The COOH-Terminal Globular Domain of Fibrinogen γ Chain Suppresses Angiogenesis and Tumor Growth

Fibrinogen and tumors

Elevated plasma fibrinogen (Fg) levels consistently correlate with an unfavorable prognosis in various tumor patient cohorts. Within the tumor microenvironment, aberrant deposition and expression of Fg have been consistently observed, interacting with multiple cellular receptors and thereby accentuating its role as a regulator of inflammatory processes. Specifically, Fg serves to stimulate and recruit immune cells and pro-inflammatory cytokines, thereby contributing to the promotion of tumor progression. Additionally, Fg and its fragments exhibit dichotomous effects on tumor angiogenesis. Notably, Fg also facilitates tumor migration through both platelet-dependent and platelet-independent mechanisms. Recent studies have illuminated several tumor-related signaling pathways influenced by Fg. This review provides a comprehensive summary of the intricate involvement of Fg in tumor biology, elucidating its multifaceted role and the underlying mechanisms.

Identification of specific prognostic markers for lung squamous cell carcinoma based on tumor progression, immune infiltration, and stem index

Introduction

Lung squamous cell carcinoma (LUSC) is a unique subform of nonsmall cell lung cancer (NSCLC). The lack of specific driver genes as therapeutic targets leads to worse prognoses in patients with LUSC, even with chemotherapy, radiotherapy, or immune checkpoint inhibitors. Furthermore, research on the LUSC-specific prognosis genes is lacking. This study aimed to develop a comprehensive LUSC-specific differentially expressed genes (DEGs) signature for prognosis correlated with tumor progression, immune infiltration,and stem index.

Methods

RNA sequencing data for LUSC and lung adenocarcinoma (LUAD) were extracted from The Cancer Genome Atlas (TCGA) data portal, and DEGs analyses were conducted in TCGA-LUSC and TCGA-LUAD cohorts to identify specific DEGs associated with LUSC. Functional analysis and protein-protein interaction network were performed to annotate the roles of LUSC-specific DEGs and select the top 100 LUSC-specific DEGs. Univariate Cox regression and least absolute shrinkage and selection operator regression analyses were performed to select prognosis-related DEGs.

Results

Overall, 1,604 LUSC-specific DEGs were obtained, and a validated seven-gene signature was constructed comprising FGG, C3, FGA, JUN, CST3, CPSF4, and HIST1H2BH. FGG, C3, FGA, JUN, and CST3 were correlated with poor LUSC prognosis, whereas CPSF4 and HIST1H2BH were potential positive prognosis markers in patients with LUSC. Receiver operating characteristic analysis further confirmed that the genetic profile could accurately estimate the overall survival of LUSC patients. Analysis of immune infiltration demonstrated that the high risk (HR) LUSC patients exhibited accelerated tumor infiltration, relative to low risk (LR) LUSC patients. Molecular expressions of immune checkpoint genes differed significantly between the HR and LR cohorts. A ceRNA network containing 19 lncRNAs, 50 miRNAs, and 7 prognostic DEGs was constructed to demonstrate the prognostic value of novel biomarkers of LUSC-specific DEGs based on tumor progression, stemindex, and immune infiltration. In vitro experimental models confirmed that LUSC-specific DEG FGG expression was significantly higher in tumor cells and correlated with immune tumor progression, immune infiltration, and stem index. In vitro experimental models confirmed that LUSC-specific DEG FGG expression was significantly higher in tumor cells and correlated with immune tumor progression, immune infiltration, and stem index.

Conclusion

Our study demonstrated the potential clinical implication of the 7- DEGs signature for prognosis prediction of LUSC patients based on tumor progression, immune infiltration, and stem index. And the FGG could be an independent prognostic biomarker of LUSC promoting cell proliferation, migration, invasion, THP-1 cell infiltration, and stem cell maintenance.

Spatial transcriptomics reveals the heterogeneity and FGG+CRP+ inflammatory cancer-associated fibroblasts replace islets in pancreatic ductal adenocarcinoma

Background

Understanding the spatial heterogeneity of the tumor microenvironment (TME) in pancreatic cancer (PC) remains challenging.

Methods

In this study, we performed spatial transcriptomics (ST) to investigate the gene expression features across one normal pancreatic tissue, PC tissue, adjacent tumor tissue, and tumor stroma. We divided 18,075 spatial spots into 22 clusters with t-distributed stochastic neighbor embedding based on gene expression profiles. The biological functions and signaling pathways involved in each cluster were analyzed with gene set enrichment analysis.

Results

The results revealed that KRT13+FABP5+ malignant cell subpopulation had keratinization characteristics in the tumor tissue. Fibroblasts from adjacent tumor tissue exhibited a tumor-inhibiting role such as "B-cell activation" and "positive regulation of leukocyte activation." The FGG+CRP+ inflammatory cancer-associated fibroblasts replaced the islets in tumor stroma. During PC progression, the damage to pancreatic structure and function was heavier in the pancreatic exocrine (AMYA2+PRSS1+) than in the endocrine (INS+GCG+).

Conclusion

Our results revealed the spatial heterogeneity of dynamic changes and highlighted the significance of impaired exocrine function in PC.

The emerging roles of exosomes in anti-cancer drug resistance and tumor progression: An insight towards tumor-microenvironment interaction

The tumor microenvironment (TME) is a complex network of cellular organization consisting of fibroblasts, adipocytes, pericytes, immune cells endothelial cells, and extracellular matrix proteins. Besides communicating with each other, tumor cells are also involved in the tumor stroma interaction. Presently, most of the studies have focused on the contribution of TME in supporting tumor growth through intercellular communication by physical contact between the cells or through paracrine signaling cascades of growth factors and cytokines. The crosstalk between the tumor and TME has a pivotal role in the development of anti-cancer drug resistance. Drug resistance, be it against targeted or non-targeted drugs, has emerged as a major hurdle in the successful therapeutic intervention of cancer. Among the several mechanisms involved in the development of the resistance to anti-cancer therapies, exosomes have recently come into the limelight. Exosomes are the nano-sized vesicles, originated from the endolysosomal compartments and have the inherent potential to shuttle diverse biomolecules like proteins, lipids, and nucleic acids to the recipient cells. There are also instances where the pharmacological compounds are transferred between the cells via exosomes. For instance, the transfer of the cargoes from the drug-resistant tumor cells immensely affects the recipient drug-sensitive cells in terms of their proliferation, survival, migration, and drug resistance. In this review, we have discussed multiple aspects of the exosome-mediated bidirectional interplay between tumor and TME. Furthermore, we have also emphasized the contribution of exosomes promoting drug resistance and therapeutic strategies to mitigate the exosome induced drug resistance as well.

Differential Exosomic Proteomic Patterns and Their Influence in Resveratrol Sensitivities of Glioblastoma Cells

Glioblastoma multiforme (GBM) is the commonest primary brain malignancy with extremely poor prognosis. Resveratrol posseses anti-cancer effects, while GBM cells respond differently to it due to certain unknown reason(s). Because the tumor-derived exosomes are supposed to influence chemosensitivity, the exosomic proteins released from resveratrol-sensitive U251 and resveratrol-resistant glioblastoma LN428 cells are profiled before (N/Exo) and after drug treatment (Res/Exo) by label-free liquid chromatography-mass spectrometry (LC-MS). The therapeutic implications of the proteomic findings are estimated by gene ontology enrichment analysis (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG)-based bioinformatic analyses and further elucidated by exosome co-incubating. The results reveal that U251/N/Exo but not U251/Res/Exo enhances resveratrol sensitivity of resveratrol-resistant LN428 cells. The resveratrol sensitive properties of U251 cells are not altered by either LN428/N/Exo or LN428/Res/Exo. U251/N/Exo contains higher levels of chromatin silencing and epidermis development proteins, while U251/Res/Exo has more oxygen transport and G protein-coupled receptor. Both of LN428/N/Exo and LN428/Res/Exo are rich in the proteins related with nucleosome assembly, microtubule-based process and chromatin silencing. In conclusion, U251/N/Exo sensitizes LN428 cells to resveratrol via delivering drug sensitizing signals, suggesting the presence of additional factor(s) that may determine the resveratrol sensitivities of glioblastoma cells.

Exosome: Function and Role in Cancer Metastasis and Drug Resistance

As a kind of nanometric lipidic vesicles, exosomes have been presumed to play a leading role in the regulation of tumor microenvironment through exosomes-mediated transfer of proteins and genetic materials. Tumor-derived exosomes are recognized as a critical determinant of the tumor progression. Intriguingly, some current observations have identified that exosomes are essential for several intercellular exchanges of proteins, messenger RNAs, noncoding RNAs (including long noncoding RNAs and microRNAs) as well as to the process of cancer metastasis and drug resistance. Herein, we review the role of exosomes and their molecular cargos in cancer invasion and metastasis, summarize how they interact with antitumor agents, and highlight their translational implications.

Analysis of haemostasis biomarkers in patients with advanced stage lung cancer during hypofractionated radiotherapy treatment

Objective

To investigate the relationship between changes in inflammatory and coagulatory biomarkers before and after short palliative radiotherapy in patients with advanced stage lung cancer.

Methods

This prospective observational single-centre study enrolled patients with histologically- or cytologically-confirmed lung cancer who were eligible for palliative radiotherapy. Inflammatory and coagulatory biomarkers including complete blood count, D-dimer and fibrinogen levels were evaluated before and after short hypofractionated radiotherapy.

Results

Seventy-two patients with advanced stage lung carcinoma were enrolled in this study. Metastases were associated with an increase in white blood cells, neutrophils and mean platelet volume. Increased volume of the primary tumour had a borderline level of correlation with white blood cell and neutrophil counts. After radiotherapy, white blood cells, neutrophils, haemoglobin and lymphocyte counts were decreased. After radiotherapy, the change in fibrinogen and mean platelet volume were borderline significant.

Conclusion

The levels of inflammatory and coagulatory biomarkers can be used to monitor treatment.

Preoperative peripheral plasma fibrinogen level is an independent prognostic marker in penile cancer

BACKGROUND AND AIM

High levels of peripheral plasma fibrinogen have recently been revealed that related to poor clinical prognosis in various types of malignant tumors. The purpose of this research was to identify the prognostic significance of the preoperative peripheral serum fibrinogen level in patients with penile cell carcinoma.

METHODS

This retrospective research included 72 penile cancer patients with date about their serum fibrinogen value before surgery who undergone either partial or radical penectomy at The 2nd Hospital of Tianjin Medical University between January 2002 to January 2012. They had a mean follow-up of 30.8 months. To determine the factors that were significant in predicting a patient's prognosis, univariate and multivariate analyses were performed according to the Cox proportional hazards regression model.

RESULTS

The 5-year cancer specific survival (CSS) rate was 62.4% of patients with preoperative fibrinogen levels below 340 mg/dl and 41.9% for those with higher levels (p = 0.001). Multivariate analysis revealed that the pathological T stage (p < 0.001), tumor grade (p = 0.036), postoperative chemotherapy (p = 0.041), nodal metastasis(p < 0.001), pathological type (p < 0.001) and fibrinogen (p = 0.023) were independent prognostic factors for survival. Patients with low fibrinogen level (<340mg/dl) had significantly longer CSS and the different survival rate were defined using the log-rank test.

CONCLUSIONS

The high preoperative peripheral serum fibrinogen level was related to poor survival in penile cancer patients. Fibrinogen may serve as a powerful predictor of CSS in penile cancer patients.

Patterns and functional implications of platelets upon tumor "education"

While platelets are traditionally recognized to play a predominant role in hemostasis and thrombosis, increasing evidence verifies its involvement in malignancies. As a component of the tumor microenvironment, platelets influence carcinogenesis, tumor metastasis and chemotherapy efficiency. Platelets status is thus predictable as a hematological biomarker of cancer prognosis and a hot target for therapeutic intervention. On the other hand, the role of circulating tumor cells (CTCs) as an inducer of platelet activation and aggregation has been well acknowledged. The cross-talk between platelets and CTCs is reciprocal on that the CTCs activate platelets while platelets contribute to CTCs' survival and dissemination. This review covers some of the current issues related to the loop between platelets and tumor aggression, including the manners of tumor cells in "educating" platelets and biofunctional alterations of platelets upon tumor "education". We also highlight the potential clinical applications on the interplay between tumors and platelets. Further studies with well-designed prospective multicenter trials may contribute to clinical "liquid biopsy" diagnosis by evaluating the global changes of platelets.

Protein content and functional characteristics of serum-purified exosomes from patients with colorectal cancer revealed by quantitative proteomics

Tumor cells of colorectal cancer (CRC) release exosomes into the circulation. These exosomes can mediate communication between cells and affect various tumor-related processes in their target cells. We present a quantitative proteomics analysis of the exosomes purified from serum of patients with CRC and normal volunteers; data are available via ProteomeXchange with identifier PXD003875. We identified 918 proteins with an overlap of 725 Gene IDs in the Exocarta proteins list. Compared with the serum-purified exosomes (SPEs) of normal volunteers, we found 36 proteins upregulated and 22 proteins downregulated in the SPEs of CRC patients. Bioinformatics analysis revealed that upregulated proteins are involved in processes that modulate the pretumorigenic microenvironment for metastasis. In contrast, differentially expressed proteins (DEPs) that play critical roles in tumor growth and cell survival were principally downregulated. Our study demonstrates that SPEs of CRC patients play a pivotal role in promoting the tumor invasiveness, but have minimal influence on putative alterations in tumor survival or proliferation. According to bioinformatics analysis, we speculate that the protein contents of exosomes might be associated with whether they are involved in premetastatic niche establishment or growth and survival of metastatic tumor cells. This information will be helpful in elucidating the pathophysiological functions of tumor-derived exosomes, and aid in the development of CRC diagnostics and therapeutics.

The role of fibrinogen as a predictor in preoperative chemoradiation for rectal cancer

BACKGROUND

To perform chemoradiotherapy (CRT) effectively, it is clinically beneficial to identify predictors of tumor response after CRT. This study examined the association between plasma fibrinogen level before preoperative CRT and tumor response in advanced rectal cancer.

METHODS

This was a retrospective study of 947 patients who received preoperative CRT followed by curative surgery for primary rectal cancer. We analyzed clinical factors that could be associated with pathologic tumor response in terms of downstaging (ypStage 0-I), primary tumor regression (ypT0-1), and complete response (ypT0N0).

RESULTS

Downstaging was observed in 366 patients (38.6%), primary tumor regression in 187 patients (19.7%) and complete response in 138 patients (14.6%). Multivariate analysis found that pre-CRT carcinoembryonic antigen (CEA) level, fibrinogen level, hemoglobin level, clinical T and N classification, distance from anal verge, and histologic grade were significant predictive factors for downstaging; CEA level, fibrinogen level, and N classification predicted primary tumor regression; CEA level, and fibrinogen level were predictive for complete response.

CONCLUSIONS

This study demonstrated that fibrinogen level was a significant predictor of pathologic tumor response after preoperative CRT.

Binding interaction between (-)-epigallocatechin gallate causes impaired spreading of cancer cells on fibrinogen

Green tea and tea catechins, especially (-)-epigallocatechin gallate (EGCG), have been shown to have various health benefits including anti-cancer, anti-metastasis, and anti-cardiovascular disease effects. Our previous studies demonstrated that three plasma proteins, fibronectin, histidine-rich glycoprotein, and fibrinogen were bound by EGCG, and that one specific domain in fibronectin was responsible for its binding interaction with EGCG. Fibrinogen consists of 6 chains linked by the disulfide bonds of two each of the α-, β-, and γ-chains. The present study examined whether fibrinogen had a specific domain interacting with EGCG. The results of affinity chromatography under reducing conditions demonstrated that each of the α-, β-, and γ-subunit chains of fibrinogen was bound by EGCG. We also demonstrated that several peptides generated by treatment with cyanogen bromide or thermolysin were bound by EGCG. The amino acid sequences analyzed revealed that these peptides included those derived from the α-, β-, and γ-chains of fibrinogen. EGCG inhibited the spreading of mouse metastatic LL2-Lu3 lung cancer cells on the fibrinogen substratum, which suggested an impairment in the interaction between cancer cells and fibrinogen. Since the interaction between cancer cells and fibrinogen plays an important role in metastasis, the present results suggest, at least partially, that EGCG inhibited metastasis in the mouse models reported previously by inhibiting such an interaction.

An integrin binding-defective mutant of insulin-like growth factor-1 (R36E/R37E IGF1) acts as a dominant-negative antagonist of the IGF1 receptor (IGF1R) and suppresses tumorigenesis but still binds to IGF1R

Insulin-like growth factor-1 (IGF1) is a major therapeutic target for cancer. We recently reported that IGF1 directly binds to integrins (αvβ3 and α6β4) and induces ternary complex formation (integrin-IGF1-IGF1 receptor (IGF1R)) and that the integrin binding-defective mutant of IGF1 (R36E/R37E) is defective in signaling and ternary complex formation. These findings predict that R36E/R37E competes with WT IGF1 for binding to IGF1R and inhibits IGF signaling. Here, we described that excess R36E/R37E suppressed cell viability increased by WT IGF1 in vitro in non-transformed cells. We studied the effect of R36E/R37E on viability and tumorigenesis in cancer cell lines. We did not detect an effect of WT IGF1 or R36E/R37E in cancer cells under anchorage-dependent conditions. However, under anchorage-independent conditions, WT IGF1 enhanced cell viability and induced signals, whereas R36E/R37E did not. Notably, excess R36E/R37E suppressed cell viability and signaling induced by WT IGF1 under anchorage-independent conditions. Using cancer cells stably expressing WT IGF1 or R36E/R37E, we determined that R36E/R37E suppressed tumorigenesis in vivo, whereas WT IGF1 markedly enhanced it. R36E/R37E suppressed the binding of WT IGF1 to the cell surface and the subsequent ternary complex formation induced by WT IGF1. R36E/R37E suppressed activation of IGF1R by insulin. WT IGF1, but not R36E/R37E, induced ternary complex formation with the IGF1R/insulin receptor hybrid. These findings suggest that 1) IGF1 induces signals under anchorage-independent conditions and that 2) R36E/R37E acts as a dominant-negative inhibitor of IGF1R (IGF1 decoy). Our results are consistent with a model in which ternary complex formation is critical for IGF signaling.

The role of fibrinogen, fibrin and fibrin(ogen) degradation products (FDPs) in tumor progression

Participation of fibrin, fibrinogen, and their degradation products in pathogenesis and progression of cancer may lead to complications of thromboembolic events. The tumor may be a source of fibrinogen. Fibrinogen inside the tumor is one of the factors of its growth and metastasis. Fibrinogen, fibrin and their degradation products possess proinflammatory activity. They indirectly stimulate endothelium to secrete von Willebrand factor, leading to activation of platelets accompanying neoplastic disorders. Fragments E and D are the end products of fibrin(ogen) degradation and E and DD are the end products of stabilized fibrin. E stimulates proliferation, migration and differentiation of endothelial cells, contributing to tumor vasculature. Increased levels of DD are observed in malignant neoplasms, such as breast, lung, colon and ovary cancers. In breast cancers DD correlates with progression of disease and metastasis. The role of fibrinogen and the products of its degradation in the progression of various tumors is not sufficiently understood.

A dominant-negative FGF1 mutant (the R50E mutant) suppresses tumorigenesis and angiogenesis

Fibroblast growth factor-1 (FGF1) and FGF2 play a critical role in angiogenesis, a formation of new blood vessels from existing blood vessels. Integrins are critically involved in FGF signaling through crosstalk. We previously reported that FGF1 directly binds to integrin αvβ3 and induces FGF receptor-1 (FGFR1)-FGF1-integrin αvβ3 ternary complex. We previously generated an integrin binding defective FGF1 mutant (Arg-50 to Glu, R50E). R50E is defective in inducing ternary complex formation, cell proliferation, and cell migration, and suppresses FGF signaling induced by WT FGF1 (a dominant-negative effect) in vitro. These findings suggest that FGFR and αvβ3 crosstalk through direct integrin binding to FGF, and that R50E acts as an antagonist to FGFR. We studied if R50E suppresses tumorigenesis and angiogenesis. Here we describe that R50E suppressed tumor growth in vivo while WT FGF1 enhanced it using cancer cells that stably express WT FGF1 or R50E. Since R50E did not affect proliferation of cancer cells in vitro, we hypothesized that R50E suppressed tumorigenesis indirectly through suppressing angiogenesis. We thus studied the effect of R50E on angiogenesis in several angiogenesis models. We found that excess R50E suppressed FGF1-induced migration and tube formation of endothelial cells, FGF1-induced angiogenesis in matrigel plug assays, and the outgrowth of cells in aorta ring assays. Excess R50E suppressed FGF1-induced angiogenesis in chick embryo chorioallantoic membrane (CAM) assays. Interestingly, excess R50E suppressed FGF2-induced angiogenesis in CAM assays as well, suggesting that R50E may uniquely suppress signaling from other members of the FGF family. Taken together, our results suggest that R50E suppresses angiogenesis induced by FGF1 or FGF2, and thereby indirectly suppresses tumorigenesis, in addition to its possible direct effect on tumor cell proliferation in vivo. We propose that R50E has potential as an anti-cancer and anti-angiogenesis therapeutic agent (“FGF1 decoy”).

Risk assessment, disease prevention and personalised treatments in breast cancer: is clinically qualified integrative approach in the horizon?

Breast cancer is a multifactorial disease. A spectrum of internal and external factors contributes to the disease promotion such as a genetic predisposition, chronic inflammatory processes, exposure to toxic compounds, abundant stress factors, a shift-worker job, etc. The cumulative effects lead to high incidence of breast cancer in populations worldwide. Breast cancer in the USA is currently registered with the highest incidence rates amongst all cancer related patient cohorts. Currently applied diagnostic approaches are frequently unable to recognise early stages in tumour development that impairs individual outcomes. Early diagnosis has been demonstrated to be highly beneficial for significantly enhanced therapy efficacy and possibly full recovery. Actual paper shows that the elaboration of an integrative diagnostic approach combining several levels of examinations creates a robust platform for the reliable risk assessment, targeted preventive measures and more effective treatments tailored to the person in the overall task of breast cancer management. The levels of examinations are proposed, and innovative technological approaches are described in the paper. The absolute necessity to create individual patient profiles and extended medical records is justified for the utilising by routine medical services. Expert recommendations are provided to promote further developments in the field.

Effects of initial cell density and hydrodynamic culture on osteogenic activity of tissue-engineered bone grafts

This study aimed to study the effects of initial cell density and in vitro culture method on the construction of tissue-engineered bone grafts and osteogenic activities. Human mesenchymal stem cells (hMSCs) were seeded onto cubic scaffolds prepared from demineralized bone matrix (DBM) by three methods - static, hydrodynamic, or fibrin hydrogel-assisted seeding. The resulting cell-scaffold constructs were cultured in vitro by static flask culture or hydrodynamic culture. The initial cell density and the subsequent in vitro proliferation and alkaline phosphate activities of the constructs were analyzed. The constructs were also subcutaneously implanted in nude mice to examine their in vivo osteogenic activities. Hydrogel-assisted seeding gave the highest seeding efficiency, followed by hydrodynamic and conventional static seeding. During in vitro culture, hydrodynamic culture produced higher plateau cell densities, alkaline phosphatase (ALP) activities, and extracellular matrix production than static culture. After subcutaneous implantation in nude mice, the implants prepared by the combination of hydrogel-assisted seeding and hydrodynamic culture produced higher wet weight and bone mineral density than implants prepared by other methods. The results suggest that the hydrogel-assisted seeding can substantially increase the initial seed cell density in scaffolds. Subsequent hydrodynamic culture can promote the proliferation and osteoblastic differentiation of the seeded cells. Correspondingly, bone grafts produced by the combination of these two methods achieved the highest osteogenic activity among the three methods employed.

Insulin-like growth factor (IGF) signaling requires αvβ3-IGF1-IGF type 1 receptor (IGF1R) ternary complex formation in anchorage independence, and the complex formation does not require IGF1R and Src activation

Integrin αvβ3 plays a role in insulin-like growth factor 1 (IGF1) signaling (integrin-IGF1 receptor (IGF1R) cross-talk) in non-transformed cells in anchorage-dependent conditions. We reported previously that IGF1 directly binds to αvβ3 and induces αvβ3-IGF1-IGF1R ternary complex formation in these conditions. The integrin-binding defective IGF1 mutant (R36E/R37E) is defective in inducing ternary complex formation and IGF signaling, whereas it still binds to IGF1R. We studied if IGF1 can induce signaling in anchorage-independent conditions in transformed Chinese hamster ovary cells that express αvβ3 (β3-CHO) cells. Here we describe that IGF1 signals were more clearly detectable in anchorage-independent conditions (polyHEMA-coated plates) than in anchorage-dependent conditions. This suggests that IGF signaling is masked by signals from cell-matrix interaction in anchorage-dependent conditions. IGF signaling required αvβ3 expression, and R36E/R37E was defective in inducing signals in polyHEMA-coated plates. These results suggest that αvβ3-IGF1 interaction, not αvβ3-extracellular matrix interaction, is essential for IGF signaling. Inhibitors of IGF1R, Src, AKT, and ERK1/2 did not suppress αvβ3-IGF-IGF1R ternary complex formation, suggesting that activation of these kinases are not required for ternary complex formation. Also, mutations of the β3 cytoplasmic tail (Y747F and Y759F) that block β3 tyrosine phosphorylation did not affect IGF1R phosphorylation or AKT activation. We propose a model in which IGF1 binding to IGF1R induces recruitment of integrin αvβ3 to the IGF-IGF1R complex and then β3 and IGF1R are phosphorylated. It is likely that αvβ3 should be together with the IGF1-IGF1R complex for triggering IGF signaling.

Analysis of the urinary peptidome associated with Helicobacter pylori infection

AIM: To investigate the relationship between urinary peptide changes and Helicobacter pylori (H. pylori) infection using urinary peptidome profiling.

METHODS: The study was performed in volunteers (n = 137) who gave informed consent. Urinary peptides were enriched by magnetic beads based weak cation exchange chromatography and spectrums acquired by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry (MS). ClinProTools bioinformatics software was used for statistical analysis and the recognition of peptide patterns. The marker peptides were identified by LTQ Obitrap XL tandem MS.

RESULTS: Approximately 50 proteins or peptides which loaded onto the magnetic beads were detected by MALDI-TOF MS. By optimizing the parameters of the model, the Genetic Algorithm model had good recognition capability (97%) and positive predictive value (94%). Based on the model, 2 markers with molecular masses of 6788 and 1912 Da were found that differentiated between H. pylori positive and negative volunteers. The m/z 1912 sequence was parsed as SKQFTSSTSYNRGDSTF. The peptide was identified as isoform 1 of the fibrinogen α chain precursor, whose concentration in urine was markedly higher in H. pylori infected volunteers than in H. pylori non-infected ones.

CONCLUSION: The appearance of urinary fibrinogen degradation products is caused by an active H. pylori-induced process.

Hyperfibrinogenemia after preoperative chemoradiotherapy predicts poor response and poor prognosis in rectal cancer

PURPOSE

Although hyperfibrinogenemia has been reported in patients with colorectal cancer, neither its clinical implications nor the effect of chemoradiotherapy (CRT) on the fibrinogen levels have been fully investigated. We investigated the clinical significance of pre- and post-CRT fibrinogen levels in patients with rectal cancer.

METHODS

The medical records of 82 patients with rectal cancer, who had received CRT followed by surgical resection, were retrospectively reviewed. The correlation between the clinicopathological variables and the pre- and post-CRT plasma fibrinogen levels, and that between the changes of fibrinogen, C-reactive protein (CRP), or carcinoembryonic antigen (CEA) levels after CRT and the pathological tumor regression grading was analyzed. Furthermore, the impact of post-CRT fibrinogen levels on the prognosis of these patients was assessed.

RESULTS

Plasma fibrinogen markedly decreased after CRT. The post-CRT fibrinogen level significantly correlated with lymphatic invasion, venous invasion, tumor size, depth of invasion, and the pathological tumor regression grading. The CRT-induced pathological tumor regression grading well correlated with the decrease of fibrinogen level, but not with that of CRP or CEA. Furthermore, patients with high post-CRT fibrinogen had significantly shorter disease-free survival.

CONCLUSIONS

Reduction of plasma fibrinogen induced by CRT should be a promising biomarker for evaluating the efficacy of CRT in rectal cancer patients.

Fibrinogen-gamma C-terminal fragments induce endothelial barrier dysfunction and microvascular leak via integrin-mediated and RhoA-dependent mechanism

OBJECTIVES

The purposes of this study were to characterize the direct effect of the C-terminal fragment of fibrinogen gamma chain (gammaC) on microvascular endothelial permeability and to examine its molecular mechanism of action.

METHODS AND RESULTS

Intravital microscopy was performed to measure albumin extravasation in intact mesenteric microvasculature, followed by quantification of hydraulic conductivity in single perfused microvessels. Transendothelial electric resistance was measured in microvascular endothelial cells in combination with immunoblotting and immunocytochemistry. The results show that gammaC induced time- and concentration-dependent increases in protein transvascular flux and water permeability and decreases in endothelial barrier function, coupled with Rho GTPase activation, myosin light chain phosphorylation, and stress fiber formation. Depletion of RhoA via siRNA knockdown or pharmacological inhibition of RhoA signaling attenuated gammaC-induced barrier dysfunction. Imaging analyses demonstrated binding of gammaC to endothelial cells; the interaction was inhibited during blockage of the alphavbeta3 integrin. Furthermore, in vivo experiments showed that the microvascular leak response to gammaC was attenuated in integrin beta3(-/-) animals.

CONCLUSION

Fibrinogen-gamma C terminus directly interacts with the microvascular endothelium causing fluid and protein leak. The endothelial response to gammaC involves an integrin receptor-mediated RhoA-dependent signaling pathway that leads to paracellular hyperpermeability.

Effect of covalent antithrombin-heparin complex on developmental mechanisms in the lung

We have developed a potent antithrombin (AT)-heparin conjugate (ATH) that is retained in the lung to prevent pulmonary thrombosis associated with respiratory distress in premature newborns. During continuing maturation, pulmonary angiogenesis in premature infants would be a crucial process in lung development. A naturally occurring latent form of antithrombin (L-AT) has antiangiogenic effects on lung vascularization. However, impact of latent ATH (L-ATH) on developing lung vascularization is unknown. Thus, effects of L-AT and L-ATH on fetal murine lung development were compared. Lung buds from embryonic day 11.5 (E11.5) Tie2-LacZ mouse embryos were incubated in DMEM plus FBS supplemented with PBS, AT, L-AT, heparin, ATH, or L-ATH. Vasculature of cultured explants was quantified by X-galactosidase staining. RNA was analyzed with murine gene probes for angiopoietin (Ang)-1, Ang-2, fibroblast growth factor 2 (FGF2), platelet endothelial cell adhesion molecule (PECAM), and vascular endothelial growth factor (VEGF). FGF2-supplemented medium was used to test contribution to effects of L-AT and L-ATH on angiogenesis. Epithelial branching morphogenesis was inhibited by L-AT (P = 0.003) and heparin (P < 0.001). L-AT and heparin decreased relative vascular area compared with PBS, ATH, and L-ATH. Expressions of all genes studied were downregulated by L-AT. However, L-AT and L-ATH inhibited branching morphogenesis and vasculature with added FGF2. These findings indicate that covalent linkage of AT to heparin negates disruptive effects of these moieties on lung morphology, vascularization, and growth factor gene expression. ATH may have enhanced safety as an anticoagulant during vascular development.

Structural basis for distinctive recognition of fibrinogen gammaC peptide by the platelet integrin alphaIIbbeta3

Hemostasis and thrombosis (blood clotting) involve fibrinogen binding to integrin α_IIbβ₃ on platelets, resulting in platelet aggregation. α_vβ₃ binds fibrinogen via an Arg-Asp-Gly (RGD) motif in fibrinogen's α subunit. α_IIbβ₃ also binds to fibrinogen; however, it does so via an unstructured RGD-lacking C-terminal region of the γ subunit (γC peptide). These distinct modes of fibrinogen binding enable α_IIbβ₃ and α_vβ₃ to function cooperatively in hemostasis. In this study, crystal structures reveal the integrin α_IIbβ₃–γC peptide interface, and, for comparison, integrin α_IIbβ₃ bound to a lamprey γC primordial RGD motif. Compared with RGD, the GAKQAGDV motif in γC adopts a different backbone configuration and binds over a more extended region. The integrin metal ion–dependent adhesion site (MIDAS) Mg²⁺ ion binds the γC Asp side chain. The adjacent to MIDAS (ADMIDAS) Ca²⁺ ion binds the γC C terminus, revealing a contribution for ADMIDAS in ligand binding. Structural data from this natively disordered γC peptide enhances our understanding of the involvement of γC peptide and integrin α_IIbβ₃ in hemostasis and thrombosis.

Direct binding of integrin alphavbeta3 to FGF1 plays a role in FGF1 signaling

Integrins play a role in fibroblast growth factor (FGF) signaling through cross-talk with FGF receptors (FGFRs), but the mechanism underlying the cross-talk is unknown. We discovered that FGF1 directly bound to soluble and cell-surface integrin alphavbeta3 (K(D) about 1 microm). Antagonists to alphavbeta3 (monoclonal antibody 7E3 and cyclic RGDfV) blocked this interaction. alphavbeta3 was the predominant, if not the only, integrin that bound to FGF1, because FGF1 bound only weakly to several beta1 integrins tested. We presented evidence that the CYDMKTTC sequence (the specificity loop) within the ligand-binding site of beta3 plays a role in FGF1 binding. We found that the integrin-binding site of FGF1 overlaps with the heparin-binding site but is distinct from the FGFR-binding site using docking simulation and mutagenesis. We identified an FGF1 mutant (R50E) that was defective in integrin binding but still bound to heparin and FGFR. R50E was defective in inducing DNA synthesis, cell proliferation, cell migration, and chemotaxis, suggesting that the direct integrin binding to FGF1 is critical for FGF signaling. Nevertheless, R50E induced phosphorylation of FGFR1 and FRS2alpha and activation of AKT and ERK1/2. These results suggest that the defect in R50E in FGF signaling is not in the initial activation of FGF signaling pathway components, but in the later steps in FGF signaling. We propose that R50E is a useful tool to identify the role of integrins in FGF signaling.

Impact of the non-cellular tumor microenvironment on metastasis: potential therapeutic and imaging opportunities

Evidence is accumulating that the malignant phenotype of a given tumor is dependent not only on the intrinsic characteristics of tumor cells, but also on the cooperative interactions of non-neoplastic cells, soluble secreted factors and the non-cellular solid-state ECM network that comprise the tumor microenvironment. Given the ability of the tumor microenvironment to regulate the cellular phenotype, recent efforts have focused on understanding the molecular mechanisms by which cells sense, assimilate, interpret, and ultimately respond to their immediate surroundings. Exciting new studies are beginning to unravel the complex interactions between the numerous cell types and regulatory factors within the tumor microenvironment that function cooperatively to control tumor cell invasion and metastasis. Here, we will focus on studies concerning a common theme, which is the central importance of the non-cellular solid-state compartment as a master regulator of the malignant phenotype. We will highlight the non-cellular solid-state compartment as a relatively untapped source of therapeutic and imaging targets and how cellular interactions with these targets may regulate tumor metastasis.