Targeting Integrin α3 Blocks ß1 Maturation, Triggers Endoplasmic Reticulum Stress, and Sensitizes Glioblastoma Cells to TRAIL-Mediated Apoptosis.

Glioblastoma (GBM) is a devastating brain cancer for which new effective therapies are urgently needed. GBM, after an initial response to current treatment regimens, develops therapeutic resistance, leading to rapid patient demise. Cancer cells exhibit an inherent elevation of endoplasmic reticulum (ER) stress due to uncontrolled growth and an unfavorable microenvironment, including hypoxia and nutrient deprivation. Cancer cells utilize the unfolded protein response (UPR) to maintain ER homeostasis, and failure of this response promotes cell death. In this study, as integrins are upregulated in cancer, we have evaluated the therapeutic potential of individually targeting all αß1 integrin subunits using RNA interference. We found that GBM cells are uniquely susceptible to silencing of integrin α3. Knockdown of α3-induced proapoptotic markers such as PARP cleavage and caspase 3 and 8 activation. Remarkably, we discovered a non-canonical function for α3 in mediating the maturation of integrin ß1. In its absence, generation of full length ß1 was reduced, immature ß1 accumulated, and the cells underwent elevated ER stress with upregulation of death receptor 5 (DR5) expression. Targeting α3 sensitized TRAIL-resistant GBM cancer cells to TRAIL-mediated apoptosis and led to growth inhibition. Our findings offer key new insights into integrin α3's role in GBM survival via the regulation of ER homeostasis and its value as a therapeutic target.

ITGA3 acts as a purity-independent biomarker of both immunotherapy and chemotherapy resistance in pancreatic cancer: bioinformatics and experimental analysis.

Contribution of integrin superfamily genes to treatment resistance remains uncertain. Genome patterns of thirty integrin superfamily genes were analyzed of using bulk and single-cell RNA sequencing, mutation, copy number, methylation, clinical information, immune cell infiltration, and drug sensitivity data. To select the integrins that are most strongly associated with treatment resistance in pancreatic cancer, a purity-independent RNA regulation network including integrins were constructed using machine learning. The integrin superfamily genes exhibit extensive dysregulated expression, genome alterations, epigenetic modifications, immune cell infiltration, and drug sensitivity, as evidenced by multi-omics data. However, their heterogeneity varies among different cancers. After constructing a three-gene (TMEM80, EIF4EBP1, and ITGA3) purity-independent Cox regression model using machine learning, ITGA3 was identified as a critical integrin subunit gene in pancreatic cancer. ITGA3 is involved in the molecular transformation from the classical to the basal subtype in pancreatic cancer. Elevated ITGA3 expression correlated with a malignant phenotype characterized by higher PD-L1 expression and reduced CD8+ T cell infiltration, resulting in unfavorable outcomes in patients receiving either chemotherapy or immunotherapy. Our findings suggest that ITGA3 is an important integrin in pancreatic cancer, contributing to chemotherapy resistance and immune checkpoint blockade therapy resistance.

Aberrant glycosylation of α3 integrins as diagnostic markers in epithelial ovarian cancer.

BACKGROUND: Glycans are strongly involved in stability and function of integrins (ITG) and tetraspanin protein CD63 and their respective interaction partners as they are dysregulated in the tumorigenic processes. Glycosylation changes is a universal phenomenon of cancer cells. In this study, glycosylation changes in epithelial ovarian cancer (EOC) are explored using tetraspanin and integrin molecules. METHODS: ITG and CD63 were immobilized from 10 EOC and 5 benign ovarian cyst fluid on microtiter wells and traced with 3 glycan binding proteins (STn, WGA, UEA) conjugated on europium nanoparticles. Total protein measurements (ITG & CD63 immunoassays) were also performed. The most promising glycovariant candidates identified were then clinically evaluated on the whole cohort of 77 ovarian cyst fluids. Additional testing was performed in ascites fluid samples of liver cirrhosis (n = 2) and EOC (n = 4). RESULTS: Sialylated Tn antibody based glycovariants of ITGα3 (ITGα3STn) and CD63 (CD63STn) performed better than corresponding protein epitope-based immunoassays, ITGα3IA and CD63IA respectively. Combined ITGα3 based assays (ITGα3IA + ITGα3STn) detected 49 out of 55 malignant & borderline cases without detecting any of the 22 benign and healthy cysts. CONCLUSION: Our findings indicate the potential diagnostic application of ITGα3STn along with total ITGα3IA, which could help reduce the unnecessary surgeries. The results encourage studying further the potential use of these novel assays to detect EOC at earlier clinical stages.

Integrin α3 Mediates Stemness and Invasion of Glioblastoma by Regulating POU3F2.

BACKGROUND: Glioblastoma (GBM) is an aggressive brain tumor. Integrins have been implicated in the malignancy of GBM. A recent study demonstrated that integrin α3 (ITGA3) promoted the invasion of breast cancer cells by regulating transcriptional factor POU3F2. However, whether this also happened in GBM remained unknown. METHODS: Therefore, we explored the relationship between ITGA3 and POU3F2 in GBM. We measured the expression of ITGA3 and POU3F2 in GBM tissues. We generated ITGA3 knockdown and POU3F2 knockdown GBM U87MG cells and the proliferation, migration and invasion, the expression of stemness markers and epithelial to mesenchymal transition (EMT) markers were measured. We transplanted ITGA3 knockdown and POU3F2 knockdown GBM U87MG cells into mice. The mice were treated with anti-ITGA3 antibody. The tumor sizes, the expression of stemness markers and epithelial-to-mesenchymal transition (EMT) markers were measured. RESULTS: Both ITGA3 and POU3F2 were upregulated in GBM tissues. Knocking down ITGA3 resulted in reduced expression of POU3F2. Knocking down ITGA3 and POU3F2 suppressed U87MG cells proliferation, migration and invasion, inhibited the expression of stemness markers and prevented epithelial- to-mesenchymal transition. The transplantation of ITGA3 knockdown and POU3F2 knockdown U87MG cells decreased tumor size. CONCLUSION: Anti-ITGA3 antibody treatment reduced the tumor size. ITGA3 regulates stemness and invasion of glioblastoma through POU3F2.

YY1/ITGA3 pathway may affect trophoblastic cells migration and invasion ability.

Recurrent spontaneous abortion (RSA) is a disturbing pregnancy disorder experienced by ~2.5% of women attempting to conceive. The pathogenesis of RSA is still unclear. Previous findings revealed that transcription factor YIN-YANG 1(YY1) was related to the pathogenesis of RSA by influence trophoblastic cell invasion ability. Present study aimed to investigate more specific molecular mechanism of YY1 playing in trophoblastic cells. In our research, RNA-seq and Chip-seq were used to find significant changed genes between si-YY1(Knock down of YY1) HTR-8/SVneo cells(n = 3) and HTR-8/SVneo cells(n = 3). Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis results suggested that Integrins related pathway maybe necessary to biological functions of trophoblastic cells. Chip-seq dataset analysis results predict YY1 can regulate ITGA3/7 expression by binding to the promoter region of ITGA3/7. Furthermore, results from chip experiment, RT-PCR, Dual-luciferase reporter gene assay showed that YY1 was able to bind to the promoter region of ITGA3 and regulate ITGA3 mRNA and protein expression. However, ITGA7 could not be significant influenced by YY1. Besides, gene silencing experiment, Western blot and Immunofluorescence assay confirmed that both YY1 and ITGA3 can accelerate phosphorylation focal adhesion kinase and affect cytoskeleton formation in HTR-8/SVneo cells. In conclusion, YY1/ITGA3 play a critical role in trophoblast invasion ability by regulating cytoskeleton formation.

Effectiveness of Nano Bioactive Glass Fiber Loaded with Platelet-Rich Plasma on Thermal Wound Healing Process in Rats.

In this study we evaluated the impact of topical application of bioactive glass fibers loaded PRP on a deep seconddegree thermal wound and its healing process sub-streaming molecular pathway of re-epithelialization. Wistar rats were randomly divided into four groups: normal control group, model group (deep second-degree thermal wound), PRP group, and PRP+nanobioactive glass fiber group. After treatment, the changes of wounds were observed daily. H&E staining was used to evaluate the pathological changes and also, qRT-PCR was used to detect the mRNA expression of KGF, IL-1, IL-6, IL-10, TGF-ß, EGF, VEGF, HIF-1α, integrin α3 and integrin ß1 in wound tissues. In the current study, we observed that PRP group and the PRP group basically re-epithelized on the 21st day. The wound healing rates of the PRP+nanobioactive glass fiber group and PRP group at each time point were higher than those in the model group, while there was no significant difference in wound healing rate between the PRP+nanobioactive glass fiber group and PRP group at each time point. H&E staining showed that the pathological scores of skin wound repairing in the PRP+nanobioactive glass fiber group on the 7th, 14th and 21st day were higher than that of in the model group. The qPCR results suggested the mRNA expression of IL-1, IL-6 and IL-10 in the PRP+nanobioactive glass fiber group and the PRP group were lower than those in the untreated group on the 14th day; the expression of VEGF and EGF mRNA were higher on the 3rd day; the mRNA expression of TGF-ß, HIF-1α showed a tendency of increasing first and decreasing then; integrin ß1 mRNA expression increased significantly, which was highest; integrin α3 mRNA expression was higher on day 3rd and 21th, respectively. The PRP+nanobioactive glass fibers and PRP can shorten the wound healing time and improve the healing quality mainly by promoting the wound epithelization through increasing the expression of EGF, VEGF, TGF-ß, HIF-1α, Integrin α3, and meanwhile increasing the release of Integrin ß1 and other mechanisms.

Zebrafish integrin a3b is required for cardiac contractility and cardiomyocyte proliferation.

In cardiac muscle cells, heterodimeric integrin transmembrane receptors are known to serve as mechanotransducers, translating mechanical force to biochemical signaling. However, the roles of many individual integrins have still not been delineated. In this report, we demonstrate that Itga3b is localized to the sarcolemma of cardiomyocytes from 24 to 96 hpf. We further show that heterozygous and homozygous itga3b/bdf mutant embryos display a cardiomyopathy phenotype, with decreased cardiac contractility and reduced cardiomyocyte number. Correspondingly, proliferation of ventricular and atrial cardiomyoctyes and ventricular epicardial cells is decreased in itga3b mutant hearts. The contractile dysfunction of itga3b mutants can be attributed to cardiomyocyte sarcomeric disorganization, including thin myofilaments with blurred and shortened Z-discs. Together, our results reveal that Itga3b localizes to the myocardium sarcolemma, and it is required for cardiac contractility and cardiomyocyte proliferation.

Glomerular endothelial cell-podocyte stresses and crosstalk in structurally normal kidney transplants.

Increased podocyte detachment begins immediately after kidney transplantation and is associated with long-term allograft failure. We hypothesized that cell-specific transcriptional changes in podocytes and glomerular endothelial cells after transplantation would offer mechanistic insights into the podocyte detachment process. To test this, we evaluated cell-specific transcriptional profiles of glomerular endothelial cells and podocytes from 14 patients of their first-year surveillance biopsies with normal histology from low immune risk recipients with no post-transplant complications and compared these to biopsies of 20 healthy living donor controls. Glomerular endothelial cells from these surveillance biopsies were enriched for genes related to fluid shear stress, angiogenesis, and interferon signaling. In podocytes, pathways were enriched for genes in response to growth factor signaling and actin cytoskeletal reorganization but also showed evidence of podocyte stress as indicated by reduced nephrin (adhesion protein) gene expression. In parallel, transcripts coding for proteins required to maintain podocyte adherence to the underlying glomerular basement membrane were downregulated, including the major glomerular podocyte integrin α3 and the actin cytoskeleton-related gene synaptopodin. The reduction in integrin α3 protein expression in surveillance biopsies was confirmed by immunoperoxidase staining. The combined growth and stress response of patient allografts post-transplantation paralleled similar changes in a rodent model of nephrectomy-induced glomerular hypertrophic stress that progress to develop proteinuria and glomerulosclerosis with shortened kidney life span. Thus, even among patients with apparently healthy allografts with no detectable histologic abnormality including alloimmune injury, transcriptomic changes reflecting cell stresses are already set in motion that could drive hypertrophy-associated glomerular disease progression.

miRNA-144-5p/ITGA3 Suppressed the Tumor-Promoting Behaviors of Thyroid Cancer Cells by Downregulating ITGA3.

OBJECTIVE: To ascertain the mechanism of miRNA-144-5p and ITGA3 in thyroid cancer (TC). METHODS: From The Cancer Genome Atlas (TCGA), RNA expression profiles were obtained for the expression analysis of miRNAs and mRNAs in TC. qRT-PCR and western blot were utilized to measure the expression of miRNA-144-5p and ITGA3 at RNA and protein levels, respectively. The association between miRNA-144-5p and ITGA3 was validated by the dual-luciferase assay. CCK-8, scratch healing, transwell, and flow cytometry assays were employed to evaluate tumor-related cell behaviors. RESULTS: Low-expressed miRNA-144-5p and high-expressed ITGA3 were found in TC cells relative to normal cells. miRNA-144-5p expression was positively associated with suppressive effects on proliferative, invasive, and migratory ability of TC cells while negatively associated with cell apoptosis. miRNA-144-5p inhibited ITGA3 expression in TC, and its overexpression remarkably reversed the tumor-promoting effects of overexpressed ITGA3 on the biological functions of TC. CONCLUSION: It is verified in our study that cell growth of TC is inhibited by the miRNA-144-5p/ITGA3 axis, which represents an underlying target for TC. This research proposed a new insight into the strategy of TC treatment.

CD9 and ITGA3 are regulated during HIV-1 infection in macrophages to support viral replication.

Monocytes/macrophages are important target cells for HIV-1. Here, we investigated whether HIV-1 induces changes in the macrophage gene expression profile to support viral replication. We observed that the macrophage gene expression profiles dramatically changed upon HIV-1 infection. The majority of the HIV-1 regulated genes were also differentially expressed in M2a macrophages. The biological functions associated with the HIV-1 induced gene expression profile in macrophages were mainly related to inflammatory responses. CD9 and ITGA3 were among the top genes upregulated upon HIV-1 infection. We showed that these genes support viral replication and that downregulation of these genes decreased HIV-1 replication in macrophages. Here we showed that HIV-1 infection of macrophages induces a gene expression profile that may dampen inflammatory responses. CD9 and ITGA3 were among the top genes regulated by HIV-1 and were shown to support viral production most likely at the level of viral budding and release.

Detection of bladder cancer with aberrantly fucosylated ITGA3.

We describe a simple, non-invasive assay to identify fucosylated-glycoisoform of integrin alpha-3 (ITGA3) directly from unprocessed urine. ITGA3 was detected directly from the urine of bladder cancer (BlCa) (n = 13) and benign prostatic hyperplasia (BPH) (n = 9) patients with the use of lectins coated on europium-doped-nanoparticles (Eu3+-NPs). Lectin Ulex europaeus agglutinin-I (UEA) showed enhanced binding with BlCa-derived ITGA3. The evaluation with individual samples showed that a glycovariant ITGA3-UEA assay could significantly discriminate BlCa from BPH patients (p = 0.007). The detection of aberrantly fucosylated-isoform of ITGA3 from urine can be used to distinguish BlCa from age-matched benign controls in a simple sandwich assay.

Variability within rare cell states enables multiple paths toward drug resistance.

Molecular differences between individual cells can lead to dramatic differences in cell fate, such as death versus survival of cancer cells upon drug treatment. These originating differences remain largely hidden due to difficulties in determining precisely what variable molecular features lead to which cellular fates. Thus, we developed Rewind, a methodology that combines genetic barcoding with RNA fluorescence in situ hybridization to directly capture rare cells that give rise to cellular behaviors of interest. Applying Rewind to BRAFV600E melanoma, we trace drug-resistant cell fates back to single-cell gene expression differences in their drug-naive precursors (initial frequency of ~1:1,000-1:10,000 cells) and relative persistence of MAP kinase signaling soon after drug treatment. Within this rare subpopulation, we uncover a rich substructure in which molecular differences among several distinct subpopulations predict future differences in phenotypic behavior, such as proliferative capacity of distinct resistant clones after drug treatment. Our results reveal hidden, rare-cell variability that underlies a range of latent phenotypic outcomes upon drug exposure.

Zinc-Dependent Regulation of ZEB1 and YAP1 Coactivation Promotes Epithelial-Mesenchymal Transition Plasticity and Metastasis in Pancreatic Cancer.

BACKGROUND: Pancreatic cancer is characterized by extensive metastasis. Epithelial-mesenchymal transition (EMT) plasticity plays a critical role in tumor progression and metastasis by maintaining the transition between EMT and mesenchymal-epithelial transition states. Our aim is to understand the molecular events regulating metastasis and EMT plasticity in pancreatic cancer. METHODS: The interactions between a cancer-promoting zinc transporter ZIP4, a zinc-dependent EMT transcriptional factor ZEB1, a coactivator YAP1, and integrin α3 (ITGA3) were examined in human pancreatic cancer cells, clinical specimens, spontaneous mouse models (KPC and KPCZ) and orthotopic xenografts, and 3-dimensional spheroid and organoid models. Correlations between ZIP4, miR-373, and its downstream targets were assessed by RNA in situ hybridization and immunohistochemical staining. The transcriptional regulation of ZEB1, YAP1, and ITGA3 by ZIP4 was determined by chromatin immunoprecipitation, co-immunoprecipitation, and luciferase reporter assays. RESULTS: The Hippo pathway effector YAP1 is a potent transcriptional coactivator and forms a complex with ZEB1 to activate ITGA3 transcription through the YAP1/transcriptional enhanced associate domain (TEAD) binding sites in human pancreatic cancer cells and KPC-derived mouse cells. ZIP4 upregulated YAP1 expression via activation of miR-373 and inhibition of the YAP1 repressor large tumor suppressor 2 kinase (LATS2). Furthermore, upregulation of ZIP4 promoted EMT plasticity, cell adhesion, spheroid formation, and organogenesis both in human pancreatic cancer cells, 3-dimensional spheroid model, xenograft model, and spontaneous mouse models (KPC and KPCZ) through ZEB1/YAP1-ITGA3 signaling axis. CONCLUSION: We demonstrated that ZIP4 activates ZEB1 and YAP1 through distinct mechanisms. The ZIP4-miR-373-LATS2-ZEB1/YAP1-ITGA3 signaling axis has a significant impact on pancreatic cancer metastasis and EMT plasticity.

Paracoccidioides brasiliensis downmodulates α3 integrin levels in human lung epithelial cells in a TLR2-dependent manner.

Paracoccidioidomycosis (PCM) is the most prevalent systemic mycosis in Latin America and may be caused by the species Paracoccidioides brasiliensis. In the lungs, this fungus interacts with epithelial cells, activating host cell signalling pathways, resulting in the production of inflammatory mediators. This event may be initiated through the activation of Pattern-Recognition Receptors such as Toll-like Receptors (TLRs). By interacting with cell wall components, TLR2 is frequently related to fungal infections. In this work, we show that, after 24 h post-infection with P. brasiliensis, A549 lung epithelial cells presented higher TLR2 levels, which is important for IL-8 secretion. Besides, integrins may also participate in pathogen recognition by host cells. We verified that P. brasiliensis increased α3 integrin levels in A549 cells after 5 h of infection and promoted interaction between this receptor and TLR2. However, after 24 h, surprisingly, we verified a decrease of α3 integrin levels, which was dependent on direct contact between fungi and epithelial cells. Likewise, we observed that TLR2 is important to downmodulate α3 integrin levels after 24 h of infection. Thus, P. brasiliensis can modulate the host inflammatory response by exploiting host cell receptors and cell signalling pathways.

Expression and Prognostic Analyses of ITGA3, ITGA5, and ITGA6 in Head and Neck Squamous Cell Carcinoma.

BACKGROUND The landscape of head and neck cancers has changed with improvements in standard therapy; however, it is necessary to exploit advanced genomic approaches to identify novel diagnostic and prognostic biomarkers for head and neck squamous cell carcinoma (HNSC). ITGA3, ITGA5, and ITGA6, members of the integrin family of proteins, play active roles in cytoskeletal organization and cell migration, proliferation, and survival. However, the expression patterns and prognostic values of ITGA3, ITGA5, and ITGA6 in head and neck squamous cell carcinoma remain unclear. MATERIAL AND METHODS Different expression patterns and prognostic values of ITGA3, ITGA5, and ITGA6 were analyzed in patients with HNSC using various databases, including ONCOMINE, GEPIA, TIMER, HPA, Kaplan-Meier Plotter, GEO, and TCGA. RESULTS Expression levels of ITGA3, ITGA5, and ITGA6 were substantially increased in patients with HNSC. Additionally, higher expression levels of ITGA3, ITGA5, and ITGA6 were associated with worse overall survival in patients with HNSC, and higher levels of ITGA3 correlated with a worse relapse-free survival. CONCLUSIONS ITGA3, ITGA5, and ITGA6 are potential diagnostic and prognostic biomarkers for HNSC. In particular, IGTA5 might be used as a significant independent prognostic factor in this cancer.

Interference with circBC048201 inhibits the proliferation, migration, and invasion of bladder cancer cells through the miR-1184/ITGA3 axis.

The abnormal expression of circular RNA (circRNA) is bound up with the progress of various human cancers. This study aimed to reveal the potential role and mechanism of circBC048201 in the proliferation, migration, and invasion of bladder cancer cells. Quantitative real-time PCR was performed to detect the expression of circBC048201. Cell Counting Kit-8, colony formation, and transwell migration and invasion assays were used to confirm the in vitro functions of circBC048201. Western blot, RNA pull-down, and dual-luciferase reporter gene experiments were performed to study the potential mechanism. circBC048201 was abnormally highly expressed in bladder cancer tissues and cells, and the interference with circBC048201 inhibited bladder cancer cell proliferation, migration, and invasion. From the potential mechanism analysis, our data suggested that circBC048201 and miR-1184, miR-1184 and ITGA3 could bind to each other, and the interference with circBC048201 repressed bladder cancer cell proliferation, migration, and invasion through the miR-1184/ITGA3 axis. In summary, our results showed that circBC048201 was abnormally highly expressed in bladder cancer tissues and cells, and the interference with circBC048201 inhibited the proliferation, migration, and invasion of bladder cancer cells through the miR-1184/ITGA3 axis.

MicroRNA­199a­5p suppresses cell proliferation, migration and invasion by targeting ITGA3 in colorectal cancer.

As a member of the integrin family, integrin α3ß1 (ITGA3) has been linked to intercellular communication and serves an important role in the signaling among cells and the extracellular matrix. MicroRNA (miR)­199a­5p has been demonstrated to be related to the pathogenesis and progression of multiple malignant diseases. However, the biological functions of miR­199a­5p and ITGA3 in colorectal cancer (CRC) have rarely been reported. The aim of the present study was to explore the roles of miR­199a­5p and ITGA3 in CRC. Immunohistochemistry staining and western blotting were applied to detect the protein expression of ITGA3 in CRC tissues and cells. Reverse transcription­quantitative PCR was performed to investigate the expression of miR­199a­5p and ITGA3 mRNA. HCT­116 cells were transfected with miR­199a­5p mimics, mimics control, short hairpin RNA targeting ITGA3, or pcDNA­ITGA3 for the functional experiments. Dual luciferase reporter assay was applied to confirm whether miR­199a­5p targeted the 3' untranslated region (3'UTR) of ITGA3. The MTT, Transwell and wound healing assays were used to evaluate the proliferation, invasion and migration of CRC cells. Immunofluorescence assay was used to monitor the epithelial­mesenchymal transition (EMT) biomarker expression. The results demonstrated downregulation of miR­199a­5p and upregulation of ITGA3 in CRC tissues and cell lines. miR­199a­5p mimics and knockdown of ITGA3 suppressed the proliferation, invasion and migration of CRC cells. Bioinformatics analysis and luciferase reporter assay indicated that miR­199a­5p targeted the 3'UTR of the ITGA3 transcript, and overexpression of ITGA3 reversed the tumor­suppressive effects of miR­199a­5p elevation. In addition, the immunofluorescence assay suggested that miR­199a­5p mimics suppressed the EMT of CRC cells, whereas the overexpression of ITGA3 restored this effect. In conclusion, miR­199a­5p may act as a tumor suppressor by targeting and negatively regulating ITGA3 in CRC.

Novel monoclonal antibody against integrin α3 shows therapeutic potential for ovarian cancer.

Ovarian cancer has a high recurrence rate after platinum-based chemotherapy. To improve the treatment of ovarian cancer and identify ovarian cancer-specific antibodies, we immunized mice with the human ovarian carcinoma cell line, SKOV-3, and generated hybridoma clones. Several rounds of screening yielded 30 monoclonal antibodies (mAbs) with no cross-reactivity to normal cells. Among these mAbs, OV-Ab 30-7 was found to target integrin α3 and upregulate p53 and p21, while stimulating the apoptosis of cancer cells. We further found that binding of integrin α3 by OV-Ab 30-7 impaired laminin-induced focal adhesion kinase phosphorylation. The mAb alone or in combination with carboplatin and paclitaxel inhibited tumor progression and prolonged survival of tumor-bearing mice. Moreover, immunohistochemical staining of ovarian patient specimens revealed higher levels of integrin α3 in cancer cells compared with normal cells. By querying online clinical databases, we found that elevated ITGA3 expression in ovarian cancer is associated with poor prognosis. Taken together, our data suggest that the novel mAb, OV-Ab 30-7, may be considered as a potential therapeutic for ovarian cancer.

Leukocyte Tetraspanin CD53 Restrains α3 Integrin Mobilization and Facilitates Cytoskeletal Remodeling and Transmigration in Mice.

The importance of tetraspanin proteins in regulating migration has been demonstrated in many diverse cellular systems. However, the function of the leukocyte-restricted tetraspanin CD53 remains obscure. We therefore hypothesized that CD53 plays a role in regulating leukocyte recruitment and tested this hypothesis by examining responses of CD53-deficient mice to a range of inflammatory stimuli. Deletion of CD53 significantly reduced neutrophil recruitment to the acutely inflamed peritoneal cavity. Intravital microscopy revealed that in response to several inflammatory and chemotactic stimuli, absence of CD53 had only minor effects on leukocyte rolling and adhesion in postcapillary venules. In contrast, Cd53-/- mice showed a defect in leukocyte transmigration induced by TNF, CXCL1 and CCL2, and a reduced capacity for leukocyte retention on the endothelial surface under shear flow. Comparison of adhesion molecule expression in wild-type and Cd53-/- neutrophils revealed no alteration in expression of ß2 integrins, whereas L-selectin was almost completely absent from Cd53-/- neutrophils. In addition, Cd53-/- neutrophils showed defects in activation-induced cytoskeletal remodeling and translocation to the cell periphery, responses necessary for efficient transendothelial migration, as well as increased α3 integrin expression. These alterations were associated with effects on inflammation, so that in Cd53-/- mice, the onset of neutrophil-dependent serum-induced arthritis was delayed. Together, these findings demonstrate a role for tetraspanin CD53 in promotion of neutrophil transendothelial migration and inflammation, associated with CD53-mediated regulation of L-selectin expression, attachment to the endothelial surface, integrin expression and trafficking, and cytoskeletal function.

Anatomy of a viral entry platform differentially functionalized by integrins α3 and α6.

During cell invasion, human papillomaviruses use large CD151 patches on the cell surface. Here, we studied whether these patches are defined architectures with features for virus binding and/or internalization. Super-resolution microscopy reveals that the patches are assemblies of closely associated nanoclusters of CD151, integrin α3 and integrin α6. Integrin α6 is required for virus attachment and integrin α3 for endocytosis. We propose that CD151 organizes viral entry platforms with different types of integrin clusters for different functionalities. Since numerous viruses use tetraspanin patches, we speculate that this building principle is a blueprint for cell-surface architectures utilized by viral particles.