The proportion of tumor-stroma as a strong prognosticator for stage II and III colon cancer patients: validation in the VICTOR trial

Cancer exosomes trigger mesenchymal stem cell differentiation into pro-angiogenic and pro-invasive myofibroblasts

Stromal fibroblasts become altered in response to solid cancers, to exhibit myofibroblastic characteristics, with disease promoting influence. Infiltrating mesenchymal stem cells (MSC) may contribute towards these changes, but the factors secreted by cancer cells that impact MSC differentiation are poorly understood.

We investigated the role of nano-metre sized vesicles (exosomes), secreted by prostate cancer cells, on the differentiation of bone-marrow MSC (BM-MSC), and the subsequent functional consequences of such changes. Purified exosomes impaired classical adipogenic differentiation, skewing differentiation towards alpha-smooth muscle actin (αSMA) positive myofibroblastic cells. A single exosomes treatment generated myofibroblasts secreting high levels of VEGF-A, HGF and matrix regulating factors (MMP-1, −3 and −13). Differentiated MSC had pro-angiogenic functions and enhanced tumour proliferation and invasivity assessed in a 3D co-culture model. Differentiation was dependent on exosomal-TGFβ, but soluble TGFβ at matched dose could not generate the same phenotype. Exosomes present in the cancer cell secretome were the principal factors driving this phenotype.

Prostate cancer exosomes dominantly dictate a programme of MSC differentiation generating myofibroblasts with functional properties consistent with disease promotion.

Quantitative Image Analysis of Epithelial and Stromal Area in Histological Sections of Colorectal Cancer: An Emerging Diagnostic Tool

In colorectal cancer (CRC), an increase in the stromal (S) area with the reduction of the epithelial (E) parts has been suggested as an indication of tumor progression. Therefore, an automated image method capable of discriminating E and S areas would allow an improved diagnosis. Immunofluorescence staining was performed on paraffin-embedded sections from colorectal tumors (16 samples from patients with liver metastasis and 18 without). Noncancerous tumor adjacent mucosa (n = 5) and normal mucosa (n = 4) were taken as controls. Epithelial cells were identified by an anti-keratin 8 (K8) antibody. Large tissue areas (5–63 mm²/slide) including tumor center, tumor front, and adjacent mucosa were scanned using an automated microscopy system (TissueFAXS). With our newly developed algorithms, we showed that there is more K8-immunoreactive E in the tumor center than in tumor adjacent and normal mucosa. Comparing patients with and without metastasis, the E/S ratio decreased by 20% in the tumor center and by 40% at tumor front in metastatic samples. The reduction of E might be due to a more aggressive phenotype in metastasis patients. The novel software allowed a detailed morphometric analysis of cancer tissue compartments as tools for objective quantitative measurements, reduced analysis time, and increased reproducibility of the data.

BACOM2.0 facilitates absolute normalization and quantification of somatic copy number alterations in heterogeneous tumor

Most published copy number datasets on solid tumors were obtained from specimens comprised of mixed cell populations, for which the varying tumor-stroma proportions are unknown or unreported. The inability to correct for signal mixing represents a major limitation on the use of these datasets for subsequent analyses, such as discerning deletion types or detecting driver aberrations. We describe the BACOM2.0 method with enhanced accuracy and functionality to normalize copy number signals, detect deletion types, estimate tumor purity, quantify true copy numbers, and calculate average-ploidy value. While BACOM has been validated and used with promising results, subsequent BACOM analysis of the TCGA ovarian cancer dataset found that the estimated average tumor purity was lower than expected. In this report, we first show that this lowered estimate of tumor purity is the combined result of imprecise signal normalization and parameter estimation. Then, we describe effective allele-specific absolute normalization and quantification methods that can enhance BACOM applications in many biological contexts while in the presence of various confounders. Finally, we discuss the advantages of BACOM in relation to alternative approaches. Here we detail this revised computational approach, BACOM2.0, and validate its performance in real and simulated datasets.

Surveillance for early stages of colon cancer: potentials for optimizing follow-up protocols

Background

Although several meta-analyses showed the positive effects of follow-up on the prognosis of colon cancer (CC), international guidelines are not in accordance on appropriate tests and their time frequency to optimize surveillance. Furthermore, stratified strategies based upon risk grading have not been implemented. This approach may be useful to rationalize resources.

Methods

From 2006, all patients operated for an early stage CC (I, IIA, IIB) according to the 7th edition of the AJCC-2010 classification entered in a prospective surveillance program in accordance to our local guidelines. Patients who underwent surgical resection after 2009 have been excluded to guarantee at least a 5-year follow-up. Classic histopathologic prognostic factors such as grade, T and N status, lymphatic and vascular invasion were assessed. Moreover, tumor budding and tumor-to-stroma proportion were evaluated.

Results

We had complete records of 196 patients. Distribution was as follows: 65 (33.2 %) in stage I, 122 (62.2 %) in stage IIA, and 9 (4.6 %) in stage IIB. Eleven patients (5.6 %) had a disease recurrence (local or distant). The median recurrence time was 20 months (range 6–48). Nine patients (82 %) had recurrence with 24 months, and 91 % were asymptomatic and detected by ultrasound or CT scan. According to the log-rank test, the risk factors with significant effect on the disease-free survival (DFS) were the number of lymph nodes <12 (p = 0.027) and the vascular invasion (p = 0.021), while for the overall (OS), only the vascular invasion was significant (p = 0.043). By the univariate and multivariate analyses, DSF was significantly lower in patients with less than 12 nodes removed, with vascular invasion, and with left of double cancer. OS was negatively affected only by vascular invasion despite the hazard ratios were similar to DSF. Stage IIB was associated with a threefold-increased risk of reduced OS and DSF.

Conclusions

Stages I and IIA appear to behave similarly and should be considered as true early stages. The detection of fibrosis and budding do not seem to add valuable information for prognosis. In early CC stages, the surveillance program should be maximized within the first two years.

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.

Correlation of human papillomavirus status with apparent diffusion coefficient of diffusion-weighted MRI in head and neck squamous cell carcinomas

BACKGROUND

Identification of prognostic patient characteristics in head and neck squamous cell carcinoma (HNSCC) is of great importance. Human papillomavirus (HPV)-positive HNSCCs have favorable response to (chemo)radiotherapy. Apparent diffusion coefficient, derived from diffusion-weighted MRI, has also shown to predict treatment response. The purpose of this study was to evaluate the correlation between HPV status and apparent diffusion coefficient.

METHODS

Seventy-three patients with histologically proven HNSCC were retrospectively analyzed. Mean pretreatment apparent diffusion coefficient was calculated by delineation of total tumor volume on diffusion-weighted MRI. HPV status was analyzed and correlated to apparent diffusion coefficient.

RESULTS

Six HNSCCs were HPV-positive. HPV-positive HNSCC showed significantly lower apparent diffusion coefficient compared to HPV-negative. This correlation was independent of other patient characteristics.

CONCLUSION

In HNSCC, positive HPV status correlates with low mean apparent diffusion coefficient. The favorable prognostic value of low pretreatment apparent diffusion coefficient might be partially attributed to patients with a positive HPV status. © 2015 Wiley Periodicals, Inc. Head Neck 38: E613-E618, 2016.

Cancer-associated fibroblasts in digestive tumors

The significant influence of tumor stroma on malignant cells has been extensively investigated in this era of targeted therapy. The tumor microenvironment, as a dynamic system, is orchestrated by various cells including tumor vascular composing cells, inflammatory cells and fibroblasts. As a major and important component in tumor stroma, increasing evidence has shown that spindle-shaped cancer-associated fibroblasts (CAFs) are a significant modifier of cancer evolution, and promote tumorigenesis, tumor invasion and metastasis by stimulating angiogenesis, malignant cell survival, epithelial-mesenchymal transition (EMT) and proliferation via direct cell-to-cell contact or secretion of soluble factors in most digestive solid tumors. CAFs are thought to be activated, characterized by the expression of α-smooth muscle actin, fibroblast activated protein, fibroblast specific protein, vimentin, fibronectin, etc. They are hypothesized to originate from normal or aged fibroblasts, bone marrow-derived mesenchymal cells, or vascular endothelial cells. EMT may also be an important process generating CAFs, and most probably, CAFs may originate from multiple cells. A close link exists between EMT, tumor stem cells, and chemo-resistance of tumor cells, which is largely orchestrated by CAFs. CAFs significantly induce immunosuppression, and may be a prognostic marker in various malignancies. Targeted therapy toward CAFs has displayed promising anticancer efficacy, which further reinforces the necessity to explore the relationship between CAFs and their hosts.

Evaluation of a tumor microenvironment-based prognostic score in primary operable colorectal cancer

PURPOSE

The tumor microenvironment is recognized as an important determinant of progression and outcome in colorectal cancer. The aim of the present study was to evaluate a novel tumor microenvironment-based prognostic score, based on histopathologic assessment of the tumor inflammatory cell infiltrate and tumor stroma, in patients with primary operable colorectal cancer.

EXPERIMENTAL DESIGN

Using routine pathologic sections, the tumor inflammatory cell infiltrate and stroma were assessed using Klintrup-Mäkinen (KM) grade and tumor stroma percentage (TSP), respectively, in 307 patients who had undergone elective resection for stage I-III colorectal cancer. The clinical utility of a cumulative score based on these characteristics was examined.

RESULTS

On univariate analysis, both weak KM grade and high TSP were associated with reduced survival (HR, 2.42; P = 0.001 and HR, 2.05; P = 0.001, respectively). A cumulative score based on these characteristics, the Glasgow Microenvironment Score (GMS), was associated with survival (HR, 1.93; 95% confidence interval, 1.36-2.73; P < 0.001), independent of TNM stage and venous invasion (both P < 0.05). GMS stratified patients in to three prognostic groups: strong KM (GMS = 0), weak KM/low TSP (GMS = 1), and weak KM/high TSP (GMS = 2), with 5-year survival of 89%, 75%, and 51%, respectively (P < 0.001). Furthermore, GMS in combination with node involvement, venous invasion, and mismatch repair status further stratified 5-year survival (92% to 37%, 93% to 27%, and 100% to 37%, respectively).

CONCLUSIONS

The present study further confirms the clinical utility of assessment of the tumor microenvironment in colorectal cancer and introduces a simple, routinely available prognostic score for the risk stratification of patients with primary operable colorectal cancer.

Colorectal Cancer-Associated Fibroblasts are Genotypically Distinct

Cells in the stromal microenvironment facilitate colorectal cancer (CRC) progression and "co-evolve" with the epithelial cancer cells. Genetic and epigenetic differences between normal colorectal mucosa fibroblasts (NF) and carcinoma-associated fibroblasts (CAF) are not known. The aim of this study is to identify differentially expressed genes and promoter methylation between NF and CAF in human CRC. RNA and DNA were extracted from cultured NF and CAF from CRC resections. Genome-wide gene expression and methylation analyses were performed using the Illumina Human HT-12 v4.0 Expression and Illumina Human Methylation 27 BeadChips. Gene expression values between NF and CAF were compared and correlated with methylation patterns. Data was analyzed using Partek Genomics Suite using one-way ANOVA and p<0.05 as significant. Ingenuity iReport™ was performed to identify potential differences in biological functions and pathways between the NF and CAF. Paired methylation and gene expression analyses from 11 NF and 10 CAF colorectal samples are reported. Unsupervised analysis of differentially expressed genes using iReport™ identified "Top Diseases" as "Cancer" and "Colorectal Cancer". Previous genome wide studies have focused on the cancer cells. We have identified differentially expressed genes and differentially methylated promoter regions that are CAF-specific in CRC.

MicroRNA classifier and nomogram for metastasis prediction in colon cancer

BACKGROUND

Colon cancer prognosis and treatment are currently based on a classification system still showing large heterogeneity in clinical outcome, especially in TNM stages II and III. Prognostic biomarkers for metastasis risk are warranted as development of distant recurrent disease mainly accounts for the high lethality rates of colon cancer. miRNAs have been proposed as potential biomarkers for cancer. Furthermore, a verified standard for normalization of the amount of input material in PCR-based relative quantification of miRNA expression is lacking.

METHODS

A selection of frozen tumor specimens from two independent patient cohorts with TNM stage II-III microsatellite stable primary adenocarcinomas was used for laser capture microdissection. Next-generation sequencing was performed on small RNAs isolated from colorectal tumors from the Dutch cohort (N = 50). Differential expression analysis, comparing in metastasized and nonmetastasized tumors, identified prognostic miRNAs. Validation was performed on colon tumors from the German cohort (N = 43) using quantitative PCR (qPCR).

RESULTS

miR25-3p and miR339-5p were identified and validated as independent prognostic markers and used to construct a multivariate nomogram for metastasis risk prediction. The nomogram showed good probability prediction in validation. In addition, we recommend combination of miR16-5p and miR26a-5p as standard for normalization in qPCR of colon cancer tissue-derived miRNA expression.

CONCLUSIONS

In this international study, we identified and validated a miRNA classifier in primary cancers, and propose a nomogram capable of predicting metastasis risk in microsatellite stable TNM stage II-III colon cancer.

IMPACT

In conjunction with TNM staging, by means of a nomogram, this miRNA classifier may allow for personalized treatment decisions based on individual tumor characteristics.

Accuracy of TNM staging in colorectal cancer: a review of current culprits, the modern role of morphology and stepping-stones for improvements in the molecular era

Colorectal cancer (CRC) is the third most common cancer worldwide. Survival is largely stage-dependant, guided by the tumor-node-metastases (TNM) system for TNM assessment. Histopathological evaluation, including assessment of lymph node status, is important for correct TNM staging. However, recent updates in the TNM system have resulted in controversy. A continued debate on definitions resulting in potential up- and downstaging of patients, which may obscure survival data, has led the investigators to investigate other or alternative staging tools. Consequently, additional prognostic factors have been searched for using the regular light microscopy. Among the factors evaluated by histopathology include the evaluation of tumor budding and stromal environment, angiogenesis, as well as involvement of the immune system (including the 'Immunoscore'). We review the current role of histopathology, controversies in TNM-staging and suggested alternatives to better predict outcome for CRC patients in the era of genomic medicine.

Unsupervised analyses reveal molecular subtypes associated to prognosis and response to therapy in colorectal cancer

SUMMARY

Colorectal cancer (CRC) tumors are highly heterogeneous at a molecular level. Recent studies have proposed molecular classifications of intrinsic CRC molecular subtypes identified after applying unsupervised clustering methods to genome-wide data. Those subtypes, characterized by their distinct clinical and biological features, provide new insight about the complexity of CRC. A common finding shared by almost all analyses was the identification of microsatellite instable tumors as an independent cluster, which is associated to better prognosis. Clusters of tumors characterized by a high stromal component exhibited a poor outcome. Moreover, some of the clusters were associated with response to standard chemotherapy or targeted agents. Regarding biological functions underlying tumor subtypes, recurrent ones across different studies were WNT pathway activation, epithelial-to-mesenchymal transition or cancer stem cell-like phenotype. Now, the challenge is to translate these findings into a comprehensive CRC classification and characterization helpful for patients’ stratification and better clinical management.

The relationship between the tumour stroma percentage, clinicopathological characteristics and outcome in patients with operable ductal breast cancer

Background:

The percentage of tumour stroma (TSP) has recently been reported to be a novel independent predictor of outcome in patients with a variety of common solid organ tumours. The aim of this study was to examine the relationship between TSP, clinicopathological characteristics and outcome in patients with invasive ductal breast cancer, in particular node negative and triple negative disease.

Methods:

A total of 361 patients with primary operable invasive ductal breast cancer were included in this study. The TSP was assessed visually on the haematoxylin and eosin-stained tissue sections. With a cutoff value of 50% TSP, patients with ⩽50% stroma were classified as the low-TSP group and those with >50% stroma were classified as the high-TSP group.

Results:

A total of 109 (30%) patients had high TSP. Patients with high TSP were old age (P=0.035), had more Her-2-positive tumours (P=0.029), low-grade tumour inflammatory infiltrate (P=0.034), low CD68+macrophage infiltrate (P<0.001), low CD4+ (P=0.023) and low CD8+ T-lymphocytes infiltrate (P=0.017), tumour recurrence (P=0.015) and shorter cancer-specific survival (P<0.001). In node-negative patients (n=207), high TSP was associated with low CD68+macrophage infiltrate (P=0.001), low CD4+ (P=0.040) and low CD8+ T-lymphocytes infiltrate (P=0.016) and shorter cancer-specific survival (P=0.005). In triple negative patients (n=151), high TSP was associated with high tumour grade (P=<0.001), lymph node positivity (P=0.027), low CD68+macrophage infiltrate (P=0.011) and shorter cancer-specific survival (P=0.035). The 15-year cancer-specific survival rate was 79% vs 21% in the low-TSP group vs high-TSP group. In multivariate survival analysis, a high TSP was associated with reduced cancer-specific survival in the whole cohort (P=0.001), node-negative patients (P=0.007) and those who received systemic adjuvant therapy (P=0.021), independent of other pathological characteristics including host inflammatory response. However, TSP was not an independent prognostic factor for triple negative patients (P=0.151).

Conclusions:

A high TSP in primary operable invasive ductal breast cancer was associated with recurrence and poorer long-term survival. The inverse relation with the tumour inflammatory infiltrate highlights the importance of the amount of tumour stroma on immunological response in patients with primary operable ductal breast cancer. Implementing this simple and reproducible parameter in routine pathological examination may help optimise risk stratification in patients with invasive ductal breast cancer.

A monotonic and prognostic genomic signature from fibroblasts for colorectal cancer initiation, progression, and metastasis

The differential gene expression patterns between normal colonic fibroblasts (NCF), carcinoma-associated fibroblasts from primary tumors (CAF-PT), and CAFs from hepatic metastasis (CAF-LM) are hypothesized to be useful for predicting relapse in primary tumors. A transcriptomic profile of NCF (n = 9), CAF-PT (n = 14), and CAF-LM (n = 11) was derived. Prediction Analysis of Microarrays (PAM) was used to obtain molecular details for each fibroblast class, and differentially expressed transcripts were used to classify patients according to recurrence status. A number of transcripts (n = 277) were common to all three types of fibroblasts and whose expression level was sequentially deregulated according to the transition: NCF→CAF-PT→CAF-LM. Importantly, the gene signature was able to accurately classify patients with primary tumors according to their prognosis. This capacity was exploited to obtain a refined 19-gene classifier that predicted recurrence with high accuracy in two independent datasets of patients with colorectal cancer and correlates with fibroblast migratory potential. The prognostic power of this genomic signature is strong evidence of the link between the tumor-stroma microenvironment and cancer progression. Furthermore, the 19-gene classifier was able to identify low-risk patients very accurately, which is of particular importance for stage II patients, who would benefit from the omission of chemotherapy, especially T4N0 patients, who are clinically classified as being at high risk.

IMPLICATIONS

A defined stromal gene expression signature predicts relapse in patients with colorectal cancer.

Differences between CAFs and their paired NCF from adjacent colonic mucosa reveal functional heterogeneity of CAFs, providing prognostic information

Little is known about the difference in gene expression between carcinoma-associated fibroblasts (CAFs) and paired normal colonic fibroblasts (NCFs) in colorectal cancer. Paired CAFs and NCFs were isolated from eight primary human colorectal carcinoma specimens. In culture conditions, soluble factors secreted by CAFs in the conditioned media increased clonogenicity and migration of epithelial cancer cells lines to a greater extent than did NCF. In vivo, CAFs were more competent as tumour growth enhancers than paired NCFs when co-inoculated with colorectal cell lines. Gene expression analysis of microarrays of CAF and paired NCF populations enabled us to identify 108 deregulated genes (38 upregulated and 70 downregulated genes). Most of those genes are fibroblast-specific. This has been validated in silico in dataset GSE39396 and by qPCR in selected genes. GSEA analysis revealed a differential transcriptomic profile of CAFs, mainly involving the Wnt signallingsignalling pathway, focal adhesion and cell cycle. Both deregulated genes and biological processes involved depicted a considerable degree of overlap with deregulated genes reported in breast, lung, oesophagus and prostate CAFs. These observations suggest that similar transcriptomic programs may be active in the transition from normal fibroblast in adjacent tissues to CAFs, independently of their anatomic demarcation. Additionally NCF already depicted an activated pattern associated with inflammation. The deregulated genes signature score seemed to correlate with CAF tumour promoter abilities in vitro, suggesting a high degree of heterogeneity between CAFs, and it has also prognostic value in two independent datasets. Further characterization of the roles these biomarkers play in cancer will reveal how CAFs provide cancer cells with a suitable microenvironment and may help in the development of new therapeutic targets for cancer treatment.

Diffusion-weighted MR imaging in laryngeal and hypopharyngeal carcinoma: association between apparent diffusion coefficient and histologic findings

PURPOSE

To investigate the relationship between the histologic characteristics of head and neck squamous cell carcinoma and apparent diffusion coefficient (ADC) at diffusion-weighted magnetic resonance (MR) imaging.

MATERIALS AND METHODS

The institutional ethics committee approved this study and waived informed consent. In head and neck squamous cell carcinoma, local failure after chemotherapy and/or radiation therapy correlates with pretreatment ADC. However, the histopathologic basis of this correlation remains unclear. In this study, 16 patients with head and neck squamous cell carcinoma were enrolled (median age, 60 years; range, 49-78 years). Before undergoing total laryngectomy, patients underwent 1.5-T diffusion-weighted MR imaging. After resection, whole-mount hematoxylin-eosin-stained sections were registered to the MR images. Cellular density; nuclear, cytoplasmic, and stromal area; and nuclear-cytoplasmic ratio within the tumor were calculated by using image-based segmentation on four consecutive slices. Mean ADC of the corresponding tumor region was calculated. Spearman correlations between ADC and histologic characteristics were calculated.

RESULTS

ADC was significantly and inversely correlated with cell density (n = 16, r = -0.57, P = .02), nuclear area (n = 12, r = -0.64, P = .03), and nuclear-cytoplasmic ratio (n = 12, r = -0.77, P ≤ .01). ADC was significantly and positively correlated with percentage area of stroma (n = 12, r = 0.69, P = .01). Additionally, the percentage area of stroma was strongly interdependent with the percentage area of nuclei (n = 12, r = -0.97, P ≤ .01).

CONCLUSION

ADC was significantly correlated with cellularity, stromal component, and nuclear-cytoplasmic ratio. The positive correlation of ADC and stromal component suggests that the poor prognostic value of high pretreatment ADC might partly be attributed to the tumor-stroma component, a known predictor of local failure.

The relationship between tumour stroma percentage, the tumour microenvironment and survival in patients with primary operable colorectal cancer

BACKGROUND

Tumour stroma percentage (TSP) has previously been reported to predict survival in patients with colorectal cancer (CRC); however, whether this is independent of other aspects of the tumour microenvironment is unknown. In the present study, the relationship between TSP, the tumour microenvironment and survival was examined in patients undergoing elective, curative CRC resection.

PATIENTS AND METHODS

Patients undergoing resection at a single centre (1997-2008) were identified from a prospective database. TSP was measured at the invasive margin and its association with cancer-specific survival (CSS) and clinicopathological characteristics examined.

RESULTS

Three hundred and thirty-one patients were included in the analysis. TSP was associated with CSS in patients with stage I-III disease [hazard ratio (HR) 1.84, 95% confidence interval (CI) 1.17-2.92, P = 0.009], independent of age, systemic inflammation, N stage, venous invasion and Klintrup-Mäkinen score. Furthermore, TSP was associated with reduced CSS in patients with node-negative disease (HR 2.14, 95% CI 1.01-4.54, P = 0.048) and those who received adjuvant chemotherapy (HR 2.83, 95% CI 1.23-6.53, P = 0.015), independent of venous invasion and host inflammatory responses. TSP was associated with several adverse pathological characteristics, including advanced T and N stage. Furthermore, TSP was associated with an infiltrative invasive margin and inversely associated with necrosis.

CONCLUSIONS

The TSP was a significant predictor of survival in patients undergoing elective, curative CRC resection, independent of adverse pathological characteristics and host inflammatory responses. In addition, TSP was strongly associated with local tumour growth and invasion.

Prognostic relevance of cancer-associated fibroblasts in human cancer

Prognostication is an integral part of cancer diagnostic and helps oncologists to guide treatment decisions and therapy intensity. Accumulating evidence suggest that the stroma compartment also contains independent prognostic information, best exemplified by the impact of immune cells and cells of the vasculature on cancer progression. Similarly, strong experimental evidence exist that stromal fibroblasts, often designated cancer associated fibroblasts (CAFs), are actively involved in tumorigenesis. Thus, it can be anticipated that the molecular repertoire of CAFs is likewise important for the clinical behavior of the tumor. In this review we present recent studies addressing the prognostic impact of CAFs, with the focus on human lung and breast cancer. Several single markers have been suggested, either CAF specific or CAF derived, that in immunohistochemical studies have demonstrated independent association with survival. This includes members of the platelet derived growth factor receptor (PDGFR) family, CAF-markers like podoplanin and fibroblast activation protein (FAP) as well as transcription factors (FoxF1) and secreted factors (matrix metalloproteinases (MMPs), SPARC). However, most studies are based on explorative evaluations on single patient cohorts and require further validation. Using a more comprehensive approach, microarray studies have been employed to create gene expression signatures that detect an activated fibroblast state. These "stroma signatures" have been applied to identify specific CAF features associated with prognosis in several independent data sets of breast and lung cancer patients. Early studies in breast cancer have also demonstrated that fibroblast features influence therapy response. Thus, many strategies have been used to present encouraging proof-of-concept findings that CAFs could be exploited for prognostication. However, these studies also highlight the difficulties to conclusively define an "activated stroma" and to identify the individual factors involved in clinically relevant tumor-stroma interactions.

Carcinoma-associated fibroblasts provide operational flexibility in metastasis

Malignant cancer cells do not act as lone wolves to achieve metastasis, as they exist within a complex ecosystem consisting of an extracellular matrix scaffold populated by carcinoma-associated fibroblasts (CAFs), endothelial cells and immune cells. We recognize local (primary tumor) and distant ecosystems (metastasis). CAFs, also termed myofibroblasts, may have other functions in the primary tumor versus the metastasis. Cellular origin and tumor heterogeneity lead to the expression of specific markers. The molecular characteristics of a CAF remain in evolution since CAFs show operational flexibility. CAFs respond dynamically to a cancer cell's fluctuating demands by shifting profitable signals necessary in metastasis. Local, tissue-resident fibroblasts and mesenchymal stem cells (MSCs) coming from reservoir sites such as bone marrow and adipose tissue are the main progenitor cells of CAFs. CAFs may induce awakening from metastatic dormancy, a major cause of cancer-specific death. Cancer management protocols influence CAF precursor recruitment and CAF activation. Since CAF signatures represent early changes in metastasis, including formation of pre-metastatic niches, we discuss whether liquid biopsies, including exosomes, may detect and monitor CAF reactions allowing optimized prognosis of cancer patients.