Primary human fibroblasts induce diverse tumor invasiveness: involvement of HGF as an important paracrine factor

Quantitation of ligand is critical for ligand-dependent MET signalling activation and determines MET-targeted therapeutic response in gastric cancer

BACKGROUND

Despite the promising preclinical antitumor activity of MET-targeting therapies, most clinical trials have failed. We introduced a new concept of quantitation of stroma-induced hepatocyte growth factor (HGF) to assess the actual MET signalling activity in gastric cancer (GC).

METHODS

We treated serially diluted HGF and conditioned media (CM) from cancer-associated fibroblasts (CAFs) on low MET-expressing cancer cells and investigated the phenotypical and signalling changes. Stromal proportion and MET expression in GC samples were assessed, and gene set enrichment analysis (GSEA) from the public database was performed. The antitumor effect of anti-MET treatment was examined, especially when cancer cells were activated in a ligand-dependent manner.

RESULTS

Relatively high doses of HGF or high-concentrated CM fully activated MET signalling cascades and promoted cell proliferation/invasion. High stromal proportion denoted worse patient survival in MET-positive GCs than in MET-negative ones. GSEA showed that the gene sets regarding proliferation, migration, and CAF as well as MET pathway signature were enriched in simultaneously MET- and HGF-positive samples. Sufficient ligand-dependent MET signalling activation increased the sensitivity to crizotinib.

CONCLUSIONS

We conclude that patients whose tumours have a high stromal proportion and at least low MET expression may benefit more from MET-targeted therapies.

Fibroblast-secreted hepatocyte growth factor plays a functional role in esophageal squamous cell carcinoma invasion

Squamous cell cancers comprise the most common type of human epithelial cancers. One subtype, esophageal squamous cell carcinoma (ESCC), is an aggressive cancer with poor prognosis due to late diagnosis and metastasis. Factors derived from the extracellular matrix (ECM) create an environment conducive to tumor growth and invasion. Specialized cancer-associated fibroblasts (CAFs) in the ECM influence tumorigenesis. We have shown previously that the nature and activation state of fibroblasts are critical in modulating the invasive ability of ESCC in an in vivo-like organotypic 3D cell culture, a form of human tissue engineering. Dramatic differences in invasion of transformed esophageal epithelial cells depended on the type of fibroblast in the matrix. We hypothesize that CAFs create an environment primed for growth and invasion through the secretion of factors. We find that fibroblast secretion of hepatocyte growth factor (HGF) fosters the ability of transformed esophageal epithelial cells to invade into the ECM, although other unidentified factors may cooperate with HGF. Genetic modifications of both HGF in fibroblasts and its receptor Met in epithelial cells, along with pharmacologic inhibition of HGF and Met, underscore the importance of this pathway in ESCC invasion and progression. Furthermore, Met activation is increased upon combinatorial overexpression of epidermal growth factor receptor (EGFR) and p53(R175H), two common genetic mutations in ESCC. These results highlight the potential benefit of the therapeutic targeting of HGF/Met signaling in ESCC and potentially other squamous cancers where this pathway is deregulated.

Molecular biology of malignant mesothelioma: a review

Malignant mesothelioma (MM) is an uncommon tumor with high mortality and morbidity rates. It arises from mesothelial cells that line the pleural, pericardial, peritoneal, and testicular cavities. This is a disease with an indolent course because tumors arise 20 to 40 years after exposure to an inciting agent. Extensive research has shown that mesothelial cells are transformed into MM cells through various chromosomal and cellular pathway defects. These changes alter the normal cells' ability to survive, proliferate, and metastasize. This article discusses the alterations that occur in transforming normal mesothelial cells into MM. It also details some of the signal transduction pathways that seem to be important in MM with the potential for novel targeted therapeutics.

A new in vitro model for analyzing the biological behavior of well-differentiated squamous cell carcinoma

A suitable model analyzing the behavior of well-differentiated squamous cell carcinoma has not yet been established. We tried to establish such a system using a reconstructed oral mucosa, in which T3M-1 squamous cell carcinoma cells were cultured on 3T3 fibroblast-containing collagen gel. Fibroblasts promoted the stratification and keratinization of T3M-1 cells. During growth, the Ki-67 index of T3M-1 cells with fibroblasts was higher than that of T3M-1 cells alone. Fibroblasts increased the expression of involucrin, a differentiating marker of keratinocytes, in T3M-1 cells. They also promoted the invasion of T3M-1 cells into the gel. When T3M-1 cells alone were cultured in a fibroblast-conditioned (FC) medium, the fibroblast-induced phenomena mentioned above were almost replicated. In addition, epidermal growth factqr (EGF) promoted T3M-1 cells growth, but not the invasion. cDNA microarray analysis showed that FC medium increased the expression of EGF receptor and several other mRNAs of T3M-1 cells. The data suggest that T3M-1 cells, under cancer-stromal fibroblast interaction, undergo invasive growth with their well-differentiated squamous phenotype, and that this interaction may be mediated partly by soluble molecules (e.g., EGF) in an autocrine or paracrine pathway. Our system will probably provide a useful model for analyzing the biological behavior of well-differentiated squamous cell carcinoma.

NF-κB involvement in tumor–stroma interaction of squamous cell carcinoma

We investigated the interaction between tumor cells and stromal fibroblasts in tumor invasion of oral squamous cell carcinoma. Gelatin zymography showed that high levels of matrix metalloproteinase (MMP)-9 were present in the tissue of squamous cell carcinoma. When tumor cells and fibroblasts were isolated from the tissue and cultured separately, significant levels of MMP-9 were lost in the culture media of tumor cells as well as fibroblasts. When tumor cells and fibroblasts were cocultured in the presence of tumor necrosis factor alpha, high levels of MMP-9 were recovered in the culture media. The levels of MMP-9, which were secreted from tumor cells, but not fibroblasts, correlated with the number of cocultured fibroblasts. Cocultured fibroblasts, moreover, enhanced the induction of an active form of MMP-9, cell motility, and the activation of a transcription factor NF-kappaB in tumor cells. Stromal fibroblasts may induce NF-kappaB activation and promote the invasion of oral squamous cell carcinoma.

Three-dimensional coculture of endometrial cancer cells and fibroblasts in human placenta derived collagen sponges and expression matrix metalloproteinases in these cells

OBJECTIVE

Collagen gel constitutes a valuable tool for the study of cell-matrix interactions; however, it is sometimes difficult to use the gel, in which tumor and stromal cells are cocultured, for immunohistochemistry, because it is easily broken during the process of fixation and embedding in paraffin, especially after long-term culture.

METHODS

To examine the interaction between endometrial cancer cells and fibroblasts in tumor invasion, we carried out three-dimensional (3-D) coculture of various endometrial cancer cell lines and fibroblasts in human placenta derived collagen sponges and analyzed the expression and localization of matrix metalloproteinases (MMP) and plasminogen activators (PA) in these cells by immunohistochemistry.

RESULTS

After 4 weeks of culture on the collagen sponges, endometrial cancer cells composed stratiform or glandular structures on the layer of extracellular matrix, which was composed from fibloblasts and extracellular matrix. Compared to Ishikawa cells, which were rarely invasive, HEC-1A and HEC-1BE and cocultured fibroblasts showed high invasiveness and strong expression of some proteins. In cell line HEC-1BE, MMP-1, -7, and -9, MT1-MMP, tissue inhibitors of metalloproteinases 2, and uPA showed intensive staining in both cancer cells and fibroblasts by immunohistochemistry. HEC-1A cells and cocultured fibroblasts showed expression patterns similar to those of HEC-1BE.

CONCLUSION

These results suggested that expression of MMPs and uPA was accelerated in fibroblasts surrounded by cancer cells. We believe that our 3-D coculture system has merit in that the interaction between cancer cells and stromal cells can be visually analyzed by immunohistochemistry and that experiments for a long period, at least 2 weeks, are possible. Furthermore, it is expected that some animal, e.g., nude mouse, experiments can be replaced by experiments using this culture system.

Co-cultivation of pancreatic cancer cells with orthotopic tumor-derived fibroblasts: fibroblasts stimulate tumor cell invasion via HGF secretion whereas cancer cells exert a minor regulative effect on fibroblasts HGF production

The intensive stromal reaction is one of characteristics of pancreatic exocrine carcinoma. The mutual interaction between pancreatic cancer cells and orthotopic tumor-derived fibroblasts have not been clarified yet. In this study, we sought to elucidate the mechanism underlying the tumor-stromal interaction with an in vitro coculture experimental system. Considerable strong c-Met expression was detected in seven out ten lines of human pancreatic carcinoma cells, as determined by Western blotting. For hepatocyte growth factor (HGF)-production, however, none or only trace amounts of HGF could be detected in those ten cell lines. Of the two lots of tumor-derived fibroblasts obtained from two pancreatic cancer patients, the fibroblasts capable to produce HGF could initiate an apparent invasion-stimulating response in strong c-Met-expressed Suit-2 and Panc-1 cells but not in faint expressed Mia PaCa-2 and BxPC-3 cells. A specialized HGF antagonist, NK4 would effectively inhibit the fibroblast-mediated invasive growth, thus proving the key role of the paracrine-fashioned HGF/c-Met pathway in the tumor-stromal interaction. On the other hand, the regulative action of cancer cells on HGF expression of fibroblasts was also investigated using direct or indirect coculture systems. For the fibroblasts that originally did not produce HGF, cancer cells failed to show any HGF-inductive effect. For the HGF-producing fibroblasts, despite of somewhat upregulation or downregulation in fibroblast HGF expression, the feedback regulation by studied pancreatic cancer cells in both coculture modes were relatively limited. This in vitro study sketched out the interaction between cancerous and stromal compartments with an emphasis on HGF/c-Met signal pathway, thus possibly helping to unveil the more complicated mutual modulation in vivo between pancreatic cancer and host mesenchymal tissues.

Subcutaneous adipocytes promote the differentiation of squamous cell carcinoma cell line (DJM-1) in collagen gel matrix culture

Cancer cell-stromal cell interaction plays a crucial role in the malignant growth of cancer cells. In the skin, the main stromal cell types consist of dermal fibroblasts and subcutaneous adipocytes. Fibroblasts are shown to promote the invasive growth of various cancer cell types. The interaction between cancer cells and stromal adipocytes, however, has not been sufficiently studied even in cutaneous carcinoma. To address the effects of adipocytes on the biologic behavior of cancer cells, we examined the growth and differentiation of a squamous cell carcinoma cell line of the skin (DJM-1), using a three-dimensional collagen gel matrix culture with a cutaneous environmental factor, air exposure. The growth was estimated by the uptake of bromodeoxy-uridine (BrdU) for 24 h. The BrdU indices of DJM-1 cells in stromal-cell-free, fibroblast-containing, and adipocyte- containing conditions were 19.7 +/- 1.9%, 19.8 +/- 2.8%, and 4.7 +/- 1.4%, respectively, whereas the BrdU index on the gel containing both fibroblasts and adipocytes was 10.4 +/- 3.3%. In terms of differentiation, DJM-1 cells cocultured with adipocytes constructed the best-organized stratified layer with a cornified-like structure in all conditions above. The differentiation markers involucrin and cytokeratin 10 were immunohistochemically detected in this structure of DJM-1 cells. Adipocyte-induced phenomena were not affected distinctively by air exposure. These results indicate that adipocytes, but not fibroblasts, promote the differentiation of squamous cell carcinoma cells (DJM-1) and inhibit their growth. These adipocyte-induced phenomena were not completely inhibited by fibroblasts. In conclusion, we suggest that stromal adipocytes may be involved in the differentiating mechanisms of cutaneous carcinoma cells.

Correlation between loss of E-cadherin expression and overexpression of autocrine motility factor receptor in association with progression of human gastric cancers

Loss of intercellular adhesion and increased cell motility synergistically facilitate tumor cell invasion. We studied these factors in 90 patients with gastric cancers by using an immunohistochemical technique to detect strong or weak expression of E-cadherin (ECD) and autocrine motility factor receptor (AMFR). Normal gastric mucosa (control) reacted strongly for ECD and weakly for AMFR. In study cases, ECD was weak in 47 cases, and AMFR was strong in 39 cases. Weak ECD and strong AMFR expression were associated with tumor dedifferentiation. AMFR expression correlated positively with depth of invasion but not with lymph node metastasis. ECD expression correlated negatively with lymph node metastasis but not with depth of invasion. A strong inverse correlation was found between ECD and AMFR expression. Tumors with weak ECD and strong AMFR expression displayed a more aggressive phenotype than tumors with strong ECD and weak AMFR expression. The postoperative survival of patients with tumors with weak ECD and strong AMFR expression was significantly shorter than that of other groups. Since they are involved in the pathway to development of tumors with a more aggressive phenotype, ECD and AMFR should be examined to evaluate the biologic potential of gastric cancers.

Role of fibroblasts in HGF/SF-induced cohort migration of human colorectal carcinoma cells: fibroblasts stimulate migration associated with increased fibronectin production via upregulated TGF-beta1

Carcinoma cells frequently invade the surrounding tissue as coherent clusters or nests of cells. We have called this type of movement "cohort migration." We have previously presented an in vitro two-dimensional cohort migration model, in which highly metastatic variant L-10 cells of human rectal adenocarcinoma cell line RCM-1 moved as coherent cell sheets when stimulated with 12-O-tetradecanoylphorbol-13-acetate (TPA) or hepatocyte growth factor/scatter factor (HGF/SF). Pericellular deposition of EDA-containing fibronectin (EDA+FN) was essential for TPA-induced cohort migration. In this study, we investigated how colon-derived fibroblasts could affect the induction of cohort migration of colorectal carcinoma cells by HGF/SF, since carcinoma cell-fibroblast interactions frequently regulate biological events during cancer cell invasion. Fibroblasts co-cultured with L-10 carcinoma cells stimulated HGF/SF-induced cohort migration of L-10 cells up to 2 to 3-fold. Conditioned medium (CM) from fibroblasts that were cultured alone was not effective but CM from fibroblasts cocultured with carcinoma cells enhanced HGF/SF-induced cohort migration, and this effect in CM was found to be mediated by TGF-beta1 upregulated in co-cultured conditions. Among the motogenic growth factors examined, only TGF-beta1 synergistically stimulated HGF/SF-induced L-10 cell cohort migration, although TGF-beta1 alone did not induce cohort migration. TGF-beta1 also exhibited synergistic effect in several other human colorectal carcinoma cell lines. The synergistic stimulation of L-10 cell cohort migration by HGF/SF and TGF-beta1 was associated with increased production of motility-enhancing EDA+FN by L-10 cells, and blocking FN with a specific antibody effectively inhibited the synergistic effect.

Amplification and overexpression of the hepatocyte growth factor receptor (HGFR/MET) in rat DMBA sarcomas

In the present study subcutaneous fibrosarcomas were induced by the carcinogen 7,12-dimethylbenz(a)anthracene (DMBA) in rats from F1 generation cross breedings of two different inbred strains. Comparative genomic hybridization (CGH) analysis, which allows detection of DNA sequence copy changes, was applied to one of the tumors and it was found that there were increased copy numbers of sequences at chromosome 4q12-q21 in this tumor. We have previously determined that the loci for the hepatocyte growth factor (Hgf) and hepatocyte growth factor receptor (Hgfr/Met), a protooncogene, are situated in this particular chromosome region. Using probes for the two genes in FISH (fluorescence in situ hybridization) and in Southern blots we found that the Hgfr/Met gene was amplified in five of the 19 sarcomas studied, and that the Hgf gene was coamplified in two of them. Northern and Western blots and tyrosine phosphorylation analysis showed that the HGF receptor was overexpressed and functional in all five tumors, as well as in two additional tumors. In summary, both amplification and overexpression of the Hgfr/Met gene was found in about 25% of DMBA-induced experimental rat sarcomas, and HGF receptor overexpression alone was seen in two additional tumors. Possibly this reflects an involvement in paracrine or autocrine stimulation of growth and invasiveness by HGF. Our finding could provide a rodent model system to increased knowledge about causality and therapy, which may be applicable to the sizeable fraction of human musculoskeletal tumors displaying MET overexpression.

Expression of E-cadherin in oral cancer cell lines and its relationship to invasiveness in SCID mice in vivo

We examined the expression of E-cadherin in nine oral cancer cell lines. HSC-4, NA, ZA, HOC927 and Ca9-22 cells strongly expressed E-cadherin [E-CD(++) cell line] and HSC-2 and HSC-3 cells weakly expressed E-cadherin [E-CD(+) cell line]. All the cell lines that expressed E-cadherin were of cuboidal morphology and formed cobblestone colonies. In contrast, TSU and HOC313 cells had spindle shapes, formed dispersed colonies, and were completely negative for E-cadherin [E-CD(-) cell line]. Moreover, all cell lines that expressed E-cadherin showed tumorgenicity in SCID mice, but E-CD(-) cell lines did not show tumorgenicity. The tumors derived from E-CD(+) cell lines invaded deeper into the connective tissues than those from E-CD(++) cell lines. In immunohistochemical analysis, the difference was more marked at the edges of the cancer nests. These results suggest that E-cadherin expression was relevant to the cell forms and the differential grade of cultured cells and that reduced E-cadherin in oral cancer may be associated with invasiveness in vivo.

Nonsteroidal anti-inflammatory drugs may prevent colon cancer through suppression of hepatocyte growth factor expression

Nonsteroidal anti-inflammatory drugs which inhibit cyclooxygenase have been reported to suppress colon carcinogenesis. However the mechanism has not yet been elucidated. Growth factors such as hepatocyte growth factor, which are produced by fibroblasts, have been shown to be important in carcinogenesis and the progression of various human cancers. In the present study, we tested the hypothesis that nonsteroidal anti-inflammatory drugs inhibit hepatocyte growth factor expression through an endogenous prostaglandin-mediated pathway in cultured human colonic fibroblasts. Human colonic fibroblasts were obtained from a resected colon and cultured. Hepatocyte growth factor and prostaglandin E2 were measured by enzyme-linked immunosorbent assay. Induction of cyclooxygenase-1 and cyclooxygenase-2 protein was estimated by immunoblotting. Prostaglandins increased hepatocyte growth factor production significantly in a dose- and time-dependent manner. Cholera toxin and 8-bromo cAMP also stimulated hepatocyte growth factor production. Further, prostaglandin E1 significantly increased cellular cAMP. The prostaglandin EP2 and EP4 receptors were detected by reverse transcription-polymerase chain reaction. Interleukin-1beta dramatically increased prostaglandin E2 production and significantly stimulated hepatocyte growth factor synthesis. Interleukin-1beta induced cyclooxygenase-2 but not cyclooxygenase-1 protein. Indomethacin significantly reduced interleukin-1beta-induced prostaglandin E2 release and hepatocyte growth factor production. These results suggest that prostaglandin is a factor for the production of hepatocyte growth factor by human colonic fibroblasts. Nonsteroidal anti-inflammatory drugs may suppress colon carcinogenesis, in part, through the suppression of hepatocyte growth factor expression by inhibiting endogenous prostaglandin production.

Evaluation of hepatocyte growth factor activator inhibitor expression in normal and malignant colonic mucosa

Gene expression of hepatocyte growth factor activator inhibitor (HAI), a recently identified Kunitz-type serine proteinase inhibitor, was analyzed in a series of human colorectal carcinoma cell lines and in human colorectal tissues. All of the 14 cell lines derived from adenocarcinoma of the colorectum expressed HAI in vitro, whereas a colon carcinoma cell line of neuroendocrine origin did not. In vivo, HAI was consistently expressed in the normal colorectal mucosa. Although the expression of HAI mRNA was conserved in adenocarcinoma tissues of the colorectum, the levels of expression were decreased in the adenocarcinoma tissues compared to the normal counterparts. There was a tendency towards an inverse correlation, albeit not well defined, between the amounts of HAI mRNA and the tumor progression. Immunohistochemical study indicated that HAI protein is present predominantly on the surface of epithelial cells of the colon and the immunoreactivity was decreased in the adenocarcinoma cells.

Serum concentration of hepatocyte growth factor in patients with metastatic breast cancer

The serum concentration of hepatocyte growth factor (HGF) was examined in 34 patients with metastatic breast cancer. Although no significant difference was observed between HGF concentration and the site of metastasis, serum HGF levels were slightly higher in patients with liver metastasis and in patients with multiple metastatic sites than in patients with other lesions. Significantly higher levels of serum HGF were observed in patients with progressive metastasis of breast cancer compared with those with stable metastasis. The patients with high HGF levels exhibited a significantly shorter survival rate than those with low HGF levels. Circulating HGF levels may be a useful indicator for the progression of metastatic lesions and the prognosis of patients with metastatic breast cancer.

Frequency of chromosome 7 gain in human breast cancer cells: correlation with the number of metastatic lymph nodes and prognosis

Trisomy 7 has been reported in various malignant neoplasms, but there are no reports in breast cancer. In order to evaluate the contribution of chromosome 7 gain to breast cancer, we investigated the relationship of numerical abberation of chromosome 7 with clinicopathological variables and prognosis in seventy-nine breast cancer cases (invasive carcinomas) using the technique of fluorescence in situ hybridization (FISH) on paraffin-embedded sections. A significant correlation of the frequency of cells with extra copies of chromosome 7 (percent polysomy 7 cell score) was found with tumor size, regional lymph node status, tnm stage, histological extension, estrogen receptor (ER), and DNA ploidy. The number of metastatic lymph nodes was positively correlated with percent polysomy 7 cell score (correlation coefficient=0.623, p < 0.01). Furthermore, cases with a high percent polysomy 7 cell score had a shorter disease-free survival and overall survival times, especially in the lymph node-positive group. It was demonstrated that percent polysomy 7 cell value was closely associated with lymph node metastasis and prognosis and might be a useful prognostic predictor of breast cancer patients.