Integrin-Mediated TGFβ Activation Modulates the Tumour Microenvironment

Emerging therapeutic opportunities for integrin inhibitors

Integrins are cell adhesion and signalling proteins crucial to a wide range of biological functions. Effective marketed treatments have successfully targeted integrins αIIbβ3, α4β7/α4β1 and αLβ2 for cardiovascular diseases, inflammatory bowel disease/multiple sclerosis and dry eye disease, respectively. Yet, clinical development of others, notably within the RGD-binding subfamily of αv integrins, including αvβ3, have faced significant challenges in the fields of cancer, ophthalmology and osteoporosis. New inhibitors of the related integrins αvβ6 and αvβ1 have recently come to the fore and are being investigated clinically for the treatment of fibrotic diseases, including idiopathic pulmonary fibrosis and nonalcoholic steatohepatitis. The design of integrin drugs may now be at a turning point, with opportunities to learn from previous clinical trials, to explore new modalities and to incorporate new findings in pharmacological and structural biology. This Review intertwines research from biological, clinical and medicinal chemistry disciplines to discuss historical and current RGD-binding integrin drug discovery, with an emphasis on small-molecule inhibitors of the αv integrins.

Integrins are key signalling molecules that are present on the surface of subsets of cells and are therefore good potential therapeutic targets. In this Review, Hatley and colleagues discuss the development of integrin inhibitors, particularly the challenges in developing inhibitors for integrins that contain an αv-subunit, and suggest how these challenges could be addressed.

Integrin-αV-mediated activation of TGF-β regulates anti-tumour CD8 T cell immunity and response to PD-1 blockade

TGF-β is secreted in the tumour microenvironment in a latent, inactive form bound to latency associated protein and activated by the integrin α_V subunit. The activation of latent TGF-β by cancer-cell-expressed α_V re-shapes the tumour microenvironment, and this could affect patient responses to PD-1-targeting therapy. Here we show, using multiplex immunofluorescence staining in cohorts of anti-PD-1 and anti-PD-L1-treated lung cancer patients, that decreased expression of cancer cell α_V is associated with improved immunotherapy-related, progression-free survival, as well as with an increased density of CD8⁺CD103⁺ tumour-infiltrating lymphocytes. Mechanistically, tumour α_V regulates CD8 T cell recruitment, induces CD103 expression on activated CD8⁺ T cells and promotes their differentiation to granzyme B-producing CD103⁺CD69⁺ resident memory T cells via autocrine TGF-β signalling. Thus, our work provides the underlying principle of targeting cancer cell α_V for more efficient PD-1 checkpoint blockade therapy.

Response to PD-1 checkpoint blockade is unpredictable in lung cancer patients. Here authors show in human lung and mouse tumour models that low or absent α_V integrin expression leads to better tumour growth control by anti-PD-1 via reduced TGF-β activation and hence increased infiltration of anti-tumour CD8⁺ T cells.

The transformation of cancer-associated fibroblasts: Current perspectives on the role of TGF-β in CAF mediated tumor progression and therapeutic resistance

Over the last few years, the Transforming growth factor- β (TGF-β) has been significantly considered as an effective and ubiquitous mediator of cell growth. The cytokine, TGF-β is being increasingly recognized as the most potent inducer of cancer cell initiation, differentiation, migration as well as progression through both the SMAD-dependent and independent pathways. There is growing evidence that supports the role of secretory cytokine TGF-β as a crucial mediator of tumor-stroma crosstalk. Contextually, the CAFs are the prominent component of tumor stroma that helps in tumor progression and onset of chemoresistance. The interplay between the CAFs and the tumor cells through the paracrine signals is facilitated by cytokine TGF-β to induce the malignant progression. Here in this review, we have dissected the most recent advancements in understanding the mechanisms of TGF-β induced CAF activation, their multiple origins, and most importantly their role in conferring chemoresistance. Considering the pivotal role of TGF-β in tumor perogression and associated stemness, it is one the proven clinical targets We have also included the clinical trials going on, targeting the TGF-β and CAFs crosstalk with the tumor cells. Ultimately, we have underscored some of the outstanding issues that must be deciphered with utmost importance to unravel the successful strategies of anti-cancer therapies.

Multifaceted Role of the Transforming Growth Factor β on Effector T Cells and the Implication for CAR-T Cell Therapy

Evading the immune system is one of the hallmarks of cancer. Tumors escape anti-tumor immunity through cell-intrinsic means and the assembly of an immunosuppressive tumor microenvironment. By significantly boosting the host immune system, cancer immunotherapies targeting immune checkpoint receptors (CTLA-4 and PD-1) improved survival in patients even with cancers previously considered rapidly fatal. Nevertheless, an important group of patients is refractory or relapse rapidly. The factors involved in the heterogeneous responses observed are still poorly understood. Other immunotherapeutic approaches are being developed that may widen the options, including adoptive cell therapy using CAR-T cells alone or in combination. Despite impressive results in B cell malignancies, many caveats and unanswered questions remain in other cancers, thus limiting the potential of this approach to treat aggressive diseases. In particular, a complex TME could impair the survival, proliferation, and effector functions of CAR-T cells. Recent reports highlight the potential of targeting TGF-β signaling to improve CAR-T cell therapy. TGF-β is a well-known regulatory cytokine with pleiotropic effects in the TME, including immunosuppression. This review summarizes recent work investigating the potential effects of TGF-β within the TME, with a focus on CAR-T behavior and efficacy. We also discuss several key questions to be addressed to accelerate clinical translation of this approach.

TGF-β as a driver of fibrosis: physiological roles and therapeutic opportunities

Many chronic diseases are marked by fibrosis, which is defined by an abundance of activated fibroblasts and excessive deposition of extracellular matrix, resulting in loss of normal function of the affected organs. The initiation and progression of fibrosis are elaborated by pro-fibrotic cytokines, the most critical of which is transforming growth factor-β1 (TGF-β1). This review focuses on the fibrogenic roles of increased TGF-β activities and underlying signaling mechanisms in the activated fibroblast population and other cell types that contribute to progression of fibrosis. Insight into these roles and mechanisms of TGF-β as a universal driver of fibrosis has stimulated the development of therapeutic interventions to attenuate fibrosis progression, based on interference with TGF-β signaling. Their promise in preclinical and clinical settings will be discussed. © 2021 The Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Mechanosensitive Regulation of Fibrosis

Cells in the human body experience and integrate a wide variety of environmental cues. A growing interest in tissue mechanics in the past four decades has shown that the mechanical properties of tissue drive key biological processes and facilitate disease development. However, tissue stiffness is not only a potent behavioral cue, but also a product of cellular signaling activity. This review explores both roles of tissue stiffness in the context of inflammation and fibrosis, and the important molecular players driving such processes. During inflammation, proinflammatory cytokines upregulate tissue stiffness by increasing hydrostatic pressure, ECM deposition, and ECM remodeling. As the ECM stiffens, cells involved in the immune response employ intricate molecular sensors to probe and alter their mechanical environment, thereby facilitating immune cell recruitment and potentiating the fibrotic phenotype. This powerful feedforward loop raises numerous possibilities for drug development and warrants further investigation into the mechanisms specific to different fibrotic diseases.

GTF2IRD1 overexpression promotes tumor progression and correlates with less CD8+ T cells infiltration in pancreatic cancer

Background: General Transcription Factor II-I Repeat Domain-Containing Protein 1 (GTF2IRD1) is a member of the GTF21 gene family, which encodes a set of multifunctional transcription factors. However, the potential function of GTF2IRD1 in pancreatic cancer (PC) still remains unknown. Study on GTF2IRD1 might provide a new insight into the carcinogenesis and therapeutics of PC.

Methods: In the current study, the clinical significance and potential biological of GTF2IRD1 were evaluated by bioinformatics analysis. The oncogenic role of GTF2IRD1 in PC was also determined using in vitro studies. Possible associations between GTF2IRD1 expression and tumor immunity were analyzed using ESTIMATE algorithm and single-sample Gene Set Enrichment Analysis (ssGSEA).

Results: GTF2IRD1 expression was significantly up-regulated in tumor tissues, and positively associated with higher histologic grade, higher American Joint Committee on Cancer (AJCC) stage, and worse prognosis. Function enrichment analysis demonstrated that GTF2IRD1 may be involved in pancreatic adenocarcinoma pathway, TGF-β signaling pathway, and tumor-infiltrating lymphocyte (TIL) related biological functions, such as T-cell receptor signaling pathway, leukocyte transendothelial migration, resistin as a regulator of inflammation, and regulation of leukocyte-mediated cytotoxicity. Knockdown of GTF2IRD1 expression inhibited cancer cell proliferation, colony formation, and invasion in vitro. ESTIMATE algorithm and ssGSEA demonstrated that GTF2IRD1 expression negatively correlated with the infiltration and anti-tumor activity of TILs, especially for CD8⁺ T cells.

Conclusion: The study demonstrates that GTF2IRD1 overexpression promotes tumor progression and correlates with less CD8⁺ T cells infiltration in PC.

Magnesium Supplementation: Effect on the Expression of Inflammation Genes in Erlich's Tumor

Magnesium supplementation may be beneficial for cancer patients due to its action as a modulator of cell proliferation and metabolism and its anti-inflammatory effect. Tumor metabolism can influence the bioavailability and absorption of nutrients, leading to an increase in the individual's nutritional needs. In this work, the effects of supplementing different dosages of magnesium chloride in mice with solid Ehrlich's tumors were investigated by analyzing their hematological, inflammatory and anthropometric biomarkers. Three dosages of magnesium chloride (MgCl₂) were administered for 28 consecutive days. Animal welfare was assessed according to the criteria stipulated by the National Center for the Replacement, Refinement, and Reduction of Animals in Research (NC3Rs). The inverted grid method was used to analyze muscle strength and fatigue. Difference in expression of the Tumor Necrosis Factor (TNF-α) and the Growth Transformation Factor (TGF-β1) genes was determined by the 2^-ΔCt method. The hematological evaluation consisted of the erythrogram, white blood cell and platelet counts were used for the hematological evaluation and treatment cytotoxicity. Difference in the expression of the TNF-α and TGF-β genes showed that the group that received a high dose of magnesium had a decrease in TNF-α and RNL, an improvement in well-being with a tendency to increase muscle strength and less tumor progression according to the days of treatment. The group that received a low dosage of magnesium had a smaller tumor volume and a more controlled tumor growth according to the days. The group that received an intermediate dosage presented cytotoxicity.

Integrin α2β1 Represents a Prognostic and Predictive Biomarker in Primary Ovarian Cancer

Currently, the same first-line chemotherapy is administered to almost all patients suffering from primary ovarian cancer. The high recurrence rate emphasizes the need for precise drug treatment in primary ovarian cancer. Being crucial in ovarian cancer progression and chemotherapeutic resistance, integrins became promising therapeutic targets. To evaluate its prognostic and predictive value, in the present study, the expression of integrin α2β1 was analyzed immunohistochemically and correlated with the survival data and other therapy-relevant biomarkers. The significant correlation of a high α2β1-expression with the estrogen receptor alpha (ERα; p = 0.035) and epithelial growth factor receptor (EGFR; p = 0.027) was observed. In addition, high α2β1-expression was significantly associated with a low number of tumor-infiltrating immune cells (CD3 intratumoral, p = 0.017; CD3 stromal, p = 0.035; PD-1 intratumoral, p = 0.002; PD-1 stromal, p = 0.049) and the lack of PD-L1 expression (p = 0.005). In Kaplan–Meier survival analysis, patients with a high expression of integrin α2β1 revealed a significant shorter progression-free survival (PFS, p = 0.035) and platinum-free interval (PFI, p = 0.034). In the multivariate Cox regression analysis, integrin α2β1 was confirmed as an independent prognostic factor for both PFS (p = 0.021) and PFI (p = 0.020). Dual expression of integrin α2β1 and the hepatocyte growth factor receptor (HGFR; PFS/PFI, p = 0.004) and CD44v6 (PFS, p = 0.000; PFI, p = 0.001; overall survival [OS], p = 0.025) impaired survival. Integrin α2β1 was established as a prognostic and predictive marker in primary ovarian cancer with the potential to stratify patients for chemotherapy and immunotherapy, and to design new targeted treatment strategies.

Hyaluronan, Transforming Growth Factor β, and Extra Domain A-Fibronectin: A Fibrotic Triad

Significance: Inflammation is a critical aspect of injury repair. Nonresolving inflammation, however, is perpetuated by the local generation of extracellular matrix-derived damage-associated molecular pattern molecules (DAMPs), such as the extra domain A (EDA) isoform of fibronectin and hyaluronic acid (HA) that promote the eventual acquisition of a fibrotic response. DAMPs contribute to the inflammatory environment by engaging Toll-like, integrin, and CD44 receptors while stimulating transforming growth factor (TGF)-β signaling to activate a fibroinflammatory genomic program leading to the development of chronic disease. Recent Advances: Signaling through TLR4, CD44, and the TGF-β pathways impact the amplitude and duration of the innate immune response to endogenous DAMPs synthesized in the context of tissue injury. New evidence indicates that crosstalk among these three networks regulates phase transitions as well as the repertoire of expressed genes in the wound healing program determining, thereby, repair outcomes. Clarifying the molecular mechanisms underlying pathway integration is necessary for the development of novel therapeutics to address the spectrum of fibroproliferative diseases that result from maladaptive tissue repair. Critical Issues: There is an increasing appreciation for the role of DAMPs as causative factors in human fibroinflammatory disease regardless of organ site. Defining the involved intermediates essential for the development of targeted therapies is a daunting effort, however, since various classes of DAMPs activate different direct and indirect signaling pathways. Cooperation between two matrix-derived DAMPs, HA, and the EDA isoform of fibronectin, is discussed in this review as is their synergy with the TGF-β network. This information may identify nodes of signal intersection amenable to therapeutic intervention. Future Directions: Clarifying mechanisms underlying the DAMP/growth factor signaling nexus may provide opportunities to engineer the fibroinflammatory response to injury and, thereby, wound healing outcomes. The identification of shared and unique DAMP/growth factor-activated pathways is critical to the design of optimized tissue repair therapies while preserving the host response to bacterial pathogens.

Integrin ανβ6 Protein Expression and Prognosis in Solid Tumors: A Meta-Analysis

BACKGROUND AND OBJECTIVE

Integrins are a family of adhesion receptor proteins that provide signaling from the extracellular matrix to the cytoplasm. They have been associated with cancer by promoting migration, invasion, metastasis, and survival. ανβ6 integrin is upregulated in several tumors. Here, we evaluate the prognostic impact of ανβ6 integrin protein expression in solid tumors.

METHODS

A systematic search of electronic databases identified publications exploring the effect of ανβ6 integrin on overall survival (OS). Hazard ratios (HRs) were pooled in a meta-analysis using generic inverse variance and random effects modeling. Subgroup analyses were conducted based on tumor site, tumor stage, antibody used for immunohistochemistry (IHC) and method for extraction of the HR. A meta-regression explored the influence of clinical variables on the magnitude of effect of ανβ6 integrins on OS.

RESULTS

Seventeen studies comprising 5795 patients met the inclusion criteria. High ανβ6 integrin expression in tumors was associated with worse OS (HR 1.65, 95% confidence interval [CI] 1.32-2.06; Cochran's Q p < 0.001, I² = 81%). Adverse outcomes were similar in all tumor sites (subgroup difference p = 0.10), with the strongest association between ανβ6 integrins and OS in gastric cancer (HR 2.20, 95% CI 1.71-2.83) and the lowest in head and neck cancer (HR 1.21, 95% CI 0.79-1.83). There was no significant difference between early-stage and metastatic cancer, type of IHC antibodies, and analysis methods.

CONCLUSIONS

High expression of ανβ6 integrins is associated with adverse survival outcome in several tumors. Prospective studies evaluating the prognostic impact of ανβ6 integrin and its role as a therapeutic target are warranted.

In silico transcriptomic mapping of integrins and immune activation in Basal-like and HER2+ breast cancer

PURPOSE

Integrins, transmembrane receptors that mediate cell-extracellular matrix and cell-cell interactions, have been linked to several cancer-associated features. A less explored function of integrins in cancer is their role in leukocyte homing and activation. Understanding their relationship with immune cell infiltrates and immune checkpoints is an area of interest in cancer research.

METHODS

The expression of 33 different integrins was evaluated in relation with breast cancer patient outcome using transcriptomic data (Affymetrix dataset, exploratory cohort) and the METABRIC study (validation cohort). The TIMER online tool was used to assess the association of the identified integrin genes with immune cell infiltration, and the TCGA and METABRIC studies to assess correlations between integrin gene expression and genomic signatures of immune activation.

RESULTS

We identified 7 genes coding for integrin α and β subunits, i.e., ITGA4, ITGB2, ITGAX, ITGB7, ITGAM, ITGAL and ITGA8, which predict a favorable prognosis in Basal-like and HER2+ breast cancers. Their expression positively correlated with the presence of immune cell infiltrates within the tumor (dendritic cells, CD4+ T-cells, neutrophils, CD8+ T-cells and B-cells), with markers of T-cell activation and antigen presentation, and with gene signatures of immune surveillance (cytotoxic T lymphocyte activation and IFN gamma signature). By contrast, we found that genes coding for integrins that predicted a detrimental outcome (IBSP, ITGB3BP, ITGB6, ITGB1 and ITGAV) were not associated with any of these parameters.

CONCLUSIONS

We identified an integrin signature composed of 7 genes with potential to recognize immune infiltrated and activated Basal-like and HER2+ breast cancers with a favorable prognosis.

Targeting TGFβ signal transduction for cancer therapy

Transforming growth factor-β (TGFβ) family members are structurally and functionally related cytokines that have diverse effects on the regulation of cell fate during embryonic development and in the maintenance of adult tissue homeostasis. Dysregulation of TGFβ family signaling can lead to a plethora of developmental disorders and diseases, including cancer, immune dysfunction, and fibrosis. In this review, we focus on TGFβ, a well-characterized family member that has a dichotomous role in cancer progression, acting in early stages as a tumor suppressor and in late stages as a tumor promoter. The functions of TGFβ are not limited to the regulation of proliferation, differentiation, apoptosis, epithelial-mesenchymal transition, and metastasis of cancer cells. Recent reports have related TGFβ to effects on cells that are present in the tumor microenvironment through the stimulation of extracellular matrix deposition, promotion of angiogenesis, and suppression of the anti-tumor immune reaction. The pro-oncogenic roles of TGFβ have attracted considerable attention because their intervention provides a therapeutic approach for cancer patients. However, the critical function of TGFβ in maintaining tissue homeostasis makes targeting TGFβ a challenge. Here, we review the pleiotropic functions of TGFβ in cancer initiation and progression, summarize the recent clinical advancements regarding TGFβ signaling interventions for cancer treatment, and discuss the remaining challenges and opportunities related to targeting this pathway. We provide a perspective on synergistic therapies that combine anti-TGFβ therapy with cytotoxic chemotherapy, targeted therapy, radiotherapy, or immunotherapy.

Overexpression of TGF-β1 induces renal fibrosis and accelerates the decline in kidney function in polycystic kidney disease

Autosomal dominant polycystic kidney disease (ADPKD) is characterized by the presence of numerous fluid-filled cysts, extensive fibrosis, and the progressive decline in kidney function. Transforming growth factor-β1 (TGF-β1), an important mediator for renal fibrosis and chronic kidney disease, is overexpressed by cystic cells compared with normal kidney cells; however, its role in PKD pathogenesis remains undefined. To investigate the effect of TGF-β1 on cyst growth, fibrosis, and disease progression, we overexpressed active TGF-β1 specifically in collecting ducts (CDs) of phenotypic normal (Pkd1^RC/+) and Pkd1^RC/RC mice. In normal mice, CD-specific TGF-β1 overexpression caused tubule dilations by 5 wk of age that were accompanied by increased levels of phosphorylated SMAD3, α-smooth muscle actin, vimentin, and periostin; however, it did not induce overt cyst formation by 20 wk. In Pkd1^RC/RC mice, CD overexpression of TGF-β1 increased cyst epithelial cell proliferation. However, extensive fibrosis limited cyst enlargement and caused contraction of the kidneys, leading to a loss of renal function and a shortened lifespan of the mice. These data demonstrate that TGF-β1-induced fibrosis constrains cyst growth and kidney enlargement and accelerates the decline of renal function, supporting the hypothesis that a combined therapy that inhibits renal cyst growth and fibrosis will be required to effectively treat ADPKD.

Tracking a TGF-β activator in vivo: sensitive PET imaging of αvβ8-integrin with the Ga-68-labeled cyclic RGD octapeptide trimer Ga-68-Triveoctin

Purpose

As a major activator of transforming growth factor β (TGF-β), the RGD receptor αvβ8-integrin is involved in pathogenic processes related to TGF-β dysregulation, such as tumor growth, invasion, and radiochemoresistance, metastasis and tumor cell stemness, as well as epithelial-mesenchymal transition. The novel positron emission tomography (PET) radiopharmaceutical Ga-68-Triveoctin for in vivo mapping of αvβ8-integrin expression might enhance the prognosis of certain tumor entities, as well as support and augment TGF-β-targeted therapeutic approaches.

Methods

Monomeric and trimeric conjugates of cyclo(GLRGDLp(NMe)K(pent-4-ynoic amide)) were synthesized by click chemistry (CuAAC), labeled with Ga-68, and evaluated in MeWo (human melanoma) xenografted SCID mice by means of PET and ex-vivo biodistribution. αvβ8-integrin expression in murine tissues was determined by β8-IHC. A human subject received a single injection of 173 MBq of Ga-68-Triveoctin and underwent 3 subsequent PET/CT scans at 25, 45, and 90 min p.i..

Results

The trimer Ga-68-Triveoctin exhibits a 6.7-fold higher αvβ8-integrin affinity than the monomer (IC₅₀ of 5.7 vs. 38 nM, respectively). Accordingly, biodistribution showed a higher tumor uptake (1.9 vs. 1.0%IA/g, respectively) but a similar baseline upon blockade (0.25%IA/g for both). IHC showed an intermediate β8-expression in the tumor while most organs and tissues were found β8-negative. Low non-target tissue uptakes (< 0.4%IA/g) confirmed a low degree of unspecific binding. Due to its hydrophilicity (log D = − 3.1), Ga-68-Triveoctin is excreted renally and shows favorable tumor/tissue ratios in mice (t/blood: 6.7; t/liver: 6.8; t/muscle: 29). A high kidney uptake in mice (kidney-to-blood and -to-muscle ratios of 126 and 505, respectively) is not reflected by human PET (corresponding values are 15 and 30, respectively), which furthermore showed notable uptakes in coeliac and choroid plexus (SUVmean 6.1 and 9.7, respectively, 90 min p.i.).

Conclusion

Ga-68-Triveoctin enables sensitive in-vivo imaging αvβ8-integrin expression in murine tumor xenografts. PET in a human subject confirmed a favorable biodistribution, underscoring the potential of Ga-68-Triveoctin for mapping of αvβ8-integrin expression in a clinical setting.

Integrin alpha V (ITGAV) expression in esophageal adenocarcinoma is associated with shortened overall-survival

Valid biomarkers for a better prognostic prediction of the clinical course in esophageal adenocarcinoma (EAC) are still not implemented. Integrin alpha V (ITGAV), a transmembrane glycoprotein responsible for cell-to-matrix binding has been found to enhance tumor progression in several tumor entities. The expression pattern and biological role of ITGAV expression in esophageal adenocarcinoma (EAC) has not been analyzed so far. Aim of the study is to evaluate the expression level of ITGAV in a very large collective of EAC and its impact on individual patients´ prognosis. 585 patients with esophageal adenocarcinoma were analyzed immunohistochemically for ITGAV. The data was correlated with clinical, pathological and molecular data (TP53, HER2/neu, c-myc, GATA6, PIK3CA and KRAS). A total of 85 patients (14.3%) out of 585 analyzable tumors showed an ITGAV expression and intratumoral heterogeneity was low. ITGAV expression was correlated with a shortened overall-survival in the patients´ group that underwent primary surgery (p = 0.014) but not in the group of patients that received neoadjuvant treatment before surgery. No correlation between any of the analyzed molecular marker (mutations or amplifications) (TP53, HER2, c-myc, GATA6, PIK3CA and KRAS) and ITGAV expression could be observed. A multivariate cox-regression model was performed which showed tumor stage, lymph node metastasis and ITGAV expression as independent prognostic markers for overall-survival in the group of patients without neoadjuvant treatment. ITGAV expression is correlated with an impaired patient outcome in the group of patients without neoadjuvant therapy and serves as a prognostic factor in EAC.

Click-Chemistry (CuAAC) Trimerization of an αv β6 Integrin Targeting Ga-68-Peptide: Enhanced Contrast for in-Vivo PET Imaging of Human Lung Adenocarcinoma Xenografts

αv β6 Integrin is an epithelial transmembrane protein that recognizes latency-associated peptide (LAP) and primarily activates transforming growth factor beta (TGF-β). It is overexpressed in carcinomas (most notably, pancreatic) and other conditions associated with αv β6 integrin-dependent TGF-β dysregulation, such as fibrosis. We have designed a trimeric Ga-68-labeled TRAP conjugate of the αv β6 -specific cyclic pentapeptide SDM17 (cyclo[RGD-Chg-E]-CONH2 ) to enhance αv β6 integrin affinity as well as target-specific in-vivo uptake. Ga-68-TRAP(SDM17)3 showed a 28-fold higher αv β6 affinity than the corresponding monomer Ga-68-NOTA-SDM17 (IC50 of 0.26 vs. 7.4 nM, respectively), a 13-fold higher IC50 -based selectivity over the related integrin αv β8 (factors of 662 vs. 49), and a threefold higher tumor uptake (2.1 vs. 0.66 %ID/g) in biodistribution experiments with H2009 tumor-bearing SCID mice. The remarkably high tumor/organ ratios (tumor-to-blood 11.2; -to-liver 8.7; -to-pancreas 29.7) enabled high-contrast tumor delineation in PET images. We conclude that Ga-68-TRAP(SDM17)3 holds promise for improved clinical PET diagnostics of carcinomas and fibrosis.

The crosstalk between circular RNAs and the tumor microenvironment in cancer metastasis

Background

Carcinomas are highly heterogeneous with regard to various cancer cells within a tumor microenvironment (TME), which is composed of stromal cells, blood vessels, immunocytes, and modified extracellular matrix.

Focus of the study

Circular RNAs (circRNAs) are non-coding RNAs that are expressed in cancer and stromal cells. They are closely associated with cancer metastasis as their expression in tumor cells directs the latter to migrate to different organs. circRNAs packaged in exosomes might be involved in this process. This is particularly important as the TME acts in tandem with cancer cells to enhance their proliferation and metastatic capability. In this review, we focus on recent studies on the crosstalk between circRNAs and the TME during cancer metastasis.

Conclusion

We particularly emphasize the roles of the interaction between circRNAs and the TME in anoikis resistance, vessel co-option, and local circRNA expression in directing homing of exosome.

Role of αVβ3 in Prostate Cancer: Metastasis Initiator and Important Therapeutic Target

In prostate cancer, distant organ metastasis is the leading cause of patient death. Although the mechanism of malignant tumor metastasis is unclear, studies have confirmed that integrin αVβ3 plays an important role in this process. In prostate cancer, αVβ3 mediates adhesion, invasion, immune escape and neovascularization through interactions with different ligands. Among these ligands and in addition to proteins that are directly related to tumor invasion, other proteins that contain the RGD structure could also bind to αVβ3 and cause a number of biological effects. In this article, we summarized the ligand and downstream proteins related to αVβ3-mediated prostate cancer metastasis as well as some diagnostic and therapeutic measures targeting αVβ3.

Prognostic and Predictive Value of Cadherin 11 for Patients with Gastric Cancer and Its Correlation with Tumor Microenvironment: Results from Microarray Analysis

Gastric cancer is a disease characterized by inflammation, and epithelial-to-mesenchymal transition (EMT) and tumor-associated macrophages (TAMs) both play a vital role in epithelial-driven malignancy. In the present study, we performed an integrated bioinformatics analysis of transcriptome data from multiple databases of gastric cancer patients and worked on a biomarker for evaluating tumor prognosis. We found that cadherin 11 (CDH11) is highly expressed not only in gastric cancer tissues but also in EMT molecular subtypes and metastatic patients. Also, we obtained evidence that CDH11 has a significant correlation with infiltrating immune cells in the tumor microenvironment (TME). Our findings reflected that CDH11 likely plays an important role in tumor immune escape and could provide a prognostic biomarker and potential therapeutic target for patients with gastric cancer.

Integrin Crosstalk Contributes to the Complexity of Signalling and Unpredictable Cancer Cell Fates

Integrins are heterodimeric cell surface receptors composed of α and β subunits that control adhesion, proliferation and gene expression. The integrin heterodimer binding to ligand reorganises the cytoskeletal networks and triggers multiple signalling pathways that can cause changes in cell cycle, proliferation, differentiation, survival and motility. In addition, integrins have been identified as targets for many different diseases, including cancer. Integrin crosstalk is a mechanism by which a change in the expression of a certain integrin subunit or the activation of an integrin heterodimer may interfere with the expression and/or activation of other integrin subunit(s) in the very same cell. Here, we review the evidence for integrin crosstalk in a range of cellular systems, with a particular emphasis on cancer. We describe the molecular mechanisms of integrin crosstalk, the effects of cell fate determination, and the contribution of crosstalk to therapeutic outcomes. Our intention is to raise awareness of integrin crosstalk events such that the contribution of the phenomenon can be taken into account when researching the biological or pathophysiological roles of integrins.

FAM83H overexpression predicts worse prognosis and correlates with less CD8+ T cells infiltration and Ras-PI3K-Akt-mTOR signaling pathway in pancreatic cancer

BACKGROUND

Family with sequence similarity 83 members H (FAM83H) is one member of Family with sequence similarity 83 (FAM83) family, which possess oncogenic properties in several types of cancer. However, the potential function of FAM83H in pancreatic cancer (PC) still remain unknown.

AIM

This study aims to explore the role of FAM83H during pancreatic carcinogenesis and the regulation of immune infiltration in PC.

METHODS

In the current study, the clinical significance and potential biological of FAM83H were evaluated by bioinformatics analysis. Possible associations between FAM83H expression and tumor immunity were analyzed using ESTIMATE algorithm and single-sample gene set enrichment analysis (ssGSEA).

RESULTS

FAM83H expression was significantly upregulated in tumor tissues, and positively associated with higher histologic grade, tumor recurrence, and worse prognosis. FAM83H overexpression is notably associated with KRAS activation. And functional enrichment analysis demonstrated that FAM83H may be involved in positive regulation of cell proliferation and migration, Ras protein signal transduction, regulation of cell-matrix adhesion, epithelial to mesenchymal transition (EMT), TGF-β receptor signaling in EMT, and activated NOTCH transmits signal to the nucleus. ESTIMATE algorithm and ssGSEA demonstrated that FAM83H overexpression suppressed the infiltration and antitumor activity of tumor-infiltrating lymphocytes (TILs), especially for CD8⁺ T cells. Besides, FAM83H overexpression significantly correlated with low expression of TIL-related gene markers (e.g. CD8A, CD8B, CD2, CD3D, and CD3E).

CONCLUSION

The study suggests that FAM83H overexpression predicts poor prognosis and correlates with less CD8⁺ T cells infiltration and Ras-PI3K-Akt-mTOR signaling pathway in PC.

Integrin αvβ8 serves as a Novel Marker of Poor Prognosis in Colon Carcinoma and Regulates Cell Invasiveness through the Activation of TGF-β1

Integrin αvβ8 expressed on tumor cells executes crucial regulatory functions during cell adhesion in the tumor microenvironment and supports the activation of TGF-β1. This study aimed to investigate the expression of integrin αvβ8 and its clinical significance in colon cancer, in addition to its influence on the invasion and migration of cancer cells. Our results showed that integrin αvβ8 was an indicator of progression and poor prognosis in patients with colon cancer. Moreover, integrin αvβ8 significantly promoted the invasion and migration of colon cancer cells by the activation of TGF-β1 and upregulation of metalloproteinase-9. Furthermore, suppression of integrin αvβ8 was found to inhibit the growth of colon cancer in vivo. Our results indicate that integrin αvβ8 promotes tumor invasiveness and the migration of colon cancer through TGF-β1 activation and is a potential prognostic biomarker. This study may provide clues to further understand the manner in which the tumor microenvironment mediates the development of colon cancer and develop strategies for novel therapeutic targets in the prevention and treatment of colon cancer.

TGF-β1 - A truly transforming growth factor in fibrosis and immunity

'Jack of all trades, master of everything' is a fair label for transforming growth factor β1 (TGF-β) - a cytokine that controls our life at many levels. In the adult organism, TGF-β1 is critical for the development and maturation of immune cells, maintains immune tolerance and homeostasis, and regulates various aspects of immune responses. Following acute tissue damages, TGF-β1 becomes a master regulator of the healing process with impacts on about every cell type involved. Divergence from the tight control of TGF-β1 actions, for instance caused by chronic injury, severe trauma, or infection can tip the balance from regulated physiological to excessive pathological repair. This condition of fibrosis is characterized by accumulation and stiffening of collagenous scar tissue which impairs organ functions to the point of failure. Fibrosis and dysregulated immune responses are also a feature of cancer, in which tumor cells escape immune control partly by manipulating TGF-β1 regulation and where immune cells are excluded from the tumor by fibrotic matrix created during the stroma 'healing' response. Despite the obvious potential of TGF-β-signalling therapies, globally targeting TGF-β1 receptor, downstream pathways, or the active growth factor have proven to be extremely difficult if not impossible in systemic treatment regimes. However, TGF-β1 binding to cell receptors requires prior activation from latent complexes that are extracellularly presented on the surface of immune cells or within the extracellular matrix. These different locations have led to some divergence in the field which is often either seen from the perspective of an immunologists or a fibrosis/matrix researcher. Despite these human boundaries, there is considerable overlap between immune and tissue repair cells with respect to latent TGF-β1 presentation and activation. Moreover, the mechanisms and proteins employed by different cells and spatiotemporal control of latent TGF-β1 activation provide specificity that is amenable to drug development. This review aims at synthesizing the knowledge on TGF-β1 extracellular activation in the immune system and in fibrosis to further stimulate cross talk between the two research communities in solving the TGF-β conundrum.