Downregulation of CXCL12 in mesenchymal stromal cells by TGFβ promotes breast cancer metastasis

Emerging roles for stromal cells in bone metastasis

The skeleton is a common site of cancer metastasis and malignancy with the resultant lesions often being incurable. Interactions between metastatic cancer cells and the bone microenvironment are critical for cancer cell survival, outgrowth, and progression. Mesenchymal Stem Cells (MSCs) are an essential stromal cell type in bone that are appreciated for their impacts on cancer-induced bone disease, however, newer evidence suggests that MSCs possess extensive roles in cancer-bone crosstalk, including cancer cell dormancy, metabolic demands, and immune-oncology. Emerging evidence has also identified the importance of MSC tissue source and the influence of ageing when studying MSC biology. Combining these considerations together with developing technologies such as spatial transcriptomics will contribute to defining the molecular mechanisms underlying complex stroma-cancer interactions in bone and assist with identification of therapeutically tractable targets.

Signaling crosstalk between mesenchymal stem cells and tumor cells: Implications for tumor suppression or progression

Mesenchymal stem cells (MSCs) have been extensively used in various therapeutic applications over the last two decades, particularly in regenerative medicine and cancer treatment. MSCs have the ability to differentiate into mesodermal and non-mesodermal lineages, which makes them a popular choice in tissue engineering and regenerative medicine. Studies have shown that MSCs have inherent tumor-suppressive properties and can affect the behavior of multiple cells contributing to tumor development. Additionally, MSCs possess a tumor tropism property and have a hypoimmune nature. The intrinsic features of MSCs along with their potential to undergo genetic manipulation and be loaded with various anticancer therapeutics have motivated researchers to use them in different cancer therapy approaches without considering their complex dynamic biological aspects. However, despite their desirable features, several reports have shown that MSCs possess tumor-supportive properties. These contradictory results signify the sophisticated nature of MSCs and warn against the potential therapeutic applications of MSCs. Therefore, researchers should meticulously consider the biological properties of MSCs in preclinical and clinical studies to avoid any undesirable outcomes. This manuscript reviews preclinical studies on MSCs and cancer from the last two decades, discusses how MSC properties affect tumor progression and explains the mechanisms behind tumor suppressive and supportive functions. It also highlights critical cellular pathways that could be targeted in future studies to improve the safety and effectiveness of MSC-based therapies for cancer treatment. The insights obtained from this study will pave the way for further clinical research on MSCs and development of more effective cancer treatments.

Nanoparticles for the Treatment of Bone Metastasis in Breast Cancer: Recent Advances and Challenges

Although the frequency of bone metastases from breast cancer has increased, effective treatment is lacking, prompting the development of nanomedicine, which involves the use of nanotechnology for disease diagnosis and treatment. Nanocarrier drug delivery systems offer several advantages over traditional drug delivery methods, such as higher reliability and biological activity, improved penetration and retention, and precise targeting and delivery. Various nanoparticles that can selectively target tumor cells without causing harm to healthy cells or organs have been synthesized. Recent advances in nanotechnology have enabled the diagnosis and prevention of metastatic diseases as well as the ability to deliver complex molecular "cargo" particles to metastatic regions. Nanoparticles can modulate systemic biodistribution and enable the targeted accumulation of therapeutic agents. Several delivery strategies are used to treat bone metastases, including untargeted delivery, bone-targeted delivery, and cancer cell-targeted delivery. Combining targeted agents with nanoparticles enhances the selective delivery of payloads to breast cancer bone metastatic lesions, providing multiple delivery advantages for treatment. In this review, we describe recent advances in nanoparticle development for treating breast cancer bone metastases.

Tumor-associated macrophages promoting PD-L1 expression in infiltrating B cells through the CXCL12/CXCR4 axis in human hepatocellular carcinoma

The inflammation-related tumor microenvironment (TME) is one of the major driving forces of hepatocarcinogenesis. We aimed to investigate cell-to-cell communication among Hepatocellular Carcinoma (HCC) through re-analyzing HCC single-cell RNA-seq data, and to confirm such cellular interaction through in vitro and in vivo study. We found a subset of Regulatory B cells with PD-L1 expression (PD-L1+ Bregs), mainly located in adjacent HCC tissues. In co-localization with PD-L1+ Bregs, a subset of Tumor Associated Macrophages with high expression of CXCL12 (CXCL12+ TAMs) was also mainly located in adjacent HCC tissues. Moreover, CXCL12+ TAMs can be stimulated in vitro using an HCC conditional medium. Using CellChat analysis and Multiplex Immunohistochemistry staining (mIHC), CXCL12+ TAMs were found to be first recruited by Cancer-Associated Fibroblasts (CAFs) through a CD74/macrophage migration inhibitory factor (MIF) pattern, and further differentiated into TGF-β-enriched tissues. Furthermore, CXCL12+ TAMs recruited PD-L1+ Bregs via the CXCL12/CXCR4 axis, and CXCR4 expression was significantly positively correlated to PD-L1 expression in PD-L1+ Bregs. At last, we confirmed the communications among CAFs, Macrophages and B cells and their tumor-promoting effects by using an orthotopic mouse model of HCC. Immunosuppressive HCC TME involving cell-to-cell communications comprised MIF-secreting CAFs, CXCL12-secreting TAMs, and PD-L1-producing Bregs, and their regulation could be promising therapeutic targets in future immunotherapy for human HCC.

An emerging paradigm of CXCL12 involvement in the metastatic cascade

The chemokine CXCL12, also known as stromal cell-derived factor 1 (SDF1), has emerged as a pivotal regulator in the intricate molecular networks driving cancer progression. As an influential factor in the tumor microenvironment, CXCL12 plays a multifaceted role that spans beyond its traditional role as a chemokine inducing invasion and metastasis. Indeed, CXCL12 has been assigned functions related to epithelial-to-mesenchymal transition, cancer cell stemness, angiogenesis, and immunosuppression, all of which are currently viewed as specialized biological programs contributing to the "metastatic cascade" among other cancer hallmarks. Its interaction with its cognate receptor, CXCR4, initiates a cascade of events that not only shapes the metastatic potential of tumor cells but also defines the niches within the secondary organs that support metastatic colonization. Given the profound implications of CXCL12 in the metastatic cascade, understanding its mechanistic underpinnings is of paramount importance for the targeted elimination of rate-limiting steps in the metastatic process. This review aims to provide a comprehensive overview of the current knowledge surrounding the role of CXCL12 in cancer metastasis, especially its molecular interactions rationalizing its potential as a therapeutic target.

High density of CXCL12-positive immune cell infiltration predicts chemosensitivity and recurrence-free survival in ovarian carcinoma

BACKGROUND

Ovarian carcinoma is the most lethal gynecologic malignancy because of its late diagnosis, extremely high recurrence rate, and limited curative treatment options. In clinical practice, high-grade serous carcinoma (HGSC) predominates due to its frequency, high aggressiveness, and rapid development of drug resistance. Recent evidence suggests that CXCL12 is an important immunological factor in ovarian cancer progression. Therefore, we investigated the predictive and prognostic significance of the expression of this chemokine in tumor and immune cells in patients with HGSC.

METHODS

We studied a cohort of 47 primary high-grade serous ovarian carcinomas and their associated recurrences. A tissue microarray was constructed to evaluate the CXCL12 immunostained tumor tissue. CXCL12 expression was evaluated and statistically analyzed to correlate clinicopathologic data, overall survival, and recurrence-free survival.

RESULTS

A high proportion of CXCL12 + positive immune cells in primary ovarian serous carcinoma correlated significantly with chemosensitivity (p = 0.005), overall survival (p = 0.021), and longer recurrence-free survival (p = 0.038). In recurrent disease, high expression of CXCL12 was also correlated with better overall survival (p = 0.040). Univariate and multivariate analysis revealed that high CXCL12 + tumor-infiltrating immune cells (TICs) (HR 0.99, p = 0.042, HR 0.99, p = 0.023, respectively) and combined CXCL12 + /CD66b + infiltration (HR 0.15, p = 0.001, HR 0.13, p = 0.001, respectively) are independent favorable predictive markers for recurrence-free survival.

CONCLUSION

A high density of CXCL12 + TICs predicts a good response to chemotherapy, leading to a better overall survival and a longer recurrence-free interval. Moreover, with concomitant high CXCL12/CD66b TIC density, it is an independent favorable predictor of recurrence-free survival in patients with ovarian carcinoma.

Establishment and Characterization of Free-Floating 3D Macrophage Programming Model in the Presence of Cancer Cell Spheroids

Reprogramming of tumor-associated macrophages (TAMs) is a promising strategy for cancer immunotherapy. Several studies have shown that cancer cells induce/support the formation of immunosuppressive TAMs phenotypes. However, the specific factors that orchestrate this immunosuppressive process are unknown or poorly studied. In vivo studies are expensive, complex, and ethically constrained. Therefore, 3D cell interaction models could become a unique framework for the identification of important TAMs programming factors. In this study, we have established and characterized a new in vitro 3D model for macrophage programming in the presence of cancer cell spheroids. First, it was demonstrated that the profile of cytokines, chemokines, and surface markers of 3D-cultured macrophages did not differ conceptually from monolayer-cultured M1 and M2-programmed macrophages. Second, the possibility of reprogramming macrophages in 3D conditions was investigated. In total, the dynamic changes in 6 surface markers, 11 cytokines, and 22 chemokines were analyzed upon macrophage programming (M1 and M2) and reprogramming (M1→M2 and M2→M1). According to the findings, the reprogramming resulted in a mixed macrophage phenotype that expressed both immunosuppressive and anti-cancer immunostimulatory features. Third, cancer cell spheroids were shown to stimulate the production of immunosuppressive M2 markers as well as pro-tumor cytokines and chemokines. In summary, the newly developed 3D model of cancer cell spheroid/macrophage co-culture under free-floating conditions can be used for studies on macrophage plasticity and for the development of targeted cancer immunotherapy.

The diverse effects of transforming growth factor-β and SMAD signaling pathways during the CTL response

Cytotoxic T lymphocytes (CTLs) play an important role in defense against infections with intracellular pathogens and anti-tumor immunity. Efficient migration is required to locate and destroy infected cells in different regions of the body. CTLs accomplish this task by differentiating into specialized subsets of effector and memory CD8 T cells that traffic to different tissues. Transforming growth factor-beta (TGFβ) belongs to a large family of growth factors that elicit diverse cellular responses via canonical and non-canonical signaling pathways. Canonical SMAD-dependent signaling pathways are required to coordinate changes in homing receptor expression as CTLs traffic between different tissues. In this review, we discuss the various ways that TGFβ and SMAD-dependent signaling pathways shape the cellular immune response and transcriptional programming of newly activated CTLs. As protective immunity requires access to the circulation, emphasis is placed on cellular processes that are required for cell-migration through the vasculature.

Impact of the Cancer Cell Secretome in Driving Breast Cancer Progression

Breast cancer is a complex and heterogeneous disease resulting from the accumulation of genetic and epigenetic alterations in breast epithelial cells. Despite remarkable progress in diagnosis and treatment, breast cancer continues to be the most prevalent cancer affecting women worldwide. Recent research has uncovered a compelling link between breast cancer onset and the extracellular environment enveloping tumor cells. The complex network of proteins secreted by cancer cells and other cellular components within the tumor microenvironment has emerged as a critical player in driving the disease's metastatic properties. Specifically, the proteins released by the tumor cells termed the secretome, can significantly influence the progression and metastasis of breast cancer. The breast cancer cell secretome promotes tumorigenesis through its ability to modulate growth-associated signaling pathways, reshaping the tumor microenvironment, supporting pre-metastatic niche formation, and facilitating immunosurveillance evasion. Additionally, the secretome has been shown to play a crucial role in drug resistance development, making it an attractive target for cancer therapy. Understanding the intricate role of the cancer cell secretome in breast cancer progression will provide new insights into the underlying mechanisms of this disease and aid in the development of more innovative therapeutic interventions. Hence, this review provides a nuanced analysis of the impact of the cancer cell secretome on breast cancer progression, elucidates the complex reciprocal interaction with the components of the tumor microenvironment and highlights emerging therapeutic opportunities for targeting the constituents of the secretome.

Novel strategies for cancer immunotherapy: counter-immunoediting therapy

The advent of immunotherapy has made an indelible mark on the field of cancer therapy, especially the application of immune checkpoint inhibitors in clinical practice. Although immunotherapy has proven its efficacy and safety in some tumors, many patients still have innate or acquired resistance to immunotherapy. The emergence of this phenomenon is closely related to the highly heterogeneous immune microenvironment formed by tumor cells after undergoing cancer immunoediting. The process of cancer immunoediting refers to the cooperative interaction between tumor cells and the immune system that involves three phases: elimination, equilibrium, and escape. During these phases, conflicting interactions between the immune system and tumor cells result in the formation of a complex immune microenvironment, which contributes to the acquisition of different levels of immunotherapy resistance in tumor cells. In this review, we summarize the characteristics of different phases of cancer immunoediting and the corresponding therapeutic tools, and we propose normalized therapeutic strategies based on immunophenotyping. The process of cancer immunoediting is retrograded through targeted interventions in different phases of cancer immunoediting, making immunotherapy in the context of precision therapy the most promising therapy to cure cancer.

Recent advancements to engineer mesenchymal stem cells and their extracellular vesicles for targeting and destroying tumors

Mesenchymal stem cells (MSCs) have the ability to migrate into tumor sites and release growth factors to modulate the tumor microenvironment. MSC therapy have shown a dual role in cancers, promoting or inhibiting. However, MSCs could be used as a carrier of anticancer agents for targeted tumor therapy. Recent technical improvements also allow engineering MSCs to improve tumor-targeting properties, protect anticancer agents, and decrease the cytotoxicity of drugs. While some of MSC functions are mediated through their secretome, MSCs-derived extracellular vesicles (EVs) are also proposed as a possible viechle for cancer therapy. EVs allow efficient loading of anticancer agents and have an intrinsic ability to target tumor cells, making them suitable for targeted therapy of tumors. In addition, the specificity and selectivity of EVs to the tumor sites could be enhanced by surface modification. In this review, we addressed the current approaches used for engineering MSCs and EVs to effectively target tumor sites and deliver anticancer agents.

CXCL12 is expressed by skeletal muscle cells in tongue oral squamous cell carcinoma

BACKGROUND

The CXCL12/CXCR4 axis plays a pivotal role in the progression of various malignancies, including oral squamous cell carcinoma (OSCC). In this study, we aimed to clarify the biological and clinical significance of CXCL12 in the tumor microenvironment of OSCCs.

METHODS

Publicly available single-cell RNA-sequencing (RNA-seq) datasets were used to analyze CXCL12 expression in head and neck squamous cell carcinomas (HNSCC). Immunohistochemical analysis of CXCL12, α-smooth muscle antigen (α-SMA), fibroblast activation protein (FAP) and CD8 was performed in a series of 47 surgically resected primary tongue OSCCs. Human skeletal muscle cells were co-cultured with or without OSCC cells, after which CXCL12 expression was analyzed using quantitative reverse-transcription PCR.

RESULTS

Analysis of the RNA-seq data suggested CXCL12 is abundantly expressed in stromal cells within HNSCC tissue. Immunohistochemical analysis showed that in grade 1 primary OSCCs, CXCL12 is expressed in both tumor cells and muscle cells. By contrast, grade 3 tumors were characterized by disruption of muscle structure and reduced CXCL12 expression. Quantitative analysis of CXCL12-positive areas within tumors revealed that reduced CXCL12 expression correlated with poorer overall survival. Levels of CXCL12 expression tended to inversely correlate α-SMA expression and positively correlate with infiltration by CD8+ lymphocytes, though these relations did not reach statistical significance. CXCL12 was significantly upregulated in muscle cells co-cultured with OSCC cells.

CONCLUSION

Our results suggest that tongue OSCC cells activate CXCL12 expression in muscle cells, which may contribute to tumor progression. However, CXCL12 is reduced in advanced OSCCs due to muscle tissue destruction.

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.

Characteristics and Resistance to Cisplatin of Human Neuroblastoma Cells Co-Cultivated with Immune and Stromal Cells

We investigated the features of the morphology and cytokine profiles of neuroblastoma SH-SY5Y cells, bone marrow-derived mesenchymal stromal/stem cells (BM-MSCs), and peripheral blood mononuclear cells (PBMCs) in double (BM-MSCs + SH-SY5Y cells) and triple (BM-MSCs + SH-SY5Y cells + PBMCs) co-cultures incubated on plastic and Matrigel. Cells in the co-cultures communicated by vesicular transport and by exchanging membrane and cytoplasmic components. The cytokine profile of double and triple co-cultures incubated on Matrigel and plastic had differences and showed the highest concentration of a number of chemokines/cytokines, such as CXCL8/IL-8, I-TAC/CXCL11, IP10/CXCL10, MDC/CCL22, MIP-1α/CCL3, IL-1β, ENA-78/CXCL5, Gro-α/CXCL1, MCP-1/CCL2, TERC/CCL25, CXCL8/IL-8, and IL-6. High concentrations of inflammatory chemokines/cytokines in the conditioned medium of triple co-culture form a chronic inflammation, which brings the presented co-cultivation system closer to a natural tumor. Triple co-cultures were more resistant to cisplatin (CDDP) than the double- and monoculture of SH-SY5Y. The mRNA levels of BCL2, BCL2L1, RAC1, CAV1, CASP3, and BAX genes were changed in cells after co-culturing and CDDP treatment in double and triple co-cultures. The expression of the BCL2, BAX, CAV1, and CASP3 proteins in SH-SY5Y cells after the triple co-culture and CAV1 and BAX protein expression in SH-SY5Y cells after the double co-culture were determined. This study demonstrated the nature of the cellular interactions between components of tumor niche and the intercellular influence on chemoresistance observed in our tumor model, which should enable the development of novel test systems for anti-tumor agents.

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.

Adipose Tissue-Derived Mesenchymal Stromal/Stem Cells, Obesity and the Tumor Microenvironment of Breast Cancer

Breast cancer is the most frequently diagnosed cancer and a common cause of cancer-related death in women. It is well recognized that obesity is associated with an enhanced risk of more aggressive breast cancer as well as reduced patient survival. Adipose tissue is the major microenvironment of breast cancer. Obesity changes the composition, structure, and function of adipose tissue, which is associated with inflammation and metabolic dysfunction. Interestingly, adipose tissue is rich in ASCs/MSCs, and obesity alters the properties and functions of these cells. As a key component of the mammary stroma, ASCs play essential roles in the breast cancer microenvironment. The crosstalk between ASCs and breast cancer cells is multilateral and can occur both directly through cell-cell contact and indirectly via the secretome released by ASC/MSC, which is considered to be the main effector of their supportive, angiogenic, and immunomodulatory functions. In this narrative review, we aim to address the impact of obesity on ASCs/MSCs, summarize the current knowledge regarding the potential pathological roles of ASCs/MSCs in the development of breast cancer, discuss related molecular mechanisms, underline the possible clinical significance, and highlight related research perspectives. In particular, we underscore the roles of ASCs/MSCs in breast cancer cell progression, including proliferation and survival, angiogenesis, migration and invasion, the epithelial-mesenchymal transition, cancer stem cell development, immune evasion, therapy resistance, and the potential impact of breast cancer cells on ASCS/MSCs by educating them to become cancer-associated fibroblasts. We conclude that ASCs/MSCs, especially obese ASCs/MSCs, may be key players in the breast cancer microenvironment. Targeting these cells may provide a new path of effective breast cancer treatment.

A comprehensive bioinformatics analysis to identify potential prognostic biomarkers among CC and CXC chemokines in breast cancer

Breast cancer (BC) is a major human health problem due to its increasing incidence and mortality rate. CC and CXC chemokines are associated with tumorigenesis and the progression of many cancers. Since the prognostic values of CC and CXC families' expression in various types of cancers are becoming increasingly evident, we aimed to conduct a comprehensive bioinformatics analysis elucidating the prognostic values of the CC and CXC families in BC. Therefore, TCGA, UALCAN, Kaplan–Meier plotter, bc-GenExMiner, cBioPortal, STRING, Enrichr, and TIMER were utilized for analysis. We found that high levels of CCL4/5/14/19/21/22 were associated with better OS and RFS, while elevated expression of CCL24 was correlated with shorter OS in BC patients. Also, high levels of CXCL9/13 indicated longer OS, and enhanced expression of CXCL12/14 was linked with better OS and RFS in BC patients. Meanwhile, increased transcription levels of CXCL8 were associated with worse OS and RFS in BC patients. In addition, our results showed that CCL5, CCL8, CCL14, CCL20, CCL27, CXCL4, and CXCL14 were notably correlated with the clinical outcomes of BC patients. Our findings provide a new point of view that may help the clinical application of CC and CXC chemokines as prognostic biomarkers in BC.

Biological Role of Tumor/Stromal CXCR4-CXCL12-CXCR7 in MITO16A/MaNGO-OV2 Advanced Ovarian Cancer Patients

Simple Summary

Despite rapid progress in the research on epithelial ovarian cancer (EOC), it is usually diagnosed during the advanced stage with only 30% of patients surviving longer than 5 years. This is the first study in which the whole CXCR4-CXCL12-CXCR7 axis was systematically evaluated in tumor and stromal cells, through rigorous statistical methods in a prospective clinical trial. CXCL12 expression in cancer cells is associated with worse progression-free survival in stage III EOC patients, and deserves further attention as a potential prognostic and therapeutic target.

Abstract

This study investigated the prognostic role of the CXCR4-CXCL12-CXCR7 axis in advanced epithelial ovarian cancer (EOC) patients receiving first-line treatment within the MITO16A/MaNGO-OV2 phase-IV trial. CXCR4-CXCL12-CXCR7 expression was evaluated in the epithelial and stromal component of 308 EOC IHC-stained tumor samples. The statistical analysis focused on biomarkers’ expression, their association with other variables and prognostic value. Zero-inflated tests, shrinkage, bootstrap procedures, and multivariable models were applied. The majority of EOC (75.0%) expressed CXCR4 and CXCR7, 56.5% expressed the entire CXCR4-CXCL12-CXCR7 axis, while only 4.6% were negative for CXCL12 and its cognate receptors, in regard to the epithelial component. Stromal CXCL12 and CXCR7, expressed in 11.2% and 65.5%, respectively, were associated with the FIGO stage. High CXCL12 in epithelial cancer cells was associated with shorter progression-free and overall survival. However, after adjusting for overfitting due to best cut-off multiplicity testing, the significance was lost. This is a wide-ranging, prospective study in which CXCR4-CXCL12-CXCR7 were systematically evaluated in epithelial and stromal components, in selected stage III-IV EOC. Although CXCL12 was not prognostic, epithelial expression identified high-risk FIGO stage III patients for PFS. These data suggest that it might be worth studying the CXCL12 axis as a therapeutic target to improve treatment efficacy in EOC patients.

Colorectal Cancer: The Contribution of CXCL12 and Its Receptors CXCR4 and CXCR7

Colorectal cancer is one of the most common cancers, and diagnosis at late metastatic stages is the main cause of death related to this cancer. This progression to metastasis is complex and involves different molecules such as the chemokine CXCL12 and its two receptors CXCR4 and CXCR7. The high expression of receptors in CRC is often associated with a poor prognosis and aggressiveness of the tumor. The interaction of CXCL12 and its receptors activates signaling pathways that induce chemotaxis, proliferation, migration, and cell invasion. To this end, receptor inhibitors were developed, and their use in preclinical and clinical studies is ongoing. This review provides an overview of studies involving CXCR4 and CXCR7 in CRC with an update on their targeting in anti-cancer therapies.

Chemokines in Triple-Negative Breast Cancer Heterogeneity: New Challenges for Clinical Implications

Tumor heterogeneity is a hallmark of cancer and one of the primary causes of resistance to therapies. Triple-negative breast cancer (TNBC), which accounts for 15% to 20% of all breast cancers and is the most aggressive subtype, is very diverse, connected to metastatic potential and response to therapy. It is a very diverse disease at the molecular, pathologic, and clinical levels. TNBC is substantially more likely to recur and has a worse overall survival rate following diagnosis than other breast cancer subtypes. Chemokines, low molecular weight proteins that stimulate chemotaxis, have been shown to control the cues responsible for TNBC heterogeneity. In this review, we have focused on tumor heterogeneity and the role of chemokines in modulating tumor heterogeneity, since this is the most critical issue in treating TNBC. Additionally, we examined numerous cues mediated by chemokine networks that contribute to the heterogeneity of TNBC. Recent developments in our knowledge of the chemokine networks that regulate TNBC heterogeneity may pave the door for developing difficult-to-treat TNBC treatment options.

Reversing chemokine/chemokine receptor mismatch to enhance the antitumor efficacy of CAR-T cells

Currently, the antitumor efficacy of chimeric antigen receptor T cells in solid tumors is modest. Both chemokines and their receptors play a key role in the proliferation of cancer cells, tumor angiogenesis, organ-selective metastasis and migration of immune cells to solid tumors. Unfortunately, frequent chemokine/chemokine receptor 'mismatch' between effector cells and the tumor microenvironment results in inefficient T-cell infiltration and antitumor efficacy. Thus, reversing the 'mismatch' of chemokines and chemokine receptors appears to be a promising method for promoting T-cell infiltration into the tumor and enhancing their antitumor efficacy. In this review, we discuss functions of the chemokine/chemokine receptor axis in cancer immunity and the current understanding, challenges and prospects for improving the effect of chimeric antigen receptor T cells by reversing the mismatch between chemokines and chemokine receptors.

The Effect of Hypoxic and Normoxic Culturing Conditions in Different Breast Cancer 3D Model Systems

The field of 3D cell cultures is currently emerging, and material development is essential in striving toward mimicking the microenvironment of a native tissue. By using the response of reporter cells to a 3D environment, a comparison between materials can be assessed, allowing optimization of material composition and microenvironment. Of particular interest, the response can be different in a normoxic and hypoxic culturing conditions, which in turn may alter the conclusion regarding a successful recreation of the microenvironment. This study aimed at determining the role of such environments to the conclusion of a better resembling cell culture model to native tissue. Here, the breast cancer cell line MCF7 was cultured in normoxic and hypoxic conditions on patient-derived scaffolds and compared at mRNA and protein levels to cells cultured on 3D printed scaffolds, Matrigel, and conventional 2D plastics. Specifically, a wide range of mRNA targets (40), identified as being regulated upon hypoxia and traditional markers for cell traits (cancer stem cells, epithelial-mesenchymal transition, pluripotency, proliferation, and differentiation), were used together with a selection of corresponding protein targets. 3D cultured cells were vastly different to 2D cultured cells in gene expression and protein levels on the majority of the selected targets in both normoxic and hypoxic culturing conditions. By comparing Matrigel and 3DPS-cultured cells to cells cultured on patient-derived scffolds, differences were also noted along all categories of mRNA targets while specifically for the GLUT3 protein. Overall, cells cultured on patient-derived scaffolds closely resembled cells cultured on 3D printed scaffolds, contrasting 2D and Matrigel-cultured cells, regardless of a normoxic or hypoxic culturing condition. Thus, these data support the use of either a normoxic or hypoxic culturing condition in assays using native tissues as a blueprint to optimize material composition.

The Relationship Between Mesenchymal Stem Cells and Tumor Dormancy

Tumor dormancy, a state of tumor, is clinically undetectable and the outgrowth of dormant tumor cells into overt metastases is responsible for cancer-associated deaths. However, the dormancy-related molecular mechanism has not been clearly described. Some researchers have proposed that cancer stem cells (CSCs) and disseminated tumor cells (DTCs) can be seen as progenitor cells of tumor dormancy, both of which can remain dormant in a non-permissive soil/niche. Nowadays, research interest in the cancer biology field is skyrocketing as mesenchymal stem cells (MSCs) are capable of regulating tumor dormancy, which will provide a unique therapeutic window to cure cancer. Although the influence of MSCs on tumor dormancy has been investigated in previous studies, there is no thorough review on the relationship between MSCs and tumor dormancy. In this paper, the root of tumor dormancy is analyzed and dormancy-related molecular mechanisms are summarized. With an emphasis on the role of the MSCs during tumor dormancy, new therapeutic strategies to prevent metastatic disease are proposed, whose clinical application potentials are discussed, and some challenges and prospects of the studies of tumor dormancy are also described.

Stimulated Expression of CXCL12 in Adrenocortical Carcinoma by the PPARgamma Ligand Rosiglitazone Impairs Cancer Progression

Adrenocortical carcinoma (ACC) is a rare malignancy with poor prognosis when metastatic and scarce treatment options in the advanced stages. In solid tumors, the chemokine CXCL12/CXCR4 axis is involved in the metastatic process. We demonstrated that the human adrenocortex expressed CXCL12 and its cognate receptors CXCR4 and CXCR7, not only in physiological conditions, but also in ACC, where the receptors’ expression was higher and the CXCL12 expression was lower than in the physiological conditions. In a small pilot cohort of 22 ACC patients, CXCL12 negatively correlated with tumor size, stage, Weiss score, necrosis, and mitotic activity. In a Kaplan–Meier analysis, the CXCL12 tumor expression significantly predicted disease-free, progression-free, and overall survival. In vitro treatment of the primary ACC H295R and of the metastatic MUC-1 cell line with the PPARγ-ligand rosiglitazone (RGZ) dose-dependently reduced proliferation, resulting in a significant increase in CXCL12 and a decrease in its receptors in the H295R cells only, with no effect on the MUC-1 levels. In ACC mouse xenografts, tumor growth was inhibited by the RGZ treatment before tumor development (prevention-setting) and once the tumor had grown (therapeutic-setting), similarly to mitotane (MTT). This inhibition was associated with a significant suppression of the tumor CXCR4/CXCR7 and the stimulation of human CXCL12 expression. Tumor growth correlated inversely with CXCL12 and positively with CXCR4 expression, suggesting that local CXCL12 may impair the primary tumor cell response to the ligand gradient that may contribute to driving the tumor progression. These findings indicate that CXCL12/CXCR4 may constitute a potential target for anti-cancer agents such as rosiglitazone in the treatment of ACC.

Chemokine signaling in cancer-stroma communications

Cancer is a multi-faceted disease in which spontaneous mutation(s) in a cell leads to the growth and development of a malignant new organ that if left undisturbed will grow in size and lead to eventual death of the organism. During this process, multiple cell types are continuously releasing signaling molecules into the microenvironment, which results in a tangled web of communication that both attracts new cell types into and reshapes the tumor microenvironment as a whole. One prominent class of molecules, chemokines, bind to specific receptors and trigger directional, chemotactic movement in the receiving cell. Chemokines and their receptors have been demonstrated to be expressed by almost all cell types in the tumor microenvironment, including epithelial, immune, mesenchymal, endothelial, and other stromal cells. This results in chemokines playing multifaceted roles in facilitating context-dependent intercellular communications. Recent research has started to shed light on these ligands and receptors in a cancer-specific context, including cell-type specificity and drug targetability. In this review, we summarize the latest research with regards to chemokines in facilitating communication between different cell types in the tumor microenvironment.

Mesenchymal stem cells: ideal seeds for treating diseases

Mesenchymal stem cells (MSCs), a kind of multipotent stem cells with self-renewal ability and multi-differentiation ability, have become the “practical stem cells” for the treatment of diseases. MSCs have immunomodulatory properties and can be used to treat autoimmune diseases, such as systemic lupus erythematosus (SLE) and Crohn’s disease. MSCs also can be used in cancer and aging. At present, many clinical experiments are using MSCs. MSCs can reduce the occurrence of inflammation and apoptosis of tissue cells, and promote the proliferation of endogenous tissue and organ cells, so as to achieve the effect of repairing tissue and organs. MSCs presumably also play an important role in Corona Virus Disease 2019 (COVID-19) infection.

Deciphering the effects of PYCR1 on cell function and its associated mechanism in hepatocellular carcinoma

Overexpression of pyrroline-5-carboxylate reductase 1 (PYCR1) has been associated with the development of certain cancers; however, no studies have specifically examined the role of PYCR1 in hepatocellular carcinoma (HCC). Based on The Cancer Genome Atlas expression array and meta-analysis conducted using the Gene Expression Omnibus database, we determined that PYCR1 was upregulated in HCC compared to adjacent nontumor tissues (P < 0.05). These data were verified using quantitative real-time polymerase chain reaction, western blotting, and immunohistochemistry analysis. Additionally, patients with low PYCR1 expression showed a higher overall survival rate than patients with high PYCR1 expression. Furthermore, PYCR1 overexpression was associated with the female sex, higher levels of alpha-fetoprotein, advanced clinical stages (III and IV), and a younger age (< 45 years old). Silencing of PYCR1 inhibited cell proliferation, invasive migration, epithelial-mesenchymal transition, and metastatic properties in HCC in vitro and in vivo. Using RNA sequencing and bioinformatics tools for data-dependent network analysis, we found binary relationships among PYCR1 and its interacting proteins in defined pathway modules. These findings indicated that PYCR1 played a multifunctional role in coordinating a variety of biological pathways involved in cell communication, cell proliferation and growth, cell migration, a mitogen-activated protein kinase cascade, ion binding, etc. The structural characteristics of key pathway components and PYCR1-interacting proteins were evaluated by molecular docking, and hotspot analysis showed that better affinities between PYCR1 and its interacting molecules were associated with the presence of arginine in the binding site. Finally, a candidate regulatory microRNA, miR-2355-5p, for PYCR1 mRNA was discovered in HCC. Overall, our study suggests that PYCR1 plays a vital role in HCC pathogenesis and may potentially serve as a molecular target for HCC treatment.

Retinoic Acid Inhibits Tumor-Associated Mesenchymal Stromal Cell Transformation in Melanoma

Bone marrow mesenchymal stem/stromal cells (BMSCs) can be transformed into tumor-associated MSCs (TA-MSCs) within the tumor microenvironment to facilitate tumor progression. However, the underline mechanism and potential therapeutic strategy remain unclear. Here, we explored that interleukin 17 (IL-17) cooperating with IFNγ transforms BMSCs into TA-MSCs, which promotes tumor progression by recruiting macrophages/monocytes and myeloid-derived suppressor cells (MDSCs) in murine melanoma. IL-17 and IFNγ transformed TA-MSCs have high expression levels of myelocyte-recruiting chemokines (CCL2, CCL5, CCL7, and CCL20) mediated by activated NF-κB signaling pathway. Furthermore, retinoic acid inhibits NF-κB signaling, decreases chemokine expression, and suppresses the tumor-promoting function of transformed TA-MSCs by prohibiting the recruitment of macrophages/monocytes and MDSCs in the tumor microenvironment. Overall, our findings demonstrate that IL-17 collaborating with IFNγ to induce TA-MSC transformation, which can be targeted by RA for melanoma treatment.

Identification of a 5-Gene-Based Scoring System by WGCNA and LASSO to Predict Prognosis for Rectal Cancer Patients

Background

Although accumulating evidence suggested that a molecular signature panel may be more effective for the prognosis prediction than routine clinical characteristics, current studies mainly focused on colorectal or colon cancers. No reports specifically focused on the signature panel for rectal cancers (RC). Our present study was aimed at developing a novel prognostic signature panel for RC.

Methods

Sequencing (or microarray) data and clinicopathological details of patients with RC were retrieved from The Cancer Genome Atlas (TCGA-READ) or the Gene Expression Omnibus (GSE123390, GSE56699) database. A weighted gene coexpression network was used to identify RC-related modules. The least absolute shrinkage and selection operator analysis was performed to screen the prognostic signature panel. The prognostic performance of the risk score was evaluated by survival curve analyses. Functions of prognostic genes were predicted based on the interaction proteins and the correlation with tumor-infiltrating immune cells. The Human Protein Atlas (HPA) tool was utilized to validate the protein expression levels.

Results

A total of 247 differentially expressed genes (DEGs) were commonly identified using TCGA and GSE123390 datasets. Brown and yellow modules (including 77 DEGs) were identified to be preserved for RC. Five DEGs (ASB2, GPR15, PRPH, RNASE7, and TCL1A) in these two modules constituted the optimal prognosis signature panel. Kaplan-Meier curve analysis showed that patients in the high-risk group had a poorer prognosis than those in the low-risk group. Receiver operating characteristic (ROC) curve analysis demonstrated that this risk score had high predictive accuracy for unfavorable prognosis, with the area under the ROC curve of 0.915 and 0.827 for TCGA and GSE56699 datasets, respectively. This five-mRNA classifier was an independent prognostic factor. Its predictive accuracy was also higher than all clinical factor models. A prognostic nomogram was developed by integrating the risk score and clinical factors, which showed the highest prognostic power. ASB2, PRPH, and GPR15/TCL1A were predicted to function by interacting with CASQ2/PDK4/EPHA67, PTN, and CXCL12, respectively. TCL1A and GPR15 influenced the infiltration levels of B cells and dendritic cells, while the expression of PRPH was positively associated with the abundance of macrophages. HPA analysis supported the downregulation of PRPH, RNASE7, CASQ2, EPHA6, and PDK4 in RC compared with normal controls.

Conclusion

Our immune-related signature panel may be a promising prognostic indicator for RC.

Progression of prostate carcinoma is promoted by adipose stromal cell-secreted CXCL12 signaling in prostate epithelium

Aggressiveness of carcinomas is linked with tumor recruitment of adipose stromal cells (ASC), which is increased in obesity. ASC promote cancer through molecular pathways not fully understood. Here, we demonstrate that epithelial-mesenchymal transition (EMT) in prostate tumors is promoted by obesity and suppressed upon pharmacological ASC depletion in HiMyc mice, a spontaneous genetic model of prostate cancer. CXCL12 expression in tumors was associated with ASC recruitment and localized to stromal cells expressing platelet-derived growth factor receptors Pdgfra and Pdgfrb. The role of this chemokine secreted by stromal cells in cancer progression was further investigated by using tissue-specific knockout models. ASC deletion of CXCL12 gene in the Pdgfr + lineages suppressed tumor growth and EMT, indicating stroma as the key source of CXCL12. Clinical sample analysis revealed that CXCL12 expression by peritumoral adipose stroma is increased in obesity, and that the correlating increase in Pdgfr/CXCL12 expression in the tumor is linked with decreased survival of patients with prostate carcinoma. Our study establishes ASC as the source of CXCL12 driving tumor aggressiveness and outlines an approach to treatment of carcinoma progression.

Lung cancer-associated mesenchymal stem cells promote tumor metastasis and tumorigenesis by induction of epithelial-mesenchymal transition and stem-like reprogram

Mesenchymal stem cells (MSCs) have attracted more attention in antitumor therapy by using MSCs as vehicles or targeting modulators of MSCs. But their role and mechanisms in tumor progression are less known. In the present study, we successfully isolated pairs of MSCs from lung cancer (LC-MSCs) and adjacent tumor-free tissues. Based on the coculture system in vitro and animal studies in vivo, we originally found that LC-MSCs significantly promoted tumor metastasis and tumorigenesis both in vitro and in vivo. Partial epithelial–mesenchymal transition (EMT) was induced in lung cancer cells by LC-MSCs by the evidence of remarkable increase in snail and slug expression but not in other EMT-associated genes. The expression of stem related genes also escalated significantly. And spheroids perfectly formed when tumor cells were co-incubated with LC-MSCs. These results revealed a close link of partial EMT and acquisition of stem-like traits in lung cancer cells which was induced by LC-MSCs and greatly promoted metastasis and tumorigenesis in lung cancer. Our findings provided a new insight into LC-MSCs in tumor progression and helped to identify LC-MSCs as a potential vehicle or target for lung cancer therapy.

The biological role of the CXCL12/CXCR4 axis in esophageal squamous cell carcinoma

Esophageal cancer is the eighth most common malignant tumor and the sixth leading cause of cancer-related death worldwide. Esophageal squamous cell carcinoma (ESCC) is the main histological type of esophageal cancer, and accounts for 90% of all cancer cases. Despite the progress made in surgery, chemotherapy, and radiotherapy, the mortality rate from esophageal cancer remains high, and the overall 5-year survival rate is less than 20%, even in developed countries. The C-X-C motif chemokine ligand 12 (CXCL12) is a member of the CXC chemokine subgroup, which is widely expressed in a variety of tissues and cells. CXCL12 participates in the regulation of many physiological and pathological processes by binding to its specific receptor, C-X-C motif chemokine receptor type 4 (CXCR4), where it causes embryonic development, immune response, and angiogenesis. In addition, increasing evidence indicates that the CXCL12/CXCR4 axis plays an important role in the biological processes of tumor cells. Studies have shown that CXCL12 and its receptor, CXCR4, are highly expressed in ESCC. This abnormal expression contributes to tumor proliferation, lymph node and distant metastases, and worsening prognosis. At present, antagonists and imaging agents against CXCL12 or CXCR4 have been developed to interfere with the malignant process and monitor metastasis of tumors. This article summarizes the structure, function, and regulatory mechanism of CXCL12/CXCR4 and its role in the malignancy of ESCC. Current results from preclinical research targeting CXCL12/CXCR4 are also summarized to provide a reference for the clinical diagnosis and treatment of ESCC.

The Role of BRCA1/2-Mutated Tumor Microenvironment in Breast Cancer

Taking into account the factors of high incidence rate, prevalence and mortality, breast cancer represents a crucial social and economic burden. Most cases of breast cancer develop as a consequence of somatic mutations accumulating in mammary epithelial cells throughout lifetime and approximately 5-10% can be ascribed to monogenic predispositions. Even though the role of genetic predispositions in breast cancer is well described in the context of genetics, very little is known about the role of the microenvironment carrying the same aberrant cells impaired by the germline mutation in the breast cancer development and progression. Based on the clinical observations, carcinomas carrying mutations in hereditary tumor-suppressor genes involved in maintaining genome integrity such as BRCA1/2 have worse prognosis and aggressive behavior. One of the mechanisms clarifying the aggressive nature of BRCA-associated tumors implies alterations within the surrounding adipose tissue itself. The objective of this review is to look at the role of BRCA1/2 mutations in the context of breast tumor microenvironment and plausible mechanisms by which it contributes to the aggressive behavior of the tumor cells.

The Metabolic Mechanisms of Breast Cancer Metastasis

Breast cancer is one of the most common malignancy among women worldwide. Metastasis is mainly responsible for treatment failure and is the cause of most breast cancer deaths. The role of metabolism in the progression and metastasis of breast cancer is gradually being emphasized. However, the regulatory mechanisms that conduce to cancer metastasis by metabolic reprogramming in breast cancer have not been expounded. Breast cancer cells exhibit different metabolic phenotypes depending on their molecular subtypes and metastatic sites. Both intrinsic factors, such as MYC amplification, PIK3CA, and TP53 mutations, and extrinsic factors, such as hypoxia, oxidative stress, and acidosis, contribute to different metabolic reprogramming phenotypes in metastatic breast cancers. Understanding the metabolic mechanisms underlying breast cancer metastasis will provide important clues to develop novel therapeutic approaches for treatment of metastatic breast cancer.

Microenvironmental Determinants of Breast Cancer Metastasis: Focus on the Crucial Interplay Between Estrogen and Insulin/Insulin-Like Growth Factor Signaling

The development and progression of the great majority of breast cancers (BCs) are mainly dependent on the biological action elicited by estrogens through the classical estrogen receptor (ER), as well as the alternate receptor named G-protein–coupled estrogen receptor (GPER). In addition to estrogens, other hormones and growth factors, including the insulin and insulin-like growth factor system (IIGFs), play a role in BC. IIGFs cooperates with estrogen signaling to generate a multilevel cross-communication that ultimately facilitates the transition toward aggressive and life-threatening BC phenotypes. In this regard, the majority of BC deaths are correlated with the formation of metastatic lesions at distant sites. A thorough scrutiny of the biological and biochemical events orchestrating metastasis formation and dissemination has shown that virtually all cell types within the tumor microenvironment work closely with BC cells to seed cancerous units at distant sites. By establishing an intricate scheme of paracrine interactions that lead to the expression of genes involved in metastasis initiation, progression, and virulence, the cross-talk between BC cells and the surrounding microenvironmental components does dictate tumor fate and patients’ prognosis. Following (i) a description of the main microenvironmental events prompting BC metastases and (ii) a concise overview of estrogen and the IIGFs signaling and their major regulatory functions in BC, here we provide a comprehensive analysis of the most recent findings on the role of these transduction pathways toward metastatic dissemination. In particular, we focused our attention on the main microenvironmental targets of the estrogen-IIGFs interplay, and we recapitulated relevant molecular nodes that orientate shared biological responses fostering the metastatic program. On the basis of available studies, we propose that a functional cross-talk between estrogens and IIGFs, by affecting the BC microenvironment, may contribute to the metastatic process and may be regarded as a novel target for combination therapies aimed at preventing the metastatic evolution.

Tumour dormancy in inflammatory microenvironment: A promising therapeutic strategy for cancer-related bone metastasis

Cancer metastasis is a unique feature of malignant tumours. Even bone can become a common colonization site due to the tendency of solid tumours, including breast cancer (BCa) and prostate cancer (PCa), to metastasize to bone. Currently, a previous concept in tumour metabolism called tumour dormancy may be a promising target for antitumour treatment. When disseminated tumour cells (DTCs) metastasize to the bone microenvironment, they form a flexible regulatory network called the "bone-tumour-inflammation network". In this network, bone turnover as well as metabolism, tumour progression, angiogenesis and inflammatory responses are highly unified and coordinated, and a slight shift in this balance can result in the disruption of the microenvironment, uncontrolled inflammatory responses and excessive tumour growth. The purpose of this review is to highlight the regulatory effect of the "bone-tumour-inflammation network" in tumour dormancy. Osteoblast-secreted factors, bone turnover and macrophages are emphasized and occupy in the main part of the review. In addition, the prospective clinical application of tumour dormancy is also discussed, which shows the direction of future research.

The Signaling Duo CXCL12 and CXCR4: Chemokine Fuel for Breast Cancer Tumorigenesis

Simple Summary

Breast cancer remains the most common malignancy in women. In this review, we explore the role of the CXCL12/CXCR4 pathway in breast cancer. We show that the CXCL12/CXCR4 cascade is involved in nearly every aspect of breast cancer tumorigenesis including proliferation, cell motility and distant metastasis. Moreover, we summarize current knowledge about the CXCL12/CXCR4-targeted therapies. Due to the critical roles of this pathway in breast cancer and other malignancies, we believe that audiences in different fields will find this overview helpful.

Abstract

The CXCL12/CXCR4 signaling pathway has emerged in the recent years as a key player in breast cancer tumorigenesis. This pathway controls many aspects of breast cancer development including cancer cell proliferation, motility and metastasis to all target organs. Moreover, the CXCL12/CXCR4 cascade affects both immune and stromal cells, creating tumor-supporting microenvironment. In this review, we examine state-of-the-art knowledge about detrimental roles of the CXCL12/CXCR4 signaling, discuss its therapeutic potential and suggest further research directions beneficial both for basic research and personalized medicine in breast cancer.

Chemokines in bone-metastatic breast cancer: Therapeutic opportunities

Due to non-response to chemotherapy, incomplete surgical resection, and resistance to checkpoint inhibitors, breast cancer with bone metastasis is notoriously difficult to cure. Therefore, the development of novel, efficient strategies to tackle bone metastasis of breast cancer is urgently needed. Chemokines, which induce directed migration of immune cells and act as guide molecules between diverse cells and tissues, are small proteins indispensable in immunity. These complex chemokine networks play pro-tumor roles or anti-tumor roles when produced by breast cancer cells in the tumor microenvironment. Additionally, chemokines have diverse roles when secreted by various immune cells in the tumor microenvironment of breast cancer, which can be roughly divided into immunosuppressive effects and immunostimulatory effects. Recently, targeting chemokine networks has been shown to have potential for use in treatment of metastatic malignancies, including bone-metastatic breast cancer. In this review, we focus on the role of chemokines networks in the biology of breast cancer and metastasis to the bone. We also discuss the therapeutic opportunities and future prospects of targeting chemokine networks, in combination with other current standard therapies, for the treatment of bone-metastatic breast cancer.

Identification of Unique mRNA and miRNA Expression Patterns in Bone Marrow Hematopoietic Stem and Progenitor Cells After Trauma in Older Adults

Older adults have significantly worse morbidity and mortality after severe trauma than younger cohorts. The competency of the innate immune response decreases with advancing age, especially after an inflammatory insult. Subsequent poor outcomes after trauma are caused in part by dysfunctional leukocytes derived from the host's hematopoietic stem and progenitor cells (HSPCs). Our objective was to analyze the bone marrow (BM) HSPC transcriptomic [mRNA and microRNA (miR)] responses to trauma in older and younger adults. BM was collected intraoperatively <9 days after initial injury from trauma patients with non-mild injury [ISS ≥ 9] or with shock (lactate ≥ 2, base deficit ≥ 5, MAP ≤ 65) who underwent operative fixation of a pelvic or long bone fracture. Samples were also analyzed based on age (<55 years and ≥55 years), ISS score and transfusion in the first 24 h, and compared to age/sex-matched controls from non-cancer elective hip replacement or purchased healthy younger adult human BM aspirates. mRNA and miR expression patterns were calculated from lineage-negative enriched HSPCs. 924 genes were differentially expressed in older trauma subjects vs. age/sex-matched controls, while 654 genes were differentially expressed in younger subjects vs. age/sex-matched control. Only 68 transcriptomic changes were shared between the two groups. Subsequent analysis revealed upregulation of transcriptomic pathways related to quantity, function, differentiation, and proliferation of HSPCs in only the younger cohort. miR expression differences were also identified, many of which were associated with cell cycle regulation. In summary, differences in the BM HSPC mRNA and miR expression were identified between older and younger adult trauma subjects. These differences in gene and miR expression were related to pathways involved in HSPC production and differentiation. These differences could potentially explain why older adult patients have a suboptimal hematopoietic response to trauma. Although immunomodulation of HSPCs may be a necessary consideration to promote host protective immunity after host injury, the age related differences further highlight that patients may require an age-defined medical approach with interventions that are specific to their transcriptomic and biologic response. Also, targeting the older adult miRs may be possible for interventions in this patient population.

Beyond Cell Motility: The Expanding Roles of Chemokines and Their Receptors in Malignancy

The anti-tumor activities of some members of the chemokine family are often overcome by the functions of many chemokines that are strongly and causatively linked with increased tumor progression. Being key leukocyte attractants, chemokines promote the presence of inflammatory pro-tumor myeloid cells and immune-suppressive cells in tumors and metastases. In parallel, chemokines elevate additional pro-cancerous processes that depend on cell motility: endothelial cell migration (angiogenesis), recruitment of mesenchymal stem cells (MSCs) and site-specific metastasis. However, the array of chemokine activities in cancer expands beyond such “typical” migration-related processes and includes chemokine-induced/mediated atypical functions that do not activate directly motility processes; these non-conventional chemokine functions provide the tumor cells with new sets of detrimental tools. Within this scope, this review article addresses the roles of chemokines and their receptors at atypical levels that are exerted on the cancer cell themselves: promoting tumor cell proliferation and survival; controlling tumor cell senescence; enriching tumors with cancer stem cells; inducing metastasis-related functions such as epithelial-to-mesenchymal transition (EMT) and elevated expression of matrix metalloproteinases (MMPs); and promoting resistance to chemotherapy and to endocrine therapy. The review also describes atypical effects of chemokines at the tumor microenvironment: their ability to up-regulate/stabilize the expression of inhibitory immune checkpoints and to reduce the efficacy of their blockade; to induce bone remodeling and elevate osteoclastogenesis/bone resorption; and to mediate tumor-stromal interactions that promote cancer progression. To illustrate this expanding array of atypical chemokine activities at the cancer setting, the review focuses on major metastasis-promoting inflammatory chemokines—including CXCL8 (IL-8), CCL2 (MCP-1), and CCL5 (RANTES)—and their receptors. In addition, non-conventional activities of CXCL12 which is a key regulator of tumor progression, and its CXCR4 receptor are described, alongside with the other CXCL12-binding receptor CXCR7 (RDC1). CXCR7, a member of the subgroup of atypical chemokine receptors (ACKRs) known also as ACKR3, opens the gate for discussion of atypical activities of additional ACKRs in cancer: ACKR1 (DARC, Duffy), ACKR2 (D6), and ACKR4 (CCRL1). The mechanisms involved in chemokine activities and the signals delivered by their receptors are described, and the clinical implications of these findings are discussed.

The IAP Antagonist SM-164 Eliminates Triple-Negative Breast Cancer Metastasis to Bone and Lung in Mice

The most challenging issue for breast cancer (BC) patients is metastasis to other organs because current therapies do not prevent or eliminate metastatic BC. Here, we show that SM-164, a small molecule inhibitor, which degrades inhibitor of apoptosis proteins (IAPs), eliminated early-stage metastases and reduced progression of advanced BC metastasis from MDA-MB-231 BC cells in bones and lungs of nude mice. Mechanistically, SM-164-induced BC cell death is TNFα-dependent, with TNFα produced by IL-4-polarized macrophages triggering MDA-MB-231 cell apoptosis in combination with SM-164. SM-164 also inhibited expression of RANKL, which mediates interactions between metastatic BC and host microenvironment cells and induces osteoclast-mediated osteolysis. SM-164 did not kill adriamycin-resistant BC cells, while adriamycin inhibited SM-164-resistant BC cell growth, similar to parental cells. We conclude that SM-164 is a promising therapeutic agent for early stage bone and lung metastasis from triple-negative breast cancer that should be given prior to conventional chemotherapy.

Chemokines and chemokine receptors: A new strategy for breast cancer therapy

Chemokines and chemokine receptors not only participate in the development of tissue differentiation, hematopoiesis, inflammation, and immune regulation but also play an important role in the process of tumor development. The role of chemokines and chemokine receptors in tumors has been emphasized in recent years. More and more studies have shown that chemokines and chemokine receptors are closely related to the occurrence, angiogenesis, metastasis, drug resistance, and immunity of breast cancer. Here, we review recent progression on the roles of chemokines and chemokine receptors in breast cancer, and discuss the possible mechanism in breast cancer that might facilitate the development of new therapies by targeting chemokines as well as chemokine receptors. Chemokines and chemokine receptors play an important role in the occurrence and development of breast cancer. In-depth study of chemokines and chemokine receptors can provide intervention targets for breast cancer biotherapy. The regulation of chemokines and chemokine receptors may become a new strategy for breast cancer therapy.

CXCL12/CXCR4 axis in the microenvironment of solid tumors: A critical mediator of metastasis

Tumors are dynamic tissue masses, so requiring continuous exposure to the host cells, nurturing them into pave a path for tumor growth and metastasis. C-X-C chemokine ligand 12 (CXCL12)/C-X-C chemokine receptor type 4 (CXCR4) is the key signaling for such aim. Gathering knowledge about the activity within this axis would deepen our insight into the utmost importance this signaling taken to attract and cross-connect multiple cells within the tumor microenvironment (TME) aiming for tumor progression and metastasis. The concept behind this review is to underscore the multi-tasking roles taken by CXCL12/CXCR4 signaling in tumor metastasis, and to also suggest some strategies to target the activities within this axis.

The diverse and complex roles of atypical chemokine receptors in cancer: From molecular biology to clinical relevance and therapy

Chemokines regulate directed cell migration, proliferation and survival and are key components in cancer biology. They exert their functions by interacting with seven-transmembrane domain receptors that signal through G proteins (GPCRs). A subgroup of four chemokine receptors known as the atypical chemokine receptors (ACKRs) has emerged as essential regulators of the chemokine functions. ACKRs play diverse and complex roles in tumor biology from tumor initiation to metastasis, including cancer cell proliferation, adherence to endothelium, epithelial-mesenchymal transition (EMT), extravasation from blood vessels, tumor-associated angiogenesis or protection from immunological responses. This chapter gives an overview on the established and emerging roles that the atypical chemokine receptors ACKR1, ACKR2, ACKR3 and ACKR4 play in the different phases of cancer development and dissemination, their clinical relevance, as well as on the hurdles to overcome in ACKRs targeting as cancer therapy.

Transcriptome of 17β-hydroxysteroid dehydrogenase type 2 plays both hormone-dependent and hormone-independent roles in MCF-7 breast cancer cells

Breast cancer is a major cause of cancer-related death for women in western countries. 17β-Hydroxysteroid dehydrogenases (17β-HSDs) play important roles in the last step of sex-hormone activation and the first step of sex-hormone inactivation. 17β-HSD2 is responsible for oxidizing the sex hormones. We used microarray technology to analyze the effect of 17β-HSD2 on the MCF-7 cell transcript profile after knocking down 17β-HSD2. Five hundred forty-two genes were regulated 1.5-fold or higher after treatment with 17β-HSD2 siRNA. Knocking down 17β-HSD2 interrupted nucleosome assembly. Pathway-Act-Network analysis showed that the MAPK and apoptosis signaling pathways were most regulated. In the gene-gene interaction network analysis, UGT2B15, which is involved in hormone metabolism, was the most regulated core gene. FOS, GREB1, and CXCL12 were the most regulated genes, and CXCL12 was related to tumor migration. Following 17β-HSD2 knock-down, the cell viability decreased to 75.9%. The S-phase percentage decreased by 19.4%, the Q2-phase percentage in cell apoptosis testing increased by 1.5 times, and cell migration decreased to 66.0%. These results were consistent with our gene chip analysis and indicated that 17β-HSD2 plays both hormone-dependent and hormone-independent enzymatic roles. In-depth investigations of this enzyme on the genomic level will help clarify its related molecular mechanisms.

Similarities Between Stem Cell Niches in Glioblastoma and Bone Marrow: Rays of Hope for Novel Treatment Strategies

Glioblastoma is the most aggressive primary brain tumor. Slowly dividing and therapy-resistant glioblastoma stem cells (GSCs) reside in protective peri-arteriolar niches and are held responsible for glioblastoma recurrence. Recently, we showed similarities between GSC niches and hematopoietic stem cell (HSC) niches in bone marrow. Acute myeloid leukemia (AML) cells hijack HSC niches and are transformed into therapy-resistant leukemic stem cells (LSCs). Current clinical trials are focussed on removal of LSCs out of HSC niches to differentiate and to become sensitized to chemotherapy. In the present study, we elaborated further on these similarities by immunohistochemical analyses of 17 biomarkers in paraffin sections of human glioblastoma and human bone marrow. We found all 17 biomarkers to be expressed both in hypoxic peri-arteriolar HSC niches in bone marrow and hypoxic peri-arteriolar GSC niches in glioblastoma. Our findings implicate that GSC niches are being formed in glioblastoma as a copy of HSC niches in bone marrow. These similarities between HSC niches and GSC niches provide a theoretic basis for the development of novel strategies to force GSCs out of their niches, in a similar manner as in AML, to induce GSC differentiation and proliferation to render them more sensitive to anti-glioblastoma therapies.

Microenvironmental Regulation of Long Noncoding RNA LINC01133 Promotes Cancer Stem Cell-Like Phenotypic Traits in Triple-Negative Breast Cancers

The fibrotic tumor microenvironment is a critical player in the pathogenesis of triple-negative breast cancers (TNBCs), with the presence of fibroblastic infiltrates particularly correlating with tumors that are clinically advanced. On this front, we previously demonstrated that TNBCs are highly enriched in fibroblastic stromal progenitor cells called mesenchymal stem/stromal cells (MSCs) and that such cells play critical roles in promoting TNBC initiation and progression. How TNBC cells respond to MSC stimulation, however, is not fully understood, and stands to reveal contextual signals used by TNBC cells during tumor development and provide biomarkers and therapeutic targets of pertinence to TNBC management. Here, we report that MSCs strongly induced the long noncoding RNA (lncRNA) LINC01133 in neighboring TNBC cells. Indeed, although lncRNAs have been tightly associated with cancer development, their contributions to breast cancer in general, and to TNBC pathogenesis in particular, have not been fully elucidated, and we set out to determine if LINC01133 regulated malignant traits in TNBC cells. We establish that LINC01133 is sufficient, on its own, in promoting phenotypic and growth characteristics of cancer stem cell-like cells, and that it is a direct mediator of the MSC-triggered miR-199a-FOXP2 pathway in TNBC models. Furthermore, we show that LINC01133 is a critical regulator of the pluripotency-determining gene Kruppel-Like Factor 4 (KLF4), and that it represents a biomarker and prognosticator of disease outcome in the clinic. Collectively, our findings introduce LINC01133 as a novel functional driver of malignancy and a potential theranostic in TNBC. Stem Cells 2019;37:1281-1292.

CXCR7 Reactivates ERK Signaling to Promote Resistance to EGFR Kinase Inhibitors in NSCLC

Although EGFR mutant-selective tyrosine kinase inhibitors (TKI) are clinically effective, acquired resistance can occur by reactivating ERK. We show using in vitro models of acquired EGFR TKI resistance with a mesenchymal phenotype that CXCR7, an atypical G protein-coupled receptor, activates the MAPK-ERK pathway via β-arrestin. Depletion of CXCR7 inhibited the MAPK pathway, significantly attenuated EGFR TKI resistance, and resulted in mesenchymal-to-epithelial transition. CXCR7 overexpression was essential in reactivation of ERK1/2 for the generation of EGFR TKI-resistant persister cells. Many patients with non-small cell lung cancer (NSCLC) harboring an EGFR kinase domain mutation, who progressed on EGFR inhibitors, demonstrated increased CXCR7 expression. These data suggest that CXCR7 inhibition could considerably delay and prevent the emergence of acquired EGFR TKI resistance in EGFR-mutant NSCLC. SIGNIFICANCE: Increased expression of the chemokine receptor CXCR7 constitutes a mechanism of resistance to EGFR TKI in patients with non-small cell lung cancer through reactivation of ERK signaling.