Prognostic relevance of cancer-associated fibroblasts in human cancer

COX-2 expression and effects of celecoxib in addition to standard chemotherapy in advanced non-small cell lung cancer

AIM

Inhibition of cyclooxygenase-2 (COX-2) is proposed as a treatment option in several cancer types. However, in non-small cell lung cancer (NSCLC), phase III trials have failed to demonstrate a benefit of adding COX-2 inhibitors to standard chemotherapy. The aim of this study was to analyze COX-2 expression in tumor and stromal cells as predictive biomarker for COX-2 inhibition.

METHODS

In a multicenter phase III trial, 316 patients with advanced NSCLC were randomized to receive celecoxib (400 mg b.i.d.) or placebo up to one year in addition to a two-drug platinum-based chemotherapy combination. In a subset of 122 patients, archived tumor tissue was available for immunohistochemical analysis of COX-2 expression in tumor and stromal cells. For each compartment, COX-2 expression was graded as high or low, based on a product score of extension and intensity of positively stained cells.

RESULTS

An updated analysis of all 316 patients included in the original trial, and of the 122 patients with available tumor tissue, showed no survival differences between the celecoxib and placebo arms (HR 1.01; 95% CI 0.81-1.27 and HR 1.12; 95% CI 0.78-1.61, respectively). High COX-2 scores in tumor (n = 71) or stromal cells (n = 55) was not associated with a superior survival outcome with celecoxib vs. placebo (HR =0.96, 95% CI 0.60-1.54; and HR =1.51; 95% CI 0.86-2.66), and no significant interaction effect between COX-2 score in tumor or stromal cells and celecoxib effect on survival was detected (p = .48 and .25, respectively).

CONCLUSIONS

In this subgroup analysis of patients with advanced NSCLC treated within the context of a randomized trial, we could not detect any interaction effect of COX-2 expression in tumor or stromal cells and the outcome of celecoxib treatment in addition to standard chemotherapy.

CD10+GPR77+ Cancer-Associated Fibroblasts Promote Cancer Formation and Chemoresistance by Sustaining Cancer Stemness

Carcinoma-associated fibroblasts (CAFs) are abundant and heterogeneous stromal cells in tumor microenvironment that are critically involved in cancer progression. Here, we demonstrate that two cell-surface molecules, CD10 and GPR77, specifically define a CAF subset correlated with chemoresistance and poor survival in multiple cohorts of breast and lung cancer patients. CD10⁺GPR77⁺ CAFs promote tumor formation and chemoresistance by providing a survival niche for cancer stem cells (CSCs). Mechanistically, CD10⁺GPR77⁺ CAFs are driven by persistent NF-κB activation via p65 phosphorylation and acetylation, which is maintained by complement signaling via GPR77, a C5a receptor. Furthermore, CD10⁺GPR77⁺ CAFs promote successful engraftment of patient-derived xenografts (PDXs), and targeting these CAFs with a neutralizing anti-GPR77 antibody abolishes tumor formation and restores tumor chemosensitivity. Our study reveals a functional CAF subset that can be defined and isolated by specific cell-surface markers and suggests that targeting the CD10⁺GPR77⁺ CAF subset could be an effective therapeutic strategy against CSC-driven solid tumors.

The application of the fibroblast activation protein α-targeted immunotherapy strategy

Cancer immunotherapy has primarily been focused on attacking tumor cells. However, given the close interaction between tumor cells and cancer-associated fibroblasts (CAFs) in the tumor microenvironment (TME), CAF-targeted strategies could also contribute to an integrated cancer immunotherapy. Fibroblast activation protein α (FAP α) is not detectible in normal tissues, but is overexpressed by CAFs and is the predominant component of the stroma in most types of cancer. FAP α has both dipeptidyl peptidase and endopeptidase activities, cleaving substrates at a post-proline bond. When all FAP α-expressing cells (stromal and cancerous) are destroyed, tumors rapidly die. Furthermore, a FAP α antibody, FAP α vaccine, and modified vaccine all inhibit tumor growth and prolong survival in mouse models, suggesting FAP α is an adaptive tumor-associated antigen. This review highlights the role of FAP α in tumor development, explores the relationship between FAP α and immune suppression in the TME, and discusses FAP α as a potential immunotherapeutic target.

Functional profiling of microtumors to identify cancer associated fibroblast-derived drug targets

Recent advances in chemotherapeutics highlight the importance of molecularly-targeted perturbagens. Although these therapies typically address dysregulated cancer cell proteins, there are increasing therapeutic modalities that take into consideration cancer cell-extrinsic factors. Targeting components of tumor stroma such as vascular or immune cells has been shown to represent an efficacious approach in cancer treatment. Cancer-associated fibroblasts (CAFs) exemplify an important stromal component that can be exploited in targeted therapeutics, though their employment in drug discovery campaigns has been relatively minimal due to technical logistics in assaying for CAF-tumor interactions. Here we report a 3-dimensional multi-culture tumor:CAF spheroid phenotypic screening platform that can be applied to high-content drug discovery initiatives. Using a functional genomics approach we systematically profiled 1,024 candidate genes for CAF-intrinsic anti-spheroid activity; identifying several CAF genes important for development and maintenance of tumor:CAF co-culture spheroids. Along with previously reported genes such as WNT, we identify CAF-derived targets such as ARAF and COL3A1 upon which the tumor compartment depends for spheroid development. Specifically, we highlight the G-protein-coupled receptor OGR1 as a unique CAF-specific protein that may represent an attractive drug target for treating colorectal cancer. In vivo, murine colon tumor implants in OGR1 knockout mice displayed delayed tumor growth compared to tumors implanted in wild type littermate controls. These findings demonstrate a robust microphysiological screening approach for identifying new CAF targets that may be applied to drug discovery efforts.

Classifying the evolutionary and ecological features of neoplasms

Neoplasms change over time through a process of cell-level evolution, driven by genetic and epigenetic alterations. However, the ecology of the microenvironment of a neoplastic cell determines which changes provide adaptive benefits. There is widespread recognition of the importance of these evolutionary and ecological processes in cancer, but to date, no system has been proposed for drawing clinically relevant distinctions between how different tumours are evolving. On the basis of a consensus conference of experts in the fields of cancer evolution and cancer ecology, we propose a framework for classifying tumours that is based on four relevant components. These are the diversity of neoplastic cells (intratumoural heterogeneity) and changes over time in that diversity, which make up an evolutionary index (Evo-index), as well as the hazards to neoplastic cell survival and the resources available to neoplastic cells, which make up an ecological index (Eco-index). We review evidence demonstrating the importance of each of these factors and describe multiple methods that can be used to measure them. Development of this classification system holds promise for enabling clinicians to personalize optimal interventions based on the evolvability of the patient's tumour. The Evo- and Eco-indices provide a common lexicon for communicating about how neoplasms change in response to interventions, with potential implications for clinical trials, personalized medicine and basic cancer research.

Discovery of Stromal Regulatory Networks that Suppress Ras-Sensitized Epithelial Cell Proliferation

Mesodermal cells signal to neighboring epithelial cells to modulate their proliferation in both normal and disease states. We adapted a Caenorhabditis elegans organogenesis model to enable a genome-wide mesodermal-specific RNAi screen and discovered 39 factors in mesodermal cells that suppress the proliferation of adjacent Ras pathway-sensitized epithelial cells. These candidates encode components of protein complexes and signaling pathways that converge on the control of chromatin dynamics, cytoplasmic polyadenylation, and translation. Stromal fibroblast-specific deletion of mouse orthologs of several candidates resulted in the hyper-proliferation of mammary gland epithelium. Furthermore, a 33-gene signature of human orthologs was selectively enriched in the tumor stroma of breast cancer patients, and depletion of these factors from normal human breast fibroblasts increased proliferation of co-cultured breast cancer cells. This cross-species approach identified unanticipated regulatory networks in mesodermal cells with growth-suppressive function, exposing the conserved and selective nature of mesodermal-epithelial communication in development and cancer.

A novel method to generate single-cell-derived cancer-associated fibroblast clones

BACKGROUND

Cancer-associated fibroblasts (CAFs) communicate with cancer cells to play important roles in tumor progression. However, CAFs have heterogeneous phenotypes and functions. To understand how much of this heterogeneity relates to different biological responses, a more efficient method of generating single-cell-derived CAF clones is required.

METHOD

We transduced two primary CAF cultures (CAFs-608 and CAFs-621) from lung adenocarcinoma with human telomerase reverse transcriptase (hTERT), mutant forms of cyclin dependent kinase 4 (CDK4R24C) independently and in combination (hTERT/CDK4R24C). After live imaging of each sorted-single cell, we evaluated the numbers of successfully established clones from CAFs-hTERT, CAFs-CDK4R24C, and CAFs-hTERT/CDK4R24C. Furthermore, we examined the expression levels of genes associated with tumor promoting pathways in established clones by qRT-PCR.

RESULTS

Overexpression of hTERT and CDK4R24C efficiently extended the lifespan of both CAFs-608 and CAFs-621. The number of established CAF clones was highest for CAFs-hTERT/CDK4R24C, with 57 and 62 clones established from CAFs-608 and CAFs-621, respectively. Conversely, 16 and 11 CAFs-hTERT clones were derived from CAFs-608 and CAFs-621, respectively and 10 and 8 CAFs-CDK4R24C clones were from CAFs-608 and CAFs-621, respectively. TGF-b, ATCA2, and HSF1 mRNA levels differed in individual clones established from CAFs-hTERT/CDK4R24C. The expression levels of ATCA2 and HSF1 were much higher in one clone than in the other established clones and the parental CAFs.

CONCLUSION

Our results show that combined exogenous expression of hTERT and mutant CDK4 is an effective method to generate single-cell-derived CAF clones. This provides an innovative and suitable approach to investigate the heterogeneous function and phenotype of CAFs.

DNA methylation-based immune response signature improves patient diagnosis in multiple cancers

BACKGROUND

The tumor immune response is increasingly associated with better clinical outcomes in breast and other cancers. However, the evaluation of tumor-infiltrating lymphocytes (TILs) relies on histopathological measurements with limited accuracy and reproducibility. Here, we profiled DNA methylation markers to identify a methylation of TIL (MeTIL) signature that recapitulates TIL evaluations and their prognostic value for long-term outcomes in breast cancer (BC).

METHODS

MeTIL signature scores were correlated with clinical endpoints reflecting overall or disease-free survival and a pathologic complete response to preoperative anthracycline therapy in 3 BC cohorts from the Jules Bordet Institute in Brussels and in other cancer types from The Cancer Genome Atlas.

RESULTS

The MeTIL signature measured TIL distributions in a sensitive manner and predicted survival and response to chemotherapy in BC better than did histopathological assessment of TILs or gene expression-based immune markers, respectively. The MeTIL signature also improved the prediction of survival in other malignancies, including melanoma and lung cancer. Furthermore, the MeTIL signature predicted differences in survival for malignancies in which TILs were not known to have a prognostic value. Finally, we showed that MeTIL markers can be determined by bisulfite pyrosequencing of small amounts of DNA from formalin-fixed, paraffin-embedded tumor tissue, supporting clinical applications for this methodology.

CONCLUSIONS

This study highlights the power of DNA methylation to evaluate tumor immune responses and the potential of this approach to improve the diagnosis and treatment of breast and other cancers.

FUNDING

This work was funded by the Fonds National de la Recherche Scientifique (FNRS) and Télévie, the INNOVIRIS Brussels Region BRUBREAST Project, the IUAP P7/03 program, the Belgian "Foundation against Cancer," the Breast Cancer Research Foundation (BCRF), and the Fonds Gaston Ithier.

RNA-based ovarian cancer research from 'a gene to systems biomedicine' perspective

Ovarian cancer remains the leading cause of death from a gynecologic malignancy, and treatment of this disease is harder than any other type of female reproductive cancer. Improvements in the diagnosis and development of novel and effective treatment strategies for complex pathophysiologies, such as ovarian cancer, require a better understanding of disease emergence and mechanisms of progression through systems medicine approaches. RNA-level analyses generate new information that can help in understanding the mechanisms behind disease pathogenesis, to identify new biomarkers and therapeutic targets and in new drug discovery. Whole RNA sequencing and coding and non-coding RNA expression array datasets have shed light on the mechanisms underlying disease progression and have identified mRNAs, miRNAs, and lncRNAs involved in ovarian cancer progression. In addition, the results from these analyses indicate that various signalling pathways and biological processes are associated with ovarian cancer. Here, we present a comprehensive literature review on RNA-based ovarian cancer research and highlight the benefits of integrative approaches within the systems biomedicine concept for future ovarian cancer research. We invite the ovarian cancer and systems biomedicine research fields to join forces to achieve the interdisciplinary caliber and rigor required to find real-life solutions to common, devastating, and complex diseases such as ovarian cancer.

ABBREVIATIONS

CAF: cancer-associated fibroblasts; COG: Cluster of Orthologous Groups; DEA: disease enrichment analysis; EOC: epithelial ovarian carcinoma; ESCC: oesophageal squamous cell carcinoma; GSI: gamma secretase inhibitor; GO: Gene Ontology; GSEA: gene set enrichment analyzes; HAS: Hungarian Academy of Sciences; lncRNAs: long non-coding RNAs; MAPK/ERK: mitogen-activated protein kinase/extracellular signal-regulated kinases; NGS: next-generation sequencing; ncRNAs: non-coding RNAs; OvC: ovarian cancer; PI3K/Akt/mTOR: phosphatidylinositol-3-kinase/protein kinase B/mammalian target of rapamycin; RT-PCR: real-time polymerase chain reaction; SNP: single nucleotide polymorphism; TF: transcription factor; TGF-β: transforming growth factor-β.

Evolution of Cancer Stem-like Cells in Endocrine-Resistant Metastatic Breast Cancers Is Mediated by Stromal Microvesicles

The hypothesis that microvesicle-mediated miRNA transfer converts noncancer stem cells into cancer stem cells (CSC) leading to therapy resistance remains poorly investigated. Here we provide direct evidence supporting this hypothesis, by demonstrating how microvesicles derived from cancer-associated fibroblasts (CAF) transfer miR-221 to promote hormonal therapy resistance (HTR) in models of luminal breast cancer. We determined that CAF-derived microvesicles horizontally transferred miR-221 to tumor cells and, in combination with hormone therapy, activated an ERlo/Notchhi feed-forward loop responsible for the generation of CD133hi CSCs. Importantly, microvesicles from patients with HTR metastatic disease expressed high levels of miR-221. We further determined that the IL6-pStat3 pathway promoted the biogenesis of onco-miR-221hi CAF microvesicles and established stromal CSC niches in experimental and patient-derived breast cancer models. Coinjection of patient-derived CAFs from bone metastases led to de novo HTR tumors, which was reversed with IL6R blockade. Finally, we generated patient-derived xenograft (PDX) models from patient-derived HTR bone metastases and analyzed tumor cells, stroma, and microvesicles. Murine and human CAFs were enriched in HTR tumors expressing high levels of CD133hi cells. Depletion of murine CAFs from PDX restored sensitivity to HT, with a concurrent reduction of CD133hi CSCs. Conversely, in models of CD133neg, HT-sensitive cancer cells, both murine and human CAFs promoted de novo HT resistance via the generation of CD133hi CSCs that expressed low levels of estrogen receptor alpha. Overall, our results illuminate how microvesicle-mediated horizontal transfer of genetic material from host stromal cells to cancer cells triggers the evolution of therapy-resistant metastases, with potentially broad implications for their control. Cancer Res; 77(8); 1927-41. ©2017 AACR.

Mesothelial-to-mesenchymal transition as a possible therapeutic target in peritoneal metastasis of ovarian cancer

Peritoneal dissemination is the primary metastatic route of ovarian cancer (OvCa), and is often accompanied by the accumulation of ascitic fluid. The peritoneal cavity is lined by mesothelial cells (MCs), which can be converted into carcinoma‐associated fibroblasts (CAFs) through mesothelial‐to‐mesenchymal transition (MMT). Here, we demonstrate that MCs isolated from ascitic fluid (AFMCs) of OvCa patients with peritoneal implants also undergo MMT and promote subcutaneous tumour growth in mice. RNA sequencing of AFMCs revealed that MMT‐related pathways – including transforming growth factor (TGF)‐β signalling – are differentially regulated, and a gene signature was verified in peritoneal implants from OvCa patients. In a mouse model, pre‐induction of MMT resulted in increased peritoneal tumour growth, whereas interfering with the TGF‐β receptor reduced metastasis. MC‐derived CAFs showed activation of Smad‐dependent TGF‐β signalling, which was disrupted in OvCa cells, despite their elevated TGF‐β production. Accordingly, targeting Smad‐dependent signalling in the peritoneal pre‐metastatic niche in mice reduced tumour colonization, suggesting that Smad‐dependent MMT could be crucial in peritoneal carcinomatosis. Together, these results indicate that bidirectional communication between OvCa cells and MC‐derived CAFs, via TGF‐β‐mediated MMT, seems to be crucial to form a suitable metastatic niche. We suggest MMT as a possible target for therapeutic intervention and a potential source of biomarkers for improving OvCa diagnosis and/or prognosis. © 2017 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

Carcinoma-associated fibroblasts: orchestrating the composition of malignancy

The tumor stroma is no longer seen solely as physical support for mutated epithelial cells but as an important modulator and even a driver of tumorigenicity. Within the tumor stromal milieu, heterogeneous populations of fibroblast-like cells, collectively termed carcinoma-associated fibroblasts (CAFs), are key players in the multicellular, stromal-dependent alterations that contribute to malignant initiation and progression. This review focuses on novel insights into the contributions of CAFs to disease progression, emergent events leading to the generation of CAFs, identification of CAF-specific biomarkers predictive of disease outcome, and recent therapeutic approaches aimed at blunting or reverting detrimental protumorigenic phenotypes associated with CAFs.

Small role with big impact: miRNAs as communicators in the cross-talk between cancer-associated fibroblasts and cancer cells

Cancer microenvironment is composed of numerous components that can support cancer cell proliferation, promote cancer progression and contribute to cancer treatment resistance. The major components of caner microenvironment are fibroblasts, endothelial cells, immune cells as well as cytokines, chemokines, and extracellular matrix (ECM) all of which surround tumor cells as the core and cross talk with each other. Among them, cancer-associated fibroblasts (CAFs) play an important role in promoting cancer progression by secreting various pro-inflammatory factors. MicroRNAs (miRNAs) are small noncoding RNAs that negatively regulate protein expression both in cancer cell and normal stromal cells. Changes of miRNAs expression in cancer-associated fibroblasts can be induced both by cancer cells and other stromal cells. This change can arise through direct interaction or by secreted paracrine factors or even by secreted miRNAs. The desregulated miRNAs in cancer-associated fibroblasts then enhance the CAFs phenotype and assist their cancer promotion ability. Explore the regulatory function of miRNAs in the complex communication between cancer cells and cancer microenvironment is important to understand the process of tumor progression and may help to develop new therapeutic strategies. This review provides an updated content of latest research advances about the relevance of miRNAs in the interaction between cancer cells and the CAFs. We will describe miRNAs which are differential expressed by NFs and CAFs, their function in regulating fibroblasts activation as well as miRNAs expressed in CAFs as prognostic factors in cancer stroma in recent studies. We will also discuss miRNA as an important player in CAFs mediated regulation of cancer progression and metastasis, cancer metabolism, cancer stem cell property and chemoresistance.

Markers of fibroblast-rich tumor stroma and perivascular cells in serous ovarian cancer: Inter- and intra-patient heterogeneity and impact on survival

Inter- and intra-patient variations in tumor microenvironment of serous ovarian cancer are largely unexplored. We aimed to explore potential co-regulation of tumor stroma characteristics, analyze their concordance in primary and metastatic lesions, and study their impact on survival. A tissue microarray (TMA) with 186 tumors and 91 matched metastases was subjected to immunohistochemistry double staining with endothelial cell marker CD34 and fibroblast and pericyte markers α-SMA, PDGFβR and desmin. Images were digitally analyzed to yield “metrics” related to vasculature and stroma features.

Intra-case analyses showed that PDGFβR in perivascular cells and fibroblasts were strongly correlated. Similar findings were observed concerning α-SMA. Most stroma characteristics showed large variations in intra-case comparisons of primary tumors and metastasis. Large PDGFβR-positive stroma fraction and high PDGFβFR positive perivascular intensity were both significantly associated with shorter survival in uni- and multi-variate analyses (HR 1.7, 95% CI 1.1-2.5; HR 1.7, 95% CI 1.1-2.8).

In conclusion, we found PDGFβR- and α-SMA-expression to be largely independent of each other but concordantly activated in perivascular cells and in fibroblasts within the primary tumor. Stromal characteristics differed between primary tumors and metastases. PDGFβR in perivascular cells and in fibroblasts may be novel prognostic markers in serous ovarian cancer.

Establishment of a tumour-stroma airway model (OncoCilAir) to accelerate the development of human therapies against lung cancer

This paper highlights the work for which OncoTheis, a Swiss biotechnology company, engaged in the development of innovative bioengineered tissues and organoids for cancer research, was co-awarded the 2015 Lush Science Prize. Noting that the use of animal models failed to lead to the design of effective treatments for cancer, OncoTheis has opted to develop in vitro models based exclusively on human cells. The company currently focuses on lung cancer, which is the leading cause of cancer-related deaths worldwide, with more than one million deaths per year. To address this public health concern, we developed OncoCilAir™, a new 3-D model that mimics in vitro the progression of the disease as it happens in patients. In this system, bronchial and lung tumour cells obtained from discarded surgical tissue are cocultured in a Petri dish to reconstitute a fragment of the human lung. After appropriate differentiation, the culture closely reproduces malignant pulmonary nodules invading a small piece of functional airway tissue. As OncoCilAir includes both healthy and cancerous tissues, it can be used to test tumour-killing activity and the adverse effects of chemotherapies and other anti-cancer drugs. Moreover, a single culture can be maintained for up to three months, which permits studies of longer-term effects, including the assessment of drug resistance and tumour recurrence. OncoCilAir heralds a new generation of integrated in vitro models, which is expected to increase the quality of preclinical research while replacing animal testing.

Fibroblast miR-210 overexpression is independently associated with clinical failure in Prostate Cancer - a multicenter (in situ hybridization) study

There is a need for better prognostication in prostate cancer (PC). “The micromanager of hypoxia”, microRNA-210 (miR-210) is directly linked to hypoxia, is overexpressed in PC and has been implied in tumor cell-fibroblast crosstalk. We investigated the prognostic impact of miR-210 in tumor cells and fibroblasts in PC. Tumor and stromal samples from a multicenter PC cohort of 535 prostatectomy patients were inserted into tissue microarrays. To investigate the expression of miR-210, we used in situ hybridization and two pathologists semiquantitatively scored its expression. Overexpression of miR-210 in tumor cells was not associated to biochemical failure-free survival (BFFS, p = 0.85) or clinical failure-free survival (CFFS, p = 0.09). However, overexpression of miR-210 in fibroblasts was significantly associated to a poor CFFS (p = 0.001), but not BFFS (p = 0.232). This feature was validated in both cohorts. Overexpression of miR-210 was independently associated with a reduced CFFS (HR = 2.76, CI 95% 1.25–6.09, p = 0.012). Overexpression of miR-210 in fibroblasts is independently associated with a poor CFFS. This highlights the importance of fibroblasts and cellular compartment crosstalk in PC. miR-210 is a candidate prognostic marker and potential therapeutic target in PC.

CXCL1-Mediated Interaction of Cancer Cells with Tumor-Associated Macrophages and Cancer-Associated Fibroblasts Promotes Tumor Progression in Human Bladder Cancer

Tumor-associated macrophages (TAMs) and cancer-associated fibroblasts (CAFs) are reported to be associated with poor prognosis, depending on their pro-tumoral roles. Current knowledge of TAMs and CAFs in the tumor microenvironment of urothelial cancer of the bladder (UCB) is limited. Therefore, we investigated the paracrine effect induced by TAMs and CAFs in the tumor microenvironment of human UCB. For this, we first carried out immunohistochemical analysis for CXCL1, CD204 (TAM marker), αSMA (CAF marker), E-cadherin, and MMP2 using 155 UBC tissue samples. Next, CXCL1-overexpressing clones of THP-1-derived TAMs and NIH3T3-derived CAFs were developed by lentiviral vector infection. The immunohistochemical study showed high CXCL1 levels in UCB cells to be associated with enhanced recruitment of TAMs/CAFs, higher metastatic potential, and poor prognosis. Three-dimensional (3D) co-culture of UCB cells and TAMs/CAFs suggested that CXCL1 production in TAMs/CAFs play an important role in cell-to-cell adhesion and interaction among cancer cells and these stromal cells. CXCL1-expressing TAMs/CAFs enhanced tumor growth of subcutaneous UCB tumors in nude mice when injected together. In addition, an experiment using the orthotopic bladder cancer model revealed that CXCL1 production in TAMs/CAFs supported tumor implantation into the murine bladder wall and UCB growth when injected together, which was confirmed by clinical data of patients with bladder cancer. Thus, CXCL1 signaling in the tumor microenvironment is highly responsible for repeated intravesical recurrence, disease progression, and drug resistance through enhanced invasion ability. In conclusion, disrupting CXCL1 signaling to dysregulate this chemokine is a promising therapeutic approach for human UCB.

A Mimic of the Tumor Microenvironment: A Simple Method for Generating Enriched Cell Populations and Investigating Intercellular Communication

Understanding the early heterotypic interactions between cancer cells and the surrounding non-cancerous stroma is important in elucidating the events leading to stromal activation and establishment of the tumor microenvironment (TME). Several in vitro and in vivo models of the TME have been developed; however, in general these models do not readily permit isolation of individual cell populations, under non-perturbing conditions, for further study. To circumvent this difficulty, we have employed an in vitro TME model using a cell growth substrate consisting of a permeable microporous membrane insert that permits simple generation of highly enriched cell populations grown intimately, yet separately, on either side of the insert's membrane for extended co-culture times. Through use of this model, we are capable of generating greatly enriched cancer-associated fibroblast (CAF) populations from normal diploid human fibroblasts following co-culture (120 hr) with highly metastatic human breast carcinoma cells, without the use of fluorescent tagging and/or cell sorting. Additionally, by modulating the pore-size of the insert, we can control for the mode of intercellular communication (e.g., gap-junction communication, secreted factors) between the two heterotypic cell populations, which permits investigation of the mechanisms underlying the development of the TME, including the role of gap-junction permeability. This model serves as a valuable tool in enhancing our understanding of the initial events leading to cancer-stroma initiation, the early evolution of the TME, and the modulating effect of the stroma on the responses of cancer cells to therapeutic agents.

High expression of stromal PDGFRβ is associated with reduced benefit of tamoxifen in breast cancer

Cancer‐associated fibroblasts (CAFs) regulate tumour growth, metastasis and response to treatment. Recent studies indicate the existence of functionally distinct CAF subsets. Suggested mechanisms whereby CAFs can impact on treatment response include paracrine signalling affecting cancer cell drug sensitivity and effects on tumour drug uptake. PDGFRβ is an important regulator of fibroblasts. Experimental studies have linked PDGFRβ‐positive fibroblasts to metastasis and also to reduced tumour drug uptake. This study has investigated the potential role of PDGFRβ‐positive fibroblasts in response to adjuvant tamoxifen treatment of breast cancer. Analyses of two breast cancer collections from randomised studies analysing adjuvant tamoxifen treatment in early breast cancer demonstrated significant benefit of tamoxifen in the group with low stromal PDGFRβ, which was not observed in the group with high stromal PDGFRβ. In general terms these findings provide novel evidence, derived from analyses of randomised clinical studies, of response‐predictive capacity of a marker‐defined subset of CAFs and, more specifically, identify stromal PDGFRβ as a marker related to tamoxifen benefit in early breast cancer.

The biology and function of fibroblasts in cancer

Among all cells, fibroblasts could be considered the cockroaches of the human body. They survive severe stress that is usually lethal to all other cells, and they are the only normal cell type that can be live-cultured from post-mortem and decaying tissue. Their resilient adaptation may reside in their intrinsic survival programmes and cellular plasticity. Cancer is associated with fibroblasts at all stages of disease progression, including metastasis, and they are a considerable component of the general host response to tissue damage caused by cancer cells. Cancer-associated fibroblasts (CAFs) become synthetic machines that produce many different tumour components. CAFs have a role in creating extracellular matrix (ECM) structure and metabolic and immune reprogramming of the tumour microenvironment with an impact on adaptive resistance to chemotherapy. The pleiotropic actions of CAFs on tumour cells are probably reflective of them being a heterogeneous and plastic population with context-dependent influence on cancer.

The biology and function of fibroblasts in cancer

Among all cells, fibroblasts could be considered the cockroaches of the human body. They survive severe stress that is usually lethal to all other cells, and they are the only normal cell type that can be live-cultured from post-mortem and decaying tissue. Their resilient adaptation may reside in their intrinsic survival programmes and cellular plasticity. Cancer is associated with fibroblasts at all stages of disease progression, including metastasis, and they are a considerable component of the general host response to tissue damage caused by cancer cells. Cancer-associated fibroblasts (CAFs) become synthetic machines that produce many different tumour components. CAFs have a role in creating extracellular matrix (ECM) structure and metabolic and immune reprogramming of the tumour microenvironment with an impact on adaptive resistance to chemotherapy. The pleiotropic actions of CAFs on tumour cells are probably reflective of them being a heterogeneous and plastic population with context-dependent influence on cancer.

The roles of tumor- and metastasis-promoting carcinoma-associated fibroblasts in human carcinomas

Carcinoma-associated fibroblasts (CAFs) constitute a substantial proportion of the non-neoplastic mesenchymal cell compartment in various human tumors. These fibroblasts are phenotypically converted from their progenitors via interactions with nearby cancer cells during the course of tumor progression. The resulting CAFs, in turn, support the growth and progression of carcinoma cells. These fibroblasts have a major influence on the hallmarks of carcinoma and promote tumor malignancy through the secretion of tumor-promoting growth factors, cytokines and exosomes, as well as through the remodeling of the extracellular matrix. Coevolution of CAFs and carcinoma cells during tumorigenesis is therefore essential for progression into fully malignant tumors. Recent studies have revealed the molecular mechanisms underlying CAF functions, especially in tumor invasion, metastasis and drug resistance and have highlighted the significant heterogeneity among these cells. In this review, we summarize the impacts of recently identified roles of tumor-promoting CAFs and discuss the therapeutic implications of targeting the heterotypic interactions of these fibroblasts with carcinoma cells. Graphical Abstract ᅟ.

Interleukin-6 receptor in spindle-shaped stromal cells, a prognostic determinant of early breast cancer

Spindle-shaped stromal cells, like carcinoma-associated fibroblasts and mesenchymal stem cells, influence tumor behavior and can serve as parameters in the clinical diagnosis, therapy, and prognosis of early breast cancer. Therefore, the aim of this study is to explore the clinicopathological significance of tumor necrosis factor-related apoptosis-induced ligand (TRAIL) receptors (Rs) 2 and 4 (TRAIL-R2 and R4), and interleukin-6 R (IL-6R) in spindle-shaped stromal cells, not associated with the vasculature, as prognostic determinants of early breast cancer patients. Receptors are able to trigger the migratory activity, among other functions, of these stromal cells. We conducted immunohistochemical analysis for the expression of these receptors in spindle-shaped stromal cells, not associated with the vasculature, of primary tumors from early invasive breast cancer patients, and analyzed their association with clinicopathological characteristics. Here, we demonstrate that the elevated levels of TRAIL-R2, TRAIL-R4, and IL-6R in these stromal cells were significantly associated with a higher risk of metastatic occurrence (p = 0.034, 0.026, and 0.006; respectively). Moreover, high expression of TRAIL-R4 was associated with shorter disease-free survival and metastasis-free survival (p = 0.013 and 0.019; respectively). Also, high expression of IL-6R was associated with shorter disease-free survival, metastasis-free survival, and overall survival (p = 0.003, 0.001, and 0.003; respectively). Multivariate analysis showed that IL-6R expression was an independent prognostic factor for disease-free survival and metastasis-free survival (p = 0.035). This study is the first to demonstrate that high levels of IL-6R expression in spindle-shaped stromal cells, not associated with the vasculature, could be used to identify early breast cancer patients with poor outcomes.

Transfer of malignant trait to BRCA1 deficient human fibroblasts following exposure to serum of cancer patients

Background

It was reported that metastases might occur via transfer of biologically active blood circulating molecules from the primary tumor to distant organs rather than only migration of cancer cells. We showed in an earlier study that exposure of immortalized human embryonic kidney cells (HEK 293) to cancer patient sera, induce their transformation into undifferentiated cancers due to a horizontal transfer of malignant traits. In the present work, we tested the hypothesis that even other human cells as long as they are deficient for a single oncosuppressor gene might undergo malignant transformation when exposed to human cancer serum.

Methods

We used the CRISPR/Cas9 system to establish a stable BRCA1 knockout (KO) in human fibroblasts. The BRCA1-KO fibroblasts were exposed to cancer patients’ sera or healthy patients’ sera for 2 weeks. Treated cells were analyzed for cell proliferation and transformation to study their susceptibility to the oncogenic potential of cancer patients’ sera and to determine the possible mechanisms underlying their hypothesized transformation.

Results

BRCA1-KO fibroblasts treated with cancer patients’ sera displayed higher proliferation and underwent malignant transformation as opposed to wild type control fibroblasts, which were not affected by exposure to cancer patients’ sera. The malignant transformation was not seen when BRCA1-KO fibroblasts were treated with healthy human sera. Histological analysis of tumors generated by BRCA1-KO fibroblasts showed that they were carcinomas with phenotypical characteristics related to the cancers of the blood donor patients. Interestingly, BRCA1-KO fibroblasts were significantly more prone to internalize serum-derived exosomes, when compared to wild type fibroblasts. This suggests that oncosuppressor genes might protect the integrity of the cell genome also by blocking integration of cancer-derived exosomes.

Conclusion

These data support the hypothesis that any human cells carrying a single oncosuppressor mutation is capable of integrating cancer factors carried in the blood and undergo complete malignant transformation. Oncosuppressor genes might protect the cell genome by impeding the integration inside the cells of these mutating factors.

Electronic supplementary material

The online version of this article (doi:10.1186/s13046-016-0360-9) contains supplementary material, which is available to authorized users.

Preparation and Analysis of In Vitro Three Dimensional Breast Carcinoma Surrogates

Three dimensional (3D) culture is a more physiologically relevant method to model cell behavior in vitro than two dimensional culture. Carcinomas, including breast carcinomas, are complex 3D tissues composed of cancer epithelial cells and stromal components, including fibroblasts and extracellular matrix (ECM). Yet most in vitro models of breast carcinoma consist only of cancer epithelial cells, omitting the stroma and, therefore, the 3D architecture of a tumor in vivo. Appropriate 3D modeling of carcinoma is important for accurate understanding of tumor biology, behavior, and response to therapy. However, the duration of culture and volume of 3D models is limited by the availability of oxygen and nutrients within the culture. Herein, we demonstrate a method in which breast carcinoma epithelial cells and stromal fibroblasts are incorporated into ECM to generate a 3D breast cancer surrogate that includes stroma and can be cultured as a solid 3D structure or by using a perfusion bioreactor system to deliver oxygen and nutrients. Following setup and an initial growth period, surrogates can be used for preclinical drug testing. Alternatively, the cellular and matrix components of the surrogate can be modified to address a variety of biological questions. After culture, surrogates are fixed and processed to paraffin, in a manner similar to the handling of clinical breast carcinoma specimens, for evaluation of parameters of interest. The evaluation of one such parameter, the density of cells present, is explained, where ImageJ and CellProfiler image analysis software systems are applied to photomicrographs of histologic sections of surrogates to quantify the number of nucleated cells per area. This can be used as an indicator of the change in cell number over time or the change in cell number resulting from varying growth conditions and treatments.

Expression of the chemokine CXCL14 in the tumour stroma is an independent marker of survival in breast cancer

Background:

Expression of the chemokine CXCL14 has previously been shown to be elevated in the tumour stroma of, for example, prostate and breast cancer. Cancer-associated fibroblast-derived CXCL14 enhances tumour growth in mouse models of prostate and breast cancer. However, the prognostic significance of compartment-specific expression of CXCL14 has not been studied.

Methods:

CXCL14 mRNA expression was analysed in a breast cancer tissue microarray (TMA) of formalin-fixed, paraffin-embedded tumours by the RNAscope 2.0 Assay. Epithelial and stromal expression was analysed separately and correlated with clinicopathological characteristics and survival.

Results:

CXCL14 was variably and independently expressed in malignant and stromal cells of breast cancer. Total and stromal expression of CXCL14 did not associate with clinicopathological parameters. Epithelial CXCL14 expression was significantly associated with oestrogen receptor α (ERα)-positive tumours and lower proliferation status. Total CXCL14 expression correlated significantly with shorter breast cancer-specific and recurrence-free survival. High stromal, but not epithelial, CXCL14 expression was significantly associated with shorter survival in univariable and multivariable analyses. Moreover, the correlation between stromal CXCL14 expression and survival was more prominent in ER negative, triple negative and basal-like breast cancers.

Conclusions:

The identification of prognostic significance of stromal CXCL14 in breast cancer demonstrates novel clinical relevance of a stroma-derived secreted factor and illustrates the importance of tumour compartment-specific analyses. On the basis of the prognostic signals from difficult-to-treat subgroups, CXCL14 should also be considered as a candidate drug target.

Stromal Palladin Expression Is an Independent Prognostic Factor in Pancreatic Ductal Adenocarcinoma

It has been clear that cancer-associated fibroblasts (CAFs) in the tumor microenvironment play an important role in pancreatic ductal adenocarcinoma (PDAC) progression. However, how CAFs relate to the patients' prognosis and the effects of chemoradiation therapy (CRT) has not been fully investigated. Tissue microarrays (TMAs) representing 167 resected PDACs without preoperative treatment were used for immunohistochemical studies (IHC) of palladin, α-smooth muscle actin (SMA), and podoplanin. Correlations between the expression levels of these markers and clinicopathological findings were analyzed statistically. Whole sections of surgical specimens from PDACs with and without preoperative CRT, designated as the chemotherapy-first group (CF, n = 19) and the surgery-first group (SF, n = 21), respectively, were also analyzed by IHC. In TMAs, the disease-specific survival rate (DSS) at 5 years for all 167 cases was 23.1%. Seventy cases (41.9%) were positive for palladin and had significantly lower DSS (p = 0.0430). α-SMA and podoplanin were positive in 167 cases (100%) and 131 cases (78.4%), respectively, and they were not significantly associated with DSS. On multivariable analysis, palladin expression was an independent poor prognostic factor (p = 0.0243, risk ratio 1.60). In the whole section study, palladin positivity was significantly lower (p = 0.0037) in the CF group (5/19) with a significantly better DSS (p = 0.0144) than in the SF group (16/22), suggesting that stromal palladin expression is a surrogate indicator of the treatment effect after chemoradiation therapy.

[Tumour-stroma interactions in urothelial cancer]

BACKGROUND

The histopathological structure of malignant tumours involves two essential compartments - the tumour parenchyma with the actual transformed cells, and the supportive tumour stroma. The latter consists of specialized mesenchymal cells, such as fibroblasts, macrophages, lymphocytes and vascular cells, as well as of their secreted products, including components of the extracellular matrix, matrix modifying enzymes and numerous regulatory growth factors and cytokines. In consequence, the tumour stroma has the ability to influence virtually all aspects of tumour development and progression, including therapeutic response.

AIM

In this article we review the current knowledge of tumor stroma interactions in urothelial carcinoma and present various experimental systems that are currently in use to unravel the biological basis of these heterotypic cell interactions.

RESULTS

For urothelial carcinoma, an extensive tumour stroma is quite typical and markers of activated fibroblasts correlate significantly with clinical parameters of advanced disease. Another clinically important variable is provided by the stromal expression of syndecan-1.

CONCLUSION

Integration of markers of activated stroma into clinical risk evaluation could aid to better stratification of urothelial bladder carcinoma patients. Elucidation of biological mechanisms underlying tumour-stroma interactions could provide new therapeutical targets.

Characterization of various cell lines from different ampullary cancer subtypes and cancer associated fibroblast-mediated responses

Background

Ampullary cancer is a relatively rare form of cancer and usually treated by pancreatoduodenectomy, followed by adjuvant therapy. The intestinal subtype is associated with markedly improved prognosis after resection. At present, only few cell lines are available for in vitro studies of ampullary cancer and they have not been collectively characterized.

Methods

We characterize five ampullary cancer cell lines by subtype maker expression, epithelial-mesenchymal transition (EMT) features, growth and invasion, drug sensitivity and response to cancer-associated fibroblast conditioned medium (CAF-CM).

Results

On the basis of EMT features, subtype marker expression, growth, invasion and drug sensitivity three types of cell lines could be distinguished: mesenchymal-like, pancreatobiliary-like and intestinal-like. Heterogeneous effects from the cell lines in response to CAF-CM, such as different growth rates, induction of EMT markers as well as suppression of intestinal differentiation markers were observed. In addition, proteomic analysis showed a clear difference in intestinal-like cell line from other cell lines.

Conclusion

Most of the available AMPAC cell lines seem to reflect a poorly differentiated pancreatobiliary or mesenchymal-like phenotype, which is consistent to their origin. We suggest that the most appropriate cell line model for intestinal-like AMPAC is the SNU869, while others seem to reflect aggressive AMPAC subtypes.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-016-2193-5) contains supplementary material, which is available to authorized users.

Carcinoma-Associated Fibroblasts Lead the Invasion of Salivary Gland Adenoid Cystic Carcinoma Cells by Creating an Invasive Track

Carcinoma-associated fibroblasts (CAFs) are critical in determining tumor invasion and metastasis. However the role of CAFs in the invasion of salivary gland adenoid cystic carcinoma (ACC) is poorly understood. In this study, we isolated primary CAFs from two ACC patients. ACC-derived CAFs expressed typical CAF biomarkers and showed increased migration and invasion activity. Conditioned medium collected from CAFs significantly promoted ACC cell migration and invasion. Co-culture of CAFs with ACC cells in a microfluidic device further revealed that CAFs localized at the invasion front and ACC cells followed the track behind the CAFs. Interfering of both matrix metalloproteinase and CXCL12/CXCR4 pathway inhibited ACC invasion promoted by CAFs. Overall, our study demonstrates that ACC-derived CAFs exhibit the most important defining feature of CAFs by promoting cancer invasion. In addition to secretion of soluble factors, CAFs also lead ACC invasion by creating an invasive track in the ECM.

GZD856, a novel potent PDGFRα/β inhibitor, suppresses the growth and migration of lung cancer cells in vitro and in vivo

Platelet-derived growth factor receptors (PDGFRα/β) play critical roles in the autocrine-stimulated growth and recruitment of cancer-associated fibroblasts (CAFs) of human lung cancer cells. We have identified GZD856 as a new PDGFR inhibitor that potently inhibits PDGFRα/β kinase activity and blocks this signaling pathway in lung cancer cells both in vitro and in vivo. GZD856 strongly suppresses the proliferation of PDGFRα-amplified H1703 (PDGFRβ(-)) human lung cancer cells and demonstrates significant in vivo antitumor efficacy in a xenograft mouse model. Although GZD856 displays only limited in vitro antiproliferative efficiency against PDGFRα(-)/PDGFRβ(+) A549 lung cancer cells, it efficiently inhibits the in vivo growth and metastasis of A549 cancer cells in xenograft and orthotopic models, respectively. The promising in vivo antitumor activity of GZD856 in A549 models may result from its suppression of PDGFR-related microenvironment factors, such as recruitment of CAFs and collagen content in stromal cells. GZD856 may be considered as a promising new candidate for anti-lung cancer drug development.

Melanoma Cells Block PEDF Production in Fibroblasts to Induce the Tumor-Promoting Phenotype of Cancer-Associated Fibroblasts

Loss of pigment epithelium-derived factor (PEDF, SERPINF1) in cancer cells is associated with poor prognosis and metastasis, but the contribution of stromal PEDF to cancer evolution is poorly understood. Therefore, we investigated the role of fibroblast-derived PEDF in melanoma progression. We demonstrate that normal dermal fibroblasts expressing high PEDF levels attenuated melanoma growth and angiogenesis in vivo, whereas PEDF-depleted fibroblasts exerted tumor-promoting effects. Accordingly, mice with global PEDF knockout were more susceptible to melanoma metastasis. We also demonstrate that normal fibroblasts in close contact with PEDF-null melanoma cells lost PEDF expression and tumor-suppressive properties. Further mechanistic investigations underlying the crosstalk between tumor and stromal cells revealed that melanoma cells produced PDGF-BB and TGFβ, which blocked PEDF production in fibroblasts. Notably, cancer-associated fibroblasts (CAF) isolated from patient-derived tumors expressed markedly low levels of PEDF. Treatment of patient CAF and TGFβ-treated normal fibroblasts with exogenous PEDF decreased the expression of CAF markers and restored PEDF expression. Finally, expression profiling of PEDF-depleted fibroblasts revealed induction of IL8, SERPINB2, hyaluronan synthase-2, and other genes associated with tumor promotion and metastasis. Collectively, our results demonstrate that PEDF maintains tumor-suppressive functions in fibroblasts to prevent CAF conversion and illustrate the mechanisms by which melanoma cells silence stromal PEDF to promote malignancy. Cancer Res; 76(8); 2265-76. ©2016 AACR.

A proteomics-based approach identifies secreted protein acidic and rich in cysteine as a prognostic biomarker in malignant pleural mesothelioma

Background:

We aimed to identify prognostic blood biomarkers using proteomics-based approaches in malignant pleural mesothelioma (MPM).

Methods:

Plasma samples from 12 MPM patients were used for exploratory mass spectrometry and ELISA analyses. The significance of secreted protein acidic and rich in cysteine (SPARC) was examined in sera from a Dutch series (n=97). To determine the source of the circulating SPARC, we investigated SPARC expression in MPM tumours and healthy controls, as well as the expression and secretion from cell lines and xenografts.

Results:

Secreted protein acidic and rich in cysteine was identified as a putative prognostic marker in plasma. Validation in the Dutch series showed that the median survival was higher in patients with low SPARC compared with those with high SPARC (19.0 vs 8.8 months; P=0.01). In multivariate analyses, serum SPARC remained as an independent predictor (HR 1.55; P=0.05). In MPM tumour samples, SPARC was present in the tumour cells and stromal fibroblasts. Cellular SPARC expression was higher in 5 out of 7 cell lines compared with two immortalized mesothelial lines. Neither cell lines nor xenograft tumours secreted detectable SPARC.

Conclusions:

Low circulating SPARC was associated with favourable prognosis. Secreted protein acidic and rich in cysteine was present in both tumour cells and stromal fibroblasts; and our in vitro and in vivo experiments suggest that stromal fibroblasts are a potential source of circulating SPARC.

Cancer cell invasion driven by extracellular matrix remodeling is dependent on the properties of cancer-associated fibroblasts

PURPOSE

As one form of tumor invasion, cancer cells can invade the extracellular matrix (ECM) through tracks that have been physically remodeled by cancer-associated fibroblasts (CAFs). However, CAFs are a heterogeneous population with diverse matrix-remodeling capacities. The purpose of this study was to investigate how CAFs with various matrix-remodeling capacities influence cancer cell invasion.

METHODS

We established single-cell-derived clones from three primary cultures of CAFs from lung adenocarcinoma patients (Case 1, 5 clones; Case 2, 5 clones; and Case 3, 7 clones). Using a co-culture model, we evaluated the correlations between the number of invaded cancer cells and the remodeling areas generated by CAF clones in each case.

RESULTS

When A549 lung adenocarcinoma cells and CAF clones were co-cultured, both the numbers of invaded cancer cells and the remodeling areas generated by the CAF clones varied greatly. The number of invaded cancer cells was moderately and strongly correlated with the remodeling areas generated by each CAF clone originating from Cases 1 and 2 (R(2) value = 0.53 and 0.68, respectively), suggesting that the remodeling areas in the ECM may determine the number of invaded cancer cells. In contrast, the number of invaded cancer cells was not correlated with the remodeling areas generated by CAF clones originating from Case 3, suggesting that factors other than the remodeling areas might determine the number of invading cancer cells.

CONCLUSIONS

These findings showed two types of fibroblast-dependent cancer cell invasion that are dependent on and independent of the remodeling areas generated by CAFs.

Isolation of CD 90+ Fibroblast/Myofibroblasts from Human Frozen Gastrointestinal Specimens

Fibroblasts/myofibroblasts (MFs) have been gaining increasing attention for their role in pathogenesis and their contributions to both wound healing and promotion of the tumor microenvironment. While there are currently many techniques for the isolation of MFs from gastrointestinal (GI) tissues, this protocol introduces a novel element of isolation of these stromal cells from frozen tissue. Freezing GI tissue specimens not only allows the researcher to acquire samples from worldwide collaborators, biobanks, and commercial vendors, it also permits the delayed processing of fresh samples. The described protocol will consistently yield characteristic spindle-shaped cells with the MF phenotype that express the markers CD90, α-SMA and vimentin. As these cells are derived from patient samples, the use of primary cells also confers the benefit of closely mimicking MFs from disease states-namely cancer and inflammatory bowel diseases. This technique has been validated in gastric, small bowel, and colonic MF primary culture generation. Primary MF cultures can be used in a vast array of experiments over a number of passage and their purity assessed by both immunocytochemistry and flow cytometry analysis.

Molecular Targeting of Integrins and Integrin-Associated Signaling Networks in Radiation Oncology

Radiation and chemotherapy are the main pillars of the current multimodal treatment concept for cancer patients. However, tumor recurrences and resistances still hamper treatment success regardless of advances in radiation beam application, particle radiotherapy, and optimized chemotherapeutics. To specifically intervene at key recurrence- and resistance-promoting molecular processes, the development of potent and specific molecular-targeted agents is demanded for an efficient, safe, and simultaneous integration into current standard of care regimens. Potential targets for such an approach are integrins conferring structural and biochemical communication between cells and their microenvironment. Integrin binding to extracellular matrix activates intracellular signaling for regulating essential cellular functions such as survival, proliferation, differentiation, adhesion, and cell motility. Tumor-associated characteristics such as invasion, metastasis, and radiochemoresistance also highly depend on integrin function. Owing to their dual functionality and their overexpression in the majority of human malignancies, integrins present ideal and accessible targets for cancer therapy. In the following chapter, the current knowledge on aspects of the tumor microenvironment, the molecular regulation of integrin-dependent radiochemoresistance and current approaches to integrin targeting are summarized.

Estrogen receptors in breast carcinogenesis and endocrine therapy

Excessive exposure to estrogen has long been associated with an increased risk for developing breast cancer and anti-estrogen therapy is the gold standard of care in the treatment of estrogen receptor (ER) α-positive breast cancers. However, there are several mysteries concerning both anti-estrogen, tamoxifen, and estrogen. The most important of these are: (1) some ERα-positive breast cancers do not respond to tamoxifen; (2) some ERα-negative breast cancers do respond to tamoxifen; (3) initial or acquired resistance to tamoxifen occurs with recurrent tumors; (4) estrogen can cause marked tumor regression in long-term tamoxifen-resistant ERα-positive breast cancer. These mysteries indicate that we do not know enough about estrogen signaling to understand the effects of targeting these receptors in cancer. The discovery of ERβ, the second estrogen receptor, has added another level of complexity to estrogen signaling. This review summarizes recent publications and makes an updated portrait of ERα and ERβ in breast carcinogenesis and endocrine cancer therapy.

Microenvironment and endocrine resistance in breast cancer: Friend or foe?

Breast cancer affects one in eight women around the world. Seventy five percent of these patients have tumors that are estrogen receptor positive and as a consequence receive endocrine therapy. However, about one third eventually develop resistance and cancer reappears. In the last decade our vision of cancer has evolved to consider it more of a tissue-related disease than a cell-centered one. This editorial argues that we are only starting to understand the role the tumor microenvironment plays in therapy resistance in breast cancer. The development of new therapeutic strategies that target the microenvironment will come when we clearly understand this extremely complicated scenario. As such, and as a scientific community, we have extremely challenging work ahead. We share our views regarding these matters.

Uncovering the dual role of RHAMM as an HA receptor and a regulator of CD44 expression in RHAMM-expressing mesenchymal progenitor cells

The interaction of hyaluronan (HA) with mesenchymal progenitor cells impacts trafficking and fate after tissue colonization during wound repair and these events contribute to diseases such as cancer. How this interaction occurs is poorly understood. Using 10T½ cells as a mesenchymal progenitor model and fluorescent (F-HA) or gold-labeled HA (G-HA) polymers, we studied the role of two HA receptors, RHAMM and CD44, in HA binding and uptake in non-adherent and adherent mesenchymal progenitor (10T½) cells to mimic aspects of cell trafficking and tissue colonization. We show that fluorescent labeled HA (F-HA) binding/uptake was high in non-adherent cells but dropped over time as cells became increasingly adherent. Non-adherent cells displayed both CD44 and RHAMM but only function-blocking anti-RHAMM and not anti-CD44 antibodies significantly reduced F-HA binding/uptake. Adherent cells, which also expressed CD44 and RHAMM, primarily utilized CD44 to bind to F-HA since anti-CD44 but not anti-RHAMM antibodies blocked F-HA uptake. RHAMM overexpression in adherent 10T½ cells led to increased F-HA uptake but this increased binding remained CD44 dependent. Further studies showed that RHAMM-transfection increased CD44 mRNA and protein expression while blocking RHAMM function reduced expression. Collectively, these results suggest that cellular microenvironments in which these receptors function as HA binding proteins differ significantly, and that RHAMM plays at least two roles in F-HA binding by acting as an HA receptor in non-attached cells and by regulating CD44 expression and display in attached cells. Our findings demonstrate adhesion-dependent mechanisms governing HA binding/ uptake that may impact development of new mesenchymal cell-based therapies.

The Mesothelial Origin of Carcinoma Associated-Fibroblasts in Peritoneal Metastasis

Solid tumors are complex and unstructured organs that, in addition to cancer cells, also contain other cell types. Carcinoma-associated fibroblasts (CAFs) represent an important population in the tumor microenviroment and participate in several stages of tumor progression, including cancer cell migration/invasion and metastasis. During peritoneal metastasis, cancer cells detach from the primary tumor, such as ovarian or gastrointestinal, disseminate through the peritoneal fluid and colonize the peritoneum. Tumor cells metastasize by attaching to and invading through the mesothelial cell (MC) monolayer that lines the peritoneal cavity, then colonizing the submesothelial compact zone where CAFs accumulate. CAFs may derive from different sources depending on the surrounding metastatic niche. In peritoneal metastasis, a sizeable subpopulation of CAFs originates from MCs through a mesothelial-to-mesenchymal transition (MMT), which promotes adhesion, invasion, vascularization and subsequent tumor growth. The bidirectional communication between cancer cells and MC-derived CAFs via secretion of a wide range of cytokines, growth factors and extracellular matrix components seems to be crucial for the establishment and progression of the metastasis in the peritoneum. This manuscript provides a comprehensive review of novel advances in understanding how peritoneal CAFs provide cancer cells with a supportive microenvironment, as well as the development of future therapeutic approaches by interfering with the MMT in the peritoneum.

Complexity in the tumour microenvironment: Cancer associated fibroblast gene expression patterns identify both common and unique features of tumour-stroma crosstalk across cancer types

Cancer is a complex disease, driven by the accumulation of several somatic aberrations but fostered by a two-way interaction between tumour cells and the surrounding microenvironment. Cancer associated fibroblasts (CAFs) represent one of the major players in tumour-stroma crosstalk. Recent in vitro and in vivo studies, often conducted by employing high throughput approaches, have started unravelling the key pathways involved in their functional effects. This review focus on open challenges in the study of CAF properties and function, highlighting at the same time the existence of common mechanisms as well as peculiarities in different cancer types (breast, prostate and lung cancer). Although still limited by current experimental models, which are unable to deal with the full level of complexity of the tumour microenvironment, a better understanding of these mechanisms may enable the identification of new biomarkers and therapeutic targets, to improve current strategies for cancer diagnosis and treatment.

The Prognostic Value of Forkhead Box P3 Expression in Operable Breast Cancer: A Large-Scale Meta-Analysis

BACKGROUND

Recent studies have shown that the forkhead box P3 (FOXP3) protein has a prognostic role in breast cancer. However, these results are controversial. Therefore, the aim of this meta-analysis was to clarify the prognostic role of FOXP3 expression in operable breast cancer cases.

METHODS

Eligible studies describing the use of FOXP3 as a prognostic factor for operable breast cancer cases were identified. Clinicopathological features, disease-free survival (DFS), and overall survival (OS) data were collected from these studies and were analyzed using Stata software.

RESULTS

A total of 16 articles containing data from 13,217 breast cancer patients met the inclusion criteria established for this study. The subsequent meta-analysis that was performed showed that high levels of FOXP3 are not significantly associated with DFS and OS with significant heterogeneity. An additional subgroup analysis demonstrated that intratumoral FOXP3+ regulatory T cells (Tregs) were positively correlated with adverse clinicopathological parameters, yet they did not show an association with DFS or OS. For tumor cells, the pooled results revealed that FOXP3 is significantly associated with DFS (HR: 2.55, 95% CI: 1.23-5.30) but is not associated with clinicopathological parameters or OS. We also observed a significant correlation between FOXP3 expression and survival in the estrogen receptor-positive (ER)+ subgroup (HR: 1.83, 95% CI: 1.36-2.47 for DFS, HR: 1.87, 95% CI 1.28-2.73 for OS), in the Asian region (HR: 1.98, 95% CI: 1.56-2.50 for DFS, HR: 1.93, 95% CI: 1.12-3.35 for OS) and using the median as the FOXP3-positive cut-off value (HR: 1.94, 95% CI: 1.57-2.39 for DFS, HR: 2.06; 95% CI: 1.36-3.11 for OS).

CONCLUSION

This meta-analysis indicates that a prognostic role for FOXP3 expression in operable breast cancer cases depends on the FOXP3-positive region, ER status, geographic region and the FOXP3-positive cut-off value.

Cancer-associated fibroblasts as target and tool in cancer therapeutics and diagnostics

Cancer-associated fibroblasts (CAFs) are drivers of tumour progression and are considered as a target and a tool in cancer diagnostic and therapeutic applications. An increased abundance of CAFs or CAF signatures are recognized as a bad prognostic marker in several cancer types. Tumour-environment biomimetics strongly improve our understanding of the communication between CAFs, cancer cells and other host cells. Several experimental drugs targeting CAFs are in clinical trials for multiple tumour entities; alternatively, CAFs can be exploited as a tool to characterize the functionality of circulating tumour cells or to capture them as a tool to prevent metastasis. The continuous interaction between tissue engineers, biomaterial experts and cancer researchers creates the possibility to biomimic the tumour-environment and provides new opportunities in cancer diagnostics and management.