The role of myofibroblasts at the tumor border of invasive colorectal adenocarcinomas

Pathology and Prognosis of Colonic Adenocarcinomas With Intermediate Primary Tumor Stage Between pT2 and pT3

CONTEXT.—

Primary tumor stage (pT) is an important prognostic indicator in colonic adenocarcinomas; however, cases that have no muscle fibers beyond the advancing tumor edge but also show no extension beyond the apparent outer border of muscularis propria (termed pT2int), have not been previously studied.

OBJECTIVE.—

To address the clinicopathologic characteristics and prognosis of pT2int tumors.

DESIGN.—

We recharacterized 168 colon carcinomas and compared pT2int cases to bona fide pT2 and pT3 tumors.

RESULTS.—

In side-by-side analysis, 21 pT2int cases diverged from 29 pT2 tumors only in terms of larger size (P = .03), but they were less likely to show high-grade (P = .03), lymphovascular (P < .001), and extramural venous invasion (P = .04); discontinuous tumor deposits (P = .02); lymph node involvement (P = .001); and advanced stage (P = .001), compared with 118 pT3 tumors. Combining pT2int with pT2 cases (versus pT3) was a better independent predictor of negative lymph nodes in multivariate analysis (P = .04; odds ratio [OR], 3.96; CI, 1.09-14.42) and absent distant metastasis in univariate analysis (P = .04), compared with sorting pT2int with pT3 cases (versus pT2). Proportional hazards regression showed that pT2 and pT2int cases together were associated with better disease-free survival compared with pT3 tumors (P = .04; OR, 3.65; CI, 1.05-12.70). Kaplan-Meier analysis demonstrated that when pT2int were grouped with pT2 tumors, they were significantly less likely to show disease progression compared with pT3 (P = .002; log-rank test) and showed a trend toward better disease-specific survival (P = .06), during a mean patient follow-up of 44.9 months.

CONCLUSIONS.—

These data support the conclusion that pT2int carcinomas have clinicopathologic characteristics and are associated with patient outcomes more closely aligned with pT2 rather than pT3 tumors.

Exosomes Derived from the Human Primary Colorectal Cancer Cell Line SW480 Orchestrate Fibroblast-Led Cancer Invasion

In localized tumors, basement membrane (BM) prevents invasive outgrowth of tumor cells into surrounding tissues. When carcinomas become invasive, cancer cells either degrade BM or reprogram stromal fibroblasts to breach BM barrier and lead invasion of cancer cells into surrounding tissues in a process called fibroblast-led invasion. However, tumor-derived factors orchestrating fibroblast-led invasion remain poorly understood. Here it is shown that although early-stage primary colorectal adenocarcinoma (SW480) cells are themselves unable to invade Matrigel matrix, they secrete exosomes that reprogram normal fibroblasts to acquire de novo capacity to invade matrix and lead invasion of SW480 cells. Strikingly, cancer cells follow leading fibroblasts as collective epithelial-clusters, thereby circumventing need for epithelial to mesenchymal transition, a key event associated with invasion. Moreover, acquisition of pro-invasive phenotype by fibroblasts treated with SW480-derived exosomes relied on exosome-mediated MAPK pathway activation. Mass spectrometry-based protein profiling reveals that cancer exosomes upregulate fibroblasts proteins implicated in focal adhesion (ITGA2/A6/AV, ITGB1/B4/B5, EGFR, CRK), regulators of actin cytoskeleton (RAC1, ARF1, ARPC3, CYFIP1, NCKAP1, ICAM1, ERM complex), and signalling pathways (MAPK, Rap1, RAC1, Ras) important in pro-invasive remodeling of extracellular matrix. Blocking tumor exosome-mediated signaling to fibroblasts therefore represents an attractive therapeutic strategy in restraining tumors by perturbing stroma-driven invasive outgrowth.

Integrin α5 subunit is required for the tumor supportive role of fibroblasts in colorectal adenocarcinoma and serves as a potential stroma prognostic marker

The tumorigenesis of colorectal cancer (CRC) is a complicated process, involving interactions between cancer cells and the microenvironment. The role of α5 integrin subunit in CRC remains controversial, and previous studies mainly focused on cancer cells. Herein, we report an important role of α5 in stroma fibroblasts in the tumorigenesis of CRC. The expression of α5 was found to be located in colorectal tumor stroma rather than in epithelia cancer cells. Immunofluorescence colocalization and gene correlation analysis confirmed that α5 was mainly expressed in cancer-associated fibroblasts (CAFs). Moreover, experimental evidence showed that α5 expression was required for the tumor-promoting effect of fibroblast cells. In an in vivo xenograft nude mice model, α5 depletion in fibroblasts dramatically suppressed fibroblast-induced tumor growth. In an in vitro cell coculture assay, α5 depletion or knockdown reduced the ability of fibroblasts to promote cancer cell migration and invasion compared with wild-type fibroblasts; moreover, we observed that the expression and assembly of fibronectin were downregulated after α5 depletion or knockdown in fibroblasts. Analysis of the RNA-Seq data of the Cancer Genome Atlas cohort revealed that high expression of ITGA5 (α5 integrin subunit) was correlated with poor overall survival in colorectal adenocarcinoma, which was further confirmed by immunohistochemistry in an independent cohort of 355 patients. Thus, our study identifies α5 integrin subunit as a novel stroma molecular marker for colorectal adenocarcinoma, offers a fresh insight into colorectal adenocarcinoma progression, and shows that α5 expression in stroma fibroblasts underlies its ability to promote the tumorigenesis of colorectal adenocarcinoma.

An Immunohistochemical and Polarizing Microscopic Study of the Tumor Microenvironment in Varying Grades of Oral Squamous Cell Carcinoma

BACKGROUND

Invasion of epithelial cells into the connective tissue brings about massive morphological and architectural changes in the underlying stroma. Myofibroblasts reorganize the stroma to facilitate the movement of tumor cells leading to metastasis. The aim of this study was to determine the number and pattern of distribution of myofibroblasts and the qualitative and quantitative change that they cause in the collagen present in the stroma in various grades of oral squamous cell carcinoma (OSCC).

METHODS

The study was divided into two groups with group I (test group, 65 cases) consisting of 29 cases of well-differentiated squamous cell carcinoma, 25 moderately differentiated SCC, and 11 poorly differentiated SCC, and group II (control group) consisting of 11 cases of normal mucosa. Sections from each sample were stained with anti-α-smooth muscle actin (α-SMA) antibodies, hematoxylin and eosin, and Picrosirius red. Several additional sections from each grade of OSCC were stained with Masson's trichrome to observe the changes in collagen. For the statistical analysis, Fisher's exact test, Tukey's post hoc honest significant difference test, ANOVA, and the chi-square test were used, and p < .05 was considered statistically significant.

RESULTS

As the tumor stage progressed, an increase in the intensity α-SMA expression was seen, and the network pattern dominated in more dedifferentiated carcinomas. The collagen fibers became thin, loosely packed, and haphazardly aligned with progressing cancer. Additionally, the mean area fraction decreased, and the fibers attained a greenish yellow hue and a weak birefringence when observed using polarizing light microscopy.

CONCLUSIONS

Myofibroblasts bring about numerous changes in collagen. As cancer progresses, there isincrease in pathological collagen,which enhances the movement of cells within the stroma.

Microenvironmental Signals and Biochemical Information Processing: Cooperative Determinants of Intratumoral Plasticity and Heterogeneity

Intra-tumor cellular heterogeneity is a major challenge in cancer therapy. Tumors are composed of multiple phenotypic subpopulations that vary in their ability to initiate metastatic tumors and in their sensitivity to chemotherapy. In many cases, cells can transition between these subpopulations, not by genetic mutation, but instead through reversible changes in signal transduction or gene expression programs. This plasticity begins at the level of the microenvironment where local autocrine and paracrine signals, exosomes, tumor–stroma interactions, and extracellular matrix (ECM) composition create a signaling landscape that varies over space and time. The integration of this complex array of signals engages signaling pathways that control gene expression. The resulting modulation of gene expression programs causes individual cells to sample a wide array of phenotypic states that support tumor growth, dissemination, and therapeutic resistance. In this review, we discuss how information flows dynamically within the microenvironmental landscape to inform cell state decisions and to create intra-tumoral heterogeneity. We address the role of plasticity in the acquisition of transient and prolonged drug resistant states and discuss how targeted pharmacological modification of the signaling landscape may be able to constrain phenotypic plasticity, leading to improved treatment responses.

Ki67, CD105, and α-SMA expressions better relate the binary oral epithelial dysplasia grading system of World Health Organization

BACKGROUND

The binary system of oral epithelial dysplasia (OED) has never been investigated with reference to the carcinogenesis-related biomarkers. Hence, Ki67, CD105, and α-SMA immune-expressions were studied in oral potentially malignant disorders (OPMDs) to assess their relationship with the binary OED grading system of World Health Organization.

METHODS

The study was carried out on paraffin-embedded tissues of 30 normal oral mucosa (NOM) and 140 OPMD cases. OPMD cases were classified into two groups "no/questionable/hyperkeratosis/mild"=low-risk epithelial dysplasia (LRED) and "moderate or severe"=high-risk epithelial dysplasia (HRED). The immunohistochemistry was carried out to evaluate the expression of Ki67, CD 105, and α-SMA antigen.

RESULTS

According to the binary grading system of WHO, 69 (49.28%) cases were LRED, while 71 (50.71%) case showed HRED. There was significant increase in Ki67 labeling index (LI) from NOM to LRED to HRED (P=.000). Similarly, mean vascular density (MVD) also increased significantly from NOM to LRED to HRED (P=.000). The α-SMA expression was significantly higher in HERD compared to LRED and NOM (P=.000). A positive correlation was noted among Ki67 LI, MVD, and α-SMA expressions in NOM, LRED, and HRED (P=.000).

CONCLUSION

The expressions of ki67, CD105, and α-SMA markers compliment binary grading system of OED in OPMDS, thus justifying its use in clinical practice.

EMT, CSCs, and drug resistance: the mechanistic link and clinical implications

The success of anticancer therapy is usually limited by the development of drug resistance. Such acquired resistance is driven, in part, by intratumoural heterogeneity - that is, the phenotypic diversity of cancer cells co-inhabiting a single tumour mass. The introduction of the cancer stem cell (CSC) concept, which posits the presence of minor subpopulations of CSCs that are uniquely capable of seeding new tumours, has provided a framework for understanding one dimension of intratumoural heterogeneity. This concept, taken together with the identification of the epithelial-to-mesenchymal transition (EMT) programme as a critical regulator of the CSC phenotype, offers an opportunity to investigate the nature of intratumoural heterogeneity and a possible mechanistic basis for anticancer drug resistance. In fact, accumulating evidence indicates that conventional therapies often fail to eradicate carcinoma cells that have entered the CSC state via activation of the EMT programme, thereby permitting CSC-mediated clinical relapse. In this Review, we summarize our current understanding of the link between the EMT programme and the CSC state, and also discuss how this knowledge can contribute to improvements in clinical practice.

Myofibroblast distribution is associated with invasive growth types of colorectal cancer

Both the invasive growth types of colorectal cancer (CRC) and the number of myofibroblasts have been associated with histopathological factors such as lymph node and liver metastasis, and local recurrence. However, there are few studies, that have assessed the association between invasive growth type and myofibroblast distribution in CRC. We aimed to evaluate the relationship between the clinicopathological factors of CRC and two invasive growth types, the expanding and infiltrating types. We categorized 150 cases of pT3 CRC into the expanding and infiltrating types and measured the myofibroblast density of three histological layers: the submucosa (SM), the muscularis propria (MP) and the subserosa (SS). We compared these two invasive growth types and analyzed the relationship between clinicopathological factors and myofibroblast density. Myofibroblast density was significantly higher in the infiltrating type than that in the expanding type (P<0.05). In the lymph node metastasis-positive group of the infiltrating type, myofibroblast density in MP was significantly higher than that in the lymph node metastasis-negative group (P<0.001). In the infiltrating type, the group with the higher level of lymphatic invasion had a significantly higher density of myofibroblasts in the MP than the group with the lower level of lymphatic invasion (P<0.01). These results suggest that myofibroblasts participate more in the infiltrating type compared with the expanding type of CRC. It would appear that myofibroblasts present in the MP play an important role in the malignant potential of the infiltrating type compared to the expanding type.

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.

Myofibroblasts of the muscle layer stimulate the malignant potential of colorectal cancer

Myofibroblasts of colorectal cancer (CRC) have been associated with histopathological factors such as lymph node metastasis, liver metastasis and local recurrence. However, few studies have assessed the association between these malignant potentials and the myofibroblast distribution in CRC. We aimed to evaluate the relationship between clinical factors and myofibroblast distribution around CRC invasive lesions. The study included 121 cases of pT3 CRC that were diagnosed at stage II or III. Myofibroblast density of the following three histological layers was measured: the submucosa (SM), muscularis propria (MP) and subserosa (SS). We analyzed the relationship between the clinicopathological factors and myofibroblast density by studying the histopathological features of the three layers. The myofibroblast density of the MP layer was significantly higher in the groups with high-frequency lymphatic and venous invasion than the groups with low-frequency lymphatic (P<0.001) and venous (P<0.01) invasion, respectively. In the positive lymph node metastasis group, the myofibroblast density at the MP layer was significantly higher than that in the negative lymph node metastasis group (P<0.001). The high myofibroblast density group at the MP layer was significantly associated with poor overall survival (P<0.003). Our study indicated that myofibroblasts are a type of cancer-associated fibroblasts and that the myofibroblast distribution contributes to the malignant potential of CRC. Furthermore, we demonstrated that myofibroblasts present at the MP layer play an important role in the malignant potential and poor prognosis of patients with CRC.

Cancer-associated fibroblasts provide a suitable microenvironment for tumor development and progression in oral tongue squamous cancer

Background

Oral tongue squamous cell carcinoma (OTSCC) is still associated with a poor prognosis due to local recurrence and metastasis. Cancer-associated fibroblasts (CAFs) play an important role in the complex processes of cancer stroma interaction and tumorigenesis. This study aims to determine the role of CAFs in the development and progression of OTSCC.

Methods

Immunohistochemistry was performed to evaluate the frequency and distribution of CAFs in 178 paraffin specimens from patients with OTSCC. Immunofluorescence, a cell proliferation assay, flow cytometry, migration and invasion assays and western blot analysis were used to study the effects of CAFs and the corresponding conditioned medium (CM) on the proliferation and invasion of OTSCC cell lines.

Results

Statistical analysis showed a strong correlation between the frequency and distribution of CAFs and the clinicopathological characteristics of patients with cN0 OTSCC, including pathological stage (P = 0.001), T classification (P = 0.001), and N classification (P = 0.009). Survival analysis demonstrated a negative correlation of the frequency and distribution of CAFs with the overall survival and disease-free survival of patients with cN0 tongue squamous cell cancer (P = 0.009, 0.002, respectively); Cox regression analysis showed that the presence of CAFs (relative risk: 2.113, CI 1.461–3.015, P = 0.023) is an independent prognostic factor. A functional study demonstrated that CAFs and CM from CAFs could promote the growth, proliferation, mobility, invasion and even Epithelial Mesenchymal Transition (EMT) of OTSCC cells compared with NFs and CM from NFs.

Conclusions

CAFs were an independent prognostic factor for patients with OTSCC. Compared with NFs, CAFs and their CM have the ability to promote the growth, proliferation, metastasis and even EMT of OTSCC cells.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-015-0551-8) contains supplementary material, which is available to authorized users.

Histological assessment of intra- and inter-institutional reliabilities in detection of desmoplastic reaction in biopsy specimens of early colorectal carcinomas

We previously reported a relationship between depth of submucosal invasion of early colorectal carcinomas and desmoplastic reaction (DR). However, poor inter-observer agreement on the histopathological diagnosis of DR in biopsy specimens with hematoxylin and eosin (H&E) staining has been the major critique of this tool. In this study, reproducibility of the histopathological diagnosis of DR was evaluated. Furthermore, we investigated the possible improvement of the reproducibility after education about histological characteristics and tried to identify histological characteristics that are most important in the recognition of DR. A total of 34 H&E stained slides were included in this study and analyzed by three pathologists. Slides were reviewed before and after education about histological characteristics of DR. Kappa statistics were used to compare the inter-observer variability. We investigated the relationship between DR and histopathological factor. The inter-observer agreement during the first session varied between 0.30 and 0.63, which improved during the second session toward an agreement between 0.58 and 0.71. Myofibroblast proliferation associated with cancer invasion was found to be the most useful in the diagnosis of DR. In conclusion, the correct detection of myofibroblasts may facilitate the standardization of diagnosis of DR.

Podoplanin, α-smooth muscle actin or S100A4 expressing cancer-associated fibroblasts are associated with different prognosis in colorectal cancers

The interactions between the tumor microenvironment and tumor cells determine the behavior of the primary tumors. Whether cancer-associated fibroblasts (CAF) have a tumor progressive or a protective role likely depends on the type of tumor cells and the CAF subpopulation. In the present study, we analyzed the prognostic significance of CAF subpopulations in colorectal cancer (CRC). CAF phenotypes were analyzed in 302 CRC patients by using antibodies against podoplanin (PDPN), α-smooth muscle actin (α-SMA), and S100A4. The relationship between the CAF phenotypes and 11 clinicopathological parameters were evaluated and their prognostic significance was analyzed from the disease-free and overall survival times. We observed that at the tumor invasive front, PDPN CAFs were present in 40% of the cases, and S100A4 or α-SMA CAFs were detected in all the cases. PDPN/S100A4 and α-SMA/S100A4 dual-stained CAFs were observed in 10% and 40% of the cases, respectively. The PDPN(+) CAFs were associated with 6 favorable clinicopathological parameters and prolonged disease-free survival time. The PDPN(-)/α-SMA(high) CAFs were associated with 6 aggressive clinicopathological parameters and tended to exhibit shorter disease-free survival time. On the other hand, the PDPN(-)/S100A4(high) CAFs were associated with 2 tumor progression parameters, but not with disease prognosis. The PDPN(+) CAF phenotype is distinct from the α-SMA or S100A4 CAFs in that it is associated with less aggressive tumors and a favorable prognosis, whereas the PDPN(-)/α-SMA(high) or PDPN(-)/S100A4(high) CAFs are associated with tumor progression in CRC. These findings suggest that CAFs can be a useful prognostic biomarker or potential targets of anti-cancer therapy in CRC.

Expression of podoplanin/D2-40 in pericryptal stromal cells in superficial colorectal epithelial neoplasia

The aim of this study is to investigate the distribution and roles of podoplanin/D2-40-positive pericryptal stromal cells in superficial colorectal epithelial neoplasia. A total of 105 superficial colorectal epithelial tumors were examined: 65 tubular/tubulovillous adenomas, 32 adenocarcinomas in situ, and 8 submucosally invasive adenocarcinomas. Immunohistochemical analysis was performed using the monoclonal antibody to podoplanin/clone D2-40, which is reactive in both lymphatic endothelial cells and activated stromal cells, but negative in vascular endothelial cells. We found 50 (78 %) of 65 tubular/tubulovillous adenomas, 30 (94 %) of 32 adenocarcinomas in situ, and all 8 (100 %) submucosally invasive adenocarcinomas had podoplanin/D2-40-positive pericryptal stromal cells, whereas all normal colorectal mucosae had no podoplanin/D2-40-positive pericryptal stromal cells. The presence of podoplanin/D2-40-positive pericryptal stromal cells is associated with epithelial tumorigenesis in the colorectum.

Comparison of myofibroblasts expression in oral squamous cell carcinoma, verrucous carcinoma, high risk epithelial dysplasia, low risk epithelial dysplasia and normal oral mucosa

The aim was to evaluate and compare the presence of myofibroblasts in oral squamous cell carcinoma (OSCC), verrucous carcinoma (VC), high-risk epithelial dysplasia (HRED), low-risk epithelial dysplasia (LRED), and normal oral mucosa (NOM). The study consisted of 37 OSCC, 15 VC, 15 HRED, 15 LRED and 15 NOM. α-smooth muscle actin (α-SMA) antibody was used to identify myofibroblasts. The α-SMA expression was not observed in NOM and LRED. The α-SMA was expressed in 97.29% of OSCC, 86.66% of VC, 46.66 % of HRED. The α-SMA expression was significantly higher in OSCC than VC (p = 0.023) and HRED (p < 0.000). The α-SMA expression was significantly higher in VC than HRED (p = 0.043). Myofibroblastic expression, as highlighted by α-SMA, is undetectable in NOM and LRED but increases as the disease progresses from potentially malignant disorders, as HRED to VC to invasive OSCC. Thus, proliferation of myofibroblasts may be used as a stromal marker of oral premalignancy and malignancy.

Cancer-associated fibroblasts and CD163-positive macrophages in oral squamous cell carcinoma: their clinicopathological and prognostic significance

BACKGROUND

Stromal cells are believed to affect cancer invasion and metastasis. The purpose of this study was to evaluate the distribution of cancer-associated fibroblasts (CAFs) and the incidence of tumor-associated macrophages (TAMs) in oral squamous cell carcinoma (OSCC), focusing on clinicopathological factors and patient prognosis, as well as cancer invasion.

METHODS

The study included 108 patients with OSCC. Anti-α-smooth muscle actin, CD68, and CD163 antibodies were used to identify CAFs and TAMs. CAFs were divided into 4 grades on the basis of staining intensity: negative (0), scanty (1), focal (2), and abundant (3). The most intensive areas of macrophage concentration in each tumor invasive stroma were also evaluated.

RESULTS

The cancer specimens were divided into Grade 0/1, Grade 2, and Grade 3 on the basis of CAF grade. In addition, they were divided into low- and high-grade groups on the basis of the number of CD68-positive and CD163-positive macrophages. The latter were significantly increased in the Grade 2 CAF group compared to the Grade 0/1 group (P = 0.009). Kaplan-Meier and multivariate survival analyses revealed that Grade 2 CAFs (P = 0.003) and high CD163-positive macrophage levels (P = 0.007) significantly correlated with a poor outcome in patients with OSCC, and that a high CD163-positive macrophage level was a significant and an independent prognostic factor (P = 0.045).

CONCLUSIONS

Cancer-associated fibroblasts and CD163-positive macrophages may be potential prognostic predictors of OSCC.

Colorectal cancer cells activate adjacent fibroblasts resulting in FGF1/FGFR3 signaling and increased invasion

Cancer-associated fibroblasts expressing fibroblast activation protein (FAP) have been implicated in the invasive behavior of colorectal cancer. In this study, we use FAP expression as a marker of fibroblast activation and analyze the effect of activated fibroblasts on colorectal cancer migration and invasion in experimental cell studies. We also investigated the expression pattern of FAP in cancer-associated fibroblasts during transformation from benign to malignant colorectal tumors. In immunohistochemical analyses, FAP was expressed in fibroblasts in all colorectal cancer samples examined, whereas all normal colon, hyperplastic polyps, or adenoma samples were negative. In in vitro studies, conditioned medium from colon cancer cells, but not adenoma cells, activated fibroblasts by inducing FAP expression. These activated fibroblasts increased the migration and invasion of colon cancer cells in Boyden chamber experiments and in a three-dimensional cell culture model. We identify fibroblast growth factor 1/fibroblast growth factor receptor 3 (FGF1/FGFR-3) signaling as mediators leading to the increased migration and invasion. Activated fibroblasts increase their expression of FGF1, and by adding a fibroblast growth factor receptor inhibitor, as well as an FGF1-neutralizing antibody, we reduced the migration of colon cancer cells. Our findings provide evidence of a possible molecular mechanism involved in the cross talk between cancer cells and fibroblasts leading to cancer cell invasion.

Fibroblast growth factor receptor 2-positive fibroblasts provide a suitable microenvironment for tumor development and progression in esophageal carcinoma

PURPOSE

Tumor fibroblasts (TF) have been suggested to play an essential role in the complex process of tumor-stroma interactions and tumorigenesis. The aim of the present study was to investigate the specific role of TF in the esophageal cancer microenvironment.

EXPERIMENTAL DESIGN

An Affymetrix expression microarray was used to compare gene expression profiles between six pairs of TFs and normal fibroblasts from esophageal squamous cell carcinoma (ESCC). Differentially expressed genes were identified, and a subset was evaluated by quantitative real-time PCR and immunohistochemistry.

RESULTS

About 43% (126 of 292) of known deregulated genes in TFs were associated with cell proliferation, extracellular matrix remodeling, and immune response. Up-regulation of fibroblast growth factor receptor 2 (FGFR2), which showed the most significant change, was detected in all six tested TFs compared with their paired normal fibroblasts. A further study found that FGFR2-positive fibroblasts were only observed inside the tumor tissues and not in tumor-surrounding stromal tissues, suggesting that FGFR2 could be used as a TF-specific marker in ESCC. Moreover, the conditioned medium from TFs was found to be able to promote ESCC tumor cell growth, migration, and invasion in vitro.

CONCLUSIONS

Our study provides new candidate genes for the esophageal cancer microenvironment. Based on our results, we hypothesize that FGFR2(+)-TFs might provide cancer cells with a suitable microenvironment via secretion of proteins that could promote cancer development and progression through stimulation of cancer cell proliferation, induction of angiogenesis, inhibition of cell adhesion, enhancement of cell mobility, and promotion of the epithelial-mesenchymal transition.

Active TGF-beta1 correlates with myofibroblasts and malignancy in the colorectal adenoma-carcinoma sequence

Transforming growth factor-beta1 (TGF-beta1), a cytokine involved in various stages of cancer, is produced as a latent complex and requires processing to become active. We have determined total and active TGF-beta1 levels in homogenates of colorectal neoplasia. In contrast to total TGF-b levels, showing a stepwise increase in the mucosa-adenoma-carcinoma sequence, active TGF-beta1 levels are increased only in carcinomas but not in premalignant adenomas. Furthermore, solely active TGF-beta1 levels are associated with the stage of the carcinomas and worse patient prognosis. Active TGF-beta1 levels correlated significantly with plasminogen activator inhibitor (PAI)-1, alpha-smooth muscle actin (SMA) and several matrix-remodeling proteinases. Interestingly, SMA levels are also significantly increased in colorectal carcinomas but not in adenomas, suggesting that despite the enhanced total TGF-beta1 levels, myofibroblast accumulation is not (yet) occurring in these premalignant neoplasias. The correlation between active TGF-beta1 and SMA expression in tumors indicates that tumor-promoting myofibroblasts might arise as a result of increased TGF-beta1 activation. These data underline the significance of the interaction between malignant cells and (myo)-fibroblasts in the tumor microenvironment, modulating the biologic behavior of colorectal cancer.

The essential role of fibroblasts in esophageal squamous cell carcinoma-induced angiogenesis

BACKGROUND & AIMS

Esophageal squamous cell carcinoma (ESCC) is known to be a highly angiogenic tumor. Here, we investigated the role of the stromal fibroblasts in the ESCC-induced angiogenic response using a novel 3-dimensional model.

METHODS

A novel assay was developed where cocultures of ESCC and esophageal fibroblasts induced human microvascular endothelial cell (HMVEC) vascular network formation in a 3-dimensional collagen gel. Biochemical studies showed that the ESCC-induced activation of the fibroblasts was required to induce vascular network formation via a transforming growth factor (TGF)-beta and vascular endothelial growth factor (VEGF)-dependent pathway.

RESULTS

Conditioned media from a panel of 4 ESCC lines transdifferentiated normal esophageal fibroblasts into myofibroblasts via TGF-beta signaling. The presence of fibroblasts was essential for efficient HMVEC network formation, and the addition of ESCC cells to these cultures greatly enhanced the angiogenic process. The role of TGF-beta in this process was shown by the complete inhibition of network formation following TGF-beta inhibitor treatment. Finally, we showed that ESCC-derived TGF-beta regulates angiogenesis through the release of VEGF from the fibroblasts and that the VEGF release was blocked following TGF-beta inhibition.

CONCLUSIONS

This study shows the essential role of fibroblasts in the ESCC angiogenic-induced response and suggests that the pharmacologic targeting of the TGF-beta signaling axis could be of therapeutic benefit in this deadly disease.

Desmoplasia in different degrees of invasion of carcinoma ex-pleomorphic adenoma

Stroma desmoplasia was studied by immunohistochemistry for alpha-smooth muscle actin (alpha-SMA) in 17 instances of carcinoma ex-pleomorphic adenoma (CXPA) classified according to the presence of epithelial and myoepithelial cells and the degree of invasion: intracapsular, minimally and frankly invasive carcinoma. In "resident" pleomorphic adenoma, no desmoplasia was detected. In invasive areas of the intracapsular type of CXPA with only an epithelial component, desmoplasia started to be revealed by the presence of myofibroblasts close to the capsule. In the minimally invasive type, myofibroblasts were seen in the septum between islands of malignant cells and in focal peripheral areas of the tumor interpreted as the actual front of invasion. In the frankly invasive type of CXPA showing large blocks of cells, intense desmoplasia was seen, also separating the tumor cells from the neighboring normal tissue. In tumors with cords and/or small nests of cells, desmoplasia was very slight. In the invasive type of CXPA with a myoepithelial component, alpha-SMA expression was seen in the septum between the islands of cells. The expression was less intense and not present in all areas of the stroma. In CXPA with epithelial and myoepithelial cells, myofibroblasts were rarely seen in the septum separating sheets of cells. Thus, we may deduce that the presence of desmoplasia parallels the capacity of invasion of CXPA by epithelial cells, being minimum in the intracapsular and minimally invasive type of CXPA and increasing as the tumor becomes frankly invasive. Furthermore, we may also conclude that in CXPA with a myoepithelial component, desmoplasia is very rare.

CAM5.2-positive subserosal myofibroblasts in appendicitis

In this study, we examined the distribution and origin of myofibroblasts around the perforations of appendicitis. Stromal cells of 45 cases were studied by immunohistochemistry. In the normal appendix, myofibroblasts were restricted to the mucosa, and CD34-positive stromal cells were distributed in the submucosal and subserosal layers. Some mesothelial cells were positive for cytokeratin CAM5.2, cytokeratin 5, or mesothelial cells (HBME-1). In perforation of appendicitis with both abscess and granulation tissue, a small to moderate or a moderate to large number of myofibroblasts appeared in the subserosal area around the perforation, respectively, but CD34-positive stromal cells were completely absent there. In the subserosal area of the perforation of appendicitis with abscess, cytokeratin 5-positive stromal cells were absent. However, a small to moderate number of cytokeratin CAM5.2-positive stromal cells were observed there. Double immunostaining showed the coexpression of alpha-smooth muscle actin (ASMA) and cytokeratin CAM5.2 and the coexpression of cytokeratin 5 and cytokeratin CAM5.2 in many or some stellate-shaped or spindle-shaped stromal cells existing in the subserosal area with granulation tissue around the perforation of appendicitis, respectively. Finally, many myofibroblasts appearing in the subserosal area of the perforation of appendicitis may be derived from submesothelial cells or mesothelial cells.

Enhancement of tumor invasion depends on transdifferentiation of skin fibroblasts mediated by reactive oxygen species

Myofibroblasts, pivotal for tumor progression, populate the microecosystem of reactive stroma. Using an in vitro tumor-stroma model of skin carcinogenesis, we report here that tumor-cell-derived transforming growth factor β1 (TGFβ1) initiates reactive oxygen species-dependent expression of α-smooth muscle actin, a biomarker for myofibroblastic cells belonging to a group of late-responsive genes. Moreover, protein kinase C (PKC) is involved in lipid hydroperoxide-triggered molecular events underlying transdifferentiation of fibroblasts to myofibroblasts (mesenchymal-mesenchymal transition, MMT). In contrast to fibroblasts, myofibroblasts secrete large amounts of hepatocyte growth factor (HGF), vascular endothelial growth factor (VEGF) and interleukin-6 (IL-6), resulting in a significant increase in the invasive capacity of tumor cells. The thiol N-acetyl-L-cysteine, the micronutrient selenite as well as selenoprotein P and the lipid peroxidation inhibitors α-tocopherol and butylated hydroxytoluene significantly lower both the number of TGFβ1-initiated myofibroblasts and the secretion of HGF, VEGF and IL-6, correlating with a diminished invasive capacity of tumor cells. This novel concept of stromal therapy, namely the protection of stromal cells against the dominating influence of tumor cells in tumor-stroma interaction by antioxidants and micronutrients, may form the basis for prevention of MMT in strategies for chemoprevention of tumor invasion.

Targeting the stromal fibroblasts: a novel approach to melanoma therapy

Classically, cancer is thought of as a genetic disease, where the step-wise acquisition of mutations initiates and drives progression. More recent thinking posits that, although cancers are initiated through genetic mutation, progression is often the result of dynamic interactions between the tumor cells and their surrounding environment.

Tumour-stroma interaction: cancer-associated fibroblasts as novel targets in anti-cancer therapy?

Stroma cells, together with extracellular matrix components, provide the microenvironment that is pivotal for cancer cell growth, invasion and metastatic progression. Characteristic stroma alterations accompany or even precede the malignant conversion of epithelial cells. Crucial in this process are fibroblasts, also termed myofibroblasts or cancer-associated fibroblasts (CAFs) that are located in the vicinity of the neoplastic epithelial cells. They are able to modify the phenotype of the epithelial cells by direct cell-to-cell contacts, through soluble factors or by modification of extracellular matrix components. Seminal functional studies in various cancer types, including breast, colon, prostate and lung cancer, have confirmed the concept that fibroblasts can determine the fate of the epithelial cell, since they are able to promote malignant conversion as well as to revert tumour cells to a normal phenotype. This review focuses on characteristic changes of fibroblasts in cancer and provides the experimental background elucidating functional properties of CAFs in the carcinogenic process. A possible implication in lung carcinogenesis is emphasised. Finally, a laser-capture- and microarray-based approach is presented, which comprehensively characterises carcinoma-associated fibroblasts in their in vivo environment for the identification of potential targets for anti-cancer therapy.

Invasion and MMP expression profile in desmoid tumours

Desmoid tumours are locally invasive soft tissue tumours in which β-catenin mediated TCF-dependent transcription is activated. The role of soluble factors secreted by the myofibroblastic desmoid tumour, which could stimulate tumour invasiveness, was investigated. Using collagen gel invasion assays, the presence of factors stimulating invasion in desmoid conditioned media (CM) could be established. Since matrix metalloproteinases (MMPs) have been implicated in the process of tumoral invasion, the expression levels of the MMP family members were evaluated. Quantitative reverse transcription–PCR was used to determine the expression levels of MMP1, MMP2, MMP3, MMP7, MMP11, MMP12, MMP13, MMP14 and the inhibitors TIMP1, TIMP2 and TIMP3. Besides overexpression of MMP7, a known TCF-dependent target gene, a striking upregulation of the expression levels of MMP1, MMP3, MMP11, MMP12 and MMP13 in desmoid tumours, compared to unaffected fibroblasts from the same patients, was found. Treating the CM of desmoids with a synthetic and a physiologic MMP inhibitor reduced the invasion-stimulating capacity of the desmoid CM by approximately 50%. These results suggest the involvement of soluble factors, released by the desmoid cells, in stimulating invasion and implicate the MMPs as facilitators of invasion.

Tenascin-C and SF/HGF produced by myofibroblasts in vitro provide convergent pro-invasive signals to human colon cancer cells through RhoA and Rac

Myofibroblasts are present at the invasion front in colon cancer. In an attempt to understand their putative proinvasive activity, we have developed an in vitro model. Myofibroblasts isolated from colon cancer tissue or obtained through transdifferentiation of colon fibroblasts by transforming growth factor (TGF)-beta stimulate invasion of colon cancer cells into collagen type I and Matrigel. We identified two convergent proinvasive agents secreted by myofibroblasts: namely scatter factor/hepatocyte growth factor (SF/HGF) and the TGF-beta-upregulated extracellular matrix glycoprotein tenascin-C (TNC), each of which is necessary though not sufficient for invasion. Myofibroblast-stimulated invasion into collagen type I is characterized by a change from a round, nonmigratory morphotype with high RhoA and low Rac activity to an elongated, migratory morphotype with low RhoA and high Rac activity. RhoA inactivation is determined by the epidermal growth factor (EGF)-like repeats of TNC through EGF-receptor signaling that confers a permissive and priming signal for the proinvasive activity of SF/HGF that activates Rac via c-Met. We confirmed the validity of this mechanism by using pharmacological modulators and dominant negative or constitutive active mutants that interfere with RhoA-Rho kinase and Rac signaling. Our in vitro results point to a new putative proinvasive signal for colon cancer cells provided by myofibroblasts in the tumor stroma.

Role of tissue stroma in cancer cell invasion

Maintenance of epithelial tissues needs the stroma. When the epithelium changes, the stroma inevitably follows. In cancer, changes in the stroma drive invasion and metastasis, the hallmarks of malignancy. Stromal changes at the invasion front include the appearance of myofibroblasts, cells sharing characteristics with fibroblasts and smooth muscle cells. The main precursors of myofibroblasts are fibroblasts. The transdifferentiation of fibroblasts into myofibroblasts is modulated by cancer cell-derived cytokines, such as transforming growth factor-beta (TGF-beta). TGF-beta causes cancer progression through paracrine and autocrine effects. Paracrine effects of TGF-beta implicate stimulation of angiogenesis, escape from immunosurveillance and recruitment of myofibroblasts. Autocrine effects of TGF-beta in cancer cells with a functional TGF-beta receptor complex may be caused by a convergence between TGF-beta signalling and beta-catenin or activating Ras mutations. Experimental and clinical observations indicate that myofibroblasts produce pro-invasive signals. Such signals may also be implicated in cancer pain. N-Cadherin and its soluble form act as invasion-promoters. N-Cadherin is expressed in invasive cancer cells and in host cells such as myofibroblasts, neurons, smooth muscle cells, and endothelial cells. N-Cadherin-dependent heterotypic contacts may promote matrix invasion, perineural invasion, muscular invasion, and transendothelial migration; the extracellular, the juxtamembrane and the beta-catenin binding domain of N-cadherin are implicated in positive invasion signalling pathways. A better understanding of stromal contributions to cancer progression will likely increase our awareness of the importance of the combinatorial signals that support and promote growth, dedifferentiation, invasion, and ectopic survival and eventually result in the identification of new therapeutics targeting the stroma.

Alpha smooth muscle actin positive stromal cells in gastric carcinoma

AIMS

To investigate the distribution and roles of alpha smooth muscle actin (ASMA) positive stromal cells (ASMA+ cells), which belong to the myofibroblast group, within gastric carcinomas, with reference to three histological types (diffuse type, intestinal type, and solid type).

METHODS

In total, 74 surgically resected gastric carcinomas (24 diffuse type, 43 intestinal type, and seven solid type) were examined. ASMA positive and high molecular weight caldesmon (HCD) negative stromal cells were regarded as ASMA+ cells. The distribution of CD34 positive stromal cells (CD34+ cells) was also analysed immunohistochemically.

RESULTS

In the 24 diffuse-type gastric carcinomas, six of the 13 carcinomas invading the subserosa had ASMA+ cells in the tumour stroma, whereas all six diffuse-type gastric carcinomas confined to the submucosa and all five invading the muscularis propria had no ASMA+ cells in the tumour stroma. In the 43 intestinal-type gastric carcinomas, only five of the 21 carcinomas confined to the submucosa had ASMA+ cells in the tumour stroma, whereas 21 of the 22 intestinal-type gastric carcinomas invading the muscularis propria and the subserosa had ASMA+ cell bundles in the tumour stroma. The distribution of CD34+ cells in diffuse-type and intestinal-type gastric carcinomas was similar to that seen in a previously published series. All seven solid-type gastric carcinomas examined had ASMA+ cells but not CD34+ cells in the tumour stroma. No stromal cells double positive for ASMA and CD34 were detected within the diffuse-type tumours examined.

CONCLUSIONS

These results suggest that ASMA expression in stromal cells is associated with tumour stroma formation of diffuse-type gastric carcinomas invading the subserosa, intestinal-type gastric carcinomas invading the muscularis propria and subserosa, and solid-type gastric carcinomas.

Role of myofibroblasts at the invasion front

Tumor progression occurs within a microecosystem, where cancer cells and myofibroblasts exchange proteinases and cytokines that promote growth directly through stimulation of proliferation and survival, as well as invasion through local proteolysis of the extracellular matrix and stimulation of motility. Myofibroblasts maintain the capacity of fibroblasts to induce differentiation. Fibroblasts are the main source of tumor-associated myofibroblasts. The transition to myofibroblasts also occurs in noncancerous situations. This transition is modulated by mechanical stress and cytokines, amongst which transforming growth factor-beta. The cross-talk between cancer cells and myofibroblasts illustrates the microecosystem of tumor invasion. In order to consider myofibroblasts as a possibly new target for cancer therapy, further characterization of the molecular cross-talk between myofibroblasts and cancer cells is required.

CD34-positive stromal cells and alpha-smooth muscle actin-positive stromal cells in the tumor capsule of skin sweat gland neoplasms

To elucidate the roles of CD34-positive stromal cells and alpha-smooth muscle actin-positive stromal cells at the tumor border of skin sweat gland neoplasms, we examined expression of stromal cell markers in the tumor capsule of 19 skin sweat gland neoplasms (16 mixed tumors of the skin and three nodular hidradenomas) using monoclonal antibodies to CD34, CD31, cytokeratin 14 (CK14), alpha-smooth muscle actin (ASMA) and high molecular weight caldesmon (HCD). We regarded CD34-positive, CD31-, CK14-, ASMA- and HCD-negative stromal cells to be CD34-positive stromal cells, and ASMA-positive, HCD-, CK14-, CD34- and CD31-negative stromal cells to be ASMA-positive stromal cells. CD34-positive stromal cells were detected in the tumor capsule of all 19 of the tumors examined. In nine of the 16 mixed tumors (56%) and all of the three nodular hidradenomas, ASMA-positive stromal cells were detected at the immediate inner side of the CD34-positive stromal cell layers. These results indicate that cellular components in the tumor capsules of mixed tumors of the skin and nodular hidradenomas are CD34-positive stromal cells and ASMA-positive stromal cells, and suggest that stromal cells of these two cell types are associated with tumor capsule formation of skin sweat gland neoplasms.

Differential expression of CD34 in normal colorectal tissue, peritumoral inflammatory tissue, and tumour stroma

AIMS

To investigate the role of CD34 positive stromal cells, namely dendritic interstitial cells, in the desmoplastic stroma formation of malignant epithelial neoplasms the distribution of CD34 positive stromal cells was examined in human colorectal adenocarcinomas, peritumoral inflammatory tissue, and normal tissue.

METHODS

Forty one surgically resected human colorectal adenocarcinomas and their corresponding peritumoral inflammatory and normal tissues were examined. To distinguish CD34 positive stromal cells from vascular endothelial cells, immunostaining for both CD34 and CD31 was performed. The distribution of myofibroblasts was also analysed immunohistochemically, and double staining with CD34 and alpha smooth muscle actin (ASMA) was performed.

RESULTS

Most of the stromal cells in the normal colorectal submucosa, muscularis propria, subserosa, and perirectal tissue were positive for CD34. In contrast, the peritumoral inflammatory tissue and the tumour stroma had no CD34 positive stromal cells. The distribution of myofibroblasts was almost the same as in the aforementioned series. No stromal cells double positive for CD34 and ASMA were detected in the peritumoral inflammatory tissues.

CONCLUSIONS

Most stromal fibroblasts are CD34 positive stromal cells (dendritic interstitial cells). In colorectal adenocarcinomas, a lack of CD34 expression in stromal cells is associated with desmoplastic reaction.

Differential expression of high molecular weight caldesmon in colorectal pericryptal fibroblasts and tumour stroma

AIM

To investigate an extent of smooth muscle differentiation of pericryptal fibroblasts.

METHODS

Expression of high molecular weight caldesmon (h-CD) and alpha smooth muscle actin was investigated in 123 invasive colorectal adenocarcinomas and their surrounding non-neoplastic tissues.

RESULTS

The monoclonal antibody to h-CD, which showed predominantly positive immunostaining in well differentiated smooth muscle cells, recognised pericryptal fibroblasts, smooth muscle cells, and pericytes, but was not reactive to myofibroblasts. Antibody to alpha smooth muscle actin recognised not only pericryptal fibroblasts, smooth muscle cells, and pericytes but also myofibroblasts.

CONCLUSIONS

Pericryptal fibroblasts show greater smooth muscle differentiation than myofibroblasts and there is a possibility that they are well differentiated smooth muscle cells; h-CD is an excellent marker to discriminate pericryptal fibroblasts from myofibroblasts.