can differentiate into virtually all stromal sub-lineages present in the TME, including pro-tumorigenic cancer associated fibroblasts (CAF), myofibroblasts, and adipocytes. CA-MSCs and the CAFs they produce, secrete much of the extracellular matrix in the TME. Furthermore, CA-MSC secreted factors promote angiogenesis, and recruit immunosuppressive myeloid cells effectively driving tumor immune exclusion. Thus CA-MSCs impact nearly every aspect of the TME. Despite their influence on cancer biology, as CA-MSCs represent a heterogenous population without a single definitive marker, significant confusion remains regarding the origin and proper identification CA-MSCs. This review will focus on the impact of CA-MSCs on cancer progression and metastasis and the ongoing work on CA-MSC identification, nomenclature and mechanism of action.

FOXP2 regulates thyroid cancer cell proliferation and apoptosis via transcriptional activation of RPS6KA6

The transcription factor, forkhead box P2 (FOXP2) has tumor-suppressive effects in several types of cancer. However, the regulatory role and underlying mechanism of FOXP2 in thyroid cancer (THCA) is not completely understood. In the present study, the mRNA expression levels of FOXP2 and ribosomal protein S6 kinase A6 (RPS6KA6) were evaluated using the GEPIA database and THCA cell lines. The association between FOXP2 and RPS6KA6 was analyzed using the LinkedOmics, and GEPIA databases. Then, the binding sites of FOXP2 and the RPS6KA6 promotor was predicted using the JASPAR database, and verified using a dual-luciferase reporter assay and chromatin immunoprecipitation. In addition, functional assays investigating FOXP2 and RPS6KA6 were conducted in the TPC-1 cell line. The data showed that FOXP2 and RPS6KA6 mRNA expression levels were decreased in the THCA tissues, and cell lines. Overexpression of FOXP2 inhibited cell proliferation and promoted apoptosis in the THCA cell lines. Furthermore, RPS6KA6 mRNA expression levels were reduced in THCA and were correlated with FOXP2 expression level. Mechanistic studies revealed that FOXP2 binds directly to the promotor region of RPS6KA6 and modulated the expression level of RPS6KA6 transcriptionally. In addition, rescue experiments showed that knockdown of RPS6KA6 expression reversed the effects of FOXP2 overexpression on THCA cell proliferation and apoptosis, and the regulation of FOXP2/RPS6KA6 may be associated with the PI3K/AKT pathway. In summary, FOXP2 was associated with the proliferation and apoptosis of human THCA cells via the transcriptional activation of RPS6KA6. The FOXP2/RPS6KA6 axis could be a promising target for the treatment of THCA.

Clinical potential of long non-coding RNA LINC01133 as a promising biomarker and therapeutic target in cancers

Recently, long intergenic non-protein coding RNA 01133 (LINC01133) was identified as a novel transcript in cancers. It modulates various hallmarks of cancers and acts as oncogenic in some cancers while tumor-suppressive in others. Furthermore, the expression of LINC01133 correlates with tumor size, advanced tumor node metastasis stage and lymphatic node metastasis, Ki-67 levels and overall survival of patients. Herein, the authors provide an in-depth analysis describing how LINC01133 modulates the multiple cancer-associated signaling pathways and the pathogenesis of various malignancies and treatment regimens. Based on the role played by LINC01133, the authors propose LINC01133 as both a potential biomarker and a therapeutic target in cancer.

Effects of Cell Density and Microenvironment on Stem Cell Mitochondria Transfer among Human Adipose-Derived Stem Cells and HEK293 Tumorigenic Cells

Stem cells (SC) are largely known for their potential to restore damaged tissue through various known mechanisms. Among these mechanisms is their ability to transfer healthy mitochondria to injured cells to rescue them. This mitochondrial transfer plays a critical role in the healing process. To determine the optimal parameters for inducing mitochondrial transfer between cells, we assessed mitochondrial transfer as a function of seeding density and in two-dimensional (2D) and semi three-dimensional (2.5D) culture models. Since mitochondrial transfer can occur through direct contact or secretion, the 2.5D culture model utilizes collagen to provide cells with a more physiologically relevant extracellular matrix and offers a more realistic representation of cell attachment and movement. Results demonstrate the dependence of mitochondrial transfer on cell density and the distance between donor and recipient cell. Furthermore, the differences found between the transfer of mitochondria in 2D and 2.5D microenvironments suggest an optimal mode of mitochondria transport. Using these parameters, we explored the effects on mitochondrial transfer between SCs and tumorigenic cells. HEK293 (HEK) is an immortalized cell line derived from human embryonic kidney cells which grow rapidly and form tumors in culture. Consequently, HEKs have been deemed tumorigenic and are widely used in cancer research. We observed mitochondrial transfer from SCs to HEK cells at significantly higher transfer rates when compared to a SC–SC co-culture system. Interestingly, our results also revealed an increase in the migratory ability of HEK cells when cultured with SCs. As more researchers find co-localization of stem cells and tumors in the human body, these results could be used to better understand their biological relationship and lead to enhanced therapeutic applications.

HN1L promotes stem cell-like properties by regulating TGF-β signaling pathway through targeting FOXP2 in prostate cancer

Dysregulated hematological and neurological expressed 1-like (HN1L) has been implicated in carcinogenesis of difference cancers, including hepatocellular carcinoma and breast cancer. However, the role of HN1L in the progression of prostate cancer (PCA) remains unknown. Therefore, we aimed to investigate the role of HN1L in stemness and progression of PCA. The expression of HN1L in PCA tissues and cells was determined by quantitative reverse-transcription polymerase chain reaction (qRT-PCR), western blot analysis, and/or immunohistochemistry (IHC). CD133+ cells were sorted from PCA cells using magnetic fluorescence cell sorting technology and were considered as cancer stem cells (CSCs). Sphere formation assays, transwell assays, and animal experiments were conducted to assess cell stemness, migration, invasion, and in vivo tumorigenesis, respectively. The results showed that HN1L expression was higher in PCA tissues and cells as compared with normal tissues and cells, as well as in CD133+ cells as compared with CD133- cells. HN1L knockdown significantly decreased the expression levels of CSC markers including OCT4 (POU class 5 homeobox 1), CD44, and SRY-box transcription factor 2, inhibited cell migration, invasion, and tumorigenesis and decreased the number of tumor spheroids and CD133+ cell population. Furthermore, we found that HN1L could bind to forkhead box P2 (FOXP2) and positively regulated transforming growth factor-β (TGF-β) expression via upregulation of FOXP2. In addition, the overexpression of TGF-β in HN1L-knockdown PCA cells increased the number of tumor spheroids and CD133+ cell population, as well as enhanced cell migration and invasion. Collectively, this study demonstrates that HN1L promotes stem cell-like properties and cancer progression by targeting FOXP2 through TGF-β signaling pathway in PCA.

Roles of mesenchymal stromal cells in the head and neck cancer microenvironment

Head and neck cancer (HNC), a common malignancy worldwide, is associated with high morbidity and mortality rates. Squamous cell carcinoma is the most common HNC type, followed by salivary gland carcinomas, head and neck sarcomas, and lymphomas. The microenvironment of HNCs comprises various cells that regulate tumor development. Recent studies have reported that the tumor microenvironment, which modulates cancer progression, regulates cancer treatment response. However, the presence of different types of stromal cells in cancers is a major challenge to elucidate the role of individual cells in tumor progression. The role of mesenchymal stromal cells (MSCs), which are a component of the tumor microenvironment, in HNC is unclear. The major impediment for characterizing the role of MSCs in cancer progression is the lack of MSC-specific markers and their phenotypic similarity with stromal cells. This review aimed to summarize the latest findings on the role of MSCs in the progression of HNC to improve our understanding of HNC pathophysiology.

Methylation Modification, Alternative Splicing, and Noncoding RNA Play a Role in Cancer Metastasis through Epigenetic Regulation

Metastasis is the leading cause of cancer-related deaths. Understanding the pathogenesis of metastasis at the molecular levels is of great significance for cancer research. However, the molecular diagnosis or treatment of cancer metastasis is limited. Accumulating and growing evidence shows that epigenetic changes are present in all human cancers, and epigenetic regulation is an indispensable factor to promote tumor metastasis. With the deepening of research and the advancement of technology, the function and mechanism of epigenetic regulation, including DNA methylation, histone/RNA modification, and precursor messenger RNA alternative splicing and noncoding RNAs, has become more increasingly clear. At present, the application of epigenetic therapies in tumor treatment is becoming a feasible therapeutic route. In this review, we looked for the key molecules in epigenetic regulation and discuss their relative regulating mechanisms in cancer metastasis. Furthermore, we highlight promising therapeutic strategies, including monitoring serum DNA for diagnostic purposes and early phase clinical trial therapies that target DNA and histone methylation. This may also be beneficial in finding new targets for further prognosis and diagnosis of cancer metastasis.

LncRNA SNHG7 Regulates Mesenchymal Stem Cell Through the Notch1/Jagged1/Hes-1 Signaling Pathway and Influences Folfirinox Resistance in Pancreatic Cancer

Pancreatic cancer (PC) is one of the deadliest gastrointestinal cancers, accounting for the fourth highest number of cancer-related fatalities. Increasing data suggests that mesenchymal stem cells (MSCs) might influence the drug resistance of GC cells in the tumor microenvironment and play essential roles in drug resistance development. However, the precise underlying process remains a mystery. The purpose of this study was to look at the control of MSC-induced SNHG7 in pancreatic cancer. In vitro and in vivo sphere formation, colony formation, and flow cytometry investigations revealed the stemness and Folfirinox resistance in pancreatic cancer cells. To confirm the direct connections between SNHG7 and other related targets, RNA pulldown and immunoprecipitation tests were performed. MSC co-culture enhanced the stemness and Folfirinox resistance in pancreatic cancer cells according to the findings. MSC co-culture increased SNHG7 expression in pancreatic cancer cells, contributing to the stemness and Folfirinox resistance. We demonstrated that Notch1 interacted with SNHG7 and could reverse the facilitative effect of SNHG7 on the stemness and Folfirinox resistance in pancreatic cancer cells. Finally, our findings showed that MSCs increased SNHG7 expression in pancreatic cancer cells, promoting the stemness and Folfirinox resistance via the Notch1/Jagged1/Hes-1 signaling pathway. These findings could provide a novel approach and therapeutic target for pancreatic cancer patients.

H19 Overexpression Improved Efficacy of Mesenchymal Stem Cells in Ulcerative Colitis by Modulating the miR-141/ICAM-1 and miR-139/CXCR4 Axes

Overexpression of C-X-C motif chemokine receptor 4 (CXCR4) and intercellular cell adhesion molecule-1 (ICAM-1) may promote homing of mesenchymal stem cells (MSC). In this study, we treated ulcerative colitis animals with MSC preconditioned with or without H19 and compared the therapeutic effect of MSC and MSC-H19. We evaluated the regulatory relationship of H19 vs. miR-141/miR-139 and miR-141/miR-139 vs. ICAM-1/CXCR4. We established an ulcerative colitis mouse model to assess the effect of MSC and MSC-H19. H19 was found to bind to miR-141 and miR-139. The activity of H19 was strongly decreased in cells c-transfected with miR-141/miR-139 and WT H19. ICAM-1 was confirmed to be targeted by miR-141 and CXCR4 was targeted by miR-139. The H19 expression showed a negative regulatory relationship with the miR-141 and miR-139 expression but a positive regulatory relationship with the ICAM-1 and CXCR4 expression. In summary, the overexpression of H19 in MSC downregulated miR-139 and miR-141, thus increasing the activity of their targets ICAM-1 and CXCR4, respectively, to exhibit therapeutic effects in ulcerative colitis.

Stem Cells and Cancer Stem Cells: The Jekyll and Hyde Scenario and Their Implications in Stem Cell Therapy

"Jekyll and Hyde" refers to persons with an unpredictably dual personality, who are battling between good and evil within themselves In this regard, even cells consist of good and evil counterparts. Normal stem cells (NSCs) and cancer stem cells (CSCs) are two types of cells that share some similar characteristics but have distinct functions that play a major role in physiological and pathophysiological development. In reality, NSCs such as the adult and embryonic stem cells, are the good cells and the ultimate treatment used in cell therapy. CSCs are the corrupted cells that are a subpopulation of cancer cells within the cancer microenvironment that grow into a massive tumour or malignancy that needs to be treated. Hence, understanding the connection between NSCs and CSCs is important not just in cancer development but also in their therapeutic implication, which is the focus of this review.

Adipose-derived stem/stromal cell secretome modulates breast cancer cell proliferation and differentiation state towards aggressiveness

It is becoming increasingly evident that mesenchymal stem/stromal cells are recruited by cancer cells from nearby endogenous host stroma and promote events such as tumor proliferation, angiogenesis, invasion, and metastasis, as well as mediate therapeutic resistance. Consequently, understanding the regulatory mechanisms of ASCs that influence the tumor microenvironment may provide an avenue for further treatment. To understand the role of the ASC secretome in breast cancer cell proliferation, death, and phenotype alteration, adipose-derived stem cell-conditioned medium (mASC) was used to cultivate MCF-7 and MDA-MB-231 cells. These breast cancer cells in mASC showed a shorter doubling time, higher frequency of EdU positivity, and higher levels of phosphorylated histone 3. In addition, increased expression of cyclin B1 was observed, suggesting that proliferation was induced. The mASC was also able to increase apoptosis in MCF-7 cells, which was confirmed by caspase-7 activation. The number of tumor-initiating cells (CD44⁺ CD24^-/low) and migration capacity were increased in cells cultivated in mASC. These data collectively suggest that ASC-conditioned medium can induce selective pressure by increasing cell proliferation, giving rise to a more aggressive phenotype in MCF-7 and MDA-MB-231 cells. Our study provides a foundation for further elucidation of the precise mechanism underlying ASCs in breast cancer cells and the modulation of ASCs in potential therapeutic uses.

MicroRNAs as Important Regulators Mediate the Multiple Differentiation of Mesenchymal Stromal Cells

MicroRNAs (miRNAs) are endogenous short non-encoding RNAs which play a critical role on the output of the proteins, and influence multiple biological characteristics of the cells and physiological processes in the body. Mesenchymal stem/stromal cells (MSCs) are adult multipotent stem cells and characterized by self-renewal and multidifferentiation and have been widely used for disease treatment and regenerative medicine. Meanwhile, MSCs play a critical role in maintaining homeostasis in the body, and dysfunction of MSC differentiation leads to many diseases. The differentiation of MSCs is a complex physiological process and is the result of programmed expression of a series of genes. It has been extensively proven that the differentiation process or programmed gene expression is also regulated accurately by miRNAs. The differentiation of MSCs regulated by miRNAs is also a complex, interdependent, and dynamic process, and a full understanding of the role of miRNAs will provide clues on the appropriate upregulation or downregulation of corresponding miRNAs to mediate the differentiation efficiency. This review summarizes the roles and associated signaling pathways of miRNAs in adipogenesis, chondrogenesis, and osteogenesis of MSCs, which may provide new hints on MSCs or miRNAs as therapeutic strategies for regenerative medicine and biotherapy for related diseases.

The LINC01119-SOCS5 axis as a critical theranostic in triple-negative breast cancer

The development of triple-negative breast cancer (TNBC) is critically regulated by certain tumor-microenvironment-associated cells called mesenchymal stem/stromal cells (MSCs), which we and others have shown promote TNBC progression by activating pro-malignant signaling in neighboring cancer cells. Characterization of these cascades would better our understanding of TNBC biology and bring about therapeutics that eliminate the morbidity and mortality associated with advanced disease. Here, we focused on the emerging class of RNAs called long non-coding RNAs or lncRNAs and utilized a MSC-supported TNBC progression model to identify specific family members of functional relevance to TNBC pathogenesis. Indeed, although some have been described to play functional roles in TNBC, activities of lncRNAs as mediators of tumor-microenvironment-driven TNBC development remain to be fully explored. We report that MSCs stimulate robust expression of LINC01119 in TNBC cells, which in turn induces suppressor of cytokine signaling 5 (SOCS5), leading to accelerated cancer cell growth and tumorigenesis. We show that LINC01119 and SOCS5 exhibit tight correlation across multiple breast cancer gene sets and that they are highly enriched in TNBC patient cohorts. Importantly, we present evidence that the LINC01119-SOCS5 axis represents a powerful prognostic indicator of adverse outcomes in TNBC patients, and demonstrate that its repression severely impairs cancer cell growth. Altogether, our findings identify LINC01119 as a major driver of TNBC development and delineate critical non-coding RNA theranostics of potential translational utility in the management of advanced TNBC, a class of tumors in most need of effective and targeted therapy.

Current understanding of epigenetics mechanism as a novel target in reducing cancer stem cells resistance

At present, after extensive studies in the field of cancer, cancer stem cells (CSCs) have been proposed as a major factor in tumor initiation, progression, metastasis, and recurrence. CSCs are a subpopulation of bulk tumors, with stem cell-like properties and tumorigenic capabilities, having the abilities of self-renewal and differentiation, thereby being able to generate heterogeneous lineages of cancer cells and lead to resistance toward anti-tumor treatments. Highly resistant to conventional chemo- and radiotherapy, CSCs have heterogeneity and can migrate to different organs and metastasize. Recent studies have demonstrated that the population of CSCs and the progression of cancer are increased by the deregulation of different epigenetic pathways having effects on gene expression patterns and key pathways connected with cell proliferation and survival. Further, epigenetic modifications (DNA methylation, histone modifications, and RNA methylations) have been revealed to be key drivers in the formation and maintenance of CSCs. Hence, identifying CSCs and targeting epigenetic pathways therein can offer new insights into the treatment of cancer. In the present review, recent studies are addressed in terms of the characteristics of CSCs, the resistance thereof, and the factors influencing the development thereof, with an emphasis on different types of epigenetic changes in genes and main signaling pathways involved therein. Finally, targeted therapy for CSCs by epigenetic drugs is referred to, which is a new approach in overcoming resistance and recurrence of cancer.

The emerging role of miRNA in the perturbation of tumor immune microenvironment in chemoresistance: Therapeutic implications

Chemoresistance is a major hindrance in cancer chemotherapies, a leading cause of tumor recurrence and cancer-related deaths. Cancer cells develop numerous strategies to elude immune attacks and are regulated by immunological factors. Cancer cells can alter the expression of several immune modulators to upregulate the activities of immune checkpoint pathways. Targeting the immune checkpoint inhibitors is a part of the cancer immunotherapy altered during carcinogenesis. These immune modulators have the capability to reprogram the tumor microenvironment, thereby change the efficacy of chemotherapeutics. In general, the sensitivity of drugs is reduced in the immunosuppressive tumor microenvironment, resulting in chemoresistance and tumor relapse. The regulation of microRNAs (miRNAs) is well established in cancer initiation, progression, and therapy. Intriguingly, miRNA affects cancer immune surveillance and immune response by targeting immune checkpoint inhibitors in the tumor microenvironment. miRNAs alter the gene expression at the post-transcriptional level, which modulates both innate and adaptive immune systems. Alteration of tumor immune microenvironment influences drug sensitivity towards cancer cells. Besides, the expression profile of immune-modulatory miRNAs can be used as a potential biomarker to predict the response and clinical outcomes in cancer immunotherapy and chemotherapy. Recent evidences have revealed that cancer-derived immune-modulatory miRNAs might be promising targets to counteract cancer immune escape, thereby increasing drug efficacy. In this review, we have compiled the role of miRNAs in overcoming the chemoresistance by modulating tumor microenvironment and discussed their preclinical and clinical implications.

The Anticancer Effects of Flavonoids through miRNAs Modulations in Triple-Negative Breast Cancer

Triple- negative breast cancer (TNBC) incidence rate has regularly risen over the last decades and is expected to increase in the future. Finding novel treatment options with minimum or no toxicity is of great importance in treating or preventing TNBC. Flavonoids are new attractive molecules that might fulfill this promising therapeutic option. Flavonoids have shown many biological activities, including antioxidant, anti-inflammatory, and anticancer effects. In addition to their anticancer effects by arresting the cell cycle, inducing apoptosis, and suppressing cancer cell proliferation, flavonoids can modulate non-coding microRNAs (miRNAs) function. Several preclinical and epidemiological studies indicate the possible therapeutic potential of these compounds. Flavonoids display a unique ability to change miRNAs' levels via different mechanisms, either by suppressing oncogenic miRNAs or activating oncosuppressor miRNAs or affecting transcriptional, epigenetic miRNA processing in TNBC. Flavonoids are not only involved in the regulation of miRNA-mediated cancer initiation, growth, proliferation, differentiation, invasion, metastasis, and epithelial-to-mesenchymal transition (EMT), but also control miRNAs-mediated biological processes that significantly impact TNBC, such as cell cycle, immune system, mitochondrial dysregulation, modulating signaling pathways, inflammation, and angiogenesis. In this review, we highlighted the role of miRNAs in TNBC cancer progression and the effect of flavonoids on miRNA regulation, emphasizing their anticipated role in the prevention and treatment of TNBC.

Hepatic stellate cells promote intrahepatic cholangiocarcinoma progression via NR4A2/osteopontin/Wnt signaling axis

Intrahepatic cholangiocarcinoma (ICC) is a highly fatal malignancy characterized by a vast amount of intra-tumoral fibroblasts. These fibroblasts are potentially implicated in maintaining the high aggressiveness of ICC, whereas its pro-cancer mechanisms remain scarcely reported. Here, by establishing co-culture models of ICC cells and hepatic stellate cells (HSCs), we identified that HSCs triggered the expression of nuclear receptor family 4 subgroup A member 2 (NR4A2), a transcription factor previously reported as a molecular switch between inflammation and cancer, in ICC cells. Functionally, NR4A2 promotes tumor proliferation, metastatic potentiality and represents an independent prognostic indicator for overall survival in ICC patients. Mechanistically, NR4A2 upregulates osteopontin (OPN) expression through transcriptional activation and thereby augments the activity of Wnt/β-catenin signaling. Intriguingly, in the context of co-culture, vascular endothelial growth factor (VEGF), a previously proved NR4A2 stimulus, not only enhances NR4A2 expression, but also can be blunted by the interference of the NR4A2-OPN axis. Altogether, this study suggests the NR4A2/OPN/Wnt signaling axis to be a pivotal executor of HSC-instigated cancer-promoting roles in ICC, and the NR4A2/OPN/VEGF positive feedback loop may help to reinforce the effect.

Novel molecular regulators of breast cancer stem cell plasticity and heterogeneity

Tumors consist of heterogeneous cell populations, and tumor heterogeneity plays key roles in regulating tumorigenesis, metastasis, recurrence and resistance to anti-tumor therapies. More and more studies suggest that cancer stem cells (CSCs) promote tumorigenesis, metastasis, recurrence and drug resistance as well as are the major source for heterogeneity of cancer cells. CD24^-CD44⁺ and ALDH⁺ are the most common markers for breast cancer stem cells (BCSCs). Previous studies showed that different BCSC markers label different BCSC populations, indicating the heterogeneity of BCSCs. Therefore, defining the regulation mechanisms of heterogeneous BCSCs is essential for precisely targeting BCSCs and treating breast cancer. In this review, we summarized the novel regulators existed in BCSCs and their niches for BCSC heterogeneity which has been discovered in recent years, and discussed their regulation mechanisms and the latest corresponding cancer treatments, which will extend our understanding on BCSC heterogeneity and plasticity, and provide better prognosis prediction and more efficient novel therapeutic strategies for breast cancer.

FOXA2-Interacting FOXP2 Prevents Epithelial-Mesenchymal Transition of Breast Cancer Cells by Stimulating E-Cadherin and PHF2 Transcription

FOXP2, a member of forkhead box transcription factor family, was first identified as a language-related gene that played an important role in language learning and facial movement. In addition, FOXP2 was also suggested regulating the progression of cancer cells. In previous studies, we found that FOXA2 inhibited epithelial-mesenchymal transition (EMT) in breast cancer cells. In this study, by identifying FOXA2-interacting proteins from FOXA2-pull-down cell lysates with Mass Spectrometry Analysis, we found that FOXP2 interacted with FOXA2. After confirming the interaction between FOXP2 and FOXA2 through Co-IP and immunofluorescence assays, we showed a correlated expression of FOXP2 and FOXA2 existing in clinical breast cancer samples. The overexpression of FOXP2 attenuated the mesenchymal phenotype whereas the stable knockdown of FOXP2 promoted EMT in breast cancer cells. Even though FOXP2 was believed to act as a transcriptional repressor in most cases, we found that FOXP2 could activate the expression of tumor suppressor PHF2. Meanwhile, we also found that FOXP2 could endogenously bind to the promoter of E-cadherin and activate its transcription. This transcriptional activity of FOXP2 relied on its interaction with FOXA2. Furthermore, the stable knockdown of FOXP2 enhanced the metastatic capacity of breast cancer cells in vivo. Together, the results suggested that FOXP2 could inhibit EMT by activating the transcription of certain genes, such as E-cadherin and PHF2, in concert with FOXA2 in breast cancer cells.

Exosomal miR-30a and miR-222 derived from colon cancer mesenchymal stem cells promote the tumorigenicity of colon cancer through targeting MIA3

Background

Multipotent mesenchymal stem cells (MSCs) derived from virus tumors have been reported to contribute to malignant cell growth, invasion, and metastasis. However, the mechanism of communication between MSCs and colon cancer cells is poorly understood. Recent studies have suggested that exosomes are an important player in crosstalk between cells and could significantly suppress the invasion ability of human cancer cells (hCCs) when transfected with a microRNA inhibitor. However, to date, no study has illuminated the miRNA changes in exosomes derived from hCC-MSCs.

Methods

Colon cancer stem cells were cultured in medium and passaged to develop fibroblast-like morphology. Exosomes were collected using ExoQuick precipitation and exosome morphology was visualized by transmission electron microscopy. Small RNA sequencing was analyzed using an Illumina HiSeq4000 analyzer, and the expression of MIA3 was assessed by real-time PCR and Western blot. The functional roles of miR-30a and miR-222 in colon cancer cells were evaluated through cell and animal experiments.

Results

Our results showed that the characteristics of MSC-like cells (hCC-MSCs) derived from human colon cancer stem cells were comparable to those of bone marrow-derived MSCs, including surface antigens and the ability to multi-differentiate to osteocytes and adipocytes. Furthermore, we screened the microRNA (miRNA) profiles of exosomes derived from hCC-MSCs and the corresponding parent hCC-MSCs. We found a significant enrichment in the miR-30a and miR-222 level in hCC-MSC-derived exosomes. Furthermore, in vitro and in vivo experiments demonstrated that miR-30a and miR-222 bound to their shared downstream target, MIA3, to promote the ability of colon cells to proliferate, migrate, and metastasize, thus evidencing their functional roles as oncogenic miRNAs.

Conclusions

These data suggest that hCC-MSC-secreted exosomes promote colon cancer cell proliferation and metastasis through delivering miR-30a and miR-222. Subsequently, exosomal miR-30a and miR-222 simultaneously target MIA3, suppress its expression, and promote colon cell proliferation, migration, and metastasis.

iPSC-Derived Hereditary Breast Cancer Model Reveals the BRCA1-Deleted Tumor Niche as a New Culprit in Disease Progression

Tumor progression begins when cancer cells recruit tumor-associated stromal cells to produce a vascular niche, ultimately resulting in uncontrolled growth, invasion, and metastasis. It is poorly understood, though, how this process might be affected by deletions or mutations in the breast cancer type 1 susceptibility (BRCA1) gene in patients with a lifetime risk of developing breast and/or ovarian cancer. To model the BRCA1-deleted stroma, we first generated induced pluripotent stem cells (iPSCs) from patients carrying a germline deletion of exon 17 of the BRCA1 gene (BRCA1+/− who, based on their family histories, were at a high risk for cancer. Using peripheral blood mononuclear cells (PBMCs) of these two affected family members and two normal (BRCA1+/+) individuals, we established a number of iPSC clones via non-integrating Sendai virus-based delivery of the four OCT4, SOX2, KLF4, and c-MYC factors. Induced mesenchymal stem cells (iMSCs) were generated and used as normal and pathological stromal cells. In transcriptome analyses, BRCA1+/− iMSCs exhibited a unique pro-angiogenic signature: compared to non-mutated iMSCs, they expressed high levels of HIF-1α, angiogenic factors belonging to the VEGF, PDGF, and ANGPT subfamilies showing high angiogenic potential. This was confirmed in vitro through the increased capacity to generate tube-like structures compared to BRCA1+/+ iMSCs and in vivo by a matrigel plug angiogenesis assay where the BRCA1+/− iMSCs promoted the development of an extended and organized vessel network. We also reported a highly increased migration capacity of BRCA1+/− iMSCs through an in vitro wound healing assay that correlated with the upregulation of the periostin (POSTN). Finally, we assessed the ability of both iMSCs to facilitate the engraftment of murine breast cancer cells using a xenogenic 4T1 transplant model. The co-injection of BRCA1+/− iMSCs and 4T1 breast cancer cells into mouse mammary fat pads gave rise to highly aggressive tumor growth (2-fold increase in tumor volume compared to 4T1 alone, p = 0.01283) and a higher prevalence of spontaneous metastatic spread to the lungs. Here, we report for the first time a major effect of BRCA1 haploinsufficiency on tumor-associated stroma in the context of BRCA1-associated cancers. The unique iMSC model used here was generated using patient-specific iPSCs, which opens new therapeutic avenues for the prevention and personalized treatment of BRCA1-associated hereditary breast cancer.

The CXCL12 Crossroads in Cancer Stem Cells and Their Niche

Simple Summary

CXCL12 and its receptors have been extensively studied in cancer, including their influence on cancer stem cells (CSCs) and their niche. This intensive research has led to a better understanding of the crosstalk between CXCL12 and CSCs, which has aided in designing several drugs that are currently being tested in clinical trials. However, a comprehensive review has not been published to date. The aim of this review is to provide an overview on how CXCL12 axes are involved in the regulation and maintenance of CSCs, their presence and influence at different cellular levels within the CSC niche, and the current state-of-the-art of therapeutic approaches aimed to target the CXCL12 crossroads.

Abstract

Cancer stem cells (CSCs) are defined as a subpopulation of “stem”-like cells within the tumor with unique characteristics that allow them to maintain tumor growth, escape standard anti-tumor therapies and drive subsequent repopulation of the tumor. This is the result of their intrinsic “stem”-like features and the strong driving influence of the CSC niche, a subcompartment within the tumor microenvironment that includes a diverse group of cells focused on maintaining and supporting the CSC. CXCL12 is a chemokine that plays a crucial role in hematopoietic stem cell support and has been extensively reported to be involved in several cancer-related processes. In this review, we will provide the latest evidence about the interactions between CSC niche-derived CXCL12 and its receptors—CXCR4 and CXCR7—present on CSC populations across different tumor entities. The interactions facilitated by CXCL12/CXCR4/CXCR7 axes seem to be strongly linked to CSC “stem”-like features, tumor progression, and metastasis promotion. Altogether, this suggests a role for CXCL12 and its receptors in the maintenance of CSCs and the components of their niche. Moreover, we will also provide an update of the therapeutic options being currently tested to disrupt the CXCL12 axes in order to target, directly or indirectly, the CSC subpopulation.

Targeting FAPα-expressing tumor-associated mesenchymal stromal cells inhibits triple-negative breast cancer pulmonary metastasis

Tumor metastasis is the main cause of death in patients with triple-negative breast cancer (TNBC). Bone marrow-derived mesenchymal stem cells (BM-MSCs) have tropism towards tumor tissues, and can be converted into tumor-associated mesenchymal stromal cells (TA-MSCs) to facilitate TNBC metastasis through interactions with tumor-associated macrophages (TAMs). However, the underlying molecular mechanisms are complex and unclear, and effective strategies to suppress tumor metastasis via eliminating TA-MSCs are still lacking. Here, we demonstrate that fibroblast activation protein alpha (FAPα) was overexpressed in TA-MSCs, which prompts TA-MSCs to secrete multiple C-C motif chemokine ligands, promoting C-C motif chemokine receptor 2 (CCR2)⁺ TAM recruitment and facilitating TAM polarization into the M2 phenotype, thereby promoting TNBC pulmonary metastasis. Z-GP-DAVLBH, an FAPα-activated vinblastine prodrug, induces FAPα⁺ TA-MSC apoptosis, which significantly suppresses CCR2⁺ TAM recruitment and polarization, thus inhibiting pulmonary metastasis of orthotopic TNBC cell-derived xenografts and patient-derived xenografts. This study provides insight into an important role of FAPα in mediating TA-MSC-induced TNBC metastasis and provides compelling evidence that targeting TA-MSCs with an FAPα-activated prodrug is a promising strategy for suppressing TNBC metastasis.

Use of signals of positive and negative selection to distinguish cancer genes and passenger genes

A major goal of cancer genomics is to identify all genes that play critical roles in carcinogenesis. Most approaches focused on genes positively selected for mutations that drive carcinogenesis and neglected the role of negative selection. Some studies have actually concluded that negative selection has no role in cancer evolution. We have re-examined the role of negative selection in tumor evolution through the analysis of the patterns of somatic mutations affecting the coding sequences of human genes. Our analyses have confirmed that tumor suppressor genes are positively selected for inactivating mutations, oncogenes, however, were found to display signals of both negative selection for inactivating mutations and positive selection for activating mutations. Significantly, we have identified numerous human genes that show signs of strong negative selection during tumor evolution, suggesting that their functional integrity is essential for the growth and survival of tumor cells.

The Tumor Microenvironment as a Driving Force of Breast Cancer Stem Cell Plasticity

Simple Summary

Breast cancer stem cells are a subset of transformed cells that sustain tumor growth and can metastasize to secondary organs. Since metastasis accounts for most cancer deaths, it is of paramount importance to understand the cellular and molecular mechanisms that regulate this subgroup of cells. The tumor microenvironment (TME) is the habitat in which transformed cells evolve, and it is composed by many different cell types and the extracellular matrix (ECM). A body of evidence strongly indicates that microenvironmental cues modulate stemness in breast cancer, and that the coevolution of the TME and cancer stem cells determine the fate of breast tumors. In this review, we summarize the studies providing links between the TME and the breast cancer stem cell phenotype and we discuss their specific interactions with immune cell subsets, stromal cells, and the ECM.

Abstract

Tumor progression involves the co-evolution of transformed cells and the milieu in which they live and expand. Breast cancer stem cells (BCSCs) are a specialized subset of cells that sustain tumor growth and drive metastatic colonization. However, the cellular hierarchy in breast tumors is rather plastic, and the capacity to transition from one cell state to another depends not only on the intrinsic properties of transformed cells, but also on the interplay with their niches. It has become evident that the tumor microenvironment (TME) is a major player in regulating the BCSC phenotype and metastasis. The complexity of the TME is reflected in its number of players and in the interactions that they establish with each other. Multiple types of immune cells, stromal cells, and the extracellular matrix (ECM) form an intricate communication network with cancer cells, exert a highly selective pressure on the tumor, and provide supportive niches for BCSC expansion. A better understanding of the mechanisms regulating these interactions is crucial to develop strategies aimed at interfering with key BCSC niche factors, which may help reducing tumor heterogeneity and impair metastasis.

MSC-induced lncRNA AGAP2-AS1 promotes stemness and trastuzumab resistance through regulating CPT1 expression and fatty acid oxidation in breast cancer

Trastuzumab resistance has been becoming a major obstacle for treatment of HER-2-positive breast cancer patients. Increasing evidence suggests that mesenchymal stem cells (MSCs) play critical roles during the formation of drug resistance, however, the underlying mechanism is not well known. In this study, mass spectrometry, RNA pulldown and RNA immunoprecipitation assays were performed to verify the direct interactions among AGAP2-AS1 and other associated targets, such as human antigen R (HuR), miR-15a-5p, and carnitine palmitoyl transferase 1 (CPT1). In vitro and in vivo experimental assays were done to clarify the functional role of AGAP2-AS1 in trastuzumab resistance, stemness, and fatty acid oxidation (FAO). The results showed that MSC co-culture induced trastuzumab resistance. AGAP2-AS1 was upregulated in MSC-cultured cells, and knockdown of AGAP2-AS1 reversed the MSC-mediated trastuzumab resistance. Furthermore, MSC culture-induced AGAP2-AS1 regulates stemness and trastuzumab resistance via activating FAO. Mechanistically, AGAP2-AS1 is associated with HuR, and the AGAP2-AS1-HuR complex could directly bind to the CPT1, increasing its expression via improving RNA stability. In addition, AGAP2-AS1 could serve as ceRNA via sponging miR-15a-5p and releasing CPT1 mRNA. Clinically, increased expression of serum AGAP2-AS1 predicts poor response to trastuzumab treatment in breast cancer patients. In conclusion, MSC culture-induced AGAP2-AS1 caused stemness and trastuzumab resistance via promoting CPT1 expression and inducing FAO. Our results provide new insight of the role of MSCs in trastuzumab resistance and AGAP2-AS1 could be promising predictive biomarker and therapeutic target for HER-2+ breast cancer patients.

Galectin-9 is required for endometrial regenerative cells to induce long-term cardiac allograft survival in mice

Background

Endometrial regenerative cells (ERCs), a novel type of mesenchymal-like stem cells, were identified as an attractive candidate for immunoregulation and induction of cardiac allograft tolerance. However, the underlying mechanisms of ERCs in immune regulation still remain largely unclear. The present study is designed to determine whether the expression of Galectin-9 (Gal-9), a soluble tandem-repeat member of the galectin family, is crucial for ERC-based immunomodulation.

Methods

In this study, we measured Gal-9 expression on ERCs and then co-cultured Gal-9-ERCs, ERCs, and ERCs+lactose (Gal-9 blocker) with activated C57BL/6-derived splenocytes. Furthermore, we performed mouse heart transplantation between BALB/c (H-2^d) donor and C57BL/6 (H-2^b) recipient. ERCs were administrated 24 h after the surgery, either alone or in combination with rapamycin.

Results

Our data demonstrate that ERCs express Gal-9, and this expression is increased by IFN-γ stimulation in a dose-dependent manner. Moreover, both in vitro and in vivo results show that Gal-9-ERC-mediated therapy significantly suppressed Th1 and Th17 cell response, inhibited CD8⁺ T cell proliferation, abrogated B cell activation, decreased donor-specific antibody production, and enhanced the Treg population. The therapeutic effect of ERCs was further verified by their roles in prolonging cardiac allograft survival and alleviating graft pathological changes.

Conclusions

Taken together, these data indicate that Gal-9 is required for ERC-mediated immunomodulation and prevention of allograft rejection.

Cross talk between mesenchymal and glioblastoma stem cells: Communication beyond controversies

Mesenchymal stem cells (MSCs) can be isolated from bone marrow or other adult tissues (adipose tissue, dental pulp, amniotic fluid, and umbilical cord). In vitro, MSCs grow as adherent cells, display fibroblast-like morphology, and self-renew, undergoing specific mesodermal differentiation. High heterogeneity of MSCs from different origin, and differences in preparation techniques, make difficult to uniform their functional properties for therapeutic purposes. Immunomodulatory, migratory, and differentiation ability, fueled clinical MSC application in regenerative medicine, whereas beneficial effects are currently mainly ascribed to their secretome and extracellular vesicles. MSC translational potential in cancer therapy exploits putative anti-tumor activity and inherent tropism toward tumor sites to deliver cytotoxic drugs. However, controversial results emerged evaluating either the therapeutic potential or homing efficiency of MSCs, as both antitumor and protumor effects were reported. Glioblastoma (GBM) is the most malignant brain tumor and its development and aggressive nature is sustained by cancer stem cells (CSCs) and the identification of effective therapeutic is required. MSC dualistic action, tumor-promoting or tumor-targeting, is dependent on secreted factors and extracellular vesicles driving a complex cross talk between MSCs and GBM CSCs. Tumor-tropic ability of MSCs, besides providing an alternative therapeutic approach, could represent a tool to understand the biology of GBM CSCs and related paracrine mechanisms, underpinning MSC-GBM interactions. In this review, recent findings on the complex nature of MSCs will be highlighted, focusing on their elusive impact on GBM progression and aggressiveness by direct cell-cell interaction and via secretome, also facing the perspectives and challenges in treatment strategies.