FLRT2 prevents endothelial cell senescence and vascular aging by regulating the ITGB4/mTORC2/p53 signaling pathway.

The roles of fibronectin leucine-rich transmembrane protein 2 (FLRT2) in physiological and pathological processes are not well known. Here, we identify a potentially novel function of FLRT2 in preventing endothelial cell senescence and vascular aging. We found that FLRT2 expression was lower in cultured senescent endothelial cells as well as in aged rat and human vascular tissues. FLRT2 mediated endothelial cell senescence via the mTOR complex 2, AKT, and p53 signaling pathway in human endothelial cells. We uncovered that FLRT2 directly associated with integrin subunit beta 4 (ITGB4) and thereby promoted ITGB4 phosphorylation, while inhibition of ITGB4 substantially mitigated the induction of senescence triggered by FLRT2 depletion. Importantly, FLRT2 silencing in mice promoted vascular aging, and overexpression of FLRT2 rescued a premature vascular aging phenotype. Therefore, we propose that FLRT2 could be targeted therapeutically to prevent senescence-associated vascular aging.

MDFI promotes the proliferation and tolerance to chemotherapy of colorectal cancer cells by binding ITGB4/LAMB3 to activate the AKT signaling pathway.

Colorectal cancer (CRC) is one of the most lethal cancers. Single-cell RNA sequencing (scRNA-seq) and protein-protein interactions (PPIs) have enabled the systematic study of CRC. In our research, the activation of the AKT pathway in CRC was analyzed by KEGG using single-cell sequencing data from the GSE144735 dataset. The correlation and PPIs of MDFI and ITGB4/LAMB3 were examined. The results were verified in the TCGA and CCLE and further tested by coimmunoprecipitation experiments. The effect of MDFI on the AKT pathway via ITGB4/LAMB3 was validated by knockdown and lentiviral overexpression experiments. The effect of MDFI on oxaliplatin/fluorouracil sensitivity was probed by colony formation assay and CCK8 assay. We discovered that MDFI was positively associated with ITGB4/LAMB3. In addition, MDFI was negatively associated with oxaliplatin/fluorouracil sensitivity. MDFI upregulated the AKT pathway by directly interacting with LAMB3 and ITGB4 in CRC cells, and enhanced the proliferation of CRC cells via the AKT pathway. Finally, MDFI reduced the sensitivity of CRC cells to oxaliplatin and fluorouracil. In conclusion, MDFI promotes the proliferation and tolerance to chemotherapy of colorectal cancer cells, partially through the activation of the AKT signaling pathway by the binding to ITGB4/LAMB3. Our findings provide a possible molecular target for CRC therapy.

ING3 inhibits the malignant progression of lung adenocarcinoma by negatively regulating ITGB4 expression to inactivate Src/FAK signaling.

Lung adenocarcinoma (LUAD) is the most commonly diagnosed subtype of lung cancer worldwide. Inhibitor of growth 3 (ING3) serves as a tumor suppressor in many cancers. This study aimed to elucidate the role of ING3 in the progression of LUAD and investigate the underlying mechanism related to integrin ß4 (ITGB4) and Src/focal adhesion kinase (FAK) signaling. ING3 expression in LUAD tissues and the correlation between ING3 expression and prognosis were analyzed by bioinformatics databases. After evaluating ING3 expression in LUAD cells, ING3 was overexpressed to assess the proliferation, cell cycle arrest, migration and invasion of LUAD cells. Then, ITGB4 was upregulated to observe the changes of malignant activities in ING3-overexpressed LUAD cells. The transplantation tumor model of NCI-H1975 cells in nude mice was established to analyze the antineoplastic effect of ING3 upregulation in vivo. Downregulated ING3 expression was observed in LUAD tissues and cells and lower ING3 expression predicated the poor prognosis. ING3 upregulation restrained the proliferation, migration, invasion and induced the cell cycle arrest of NCI-H1975 cells. Additionally, ITGB4 expression was negatively correlated with ING3 expression in LUAD tissue. ING3 led to reduced expression of ITGB4, Src and p-FAK. Moreover, ITGB4 overexpression alleviated the effects of ING3 upregulation on the malignant biological properties of LUAD cells. It could be also found that ING3 upregulation limited the tumor volume, decreased the expression of ITGB4, Src and p-FAK, which was restored by ITGB4 overexpression. Collectively, ING3 inhibited the malignant progression of LUAD by negatively regulating ITGB4 expression to inactivate Src/FAK signaling.

ITGB4 upregulation is associated with progression of lower grade glioma.

Gliomas originating in the neuroepithelium account for about 80% of brain malignancies and are the most common cancer of the central nervous system. Clinical management of gliomas remains challenging despite significant advances in comprehensive therapies, including radiotherapy, chemotherapy, and surgery. The ITGB4 (Integrin subunit beta 4) gene encodes a receptor for laminins and its upregulation in tumor tissues is associated with poor prognosis. However, its role in glioma is not well understood. First, we performed a pan cancer analysis of ITGB4 expression in The Cancer Genome Atlas (TCGA) dataset. Survival analysis was done on Chinese Glioma Genome Atlas (CGGA) and TCGA. Immunohistochemistry was then used to validate the expression and role of ITGB4 in glioma. We finally analyzed the possible mechanism by immune infiltration and single-cell sequencing analysis. Here, we found that ITGB4 is upregulated in glioma and accurately predicts the prognosis of lower grade glioma (LGG). Univariate and multivariate Cox regression analyses showed that ITGB4 is a risk factor for LGG. Immunohistochemical analysis confirmed that ITGB4 accurately predicts LGG prognosis. Non-negative matrix factorization (NMF) cluster analysis showed that ITGB4 was closely related to immune related genes. Immune cell infiltration and single cell sequencing analyses indicated that ITGB4 may be closely related to the microenvironment of gliomas, especially tumor-associated fibroblasts. ITGB4 is a promising diagnostic and therapeutic factor in LGG patients.

Unraveling dedifferentiation and metastasis traces in pancreatic ductal adenocarcinoma ductal cells: Insights from single-cell RNA sequencing analysis of ITGB4 and C19orf33.

Pancreatic Ductal Adenocarcinoma (PDAC) ranks among the most prevalent gastrointestinal malignancies, with risk factors including smoking, alcohol abuse, diabetes mellitus, obesity, age, family history, and genetic predisposition. Extensive research has focused on unraveling biomarkers and molecular intricacies associated with PDAC. Leveraging data from the Gene Expression Omnibus microarray and single-cell RNA sequencing datasets, our study identified ITGB4 and C19orf33 as potentially differentially expressed genes in PDAC samples when contrasted with non-malignant tissues. Notably, these genes exhibited a strong correlative expression pattern, primarily within ductal cells. Gene Expression Profiling Interactive Analysis corroborated our findings, further confirming the correlation between ITGB4 and C19orf33. Additionally, we conducted experiments involving two pivotal PDAC-related cell lines, MIA PaCa-2 and PANC-1, treated with oxaliplatin and 5-Fluorouracil. We also assessed the expression of these candidate genes in PDAC samples in comparison to adjacent normal tissues. Our findings revealed that C19orf33 is upregulated in PDAC samples, and treatment of PDAC cells with chemotherapeutic agents led to a correlated decrease in the expression of both ITGB4 and C19orf33. These co-expressed and correlated genes are implicated in relevant signaling pathways, suggesting shared biological activities that may contribute to the promotion of metastasis within malignant ductal cells. This study identifies ITGB4 and C19orf33 as key genes potentially shedding light on the molecular mechanisms driving tumorigenesis and metastasis in PDAC. These genes hold promise as potential diagnostic and therapeutic targets, offering valuable insights into the management of this challenging disease.

Identification of ITGB4 as a novel tumor promoting gene in lung adenocarcinoma (LUAD).

As the most frequently diagnosed cancer, lung cancer (LC) is the most common cause of cancer­related death worldwide. In total, ~85% of malignant lung tumors belong to non­small cell LC, of which ~50% are lung adenocarcinoma (LUAD). Integrin subunit ß4 (ITGB4) is upregulated in lung glandular cancer and elevated ITGB4 levels predict an adverse clinical outcome. However, the biological function of ITGB4 in promoting LUAD progression remains unclear. In the present study, the upregulation of ITGB4 in LUAD tissue samples was demonstrated. To understand the biological role of ITGB4, ITGB4 expression was knocked down in A549 and PC9 cells through transfection with specific small interfering RNAs. The results demonstrated that the downregulation of ITGB4 attenuated A549 and PC9 cell proliferation, promoted cell apoptosis and inhibited colony formation, cell migration and cell invasion. To understand the mechanism of ITGB4, high throughput sequencing was performed using ITGB4­knocked down A549 cells, followed by bioinformatics analysis. It was found that the genes upregulated by ITGB4 were significantly enriched in metabolism and related pathways, and the genes downregulated by ITGB4 were enriched in cell cycle and related pathways. In conclusion, the findings of the present study highlighted the oncogenic function of ITGB4 in LUAD and uncovered potential mechanisms fundamental to the progression of the disease.

Integrin α6ß4 Confers Doxorubicin Resistance in Cancer Cells by Suppressing Caspase-3-Mediated Apoptosis: Involvement of N-Glycans on ß4 Integrin Subunit.

Drug resistance is a major obstacle to successful cancer treatment. Therefore, it is essential to understand the molecular mechanisms underlying drug resistance to develop successful therapeutic strategies. α6ß4 integrin confers resistance to apoptosis and regulates the survival of cancer cells; however, it remains unclear whether α6ß4 integrin is directly involved in chemoresistance. Here, we show that α6ß4 integrin promotes doxorubicin resistance by decreasing caspase-3-mediated apoptosis. We found that the overexpression of α6ß4 integrin by the ß4 integrin gene rendered MDA-MB435S and Panc-1 cells more resistant to doxorubicin than control cells. The acquired resistance to doxorubicin by α6ß4 integrin expression was abolished by the deletion of the cytoplasmic signal domain in ß4 integrin. Similar results were found in MDA-MB435S and Panc-1 cells when N-glycan-defective ß4 integrin mutants were overexpressed or bisecting GlcNAc residues were increased on ß4 integrin by the co-expression of N-acetylglucosaminyltransferase III with ß4 integrin. The abrogation of α6ß4 integrin-mediated resistance to doxorubicin was accompanied by reduced cell viability and an increased caspase-3 activation. Taken together, our results clearly suggest that α6ß4 integrin signaling plays a key role in the doxorubicin resistance of cancer cells, and N-glycans on ß4 integrin are involved in the regulation of cancer cells.

Integrin ß4 promotes DNA damage-related drug resistance in triple-negative breast cancer via TNFAIP2/IQGAP1/RAC1.

Anti-tumor drug resistance is a challenge for human triple-negative breast cancer (TNBC) treatment. Our previous work demonstrated that TNFAIP2 activates RAC1 to promote TNBC cell proliferation and migration. However, the mechanism by which TNFAIP2 activates RAC1 is unknown. In this study, we found that TNFAIP2 interacts with IQGAP1 and Integrin ß4. Integrin ß4 activates RAC1 through TNFAIP2 and IQGAP1 and confers DNA damage-related drug resistance in TNBC. These results indicate that the Integrin ß4/TNFAIP2/IQGAP1/RAC1 axis provides potential therapeutic targets to overcome DNA damage-related drug resistance in TNBC.

Integrin ß4 induced epithelial-to-mesenchymal transition involves miR-383 mediated regulation of GATA6 levels.

BACKGROUND: The process of transdifferentiating epithelial cells to mesenchymal-like cells (EMT) involves cells gradually taking on an invasive and migratory phenotype. Many cell adhesion molecules are crucial for the management of EMT, integrin ß4 (ITGB4) being one among them. Although signaling downstream of ITGB4 has been reported to cause changes in the expression of several miRNAs, little is known about the role of such miRNAs in the process of EMT. METHODS AND RESULTS: The cytoplasmic domain of ITGB4 (ITGB4CD) was ectopically expressed in HeLa cells to induce ITGB4 signaling, and expression analysis of mesenchymal markers indicated the induction of EMT. ß-catenin and AKT signaling pathways were found to be activated downstream of ITGB4 signaling, as evidenced by the TOPFlash assay and the levels of phosphorylated AKT, respectively. Based on in silico and qRT-PCR analysis, miR-383 was selected for functional validation studies. miR-383 and Sponge were ectopically expressed in HeLa, thereafter, western blot and qRT-PCR analysis revealed that miR-383 regulates GATA binding protein 6 (GATA6) post-transcriptionally. The ectopic expression of shRNA targeting GATA6 caused the reversal of EMT and ß catenin activation downstream of ITGB4 signaling. Cell migration assays revealed significantly high cell migration upon ectopic expression ITGB4CD, which was reversed upon ectopic co-expression of miR-383 or GATA6 shRNA. Besides, ITGB4CD promoted EMT in in ovo xenograft model, which was reversed by ectopic expression of miR-383 or GATA6 shRNA. CONCLUSION: The induction of EMT downstream of ITGB4 involves a signaling axis encompassing AKT/miR-383/GATA6/ß-catenin.

Conditional knockout of ITGB4 in bronchial epithelial cells directs bronchopulmonary dysplasia.

Neonatal respiratory system disease is closely associated with embryonic lung development. Our group found that integrin ß4 (ITGB4) is downregulated in the airway epithelium of asthma patients. Asthma is the most common chronic respiratory illness in childhood. Therefore, we suspect whether the deletion of ITGB4 would affect fetal lung development. In this study, we characterized the role of ITGB4 deficiency in bronchopulmonary dysplasia (BPD). ITGB4 was conditionally knocked out in CCSP-rtTA, Tet-O-Cre and ITGB4f/f triple transgenic mice. Lung tissues at different developmental stages were collected for experimental detection and transcriptome sequencing. The effects of ITGB4 deficiency on lung branching morphogenesis were observed by fetal mouse lung explant culture. Deleting ITGB4 from the airway epithelial cells results in enlargement of alveolar airspaces, inhibition of branching, the abnormal structure of epithelium cells and the impairment of cilia growth during lung development. Scanning electron microscopy showed that the airway epithelial cilia of the ß4ccsp.cre group appear to be sparse, shortened and lodging. Lung-development-relevant factors such as SftpC and SOX2 significantly decreased both mRNA and protein levels. KEGG pathway analysis indicated that multiple ontogenesis-regulating-relevant pathways converge to FAK. Accordingly, ITGB4 deletion decreased phospho-FAK, phospho-GSK3ß and SOX2 levels, and the correspondingly contrary consequence was detected after treatment with GSK3ß agonist (wortmannin). Airway branching defect of ß4ccsp.cre mice lung explants was also partly recovered after wortmannin treatment. Airway epithelial-specific deletion of ITGB4 contributes to lung developmental defect, which could be achieved through the FAK/GSK3ß/SOX2 signal pathway.

A comprehensive investigation regarding the clinical significance of ITGB4 in oral squamous cell carcinoma combining immunohistochemistry, RNA-seq, and microarray data.

OBJECTIVE: Integrin subunit beta 4 (ITGB4), a receptor for laminins, was an oncoprotein in several malignancies. However, its clinical role in oral squamous cell carcinoma (OSCC) remains unclear. MATERIALS AND METHODS: Firstly, 99 OSCC and 13 normal oral epithelium samples were employed for immunohistochemistry (IHC) for detecting the expression level of ITGB4 protein in OSCC. Subsequently, 971 OSCC and 281 non-cancerous specimens from RNA-seq and 18 microarrays were applied for investigating the expression of ITGB4 mRNA. Furthermore, to explore the potential mechanism of ITGB4 in OSCC, the co-expressed genes of ITGB4 were initially screened using all available datasets, and were further utilized for the gene enrichment analysis. RESULTS: First, IHC showed a distinctively higher expression level of the ITGB4 protein in the OSCC group than that in the normal controls. Second, expression profile from RNA-seq and microarrays reflected that ITGB4 mRNA was dramatically overexpressed in OSCC tissues compared with non-tumor tissues. Third, standardized mean difference (SMD) with the area under the summary receiver operating characteristic (sROC) curve combining all incorporated data revealed that ITGB4 was consistently significantly upregulated in OSCC tissues, with the SMD value being 1.31 and the area under the sROC curve being 0.82. Lastly, 184 upregulated and 179 downregulated co-expressed genes of ITGB4 were utilized for enrichment analysis, which demonstrated that ITGB4 might influence the pathogenesis of OSCC through cell cycle, ECM-receptor interaction and focal adhesion pathways. CONCLUSIONS: ITGB4 might play a pivotal role in the tumorigenesis and progression of OSCC, making it a promising biomarker of OSCC.

A heterozygous mutation in ITGB4 causing a mild phenotype of junctional epidermolysis bullosa.

Mutations in ITGB4 are known to cause autosomal recessive junctional epidermolysis bullosa (JEB), which is manifested by severe blistering and granulation tissue, usually complicating pyloric atresia and even leading to death. ITGB4-associated autosomal dominant epidermolysis bullosa has rarely been documented. Herein, we identified a heterozygous pathogenic variant (c.433G>T; p.Asp145Tyr) in ITGB4 causing a mild phenotype of JEB in a Chinese family.

TCN1 Deficiency Inhibits the Malignancy of Colorectal Cancer Cells by Regulating the ITGB4 Pathway.

Background/Aims: This study aimed to investigate the biological function and regulatory mechanism of TCN1 in colorectal cancer (CRC). Methods: We studied the biological function of TCN1 by performing gain-of-function and loss-of-function analyses in HCT116 cell lines; examined the effects of TCN1 on the proliferation, apoptosis, and invasion of CRC cells; and determined potential molecular mechanisms using HCT116 and SW480 CRC lines and mouse xenotransplantation models. Tumor xenograft and colonization assays were performed to detect the tumorigenicity and metastatic foci of cells in vivo. Results: TCN1 knockdown attenuated CRC cell proliferation and invasion and promoted cell apoptosis. Overexpression of TCN1 yielded the opposite effects. In addition, TCN1-knockdown HCT116 cells failed to form metastatic foci in the peritoneum after intravenous injection. Molecular mechanism analyses showed that TCN1 interacted with integrin subunit ß4 (ITGB4) to positively regulate the expression of ITGB4. TCN1 knockdown promoted the degradation of ITGB4 and increased the instability of ITGB4 and filamin A. Downregulation of ITGB4 at the protein level resulted in the disassociation of the ITGB4/plectin complex, leading to cytoskeletal damage. Conclusions: TCN1 might play an oncogenic role in CRC by regulating the ITGB4 signaling pathway.

Airway epithelial ITGB4 deficiency induces airway remodeling in a mouse model.

BACKGROUND: Airway epithelial cells (AECs) with impaired barrier function contribute to airway remodeling through the activation of epithelial-mesenchymal trophic units (EMTUs). Although the decreased expression of ITGB4 in AECs is implicated in the pathogenesis of asthma, how ITGB4 deficiency impacts airway remodeling remains obscure. OBJECTIVE: This study aims to determine the effect of epithelial ITGB4 deficiency on the barrier function of AECs, asthma susceptibility, airway remodeling, and EMTU activation. METHODS: AEC-specific ITGB4 conditional knockout mice (ITGB4-/-) were generated and an asthma model was employed by the sensitization and challenge of house dust mite (HDM). EMTU activation-related growth factors were examined in ITGB4-silenced primary human bronchial epithelial cells of healthy subjects after HDM stimulation. Dexamethasone, the inhibitors of JNK phosphorylation or FGF2 were administered for the identification of the molecular mechanisms of airway remodeling in HDM-exposed ITGB4-/- mice. RESULTS: ITGB4 deficiency in AECs enhanced asthma susceptibility and airway remodeling by disrupting airway epithelial barrier function. Aggravated airway remodeling in HDM-exposed ITGB4-/- mice was induced through the enhanced activation of EMTU mediated by Src homology domain 2-containing protein tyrosine phosphatase 2/c-Jun N-terminal kinase/Jun N-terminal kinase-dependent transcription factor/FGF2 (SHP2/JNK/c-Jun/FGF2) signaling pathway, which was partially independent of airway inflammation. Both JNK and FGF2 inhibitors significantly inhibited the aggravated airway remodeling and EMTU activation in HDM-exposed ITGB4-/- mice. CONCLUSIONS: Airway epithelial ITGB4 deficiency induces airway remodeling in a mouse model of asthma through enhanced EMTU activation that is regulated by the SHP2/JNK/c-Jun/FGF2 pathway.

KCNF1 promotes lung cancer by modulating ITGB4 expression.

Lung cancer continues to be the leading cause of cancer death in the United States. Despite recent advances, the five-year survival rate for lung cancer compared to other cancers still remains fairly low. The discovery of molecular targets for lung cancer is key to the development of new approaches and therapies. Electrically silent voltage-gated potassium channel (KvS) subfamilies, which are unable to form functional homotetramers, are implicated in cell-cycle progression, cell proliferation and tumorigenesis. Here, we analyzed the expression of KvS subfamilies in human lung tumors and identified that potassium voltage-gated channel subfamily F member 1 (KCNF1) was up-regulated in non-small cell lung cancer (NSCLC). Silencing of KCNF1 in NSCLC cell lines reduced cell proliferation and tumor progression in mouse xenografts, re-established the integrity of the basement membrane, and enhanced cisplatin sensitivity. KCNF1 was predominately localized in the nucleoplasm and likely mediated its functions in an ion-independent manner. We identified integrin ß4 subunit (ITGB4) as a downstream target for KCNF1. Our findings suggest that KCNF1 promotes lung cancer by enhancing ITGB4 signaling and implicate KCNF1 as a novel therapeutic target for lung cancer.

Shear-Induced ITGB4 Promotes Endothelial Cell Inflammation and Atherosclerosis.

The local heterogeneity in the distribution of atherosclerotic lesions is caused by local flow patterns. The integrin family plays crucial regulatory roles in diverse biological processes, but knowledge of integrin ß4 (ITGB4) in shear stress-induced atherosclerosis is limited. This study clarified that low shear stress (LSS) regulates the generation of ITGB4 in endothelial cells with atheroprone phenotype to identify ITGB4's role in atherosclerosis. We found that LSS led to an increase in ITGB4 protein expression both in vitro and in vivo. ITGB4 knockdown attenuated inflammation and ROS generation in human umbilical vein endothelial cells (HUVECs) and reduced atherosclerotic lesion areas in ApoE-/- mice fed with HFD, largely independent of effects on the lipid profile. Mechanistically, ITGB4 knockdown altered the phosphorylation levels of SRC, FAK, and NFκB in HUVECs under LSS conditions. In addition, the knockdown of NFκB inhibited the production of ITGB4 and SRC phosphorylation, and the knockdown of SRC downregulated ITGB4 protein expression and NFκB activation. These data demonstrate a critical role of ITGB4 in atherosclerosis via modulation of endothelial cell inflammation, and ITGB4/SRC/NFκB might form a positive feedback loop in the regulation of endothelial cell inflammation.

Autosomal recessive inheritance of a novel missense mutation of ITGB4 for Epidermolysis-Bullosa pyloric-atresia: a case report.

Epidermolysis-Bullosa (EB), a rare Mendelian disorder, exhibits complex phenotypic and locus-heterogeneity. We identified a nuclear family of clinically unaffected parents with two offsprings manifesting EB-Pyloric-Atresia (EB-PA), with a variable clinical severity. We generated whole exome sequence data on all four individuals to (1) identify the causal mutation behind EB-PA (2) understand the background genetic variation for phenotype variability of the siblings. We assumed an autosomal recessive mode of inheritance and used suites of bioinformatic and computational tools to collate information through global databases to identify the causal genetic variant for the disease. We also investigated variations in key genes that are likely to impact phenotype severity. We identified a novel missense mutation in the ITGB4 gene (p.Ala1227Asp), for which the parents were heterozygous and the children homozygous. The mutation in ITGB4 gene, predicted to reduce the stability of the primary alpha6beta4-plectin complex compared to all previously studied mutations on ITGB4 reported to cause EB.

ITGB4 Deficiency in Airway Epithelium Aggravates RSV Infection and Increases HDM Sensitivity.

Background: The heterogeneity of RSV-infected pathology phenotype in early life is strongly associate with increased susceptibility of asthma in later life. However, the inner mechanism of this heterogeneity is still obscure. ITGB4 is a down-regulated adhesion molecular in the airway epithelia of asthma patients which may participate in the regulation of RSV infection related intracellular pathways. Object: This study was designed to observe the involvement of ITGB4 in the process of RSV infection and the effect of ITGB4 deficiency on anti-RSV responses of airway epithelia. Results: RSV infection caused a transient decrease of ITGB4 expression both in vitro and in vivo. Besides, ITGB4 deficiency induced not only exacerbated RSV infection, but also enhanced HDM sensitivity in later life. Moreover, IFN III (IFN-λ) was significantly suppressed during RSV infection in ITGB4 deficient airway epithelial cells. Furthermore, the suppression of IFN-λ were regulated by IRF-1 through the phosphorylation of EGFR in airway epithelial cells after RSV infection. Conclusion: These results demonstrated the involvement of ITGB4 deficiency in the development of enhance RSV infection in early life and the increased HDM sensitivity in later life by down-regulation of IFN-λ through EGFR/IRF-1 pathway in airway epithelial cells.

MicroRNA-485-5p targets keratin 17 to regulate oral cancer stemness and chemoresistance via the integrin/FAK/Src/ERK/ß-catenin pathway.

BACKGROUND: The development of drug resistance in oral squamous cell carcinoma (OSCC) that frequently leads to recurrence and metastasis after initial treatment remains an unresolved challenge. Presence of cancer stem cells (CSCs) has been increasingly reported to be a critical contributing factor in drug resistance, tumor recurrence and metastasis. Thus, unveiling of mechanisms regulating CSCs and potential targets for developing their inhibitors will be instrumental for improving OSCC therapy. METHODS: siRNA, shRNA and miRNA that specifically target keratin 17 (KRT17) were used for modulation of gene expression and functional analyses. Sphere-formation and invasion/migration assays were utilized to assess cancer cell stemness and epithelial mesenchymal transition (EMT) properties, respectively. Duolink proximity ligation assay (PLA) was used to examine molecular proximity between KRT17 and plectin, which is a large protein that binds cytoskeleton components. Cell proliferation assay was employed to evaluate growth rates and viability of oral cancer cells treated with cisplatin, carboplatin or dasatinib. Xenograft mouse tumor model was used to evaluate the effect of KRT17- knockdown in OSCC cells on tumor growth and drug sensitization. RESULTS: Significantly elevated expression of KRT17 in highly invasive OSCC cell lines and advanced tumor specimens were observed and high KRT17 expression was correlated with poor overall survival. KRT17 gene silencing in OSCC cells attenuated their stemness properties including markedly reduced sphere forming ability and expression of stemness and EMT markers. We identified a novel signaling cascade orchestrated by KRT17 where its association with plectin resulted in activation of integrin ß4/α6, increased phosphorylation of FAK, Src and ERK, as well as stabilization and nuclear translocation of ß-catenin. The activation of this signaling cascade was correlated with enhanced OSCC cancer stemness and elevated expression of CD44 and epidermal growth factor receptor (EGFR). We identified and demonstrated KRT17 to be a direct target of miRNA-485-5p. Ectopic expression of miRNA-485-5p inhibited OSCC sphere formation and caused sensitization of cancer cells towards cisplatin and carboplatin, which could be significantly rescued by KRT17 overexpression. Dasatinib treatment that inhibited KRT17-mediated Src activation also resulted in OSCC drug sensitization. In OSCC xenograft mouse model, KRT17 knockdown significantly inhibited tumor growth, and combinatorial treatment with cisplatin elicited a greater tumor inhibitory effect. Consistently, markedly reduced levels of integrin ß4, active ß-catenin, CD44 and EGFR were observed in the tumors induced by KRT17 knockdown OSCC cells. CONCLUSIONS: A novel miRNA-485-5p/KRT17/integrin/FAK/Src/ERK/ß-catenin signaling pathway is unveiled to modulate OSCC cancer stemness and drug resistance to the common first-line chemotherapeutics. This provides a potential new therapeutic strategy to inhibit OSCC stem cells and counter chemoresistance.