Suppression of OGN in lung myofibroblasts attenuates pulmonary fibrosis by inhibiting integrin αv-mediated TGF-ß/Smad pathway activation.

BACKGROUND: Idiopathic pulmonary fibrosis (IPF) represents a severe and progressive manifestation of idiopathic interstitial pneumonia marked by an uncertain etiology along with an unfavorable prognosis. Osteoglycin (OGN), belonging to the small leucine-rich proteoglycans family, assumes pivotal functions in both tissue formation and damage response. However, the roles and potential mechanisms of OGN in the context of lung fibrosis remain unexplored. METHODS: The assessment of OGN expression levels in fibrotic lungs was conducted across various experimental lung fibrosis mouse models. To elucidate the effects of OGN on the differentiation of lung myofibroblasts, both OGN knockdown and OGN overexpression were employed in vitro. The expression of integrin αv, along with its colocalization with lysosomes and latency-associated peptide (LAP), was monitored in OGN-knockdown lung myofibroblasts. Furthermore, the role of OGN in lung fibrosis was investigated through OGN knockdown utilizing adeno-related virus serotype 6 (AAV6)-mediated delivery. RESULTS: OGN exhibited upregulation in both lungs and myofibroblasts across diverse lung fibrosis mouse models. And laboratory experiments in vitro demonstrated that OGN knockdown inhibited the TGF-ß/Smad signaling pathway in lung myofibroblasts. Conversely, OGN overexpression promoted TGF-ß/Smad pathway in these cells. Mechanistic insights revealed that OGN knockdown facilitated lysosome-mediated degradation of integrin αv while inhibiting its binding to latency-associated peptide (LAP). Remarkably, AAV6-targeted OGN knockdown ameliorated the extent of lung fibrosis in experimental mouse models. CONCLUSION: Our results indicate that inhibiting OGN signaling could serve as a promising therapeutic way for lung fibrosis.

Expression and Clinicopathological Significance of Extracellular Matrix Remodeling Markers in Esophageal Squamous Carcinoma.

Esophageal squamous cell carcinoma (ESCC) is a common malignancy of the gastrointestinal tract with a single therapeutic option and a lack of effective clinical therapeutic biomarkers. Extracellular matrix (ECM) remodeling plays a pro-carcinogenic role in a variety of malignancies, but its role in esophageal squamous carcinoma remains to be elucidated. In this study, we examined the expression levels of ECM remodeling markers in 71 pairs of esophageal squamous carcinoma tissues and normal tissues adjacent to the carcinoma using immunohistochemical staining, and analyzed their relationship with clinicopathological features and prognosis. The results suggested that extracellular matrix remodeling markers (integrin αV, fibronectin, MMP9) were abnormally highly expressed in esophageal squamous carcinoma tissues. There was a statistically significant difference between the positive expression of ECM remodeling and the TNM stage of esophageal squamous carcinoma, and there was no statistically significant correlation with age, gender and carcinoembryonic antigen expression, differentiation degree, T stage, and lymph node metastasis. Overall survival rate and overall survival time were significantly lower in patients with positive ECM remodeling expression, which was an independent risk factor for poor prognosisof esophageal squamous carcinoma.

Humanin activates integrin αV-TGFß axis and leads to glioblastoma progression.

The role of mitochondria peptides in the spreading of glioblastoma remains poorly understood. In this study, we investigated the mechanism underlying intracranial glioblastoma progression. Our findings demonstrate that the mitochondria-derived peptide, humanin, plays a significant role in enhancing glioblastoma progression through the intratumoral activation of the integrin alpha V (ITGAV)-TGF beta (TGFß) signaling axis. In glioblastoma tissues, humanin showed a significant upregulation in the tumor area compared to the corresponding normal region. Utilizing multiple in vitro pharmacological and genetic approaches, we observed that humanin activates the ITGAV pathway, leading to cellular attachment and filopodia formation. This process aids the subsequent migration and invasion of attached glioblastoma cells through intracellular TGFßR signaling activation. In addition, our in vivo orthotopic glioblastoma model provides further support for the pro-tumoral function of humanin. We observed a correlation between poor survival and aggressive invasiveness in the humanin-treated group, with noticeable tumor protrusions and induced angiogenesis compared to the control. Intriguingly, the in vivo effect of humanin on glioblastoma was significantly reduced by the treatment of TGFBR1 inhibitor. To strengthen these findings, public database analysis revealed a significant association between genes in the ITGAV-TGFßR axis and poor prognosis in glioblastoma patients. These results collectively highlight humanin as a pro-tumoral factor, making it a promising biological target for treating glioblastoma.

Integrin-Targeting Strategies for Adenovirus Gene Therapy.

Numerous human adenovirus (AdV) types are endowed with arginine-glycine-aspartic acid (RGD) sequences that enable them to recognize vitronectin-binding (αv) integrins. These RGD-binding cell receptors mediate AdV entry into host cells, a crucial early step in virus infection. Integrin interactions with adenoviruses not only initiate receptor-mediated endocytosis but also facilitate AdV capsid disassembly, a prerequisite for membrane penetration by AdV protein VI. This review discusses fundamental aspects of AdV-host interactions mediated by integrins. Recent efforts to re-engineer AdV vectors and non-viral nanoparticles to target αv integrins for bioimaging and the eradication of cancer cells will also be discussed.

Matrix metalloproteinase-2 inducing COL1A1 synthesis via integrin alpha â ¤ promotes invasion and metastasis of cholangiocarcinoma cells.

INTRODUCTION AND OBJECTIVES: Cholangiocarcinoma (CCA) is characterized by early distant invasion and metastasis, whereas the underlying mechanism is still obscure. Increasing evidence shows that collagen type Ι alpha 1 (COL1A1) is a gene associated with the progression of multiple diseases. Here, we attempted to investigate the role of COL1A1 in CCA. MATERIALS AND METHODS: The expression of COL1A1 between tumor tissues and adjacent normal tissues obtained from CCA patients was detected by Western blot and immunofluorescence, followed by analysis of its clinical significance. Then, the biological effects of COL1A1 overexpression or knockdown on CCA cells were evaluated in vitro and in vivo. Finally, molecular mechanism of COL1A1 in regulating the invasion and metastasis of CCA cells was determined by a series of experiments. RESULTS: COL1A1 expression was significantly higher in CCA pathological tissues than in corresponding adjacent normal tissues. Analysis of 83 CCA patients showed that higher expression of COL1A1 was correlated with poorer patient prognosis. Notably, overexpression or knockdown experiments revealed that COL1A1 contributed to the migration and invasion, as well as epithelial-to-mesenchymal transition (EMT), in CCA cells. Further investigations demonstrated that matrix metalloproteinase-2 (MMP2) promoted COL1A1 upregulation via the integrin alpha Ⅴ pathway, therefore affecting ECM remodelling and inducing EMT in CCA cells. Moreover, COL1A1 expression was positively related to PD-1 and PD-L1 in CCA, and COL1A1 increased PD-L1 expression by activating the NF-κB pathway. CONCLUSIONS: COL1A1 plays an important role in regulating CCA progression and may act as a promising biomarker and therapeutic target for CCA.

Combined inhibition of surface CD51 and γ-secretase-mediated CD51 cleavage improves therapeutic efficacy in experimental metastatic hepatocellular carcinoma.

BACKGROUND & AIMS: Integrin αv (ITGAV, CD51) is regarded as a key component in multiple stages of tumor progression. However, the clinical failure of cilengitide, a specific inhibitor targeting surface CD51, suggests the importance of yet-unknown mechanisms by which CD51 promotes tumor progression. METHODS: In this study, we used several hepatocellular carcinoma (HCC) cell lines and murine hepatoma cell lines. To investigate the role of CD51 on HCC progression, we used a 3D invasion assay and in vivo bioluminescence imaging. We used periostin-knockout transgenic mice to uncover the role of the tumor microenvironment on CD51 cleavage. Moreover, we used several clinically relevant HCC models, including patient-derived organoids and patient-derived xenografts, to evaluate the therapeutic efficacy of cilengitide in combination with the γ-secretase inhibitor LY3039478. RESULTS: We found that CD51 could undergo transmembrane cleavage by γ-secretase to produce a functional intracellular domain (CD51-ICD). The cleaved CD51-ICD facilitated HCC invasion and metastasis by promoting the transcription of oxidative phosphorylation-related genes. Furthermore, we identified cancer-associated fibroblast-derived periostin as the major driver of CD51 cleavage. Lastly, we showed that cilengitide-based therapy led to a dramatic therapeutic effect when supplemented with LY3039478 in both patient-derived organoid and xenograft models. CONCLUSIONS: In summary, we revealed previously unrecognized mechanisms by which CD51 is involved in HCC progression and uncovered the underlying cause of cilengitide treatment failure, as well as providing evidence supporting the translational prospects of combined CD51-targeted therapy in the clinic. IMPACT AND IMPLICATIONS: Integrin αv (CD51) is a widely recognized pro-tumoral molecule that plays a crucial role in various stages of tumor progression, making it a promising therapeutic target. However, despite early promising results, cilengitide, a specific antagonist of CD51, failed in a phase III clinical trial. This prompted further investigation into the underlying mechanisms of CD51's effects. This study reveals that the γ-secretase complex directly cleaves CD51 to produce an intracellular domain (CD51-ICD), which functions as a pro-tumoral transcriptional regulator and can bypass the inhibitory effects of cilengitide by entering the nucleus. Furthermore, the localization of CD51 in the nucleus is significantly associated with the prognosis of patients with HCC. These findings provide a theoretical basis for re-evaluating cilengitide in clinical settings and highlight the importance of identifying a more precise patient subpopulation for future clinical trials targeting CD51.

Prognostic value of integrin αV expression and localization pattern in invasive breast carcinomas.

Invasion of surrounding stroma is an early event in breast cancer metastatic progression, and involves loss of cell polarity, loss of myoepithelial layer, epithelial-mesenchymal transition (EMT) and remodeling of the extracellular matrix (ECM). Integrins are transmembrane receptors responsible for cell-ECM binding, which triggers signals that regulate many aspects of cell behavior and fate. Changes in the expression, localization and pairing of integrins contribute for abnormal responses found in transformed epithelia. We analyzed 345 human breast cancer samples in tissue microarrays (TMA) from cases diagnosed with invasive breast carcinoma to assess the expression and localization pattern of integrin αV and correlation with clinical parameters. Patients with lower levels of integrin αV staining showed reduced cancer specific survival. A subset of cases presented a peripheral staining of integrin αV surrounding tumor cell clusters, possibly matching the remaining myoepithelial layer. Indeed, the majority of ductal carcinoma in situ (DCIS) components found in the TMA presented integrin αV at their periphery, whereas this pattern was mostly lost in invasive components, even in the same sample. The lack of peripheral integrin αV correlated with decreased cancer specific survival. In addition, we observed that the presence of integrin αV in the stroma was an indicative of poor survival and metastatic disease. Consistently, by interrogating publicly available datasets we found that, although patients with higher mRNA levels of integrin αV had increased risk of developing metastasis, high co-expression of integrin αV and a myoepithelial cell marker (MYH11) mRNA levels correlated with better clinical outcomes. Finally, a 3D cell culture model of non-malignant and malignant cells reproduced the integrin αV pattern seen in patient samples. Taken together, our data indicate that both the expression levels of integrin αV and its tissue localization in primary tumors have prognostic value, and thus, could be used to help predict patients at higher risk of developing metastasis.

Machine learning with imaging features to predict the expression of ITGAV, which is a poor prognostic factor derived from transcriptome analysis in pancreatic cancer.

Radiogenomics has attracted attention for predicting the molecular biological characteristics of tumors from clinical images, which are originally a collection of numerical values, such as computed tomography (CT) scans. A prediction model using genetic information is constructed using thousands of image features extracted and calculated from these numerical values. In the present study, RNA sequencing of pancreatic ductal adenocarcinoma (PDAC) tissues from 12 patients was performed to identify genes useful in evaluating clinical pathology, and 107 PDAC samples were immunostained to verify the obtained findings. In addition, radiogenomics analysis of gene expression was performed by machine learning using CT images and constructed prediction models. Bioinformatics analysis of RNA sequencing data identified integrin αV (ITGAV) as being important for clinicopathological factors, such as metastasis and prognosis, and the results of sequencing and immunostaining demonstrated a significant correlation (r=0.625, P=0.039). Notably, the ITGAV high­expression group was associated with a significantly worse prognosis (P=0.005) and recurrence rate (P=0.003) compared with the low­expression group. The ITGAV prediction model showed some detectability (AUC=0.697), and the predicted ITGAV high­expression group was also associated with a worse prognosis (P=0.048). In conclusion, radiogenomics predicted the expression of ITGAV in pancreatic cancer, as well as the prognosis.

Yin Yang 1 regulates ITGAV and ITGB1, contributing to improved prognosis of colorectal cancer.

Yin Yang 1 (YY1) is a multifunctional transcription factor with critical roles in carcinogenesis and metastasis. However, its biological role and clinical impact in colorectal cancer (CRC) remain unclear. In the present study, the function and underlying molecular mechanisms of YY1 in CRC progression were investigated. The immunohistochemistry (IHC) of 143 CRC tissues revealed a significant correlation of low YY1 expression with aggressive clinicopathological features, increased metastasis and recurrence and poor patient survival. Multivariate analysis identified low YY1 expression as an independent poor prognostic factor. Subsequently, the IHC of 66 paired CRC primary tumor and liver metastasis tissues revealed that low YY1 expression in the primary CRC was significantly associated with multiple liver metastases, major hepatectomy, extrahepatic metastasis and poor prognosis. In vitro experiments revealed that YY1 knockdown promoted the migration and invasion of CRC cells. To examine the downstream genes of YY1, a cDNA microarray assay was conducted and the differentially expressed genes between the YY1­knockdown and control cells were compared. Integrin alpha V (ITGAV) and integrin beta 1 (ITGB1) were identified as upregulated hub genes using gene enrichment analysis and protein­protein interaction analyses. Western blotting and IHC confirmed YY1 expression to be negatively correlated with ITGAV and ITGB1 expression. In summary, it was revealed that YY1, as a tumor­suppressor in CRC, contributes to the survival of patients with CRC. Low YY1 expression was associated with the poor prognosis of the patients with primary CRC and liver metastases. YY1 suppressed the expression of ITGAV and ITGB1, and this transcriptional regulation may lead to the suppression of CRC cell migration and invasion.

C1GALT1 high expression is associated with poor survival of patients with pancreatic ductal adenocarcinoma and promotes cell invasiveness through integrin αv.

Pancreatic adenocarcinoma (PDAC) is a leading cause of cancer-related death. Altered glycosylation contributes to tumor progression and chemoresistance in many cancers. C1GALT1 is the key enzyme controlling the elongation of GalNAc-type O-glycosylation. Here we showed that C1GALT1 was overexpressed in 85% (107/126) of PDAC tumors compared with adjacent non-tumor tissues. High expression of C1GALT1 was associated with poor disease-free and overall survival (n = 99). C1GALT1 knockdown using siRNA suppressed cell viability, migration, and invasion as well as increased gemcitabine sensitivity in PDAC cells. In contrast, C1GALT1 overexpression enhanced cell migration and invasion. In subcutaneous and pancreatic orthotopic injection models, C1GALT1 knockdown decreased tumor growth and metastasis of PDAC cells in NOD/SCID mice. Mechanistically, C1GALT1 knockdown dramatically suppressed cell-extracellular matrix (ECM) adhesion, which was associated with decreased phosphorylation of FAK at Y397/Y925 and changes in O-glycans on integrins including the ß1, αv, and α5 subunits. Using functional blocking antibodies, we identified integrin αv as a critical factor in C1GALT1-mediated invasiveness of PDAC cells. In conclusion, this study not only reveals that C1GALT1 could be a potential therapeutic target for PDAC but also provides novel insights into the role of O-glycosylation in the α subunits of integrins.

Exploring Single Nucleotide Polymorphisms in ITGAV for Gastric, Pancreatic and Liver Malignancies: An Approach Towards the Discovery of Biomarker.

BACKGROUND: Integrin αV, encoded by ITGAV gene, is one of the most studied protein subunits, closely associated with liver, pancreatic and stomach cancer progression and metastasis via regulation of angiogenesis. The occurrence of Single Nucleotide Polymorphisms (SNPs) in cancer- associated proteins is a key determinant for varied susceptibility of an individual towards cancer. METHODOLOGY: The study investigated the deleterious effects of these cancer-associated SNPs on the protein's structure, stability and cancer causing potential using an in silico approach. Numerous computational tools were employed that identified the most deleterious cancer-associated SNPs and those to get actively involved in post-translational modifications. The impact of these SNPs on the protein structure, function and stability was also examined. Conclusion and Future Scope: A total 63 non-synonymous SNPs in ITGAV gene were observed to be associated in these three gastrointestinal cancers and among this, 63, 19 were the most deleterious ones. The structural and functional importance of residues altered by most damaging SNPs was analyzed through evolutionary conservation and solvent accessibility. The study also elucidated three-dimensional structures of the 19 most damaging mutants. The analysis of conformational variation identified 5 SNPs (D379Y, G188E, G513V, L950P, and R540L) in integrin αV, which influence the protein's structure. Three calcium binding sites were predicted at residues: D379, G384 and G408 and a peptide binding site at residue: R369 in integrin αV. Therefore, SNPs D379Y, G384C, G408R and R369W have the potential to alter the binding properties of the protein. Screening and characterization of deleterious SNPs could advance novel biomarker discovery and therapeutic development in the future.

Integrated proteomics and phosphoproteomics reveal perturbed regulative pathways in pancreatic ductal adenocarcinoma.

Pancreatic ductal adenocarcinoma (PDAC) has a dismal prognosis largely owing to its inefficient diagnosis, rapid progress, and tenacious drug resistance. Here, we aimed to analyze the expressive patterns of proteins and phosphorylation in PDAC tissue samples and compare them to normal pancreatic tissue to investigate the underlying mechanisms and to reveal potential protein targets for diagnosis and drug development. Liquid chromatography coupled to mass spectrometry (LC-MS) based proteomics and phosphoproteomics analyses were performed using 20 pairs of patient-derived PDAC tissue and normal pancreatic tissue samples. Protein identification and quantification were conducted using MaxQuant software. Bioinformatics analysis was used to retrieve PDAC-relevant pathways and gene ontology (GO) terms. 4985 proteins and 3643 phosphoproteins were identified with high confidence; of these, 322 proteins and 235 phosphoproteins were dysregulated in PDAC. Several pathways, including several extracellular matrix-related pathways, were found to be strongly associated with PDAC. Further, the expression levels of filamin A (FLNA), integrin alpha-V (ITGAV), thymidine phosphorylase (TYMP), medium-chain specific acyl-CoA dehydrogenase, mitochondrial (ACADM), short-chain specific acyl-CoA dehydrogenase, mitochondrial (ACADS), and acetyl-CoA acetyltransferase, mitochondrial (ACAT1) were examined through western blot and immunohistochemistry analysis, and the results confirmed the validity of the proteomics analysis results. These findings provide comprehensive insight into the dysregulated regulative networks in PDAC tissue samples at the protein and phosphorylation levels, and they provide clues for further pathological studies and drug-target development.

Structural impact due to PPQEE deletion in multiple cancer associated protein - Integrin αV: An In silico exploration.

A heterodimeric receptor subunit, Integrin αV, often complexed with Integrin ß3 plays a vital role in cell signaling to regulate angiogenesis and promote cancer progression. The paramount ß-turn formed from pentapeptide residues (PPQEE) in the cytoplasmic domain of Integrin αV was previously reported as crucial for cell signaling and its deletion was proved deleterious for protein's cell membrane adhesion and ligand binding properties. This study revealed conformational changes in the Integrin αV subunit upon deletion of PPQEE residues through in silico structural modelling approach followed by analysis of alteration of binding sites. Human Protein Atlas database helped to identify the association of Integrin αV to the unfavourable prognosis of three gastrointestinal cancers: stomach, liver and pancreatic cancers. Molecular modelling and docking techniques were carried out for the necessary complex formations (wild-type and mutant-type). Further comparison was performed for the complexes. The changes in protein's conformation and stability due to PPQEE deletion were observed in both independent subunit and heterodimer. The most noteworthy conformational shift was the disruption of a transmembrane helix into coil, which accounted for protein's impaired cell membrane adhesion, increased solvent accessibility and decreased stability. The deletion also caused a reduction of beta-turn regions, which disrupted ligand binding in the cytoplasmic domain of Integrin αV subunit. This study emphasized on structural basis of how the deletion of PPQEE residues alters stability, ligand binding and signaling activity of Integrin αV subunit highlighting the importance of these residues in maintenance of protein's native structure.

TAZ target gene ITGAV regulates invasion and feeds back positively on YAP and TAZ in liver cancer cells.

The Hippo pathway effectors yes-associated protein (YAP) and WW domain containing transcription regulator 1 (TAZ/WWTR1) support tumor initiation and progression in various cancer entities including hepatocellular carcinoma (HCC). However, to which extent YAP and TAZ contribute to liver tumorigenesis via common and exclusive molecular mechanisms is poorly understood. RNAinterference (RNAi) experiments illustrate that YAP and TAZ individually support HCC cell viability and migration, while for invasion additive effects were observed. Comprehensive expression profiling revealed partly overlapping YAP/TAZ target genes as well as exclusively regulated genes. Integrin-αV (ITGAV) is a novel TAZ-specific target gene, whose overexpression in human HCC patients correlates with poor clinical outcome, TAZ expression in HCCs, and the abundance of YAP/TAZ target genes. Functionally, ITGAV contributes to actin stress fiber assembly, tumor cell migration and invasion. Perturbation of ITGAV diminishes actin fiber formation and nuclear YAP/TAZ protein levels. We describe a novel Hippo downstream mechanism in HCC cells, which is regulated by TAZ and ITGAV and that feedbacks on YAP/TAZ activity. This mechanism may represent a therapeutic target structure since it contributes to signal amplification of oncogenic YAP/TAZ in hepatocarcinogenesis.

An integrin/MFG-E8 shuttle loads HIV-1 viral-like particles onto follicular dendritic cells in mouse lymph node.

During human immunodeficiency virus-1 (HIV-1) infection lymphoid organ follicular dendritic cells (FDCs) serve as a reservoir for infectious virus and an obstacle to curative therapies. Here, we identify a subset of lymphoid organ sinus lining macrophage (SMs) that provide a cell-cell contact portal, which facilitates the uptake of HIV-1 viral-like particles (VLPs) by FDCs and B cells in mouse lymph node. Central for portal function is the bridging glycoprotein MFG-E8. Using a phosphatidylserine binding domain and an RGD motif, MFG-E8 helps target HIV-1 VLPs to αv integrin bearing SMs. Lack of MFG-E8 or integrin blockade severely limits HIV-1 VLP spread onto FDC networks. Direct SM-FDC virion transfer also depends upon short-lived FDC network abutment, likely triggered by SCSM antigen uptake. This provides a mechanism for rapid FDC loading broadening the opportunity for rare, antigen reactive follicular B cells to acquire antigen, and a means for HIV virions to accumulate on the FDC network.

12N-Substituted Matrinol Derivatives Inhibited the Expression of Fibrogenic Genes via Repressing Integrin/FAK/PI3K/Akt Pathway in Hepatic Stellate Cells.

Twenty new 12N-substituted matrinol derivatives were synthesized and evaluated for their inhibitory effects on collagen α1 (I) (COL1A1) promotor in human hepatic stellate LX-2 cells. The structure-activity relationship (SAR) revealed that introducing a 12N-benzeneaminoacylmethyl substitution might significantly enhance the activity. Compound 8a exhibited the highest inhibitory potency against COL1A1, and its inhibition activity against COL1A1 was further confirmed on both the mRNA and protein levels. It also effectively inhibited the expression of α smooth muscle actin (α-SMA), fibronectin and transforming growth factor ß1 (TGFß1), indicating an extensive inhibitory effect on the expression of fibrogenic genes. The primary mechanism study indicated that it might take action via the Integrin/FAK/PI3K/Akt signaling pathway. The results provided powerful information for further structure optimization, and compound 8a was selected as a novel anti-fibrogenic lead for further investigation.

LncRNA AY promotes hepatocellular carcinoma metastasis by stimulating ITGAV transcription.

Rationale: Tumor metastasis is the main cause for cancer-related death. However, the driving molecules of metastasis remain largely unknown. Here, we aim to identify long non-coding RNAs (lncRNAs) critical for human hepatocellular carcinoma (HCC) metastasis. Methods: Microarrays were used to screen a comprehensive set of lncRNAs with differential expression profiles in sulfatide-treated cells. Mass spectrometry, protein arrays, and RNA pull-down experiments were used to identify proteins that interacted with lncRNA. Epigenetic analysis was used to study lncRNA-mediated regulation mechanisms. Results: We identified lncRNA AY927503 (AY) as a metastasis-associated molecule that was highly expressed in human hepatocellular carcinoma (HCC) and correlated with metastatic events and poor prognosis in patients with HCC. AY promoted HCC cell migration, stemness, 5-fluorouracil resistance, and metastasis in mice. However, knockdown of integrin αV (ITGAV) abolished AY-stimulated migration, cell viability in HCC cells or tube formation. AY strongly promoted ITGAV transcription and αVß3 expression by interacting with the ITGAV promoter specifically and stimulating its activity. AY was identified to interact with histone 1FX (H1FX), but deletion of the central domain of AY (AY∆371-522) abolished H1FX binding and ITGAV promoter stimulation. AY significantly enriched H3K4Me3 and acH3K9/14 but reduced H3K27Me3 and H1FX occupancy on the ITGAV promoter, which remodeled chromatin structures for RNA polymerase II recruitment. Knockdown of H1FX abrogated ITGAV transcription stimulated by AY. Conclusions: Our findings suggested that lncRNA AY promoted HCC metastasis via induction of chromatin modification for ITGAV transcription as a pioneer factor and was a potential molecular signature for metastasis or poor prognosis in patients with HCC.

Imaging the interaction of αv integrin-GFP in osteosarcoma cells with RFP-expressing host stromal cells and tumor-scaffold collagen in the primary and metastatic tumor microenvironment.

Human osteosarcoma 143B cells were previously stably transfected with an αv integrin green flourescent protein (GFP) vector. 143B cells expressing αv integrin-GFP were transplanted orthotopically in the tibia of transgenic nude mice ubiquitously expressing red fluorescent protein (RFP). The primary tumors acquired RFP-expressing stroma and were passaged orthotopically in the tibia in noncolored nude mice, which maintained the RFP stroma. The interaction of αv integrin-GFP expression in 143B cells with RFP-expressing host stromal cells was observed by confocal microscopy using the Olympus FV1000. Collagen fibers were imaged simultaneously in reflectance mode. The RFP-expressing stroma included cancer-associated fibroblasts (CAFs) and tumor-associated macrophages (TAMs) which persisted even 3 weeks after passage to nontransgenic nude mice. CAFs expressing RFP were aligned between collagen fibers and cancer cells expressing αv integrin-GFP. Six weeks after transplantation, pulmonary metastases expressing αv integrin-GFP could be identified. TAMs expressing RFP accompanied metastasized osteosarcoma cells expressing αv integrin-GFP in the lung. The current study demonstrates the importance of αv integrin interaction with stromal elements in osteosarcoma.

SIN3B promotes integrin αV subunit gene transcription and cell migration of hepatocellular carcinoma.

Paired amphipathic helix protein (SIN3B) is a transcription corepressor for many genes. Here we show a different regulation mechanism of integrin αV gene expression by SIN3B in human hepatocellular carcinoma (HCC). We first observed a close relationship between Integrin αV and SIN3B expressions in HCC patients and tumor cell lines with different metastatic potentials. Overexpression of SIN3B significantly accelerated the cell migration rate of SMMC-7721, but failed when integrin αV expression was silenced. Interestingly, SIN3B stimulated integrin αV subunit promoter activity only in the presence of sulfatide. Importantly, SIN3B was identified in the complex with sulfatide by mass spectrometry. Fat blot assay indicated that SIN3B specifically interacted with sulfatide. Molecular modeling suggested that sulfatide induced the conformational change of SIN3B from compacted α-helices to a relaxed ß-sheet in PAH2 domain. The data of immunoprecipitation and ChIP assay indicated that altered SIN3B lost the binding affinity with MAD1 and HDAC2, which reduced the recruitment of HDAC2 on integrin αV gene promoter and prevented the deacetylation of the histone 3. In conclusion, this study demonstrated that SIN3B promoted the transcriptional activation of the integrin αV subunit gene promoter by reducing interaction with HDAC2.

Irisin Mediates Effects on Bone and Fat via αV Integrin Receptors.

Irisin is secreted by muscle, increases with exercise, and mediates certain favorable effects of physical activity. In particular, irisin has been shown to have beneficial effects in adipose tissues, brain, and bone. However, the skeletal response to exercise is less clear, and the receptor for irisin has not been identified. Here we show that irisin binds to proteins of the αV class of integrins, and biophysical studies identify interacting surfaces between irisin and αV/ß5 integrin. Chemical inhibition of the αV integrins blocks signaling and function by irisin in osteocytes and fat cells. Irisin increases both osteocytic survival and production of sclerostin, a local modulator of bone remodeling. Genetic ablation of FNDC5 (or irisin) completely blocks osteocytic osteolysis induced by ovariectomy, preventing bone loss and supporting an important role of irisin in skeletal remodeling. Identification of the irisin receptor should greatly facilitate our understanding of irisin's function in exercise and human health.