NEDD4L mediates ITGB4 ubiquitination and degradation to suppress esophageal carcinoma progression.

The ubiquitination-mediated protein degradation exerts a vital role in the progression of multiple tumors. NEDD4L, which belongs to the E3 ubiquitin ligase NEDD4 family, is related to tumor genesis, metastasis and drug resistance. However, the anti-tumor role of NEDD4L in esophageal carcinoma, and the potential specific recognition substrate remain unclear. Based on public esophageal carcinoma database and clinical sample data, it was discovered in this study that the expression of NEDD4L in esophageal carcinoma was apparently lower than that in atypical hyperplastic esophageal tissue and esophageal squamous epithelium. Besides, patients with high expression of NEDD4L in esophageal carcinoma tissue had longer progression-free survival than those with low expression. Experiments in vivo and in vitro also verified that NEDD4L suppressed the growth and metastasis of esophageal carcinoma. Based on co-immunoprecipitation and proteome analysis, the NEDD4L ubiquitination-degraded protein ITGB4 was obtained. In terms of the mechanism, the HECT domain of NEDD4L specifically bound to the Galx-ß domain of ITGB4, which modified the K915 site of ITGB4 in an ubiquitination manner, and promoted the ubiquitination degradation of ITGB4, thus suppressing the malignant phenotype of esophageal carcinoma.

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.

YAP/TAZ-mediated regulation of laminin 332 is enabled by ß4 integrin repression of ZEB1 to promote ferroptosis resistance.

We are interested in the contribution of integrins and the extracellular matrix to epithelial differentiation in carcinomas. This study was motivated by our finding that the Hippo effectors YAP and TAZ can sustain the expression of laminin 332 (LM332), the predominant ECM ligand for the integrin ß4, in breast carcinoma cells with epithelial differentiation. More specifically, we observed that YAP and TAZ regulate the transcription of the LAMC2 subunit of LM332. Given that the ß4-LM332 axis is associated with epithelial differentiation and YAP/TAZ have been implicated in carcinoma de-differentiation, we sought to resolve this paradox. Here, we observed that the ß4 integrin sustains the expression of miR-200s that target the transcription factor ZEB1 and that ZEB1 has a pivotal role in determining the nature of YAP/TAZ-mediated transcription. In the presence of ß4, ZEB1 expression is repressed enabling YAP/TAZ/TEAD-mediated transcription of LAMC2. The absence of ß4, however, induces ZEB1, and ZEB1 binds to the LAMC2 promoter to inhibit LAMC2 transcription. YAP/TAZ-mediated regulation of LAMC2 has important functional consequences because we provide evidence that LM332 enables carcinoma cells to resist ferroptosis in concert with the ß4 integrin.

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.

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.

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.

Exosome-transmitted FOSL1 from cancer-associated fibroblasts drives colorectal cancer stemness and chemo-resistance through transcriptionally activating ITGB4.

Cancer-associated fibroblasts (CAFs) have been proved to facilitate colorectal cancer (CRC) development, either with boosting chemo-resistance by communicating with CRC cells in the tumor microenvironment. However, the underlying molecular mechanisms remain largely unclear. Relative expressions of FOSL1 and ITGB4, either with their correlations in CRC tissues, were assessed using qRT-PCR analysis. Also, Kaplan-Meier survival analysis was employed for evaluating the prognosis. Identification of CAFs was determined by the detection of specific makers (α-SMA, FAP, and FSP1) using western blot and immunofluorescence staining. Cell proliferation, self-renewal capacity, and cell apoptosis were estimated by CCK-8, sphere-formation, and flow cytometry assays. Transcriptional regulation of FOSL1 on integrin ß4 (ITGB4) was confirmed using ChIP and dual-luciferase reporter assays. Increased FOSL1 and ITGB4 in CRC tissues were both positively correlated with the poor prognosis of CRC patients. Interestingly, FOSL1 was enriched in the CAFs isolated from CRC stroma, instead of ITGB4. CRC cells under a co-culture system with CAFs-conditioned medium (CAFs-CM) exhibited increased FOSL1, promotive cell proliferation, and reduced apoptosis, while these effects could be blocked by exosome inhibitor (GW4869). Moreover, CAFs-derived exosomal FOSL1 was validated to enhance proliferative ability and oxaliplatin resistance of CRC cells. Our results uncovered that CAFs-derived exosomes could transfer FOSL1 to CRC cells, thereby promoting CRC cell proliferation, stemness, and oxaliplatin resistance by transcriptionally activating ITGB4.

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.

Cerebral arterioles express the laminin subunits α4 and α5 in conjunction with α6ß4 integrin, but strongly downregulate laminin α4 during hypoxia-induced arteriogenic remodeling.

Previous studies have shown that expression of the endothelial laminin receptor α6ß4 integrin in the brain is uniquely restricted to arterioles. As exposure to chronic mild hypoxia (CMH, 8 % O2) stimulates robust angiogenic and arteriogenic remodeling responses in the brain, the goal of this study was to determine how CMH influences cerebrovascular expression of the ß4 integrin as well as its potential ligands, laminin 411 and 511, containing the α4 and α5 laminin subunits respectively, and then define how aging impacts this expression. We observed the following: (i) CMH launched a robust arteriogenic remodeling response both in the young (10 weeks) and aged (20 months) brain, correlating with an increased number of ß4 integrin+ vessels, (ii) while the laminin α4 subunit is expressed evenly across all cerebral blood vessels, laminin α5 was highly expressed preferentially on ß4 integrin+ arterioles, (iii) CMH-induced arteriolar remodeling was associated with strong downregulation of the laminin α4 subunit but no change in the laminin α5 subunit, (iv) in addition to its expression on arterioles, ß4 integrin was also expressed at lower levels on capillaries specifically in white matter (WM) tracts but not in the grey matter (GM), and (v), these observations were consistent in both the brain and spinal cord, and age had no obvious impact. Taken together, our findings suggest that laminin 511 may be a specific ligand for α6ß4 integrin and that dynamic switching of the laminin subunits α4 and α5 might play an instructive role in arteriogenic remodeling. Furthermore, ß4 integrin expression differentiates WM from GM capillaries, highlighting a novel and important difference.

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.

METTL14-mediated N6-methyladenosine modification of Col17a1/Itgα6/Itgß4 governs epidermal homeostasis.

BACKGROUND: N6-methyladenosine (m6A) is the most abundant and reversible modification occurring in eukaryotic mRNAs, however, its functions in mammalian epidermal development are still not fully elucidated. OBJECTIVE: To explore the role of METTL14 (Methyltransferase like 14), one of the m6A methyltransferases, in maintaining epidermal homeostasis. METHODS: We constructed mice with Mettl14-inactivation in the epidermal basal cells. The phenotype was explored by H&E staining and immunofluorescence staining. To explore the underlying mechanisms, we performed RNA-seq, Ribosome profiling and MeRIP-seq on wild-type and Mettl14-inactivation epidermal keratinocytes. Moreover, HaCaT cells were used for in vitro validation. RESULTS: Inactivation of Mettl14 in murine epidermis led to transient thicker epidermis and exhaustion of the epidermal stem cell pool. Interestingly, we found that the mRNA of type XVII collagen (Col17a1), integrin ß4 (Itgß4) and α6 (Itgα6) had m6A modifications, and the proteins expression were decreased in Mettl14-inactivated epidermis. Furthermore, in epidermis-specific Mettl4-inactivated mice, the epidermis was detached from the dermis and presented a phenotype similar to junctional epidermolysis bullosa (JEB), which may result from hemidesmosomes damage (decrease of COL17A1, ITGB4 and ITGA6). Knockdown of Mettl14 in HaCaT cells impaired the self-renewal and decreased the protein level of COL17A1, ITGB4 and ITGA6 and Itgß4 knockdown inhibited colony formation. CONCLUSION: Our study highlighted the role of METTL14 in the maintenance of epidermal homeostasis and identified its critical role through m6A-mediated translational inhibition of Col17a1, Itgß4 and Itgα6. Our study suggested that METTL14 may be a potential therapeutic target for the treatment of hemidesmosomes-deficient diseases, such as JEB.

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.

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.

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.

Biological and clinical significance of the YKL-40/osteopontin-integrin ß4-p70S6K axis induced by macrophages in early oesophageal squamous cell carcinoma.

M2 macrophages contribute to the progression of oesophageal squamous cell carcinoma (ESCC); however, the roles of M2 macrophages in early ESCC remain unclear. To clarify the biological mechanisms underlying the interaction between M2 macrophages and oesophageal epithelial cells in early-stage ESCC, in vitro co-culture assays between the immortalised oesophageal epithelial cell line Het-1A and cytokine-defined M2 macrophages were established. Co-culture with M2 macrophages promoted the proliferation and migration of Het-1A cells via the mTOR-p70S6K signalling pathway activated by YKL-40, also known as chitinase 3-like 1, and osteopontin (OPN) that were hypersecreted in the co-culture supernatants. YKL-40 and OPN promoted the above phenotypes of Het-1A by making a complex with integrin ß4 (ß4). Furthermore, YKL-40 and OPN promoted M2 polarisation, proliferation, and migration of macrophages. To validate the pathological and clinical significances of in vitro experimental results, immunohistochemistry of human early ESCC tissues obtained by endoscopic submucosal dissection (ESD) was performed, confirming the activation of the YKL-40/OPN-ß4-p70S6K axis in the tumour area. Moreover, epithelial expression of ß4 and the number of epithelial and stromal infiltrating YKL-40- and OPN-positive cells correlated with the Lugol-voiding lesions (LVLs), a well-known predictor of the incidence of metachronous ESCC. Furthermore, the combination of high expression of ß4 and LVLs or high numbers of epithelial and stromal infiltrating YKL-40- and OPN-positive immune cells could more clearly detect the incidence of metachronous ESCC than each of the parameters alone. Our results demonstrated that the YKL-40/OPN-ß4-p70S6K axis played important roles in early-stage ESCC, and the high expression levels of ß4 and high numbers of infiltrating YKL-40- and OPN-positive immune cells could be useful predictive parameters for the incidence of metachronous ESCC after ESD. © 2023 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

EIF4a3-regulated circRABL2B regulates cell stemness and drug sensitivity of lung cancer via YBX1-dependent downregulation of MUC5AC expression.

Identification of mucin modulators is of remarkable significance to facilitate mucin-based antineoplastic therapy. However, little is known about circular RNAs (circRNAs) on regulating mucins. Dysregulated mucins and circRNAs were identified via high-throughput sequencing and their relationships with lung cancer survival were analyzed in tumor samples of 141 patients. The biological functions of circRABL2B were determined via gain- and loss-of-function experiments and exosome-packaged circRABL2B treatment in cells, patient-derived lung cancer organoids and nude mice. We identified that circRABL2B was negatively correlated with MUC5AC. Patients with low circRABL2B and high MUC5AC displayed the poorest survival (HR=2.00; 95% CI=1.12-3.57). Overexpressed circRABL2B significantly inhibited cell malignant phenotypes, while it knock-down exerted opposite effects. CircRABL2B interacted with YBX1 to inhibit MUC5AC, and subsequently suppressed integrin ß4/pSrc/p53 signaling and impoverished cell stemness, and promoted erlotinib sensitivity. Exosome-packaged circRABL2B exerted significant anti-cancer actions in cells, patient-derived lung cancer organoids and nude mice. Meanwhile, circRABL2B in plasma exosomes could distinguish early-stage lung cancer patients from healthy controls. Finally, we found circRABL2B was downregulated at the transcriptional level, and EIF4a3 involved the formation of circRABL2B. In conclusion, our data suggest that circRABL2B counteracts lung cancer progression via MUC5AC/integrin ß4/pSrc/p53 axis, which provides a rationale to enhance the efficacy of anti-MUCs treatment in lung cancer.

Identification of a Favorable Prognostic Subgroup in Oral Squamous Cell Carcinoma: Characterization of ITGB4/PD-L1high with CD8/PD-1high.

Integrin ß4 (ITGB4) is a member of the integrin family, which plays a crucial role in mediating cell adhesion to the extracellular matrix. Recent studies have demonstrated that ITGB4 is involved in tumorigenesis and metastasis during the development of cancer. However, the role of ITGB4 in oral squamous cell carcinoma (OSCC) remains unclear. A Multiplex immunohistochemistry (OPAL™, mIHC) assay was employed to stain ITGB4, ALDH1, PD-L1, cytokeratin (CK), CD8 and PD-1 in a human OSCC tissue microarray, containing 26 normal oral epithelium samples, 21 oral epithelium dysplasia samples and 76 OSCC samples. The expression pattern and clinicopathological characteristics of ITGB4 were analyzed and compared with those of PD-1, PD-L1, ALDH1 and CD8. The correlation between subgroups of tumor cells, including ITGB4+PD-L1+ and ITGB4+ALDH1+, and subgroups of T cells, including CD8+ and CD8+PD-1+, was evaluated using two-tailed Pearson's statistics. A Kaplan-Meier curve was built, and a log-rank test was performed to analyze the survival rate of different subgroups. The mIHC staining results show that ITGB4 was mostly expressed in the tumor cells, with a significant increase in the OSCC specimens compared with normal oral epithelium and oral epithelium dysplasia. The paired analysis, conducted between the OSCC tumor tissue and normal paracancer mucosa, confirmed the results. The study further revealed that ITGB4+PD-L1+ cancer cells, but not ITGB4+ALDH1+ cancer cells, were significantly associated with the infiltration of CD8+ T cells (positivity p = 0.005, positive number p = 0.03). Additionally, ITGB4+PD-L1+ tumor cells were positively correlated with CD8+PD-1+ T cells (positivity p = 0.02, positive number p = 0.03). Most intriguingly, the subgroup of ITGB4/PD-L1high with CD8/PD-1high displayed the best prognosis compared with the other considered subgroups. The results show that the expression of ITGB4 was increased in OSCC compared with normal oral mucosa. Furthermore, a specific subgroup with high levels of expression of ITGB4/PD-L1 and CD8/PD-1 was found to have a relatively better prognosis compared with the other subgroups. Ultimately, this study sheds light on the potential role of ITGB4 in OSCC and provides a basis for further investigation.

TMTC1 promotes invasiveness of ovarian cancer cells through integrins ß1 and ß4.

Ovarian cancer is the most lethal gynecological malignancy and is characterized by peritoneal disseminated metastasis. Although O-mannosyltransferase TMTC1 is highly expressed by ovarian cancer, its pathophysiological role in ovarian cancer remains unclear. Here, immunohistochemistry showed that TMTC1 was overexpressed in ovarian cancer tissues compared with adjacent normal ovarian tissues, and high TMTC1 expression was associated with poor prognosis in patients with ovarian cancer. Silencing TMTC1 reduced ovarian cancer cell viability, migration, and invasion in vitro, as well as suppressed peritoneal tumor growth and metastasis in vivo. Moreover, TMTC1 knockdown reduced cell-laminin adhesion, which was associated with the decreased phosphorylation of FAK at pY397. Conversely, TMTC1 overexpression promoted these malignant properties in ovarian cancer cells. Glycoproteomic analysis and Concanavalin A (ConA) pull-down assays showed that integrins ß1 and ß4 were novel O-mannosylated protein substrates of TMTC1. Furthermore, TMTC1-mediated cell migration and invasion were significantly reversed by siRNA-mediated knockdown of integrin ß1 or ß4. Collectively, these results suggest that TMTC1-mediated invasive behaviors are primarily through integrins ß1 and ß4 and that TMTC1 is a potential therapeutic target for ovarian cancer.

Inhibition of the SLC35B2-TPST2 Axis of Tyrosine Sulfation Attenuates the Growth and Metastasis of Pancreatic Ductal Adenocarcinom.

BACKGROUND & AIMS: Pancreatic ductal adenocarcinoma (PDAC) is the fourth leading cause of cancer deaths in the United States. Tyrosine sulfation, catalyzed by the tyrosylprotein sulfotransferase 2 (TPST2), is a post-translational modification essential for protein-protein interactions and cellular functions. Solute carrier family 35 member B (SLC35B2) is a key transporter that transports the universal sulfate donor 3'-phosphoadenosine 5'-phosphosulfate into the Golgi apparatus where the protein sulfation occurs. The goal of this study was to determine whether and how the SLC35B2-TPST2 axis of tyrosine sulfation plays a role in PDAC. METHODS: Gene expression was analyzed in PDAC patients and mice. Human PDAC MIA PaCa-2 and PANC-1 cells were used for in vitro studies. TPST2-deficient MIA PaCa-2 cells were generated to assess xenograft tumor growth in vivo. Mouse PDAC cells derived from the KrasLSL-G12D/+;Tp53L/+;Pdx1-Cre (KPC) mice were used to generate Tpst2 knockout KPC cells to evaluate tumor growth and metastasis in vivo. RESULTS: High expressions of SLC35B2 and TPST2 were correlated with poor PDAC patient survival. Knocking down SLC35B2 or TPST2, or pharmacologicically inhibiting sulfation, resulted in the inhibition of PDAC cell proliferation and migration in vitro. TPST2-deficient MIA PaCa-2 cells showed inhibited xenograft tumor growth. Orthotopic inoculation of Tpst2 knockout KPC cells in mice showed inhibition of primary tumor growth, local invasion, and metastasis. Mechanistically, the integrin ß4 was found to be a novel substrate of TPST2. Inhibition of sulfation destabilizes integrin ß4 protein, which may have accounted for the suppression of metastasis. CONCLUSIONS: Targeting the SLC35B2-TPST2 axis of tyrosine sulfation may represent a novel approach for therapeutic intervention of PDAC.