Tumor-derived osteopontin reprograms normal mammary fibroblasts to promote inflammation and tumor growth in breast cancer

An RGDKGE-Containing Cryptic Collagen Fragment Regulates Phosphorylation of Large Tumor Suppressor Kinase-1 and Controls Ovarian Tumor Growth by a Yes-Associated Protein-Dependent Mechanism

The growth and spread of malignant tumors, such as ovarian carcinomas, are governed in part by complex interconnected signaling cascades occurring between stromal and tumor cells. These reciprocal cross-talk signaling networks operating within the local tissue microenvironment may enhance malignant tumor progression. Understanding how novel bioactive molecules generated within the tumor microenvironment regulate signaling pathways in distinct cellular compartments is critical for the development of more effective treatment paradigms. Herein, we provide evidence that blocking cellular interactions with an RGDKGE-containing collagen peptide that selectively binds integrin β3 on ovarian tumor cells enhances the phosphorylation of the hippo effector kinase large tumor suppressor kinase-1 and reduces nuclear accumulation of yes-associated protein and its target gene c-Myc. Selectively targeting this RGDKGE-containing collagen fragment inhibited ovarian tumor growth and the development of ascites fluid in vivo. These findings suggest that this bioactive collagen fragment may represent a previously unknown regulator of the hippo effector kinase large tumor suppressor kinase-1 and regulate ovarian tumor growth by a yes-associated protein-dependent mechanism. Taken together, these data not only provide new mechanistic insight into how a unique collagen fragment may regulate ovarian cancer, but in addition may help provide a useful new alternative strategy to control ovarian tumor progression based on selectively disrupting a previously unappreciated signaling cascade.

Tumor-derived osteopontin drives the resident fibroblast to myofibroblast differentiation through Twist1 to promote breast cancer progression

Tumor-stroma interactions are important determinants for the disease course in cancer. While stromal influence has been known to often play a tumor-promoting role, incomplete mechanistic insight into this phenomenon has prevented its therapeutic targeting. Stromal fibroblasts can be activated by tumor cells to differentiate into cancer-associated fibroblasts (CAFs), that exhibit the traits of myofibroblasts, and in turn, they increase cancer aggressiveness. Here, we report the crosstalk between the cancer cells and stromal fibroblasts that leads to tumor progression. The process is initiated by secretion of a chemokine like protein, osteopontin (OPN) from the cancer cells that differentiates the fibroblasts to myofibroblasts. Tumor-derived OPN achieves this transition by engaging CD44 and αvβ3 integrins on the fibroblast surface, which mediates signaling via Akt and ERK to induce Twist1-dependent gene expression. The OPN-driven CAFs then secrete CXCL12, which in turn triggers epithelial to mesenchymal transition (EMT) in the tumor cells. OPN, produced by the cancer cells, and CXCL12, secreted by activated fibroblasts, are necessary and sufficient to perpetuate the crosstalk. Knocking out OPN in carcinogen-induced mammary tumors or knocking down OPN in cancer cells and fibroblast co-implanted xenografts abrogates myofibroblast differentiation, Twist1, and CXCL12 expression. OPN expression is correlated with CAF-specific gene signature as shown by breast tumor tissue microarray consisting of 100 patient specimens. Bioinformatics analyses have confirmed that the expression of OPN is significantly correlated with the expression of myofibroblast-specific markers as demonstrated in human breast carcinoma dataset of 2509 patients. Our findings describe OPN and CXCL12 act as compelling targets to curb the tumor-promoting features of the stromal components and further suggested that OPN-regulated CXCL12 network might act as potential therapeutic target for the management of CAF-mediated breast cancer progression.

Osteopontin Blockade Immunotherapy Increases Cytotoxic T Lymphocyte Lytic Activity and Suppresses Colon Tumor Progression

Simple Summary

Despite the breakthrough in human cancer immunotherapy, colorectal cancer, except for the small subset of microsatellite instable colorectal cancer (MSI, ~4% total cases), is one of the few human cancers that does not respond to current immune checkpoint inhibitor (ICI) immunotherapy. CTLs are present in both MSI and microsatellite stable (MSS) human colon carcinoma, suggesting that PD-L1-independent mechanisms may exist and suppress CTL activation in the colon tumor microenvironment. We determined that osteopontin (OPN) inhibits tumor-specific cytotoxic T lymphocyte (CTL) lytic activity to promote colon tumor growth in vivo. Accordingly, OPN blockade immunotherapy using OPN neutralization monoclonal antibodies 100D3 and 103D6 suppressed colon tumor growth in vivo. Our findings indicate that 100D3 and 103D6 has the potential to be further developed for colorectal cancer immunotherapy.

Abstract

Human colorectal cancers are mostly microsatellite-stable with no response to anti-PD-1 blockade immunotherapy, necessitating the development of a new immunotherapy. Osteopontin (OPN) is elevated in human colorectal cancer and may function as an immune checkpoint. We aimed at elucidating the mechanism of action of OPN and determining the efficacy of OPN blockade immunotherapy in suppression of colon cancer. We report here that OPN is primarily expressed in tumor cells, myeloid cells, and innate lymphoid cells in human colorectal carcinoma. Spp1 knock out mice exhibit a high incidence and fast growth rate of carcinogen-induced tumors. Knocking out Spp1 in colon tumor cells increased tumor-specific CTL cytotoxicity in vitro and resulted in decreased tumor growth in vivo. The OPN protein level is elevated in the peripheral blood of tumor-bearing mice. We developed four OPN neutralization monoclonal antibodies based on their efficacy in blocking OPN inhibition of T cell activation. OPN clones 100D3 and 103D6 increased the efficacy of tumor-specific CTLs in killing colon tumor cells in vitro and suppressed colon tumor growth in tumor-bearing mice in vivo. Our data indicate that OPN blockade immunotherapy with 100D3 and 103D6 has great potential to be further developed for colorectal cancer immunotherapy and for rendering a colorectal cancer response to anti-PD-1 immunotherapy.

Lung cancer cell-derived EDA-containing fibronectin induces an inflammatory response from monocytes and promotes metastatic tumor microenvironment

Tumor-associated macrophages (TAMs) play a pivotal role in facilitating tumor growth and metastasis. This tumor-promoting propensity of TAMs sets in as a result of their complex cross-talk with tumor cells mediated primarily by tumor cell-secreted proteins in the tumor microenvironment. To explore such interactions, we employed an immunoscreening approach involving the immunization of Balb-c mice with model human lung carcinoma cell line, A549. From serological examination combined with mass spectrometric analysis, EDA-containing fibronectin (EDA_FN ) was identified as a conspicuous immunogenic protein in A549 cell secretome. We showed that A549 secreted EDA_FN engages TLR-4 on THP-1 monocytes to drive the proinflammatory response via NF-κB signaling cascade. Conversely, A549 derived EDA_FN potentiates their metastatic capacity by inducing epithelial-mesenchymal transition through its autocrine activity. In conclusion, the study proposes a possible mechanism of cellular cross-talk between lung cancer cells and associated monocytes mediated by lung cancer-derived EDA_FN and resulting in the establishment of proinflammatory and metastatic tumor microenvironment.

Osteopontin Signaling in Shaping Tumor Microenvironment Conducive to Malignant Progression

Context-dependent reciprocal crosstalk between cancer and surrounding stromal cells in the tumor microenvironment is imperative for the regulation of various hallmarks of cancer. A myriad of growth factors, chemokines, and their receptors aids in the interaction between cancer cells and tumor microenvironmental components. Osteopontin is a chemokine-like protein, overexpressed in different types of cancers. Osteopontin plays a crucial role in orchestrating dialogue between cancer and stromal cells. Osteopontin, in tumor microenvironment, is produced in tumor as well as stromal cells. Tumor-derived osteopontin regulates proliferation, migration, activation, and differentiation of different types of stromal cells. Osteopontin secreted from tumor cells regulates the generation of cancer-associated fibroblasts from resident fibroblasts and mesenchymal stem cells. Osteopontin also shapes immunosuppressive tumor microenvironment by controlling regulatory T cells and tumor-associated macrophages. Moreover, secretion of osteopontin from tumor stroma has been highly documented. Stromal cell-derived osteopontin induces epithelial-to-mesenchymal transition, angiogenesis, metastasis, and cancer stem cell enrichment. Tumor- or stroma-derived osteopontin mainly functions through binding with cell surface receptors, integrins and CD44, and activates downstream signaling events like PI-3 kinase/Akt and MAPK pathways. Presumably, disrupting the communication between the tumor cells and surrounding microenvironment by targeting osteopontin-regulated signaling using specific antibodies, small-molecule inhibitors, and chemotherapeutic agents is a novel therapeutic strategy for clinical management of cancer.

IER2-induced senescence drives melanoma invasion through osteopontin

Expression of the immediate-early response gene IER2 has been associated with the progression of several types of cancer, but its functional role is poorly understood. We found that increased IER2 expression in human melanoma is associated with shorter overall survival, and subsequently investigated the mechanisms through which IER2 exerts this effect. In experimental melanoma models, sustained expression of IER2 induced senescence in a subset of melanoma cells in a p53/MAPK/AKT-dependent manner. The senescent cells produced a characteristic secretome that included high levels of the extracellular phosphoglycoprotein osteopontin. Nuclear localization of the IER2 protein was critical for both the induction of senescence and osteopontin secretion. Osteopontin secreted by IER2-expressing senescent cells strongly stimulated the migration and invasion of non-senescent melanoma cells. Consistently, we observed coordinate expression of IER2, p53/p21, and osteopontin in primary human melanomas and metastases, highlighting the pathophysiological relevance of IER2-mediated senescence in melanoma progression. Together, our study reveals that sustained IER2 expression drives melanoma invasion and progression through stimulating osteopontin secretion via the stochastic induction of senescence.

Osteopontin: A Key Regulator of Tumor Progression and Immunomodulation

Simple Summary

Anti-PD-1/PD-L1 and anti-CTLA-4-based immune checkpoint blockade (ICB) immunotherapy have recently emerged as a breakthrough in human cancer treatment. Durable efficacy has been achieved in many types of human cancers. However, not all human cancers respond to current ICB immunotherapy and only a fraction of the responsive cancers exhibit efficacy. Osteopontin (OPN) expression is highly elevated in human cancers and functions as a tumor promoter. Emerging data suggest that OPN may also regulate immune cell function in the tumor microenvironment. This review aims at OPN function in human cancer progression and new findings of OPN as a new immune checkpoint. We propose that OPN compensates PD-L1 function to promote tumor immune evasion, which may underlie human cancer non-response to current ICB immunotherapy.

Abstract

OPN is a multifunctional phosphoglycoprotein expressed in a wide range of cells, including osteoclasts, osteoblasts, neurons, epithelial cells, T, B, NK, NK T, myeloid, and innate lymphoid cells. OPN plays an important role in diverse biological processes and is implicated in multiple diseases such as cardiovascular, diabetes, kidney, proinflammatory, fibrosis, nephrolithiasis, wound healing, and cancer. In cancer patients, overexpressed OPN is often detected in the tumor microenvironment and elevated serum OPN level is correlated with poor prognosis. Initially identified in activated T cells and termed as early T cell activation gene, OPN links innate cells to adaptive cells in immune response to infection and cancer. Recent single cell RNA sequencing revealed that OPN is primarily expressed in tumor cells and tumor-infiltrating myeloid cells in human cancer patients. Emerging experimental data reveal a key role of OPN is tumor immune evasion through regulating macrophage polarization, recruitment, and inhibition of T cell activation in the tumor microenvironment. Therefore, in addition to its well-established direct tumor cell promotion function, OPN also acts as an immune checkpoint to negatively regulate T cell activation. The OPN protein level is highly elevated in peripheral blood of human cancer patients. OPN blockade immunotherapy with OPN neutralization monoclonal antibodies (mAbs) thus represents an attractive approach in human cancer immunotherapy.

Unfolding innate mechanisms in the cancer microenvironment: The emerging role of the mesenchyme

Innate mechanisms in the tumor stroma play a crucial role both in the initial rejection of tumors and in cancer promotion. Here, we provide a concise overview of the innate system in cancer and recent advances in the field, including the activation and functions of innate immune cells and the emerging innate properties and modulatory roles of the fibroblastic mesenchyme. Novel insights into the diverse identities and functions of the innate immune and mesenchymal cells in the microenvironment of tumors should lead to improved anticancer therapies.

Osteopontin is highly secreted in the cerebrospinal fluid of patient with posterior pituitary involvement in Langerhans cell histiocytosis

BACKGROUND

Langerhans cell histiocytosis (LCH) is a rare disease caused by clonal proliferation of CD1a⁺ CD207⁺ cells. Distinguishing pituitary involvement was essential in stratification and treatment of patients with LCH. The diagnosis of pituitary involvement is mainly dependent on hormone abnormalities in the anterior pituitary and magnetic resonance imaging (MRI) scanning in posterior pituitary. Diabetes insipidus (DI) is a serious sequelae and often occurred with pituitary involvement. It is reported that osteopontin (OPN) is highly secreted in the cerebrospinal fluid (CSF) of patients with neurodegenerative diseases in LCH (LCH-ND). However, patients with posterior pituitary involvement account for a larger portion in our hospital. Whether the OPN level could be an auxiliary diagnostic marker for the posterior pituitary involvement or not is still unknown.

METHODS

In our study, we collected CSF samples of 57 children with LCH. The secreted OPN (sOPN) levels in CSF were measured through enzyme-linked immunosorbent assay (ELISA).

RESULTS

After the retrospective analysis of 57 patients with LCH, we found that the sOPN levels in CSF of children with posterior pituitary involvement were significantly higher than that of other groups. After the Pearson Chi-Square test, Fisher's exact test and ROC analysis, we found that the sOPN levels were significantly correlated with posterior pituitary involvement. The cut-off value is 214.14 ng/mL.

CONCLUSION

The sOPN levels were elevated in CSF of LCH children with posterior pituitary involvement. Analysis of the sOPN level may provide more accurate auxiliary diagnostic techniques for the clinic.

Characterization of four subtypes in morphologically normal tissue excised proximal and distal to breast cancer

Widespread mammographic screening programs and improved self-monitoring allow for breast cancer to be detected earlier than ever before. Breast-conserving surgery is a successful treatment for select women. However, up to 40% of women develop local recurrence after surgery despite apparently tumor-free margins. This suggests that morphologically normal breast may harbor early alterations that contribute to increased risk of cancer recurrence. We conducted a comprehensive transcriptomic and proteomic analysis to characterize 57 fresh-frozen tissues from breast cancers and matched histologically normal tissues resected proximal to (<2 cm) and distant from (5-10 cm) the primary tumor, using tissues from cosmetic reduction mammoplasties as baseline. Four distinct transcriptomic subtypes are identified within matched normal tissues: metabolic; immune; matrisome/epithelial-mesenchymal transition, and non-coding enriched. Key components of the subtypes are supported by proteomic and tissue composition analyses. We find that the metabolic subtype is associated with poor prognosis (p < 0.001, HR6.1). Examination of genes representing the metabolic signature identifies several genes able to prognosticate outcome from histologically normal tissues. A subset of these have been reported for their predictive ability in cancer but, to the best of our knowledge, these have not been reported altered in matched normal tissues. This study takes an important first step toward characterizing matched normal tissues resected at pre-defined margins from the primary tumor. Unlocking the predictive potential of unexcised tissue could prove key to driving the realization of personalized medicine for breast cancer patients, allowing for more biologically-driven analyses of tissue margins than morphology alone.

Upregulation of secreted phosphoprotein 1 affects malignant progression, prognosis, and resistance to cetuximab via the KRAS/MEK pathway in head and neck cancer

Acquired resistance is a barrier to cetuximab efficacy in patients with head and neck squamous cell carcinoma (HNSCC). Secreted phosphoprotein 1 (SPP1) is involved in various biological processes, including immune responses, cancer progression, and prognosis in many cancers, while little is known in HNSCC. Bioinformatics methods were used to identify candidate genes and further in vivo and in vitro experiments were performed to examine and validate the function of SPP1. We found that SPP1 was upregulated and has been found to have an oncogenic role in HNSCC. We further confirmed that overexpression of SPP1 affected proliferation, migration, invasion, and survival, and inhibited apoptosis, whereas silencing of SPP1 yielded opposite results to those of SPP1 overexpression. In addition, activation of the KRAS/MEK pathway contributed to the SPP1-induced malignant progression of HNSCC and resistance to cetuximab. Furthermore, SPP1 knockdown or an MEK inhibitor overcame this cetuximab-resistance pattern. Taken together, our findings for the first time identify the role of SPP1 in tumor promotion, prognostic prediction, and potential therapeutic targeting, as well as resistance to cetuximab in HNSCC.

The Multifaceted Roles of MSCs in the Tumor Microenvironment: Interactions With Immune Cells and Exploitation for Therapy

The tumor microenvironment (TME) plays a critical role in tumorigenesis and is composed of different cellular components, including immune cells and mesenchymal stromal cells (MSCs). In this review, we will discuss MSCs in the TME setting and more specifically their interactions with immune cells and how they can both inhibit (immunosurveillance) and favor (immunoediting) tumor growth. We will also discuss how MSCs are used as a therapeutic strategy in cancer. Due to their unique immunomodulatory properties, MSCs isolated from perinatal tissues are intensely explored as therapeutic interventions in various inflammatory-based disorders with promising results. However, their therapeutic applications in cancer remain for the most part controversial and, importantly, the interactions between administered perinatal MSC and immune cells in the TME remain to be clearly defined.

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.

High type I collagen density fails to increase breast cancer stem cell phenotype

Breast cancer is a highly frequent and lethal malignancy which metastasis and relapse frequently associates with the existence of breast cancer stem cells (CSCs). CSCs are undifferentiated, aggressive and highly resistant to therapy, with traits modulated by microenvironmental cells and the extracellular matrix (ECM), a biologically complex and dynamic structure composed mainly by type I collagen (Col-I). Col-I enrichment in the tumor-associated ECM leads to microenvironment stiffness and higher tumor aggressiveness and metastatic potential. While Col-I is also known to induce tumor stemness, it is unknown if such effect is dependent of Col-I density. To answer this question, we evaluated the stemness phenotype of MDA-MB-231 and MCF-7 human breast cancer cells cultured within gels of varying Col-I densities. High Col-I density increased CD44⁺CD24⁻ breast cancer stem cell (BCSC) immunophenotype but failed to potentiate Col-I fiber alignment, cell self-renewal and clonogenicity in MDA-MB-231 cells. In MCF-7 cells, high Col-I density decreased total levels of variant CD44 (CD44v). Common to both cell types, high Col-I density induced neither markers related to CSC nor those related with mechanically-induced cell response. We conclude that high Col-I density per se is not sufficient to fully develop the BCSC phenotype.

Recent advances in understanding cancer-associated fibroblasts in pancreatic cancer

Pancreatic ductal adenocarcinoma (PDA) is a devastating disease with a poor survival rate. It is resistant to therapy in part due to its unique tumor microenvironment, characterized by a desmoplastic reaction resulting in a dense stroma that constitutes a large fraction of the tumor volume. A major contributor to the desmoplastic reaction are cancer-associated fibroblasts (CAFs). CAFs actively interact with cancer cells and promote tumor progression by different mechanisms, including extracellular matrix deposition, remodeling, and secretion of tumor promoting factors, making CAFs an attractive target for PDA. However, emerging evidences indicate significant tumor-suppressive functions of CAFs, highlighting the complexity of CAF biology. CAFs were once considered as a uniform cell type within the cancer stroma. Recently, the existence of CAF heterogeneity in PDA has become appreciated. Due to advances in single cell technology, distinct subtypes of CAFs have been identified in PDA. Here we review recent updates in CAF biology in PDA, which may help develop effective CAF-targeted therapies in the future.

New screening system using Twist1 promoter activity identifies dihydrorotenone as a potent drug targeting cancer-associated fibroblasts

Cancer-associated fibroblasts (CAFs) are the most abundant stromal cells in tumor microenvironments. These cells strongly support tumor progression and are considered to be potent therapeutic targets. Therefore, drugs targeting CAFs have been developed, but most of them have failed in clinical trials. The discovery of additional drugs to inactivate or eliminate CAFs is thus essential. In this study, we developed a high-throughput screening system to find anti-CAF drugs using reporter cells that express Twist1 promoter-GFP. This screening system uses the activity of the Twist1 promoter as an indicator of CAF activation because Twist1 is known to be a central player in CAF activation. Using this screening system, we found that dihydrorotenone (DHR), an inhibitor of electron transfer chain complex 1 in mitochondria, can effectively deactivate CAFs. DHR-treated CAFs exhibited reduced expression of CAF-enriched markers, decreased capability of collagen gel contraction, and impaired ability to engage in tumor-promoting activities, such as facilitating the proliferation and colonization of cancer cells. Furthermore, conditioned media from DHR-treated CAFs attenuated tumor progression in mice grafted with MNK28 cells. In conclusion, DHR can be considered as a candidate drug targeting CAFs.

Crosstalk Between Prostate Cancer Cells and Tumor-Associated Fibroblasts Enhances the Malignancy by Inhibiting the Tumor Suppressor PLZF

Although prostate cancer is clinically manageable during the early stages of progression, metastatic progression severely compromises the prognosis and leads to mortality. Constitutive activation of STAT3 has been connected to prostate cancer malignancy, and abolishing the STAT3 activity may diminish tumor growth and metastasis. However, its suppressor genes and pathways have not been well established. In this study, we show that promyelocytic leukemia zinc finger (PLZF) has a putative tumor-suppressor function in prostate cancer by inhibiting phosphorylation of STAT3. Compared with a benign prostate, high-grade prostate cancer patient tissue was negatively correlated with PLZF expression. PLZF depletion accelerated proliferation and survival, migration, and invasion in human prostate cancer cells. Mechanistically, we demonstrated a novel role of PLZF as the transcriptional regulator of the tyrosine phosphatase SHP-1 that inhibits the oncogenic JAKs–STAT3 pathway. These results suggest that the collapse of PLZF expression by the CCL3 derived from fibroblasts accelerates the cell migration and invasion properties of prostate cancer cells. Our results suggest that increasing PLZF could be an attractive strategy for suppressing prostate cancer metastasis as well as for tumor growth.

TRAF6 Activates Fibroblasts to Cancer-Associated Fibroblasts through FGF19 in Tumor Microenvironment to Benefit the Malignant Phenotype of Melanoma Cells

Cancer-associated fibroblasts (CAFs) are an important component of the tumor microenvironment and mediate tumor progression in various cancers. A previous study demonstrated that TRAF6 promotes the malignant phenotype of melanoma cells. However, the role of TRAF6 in melanoma CAFs remains unclear. In this study, we found that TRAF6 was significantly upregulated in CAFs adjacent to melanoma cells. Functional assays showed that TRAF6 promoted fibroblast proliferation and migration as well as MMP and α-SMA expression. Moreover, the expression of TRAF6 in fibroblasts promoted the malignant phenotype of melanoma cells in vitro and in vivo. Meanwhile, the intervention of TRAF6 expression in melanoma cells affected the activation of CAFs. We found that FGF19 was a key cytokine regulated by TRAF6 through NF-κB1 using luciferase assay and chromatin immunoprecipitation in melanoma cells. Because plasma FGF19 levels are elevated in patients with melanoma, it may significantly induce fibroblast activation in vitro and in vivo. Taken together, our results support that TRAF6 is a key molecule that mediates the interaction between melanoma cells and stromal fibroblasts, suggesting that TRAF6 is a potentially promising target in melanoma therapy.

The Matrix Revolution: Matricellular Proteins and Restructuring of the Cancer Microenvironment

The extracellular matrix (ECM) surrounding cells is indispensable for regulating their behavior. The dynamics of ECM signaling are tightly controlled throughout growth and development. During tissue remodeling, matricellular proteins (MCP) are secreted into the ECM. These factors do not serve classical structural roles, but rather regulate matrix proteins and cell-matrix interactions to influence normal cellular functions. In the tumor microenvironment, it is becoming increasingly clear that aberrantly expressed MCPs can support multiple hallmarks of carcinogenesis by interacting with various cellular components that are coupled to an array of downstream signals. Moreover, MCPs also reorganize the biomechanical properties of the ECM to accommodate metastasis and tumor colonization. This realization is stimulating new research on MCPs as reliable and accessible biomarkers in cancer, as well as effective and selective therapeutic targets.

Evaluation of SPP1/osteopontin expression as predictor of recurrence in tamoxifen treated breast cancer

Breast cancer patients treated with tamoxifen may experience recurrence due to endocrine resistance, which highlights the need for additional predictive and prognostic biomarkers. The glyco-phosphoprotein osteopontin (OPN), encoded by the SPP1 gene, has previously shown to be associated with poor prognosis in breast cancer. However, studies on the predictive value of OPN are inconclusive. In the present study, we evaluated tissue SPP1 mRNA and OPN protein expression as markers of recurrence in estrogen receptor- positive (ER+) breast cancer tissue. Tamoxifen- treated patients with recurrence or non-recurrence were selected using a matched case-control design. SPP1 mRNA expression was analysed using qPCR (n = 100) and OPN protein by immunohistochemistry (n = 116) using different antibodies. Odds ratios were estimated with conditional logistic regression. The SPP1 expression increased the risk of recurrence with an odds ratio (OR) of 2.50 (95% confidence interval [CI]; 1.30–4.82), after adjustment for tumour grade, HER 2 status and other treatments to OR 3.62 (95% CI; 1.45–9.07). However, OPN protein expression was not associated with risk of recurrence or with SPP1-gene expression, suggesting SPP1 mRNA a stronger prognostic marker candidate compared to tumor tissue OPN protein.

A Case-Control Study of the Association Between the SPP1 Gene SNPs and the Susceptibility to Breast Cancer in Guangxi, China

Secreted phosphoprotein-1 (SPP1) has been reported to be involved in the pathogenesis of breast cancer (BRC), but the influence of SPP1 single nucleotide polymorphisms on the BRC susceptibility has been rarely reported. In this study, we explored the association between rs11730582, rs2853750, and rs35893069 in the SPP1 gene and the BRC susceptibility. We used Snapshot assay to detect SPP1 single nucleotide polymorphisms in 471 BRC patients and 471 controls. The plasma SPP1 level was measured by ELISA. We found that the CC genotype and C allele of rs11730582 were associated with a significantly decreased BRC risk compared with the TT genotype and T allele, respectively [CC vs. TT: odds ratio (OR) = 0.59, 95% CI = 0.37–0.94, P = 0.026; C vs. T: OR = 0.79, 95% CI = 0.65–0.96, P = 0.022]. In addition, BRC patients and controls with the rs11730582 CC genotype had a lower plasma SPP1 level than did BRC patients and controls with TT genotype (P = 0.007 and P = 0.011, respectively). Moreover, the proportions of rs11730582 CC genotype and C allele were decreased in BRC patients with clinical stages I–III compared with those with clinical stage IV (P = 0.012 and P = 0.003, respectively). Besides, the C-G-T haplotype was associated with a significantly decreased BRC risk compared with the T-A-T haplotype (OR = 0.69, 95% CI = 0.52–0.93, P = 0.015). However, there was no significant association between rs2853750 or rs35893069 and the BRC risk. In summary, our study found the association between rs11730582 and the risk of BRC and suggested that rs11730582 may promote the occurrence and development of BRC by regulating SPP1 expression.

The Role of Adipokines in Breast Cancer: Current Evidence and Perspectives

PURPOSE

The current review shows evidence for the role of adipokines in breast cancer (BC) pathogenesis summarizing the mechanisms underlying the association between adipokines and breast malignancy. Special emphasis is given also on intriguing insights into the relationship between obesity and BC as well as on the role of novel adipokines in BC development.

RECENT FINDINGS

Recent evidence has underscored the role of the triad of obesity, insulin resistance, and adipokines in postmenopausal BC. Adipokines exert independent and joint effects on activation of major intracellular signal networks implicated in BC cell proliferation, growth, survival, invasion, and metastasis, particularly in the context of obesity, considered a systemic endocrine dysfunction characterized by chronic inflammation. To date, more than 10 adipokines have been linked to BC, and this catalog is continuously increasing. The majority of circulating adipokines, such as leptin, resistin, visfatin, apelin, lipocalin 2, osteopontin, and oncostatin M, is elevated in BC, while some adipokines such as adiponectin and irisin (adipo-myokine) are generally decreased in BC and considered protective against breast carcinogenesis. Further evidence from basic and translational research is necessary to delineate the ontological role of adipokines and their interplay in BC pathogenesis. More large-scale clinical and longitudinal studies are awaited to assess their clinical utility in BC prognosis and follow-up. Finally, novel more effective and safer adipokine-centered therapeutic strategies could pave the way for targeted oncotherapy.

Stromal reprogramming: A target for tumor therapy

Cancer associated fibroblasts (CAFs) as the dominant, long-lived and highly plastic cells within the tumor microenvironment (TME) with multi-faceted roles that are endowed with tumor aggressive features. They can instruct and shape the stroma of tumor into being a highly qualified bed for cellular recruitment, differentiation and plasticity in the host tissue or secondary organ/s. In this Review, we have a discussion over CAF reprogramming as a general concept, inducers and outcomes, pursued by suggesting potential strategies to combat this key promoter of tumor.

Bone morphogenetic protein 4 provides cancer-supportive phenotypes to liver fibroblasts in patients with hepatocellular carcinoma

BACKGROUND

Cancer-associated fibroblasts (CAFs) are essential constituents of cancer-supportive microenvironments. The high incidence of hepatocellular carcinoma (HCC) in advanced fibrosis patients implies that fibroblasts have a promoting effect on HCC development. We aimed to explore the regulators of phenotypes and function of CAFs in the liver.

METHODS

We established primary cancer-associated fibroblasts (CAFs) and non-cancerous liver fibroblasts (NFs) from 15 patients who underwent HCC resection. We compared phenotypes, capacity of cytokine/chemokine production and gene expression profiles between pairs of CAFs and NFs from the same donors. We examined resected tissue from additional 50 patients with HCC for immunohistochemical analyses.

RESULTS

The CAFs expressed more ACTA2 and COL1A1 than the NFs, suggesting that CAFs are more activated phenotype. The CAFs produced larger amounts of IL-6, IL-8 and CCL2 than the NFs, which led to invasiveness of HuH7 in vitro. We found that Bone Morphogenetic Protein-4 (BMP4) is up-regulated in CAFs compared to NFs. The CAF phenotype and function were gained by BMP4 over-expression or recombinant BMP4 given to fibroblasts, all of which decreased with BMP4 knockdown. In tissues obtained from the patients, BMP4-positive cells are mainly observed in encapsulated fibrous lesions and HCC. Positive expression of BMP4 in HCC in resected tissues, not in fibroblasts, was associated with poorer postoperative overall survival in patients with HCC.

CONCLUSION

Endogenous and exogenous BMP4 activate liver fibroblasts to gain capacity of secreting cytokines and enhancing invasiveness of cancer cells in the liver. BMP4 is one of the regulatory factors of CAFs functioning in the microenvironment of HCC.

miR-155 overexpression is followed by downregulation of its target gene, NFE2L2, and altered pattern of VEGFA expression in the liver of melanoma B16-bearing mice at the premetastatic stage

MicroRNAs are involved in the control of tumour progression and in metastatic cascade dynamics. However, the role of microRNAs in distant organ reorganization at the premetastatic stage is less clear, although the process of premetastatic niche formation is a crucial event according to modern concepts of tumour dissemination. The role of the present study was to investigate the expression levels of miR-155, miR-21, miR-205 and miR-let7b, as well as that of their target genes, in target organs of melanoma metastasis at the premetastatic stage. The expression levels of both the pro-oncogenic miR-155 and the tumour suppressive miR-205 were found to be altered in the premetastatic liver of melanoma B16-bearing mice. Bioinformatics analysis identified the target genes of miR-155 to be nuclear factor, erythroid 2 like 2 (NFE2L2), secretogranin II, miR-205, semaphorin 5A and vascular endothelial growth factor A (VEGFA). Among those, the redox status regulatory factor NFE2L2 was downregulated, which corresponded to increased levels of miR-155. Due to the ability of pro-oxidative events to initiate angiogenesis, VEGFA levels were evaluated in the premetastatic liver by immunohistochemistry, which revealed increased VEGFA expression in the central parts of the organ and diminished expression in the periphery. Taken together, these findings may support the concept of functional organ reorganization due to melanoma progression.

Calcitriol Analogues Decrease Lung Metastasis but Impair Bone Metabolism in Aged Ovariectomized Mice Bearing 4T1 Mammary Gland Tumours

Calcitriol and its analogues are considered drugs supporting the anticancer treatment of breast cancer and preventing the osteoporosis that results from the development of cancer or from chemotherapy or hormone therapy. Following the orthotopic implantation of 4T1 mammary carcinoma cells into aged ovariectomized (OVX) mice, we evaluated the effects of calcitriol and its two analogues, PRI-2191 and PRI-2205, on metastatic spread and bone homeostasis. Calcitriol and its analogues temporarily inhibited the formation of metastases in the lungs. Unexpectedly, only mice treated with calcitriol analogues showed a deterioration of bone-related parameters, such as bone column density, marrow column density and the CaPO₄ coefficient. These findings correlated with an increased number of active osteoclasts differentiated from bone marrow-derived macrophages in mice treated with the analogues. Interestingly, in the tumours from mice treated with PRI-2191 and PRI-2205, the expression of Tnfsf11 (RANKL) was increased. On the other hand, osteopontin (OPN) levels in plasma and tumour tissue, as well as TRAC5b levels in tumours, were diminished by calcitriol and its analogues. Despite a similar action of both analogues towards bone metabolism, their impact on vitamin D metabolism differed. In particular, PRI-2191 and calcitriol, not PRI-2205 treatment significantly diminished the levels of both 25(OH)D₃ and 24,25(OH)₂D₃. In conclusion, though there is evident antimetastatic activity in old OVX mice, signs of increased bone metabolism and deterioration of bone mineralization during therapy with calcitriol analogues were observed.

NLRP3 inflammasome in fibroblasts links tissue damage with inflammation in breast cancer progression and metastasis

Cancer-Associated Fibroblasts (CAFs) were shown to orchestrate tumour-promoting inflammation in multiple malignancies, including breast cancer. However, the molecular pathways that govern the inflammatory role of CAFs are poorly characterised. In this study we found that fibroblasts sense damage-associated molecular patterns (DAMPs), and in response activate the NLRP3 inflammasome pathway, resulting in instigation of pro-inflammatory signalling and secretion of IL-1β. This upregulation was evident in CAFs in mouse and in human breast carcinomas. Moreover, CAF-derived inflammasome signalling facilitated tumour growth and metastasis, which was attenuated when NLRP3 or IL-1β were specifically ablated. Functionally, CAF-derived inflammasome promoted tumour progression and metastasis by modulating the tumour microenvironment towards an immune suppressive milieu and by upregulating the expression of adhesion molecules on endothelial cells. Our findings elucidate a mechanism by which CAFs promote breast cancer progression and metastasis, by linking the physiological tissue damage response of fibroblasts with tumour-promoting inflammation.

Linkage of CD8+ T cell exhaustion with high-fat diet-induced tumourigenesis

Obesity increases the risk of cancer. Increased levels of hormones (such as oestrogen, insulin, insulin-like growth factor, and leptin), free fatty acid-induced production of reactive oxygen species, an altered intestinal microbiome and chronic inflammation are known to be associated with an increased cancer risk in obese subjects. However, the mechanism underlying the connection between obesity and cancer development remains elusive. Here, we show that a high-fat diet (HFD) promotes tumour initiation/progression and induces a phenotypic switch from PD-1⁻ CD8⁺non-exhausted T cells to PD-1⁺ CD8⁺exhausted T cells in a murine breast cancer model. While PD-1⁻ CD8⁺non-exhausted T cells predominated in the mammary glands of normal diet (ND)-fed mice, PD-1⁺ CD8⁺exhausted T cells accumulated in the developing tumours of HFD-fed mice. Gene expression profiles indicated that PD-1⁺ CD8⁺ T cells expressed higher levels of the tumour-trophic gene Opn and lower levels of the cytotoxic genes Ifng and Gzmb than did PD-1⁻ CD8⁺ T cells. Our study provides a possible mechanistic linkage between obesity and cancer.

The Dark Side of Fibroblasts: Cancer-Associated Fibroblasts as Mediators of Immunosuppression in the Tumor Microenvironment

Cancer-associated fibroblasts (CAFs) are prominent components of the microenvironment in most types of solid tumors, and were shown to facilitate cancer progression by supporting tumor cell growth, extracellular matrix remodeling, promoting angiogenesis, and by mediating tumor-promoting inflammation. In addition to an inflammatory microenvironment, tumors are characterized by immune evasion and an immunosuppressive milieu. In recent years, CAFs are emerging as central players in immune regulation that shapes the tumor microenvironment. CAFs contribute to immune escape of tumors via multiple mechanisms, including secretion of multiple cytokines and chemokines and reciprocal interactions that mediate the recruitment and functional differentiation of innate and adaptive immune cells. Moreover, CAFs directly abrogate the function of cytotoxic lymphocytes, thus inhibiting killing of tumor cells. In this review, we focus on recent advancements in our understanding of how CAFs drive the recruitment and functional fate of tumor-infiltrating immune cells toward an immunosuppressive microenvironment, and provide outlook on future therapeutic implications that may lead to integration of preclinical findings into the design of novel combination strategies, aimed at impairing the tumor-supportive function of CAFs.

Paracrine Crosstalk between Fibroblasts and ER+ Breast Cancer Cells Creates an IL1β-Enriched Niche that Promotes Tumor Growth

Breast cancer-induced activated fibroblasts support tumor progression. However, the role of normal fibroblasts in tumor progression remains controversial. In this study, we used modified patient-derived organoid cultures and demonstrate that constitutively secreted cytokines from normal breast fibroblasts initiate a paracrine signaling mechanism with estrogen receptor-positive (ER⁺) breast cancer cells, which results in the creation of an interleukin (IL)-1β-enriched microenvironment. We found that this paracrine signaling mechanism is shared between normal and activated fibroblasts. Interestingly, we observed that in reconstructed tumor microenvironment containing autologous ER⁺ breast cancer cells, activated fibroblasts, and immune cells, tamoxifen is more effective in reducing tumor cell proliferation when this paracrine signaling is blocked. Our findings then suggest that ER⁺ tumor cells could create a growth-promoting environment without activating stromal fibroblasts and that in breast-conserving surgeries, normal fibroblasts could be a significant modulator of tumor recurrence by enhancing the proliferation of residual breast cancer cells in the tumor-adjacent breast tissue.

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Normal fibroblast-cancer cell interaction promotes tumor progression

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Paracrine signaling common to normal and activated fibroblasts promotes drug resistance

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Fibroblast-secreted factors create an IL1β-enriched niche for ER⁺ breast cancer cell growth

Osteopontin as a multifaceted driver of bone metastasis and drug resistance

Metastasis to bone frequently occurs in majority of patients with advanced breast cancer and prostate cancer, leading to devastating skeletal-related events and substantially reducing the survival of patients. Currently, the crosstalk between tumor cells and the bone stromal compartment was widely investigated for bone metastasis and the resistance to many conventional therapeutic methods. Osteopontin (OPN), also known as SPP1 (secreted phosphoprotein 1), a secreted and chemokine-like glyco-phosphoprotein is involved in tumor progression such as cell proliferation, angiogenesis, and metastasis. The expression of OPN in tumor tissue and plasma has been clinically proved to be correlated to poor prognosis and shortened survival in patients with breast cancer and prostate cancer. This review summarizes the multifaceted roles that OPN plays in bone microenvironment and drug resistance, with emphasis on breast and prostate cancers, via binding to αvβ3 integrin and CD44 receptor and inducing signaling cascades. We further discuss the promising therapeutic strategy for OPN targeting, mainly inhibiting OPN at transcriptional or protein level or blocking it binding to receptor or its downstream signaling pathways. The comprehending of the function of OPN in bone microenvironment is crucial for the development of novel biomarker and potential therapeutic target for the diagnosis and treatment of bone metastasis and against the emergence of drug resistance in advanced cancers.

Integrin Regulation of CAF Differentiation and Function

Extensive remodeling of the extracellular matrix, together with paracrine communication between tumor cells and stromal cells, contribute to an “activated” tumor microenvironment that supports malignant growth and progression. These stromal cells include inflammatory cells, endothelial cells, and cancer-associated fibroblasts (CAFs). Integrins are expressed on all tumor and stromal cell types where they regulate both cell adhesion and bidirectional signal transduction across the cell membrane. In this capacity, integrins control pro-tumorigenic cell autonomous functions such as growth and survival, as well as paracrine crosstalk between tumor cells and stromal cells. The myofibroblast-like properties of cancer-associated fibroblasts (CAFs), such as robust contractility and extracellular matrix (ECM) deposition, allow them to generate both chemical and mechanical signals that support invasive tumor growth. In this review, we discuss the roles of integrins in regulating the ability of CAFs to generate and respond to extracellular cues in the tumor microenvironment. Since functions of specific integrins in CAFs are only beginning to emerge, we take advantage of a more extensive literature on how integrins regulate wound myofibroblast differentiation and function, as some of these integrin functions are likely to extrapolate to CAFs within the tumor microenvironment. In addition, we discuss the roles that integrins play in controlling paracrine signals that emanate from epithelial/tumor cells to stimulate fibroblasts/CAFs.

Activated Fibroblast Program Orchestrates Tumor Initiation and Progression; Molecular Mechanisms and the Associated Therapeutic Strategies

: Neoplastic epithelial cells coexist in carcinomas with various non-neoplastic stromal cells, together creating the tumor microenvironment. There is a growing interest in the cross-talk between tumor cells and stromal fibroblasts referred to as carcinoma-associated fibroblasts (CAFs), which are frequently present in human carcinomas. CAF populations extracted from different human carcinomas have been shown to possess the ability to influence the hallmarks of cancer. Indeed, several mechanisms underlying CAF-promoted tumorigenesis are elucidated. Activated fibroblasts in CAFs are characterized as alpha-smooth muscle actin-positive myofibroblasts and actin-negative fibroblasts, both of which are competent to support tumor growth and progression. There are, however, heterogeneous CAF populations presumably due to the diverse sources of their progenitors in the tumor-associated stroma. Thus, molecular markers allowing identification of bona fide CAF populations with tumor-promoting traits remain under investigation. CAFs and myofibroblasts in wound healing and fibrosis share biological properties and support epithelial cell growth, not only by remodeling the extracellular matrix, but also by producing numerous growth factors and inflammatory cytokines. Notably, accumulating evidence strongly suggests that anti-fibrosis agents suppress tumor development and progression. In this review, we highlight important tumor-promoting roles of CAFs based on their analogies with wound-derived myofibroblasts and discuss the potential therapeutic strategy targeting CAFs.

Osteopontin Promotes Colorectal Cancer Cell Invasion and the Stem Cell-Like Properties through the PI3K-AKT-GSK/3β-β/Catenin Pathway

BACKGROUND Osteopontin (OPN) is a molecule expressed in numerous cancers including colorectal cancer (CRC) that correlates disease progression. The interaction of OPN that promotes CRC cell migration, invasion, and cancer stem-like cells (CSCs) have not been elucidated. Hence, we aimed to investigate the mechanisms that might be involved. MATERIAL AND METHODS Expression of OPN in tumor tissues derived from patients was monitored with real-time quantitative polymerase chain reaction and western blot. Wound healing and Transwell assay were used to test the differences in migration and invasion in an OPN enriched environment and OPN knockdown condition. Aldehyde dehydrogenase 1 (ALDH1) positive stem cells were isolated using fluorescence-activated cell sorting (FACS) following the protocol of the ALDEFLUOR™ kit. The expression of protein participation in the PI3K-Akt-GSK/3ß-ß/catenin pathway was detected by western blot. RESULTS OPN exhibited increased levels in CRC tumor tissue compared with non-tumor normal tissue and the high level of which correlated with lymphatic metastasis and late TNM stage. Additional rhOPN co-cultured low-expression CRC cells demonstrated more aggressive capability of proliferation, migration, and invasion. For knockdown of OPN in high-expression CRC cells, the bioactivities of proliferation, migration, and invasion were significantly inhibited. Interestingly, the percentage of ALDH1 labeled stem cells was dramatically decreased by OPN inhibition. The phosphorylation of PI3K-Akt-GSK/3ß-ß/catenin pathway was involved in the OPN signaling. Furthermore, Ly294002, a specific PI3K inhibitor, can reverse the promotion of bioactivities and stem cell proportion among rhOPN treated CRC cells. CONCLUSIONS OPN promoted cell proliferation, migration, and invasion, and was accompanied by upregulation of ALDH1-positive CSC in CRC through activation of PI3K-Akt-GSK/3ß-ß/catenin pathway.

Differential MicroRNA Landscape Triggered by Estrogens in Cancer Associated Fibroblasts (CAFs) of Primary and Metastatic Breast Tumors

Cancer associated fibroblasts (CAFs) play a main role in breast cancer progression and metastasis. Estrogens modulate in breast CAFs the expression of microRNAs (miRNAs) that are involved in the development of many tumors. In order to provide novel insights on the regulation of miRNAs by estrogens in breast cancer, we analyzed the expression of 754 miRNAs in CAFs obtained from primary mammary tumors and CAFs derived from a cutaneous breast cancer metastasis. Using the TaqMan™ Human MicroRNA Array, we found that 17β-estradiol (E2) modulates numerous peculiar and common miRNAs in CAFs derived from primary and the metastatic malignancies. In particular, we assessed that E2 modulates 133 miRNAs (41 up and 92 downregulated) in CAFs derived from primary breast tumors, whereas E2 modulates 415 miRNAs (399 up and 16 downregulated) in CAFs derived from a cutaneous metastasis of breast carcinoma. Therefore, a number of miRNAs three times higher in metastatic CAFs with respect to primary breast CAFs was found modulated by E2. Our findings shed new light on the cumulative regulation of miRNAs by E2 in the main players of the tumor microenvironment as CAFs. Moreover, our data may be taken into consideration that is useful toward innovative prognostic and therapeutic approaches in breast cancer progression.

Hepatocellular carcinoma-derived exosomal miRNA-21 contributes to tumor progression by converting hepatocyte stellate cells to cancer-associated fibroblasts

BACKGROUND

Hepatocellular carcinoma (HCC) remains a global challenge due to its high morbidity and mortality rates as well as poor response to treatment. The communication between tumor-derived elements and stroma plays a critical role in facilitating cancer progression of HCC. Exosomes are small extracellular vesicles (EVs) that are released from the cells upon fusion of multivesicular bodies with the plasma membrane. There is emerging evidence indicating that exosomes play a central role in cell-to-cell communication. Much attention has been paid to exosomes since they are found to transport bioactive proteins, messenger RNA (mRNAs) and microRNA (miRNAs) that can be transferred in active form to adjacent cells or to distant organs. However, the mechanisms underlying such cancer progression remain largely unexplored.

METHODS

Exosomes were isolated by differential ultracentrifugation from conditioned medium of HCC cells and identified by electron microscopy and Western blotting analysis. Hepatic stellate cells (HSCs) were treated with different concentrations of exosomes, and the activation of HSCs was analyzed by Western blotting analysis, wound healing, migration assay, Edu assay, CCK-8 assay and flow cytometry. Moreover, the different miRNA levels of exosomes were tested by real-time quantitative PCR (RT-PCR). The angiogenic ability of activated HSCs was analyzed by qRT-PCR, CCK-8 assay and tube formation assay. In addition, the abnormal lipid metabolism of activated HSCs was analyzed by Western blotting analysis and Oil Red staining. Finally, the relationship between serum exosomal miRNA-21 and prognosis of HCC patients was evaluated.

RESULTS

We showed that HCC cells exhibited a great capacity to convert normal HSCs to cancer-associated fibroblasts (CAFs). Moreover, our data revealed that HCC cells secreted exosomal miRNA-21 that directly targeted PTEN, leading to activation of PDK1/AKT signaling in HSCs. Activated CAFs further promoted cancer progression by secreting angiogenic cytokines, including VEGF, MMP2, MMP9, bFGF and TGF-β. Clinical data indicated that high level of serum exosomal miRNA-21 was correlated with greater activation of CAFs and higher vessel density in HCC patients.

CONCLUSIONS

Intercellular crosstalk between tumor cells and HSCs was mediated by tumor-derived exosomes that controlled progression of HCC. Our findings provided potential targets for prevention and treatment of live cancer.

Bone marrow-derived fibroblasts are a functionally distinct stromal cell population in breast cancer

Raz et al. demonstrate that the expression of PDGFRα distinguishes two functional CAF populations in breast tumors and lung metastases and identify a subpopulation of CAFs that are specifically recruited to the tumor microenvironment from mesenchymal stromal cells in the BM.

Cancer-associated fibroblasts (CAFs) are highly prominent in breast tumors, but their functional heterogeneity and origin are still largely unresolved. We report that bone marrow (BM)–derived mesenchymal stromal cells (MSCs) are recruited to primary breast tumors and to lung metastases and differentiate to a distinct subpopulation of CAFs. We show that BM-derived CAFs are functionally important for tumor growth and enhance angiogenesis via up-regulation of Clusterin. Using newly generated transgenic mice and adoptive BM transplantations, we demonstrate that BM-derived fibroblasts are a substantial source of CAFs in the tumor microenvironment. Unlike resident CAFs, BM-derived CAFs do not express PDGFRα, and their recruitment resulted in a decrease in the percentage of PDGFRα-expressing CAFs. Strikingly, decrease in PDGFRα in breast cancer patients was associated with worse prognosis, suggesting that BM-derived CAFs may have deleterious effects on survival. Therefore, PDGFRα expression distinguishes two functionally unique CAF populations in breast tumors and metastases and may have important implications for patient stratification and precision therapeutics.

Osteopontin-targeted probe detects orthotopic breast cancers using optoacoustic imaging

Improved detection of breast cancer using highly sensitive, tumor-specific imaging would facilitate diagnosis, surveillance and assessment of response to treatment. We conjugated osteopontin peptide to an infrared fluorescent dye to serve as a contrast agent for detection of breast cancer by multispectral optoacoustic tomography (MSOT). Selective binding of the osteopontin-based probe was identified using flow cytometry and near infrared fluorescent imaging in triple negative and HER2 positive breast cancer cell lines in vitro. Osteopontin-750 accumulation was evaluated in vivo using MSOT with secondary confirmation of signal accumulation using near infrared fluorescent imaging. The osteopontin-based probe demonstrated binding to breast cancer cells in vitro. Similarly, after intravenous administration of the osteopontin-750 probe, it accumulated preferentially in the subcutaneous breast tumor in nude mice (557 MSOT a.u. compared to untargeted organs such as kidney (53.7 MSOT a.u.) and liver (32.1 MSOT a.u.). At 2.5 h post-injection, signal intensity within the tumor was 9.7 and 17 times greater in the tumor bed than in the kidney or liver, respectively. Fluorescence imaging ex vivo comparing tumor signal to that of nontarget organs confirmed the results in vivo. MSOT imaging demonstrated selective accumulation of the fluorescent osteopontin targeting probe to tumor sites both in vitro and in vivo, and provided high-resolution images. Further development of this tool is promising for advanced diagnostic imaging, disease surveillance and therapeutic models that limit nontarget toxicity.

Synergistic tumor microenvironment targeting and blood-brain barrier penetration via a pH-responsive dual-ligand strategy for enhanced breast cancer and brain metastasis therapy

Cancer associated fibroblasts (CAFs) which shape the tumor microenvironment (TME) and the presence of blood brain barrier (BBB) remain great challenges in targeting breast cancer and its brain metastasis. Herein, we reported a strategy using PTX-loaded liposome co-modified with acid-cleavable folic acid (FA) and BBB transmigrating cell penetrating peptide dNP2 peptide (cFd-Lip/PTX) for enhanced delivery to orthotopic breast cancer and its brain metastasis. Compared with single ligand or non-cleavable Fd modified liposomes, cFd-Lip exhibited synergistic TME targeting and BBB transmigration. Moreover, upon arrival at the TME, the acid-cleavable cFd-Lip/PTX showed sensitive cleavage of FA, which reduced the hindrance effect and maximized the function of both FA and dNP2 peptide. Consequently, efficient targeting of folate receptor (FR)-positive tumor cells and FR-negative CAFs was achieved, leading to enhanced anti-tumor activity. This strategy provides a feasible approach to the cascade targeting of TME and BBB transmigration in orthotopic and metastatic cancer treatment.

Proteomic Analysis of Cancer-Associated Fibroblasts Reveals a Paracrine Role for MFAP5 in Human Oral Tongue Squamous Cell Carcinoma

Bidirectional communication between cells and their microenvironment is crucial for both normal tissue homeostasis and tumor growth. During the development of oral tongue squamous cell carcinoma (OTSCC), cancer-associated fibroblasts (CAFs) create a supporting niche by maintaining a bidirectional crosstalk with cancer cells, mediated by classically secreted factors and various nanometer-sized vesicles, termed as extracellular vesicles (EVs). To better understand the role of CAFs within the tumor stroma and elucidate the mechanism by which secreted proteins contribute to OTSCC progression, we isolated and characterized patient-derived CAFs from resected tumors with matched adjacent tissue fibroblasts (AFs). Our strategy employed shotgun proteomics to comprehensively characterize the proteomes of these matched fibroblast populations. Our goals were to identify CAF-secreted factors (EVs and soluble) that can functionally modulate OTSCC cells in vitro and to identify novel CAF-associated biomarkers. Comprehensive proteomic analysis identified 4247 proteins, the most detailed description of a pro-tumorigenic stroma to date. We demonstrated functional effects of CAF secretomes (EVs and conditioned media) on OTSCC cell growth and migration. Comparative proteomics identified novel proteins associated with a CAF-like state. Specifically, MFAP5, a protein component of extracellular microfibrils, was enriched in CAF secretomes. Using in vitro assays, we demonstrated that MFAP5 activated OTSCC cell growth and migration via activation of MAPK and AKT pathways. Using a tissue microarray of richly annotated primary human OTSCCs, we demonstrated an association of MFAP5 expression with patient survival. In summary, our proteomics data of patient-derived stromal fibroblasts provide a useful resource for future mechanistic and biomarker studies.

Upregulation of osteopontin expression via the interaction of macrophages and fibroblasts under IL-1b stimulation

BACKGROUND

Fibrosis is attributed to dysregulation of tissue-remodeling. In remodeling areas, fibroblasts and macrophages actively make contact with each other. Osteopontin (OPN) is a pro-fibrotic molecule, whose expression is upregulated by interleukin (IL)-1β via secretion of its downstream cytokines, such as IL-6. Here, we investigated the effect of interaction between fibroblasts and macrophages under IL-1β stimulation on the expression of OPN.

METHODS

We used human lung fibroblasts and THP-1 macrophages differentiated from THP-1 cells using phorbol 12-myristate 13-acetate. These cells were either cultured alone or co-cultured under IL-1β stimulation. Secretion of OPN and IL-6 were examined by enzyme-linked immunosorbent assay, and mRNA expression was assessed by quantitative real-time PCR. The effects of siRNA against IL-6 or OPN on OPN expression were evaluated.

RESULTS

OPN expression increased when fibroblasts and THP-1 macrophages were co-cultured under IL-1β stimulation. The siRNA against IL-6 in fibroblasts suppressed the upregulation of OPN expression during co-culture, whereas siRNA against IL-6 in THP-1 macrophages did not. The upregulation of expression of OPN mRNA in fibroblasts or THP-1 macrophages when co-cultured under IL-1β stimulation was mediated by IL-6 from fibroblasts. OPN from THP-1 macrophages was involved in the increase of OPN expression in fibroblasts.

CONCLUSIONS

The present study revealed the crosstalk between fibroblasts and THP-1 macrophages under IL-1β stimulation, where IL-6 from fibroblasts, stimulated by IL-1β, upregulated OPN expression in fibroblasts themselves via increase in OPN from THP-1 macrophages. The fibroblasts/macrophages network may induce activation or qualitative changes in both cells, which contributes to inflammation-associated fibrosis.

Reshaping the Tumor Stroma for Treatment of Pancreatic Cancer

Pancreatic cancer is accompanied by a fibrotic reaction that alters interactions between tumor cells and the stroma to promote tumor progression. Consequently, strategies to target the tumor stroma might be used to treat patients with pancreatic cancer. We review recently developed approaches for reshaping the pancreatic tumor stroma and discuss how these might improve patient outcomes. We also describe relationships between the pancreatic tumor extracellular matrix, the vasculature, the immune system, and metabolism, and discuss the implications for the development of stromal compartment-specific therapies.

Tumor-derived exosomal miR-1247-3p induces cancer-associated fibroblast activation to foster lung metastasis of liver cancer

The communication between tumor-derived elements and stroma in the metastatic niche has a critical role in facilitating cancer metastasis. Yet, the mechanisms tumor cells use to control metastatic niche formation are not fully understood. Here we report that in the lung metastatic niche, high-metastatic hepatocellular carcinoma (HCC) cells exhibit a greater capacity to convert normal fibroblasts to cancer-associated fibroblasts (CAFs) than low-metastatic HCC cells. We show high-metastatic HCC cells secrete exosomal miR-1247-3p that directly targets B4GALT3, leading to activation of β1-integrin–NF-κB signaling in fibroblasts. Activated CAFs further promote cancer progression by secreting pro-inflammatory cytokines, including IL-6 and IL-8. Clinical data show high serum exosomal miR-1247-3p levels correlate with lung metastasis in HCC patients. These results demonstrate intercellular crosstalk between tumor cells and fibroblasts is mediated by tumor-derived exosomes that control lung metastasis of HCC, providing potential targets for prevention and treatment of cancer metastasis.

How tumor cells control metastatic niche formation is not fully understood. Here, the authors show in a lung metastatic niche, high-metastatic hepatocellular carcinoma cells secrete exosomal miR-1247-3p that leads to activation of β1-integrin-NF-κBsignalling, converting fibroblasts to cancer-associated fibroblasts.

Inflammation fires up cancer metastasis

Metastatic disease is the major challenge of cancer that accounts for over 90% of total cancer lethality. Mounting clinical and preclinical data now indicate that inflammation, a potent immune and repair response, is indispensable for metastasis. In this review we describe our current understanding of how major inflammatory cells contribute to metastatic cascade with a focus on the primary tumour. We also discuss exciting new directions for future research and novel therapeutic approaches to tackle metastatic disease through targeting inflammation.

Unfavorable effect of calcitriol and its low-calcemic analogs on metastasis of 4T1 mouse mammary gland cancer

Low vitamin D status is considered as a risk factor for breast cancer and has prognostic significance. Furthermore, vitamin D deficiency increases after adjuvant cancer therapy, which alters bone metabolism increasing the risk of osteoporosis. It is now postulated that vitamin D supplementation in breast cancer treatment delays the recurrence of cancer thereby extending survival. We evaluated the impact of calcitriol and its low-calcemic analogs, PRI-2191 and PRI-2205, on the tumor growth, angiogenesis, and metastasis of 4T1 mouse mammary gland cancer. Gene expression analysis related to cancer invasion/metastasis, real-time PCR, ELISA, western blotting, and histochemical studies were performed. In vitro studies were conducted to compare the effects of calcitriol and its analogs on 4T1 and 67NR cell proliferation and expression of selected proteins. Calcitriol and its analogs increased lung metastasis without influencing the growth of primary tumor. The levels of plasma 17β-estradiol and transforming growth factor β (TGFβ) were found to be elevated after treatment. Moreover, the results showed that tumor blood perfusion improved and osteopontin (OPN) levels increased, whereas vascular endothelial growth factor (VEGF) and TGFβ levels decreased in tumors from treated mice. All the studied treatments resulted in increased collagen content in the tumor tissue in the early step of tumor progression, and calcitriol caused an increase in collagen content in lung tissue. In addition, in vitro proliferation of 4T1 tumor cells was not found to be affected by calcitriol or its analogs in contrast to non-metastatic 67NR cells. Calcitriol and its analogs enhanced the metastatic potential of 4T1 mouse mammary gland cancer by inducing the secretion of OPN probably via host cells. In addition, OPN tumor overexpression prevailed over the decreasing tumor TGFβ level and blood vessel normalization via tumor VEGF deprivation induced by calcitriol and its analogs. Moreover, the increased plasma TGFβ and 17β-estradiol levels contributed to the facilitation of metastatic process.

Prognostic role of pretreatment neutrophil to lymphocyte ratio in breast cancer patients: A meta-analysis

BACKGROUND

Inflammation and cancer are closely related to each other. As a parameter that can reflect inflammation and host immune reaction, elevated blood neutrophil to lymphocyte ratio (NLR) has been confirmed to be correlated with poor prognosis in a variety of cancers. However, this remains controversial in breast cancer. Thus, we performed this updated meta-analysis to further clarify whether high NLR could be a predictor of survival in breast cancer patients.

METHODS

We searched on PubMed Database and Cochrane Library. Overall survival (OS), disease-free survival (DFS), and cancer-specific survival were used as outcome events, and hazard ratio (HR) was chosen as the parameter to evaluate the correlation.

RESULT

Eighteen eligible studies were involved in this meta-analysis. The synthesized analysis demonstrated that elevated NLR was associated with poor DFS [HR = 1.72, 95% confidence interval (95% CI) = 1.30-2.27], OS (HR = 1.87, 95% CI = 1.41-2.48), and cancer-specific survival (HR = 2.09, 95% CI = 1.04-4.21). The correlation was stronger in triple-negative breast cancer (TNBC) (OS: HR = 2.58, 95% CI = 1.63-4.06; DFS: HR = 3.51, 95% CI = 1.97-6.24).

CONCLUSION

Higher NLR was correlated to poor prognosis of breast cancer patients. As a clinical parameter that we can easily obtain, NLR might be a potential predictor in patients' survival to assist with physicians' treatment decisions.