Transition into inflammatory cancer-associated adipocytes in breast cancer microenvironment requires microRNA regulatory mechanism

Non-coding RNAs mediated inflammation in breast cancers

Breast cancer is the major cancer that affects women all over the world. The awareness over past several decades has led to intensive screening and detection as well as successful treatments. Still, the breast cancer mortality is unacceptable and needs to be urgently addressed. Among many factors, inflammation has often been associated with tumorigenesis, including breast cancer. More than a third of all breast cancer deaths are marked by deregulated inflammation. The exact mechanisms are still not completely known but among the many putative factors, the epigenetic changes, particularly those mediated by non-coding RNAs are fascinating. microRNAs, long non-coding RNAs as well as circular RNAs seem to impact the inflammation in breast cancer which further highlights their important regulatory role in breast cancer pathogenesis. Understanding inflammation in breast cancer and its regulation by non-coding RNAs is the primary objective of this review article. We attempt to provide the most complete information on the topic in hopes of opening new areas of research and discoveries.

Delivery of SIRT1 by cancer-associated adipocyte-derived extracellular vesicles regulates immune response and tumorigenesis of ovarian cancer cells

PURPOSE

This study intends to investigate the possible molecular mechanism of immune response and tumorigenesis in ovarian cancer cells, mediated by sirtuin 1 (SIRT1)-containing extracellular vesicles (EVs) derived from cancer-associated adipocytes (CAAs) (CAA-EVs).

METHODS

Differentially expressed genes in EVs from CAAs were screened by RNA transcriptome sequencing, and the downstream pathway was predicted in silico. The binding between SIRT1 and CD24 was investigated by luciferase activity and ChIP-PCR assays. EVs were extracted from human ovarian cancer tissue-isolated CAAs, and the internalization of CCA-EVs by ovarian cancer cells was characterized. The ovarian cancer cell line was injected into mice to establish an animal model. Flow cytometry was performed to analyze the proportions of M1 and M2 macrophages, CD8+ T, T-reg, and CD4+ T cells. TUNEL staining was used to detect cell apoptosis in the mouse tumor tissues. ELISA detection was performed on immune-related factors in the serum of mice.

RESULTS

CAA-EVs could deliver SIRT1 to ovarian cancer cells, thereby affecting the immune response of ovarian cancer cells in vitro and promoting tumorigenesis in vivo. SIRT1 could transcriptionally activate the expression of CD24, and CD24 could up-regulate Siglec-10 expression. CAA-EVs-SIRT1 activated the CD24/Siglec-10 axis and promoted CD8+ T cell apoptosis, thereby promoting tumorigenesis in mice.

CONCLUSION

CAA-EVs-mediated transfer of SIRT1 regulates the CD24/Siglec-10 axis to curb immune response and promote tumorigenesis of ovarian cancer cells.

p53 deficient breast cancer cells reprogram preadipocytes toward tumor-protective immunomodulatory cells

The TP53 gene is mutated in approximately 30% of all breast cancer cases. Adipocytes and preadipocytes, which constitute a substantial fraction of the stroma of normal mammary tissue and breast tumors, undergo transcriptional, metabolic, and phenotypic reprogramming during breast cancer development and play an important role in tumor progression. We report here that p53 loss in breast cancer cells facilitates the reprogramming of preadipocytes, inducing them to acquire a unique transcriptional and metabolic program that combines impaired adipocytic differentiation with augmented cytokine expression. This, in turn, promotes the establishment of an inflammatory tumor microenvironment, including increased abundance of Ly6C+ and Ly6G+ myeloid cells and elevated expression of the immune checkpoint ligand PD-L1. We also describe a potential gain-of-function effect of common p53 missense mutations on the inflammatory reprogramming of preadipocytes. Altogether, our study implicates p53 deregulation in breast cancer cells as a driver of tumor-supportive adipose tissue reprogramming, expanding the network of non-cell autonomous mechanisms whereby p53 dysfunction may promote cancer. Further elucidation of the interplay between p53 and adipocytes within the tumor microenvironment may suggest effective therapeutic targets for the treatment of breast cancer patients.

CAA-derived IL-6 induced M2 macrophage polarization by activating STAT3

BACKGROUND

Tumor-associated macrophages (TAMs) are the most abundant types of immune cells in the tumor microenvironment (TME) of breast cancer (BC). TAMs usually exhibit an M2 phenotype and promote tumor progression by facilitating immunosuppression. This study aimed to investigate the effect of CAA-derived IL-6 on macrophage polarization in promoting BC progression.

METHODS

Human BC samples and adipocytes co-cultured with 4T1 BC cells were employed to explore the properties of CAAs. The co-implantation of adipocytes and 4T1 cells in mouse tumor-bearing model and tail vein pulmonary metastasis model were constructed to investigate the impact of CAAs on BC malignant progression in vivo. The functional assays, qRT-PCR, western blotting assay and ELISA assay were employed to explore the effect of CAA-derived IL-6 on macrophage polarization and programmed cell death protein ligand 1 (PD-L1) expression.

RESULTS

CAAs were located at the invasive front of BC and possessed a de-differentiated fibroblast phenotype. CAAs facilitated the malignant behaviors of 4T1 cells in vitro, and promoted 4T1 tumor growth and pulmonary metastasis in vivo. The IHC staining of both human BC specimens and xenograft and the in vitro experiment indicated that CAAs could enhance infiltration of M2 macrophages in the TME of 4T1 BC. Furthermore, CAA-educated macrophages could enhance malignant behaviors of 4T1 cells in vitro. More importantly, CAAs could secret abundant IL-6 and thus induce M2 macrophage polarization by activating STAT3. In addition, CAAs could upregulate PD-L1 expression in macrophages.

CONCLUSIONS

Our study revealed that CAAs and CAA-educated macrophages enhanced the malignant behaviors of BC. Specifically, CAA-derived IL-6 induced migration and M2 polarization of macrophages via activation STAT3 and promoted macrophage PD-L1 expression, thereby leading to BC progression.

The dynamic tumor-stromal crosstalk: implications of 'stromal-hot' tumors in the process of epithelial-mesenchymal transition in breast cancer

BACKGROUND

Breast cancer metastatic programming involves an intricate process by which the tumor cell coevolves with the surrounding extracellular niche. The supporting cells from the local host stroma get transformed into cancer-associated stromal cells. This complex crosstalk leads to extracellular matrix remodeling, invasion, and eventually distant metastasis.

METHODS

In this review, we examine the protein-miRNA secretome that is crucial for this crosstalk. We also provide evidence from the literature for the pivotal role played by the various stromal cells like fibroblasts, adipocytes, and immune cells in promoting the process of EMT in breast cancer. Through in-silico analysis, we have also attempted to establish that stromal presence is integral to the process of EMT.

RESULTS AND CONCLUSION

The in-silico analysis delineates the persuasive role of the stroma in mediating epithelial-to-mesenchymal transition. This review elucidates the importance of examining the role of the stromal niche that can yield promising diagnostic markers and pave avenues for formulating tailored anti-cancer therapy. Process of EMT as driven by 'stroma-hot' tumors: The process of EMT is driven by the stromal cells. The stromal cells in the form of  fibroblasts, adipocytes, endothelial cells, mesenchymal stromal cells and tissue associated macrophages secrete the miRNA-protein secretome that modulates the stromal niche and the tumor cells to be become 'tumor associated'. This drives tumor progression and invasion. The 'stromal-hot' tumors eventually get the benefit of the surplus nurturing from the stroma that facilitates EMT leading to distant organ seeding and metastasis.

Insights into the Relationship between Pentraxin-3 and Cancer

Although cancer can be cured if detected early and treated effectively, it is still a leading cause of death worldwide. Tumor development can be limited by an appropiate immune response, but it can be promoted by chronic extensive inflammation through metabolic dysregulation and angiogenesis. In the past decade, numerous efforts have been made in order to identify novel candidates with predictive values in cancer diagnostics. In line with this, researchers have investigated the involvement of pentraxin-3 (PTX-3) in cellular proliferation and immune escape in various types of cancers, although it has not been clearly elucidated. PTX-3 is a member of the long pentraxin subfamily which plays an important role in regulating inflammation, innate immunity response, angiogenesis, and tissue remodeling. Increased synthesis of inflammatory biomarkers and activation of different cellular mechanisms can induce PTX-3 expression in various types of cells (neutrophils, monocytes, lymphocytes, myeloid dendritic cells, fibroblasts, and epithelial cells). PTX-3 has both pro- and anti-tumor functions, thus dual functions in oncogenesis. This review elucidates the potential usefulness of PTX-3 as a serum biomarker in cancer. While future investigations are needed, PTX-3 is emerging as a promising tool for cancer's diagnosis and prognosis, and also treatment monitoring.

The pleiotropic roles of adipocyte secretome in remodeling breast cancer

Background

Breast cancer is the leading female cancer type and the cause of cancer-related mortality worldwide. Adipocytes possess important functions of energy supply, metabolic regulation, and cytokine release, and are also the matrix cell that supports mammary gland tissue. In breast cancer tumor microenvironment (TME), adipocytes are the prominent stromal cells and are implicated in inflammation, metastatic formation, metabolic remodeling, and cancer susceptibility.

Main body

It is well-established that adipocyte secretome is a reservoir engaged in the regulation of tumor cell behavior by secreting a large number of cytokines (IL-6, IL-8, and chemokines), adipokines (leptin, adiponectin, autotaxin, and resistin), lipid metabolites (free fatty acids and β-hydroxybutyrate), and other exosome-encapsulated substances. These released factors influence the evolution and clinical outcome of breast cancer through complex mechanisms. The progression of breast cancer tumors revolves around the tumor-adipose stromal network, which may contribute to breast cancer aggressiveness by increasing the pro-malignant potential of TME and tumor cells themselves. Most importantly, the secretome alterations of adipocytes are regarded as distinctly important targets for breast cancer diagnosis, treatment, and drug resistance.

Conclusion

Therefore, this review will provide a comprehensive description of the specific adipocyte secretome characteristics and interactions within TME cell populations, which will enable us to better tailor strategies for tumor stratification management and treatment.

Tumor-Suppressive and Oncogenic Roles of microRNA-149-5p in Human Cancers

Malignant tumors are always a critical threat to human health, with complex pathogenesis, numerous causative factors, and poor prognosis. The features of cancers, such as gene mutations, epigenetic alterations, and the activation and inhibition of signaling pathways in the organism, play important roles in tumorigenesis and prognosis. MicroRNA (miRNA) enables the control of various molecular mechanisms and plays a variety of roles in human cancers, such as radiation sensitivity and tumor immunity, through the regulation of target genes. MiR-149-5p participates in the process and is closely related to lipogenesis, the migration of vascular endothelial cells, and the expression of stem-cell-related proteins. In recent years, its role in cancer has dramatically increased. In this review, we summarize the regular physiological roles of miRNAs, specifically miR-149-5p, in the organism and discuss the tumor-suppressive or oncogenic roles of miR-149-5p in different human cancers with respect to signaling pathways involved in regulation. Possible clinical applications of miR-149-5p in future targeted therapies and prognosis improvement in oncology are suggested.

Altered Adipokine Expression in Tumor Microenvironment Promotes Development of Triple Negative Breast Cancer

Obesity is a remarkably important factor for breast carcinogenesis and aggressiveness. The implication of increased BMI in triple negative breast cancer (TNBC) development is also well established. A malignancy-promoting role of the adipose tissue has been supposed, where the adipocytes that constitute the majority of stromal cells release pro-inflammatory cytokines and growth factors. Alterations in adipokines and their receptors play significant roles in breast cancer initiation, progression, metastasis, and drug response. Classic adipokines, such as leptin, adiponectin, and resistin, have been extensively studied in breast cancer and connected with breast cancer risk and progression. Notably, new molecules are constantly being discovered and the list is continuously growing. Additionally, substantial progress has been made concerning their differential expression in association with clinical and pathological parameters of tumors and the prognostic and predictive value of their dysregulation in breast cancer carcinogenesis. However, evidence regarding the mechanisms by which adipose tissue is involved in the development of TNBC is lacking. In the present article we comment on current data on the suggested involvement of these mediators in breast cancer development and progression, with particular emphasis on TNBC, to draw attention to the design of novel targeted therapies and biomarkers.

EGCG Prevents the Onset of an Inflammatory and Cancer-Associated Adipocyte-like Phenotype in Adipose-Derived Mesenchymal Stem/Stromal Cells in Response to the Triple-Negative Breast Cancer Secretome

Background: Triple-negative breast cancer (TNBC) cells secretome induces a pro-inflammatory microenvironment within the adipose tissue, which hosts both mature adipocytes and adipose-derived mesenchymal stem/stromal cells (ADMSC). The subsequent acquisition of a cancer-associated adipocyte (CAA)-like phenotype is, however, unknown in ADMSC. While epidemiological studies suggest that consuming a polyphenol-rich diet reduces the incidence of some obesity-related cancers, the chemopreventive impact of green tea-derived epigallocatechin-3-gallate (EGCG) against the cues that trigger the CAA phenotype remain undocumented in ADMSC. Methods: Human ADMSC were exposed to human TNBC-derived MDA-MB-231 conditioned media (TNBC cells secretome) supplemented or not with EGCG. Differential gene expression was assessed through RNA-Seq analysis and confirmed by RT-qPCR. Protein expression levels and the activation status of signal transduction pathways mediators were determined by Western blotting. ADMSC chemotaxis was assessed by a real-time cell migration assay. Results: The TNBC cells secretome induced in ADMSC the expression of the CAA cytokines CCL2, CCL5, IL-1β, and IL-6, and of immunomodulators COX2, HIF-1α, VEGFα, and PD-L1. The epithelial-to-mesenchymal biomarker Snail was found to control the CAA phenotype. EGCG inhibited the induction of CAA genes and the activation status of Smad2 and NF-κB. The induced chemotactic response was also inhibited by EGCG. Conclusion: The induction of an inflammatory and CAA-like phenotype in ADMSC can be triggered by the TNBC cells secretome, while still efficiently prevented by diet-derived polyphenols.

Multi‑faceted role of cancer‑associated adipocytes in the tumor microenvironment (Review)

Adipocytes are a type of stromal cell found in numerous different tissues that serve an active role in the tumor microenvironment. Cancer-associated adipocytes (CAAs) display a malignant phenotype and are found at the invasive tumor front, which mediates the crosstalk network between adipocytes (the precursor cells that will become cancer-associated adipocytes in the future) and cancer cells. The present review covers the mechanisms of adipocytes in the development of cancer, including metabolic reprogramming, chemotherapy resistance and adipokine regulation. Furthermore, the potential mechanisms involved in the adipocyte-cancer cell cycle in various types of cancer, including breast, ovarian, colon and rectal cancer, are discussed. Deciphering the complex network of CAA-cancer cell crosstalk will provide insights into tumor biology and optimize therapeutic strategies.

MiR-149-5p: An Important miRNA Regulated by Competing Endogenous RNAs in Diverse Human Cancers

MicroRNAs (miRNAs) consist of a large family of small, non-coding RNAs with the ability to result in gene silencing post-transcriptionally. With recent advances in research technology over the past several years, the physiological and pathological potentials of miRNAs have been gradually uncovered. MiR-149-5p, a conserved miRNA, was found to regulate physiological processes, such as inflammatory response, adipogenesis and cell proliferation. Notably, increasing studies indicate miR-149-5p may act as an important regulator in solid tumors, especially cancers in reproductive system and digestive system. It has been acknowledged that miR-149-5p can function as an oncogene or tumor suppressor in different cancers, which is achieved by controlling a variety of genes expression and adjusting downstream signaling pathway. Moreover, the levels of miR-149-5p are influenced by several newly discovered long non-coding RNAs (lncRNAs) and circular RNAs (circRNAs). However, there is blank about systematic function and mechanism of miR-149-5p in human cancers. In this review, we firstly summarize the present comprehension of miR-149-5p at the molecular level, its vital role in tumor initiation and progression, as well as its potential roles in monitoring diverse reproductive and digestive malignancies.

Overview of the molecular mechanisms contributing to the formation of cancer‑associated adipocytes (Review)

Adipocytes are the main stromal cells in the tumor microenvironment. In addition to serving as energy stores for triglycerides, adipocytes may function as an active endocrine organ. The crosstalk between adipocytes and cancer cells was shown to promote the migration, invasion and proliferation of cancer cells and to cause phenotypic and functional changes in adipocytes. Tumor-derived soluble factors, such as TNF-α, plasminogen activator inhibitor 1, Wnt3a, IL-6, and exosomal microRNAs (miRNA/miRs), including miR-144, miR-126, miR-155, as well as other miRNAs, have been shown to act on adipocytes at the tumor invasion front, resulting in the formation of cancer-associated adipocytes (CAAs) with diminished reduced terminal differentiation markers and a dedifferentiated phenotype. In addition, the number and size of CAA lipid droplets have been found to be significantly reduced compared with those of mature adipocytes, whereas inflammatory cytokines and proteases are overexpressed. The aim of the present review was to summarize the latest findings on the biological changes of CAAs and the potential role of tumor-adipocyte crosstalk in the formation of CAAs, in the hope of providing novel perspectives for breast cancer treatment.

Breast Cancer Drug Resistance: Overcoming the Challenge by Capitalizing on MicroRNA and Tumor Microenvironment Interplay

The clinical management of breast cancer reaches new frontiers every day. However, the number of drug resistant cases is still high, and, currently, this constitutes one of the major challenges that cancer research has to face. For instance, 50% of women affected with HER2 positive breast cancer presents or acquires resistance to trastuzumab. Moreover, for patients affected with triple negative breast cancer, standard chemotherapy is still the fist-line therapy, and often patients become resistant to treatments. Tumor microenvironment plays a crucial role in this context. Indeed, cancer-associated stromal cells deliver oncogenic cues to the tumor and vice versa to escape exogenous insults. It is well known that microRNAs are among the molecules exploited in this aberrant crosstalk. Indeed, microRNAs play a crucial function both in the induction of pro-tumoral traits in stromal cells and in the stroma-mediated fueling of tumor aggressiveness. Here, we summarize the most recent literature regarding the involvement of miRNAs in the crosstalk between tumor and stromal cells and their capability to modulate tumor microenvironment characteristics. All up-to-date findings suggest that microRNAs in the TME could serve both to reverse malignant phenotype of stromal cells, modulating response to therapy, and as predictive/prognostic biomarkers.

Exosomal MicroRNAs Mediating Crosstalk Between Cancer Cells With Cancer-Associated Fibroblasts and Tumor-Associated Macrophages in the Tumor Microenvironment

Exosomes are small extracellular vesicles containing diverse bioactive molecules. They play essential roles in mediating bidirectional interplay between cancer and stromal cells. Specific elements are selected into different types of exosomes via various mechanisms, including microRNAs (miRNAs), a subset of non-coding RNA that could epigenetically reprogram cells and modulate their activities. Cancer-associated fibroblasts (CAFs) and tumor-associated macrophages (TAMs) are two major types of stromal cells inhibiting immune response and facilitating tumor progression. Notably, accumulated studies provided critical evidence regarding the significance of exosomal miRNA–mediated intercellular crosstalk between cancer cells with TAMs and CAFs for tumor progression. This review aimed to summarize the current knowledge of cell–cell interactions between stromal and cancer cells conveyed by exosome-derived miRNAs. The findings might help find effective therapeutic targets of cancer.

Novel insights into the interaction between long non-coding RNAs and microRNAs in glioma

Glioma is the most common brain tumor of the central nervous system. Long non-coding RNAs (lncRNAs) and microRNAs (miRNAs) have been identified to play a vital role in the initiation and progression of glioma, including tumor cell proliferation, survival, apoptosis, invasion, and therapy resistance. New documents emerged, which indicated that the interaction between long non-coding RNAs and miRNAs contributes to the tumorigenesis and pathogenesis of glioma. LncRNAs can act as competing for endogenous RNA (ceRNA), and molecular sponge/deregulator in regulating miRNAs. These interactions stimulate different molecular signaling pathways in glioma, including the lncRNAs/miRNAs/Wnt/β-catenin molecular signaling pathway, the lncRNAs/miRNAs/PI3K/AKT/mTOR molecular signaling pathway, the lncRNAs-miRNAs/MAPK kinase molecular signaling pathway, and the lncRNAs/miRNAs/NF-κB molecular signaling pathway. In this paper, the basic roles and molecular interactions of the lncRNAs and miRNAs pathway glioma were summarized to better understand the pathogenesis and tumorigenesis of glioma.

S100A8/A9 mediate the reprograming of normal mammary epithelial cells induced by dynamic cell-cell interactions with adjacent breast cancer cells

To understand the potential effects of cancer cells on surrounding normal mammary epithelial cells, we performed direct co-culture of non-tumorigenic mammary epithelial MCF10A cells and various breast cancer cells. Firstly, we observed dynamic cell-cell interactions between the MCF10A cells and breast cancer cells including lamellipodia or nanotube-like contacts and transfer of extracellular vesicles. Co-cultured MCF10A cells exhibited features of epithelial-mesenchymal transition, and showed increased capacity of cell proliferation, migration, colony formation, and 3-dimensional sphere formation. Direct co-culture showed most distinct phenotype changes in MCF10A cells followed by conditioned media treatment and indirect co-culture. Transcriptome analysis and phosphor-protein array suggested that several cancer-related pathways are significantly dysregulated in MCF10A cells after the direct co-culture with breast cancer cells. S100A8 and S100A9 showed distinct up-regulation in the co-cultured MCF10A cells and their microenvironmental upregulation was also observed in the orthotropic xenograft of syngeneic mouse mammary tumors. When S100A8/A9 overexpression was induced in MCF10A cells, the cells showed phenotypic features of directly co-cultured MCF10A cells in terms of in vitro cell behaviors and signaling activities suggesting a S100A8/A9-mediated transition program in non-tumorigenic epithelial cells. This study suggests the possibility of dynamic cell-cell interactions between non-tumorigenic mammary epithelial cells and breast cancer cells that could lead to a substantial transition in molecular and functional characteristics of mammary epithelial cells.

FTY720 Improves the Survival of Autologous Fat Grafting by Modulating Macrophages Toward M2 Polarization Via STAT3 Pathway

Autologous fat grafting (AFG) is widely regarded as an important method for breast reconstruction after mastectomy among breast cancer (BC) patients. FTY720 has been proved to affect macrophage polarization and improve the sensitivity of postoperative BC treatment. This study aimed to explore FTY720 function and underlying mechanism in fat transplantation. The C57BL/6 J mice that received AFG were randomly divided into two groups treated with saline and FTY720, respectively. The fat graft samples were obtained at week 1, 2, 4, and 12 post-transplantation. Graft volumes, graft structures, M2 macrophages, and STAT3 protein expression were estimated by histological examination, immunofluorescence, flow cytometry, and western blot, respectively. In vitro, mouse preadipocytes were stimulated with FTY720 treated-M2 macrophages conditioned medium (FTY720-M2-CM) to evaluate the adipogenesis effect. The level of adipogenic mRNA expression in preadipocytes was detected by RT-PCR. The in vivo results showed that FTY720 treatment significantly enhanced the fat graft retention, structure integrity, and neovascularization, indicating the potential of FTY720 in improving graft survival. The histology results showed more polarized M2 macrophage presented in the FTY720 group. In the in vitro assay, after FTY720-M2-CM treatment, the 3T3-L1 preadipocytes showed the increased triglyceride content and adipogenic mRNA expression, including FABP4, C/EBP-α, Adipoq, and PPARγ. Furthermore, FTY720 treatment up-regulated the expression level of M2 biomarker CD206, Arg-1, Fizz-1, which could be weakened by the STAT3 inhibitor. Together, this study confirmed the potential efficacy of FTY720 in improving graft survival in the AFG model, possibly mediated by polarizing macrophages to M2 type through activating the STAT3 pathway.

Natural and Synthetic PPARγ Ligands in Tumor Microenvironment: A New Potential Strategy against Breast Cancer

Multiple lines of evidence indicate that activation of the peroxisome proliferator-activated receptor γ (PPARγ) by natural or synthetic ligands exerts tumor suppressive effects in different types of cancer, including breast carcinoma. Over the past decades a new picture of breast cancer as a complex disease consisting of neoplastic epithelial cells and surrounding stroma named the tumor microenvironment (TME) has emerged. Indeed, TME is now recognized as a pivotal element for breast cancer development and progression. Novel strategies targeting both epithelial and stromal components are under development or undergoing clinical trials. In this context, the aim of the present review is to summarize PPARγ activity in breast TME focusing on the role of this receptor on both epithelial/stromal cells and extracellular matrix components of the breast cancer microenvironment. The information provided from the in vitro and in vivo research indicates PPARγ ligands as potential agents with regards to the battle against breast cancer.

Verification of the role of exosomal microRNA in colorectal tumorigenesis using human colorectal cancer cell lines

Exosomes are a group of small membranous vesicles that are shed into the extracellular environment by tumoral or non-tumoral cells and contribute to cellular communication by delivering micro RNAs (miRNAs). In this study, we aimed to evaluate the role of exosomal miRNAs from colorectal cancer cell lines in tumorigenesis, by affecting cancer-associated fibroblasts (CAFs), which are vital constituents of the tumor microenvironment. To analyze the effect of exosomal miRNA on the tumor microenvironment, migration of the monocytic cell line THP-1 was evaluated via Transwell migration assay using CAFs isolated from colon cancer patients. The migration assay was performed with CAFs ± CCL7-blocking antibody and CAFs that were treated with exosomes isolated from colon cancer cell lines. To identify the associated exosomal miRNAs, miRNA sequencing and quantitative reverse transcription polymerase chain reaction were performed. The migration assay revealed that THP-1 migration was decreased in CCL7-blocking antibody-expressing and exosome-treated CAFs. Colon cancer cell lines contained miRNA let-7d in secreted exosomes targeting the chemokine CCL7. Exosomes from colorectal cancer cell lines affected CCL7 secretion from CAFs, possibly via the miRNA let-7d, and interfered with the migration of CCR2+ monocytic THP-1 cells in vitro.

Human adipocyte differentiation and composition of disease-relevant lipids are regulated by miR-221-3p

MicroRNA-221-3p (miR-221-3p) is associated with both metabolic diseases and cancers. However, its role in terminal adipocyte differentiation and lipid metabolism are uncharacterized. miR-221-3p or its inhibitor was transfected into differentiating or mature human adipocytes. Triglyceride (TG) content and adipogenic gene expression were monitored, global lipidome analysis was carried out, and mechanisms underlying the effects of miR-221-3p were investigated. Finally, cross-talk between miR-221-3p expressing adipocytes and MCF-7 breast carcinoma (BC) cells was studied, and miR-221-3p expression in tumor-proximal adipose biopsies from BC patients analyzed. miR-221-3p overexpression inhibited terminal differentiation of adipocytes, as judged from reduced TG storage and gene expression of the adipogenic markers SCD1, GLUT4, FAS, DGAT1/2, AP2, ATGL and AdipoQ, whereas the miR-221-3p inhibitor increased TG storage. Knockdown of the predicted miR-221-3p target, 14-3-3γ, had similar antiadipogenic effects as miR-221-3p overexpression, indicating it as a potential mediator of mir-221-3p function. Importantly, miR-221-3p overexpression inhibited de novo lipogenesis but increased the concentrations of ceramides and sphingomyelins, while reducing diacylglycerols, concomitant with suppression of sphingomyelin phosphodiesterase, ATP citrate lyase, and acid ceramidase. miR-221-3p expression was elevated in tumor proximal adipose tissue from patients with invasive BC. Conditioned medium of miR-221-3p overexpressing adipocytes stimulated the invasion and proliferation of BC cells, while medium of the BC cells enhanced miR-221-3p expression in adipocytes. Elevated miR-221-3p impairs adipocyte lipid storage and differentiation, and modifies their ceramide, sphingomyelin, and diacylglycerol content. These alterations are relevant for metabolic diseases but may also affect cancer progression.

Cancer-associated adipocytes: emerging supporters in breast cancer

Breast cancer (BC) is a malignant breast tumor confronted with high invasion, metastasis and recurrence rate, and adipocytes are the largest components in breast tissue. The aberrant adipocytes, especially the BC-neighbored cancer-associated adipocytes (CAAs), are found in the invasive front of BC. CAAs present a vicious phenotype compared with mature mammary adipocytes and mediate the crosstalk network between adipocytes and BC cells. By releasing multiple adipokines such as leptin, adiponectin, interleukin (IL)-6, chemokine ligand 2 (CCL2) and chemokine ligand 5 (CCL5), CAAs play essential roles in favor of proliferation, angiogenesis, dissemination, invasion and metastasis of BC. This article reviews the recent existing CAAs studies on the functions and mechanisms of adipocytes in the development of BC, including adipokine regulating, metabolic reprogramming, extracellular matrix (ECM) remodeling, microRNAs (miRNAs) and immune cell adjusting. Besides, adipocyte secretome and cellular interactions are implicated in the intervention to BC therapy and autologous fat grafting of breast reconstruction. Therefore, the potential functions and mechanisms of CAAs are very important for unveiling BC oncogenesis and progress. Deciphering the complex network between CAAs and BC is critical for designing therapeutic strategies and achieving the maximum therapeutic effects of BC.

Role of exosomes in malignant glioma: microRNAs and proteins in pathogenesis and diagnosis

Malignant gliomas are the most common and deadly type of central nervous system tumors. Despite some advances in treatment, the mean survival time remains only about 1.25 years. Even after surgery, radiotherapy and chemotherapy, gliomas still have a poor prognosis. Exosomes are the most common type of extracellular vesicles with a size range of 30 to 100 nm, and can act as carriers of proteins, RNAs, and other bioactive molecules. Exosomes play a key role in tumorigenesis and resistance to chemotherapy or radiation. Recent evidence has shown that exosomal microRNAs (miRNAs) can be detected in the extracellular microenvironment, and can also be transferred from cell to cell via exosome secretion and uptake. Therefore, many recent studies have focused on exosomal miRNAs as important cellular regulators in various physiological and pathological conditions. A variety of exosomal miRNAs have been implicated in the initiation and progression of gliomas, by activating and/or inhibiting different signaling pathways. Exosomal miRNAs could be used as therapeutic agents to modulate different biological processes in gliomas. Exosomal miRNAs derived from mesenchymal stem cells could also be used for glioma treatment. The present review summarizes the exosomal miRNAs that have been implicated in the pathogenesis, diagnosis and treatment of gliomas. Moreover, exosomal proteins could also be involved in glioma pathogenesis. Exosomal miRNAs and proteins could also serve as non-invasive biomarkers for prognosis and disease monitoring. Video Abstract.

The Multifaceted Nature of Tumor Microenvironment in Breast Carcinomas

Heterogeneity in breast carcinomas can be appreciated at various levels, from morphology to molecular alterations, and there are well-known genotypic-phenotypic correlations. Clinical decision-making is strictly focused on the evaluation of tumor cells and is based on the assessment of hormone receptors and of the HER2 status, by means of a combination of immunohistochemical and in situ hybridization techniques. The tumor microenvironment (TME) also shows a multifaceted nature stemming from the different actors populating the intratumoral and the peritumoral stroma of breast carcinomas. Of note, we have now evidence that tumor-infiltrating lymphocytes (TILs) are clinically meaningful as their quantification in the intratumoral stroma strongly correlates with good prognosis, in particular in triple-negative and HER2-positive breast cancer patients. Nevertheless, TILs are just one of the many actors orchestrating the complexity of the TME, which is populated by immune and non-immune cells (cancer-associated fibroblasts, cancer-associated adipocytes), as well as non-cellular components such as chemical inflammation mediators. In this review article we will overview the main features of the distinct cell compartments by discussing (i) the potential impact the TME may have on the prognostic stratification of breast cancers and (ii) the possible predictive value of some markers in the context of immunotherapy in light of the recent results of phase III studies in advanced and early triple-negative breast cancer patients.

Adipose Tumor Microenvironment

The term "adipose tissue" represents a multicellular and multifunctional organ involved in lipid storage, in hormone and temperature regulation, and in the protection of bones and vital organs from impact-based damage. Emerging evidence now suggests a more malignant role of adipose tissue in promoting cancer onset and progression via the release of secreted factors such as interleukin-6 (IL6) and extracellular vesicles (EVs). These adipose-source factors subsequently affect various aspects of tumorigenesis and/or cancer progression by either directly enhancing the tumor cell oncogenic phenotype or indirectly by the stimulating adjacent normal cells to adopt a more pro-cancer phenotype. Due to the recent growing interest in the role of IL6 and EVs released by adipose tissue in cancer promotion and progression, we are focusing on the protumorigenic impact of fat tissue via IL6 and EV secretion.

Bone Marrow Stromal Cells-Induced Drug Resistance in Multiple Myeloma

Multiple myeloma is a B-cell lineage cancer in which neoplastic plasma cells expand in the bone marrow and pathophysiological interactions with components of microenvironment influence many biological aspects of the malignant phenotype, including apoptosis, survival, proliferation, and invasion. Despite the therapeutic progress achieved in the last two decades with the introduction of a more effective and safe new class of drugs (i.e., immunomodulators, proteasome inhibitors, monoclonal antibodies), there is improvement in patient survival, and multiple myeloma (MM) remains a non-curable disease. The bone marrow microenvironment is a complex structure composed of cells, extracellular matrix (ECM) proteins, and cytokines, in which tumor plasma cells home and expand. The role of the bone marrow (BM) microenvironment is fundamental during MM disease progression because modification induced by tumor plasma cells is crucial for composing a "permissive" environment that supports MM plasma cells proliferation, migration, survival, and drug resistance. The "activated phenotype" of the microenvironment of multiple myeloma is functional to plasma cell proliferation and spreading and to plasma cell drug resistance. Plasma cell drug resistance induced by bone marrow stromal cells is mediated by stress-managing pathways, autophagy, transcriptional rewiring, and non-coding RNAs dysregulation. These processes represent novel targets for the ever-increasing anti-MM therapeutic armamentarium.

The plasma peptides of breast versus ovarian cancer

Background

There is a need to demonstrate a proof of principle that proteomics has the capacity to analyze plasma from breast cancer versus other diseases and controls in a multisite clinical trial design. The peptides or proteins that show a high observation frequency, and/or precursor intensity, specific to breast cancer plasma might be discovered by comparison to other diseases and matched controls. The endogenous tryptic peptides of breast cancer plasma were compared to ovarian cancer, female normal, sepsis, heart attack, Alzheimer's and multiple sclerosis along with the institution-matched normal and control samples collected directly onto ice.

Methods

Endogenous tryptic peptides were extracted from individual breast cancer and control EDTA plasma samples in a step gradient of acetonitrile, and collected over preparative C18 for LC-ESI-MS/MS with a set of LTQ XL linear quadrupole ion traps working together in parallel to randomly and independently sample clinical populations. The MS/MS spectra were fit to fully tryptic peptides or phosphopeptides within proteins using the X!TANDEM algorithm. The protein observation frequency was counted using the SEQUEST algorithm after selecting the single best charge state and peptide sequence for each MS/MS spectra. The observation frequency was subsequently tested by Chi Square analysis. The log₁₀ precursor intensity was compared by ANOVA in the R statistical system.

Results

Peptides and/or phosphopeptides of common plasma proteins such as APOE, C4A, C4B, C3, APOA1, APOC2, APOC4, ITIH3 and ITIH4 showed increased observation frequency and/or precursor intensity in breast cancer. Many cellular proteins also showed large changes in frequency by Chi Square (χ² > 100, p < 0.0001) in the breast cancer samples such as CPEB1, LTBP4, HIF-1A, IGHE, RAB44, NEFM, C19orf82, SLC35B1, 1D12A, C8orf34, HIF1A, OCLN, EYA1, HLA-DRB1, LARS, PTPDC1, WWC1, ZNF562, PTMA, MGAT1, NDUFA1, NOGOC, OR1E1, OR1E2, CFI, HSA12, GCSH, ELTD1, TBX15, NR2C2, FLJ00045, PDLIM1, GALNT9, ASH2L, PPFIBP1, LRRC4B, SLCO3A1, BHMT2, CS, FAM188B2, LGALS7, SAT2, SFRS8, SLC22A12, WNT9B, SLC2A4, ZNF101, WT1, CCDC47, ERLIN1, SPFH1, EID2, THOC1, DDX47, MREG, PTPRE, EMILIN1, DKFZp779G1236 and MAP3K8 among others. The protein gene symbols with large Chi Square values were significantly enriched in proteins that showed a complex set of previously established functional and structural relationships by STRING analysis. An increase in mean precursor intensity of peptides was observed for QSER1 as well as SLC35B1, IQCJ-SCHIP1, MREG, BHMT2, LGALS7, THOC1, ANXA4, DHDDS, SAT2, PTMA and FYCO1 among others. In contrast, the QSER1 peptide QPKVKAEPPPK was apparently specific to ovarian cancer.

Conclusion

There was striking agreement between the breast cancer plasma peptides and proteins discovered by LC-ESI-MS/MS with previous biomarkers from tumors, cells lines or body fluids by genetic or biochemical methods. The results indicate that variation in plasma peptides from breast cancer versus ovarian cancer may be directly discovered by LC-ESI-MS/MS that will be a powerful tool for clinical research. It may be possible to use a battery of sensitive and robust linear quadrupole ion traps for random and independent sampling of plasma from a multisite clinical trial.

Molecular Links between Central Obesity and Breast Cancer

Worldwide, breast cancer (BC) is the most common malignancy in women, in regard to incidence and mortality. In recent years, the negative role of obesity during BC development and progression has been made abundantly clear in several studies. However, the distribution of body fat may be more important to analyze than the overall body weight. In our review of literature, we reported some key findings regarding the role of obesity in BC development, but focused more on central adiposity. Firstly, the adipose microenvironment in obese people bears many similarities with the tumor microenvironment, in respect to associated cellular composition, chronic low-grade inflammation, and high ratio of reactive oxygen species to antioxidants. Secondly, the adipose tissue functions as an endocrine organ, which in obese people produces a high level of tumor-promoting hormones, such as leptin and estrogen, and a low level of the tumor suppressor hormone, adiponectin. As follows, in BC this leads to the activation of oncogenic signaling pathways: NFκB, JAK, STAT3, AKT. Moreover, overall obesity, but especially central obesity, promotes a systemic and local low grade chronic inflammation that further stimulates the increase of tumor-promoting oxidative stress. Lastly, there is a constant exchange of information between BC cells and adipocytes, mediated especially by extracellular vesicles, and which changes the transcription profile of both cell types to an oncogenic one with the help of regulatory non-coding RNAs.

Characterization of triple-negative breast cancer preclinical models provides functional evidence of metastatic progression

Triple-negative breast cancer (TNBC), an aggressive, metastatic and recurrent breast cancer (BC) subtype, currently suffers from a lack of adequately described spontaneously metastatic preclinical models that faithfully reproduce the clinical scenario. We describe two preclinical spontaneously metastatic TNBC orthotopic murine models for the development of advanced therapeutics: an immunodeficient human MDA-MB-231-Luc model and an immunocompetent mouse 4T1 model. Furthermore, we provide a broad range of multifactorial analysis for both models that could provide relevant information for the development of new therapies and diagnostic tools. Our comparisons uncovered differential growth rates, stromal arrangements and metabolic profiles in primary tumors, and the presence of cancer-associated adipocyte infiltration in the MDA-MB-231-Luc model. Histopathological studies highlighted the more rapid metastatic spread to the lungs in the 4T1 model following a lymphatic route, while we observed both homogeneous (MDA-MB-231-Luc) and heterogeneous (4T1) metastatic spread to axillary lymph nodes. We encountered unique metabolomic signatures in each model, including crucial amino acids and cell membrane components. Hematological analysis demonstrated severe leukemoid and lymphoid reactions in the 4T1 model with the partial reestablishment of immune responses in the immunocompromised MDA-MB-231-Luc model. Additionally, we discovered β-immunoglobulinemia and increased basal levels of G-CSF correlating with a metastatic switch, with G-CSF also promoting extramedullary hematopoiesis (both models) and causing hepatosplenomegaly (4T1 model). Overall, we believe that the characterization of these preclinical models will foster the development of advanced therapeutic strategies for TNBC treatment, especially for the treatment of patients presenting both, primary tumors and metastatic spread.

Adipocytes and microRNAs Crosstalk: A Key Tile in the Mosaic of Breast Cancer Microenvironment

Breast cancer (BC) is a disease characterized by a high grade of heterogeneity. Consequently, despite the great achievements obtained in the last decades, most of the current therapeutic regimens still fail. The identification of new molecular mechanisms that will increase the knowledge of all steps of tumor initiation and growth is mandatory in finding new clinical strategies. The BC microenvironment, consisting of endothelial cells, fibroblasts, immune cells and adipocytes, plays an essential role in regulating BC development, and recently it has gained great attention in the scientific community. In particular, adipose tissue is emerging as an important target to investigate among mammary gland components. The mechanisms underlying BC progression driven by adipocytes are predominantly unexplored, especially that involving the switch from normal adipocytes to the so-called cancer-associated adipocytes (CAAs). MicroRNAs (miRNAs), a class of gene expression modulators, have emerged as the regulators of key oncogenes and tumor suppressor genes that affect multiple pathways of the tumor microenvironment and adipose tissue. This review concerns a presentation of the role of adipocytes in breast tissue, and describes the most recent discoveries about the interplay between adipocytes and miRNAs, which collaborate in the arrangement of a pro-inflammatory and cancerous microenvironment, laying the foundations for new concepts in the prevention and treatment of BC.

E0771 and 4T1 murine breast cancer cells and interleukin 6 alter gene expression patterns but do not induce browning in cultured white adipocytes

Breast cancer remains a substantial clinical problem worldwide, and cancer-associated cachexia is a condition associated with poor prognosis in this and other malignancies. Adipose tissue is involved in the development and progression of cancer-associated cachexia, but its various roles and mechanisms of action are not completely defined, especially as it relates to breast cancer. Interleukin 6 has been implicated in several mechanisms contributing to increased breast cancer tumorigenesis, as well as a net-negative energy balance and cancer-associated cachexia via adipose tissue remodeling in other models of cancer; however, its potential role in breast cancer-associated white adipose browning has not been explored. In this study, we demonstrate localized white adipose tissue browning in a spontaneous model of murine mammary cancer. We then used an in vitro murine adipocyte culture system with the E0771 and 4T1 cell lines as models of breast cancer. We demonstrate that while the E0771 and 4T1 secretomes and cross-talk with white adipocytes alter white adipocyte mRNA expression, they do not directly induce white adipocyte browning. Additionally, we show that neither exogenous administration of interleukin 6 alone or with its soluble receptor directly induce white adipocyte browning. Together, these results demonstrate that neither the E0771 or 4T1 murine breast cancer cell lines, nor interleukin 6, directly cause browning of cultured white adipocytes. This suggests that their roles in adipose tissue remodeling are more complex and indirect in nature.

Exosomes from the tumour-adipocyte interplay stimulate beige/brown differentiation and reprogram metabolism in stromal adipocytes to promote tumour progression

BACKGROUND

Emerging evidence supports the pivotal roles of adipocytes in breast cancer progression. Tumour induced beige/brown adipose tissue differentiation contributes to the hypermetabolic state of the breast cancer. However, the mediators and mechanisms remain unclear.

METHODS

Survival probabilities were estimated using the Kaplan-Meier method based on immunohistochemistry results. Biochemical studies were performed to characterize the novel interrelation between breast cancer cells and adipocytes.

RESULTS

We show that tumour-surrounding adipocytes exhibit an altered phenotype in terms of upregulated beige/brown characteristics and increased catabolism associated with an activated state characterized by the release of metabolites, including free fatty acids, pyruvate, lactate and ketone bodies. Likewise, tumour cells cocultivated with mature adipocytes exhibit metabolic adaptation and an aggressive phenotype in vitro and in vivo. Mechanistically, we show that tumour cells induce beige/brown differentiation and remodel metabolism in resident adipocytes by exosomes from the co-culture system that carry high levels of miRNA-144 and miRNA-126. miRNA-144 promotes beige/brown adipocyte characteristics by downregulating the MAP3K8/ERK1/2/PPARγ axis, and exosomal miRNA-126 remodels metabolism by disrupting IRS/Glut-4 signalling, activating the AMPK/autophagy pathway and stabilizing HIF1α expression in imminent adipocytes. In vivo inhibition of miRNA-144 or miRNA-126 decreases adipocyte-induced tumour growth.

CONCLUSIONS

These results demonstrate that by inducing beige/brown differentiation and enhancing catabolism in recipient adipocytes, exosomal miRNA-144 and miRNA-126 from the tumour-adipocyte interaction reprogram systemic energy metabolism to facilitate tumour progression.

Genome-wide analysis reveals miR-3184-5p and miR-181c-3p as a critical regulator for adipocytes-associated breast cancer

Obesity is considered as an independent risk factor for breast cancer (BCa) and plays a major role in the breast tumor microenvironment. The etiology and mechanisms by which obesity contributes to BCa development is not yet understood. Herein, we show that in vitro coculture of BCa cells with mature adipocytes (MA-BCa) increased proliferation, migration, and invasive phenotype of BCa cells. MA-BCa coculture led to increased production of proinflammatory cytokines and chemokines. To identify microRNAs (miRNAs) in BCa cells that are modulated by the presence of adipocytes, we used small RNA sequencing analysis. Sequencing data revealed that 98 miRNAs were differentially expressed in MA-BCa. Among them, miR-3184-5p and miR-181c-3p were found to be the most upregulated and downregulated miRNAs, and direct targets are FOXP4 and PPARα, respectively. In vitro functional assays using a combination of miR-3184-5p inhibitor and miR-181c-3p mimic synergistically decreased adipocytes-induced cell proliferation and invasive capacity of BCa cells. Gene Set Enrichment analysis indicated that transcription factors were highly enriched followed by protein kinases, oncogene, and protein regulators in MA-BCa. GeneGo Metacore pathway analysis uncovered "NOTCH-induced EMT pathway" was found to be the most abundant in MA-BCa. Consistently, epithelial-mesenchymal transition-associated markers were also increased in MA-BCa. The disease enrichment analysis of the predict target genes revealed that diabetes mellitus was significantly affected disease in MA-BCa. Taken together, our data suggest that miRNA-based regulatory mechanism associated with deregulation of pathways and biological functions orchestrated by adipocytes-secreted factors might drive the BCa progression and metastasis in obese patients.

Interleukin-8 Activates Breast Cancer-Associated Adipocytes and Promotes Their Angiogenesis- and Tumorigenesis-Promoting Effects

Increasing evidence supports the critical role of active stromal adipocytes in breast cancer development and spread. However, the mediators and the mechanisms of action are still elusive. We show here that cancer-associated adipocytes (CAAs) isolated from 10 invasive breast carcinomas are proinflammatory and exhibit active phenotypes, including higher proliferative, invasive, and migratory capacities compared to their adjacent tumor-counterpart adipocytes (TCAs). Furthermore, all CAAs secreted higher level of interleukin-8 (IL-8), which is critical in mediating the paracrine procarcinogenic effects of these cells. Importantly, ectopic expression of IL-8 in TCA cells activated them and enhanced their procarcinogenic effects both in vitro, in a STAT3-dependent manner, and in vivo In contrast, inhibition of the IL-8 signaling using specific short hairpin RNA, anti-IL-8 antibody, or reparixin suppressed the active features of CAAs, including their non-cell-autonomous tumor-promoting activities both on breast luminal cells and in orthotopic tumor xenografts in mice. IL-8 played also an important role in enhancing the proangiogenic effects of breast adipocytes. These results provide clear indication that IL-8 plays key roles in the activation of breast CAAs and acts as a major mediator for their paracrine protumorigenic effects. Thus, targeting CAAs by inhibiting the IL-8 pathway could have great therapeutic value.

Epigenetic Crosstalk between the Tumor Microenvironment and Ovarian Cancer Cells: A Therapeutic Road Less Traveled

Metastatic dissemination of epithelial ovarian cancer (EOC) predominantly occurs through direct cell shedding from the primary tumor into the intra-abdominal cavity that is filled with malignant ascitic effusions. Facilitated by the fluid flow, cells distribute throughout the cavity, broadly seed and invade through peritoneal lining, and resume secondary tumor growth in abdominal and pelvic organs. At all steps of this unique metastatic process, cancer cells exist within a multidimensional tumor microenvironment consisting of intraperitoneally residing cancer-reprogramed fibroblasts, adipose, immune, mesenchymal stem, mesothelial, and vascular cells that exert miscellaneous bioactive molecules into malignant ascites and contribute to EOC progression and metastasis via distinct molecular mechanisms and epigenetic dysregulation. This review outlines basic epigenetic mechanisms, including DNA methylation, histone modifications, chromatin remodeling, and non-coding RNA regulators, and summarizes current knowledge on reciprocal interactions between each participant of the EOC cellular milieu and tumor cells in the context of aberrant epigenetic crosstalk. Promising research directions and potential therapeutic strategies that may encompass epigenetic tailoring as a component of complex EOC treatment are discussed.

Exosomes of glioma cells deliver miR-148a to promote proliferation and metastasis of glioblastoma via targeting CADM1

Exosomes are now considered to be involved in mediating cell-to-cell communication to promote or inhibit tumor progression. However, the role and molecular mechanism of exosomes in promoting glioblastoma (GBM) metastasis remains elusive. Here, we found that circulating exosomal miR-148a levels were significantly higher in serum from GBM patients compared with serum from healthy volunteers. In T98G cells, inhibition of miR-148a suppressed cell proliferation and metastasis. In addition, we identified Cell adhesion molecule 1 (CADM1) as a target gene of miR-148a using luciferase reporter assay. Both protein and mRNA levels of CADM1 were decreased in tissues from GBM patients. There was a strong negative correlation between exosomal miR-148a and CADM1 mRNA levels in samples of patients. Moreover, miR-148a antagonist increased p-STAT3 protein level to activate STAT3 pathway. In conclusion, our findings indicated that miR-148a delivered by exosomes may promote cancer cell proliferation and metastasis via targeting CADM1 to activate STAT3 pathway, suggesting a predictor and therapeutic target role of exosomal miR-148a in GBM patients.

Exosomes released by hepatocarcinoma cells endow adipocytes with tumor-promoting properties

Background

The initiation and progression of hepatocellular carcinoma (HCC) are largely dependent on its local microenvironment. Adipocytes are an important component of hepatic microenvironment in nonalcoholic fatty liver disease (NAFLD), which is a significant risk factor for HCC. Given the global prevalence of NAFLD, a better understanding of the interplay between HCC cells and adipocytes is urgently needed. Exosomes, released by malignant cells, represent a novel way of cell-cell interaction and have been shown to play an important role in cancer cell communication with their microenvironment. Here, we explore the role of HCC-derived exosomes in the cellular and molecular conversion of adipocytes into tumor-promoting cells.

Methods

Exosomes were isolated from HCC cell line HepG2 and added to adipocytes. Transcriptomic alterations of exosome-stimulated adipocytes were analyzed using gene expression profiling, and secretion of inflammation-associated cytokines was detected by RT-PCR and ELISA. In vivo mouse xenograft model was used to evaluate the growth-promoting and angiogenesis-enhancing effects of exosome-treated adipocytes. Protein content of tumor exosomes was analyzed by mass spectrometry. Activated phospho-kinases involved in exosome-treated adipocytes were detected by phospho-kinase antibody array and Western blot.

Results

Our results demonstrated that HCC cell HepG2-derived exosomes could be actively internalized by adipocytes and caused significant transcriptomic alterations and in particular induced an inflammatory phenotype in adipocytes. The tumor exosome-treated adipocytes, named exo-adipocytes, promoted tumor growth, enhanced angiogenesis, and recruited more macrophages in mouse xenograft model. In vitro, conditioned medium from exo-adipocytes promoted HepG2 cell migration and increased tube formation of human umbilical vein endothelial cells (HUVECs). Mechanistically, we found HepG2 exosomes activated several phopho-kinases and NF-κB signaling pathway in exo-adipocytes. Additionally, a total of 1428 proteins were identified in HepG2 exosomes by mass spectrometry.

Conclusions

Our results provide new insights into the concept that tumor cell-derived exosomes can educate surrounding adipocytes to create a favorable microenvironment for tumor progression.

Multifaceted Roles of Interleukin-6 in Adipocyte-Breast Cancer Cell Interaction

Breast cancer is the most common malignancy in women worldwide, with a developmental process spanning decades. The malignant cells recruit a variety of cells including fibroblasts, endothelial cells, immune cells, and adipocytes, creating the tumor microenvironment. The tumor microenvironment has emerged as active participants in breast cancer progression and response to treatment through autocrine and paracrine interaction with the malignant cells. Adipose tissue is abundant in the breast cancer microenvironment; interactions with cancer cells create cancer-associated adipocytes which produce a variety of adipokines that influence breast cancer initiation, metastasis, angiogenesis, and cachexia. Interleukin (IL)-6 has emerged as key compound significantly produced by breast cancer cells and adipocytes, with the potential of inducing proliferation, epithelial-mesenchymal phenotype, stem cell phenotype, angiogenesis, cachexia, and therapeutic resistance in breast cancer cells. Our aim is to present a brief knowledge of IL-6’s role in breast cancer. This review summarizes our current understanding of the breast microenvironment, with emphasis on adipocytes as key players in breast cancer tumorigenesis. The effects of key adipocytes such as leptin, adipokines, TGF-b, and IL-6 are discussed. Finally, we discuss the role of IL-6 in various aspects of cancer progression.

Exosomal miRNAs and miRNA dysregulation in cancer-associated fibroblasts

Purpose

The present review aimed to assess the role of exosomal miRNAs in cancer-associated fibroblasts (CAFs), normal fibroblasts (NFs), and cancer cells. The roles of exosomal miRNAs and miRNA dysregulation in CAF formation and activation were summarized.

Methods

All relevant publications were retrieved from the PubMed database, with key words such as CAFs, CAF, stromal fibroblasts, cancer-associated fibroblasts, miRNA, exosomal, exosome, and similar terms.

Results

Recent studies have revealed that CAFs, NFs, and cancer cells can secrete exosomal miRNAs to affect each other. Dysregulation of miRNAs and exosomal miRNAs influence the formation and activation of CAFs. Furthermore, miRNA dysregulation in CAFs is considered to be associated with a secretory phenotype change, tumor invasion, tumor migration and metastasis, drug resistance, and poor prognosis.

Conclusions

Finding of exosomal miRNA secretion provides novel insights into communication among CAFs, NFs, and cancer cells. MicroRNA dysregulation is also involved in the whole processes of CAF formation and function. Dysregulation of miRNAs in CAFs can affect the secretory phenotype of the latter cells.