hsa_circ_0000518 stimulates the malignant progression of hepatocellular carcinoma via regulating ITGA5 to activate the Warburg effect.

Studies have shown that the abnormal expression of circular RNA (circRNA) is inextricably linked to hepatocellular carcinoma (HCC). Recently, hsa_circ_0000518 (circ_0000518) was discovered in many cancer progressions. However, its function in HCC is still unclear. Through GEO database analysis combined with gene expression detection of HCC related clinical samples and cell lines, we identified that circ_0000518 was abnormally overexpressed in HCC. Cell and animal model experiments jointly indicated that circ_0000518 can stimulate HCC cell proliferation, migration, invasion and suppress apoptosis. Furthermore, we also found that knocking down the circ_0000518 could inhibit the Warburg effect in HCC cells. Mechanistically, circ_0000518 was found to be primarily localized in the cytoplasm, and sponge hsa-miR-326 (miR-326) promoted integrin alpha 5 (ITGA5) expression. In addition, circ_0000518 could enhance the stability of HuR-mediated ITGA5 mRNA, thereby activating the Warburg effect. In conclusion, this study elucidated that circ_0000518 was a cancer-promoting circRNA, which could enhance ITGA5 expression through competing endogenous RNAs (ceRNA) and RNA Binding Protein (RBP) mechanisms, thus facilitating the development of HCC. It provides a meaningful diagnostic and therapeutic target for HCC.

Enhancing Vasculogenesis in Dental Pulp Development: DPSCs-ECs Communication via FN1-ITGA5 Signaling.

BACKGROUND: Dental pulp regeneration therapy is a challenge to achieve early vascularization during treatment. Studying the regulatory mechanisms of vascular formation during human dental pulp development may provide insights for related therapies. In this study, we utilized single-cell sequencing analysis to compare the gene expression of dental pulp stem cells (DPSCs) and vascular endothelial cells (ECs) from developing and mature dental pulps. METHOD: Immunohistochemistry, Western blot, and real-time polymerase chain reaction (RT-PCR) were used to detect fibronectin 1 (FN1) expression and molecules, such as PI3K/AKT. Cell proliferation assay, scratch assay, tube formation assay and were used to investigate the effects of DPSCs on the vasculogenetic capability of ECs. Additionally, animal experiments involving mice were conducted. RESULT: The results revealed that DPSCs exist around dental pulp vasculature. FN1 expression was significantly higher in DPSCs from young permanent pulps than mature pulps, promoting HUVEC proliferation, migration, and tube formation via ITGA5 and the downstream PI3K/AKT signaling pathway. CONCLUSION: Our data indicate that intercellular communication between DPSCs and ECs mediated by FN1-ITGA5 signaling is crucial for vascularizationduring dental pulp development, laying an experimental foundation for future clinical studies.

Novel TCF21high pericyte subpopulation promotes colorectal cancer metastasis by remodelling perivascular matrix.

OBJECTIVE: Haematogenous dissemination is a prevalent route of colorectal cancer (CRC) metastasis. However, as the gatekeeper of vessels, the role of tumour pericytes (TPCs) in haematogenous metastasis remains largely unknown. Here, we aimed to investigate the heterogeneity of TPCs and their effects on CRC metastasis. DESIGN: TPCs were isolated from patients with CRC with or without liver metastases and analysed by single-cell RNA sequencing (scRNA-seq). Clinical CRC specimens were collected to analyse the association between the molecular profiling of TPCs and CRC metastasis. RNA-sequencing, chromatin immunoprecipitation-sequencing and bisulfite-sequencing were performed to investigate the TCF21-regulated genes and mechanisms underlying integrin α5 on TCF21 DNA hypermethylation. Pericyte-conditional Tcf21-knockout mice were constructed to investigate the effects of TCF21 in TPCs on CRC metastasis. Masson staining, atomic force microscopy, second-harmonic generation and two-photon fluorescence microscopy were employed to observe perivascular extracellular matrix (ECM) remodelling. RESULTS: Thirteen TPC subpopulations were identified by scRNA-seq. A novel subset of TCF21high TPCs, termed 'matrix-pericytes', was associated with liver metastasis in patients with CRC. TCF21 in TPCs increased perivascular ECM stiffness, collagen rearrangement and basement membrane degradation, establishing a perivascular metastatic microenvironment to instigate colorectal cancer liver metastasis (CRCLM). Tcf21 depletion in TPCs mitigated perivascular ECM remodelling and CRCLM, whereas the coinjection of TCF21high TPCs and CRC cells markedly promoted CRCLM. Mechanistically, loss of integrin α5 inhibited the FAK/PI3K/AKT/DNMT1 axis to impair TCF21 DNA hypermethylation in TCF21high TPCs. CONCLUSION: This study uncovers a previously unidentified role of TPCs in haematogenous metastasis and provides a potential diagnostic marker and therapeutic target for CRC metastasis.

The members of the miR-148/152 family inhibit cancer stem cell-like properties in gastric cancer via negative regulation of ITGA5.

BACKGROUND: The role of microRNA (miRNA) in modulating the function of cancer stem cells through diverse signaling pathway has been evidenced. We here identified a role of microRNA (miRNA) family, specifically miR-148/152, in gastric cancer and delineated its functional effects on gastric cancer stem cells. METHODS: Bioinformatics analysis was conducted to analyze expression of integrin α5 (ITGA5) which was verified through expression determination in clinical tissue samples. Next, the upstream regulatory factors of ITGA5 were determined. CD44+EpCAM (high) cells sorted from AGS cells subjected to gain-of-function experiments, followed by evaluation of their capacity of colony formation, generation of tumorosphere, cell migration and viability in vitro and xenograft tumor formation in vivo. RESULTS: ITGA5 was elevated in gastric cancer tissues and confirmed as a target gene of the miR-148/152 family members. The miR-148/152 family members were downregulated in gastric cancer tissues and cells. Decreased expression of miR-148/152 family members was also detected in gastric cancer stem cells. However, the raised expression led to reduced colony formation, tumorosphere, cell migration, cell viability, and drug resistance of CD44+EpCAM (high) AGS cells in vitro, and tumorigenesis in vitro. ITGA5 overexpression reversed the effect of the miR-148/152 family members. CONCLUSIONS: This study demonstrates that the miR-148/152 family members may prevent gastric cancer stem cell-like properties by targeting ITGA5, which can serve as an appealing target for gastric cancer treatment.

FGA inhibits metastases and induces autophagic cell death in gastric cancer via inhibiting ITGA5 to regulate the FAK/ERK pathway.

This study aims to investigate the expression levels of fibrinogen α chain (FGA) in human gastric cancer (GC) tissues and cell lines, clarify its role in gastric cancer progression, and explore its underlying mechanism. Bioinformatics analysis, Immunoblot, Immunohistochemical (IHC), and quantitative PCR assays were performed to assess the expression of FGA in human gastric cancer tissues and cell lines. CCK-8 and colony formation assays were performed to detect its role in the proliferation of gastric cancer cells. Wound healing, transwell, and Immunofluorescence were performed to detect its effects on gastric cancer cell motility and epithelial-mesenchymal transition (EMT) processes. Luciferase and CHIP assays were performed to confirm the transcriptional regulation of FGA on ITGA5. Immunoblot assays and double-label RFP-GFP-LC3 immunofluorescence analysis were conducted to detect its effects on gastric cancer cell autophagy and FAK/ERK pathway, and in vivo tumor growth assays were further performed. We found the low expression of FGA in human gastric cancer tissues and cell lines. FGA suppressed gastric cancer cell proliferation, motility, and EMT process, and stimulated cell autophagy. We further found that FGA suppressed the expression of Integrin-α5 (ITGA5) and inhibited the FAK/ERK pathway, therefore suppressing the progression of gastric cancer. The in vivo assays further confirmed that FGA suppressed tumor growth of gastric cancer cells in the BALB/c nude mice (18-22 g, female, 8-week-old) through suppressing ITGA5-mediated FAK/ERK pathway in mice. We demonstrated the mechanism underlying FGA suppressing gastric cancer progression, and therefore we thought FGA could serve as a tumor suppressor protein in gastric cancer.

Integrin α5 mediates intrinsic cisplatin resistance in three-dimensional nasopharyngeal carcinoma spheroids via the inhibition of phosphorylated ERK /caspase-3 induced apoptosis.

Nasopharyngeal carcinoma (NPC) originates in the nasopharynx epithelium. Although concurrent chemoradiation therapy followed by chemotherapy is considered as an effective treatment, there is substantial drug resistance in locally advanced NPC patients. One major contributor to the chemoresistance includes aberrant expression of cell adhesion molecules, such as integrin α and ß subunits, giving rise to cell adhesion-mediated drug resistance. Thus, the aim of this study was to investigate the effect of integrin α5 on the development of intrinsic cisplatin resistance in NPC and the associated underlying mechanisms using in vitro three-dimensional (3D) spheroid models, as well as induced cisplatin-resistant NPC (NPCcisR). We demonstrated that established 3D highly- (5-8F) and lowly- (6-10B) metastatic NPC spheroids overexpressed integrin α5 and aggravated their resistance to cisplatin. Besides, enhanced integrin α5 resulted in substantially reduced growth, corresponding to G0/G1 and G2/M cell cycle arrest. In addition, 5-8FcisR and 6-10BcisR cells in 3D forms synergistically strengthened endurance of their spheroids to cisplatin treatment as observed by increased resistance index (RI) and decreased apoptosis. Mechanistically, the aberrantly expressed integrin α5 decreased drug susceptibility in NPC spheroids by inactivating ERK and inhibition of caspase-3 inducing apoptosis. Furthermore, the effect of integrin α5 inducing intrinsic resistance was verified via treatment with ATN-161, a peptide inhibitor for integrin α5ß1. The results showed dramatic reduction in integrin α5 expression, reversal of ERK phosphorylation and caspase-3 cleavage, together with elevated cisplatin sensitivity, indicating regulation of innate drug resistance via integrin α5. Taken together, our findings suggest that integrin α5 could act as a promising target to enhance the chemotherapeutic sensitivity in NPC.

Expression and purification of a recombinant ELRL-MAP30 with dual-targeting anti-tumor bioactivity.

MAP30 (Momordica antiviral protein 30kD) is a single-chain Ⅰ-type ribosome inactivating protein with a variety of biological activities, including anti-tumor ability. It was reported that MAP30 would serve as a novel and relatively safe agent for prophylaxis and treatment of liver cancer. To determine whether adding two tumor targeting peptides could improve the antitumor activities of MAP30, we genetically modified MAP30 with an RGD motif and a EGFRi motif, which is a ligand with high affinity for αvß3 integrins and with high affinity for EGFR. The recombinant protein ELRL-MAP30 (rELRL-MAP30) containing a GST-tag was expressed in E. coli. The rELRL-MAP30 was highly expressed in the soluble fraction after induction with 0.15 mM IPTG for 20 h at 16 °C. The purified rELRL-MAP30 appeared as a band on SDS-PAGE. It was identified by western blotting. Cytotoxicity of recombinant protein to HepG2, MDA-MB-231, HUVEC and MCF-7 cells was detected by MTT analysis. Half maximal inhibitory concentration (IC50) values were 54.64 µg/mL, 70.13 µg/mL, 146 µg/mL, 466.4 µg/mL, respectively. Proliferation inhibition assays indicated that rELRL-MAP30 could inhibit the growth of Human liver cancer cell HepG2 effectively. We found that rELRL-MAP30 significantly induced apoptosis in liver cancer cells, as evidenced by nuclear staining of DAPI. In addition, rELRL-MAP30 induced apoptosis in human liver cancer HepG2 cells by up-regulation of Bax as well as down-regulation of Bcl-2. Migration of cell line were markedly inhibited by rELRL-MAP30 in a dose-dependent manner compared to the recombinant MAP30 (rMAP30). In summary, the fusion protein displaying extremely potent cytotoxicity might be highly effective for tumor therapy.

Niche-Mediated Integrin Signaling Supports Steady-State Hematopoiesis in the Spleen.

Outside-in integrin signaling regulates cell fate decisions in a variety of cell types, including hematopoietic stem cells (HSCs). Our earlier published studies showed that interruption of periostin (POSTN) and integrin-αv (ITGAV) interaction induces faster proliferation in HSCs with developmental stage-dependent functional effects. In this study, we examined the role of POSTN-ITGAV axis in lymphohematopoietic activity in spleen that hosts a rare population of HSCs, the functional regulation of which is not clearly known. Vav-iCre-mediated deletion of Itgav in the hematopoietic system led to higher proliferation rates, resulting in increased frequency of primitive HSCs in the adult spleen. However, in vitro CFU-C assays demonstrated a poorer differentiation potential following Itgav deletion. This also led to a decrease in the white pulp area with a significant decline in the B cell numbers. Systemic deletion of its ligand, POSTN, phenocopied the effects noted in Vav-Itgav-/- mice. Histological examination of Postn-deficient spleen also showed an increase in the spleen trabecular areas. Importantly, these are the myofibroblasts of the trabecular and capsular areas that expressed high levels of POSTN within the spleen tissue. In addition, vascular smooth muscle cells also expressed POSTN. Through CFU-S12 assays, we showed that hematopoietic support potential of stroma in Postn-deficient splenic hematopoietic niche was defective. Overall, we demonstrate that POSTN-ITGAV interaction plays an important role in spleen lymphohematopoiesis.

High mobility group nucleosomal binding 2 reduces integrin α5/ß1-mediated adhesion of Klebsiella pneumoniae on human pulmonary epithelial cells via nuclear factor I.

It has been reported that high mobility group nucleosomal binding domain 2 (HMGN2) is a nucleus-related protein that regulates gene transcription and plays a critical role in bacterial clearance. An elevated level of HMGN2 reduced integrin α5/ß1 expression of human pulmonary epithelial A549 cells was demonstrated during Klebsiella pneumoniae infection, thus weakening bacterial adhesion and invasion. However, the mechanism by which HMGN2 regulates integrin expression remains unclear. This study found that a transcription factor-nuclear factor I (NFI), which serves as the potential target of HMGN2 regulated integrin expression. The results showed that HMGN2 was able to promote NFIA and NFIB expression by increasing H3K27 acetylation of NFIA/B promoter regions. The integrin α5/ß1 expression was significantly enhanced by knockdown of NFIA/B via a siRNA approach. Meanwhile, NFIA/B silence could also compromise the inhibition effect of HMGN2 on the integrin α5/ß1 expression. Mechanistically, it was demonstrated that HMGN2 facilitated the recruitment of NFI on the promoter regions of integrin α5/ß1 according to the chromatin immunoprecipitation assay. In addition, it was further demonstrated that the knockdown of NFIA/B induced more adhesion of Klebsiella pneumoniae on pulmonary epithelial A549 cells, which could be reversed by the application of an integrin inhibitor RGD. The results revealed a regulatory role of HMGN2 on the transcription level of integrin α5/ß1, indicating a potential treatment strategy against Klebsiella pneumoniae-induced infectious lung diseases.

Hypoxia-autophagy axis induces VEGFA by peritoneal mesothelial cells to promote gastric cancer peritoneal metastasis through an integrin α5-fibronectin pathway.

BACKGROUND: Peritoneal metastasis (PM) is an important pathological process in the progression of gastric cancer (GC). The metastatic potential of tumor and stromal cells is governed by hypoxia, which is a key molecular feature of the tumor microenvironment. Mesothelial cells also participate in this complex and dynamic process. However, the molecular mechanisms underlying the hypoxia-driven mesothelial-tumor interactions that promote peritoneal metastasis of GC remain unclear. METHODS: We determined the hypoxic microenvironment in PM of nude mice by immunohistochemical analysis and screened VEGFA by human growth factor array kit. The crosstalk mediated by VEGFA between peritoneal mesothelial cells (PMCs) and GC cells was determined in GC cells incubated with conditioned medium prepared from hypoxia-treated PMCs. The association between VEGFR1 and integrin α5 and fibronectin in GC cells was enriched using Gene Set Enrichment Analysis and KEGG pathway enrichment analysis. In vitro and xenograft mouse models were used to evaluate the impact of VEGFA/VEGFR1 on gastric cancer peritoneal metastasis. Confocal microscopy and immunoprecipitation were performed to determine the effect of hypoxia-induced autophagy. RESULTS: Here we report that in the PMCs of the hypoxic microenvironment, SIRT1 is degraded via the autophagic lysosomal pathway, leading to increased acetylation of HIF-1α and secretion of VEGFA. Under hypoxic conditions, VEGFA derived from PMCs acts on VEGFR1 of GC cells, resulting in p-ERK/p-JNK pathway activation, increased integrin α5 and fibronectin expression, and promotion of PM. CONCLUSIONS: Our findings have elucidated the mechanisms by which PMCs promote PM in GC in hypoxic environments. This study also provides a theoretical basis for considering autophagic pathways or VEGFA as potential therapeutic targets to treat PM in GC.

Adhesion to fibronectin via α5ß1 integrin supports expansion of the megakaryocyte lineage in primary myelofibrosis.

Excessive accumulation of extracellular matrix (ECM) is a hallmark of bone marrow (BM) milieu in primary myelofibrosis (PMF). Because cells have the ability to adhere to the surrounding ECM through integrin receptors, we examined the hypothesis that an abnormal ECM-integrin receptor axis contributes to BM megakaryocytosis in JAK2V617F+ PMF. Secretion of ECM protein fibronectin (FN) by BM stromal cells from PMF patients correlates with fibrosis and disease severity. Here, we show that Vav1-hJAK2V617F transgenic mice (JAK2V617F+) have high BM FN content associated with megakaryocytosis and fibrosis. Further, megakaryocytes from JAK2V617F+ mice have increased cell surface expression of the α5 subunit of the α5ß1 integrin, the major FN receptor in megakaryocytes, and augmented adhesion to FN compared with wild-type controls. Reducing adhesion to FN by an inhibitory antibody to the α5 subunit effectively reduces the percentage of CD41+ JAK2V617F+ megakaryocytes in vitro and in vivo. Corroborating our findings in mice, JAK2V617F+ megakaryocytes from patients showed elevated expression of α5 subunit, and a neutralizing antibody to α5 subunit reduced adhesion to FN and megakaryocyte number derived from CD34+ cells. Our findings reveal a previously unappreciated contribution of FN-α5ß1 integrin to megakaryocytosis in JAK2V617F+ PMF.

Calcium deficient placental growth restriction is mediated by an increase in non-invasive integrin α5 and ß4 phenotype.

OBJECTIVES: Integrins are cell adhesion receptors that participated in endovascular invasion by cytotrophoblasts in preeclampsia. This study aimed to investigate the effect of calcium on cellular pathways influencing the trophoblast integration into endothelial cellular networks in vitro. STUDY DESIGN: Red fluorescent-labelled human uterine myometrial microvascular endothelial cells (UtMVECs) were seeded on Matrigel. Green fluorescent-labelled HTR-8/SVneo trophoblast cells were then co-cultured with endothelial cells in different concentrations of calcium for 24 h. MAIN OUTCOME MEASURES: The calcium effects on HTR-8/SVneo cell integration were quantified by Image J. Quantitative PCR was performed to measure mRNA expression of integrins α1, α5, α6, ß1 and ß4. The concentrations of interleukin IL-6, matrix metalloproteinase-2 (MMP-2), MMP-9, PlGF and sFlt-1 in the conditioned medium were measured by ELISA while levels of cytokines IL-1ß, IL-8, IL-10, TNF-α and INF-γ were assessed by magnetic Luminex assays™. RESULTS: Both calcium depletion (0.4 mM) and low calcium (1.8 mM) groups demonstrated inhibited integration of trophoblast cells into endothelial cellular networks, compared with the normal calcium group (2.4 mM). The IL-6 production was reduced from conditioned media in both calcium depletion and low calcium groups. In calcium depletion group, mRNA expression of integrin α5 and ß4 in trophoblasts was increased while integrin α1 was decreased. CONCLUSIONS: The in vitro trophoblast cell integration into endothelial cellular networks could be modified by altering media calcium through integrin switch away from integrins α5 and ß4 and towards integrin α1 which may be required for healthy early trophoblast integration.

Reappraising the role of α5 integrin and the microenvironmental support in stress erythropoiesis.

We previously studied the role of ß1 integrin and some of its different α partners relevant to erythropoiesis. Although clear and consistent answers regarding the role of α4ß1 (VLA-4) were evident, the role of its companion integrin α5ß1 (VLA-5) was clouded by inconsistent outcomes in all prior publications. Furthermore, the functional consequences of integrin deficiencies only in microenvironmental (ME) cells supporting erythroid cell expansion and maturation post stress have never been explored. In the study described here, we created several additional mouse models in the aim of addressing unanswered questions regarding functional consequences of single or combined integrin deficiencies in erythroid cells or only in ME supporting cells. Our novel and expansive data solidified the intrinsic requirement of both α4 and α5 integrins in erythroid cells for their proliferative expansion and maturation in response to stress; α5 integrin alone, deleted either early in all hematopoietic cells or only in erythroid cell, has only a redundant role in proliferative expansion and is dispensable for erythroid maturation. By contrast, α4 integrin, on its own, exerts a dominant effect on timely and optimal erythroid maturation. Deficiency of both α4 and α5 integrins in ME cells, including macrophages, does not negatively influence stress response by normal erythroid cells, in great contrast to the effect of ME cells deficient in all ß1 integrins. Collectively the present data offer deeper insight into the coordination of different ß1 integrin functional activities in erythroid cells or in ME cells for optimal erythroid stress response.

EpCAM associates with integrin and regulates cell adhesion in cancer cells.

The epithelial cell adhesion molecule (EpCAM) is one of the most frequently and intensely expressed of tumor-associated antigens, but the role that EpCAM plays in the proliferation, adhesion and migration properties of cancer cells remains unclear. In the present study, we screened several tumor cell lines and found that colorectal cancer CW-2 and epidermoid carcinoma A431 cells expressed relatively higher levels of EpCAM. In order to assess the biological functions of EpCAM expression in cell adhesion and migration, we established a knock out (KO) of EpCAM genes in both of these types of cancer cells via a CRISPR/Cas9 system. The elongated cell morphology was converted to a rounded morphology in the EpCAM-KO cells. These cells showed decreases in cell proliferation and migration into extracellular matrix proteins, as well as decreases in cellular signaling elements such as phosphorylated focal adhesion kinase (FAK), AKT and ERK. Moreover, the cell growth and the colony formation abilities were significantly decreased in EpCAM-KO cells. Importantly, co-immunoprecipitation analysis revealed that EpCAM associated with integrin ß1. Also, the expression levels of integrin α5 were decreased in EpCAM-KO cells, compared with that in the wild-type cells. Taken together, these data clearly demonstrate that EpCAM associates with integrin ß1 to regulate FAK/ERK signaling pathways in controlling cell adhesion, migration and proliferation via extracellular matrix adhesion, which provides novel mechanisms for EpCAM-mediated biological functions and cancer phenotypes.

Fibronectin Promotes Cell Growth and Migration in Human Renal Cell Carcinoma Cells.

The prognostic and therapeutic values of fibronectin have been reported in patients with renal cell carcinoma (RCC). However, the underlying mechanisms of malignancy in RCC are not completely understood. We found that silencing of fibronectin expression attenuated human RCC 786-O and Caki-1 cell growth and migration. Silencing of potential fibronectin receptor integrin α5 and integrin ß1 decreased 786-O cell ability in movement and chemotactic migration. Biochemical examination revealed a reduction of cyclin D1 and vimentin expression, transforming growth factor-ß1 (TGF-ß1) production, as well as Src and Smad phosphorylation in fibronectin-silenced 786-O and Caki-1 cells. Pharmacological inhibition of Src decreased 786-O cell growth and migration accompanied by a reduction of cyclin D1, fibronectin, vimentin, and TGF-ß1 expression, as well as Src and Smad phosphorylation. In 786-O cells, higher activities in cell growth and migration than in Caki-1 cells were noted, along with elevated fibronectin and TGF-ß1 expression. The additions of exogenous fibronectin and TGF-ß1 promoted Caki-1 cell growth and migration, and increased cyclin D1, fibronectin, vimentin, and TGF-ß1 expression, as well as Src and Smad phosphorylation. These findings highlight the role of fibronectin in RCC cell growth and migration involving Src and TGF-ß1 signaling.

Human mesenchymal stem cells promote tumor growth via MAPK pathway and metastasis by epithelial mesenchymal transition and integrin α5 in hepatocellular carcinoma.

Mesenchymal stem cells (MSCs) appear to be a potential vehicle for anticancer drugs due to their excellent tumor tropism ability. However, the interactions between MSCs and hepatocellular carcinoma (HCC) are quite controversial and the underlying mechanisms are ambiguous. In this study, an investigation was conducted into the effect of human MSCs (hMSCs) on tumor proliferation and metastasis both in xenograft and orthotopic models. It was discovered that hMSCs could promote tumor growth though activating mitogen-activated protein kinase (MAPK) signaling pathway and promote metastasis by epithelial mesenchymal transition (EMT) in vivo. To test whether hMSCs could induce immunosuppressive effects, the expression of the Natural killer (NK) cell marker CD56 was measured by immunohistochemical staining and the expression of interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α) were measured by qRT-PCR. It was found out that CD56 expression significantly decreased, while TNF-α and IL-6 expression increased in the hMSCs-treated tissues. Mechanistically, RNA sequencing was performed, which led to a discovery that integrin α5 (ITGA5) was over-expressed in hMSCs-treated HCC. ITGA5 siRNAs blocked the hMSCs-induced migration and invasion of HCC, while over-expression of ITGA5 promoted the migration and invasion ability in HCC-hMSCs, indicating that the expression of ITGA5 is associated with hMSCs-induced tumor metastasis. These findings suggest that hMSCs may play a vital role in HCC proliferation and metastasis and could be identified as a putative therapeutic target in HCC.

Alpha-5 Integrin Mediates Simvastatin-Induced Osteogenesis of Bone Marrow Mesenchymal Stem Cells.

Simvastatin (SVS) promotes the osteogenic differentiation of mesenchymal stem cells (MSCs) and has been studied for MSC-based bone regeneration. However, the mechanism underlying SVS-induced osteogenesis is not well understood. We hypothesize that α5 integrin mediates SVS-induced osteogenic differentiation. Bone marrow MSCs (BMSCs) derived from BALB/C mice, referred to as D1 cells, were used. Alizarin red S (calcium deposition) and alkaline phosphatase (ALP) staining were used to evaluate SVS-induced osteogenesis of D1 cells. The mRNA expression levels of α5 integrin and osteogenic marker genes (bone morphogenetic protein-2 (BMP-2), runt-related transcription factor 2 (Runx2), collagen type I, ALP and osteocalcin (OC)) were detected using quantitative real-time PCR. Surface-expressed α5 integrin was detected using flow cytometry analysis. Protein expression levels of α5 integrin and phosphorylated focal adhesion kinase (p-FAK), which is downstream of α5 integrin, were detected using Western blotting. siRNA was used to deplete the expression of α5 integrin in D1 cells. The results showed that SVS dose-dependently enhanced the gene expression levels of osteogenic marker genes as well as subsequent ALP activity and calcium deposition in D1 cells. Upregulated p-FAK was accompanied by an increased protein expression level of α5 integrin after SVS treatment. Surface-expressed α5 integrin was also upregulated after SVS treatment. Depletion of α5 integrin expression significantly suppressed SVS-induced osteogenic gene expression levels, ALP activity, and calcium deposition in D1 cells. These results identify a critical role of α5 integrin in SVS-induced osteogenic differentiation of BMSCs, which may suggest a therapeutic strategy to modulate α5 integrin/FAK signaling to promote MSC-based bone regeneration.

Does blastomere removal alter the expression level of miR-Let7a and its target genes following mouse embryo biopsy?

Embryo manipulations may cause the misexpression of various genes, most of which play critical roles in the regulation of implantation. This study aimed to evaluate the effects of embryo biopsy on the expression of miR-Let-7a and its gene targets including ErbB4, Tgf-α, Itg-αv, Itg ß3 on the implantation of mouse embryo. Embryos were produced by in vitro fertilization followed by blastomere biopsy at the eight-cell stage. The effects of blastomere removal on the expression of genes ErbB4, Tgf-α, Itg αv, Itg ß3, and miR-Let-7a as well as the alteration of the blastocyst cell number were compared in both biopsied and non-biopsied groups. Finally, blastocyst attachment was assessed on culture dishes precoated with Fibronectin. The results revealed that there were no significant differences between the biopsied and non-biopsied embryos with reference to the blastocyst formation rates, the average inner cell mass, trophectoderm cell number, and percentage of attachment of blastocysts (P > 0.05). The expression of ErbB4, Itg-ß3, Itg-αv, TGF-α transcripts, and miR-Let-7a in blastocysts biopsied embryos did not differ from the non-biopsied blastocysts (P > 0.05). The results demonstrated that the preimplantation embryo development and attachment of biopsied embryos in vitro is not adversely affected by one blastomere biopsy at the eight-cell stage embryo.

CagY-Dependent Regulation of Type IV Secretion in Helicobacter pylori Is Associated with Alterations in Integrin Binding.

Strains of Helicobacter pylori that cause ulcer or gastric cancer typically express a type IV secretion system (T4SS) encoded by the cag pathogenicity island (cagPAI). CagY is an ortholog of VirB10 that, unlike other VirB10 orthologs, has a large middle repeat region (MRR) with extensive repetitive sequence motifs, which undergo CD4+ T cell-dependent recombination during infection of mice. Recombination in the CagY MRR reduces T4SS function, diminishes the host inflammatory response, and enables the bacteria to colonize at a higher density. Since CagY is known to bind human α5ß1 integrin, we tested the hypothesis that recombination in the CagY MRR regulates T4SS function by modulating binding to α5ß1 integrin. Using a cell-free microfluidic assay, we found that H. pylori binding to α5ß1 integrin under shear flow is dependent on the CagY MRR, but independent of the presence of the T4SS pili, which are only formed when H. pylori is in contact with host cells. Similarly, expression of CagY in the absence of other T4SS genes was necessary and sufficient for whole bacterial cell binding to α5ß1 integrin. Bacteria with variant cagY alleles that reduced T4SS function showed comparable reduction in binding to α5ß1 integrin, although CagY was still expressed on the bacterial surface. We speculate that cagY-dependent modulation of H. pylori T4SS function is mediated by alterations in binding to α5ß1 integrin, which in turn regulates the host inflammatory response so as to maximize persistent infection.IMPORTANCE Infection with H. pylori can cause peptic ulcers and is the most important risk factor for gastric cancer, the third most common cause of cancer death worldwide. The major H. pylori virulence factor that determines whether infection causes disease or asymptomatic colonization is the type IV secretion system (T4SS), a sort of molecular syringe that injects bacterial products into gastric epithelial cells and alters host cell physiology. We previously showed that recombination in CagY, an essential T4SS component, modulates the function of the T4SS. Here we found that these recombination events produce parallel changes in specific binding to α5ß1 integrin, a host cell receptor that is essential for T4SS-dependent translocation of bacterial effectors. We propose that CagY-dependent binding to α5ß1 integrin acts like a molecular rheostat that alters T4SS function and modulates the host immune response to promote persistent infection.

Expression and characterization of αvß5 integrin on intestinal macrophages.

Macrophages play a crucial role in maintaining homeostasis in the intestine, but the underlying mechanisms have not yet been elucidated fully. Here, we show for the first time that mature intestinal macrophages in mouse intestine express high levels of αvß5 integrin, which acts as a receptor for the uptake of apoptotic cells and can activate molecules involved in several aspects of tissue homeostasis such as angiogenesis and remodeling of the ECM. αvß5 is not expressed by other immune cells in the intestine, is already present on intestinal macrophages soon after birth, and its expression is not dependent on the microbiota. In adults, αvß5 is induced during the differentiation of monocytes in response to the local environment and it confers intestinal macrophages with the ability to promote engulfment of apoptotic cells via engagement of the bridging molecule milk fat globule EGF-like molecule 8. In the absence of αvß5, there are fewer monocytes in the mucosa and mature intestinal macrophages have decreased expression of metalloproteases and IL 10. Mice lacking αvß5 on haematopoietic cells show increased susceptibility to chemical colitis and we conclude that αvß5 contributes to the tissue repair by regulating the homeostatic properties of intestinal macrophages.