Decreased fibronectin expression in Met/HGF-mediated tumorigenesis

Shaping Oncogenic Microenvironments: Contribution of Fibronectin

The extracellular matrix (ECM) is a complex network of proteins and glycans, dynamically remodeled and specifically tailored to the structure/function of each organ. The malignant transformation of cancer cells is determined by both cell intrinsic properties, such as mutations, and extrinsic variables, such as the mixture of surrounding cells in the tumor microenvironment and the biophysics of the ECM. During cancer progression, the ECM undergoes extensive remodeling, characterized by disruption of the basal lamina, vascular endothelial cell invasion, and development of fibrosis in and around the tumor cells resulting in increased tissue stiffness. This enhanced rigidity leads to aberrant mechanotransduction and further malignant transformation potentiating the de-differentiation, proliferation and invasion of tumor cells. Interestingly, this fibrotic microenvironment is primarily secreted and assembled by non-cancerous cells. Among them, the cancer-associated fibroblasts (CAFs) play a central role. CAFs massively produce fibronectin together with type I collagen. This review delves into the primary interactions and signaling pathways through which fibronectin can support tumorigenesis and metastasis, aiming to provide critical molecular insights for better therapy response prediction.

Integrated Transcriptomics-Proteomics Analysis Identifies Molecular Phenotypic Alterations Associated with Colorectal Cancer

Understanding the pathogenesis and finding diagnostic markers for colorectal cancer (CRC) are the key to its diagnosis and treatment. Integrated transcriptomics and proteomics analysis can be used to characterize alterations of molecular phenotypes and reveal the hidden pathogenesis of CRC. This study employed a novel strategy integrating transcriptomics and proteomics to identify pathological molecular pathways and diagnostic biomarkers of CRC. First, differentially expressed proteins and coexpressed genes generated from weighted gene coexpression network analysis (WGCNA) were intersected to obtain key genes of the CRC phenotype. In total, 63 key genes were identified, and pathway enrichment analysis showed that the process of coagulation and peptidase regulator activity could both play important roles in the development of CRC. Second, protein-protein interaction analysis was then conducted on these key genes to find the central genes involved in the metabolic pathways underpinning CRC. Finally, Itih3 and Lrg1 were further screened out as diagnostic biomarkers of CRC by applying statistical analysis on central genes combining transcriptomics and proteomics data. The deep involvement of central genes in tumorigenesis demonstrates the accuracy and reliability of this novel transcriptomics-proteomics integration strategy in biomarker discovery. The identified candidate biomarkers and enriched metabolic pathways provide insights for CRC diagnosis and treatment.

The role of ADAM8 in the mechanophenotype of MDA-MB-231 breast cancer cells in 3D extracellular matrices

The majority of investigations of cancer cells have been performed in an oversimplified 2D in vitro environment. In the last decade there is a trend toward more sophisticated 3D in vitro cell culture model systems that can bridge the existing gap between 2D in vitro and in vivo experiments in the field of biophysical and cell biological cancer cell research. Here, we hypothesize that the bidirectional interplay between breast cancer cells and their tumor microenvironment is critical for the outcome of the disease. Thereby, the tissue remodeling processes evoked by cancer cells are important for cancer cell-driven mechanical probing of their matrix environment and on cancer cell adhesion and motility. When remodeling processes have been explored, the emphasis was placed on matrix metalloproteinases and rather not on a disintegrin and metalloproteases (ADAMs). However, the role of ADAM8 in cell mechanics regulating cellular motility in 3D collagen matrices is still unclear. Thus, in this study, we focus on the function of ADAM8 in matrix remodeling and migration of 3D extracellular matrix scaffolds. Therefore, human MDA-MB-231 breast carcinoma cells with ADAM8 knocked down, referred to as ADAM8-KD cells, as well as MDA-MB-231 scrambled control cells, referred to as ADAM8-Ctrl cells, have been used to examine their ability to interact with and migrate in dense extracellular 3D matrices. The fiber displacements, as the capacity of cells to deform the environmental 3D matrix scaffold, has been observed. ADAM8-KD cells displace collagen fibers more strongly than ADAM8-Ctrl cells. Moreover, ADAM8-KD cells migrated more numerous in 3D collagen matrices compared to ADAM8-Ctrl cells. The impairment of ADAM8 using the ADAM8 inhibitor BK-1361 led to significantly increased fiber displacements of ADAM8-Ctrl cells to the levels of ADAM8-KD cells. In contrast, the inhibitor had no effect on ADAM8-KD cells in terms of fiber displacements as well as on the quantitative characteristics of cell invasion of ADAM8-Ctrl cells, albeit the cells that were found in the matrix invaded considerably deeper. When matrix remodeling by cells is impaired through GM6001, a broad-band metalloproteinase inhibitor, the fiber displacements of both cell types increased. In fact, ADAM8 is known to degrade fibronectin in a direct and/or indirect manner. The supplementation of fibronectin before polymerization of the 3D collagen matrices caused an enhancement in fiber displacements as well as in cell invasion into fibronectin-collagen matrices of ADAM8-Ctrl cells, whereas the fiber displacements of ADAM8-KD cells did not change. However, fibrinogen and laminin supplementation induced an increase in fiber displacements of both cell types. Thus, the impact of fibronectin on selective increase in fiber displacement of ADAM8-Ctrl cells appears to be ADAM8-dependent. As a consequence, the presence of ADAM8 may provide an explanation for the longstanding controversial results of fibronectin enrichment on malignant progression of cancers such as breast cancer. Finally, ADAM8 is apparently essential for providing cell-driven fiber displacements of the extracellular matrix microenvironment, which fosters 3D motility in a fibronectin-rich environment. Contribution to the field. Currently, the role of ADAM8 has been explored in 2D or at maximum 2.5D in vitro cell culture motility assays. However, the mechanical characteristics of these two cell types have not been examined. In this study, the function of ADAM8 in breast cancer is refined by providing in vitro cell investigations in 3D collagen fiber matrices of various conditions. ADAM8 has been shown to be involved in the reduced generation of fiber displacements and in influencing breast cancer cell migration. However, especially in the presence of fibronectin in 3Dcollagen fiber matrices, the fiber displacements of ADAM8-Ctrl cells are increased.

Glycoproteomic Analysis Reveals Aberrant Expression of Complement C9 and Fibronectin in the Plasma of Patients with Colorectal Cancer

Colorectal cancer (CRC) is a major cause of cancer mortality. Currently used CRC biomarkers provide insufficient sensitivity and specificity; therefore, novel biomarkers are needed to improve the CRC detection. Label-free quantitative proteomics were used to identify and compare glycoproteins, enriched by wheat germ agglutinin, from plasma of CRC patients and age-matched healthy controls. Among 189 identified glycoproteins, the levels of 7 and 15 glycoproteins were significantly altered in the non-metastatic and metastatic CRC groups, respectively. Protein-protein interaction analysis revealed that they were predominantly involved in immune responses, complement pathways, wound healing and coagulation. Of these, the levels of complement C9 (C9) was increased and fibronectin (FN1) was decreased in both CRC states in comparison to those of the healthy controls. Moreover, their levels detected by immunoblotting were validated in another independent cohort and the results were consistent with in the study cohort. Combination of CEA, a commercial CRC biomarker, with C9 and FN1 showed better diagnostic performance. Interestingly, predominant glycoforms associated with acetylneuraminic acid were obviously detected in alpha-2 macroglobulin, haptoglobin, alpha-1-acid glycoprotein 1, and complement C4-A of CRC patient groups. This glycoproteomic approach provides invaluable information of plasma proteome profiles of CRC patients and identification of CRC biomarker candidates.

Fibronectin in Cancer: Friend or Foe

The role of fibronectin (FN) in tumorigenesis and malignant progression has been highly controversial. Cancerous FN plays a tumor-suppressive role, whereas it is pro-metastatic and associated with poor prognosis. Interestingly, FN matrix deposited in the tumor microenvironments (TMEs) promotes tumor progression but is paradoxically related to a better prognosis. Here, we justify how FN impacts tumor transformation and subsequently metastatic progression. Next, we try to reconcile and rationalize the seemingly conflicting roles of FN in cancer and TMEs. Finally, we propose future perspectives for potential FN-based therapeutic strategies.

Hepatocyte growth factor suppresses transforming growth factor-beta-1 and type III collagen in human primary renal fibroblasts

Tubulointerstitial changes in the diabetic kidney correlate closely with renal fibrosis, and transforming growth factor-beta-1 (TGF-beta1) is thought to play a key role in this process. In contrast, hepatocyte growth factor (HGF) has shown therapeutic effects on injured renal tubules in animal models. This study was undertaken to test the hypothesis that the preventive effects of HGF may result from interventions in TGF-beta1-mediated signaling and collagen III secretion. We examined the expression of HGF/HGF receptor (c-Met) and TGF-beta1 in renal fibroblasts at multiple time points. The effects of recombinant human HGF on TGF-beta1 expression were studied by RT-PCR and Western blotting, and the levels of collagen III were measured by ELISA. In the high-glucose condition, the expression of HGF and c-Met in renal fibroblasts was detected as early as 6 hours following cell culture while the level of TGF-beta1 peaked at 96 hours. The addition of recombinant human HGF to the culture media dose-dependently inhibited TGF-beta1 mRNA expression and reduced collagen III secretion by 34%. These results indicate that, during hyperglycemia, HGF inhibits TGF-beta1 signaling and type III collagen activation in interstitial fibroblasts. Furthermore, we should recognize that changes in the balance between HGF and TGF-beta1 might be decisive in the pathogenesis of chronic renal fibrosis. Therefore, administration of HGF to restore this balance may offer a novel therapeutic intervention in managing renal fibrogenesis in diabetic nephropathy.

The effect of tezosentan after cold ischemia and renal artery clamping as a model of reperfusion injury in newborn piglets

BACKGROUND

Cold ischemia and clamping of the renal artery contribute to acute tubular necrosis and renal dysfunction of transplant grafts. The mechanism of ischemic injury is not fully understood, but endothelin (ET)-1 and -2 have been found to participate in reperfusion injury. ET receptor blockade has been shown to have renoprotective effects in both warm and cold reperfusion injury.

OBJECTIVE

We sought to assess the effect of tezosentan, a competitive ET antagonist, on piglet renal function during cold ischemia and renal artery clamping.

DESIGN/METHODS

Sixteen piglets (7 to 10 days old) were prepped and assigned to three experimental groups: piglets with kidneys clamped (KCLAMP), with kidneys wrapped in ice (KICE), and piglets treated with tezosentan injected after 45 minutes of clamping and ice (KTEZO). Preexperiment parameters including vital signs, urine volume, glomerular filtration rate (GFR), paraaminohippuric acid clearance (CPAH), fractional excretion of sodium and potassium (FeNa, FeK), and renal blood flow (RBF) were measured at baseline, then at 1- and 2-hour intervals.

RESULTS

The decrease in urine volume was comparable in both KCLAMP and KICE groups, but no UV decrease was observed in KTEZO group. RBF and GFR were similar (26% to 52% decrease) in all three groups. FeNa decreased by >50% in KICE, whereas it increased by 60% in KTEZO when compared with baseline. A similar increase in FeK was observed in all three groups.

CONCLUSIONS

Cold ischemia and clamping have deleterious effects on RBF, GFR, and FeNa. ET blockade did not have a renoprotective effect except on urine volume when given soon after the injury.

Invasion of normal human fibroblasts induced by v-Fos is independent of proliferation, immortalization, and the tumor suppressors p16INK4a and p53

Invasion is generally perceived to be a late event during the progression of human cancer, but to date there are no consistent reports of alterations specifically associated with malignant conversion. We provide evidence that the v-Fos oncogene induces changes in gene expression that render noninvasive normal human diploid fibroblasts highly invasive, without inducing changes in growth factor requirements or anchorage dependence for proliferation. Furthermore, v-Fos-stimulated invasion is independent of the pRb/p16(INK4a) and p53 tumor suppressor pathways and telomerase. We have performed microarray analysis using Affymetrix GeneChips, and the gene expression profile of v-Fos transformed cells supports its role in the regulation of invasion, independent from proliferation. We also demonstrate that invasion, but not proliferation, is dependent on the activity of the up-regulated epidermal growth factor receptor. Taken together, these results indicate that AP-1-directed invasion could precede deregulated proliferation during tumorigenesis and that sustained activation of AP-1 could be the epigenetic event required for conversion of a benign tumor into a malignant one, thereby explaining why many malignant human tumors present without an obvious premalignant hyperproliferative dysplastic lesion.

Suppressions of chronic glomerular injuries and TGF-β1production by HGF in attenuation of murine diabetic nephropathy

Diabetic nephropathy is now the leading cause of end-stage renal diseases, and glomerular sclerotic injury is an initial event that provokes renal dysfunction during processes of diabetes-linked kidney disease. Growing evidence shows that transforming growth factor-β1(TGF-β1) plays a key role in this process, especially in eliciting hypertrophy and matrix overaccumulation. Thus it is important to find a ligand system to antagonize the TGF-β1-mediated pathogenesis under high-glucose conditions. Herein, we provide evidence that hepatocyte growth factor (HGF) targets mesangial cells, suppresses TGF-β1production, and minimizes glomerular sclerotic changes, using streptozotocin-induced diabetic mice. In our murine model, glomerular sclerogenesis (such as tuft area expansion and collagen deposition) progressed between 6 and 10 wk after the induction of hyperglycemia, during a natural course of diabetic disease. Glomerular HGF expression levels in the diabetic kidney transiently increased but then declined below a basal level, with manifestation of glomerular sclerogenesis. When anti-HGF IgG was injected into mice for 2 wk (i.e., from weeks 4 to 6 after onset of hyperglycemia), these glomerular changes were significantly aggravated. When recombinant HGF was injected into the mice for 4 wk (i.e., between 6 and 10 wk following streptozotocin treatment), the progression of glomerular hypertrophy and sclerosis was almost completely inhibited, even though glucose levels remained unchanged (>500 mg/dl). Even more important, HGF repressed TGF-β1production in glomerular mesangial cells even under hyperglycemic conditions both in vitro and in vivo. Consequently, not only albuminuria but also tubulointerstitial fibrogenesis were attenuated by HGF. Overall, HGF therapy inhibited the onset of renal dysfunction in the diabetic mice. On the basis of these findings, we wish to emphasize that HGF plays physiological and therapeutic roles in blocking renal fibrogenesis during a course of diabetic nephropathy.

High expression of Met/hepatocyte growth factor receptor suppresses tumorigenicity in NCI-H1264 lung carcinoma cells

The protein product of c-met proto-oncogene, Met, is a tyrosine kinase receptor for the hepatocyte growth factor (HGF). Met receptor is expressed in normal human bronchial epithelium. In comparison, its expression in squamous cell carcinoma (SQCC) of the lung is markedly decreased in a great majority of cases. To understand further the role of Met receptor overexpression in non-small-cell lung carcinoma, we forced-expressed the full-length met cDNA in the NCI-H1264 (H1264) lung carcinoma cell line with low constitutive expression of this receptor. In vitro studies demonstrated that increased Met expression in H1264 cells resulted in strong inhibition of their ability to form soft agar colonies and in marked suppression of tumorigenicity in the subcutaneous tissue of immune-deficient mice. This is despite inconsistent alteration in the proliferation rate on plastic surfaces. Tumor cells explanted from occasional xenograft tumors formed by the Met-overexpressing H1264 cells also demonstrated marked down-regulation of the receptor protein levels as compared to the transplanted cells. The results suggest that constitutive overexpression of Met receptor may negatively regulate the malignancy of certain human lung cancer cells.

Activation of hepatocyte growth factor-met autocrine loop enhances tumorigenicity in a human lung adenocarcinoma cell line

Hepatocyte growth factor (HGF) is a multifunctional cytokine with effects on the proliferation, motility, and differentiation of cells that express its receptor Met. The co-expression of HGF and Met is common among nonsmall-cell lung cancers, especially adenocarcinoma. However, the biologic consequences of this putative HGF-Met autocrine signaling remain speculative. We have used retroviral gene transduction technique to express high levels of HGF in the NCI-H358 lung adenocarcinoma cells that have functionally active cell surface Met receptor. The activation of autocrine HGF-Met signaling was confirmed by the induction of spontaneous cell scattering activity. Compared to the parent and control cells transduced with the retroviral vector alone, HGF overexpressing H358 cells show enhanced capacity to colonize soft agar medium and to form xenograft tumors when implanted in the subcutaneous tissue of immune-deficient mice. These effects were not accompanied by changes in their growth rate in monolayer culture condition, or in the expression of vascular endothelial growth factor. The tumors formed by HGF overexpressing cells also showed more prominent glandular cell arrangement and functional activity. This report provides the direct in vivo evidence that autocrine HGF-Met signaling plays significant roles in the growth and differentiation of human lung adenocarcinoma cells.

Regulation of P311 expression by Met-hepatocyte growth factor/scatter factor and the ubiquitin/proteasome system

P311 is a mouse cDNA originally identified for its high expression in late-stage embryonic brain and adult cerebellum, hippocampus, and olfactory bulb. The protein product of P311, however, had not been identified previously, and its function remains unknown. We report here that P311 expression is regulated at multiple levels by pathways that control cellular transformation. P311 mRNA expression was decreased sharply in both neural and smooth muscle cells when the cells were transformed by coexpression of the oncogenic tyrosine kinase receptor Met and its ligand hepatocyte growth factor/scatter factor. The P311 mRNA was found to encode an 8-kDa polypeptide that was subject to rapid degradation by the lactacystin-sensitive ubiquitin/proteasome system and an unidentified metalloprotease, resulting in a protein half-life of about 5 min. These data suggest that P311 expression is dramatically decreased by several pathways that regulate cellular growth.

Hepatocyte growth Factor/Scatter factor (HGF/SF) is a regulator of fibronectin splicing in MDCK cells: comparison between the effects of HGF/SF and TGF-beta1 on fibronectin splicing at the EDA region

EDA-containing fibronectin (EDA + FN) is selectively produced under several physiological and pathological conditions requiring tissue remodeling, where cells actively proliferate and migrate. Only a few growth factors, such as transforming growth factor (TGF)-beta1, have been reported to regulate FN splicing at the EDA region. In the present study, we showed for the first time that hepatocyte growth factor/scatter factor (HGF/SF), which is mainly produced by mesenchymal cells and functions as a motogenic and mitogenic factor for epithelial cells, modulates FN splicing at the EDA region in MDCK epithelial cells. HGF/SF treatment increased the ratio of EDA + FN mRNA to mRNA of FN that lacks EDA (EDA - FN) (EDA+/EDA- ratio) more than TGF-beta1 treatment did: at a range from 0.02 to 20 ng/ml, HGF/SF increased the ratio in a dose-dependent manner by up to 2. 1-fold compared with nontreated control, while TGF-beta1 stimulated the EDA+/EDA- ratio by 1.5-fold at the optimum dose of 10 ng/ml. However, TGF-beta1 increased total FN mRNA levels by 3-fold at 10 ng/ml, but HGF/SF did not. We previously demonstrated that fibroblasts cultured at low cell density expressed more EDA + FN than those at high cell density. The same effect of cell density was also observed in MDCK cells. Furthermore, at low cell density, HGF/SF stimulated EDA inclusion into FN mRNA more effectively than did TGF-beta1, whereas at high cell density, TGF-beta1 was more potent than HGF/SF. Simultaneous treatment of cells with HGF/SF and TGF-beta1 synergistically stimulated EDA inclusion into FN mRNA. This stimulation of EDA inclusion into FN mRNA by HGF/SF led to increased EDA + FN protein production and secretion by cells, which was demonstrated by immunoblotting. Thus, our studies have shown that HGF/SF is an enhancer of EDA inclusion into FN mRNA as is TGF-beta1. However, these two factors were different in their effects at low and high cell densities and also in their effects on total FN mRNA levels.