2335

FN1

fibronectin 1;FN1;fibronectin 1

cold-insoluble globulin|fibronectin|migration-stimulating factor

2q34

protein-coding

Although the outgrowth of micrometastases into macrometastases is the rate-limiting step in metastatic progression and the main determinant of cancer fatality, the molecular mechanisms involved have been little studied. Here, we compared the gene expression profiles of melanoma lymph node micro- and macrometastases and unexpectedly found no common up-regulation of any single growth factor/cytokine, except for the cytokine-like SPP1. Importantly, metastatic outgrowth was found to be consistently associated with activation of the transforming growth factor-beta signaling pathway (confirmed by phospho-SMAD2 staining) and concerted up-regulation of POSTN, FN1, COL-I, and VCAN genes-all inducible by transforming growth factor-beta. The encoded extracellular matrix proteins were found to together form intricate fibrillar networks around tumor cell nests in melanoma and breast cancer metastases from various organs. Functional analyses suggested that these newly synthesized protein networks regulate adhesion, migration, and growth of tumor cells, fibroblasts, and endothelial cells. POSTN acted as an anti-adhesive molecule counteracting the adhesive functions of FN1 and COL-I. Further, cellular FN and POSTN were specifically overexpressed in the newly forming/formed tumor blood vessels. Transforming growth factor-beta receptors and the metastasis-related matrix proteins, POSTN and FN1, in particular, may thus provide attractive targets for development of new therapies against disseminated melanoma, breast cancer, and possibly other tumors, by affecting key processes of metastasis: tumor/stromal cell migration, growth, and angiogenesis.

We previously established that overexpression of the EGF receptor (EGFR) is sufficient to induce tumor formation by otherwise nontransformed mammary epithelial cells, and that the initiation of epithelial-mesenchymal transition (EMT) is capable of increasing the invasion and metastasis of these cells. Using this breast cancer (BC) model, we find that in addition to EGF, adhesion to fibronectin (FN) activates signal transducer and activator of transcription 3 (STAT3) through EGFR-dependent and -independent mechanisms. Importantly, EMT facilitated a signaling switch from SRC-dependent EGFR:STAT3 signaling in pre-EMT cells to EGFR-independent FN:JAK2:STAT3 signaling in their post-EMT counterparts, thereby sensitizing these cells to JAK2 inhibition. Accordingly, human metastatic BC cells that failed to activate STAT3 downstream of EGFR did display robust STAT3 activity upon adhesion to FN. Furthermore, FN enhanced outgrowth in three-dimensional organotypic cultures via a mechanism that is dependent upon beta1 integrin, Janus kinase 2 (JAK2), and STAT3 but not EGFR. Collectively, our data demonstrate that matrix-initiated signaling is sufficient to drive STAT3 activation, a reaction that is facilitated by EMT during BC metastatic progression.

Recent evidence has been suggesting the important roles of endothelial cells (ECs) involved in the pathogenesis of several cancers, including colorectal carcinomas (CRCs), but the underlying mechanism remains elusive. We have demonstrated previously that CRC-derived fibronectin extra domain A (EDA) promotes vasculogenesis, tumorigenesis and metastasis of CRCs. At the current study, we showed that EC-secreted EDA promotes the metastatic capacity CRC cells via inducing an epithelial-mesenchymal transition. In vitro and in vivo experiments showed that EC-secreted EDA, via the interaction with integrin alpha9beta1 on neighboring CRC cells, leads to the activation of focal adhesion kinase as well as Rac signalings, thus strengthens the polarity of cytoskeleton and promotes the invasion capacity of CRC cells. Furthermore, Erk signaling pathway was revealed to critically mediate the effect of EC-derived EDA on CRC cells. Our findings reveal a novel oncogenic role of ECs in promoting CRC malignancy through secreting EDA.

OBJECTIVE: To investigate the expression of collagen type I (Col I), collagen type IV (Col IV) and fibronectin (Fn) in laryngeal squamous cell carcinomas (LSCC) and their pathobiological relationship with invasion and metastasis of tumor. METHOD: The expression of Col I, Col IV and Fn was detected by immunohistochemistry method in normal tissue of latero-carcinoma and tissue of carcinoma in 60 specimens of LSCC. Integral optical density (iOD) was detected by image analysis of computer and was analyzed by SPSS13.0. RESULT: The expression of Col I was obvious and integrity. The expression of Col IV and Fn of basal membrane was like intact line-shape appearance and Fn of interstitial substance appeared like a complete network in the normal tissue of latero-carcinoma. Their expression decreased gradually and their integrity was broken and disappeared gradually from well to poorly differentiated LSCC. Their expressions also fell off with the tumor size, clinical stage and cervical lymphatic metastasis gradually and consistently in LSCC. Their variances were statistical significance separately (P<0.05 or P<0.01). CONCLUSION: The expression of Col I, Col IV and Fn was closely related to tumor invasion, the regional lymph node metastasis and other some pathobiological features in LSCC. A detection of Col I, Col IV and Fn was of definite significance on a better comprehension of the possibility of metastasis, choice of surgery and prognosis.

Although the outgrowth of micrometastases into macrometastases is the rate-limiting step in metastatic progression and the main determinant of cancer fatality, the molecular mechanisms involved have been little studied. Here, we compared the gene expression profiles of melanoma lymph node micro- and macrometastases and unexpectedly found no common up-regulation of any single growth factor/cytokine, except for the cytokine-like SPP1. Importantly, metastatic outgrowth was found to be consistently associated with activation of the transforming growth factor-beta signaling pathway (confirmed by phospho-SMAD2 staining) and concerted up-regulation of POSTN, FN1, COL-I, and VCAN genes-all inducible by transforming growth factor-beta. The encoded extracellular matrix proteins were found to together form intricate fibrillar networks around tumor cell nests in melanoma and breast cancer metastases from various organs. Functional analyses suggested that these newly synthesized protein networks regulate adhesion, migration, and growth of tumor cells, fibroblasts, and endothelial cells. POSTN acted as an anti-adhesive molecule counteracting the adhesive functions of FN1 and COL-I. Further, cellular FN and POSTN were specifically overexpressed in the newly forming/formed tumor blood vessels. Transforming growth factor-beta receptors and the metastasis-related matrix proteins, POSTN and FN1, in particular, may thus provide attractive targets for development of new therapies against disseminated melanoma, breast cancer, and possibly other tumors, by affecting key processes of metastasis: tumor/stromal cell migration, growth, and angiogenesis.

Although the outgrowth of micrometastases into macrometastases is the rate-limiting step in metastatic progression and the main determinant of cancer fatality, the molecular mechanisms involved have been little studied. Here, we compared the gene expression profiles of melanoma lymph node micro- and macrometastases and unexpectedly found no common up-regulation of any single growth factor/cytokine, except for the cytokine-like SPP1. Importantly, metastatic outgrowth was found to be consistently associated with activation of the transforming growth factor-beta signaling pathway (confirmed by phospho-SMAD2 staining) and concerted up-regulation of POSTN, FN1, COL-I, and VCAN genes-all inducible by transforming growth factor-beta. The encoded extracellular matrix proteins were found to together form intricate fibrillar networks around tumor cell nests in melanoma and breast cancer metastases from various organs. Functional analyses suggested that these newly synthesized protein networks regulate adhesion, migration, and growth of tumor cells, fibroblasts, and endothelial cells. POSTN acted as an anti-adhesive molecule counteracting the adhesive functions of FN1 and COL-I. Further, cellular FN and POSTN were specifically overexpressed in the newly forming/formed tumor blood vessels. Transforming growth factor-beta receptors and the metastasis-related matrix proteins, POSTN and FN1, in particular, may thus provide attractive targets for development of new therapies against disseminated melanoma, breast cancer, and possibly other tumors, by affecting key processes of metastasis: tumor/stromal cell migration, growth, and angiogenesis.

tumor-associated macrophages (TAMs) are key orchestrators of the tumor microenvironment directly affecting neoplastic cell growth, neoangiogenesis, and extracellular matrix remodeling. In turn, the tumor milieu strongly influences maturation of TAMs and shapes several of their features. To address the early macrophage (M) differentiation phase in a malignant context, we mimicked a tumor microenvironment by in vitro coculturing human blood monocytes with conditioned media from different cancer cell lines. Only 2 out of 16 tumor cell lines induced M differentiation due to secreted M-CSF isoforms, including high molecular mass species. A global gene profiling of tumor-conditioned M was performed. Comparison with other datasets (polarized M1-M, M2-M, and TAMs isolated from human tumors) highlighted the upregulation of several genes also shared by TAM and M2-polarized M. The most expressed genes were selenoprotein 1, osteoactivin, osteopontin, and, interestingly, migration-stimulating factor (MSF), a poorly studied oncofoetal isoform of fibronectin. MSF (present in fetal/cancer epithelial and stromal cells but not in healthy tissues) was never identified in M. MSF production was confirmed by immunohistochemistry in human TAMs. MSF was induced by M-CSF, IL-4, and TGFbeta but not by proinflammatory stimuli. RNA and protein analysis clearly demonstrated that it is specifically associated with the M2 polarization of M. tumor-conditioned M-derived MSFs strongly stimulated tumor cell migration, thus contributing to the motile phenotype of neoplastic cells. In conclusion, MSF is a new molecule associated with the M2 polarization of M and expressed by TAMs. Its biological function may contribute to M-mediated promotion of cancer cell invasion and metastasis.

In human tumors, fibronectin (FN) expression is positively associated with tumor metastatic potential and matrix metalloproteinase (MMP) secretion. Additionally, tissue transglutaminase (TG2) is implicated as playing an important role in tumor progression, and acts as a co-receptor for integrin-mediated cell binding to FN. This study explored the involvement of FN and TG2 in cancer cell metastasis using the recently established highly invasive A431-III subline. A431-III cells expressed significantly higher levels of FN and TG2 as compared to the parental line (A431-P). Knockdown of endogenous FN by small interfering RNA (siRNA) resulted in dramatic suppression of the migratory and invasive activity, and the secreted MMP-9 activity (but not MMP-2) in A431-III subline. Exogenous administration of FN to A431-III cells also increased the secreted activity of MMP-9 but not MMP-2. Interestingly, knockdown of TG2 by siRNA dramatically reduced the cell attachment, migration and invasion, and the secretion of MMP-9 and MMP-1 (but not MMP-2 and MMP-3) in A431-III cells as compared to A431-P cells. Furthermore, A431-III cells exhibited increased association of integrin beta1 and beta3 with FN and TG2, and knockdown of TG2 markedly suppressed integrin beta1 interaction with FN. Together, this study suggests that FN and TG2 facilitate the metastatic activity of A431 tumor cells, and this may be partly attributed to TG2 enhancement of the association of FN and beta integrin. In addition, the combined targeting of TG2 and FN may be an effective therapeutic strategy for cancer displaying increased expression of both proteins.

Ovarian cancer (OvCa) metastasizes to organs in the abdominal cavity, such as the omentum, which are covered by a single layer of mesothelial cells. Mesothelial cells are generally thought to be "bystanders" to the metastatic process and simply displaced by OvCa cells to access the submesothelial extracellular matrix. Here, using organotypic 3D cultures, we found that primary human mesothelial cells secrete fibronectin in the presence of OvCa cells. Moreover, we evaluated the tumor stroma of 108 human omental metastases and determined that fibronectin was consistently overexpressed in these patients. Blocking fibronectin production in primary mesothelial cells in vitro or in murine models, either genetically (fibronectin 1 floxed mouse model) or via siRNA, decreased adhesion, invasion, proliferation, and metastasis of OvCa cells. Using a coculture model, we determined that OvCa cells secrete TGF-beta1, which in turn activates a TGF-beta receptor/RAC1/SMAD-dependent signaling pathway in the mesothelial cells that promotes a mesenchymal phenotype and transcriptional upregulation of fibronectin. Additionally, blocking alpha5 or beta1 integrin function with antibodies reduced metastasis in an orthotopic preclinical model of OvCa metastasis. These findings indicate that cancer-associated mesothelial cells promote colonization during the initial steps of OvCa metastasis and suggest that mesothelial cells actively contribute to metastasis.

BACKGROUND: Papillary thyroid carcinoma (PTC) is often accompanied by lymph node metastasis (LNM), compared with follicular thyroid carcinoma (FTC). Sialic acid is carried by fibronectin (sFN) as the antigen of monoclonal antibody (MoAb) JT-95 detected in 90% of PTC, and a few cases of FTC. PATIENTS AND METHODS: JT-95 staining was performed in 9 PTC and 20 follicular type tumors to investigate the relationship between the expression of sFN and the frequency of LNM. RESULTS: There were 11 cases with LNM from 23 malignant tumors, and no cases of LNM from 6 benign follicular type tumors. The staining scores by JT-95 of the 11 tumors with LNM were 5+ in 4 cases, and 6+ in 7 cases. On the other hand, the scores of 12 malignant tumors without LNM were <4+ in all cases. CONCLUSION: An increase of sFN expression in thyroid malignancies is correlated with LNM.

AIM: This study assessed if onfFN mRNA in the peripheral blood of patients with DTC can identify individuals with metastatic disease. METHODS: Comparison of onfFN mRNA was made among 3 groups: disease-free, lymph node metastasis, and distant metastasis using real-time RT-PCR on 5 ml blood samples from each DTC patient. RESULTS: Fifty-one patients were included: 30 (59%) were disease-free; 7 (13.7%) had lymph node metastasis; and 14 (27.5%) had distant metastasis. OnfFN mRNA levels in the 3 groups were significantly different (P=0.001) but with a large overlap and the expression being highest in the disease-free group. Subgroup analysis of the metastatic groups did not show any effect of age, cell type, and serum TSH, Tg, and antiTg on onfFN mRNA. The within-run and between-run root mean square coefficients of variations were <2%. CONCLUSION: OnfFN mRNA in patients with DTC cannot identify those with metastatic disease.