Mesenchymal stem cells induce epithelial mesenchymal transition in melanoma by paracrine secretion of transforming growth factor-β

Tumorigenic effects of human mesenchymal stromal cells and fibroblasts on bladder cancer cells

Background

Patients with muscle-invasive bladder cancer face a poor prognosis due to rapid disease progression and chemoresistance. Thus, there is an urgent need for a new therapeutic treatment. The tumor microenvironment (TME) has crucial roles in tumor development, growth, progression, and therapy resistance. TME cells may also survive standard treatment of care and fire up disease recurrence. However, whether specific TME components have tumor-promoting or tumor-inhibitory properties depends on cell type and cancer entity. Thus, a deeper understanding of the interaction mechanisms between the TME and cancer cells is needed to develop new cancer treatment approaches that overcome therapy resistance. Little is known about the function and interaction between mesenchymal stromal cells (MSC) or fibroblasts (FB) as TME components and bladder cancer cells.

Methods

We investigated the functional impact of conditioned media (CM) from primary cultures of different donors of MSC or FB on urothelial carcinoma cell lines (UCC) representing advanced disease stages, namely, BFTC-905, VMCUB-1, and UMUC-3. Underlying mechanisms were identified by RNA sequencing and protein analyses of cancer cells and of conditioned media by oncoarrays.

Results

Both FB- and MSC-CM had tumor-promoting effects on UCC. In some experiments, the impact of MSC-CM was more pronounced. CM augmented the aggressive phenotype of UCC, particularly of those with epithelial phenotype. Proliferation and migratory and invasive capacity were significantly increased; cisplatin sensitivity was reduced. RNA sequencing identified underlying mechanisms and molecules contributing to the observed phenotype changes. NRF2 and NF-κB signaling was affected, contributing to improved cisplatin detoxification. Likewise, interferon type I signaling was downregulated and regulators of epithelial mesenchymal transition (EMT) were increased. Altered protein abundance of CXCR4, hyaluronan receptor CD44, or TGFβ-signaling was induced by CM in cancer cells and may contribute to phenotypical changes. CM contained high levels of CCL2/MCP-1, MMPs, and interleukins which are well known for their impact on other cancer entities.

Conclusions

The CM of two different TME components had overlapping tumor-promoting effects and increased chemoresistance. We identified underlying mechanisms and molecules contributing to the aggressiveness of bladder cancer cells. These need to be further investigated for targeting the TME to improve cancer therapy.

Immunohistochemical comparative analysis of tumor stem cell biomarkers in pleomorphic adenoma, adenoid cystic carcinoma and mucoepidermoid carcinoma of salivary glands

OBJECTIVE

This study aimed to compare the immunoexpression profile of tumor stem cell (TSC) biomarkers CD44, aldehyde dehydrogenase 1 (ALDH1), OCT4, and SOX2 in salivary gland tumors (SGTs).

STUDY DESIGN

Sixty tissue specimens of SGTs, including 20 pleomorphic adenomas, 20 adenoid cystic carcinomas (ACCs), and 20 mucoepidermoid carcinomas, in addition to 4 samples of normal glandular tissue, were subjected to immunohistochemistry. The expression of the biomarkers in the parenchyma and stroma was evaluated. Data were analyzed statistically by nonparametric tests (P < .05).

RESULTS

Higher parenchymal expression of ALDH1, OCT4, and SOX2 was observed in pleomorphic adenomas, ACCs, and mucoepidermoid carcinomas, respectively. Most ACCs did not express ALDH1. Higher immunoexpression of ALDH1 in major SGTs (P = .021) and of OCT4 in minor SGTs (P = .011) was found. Immunoexpression of SOX2 was related to lesions without myoepithelial differentiation (P < .001) and malignant behavior (P = .002). Furthermore, OCT4 was related to myoepithelial differentiation (P = .009). CD44 expression was related to a better prognosis. Stromal immunoexpressions of CD44, ALDH1, and OCT4 were higher in malignant SGTs.

CONCLUSIONS

Our findings suggest the participation of TSCs in the pathogenesis of SGTs. We emphasize the need for further investigations into the presence and role of TSCs in the stroma of these lesions.

Analysis of the Interaction of Human Neuroblastoma Cell-Derived Cytochalasin B Induced Membrane Vesicles with Mesenchymal Stem Cells Using Imaging Flow Cytometry

At present, there is an increasing interest in the potential role of extracellular vesicles (EVs), acting as multi-signal messengers of the tumor stroma, in the development and progression of tumor. Tumor cell-derived EVs are considered a potential vector for the targeted delivery of antitumor agents due to the ability to fuse with parental cells through endocytosis and release their contents into the cytoplasm of the recipient cell. Tumor cell-derived EVs could be also used for priming immune cells and therapeutic vaccine development. It is also known that mesenchymal stem cells (MSCs) have a tropism toward tumor niches. It is believed that MSC migration to the tumor is due to its inflammatory signaling. Presumably, with the accumulation of MSCs at tumor sites, these cells differentiate into pericytes or tumor-associated fibroblasts, thereby forming a supporting tumor growth microenvironment. However, besides the ability to promote tumor progression, MSCs can also suppress its growth by inhibiting proliferation and cell cycle progression, and angiogenesis. Thus, the further studies of the MSC role in TME and MSC interaction with other cells of the tumor stroma, including through EVs, are of particular interest. To increase the yield of vesicles the isolation method based on pharmacological disorganization of the actin cytoskeleton induced by treating with cytochalasin B was used in this study. In this investigation the interaction of SH-SY5Y neuroblastoma cell-derived membrane vesicles, obtained using cytochalasin B (CIMVs), with human bone marrow-derived MSCs was analyzed using imaging flow cytometry. Using transmission electron microscopy, it was shown that CIMVs have a size similar to that of natural microvesicles, which is 100–1000 nm. Using imaging flow cytometry, it was shown that after 24 h of co-cultivation 6% of the MSCs contained a large number of CIMVs, and 42% of the MSCs contained a small amount of CIMVs. Cultivation of MSCs with SH-SY5Y cell-derived CIMVs also induced dose-dependent decrease in the expression of CD markers typical for MSCs. Thus, the internalization of SH-SY5Y cell-derived CIMVs within MSCs and the ability of the CIMVs to modulate immunophenotype of the recipient cells were shown. However, further studies are required to determine the effect of CIMVs on pro- or antioncogenic phenotype and function of MSCs.

Signal pathways of melanoma and targeted therapy

Melanoma is the most lethal skin cancer that originates from the malignant transformation of melanocytes. Although melanoma has long been regarded as a cancerous malignancy with few therapeutic options, increased biological understanding and unprecedented innovations in therapies targeting mutated driver genes and immune checkpoints have substantially improved the prognosis of patients. However, the low response rate and inevitable occurrence of resistance to currently available targeted therapies have posed the obstacle in the path of melanoma management to obtain further amelioration. Therefore, it is necessary to understand the mechanisms underlying melanoma pathogenesis more comprehensively, which might lead to more substantial progress in therapeutic approaches and expand clinical options for melanoma therapy. In this review, we firstly make a brief introduction to melanoma epidemiology, clinical subtypes, risk factors, and current therapies. Then, the signal pathways orchestrating melanoma pathogenesis, including genetic mutations, key transcriptional regulators, epigenetic dysregulations, metabolic reprogramming, crucial metastasis-related signals, tumor-promoting inflammatory pathways, and pro-angiogenic factors, have been systemically reviewed and discussed. Subsequently, we outline current progresses in therapies targeting mutated driver genes and immune checkpoints, as well as the mechanisms underlying the treatment resistance. Finally, the prospects and challenges in the development of melanoma therapy, especially immunotherapy and related ongoing clinical trials, are summarized and discussed.

Research advances of secretory proteins in malignant tumors

Secretory proteins in tumor tissues are important components of the tumor microenvironment. Secretory proteins act on tumor cells or stromal cells or mediate interactions between tumor cells and stromal cells, thereby affecting tumor progression and clinical treatment efficacy. In this paper, recent research advances in secretory proteins in malignant tumors are reviewed.

Cancer stem cells, epigenetics, tumor microenvironment and future therapeutics in cutaneous malignant melanoma: a review

This review provides an overview of the current understanding of the ontogeny and biology of melanoma stem cells in cutaneous malignant melanoma. This article also summarizes and evaluates the current knowledge of the underlying epigenetic mechanisms, the regulation of melanoma progress by the tumor microenvironment as well as the therapeutic implications and applications of these novel insights, in the setting of personalized medicine. Unraveling the complex ecosystem of cutaneous malignant melanoma and the interplay between its components, aims to provide novel insights into the establishment of efficient therapeutic strategies.

Cellular and molecular biology of cancer stem cells in melanoma: Possible therapeutic implications

Malignant melanoma is a tumor characterized by a very high level of heterogeneity, responsible for its malignant behavior and ability to escape from standard therapies. In this review we highlight the molecular and biological features of the subpopulation of cancer stem cells (CSCs), well known to be characterized by self-renewal properties, deeply involved in triggering the processes of tumor generation, metastasis, progression and drug resistance. From the molecular point of view, melanoma CSCs are identified and characterized by the expression of stemness markers, such as surface markers, ATP-binding cassette (ABC) transporters, embryonic stem cells and intracellular markers. These cells are endowed with different functional features. In particular, they play pivotal roles in the processes of tumor dissemination, epithelial-to-mesenchymal transition (EMT) and angiogenesis, mediated by specific intracellular signaling pathways; moreover, they are characterized by a unique metabolic reprogramming. As reported for other types of tumors, the CSCs subpopulation in melanoma is also characterized by a low immunogenic profile as well as by the ability to escape the immune system, through the expression of a negative modulation of T cell functions and the secretion of immunosuppressive factors. These biological features allow melanoma CSCs to escape standard treatments, thus being deeply involved in tumor relapse. Targeting the CSCs subpopulation is now considered an attractive treatment strategy; in particular, combination treatments, based on both CSCs-targeting and standard drugs, will likely increase the therapeutic options for melanoma patients. The characterization of CSCs in liquid biopsies from single patients will pave the way towards precision medicine.

Adult Stem Cell Functioning in the Tumor Micro-Environment

Tumor progression from an expanded cell population in a primary location to disseminated lethal growths subverts attempts at cures. It has become evident that these steps are driven in a large part by cancer cell-extrinsic signaling from the tumor microenvironment (TME), one cellular component of which is becoming more appreciated for potential modulation of the cancer cells directly and the TME globally. That cell is a heterogenous population referred to as adult mesenchymal stem cells/multipotent stromal cells (MSCs). Herein, we review emerging evidence as to how these cells, both from distant sources, mainly the bone marrow, or local resident cells, can impact the progression of solid tumors. These nascent investigations raise more questions than they answer but paint a picture of an orchestrated web of signals and interactions that can be modulated to impact tumor progression.

Mesenchymal Stem Cells, Immune Cells and Tumor Cells Crosstalk: A Sinister Triangle in the Tumor Microenvironment

Mesenchymal Stem Cells [MSCs] are a heterogeneous population of fibroblast-like cells which maintain self-renewability and pluripotency. Many studies have demonstrated the immunomodulatory effects of MSCs on the innate and adaptive immune cells. As a result of interactions with tumor cells, microenvironment and immune-stimulating milieu, MSCs contribute to tumor progression by several mechanisms, including sustained proliferative signal in cancer stem cells [CSCs], inhibition of tumor cell apoptosis, transition to tumor-associated fibroblasts [TAFs], promotion of angiogenesis, stimulation of epithelial-mesenchymal transition [EMT], suppression of immune responses, and consequential promotion of tumor metastasis. Here, we present an overview of the latest findings on Janusfaced roles that MSCs play in the tumor microenvironment [TME], with a concise focus on innate and adaptive immune responses.

Roles of genetic and microenvironmental factors in cancer epithelial-to-mesenchymal transition and therapeutic implication

Epithelial-to-mesenchymal transition (EMT) is a process in which epithelial cells lose their cell-cell contacts resulting in the formation of mesenchymal cells with migratory properties. Increasing evidence indicate EMT plays a key role in the invasion, metastasis and therapeutic resistance of cancer and maintenance of the phenotype of cancer stem cells (CSCs), which makes the prognosis of patients worse. The progression of cancer from epithelial tissue towards a malignant phenotype is driven by multiple factors that remodel the tissue architecture. This review summarizes and analyzes current studies of genetic and microenvironmental factors in inducing and maintaining cancer EMT and therapeutic implications. This will enable a better understanding of the contribution of EMT-associated factors to cancer progression and highlights that genetic factors and tumor microenvironment responsible for EMT could be used as attractive targets for therapeutic intervention.

T-type calcium channels drive migration/invasion in BRAFV600E melanoma cells through Snail1

Melanoma is a malignant tumor derived from melanocytes. Once disseminated, it is usually highly resistant to chemotherapy and is associated with poor prognosis. We have recently reported that T-type calcium channels (TTCCs) are overexpressed in melanoma cells and play an important role in melanoma progression. Importantly, TTCC pharmacological blockers reduce proliferation and deregulate autophagy leading to apoptosis. Here, we analyze the role of autophagy during migration/invasion of melanoma cells. TTCC Cav3.1 and LC3-II proteins are highly expressed in BRAFV600E compared with NRAS mutant melanomas, both in cell lines and biopsies. Chloroquine, pharmacological blockade, or gene silencing of TTCCs inhibit the autophagic flux and impair the migration and invasion capabilities, specifically in BRAFV600E melanoma cells. Snail1 plays an important role in motility and invasion of melanoma cells. We show that Snail1 is strongly expressed in BRAFV600E melanoma cells and patient biopsies, and its expression decreases when autophagy is blocked. These results demonstrate a role of Snail1 during BRAFV600E melanoma progression and strongly suggest that targeting macroautophagy and, particularly TTCCs, might be a good therapeutic strategy to inhibit metastasis of the most common melanoma type (BRAFV600E).

Mesenchymal stromal cell engagement in cancer cell epithelial to mesenchymal transition

Due to coexistence of stromal and epithelial tumor cells, their dynamic interactions have been widely recognized as significant cellular components to the tumor tissue integrity. Initiation and outcome of epithelial to mesenchymal transition (EMT) in tumor cells are dependent on their interaction with adjacent or recruited mesenchymal stromal cells (MSCs). A plethora of mechanisms are involved in MSCs-controlled employment of the developmental processes of EMT that contribute to loss of epithelial cell phenotype and acquisition of stemness, invasiveness and chemoresistance of tumor cells. Interplay of MSCs with tumor cells, including interchange of soluble biomolecules, plasma membrane structures, cytoplasmic content, and organelles, is established through cell-cell contact and/or by means of paracrine signaling. The main focus of this review is to summarize knowledge about involvement of MSCs in cancer cell EMT. Understanding the underlying cellular and molecular mechanism involved in the interplay between MSCs and cancer EMT is essential for development of effective therapy approaches, which in combination with current treatments may improve the control of tumor progression. Developmental Dynamics 247:359-367, 2018. © 2017 Wiley Periodicals, Inc.

Secreted molecules inducing epithelial-to-mesenchymal transition in cancer development

The epithelial-mesenchymal transition (EMT) is a biologic process that allows a polarized epithelial cell to undergo multiple biochemical changes that enable it to assume a mesenchymal cell phenotype. EMT is involved in embryo development, wound healing, tissue regeneration, organ fibrosis and has also been proposed as the critical mechanism for the acquisition of malignant phenotypes by epithelial cancer cells. These cells have been shown to acquire a mesenchymal phenotype when localized at the invasive front of primary tumours increasing aggressiveness, invasiveness, metastatic potential and resistance to chemotherapy. There is now increasing evidence demonstrating that a crucial role in the development of this process is played by factors secreted by cells of the tumour microenvironment or by the tumour cells themselves. This review summarises the current knowledge of EMT induction in cancer by paracrine or autocrine mechanisms, by exosomes or free proteins and miRNAs.