Regulation of β1-integrin in autophagy and apoptosis of gastric epithelial cells infected with Helicobacter pylori

Knocking Down HN1 Blocks Helicobacter pylori-Induced Malignant Phenotypes in Gastric Mucosal Cells and Inhibits Gastric Cancer Cell Proliferation, Cytoskeleton Remodeling, and Migration

Helicobacter pylori (H. pylori) is implicated in the aberrant proliferation and malignant transformation of gastric mucosal cells, heightening the risk of gastric cancer (GC). HN1 is involved in the development of various tumors. However, precise mechanistic underpinnings of HN1 promoting GC progression in H. pylori remain elusive. The study collected 79 tissue samples of GC patients, including 47 with H. pylori-positive GC and 32 H. pylori-negative controls. Using human gastric epithelial cells (GES-1) and human gastric adenocarcinoma cells (HGC-27), the effect of overexpression / knocking down of HN1 and H. pylori infection was evaluated on cell function (proliferation, migration, apoptosis), cytoskeleton, and expression of cell malignant phenotype factors that promote the malignant biological behavior of cancer cells. The expression of HN1 in GC tissues is higher than that in paracancerous tissue and is closely related to infiltration, lymphatic metastasis, distant metastasis, survival, and H. pylori infection. Downregulation of HN1 effectively hinders the ability of H. pylori strains 26695 and SS1 to promote migration of GES-1 and HGC-27 cells, while lowering the expression of key indicators associated with malignant phenotype. Downregulated GSK3B, β-catenin, and Vimentin after knockdown Integrinβ1, but HN1 expression remained largely unchanged, when HN1 and Integrinβ1 were knocked down, GSK3B, β-catenin, and Vimentin expression were considerably reduced. Our research demonstrated the crucial role of HN1 in H. pylori-induced acquisition of a malignant phenotype in GES-1 cells. Knockdown of HN1 blocked the pathogenic mechanism of H. pylori-induced GC and downregulated the expression of GSK3Β, β-catenin and Vimentin via Integrin β1.

Eliminating the invading extracellular and intracellular FnBp+ bacteria from respiratory epithelial cells by autophagy mediated through FnBp-Fn-Integrin α5β1 axis

Background

We previously found that the respiratory epithelial cells could eliminate the invaded group A streptococcus (GAS) through autophagy induced by binding a fibronectin (Fn) binding protein (FnBp) expressed on the surface of GAS to plasma protein Fn and its receptor integrin α5β1 of epithelial cells. Is autophagy initiated by FnBp+ bacteria via FnBp-Fn-Integrin α5β1 axis a common event in respiratory epithelial cells?

Methods

We chose Staphylococcus aureus (S. aureus/S. a) and Listeria monocytogenes (L. monocytogenes/L. m) as representatives of extracellular and intracellular FnBp+ bacteria, respectively. The FnBp of them was purified and the protein function was confirmed by western blot, viable bacteria count, confocal and pull-down. The key molecule downstream of the action axis was detected by IP, mass spectrometry and bio-informatics analysis.

Results

We found that different FnBp from both S. aureus and L. monocytogenes could initiate autophagy through FnBp-Fn-integrin α5β1 axis and this could be considered a universal event, by which host tries to remove invading bacteria from epithelial cells. Importantly, we firstly reported that S100A8, as a key molecule downstream of integrin β1 chain, is highly expressed upon activation of integrin α5β1, which in turn up-regulates autophagy.

Conclusions

Various FnBp from FnBp+ bacteria have the ability to initiate autophagy via FnBp-Fn-Integrin α5β1 axis to promote the removal of invading bacteria from epithelial cells in the presence of fewer invaders. S100A8 is a key molecule downstream of Integrin α5β1 in this autophagy pathway.

β1-Integrin plays a major role in resveratrol-mediated anti-invasion effects in the CRC microenvironment

Background: Tumor microenvironment (TME) is one of the most important factors in tumor aggressiveness, with an active exchange between tumor and other TME-associated cells that promotes metastasis. The tumor-inhibitory effect of resveratrol on colorectal cancer (CRC) cells has been frequently reported. However, whether resveratrol can specifically suppress TME-induced CRC invasion via β1-integrin receptors has not been fully elucidated yet.

Methods: Two CRC cell lines (HCT116, RKO) were cultured in multicellular, pro-inflammatory 3D-alginate TME cultures (containing fibroblasts, T-lymphocytes) to investigate the role of β1-integrin receptors in the anti-invasive and anti-metastatic effect of resveratrol by antisense oligonucleotides (ASO).

Results: Our results show that resveratrol dose-dependently suppressed the migration-promoting adhesion adapter protein paxillin and simultaneously enhanced the expression of E-cadherin associated with the phenotype change of CRC cells, and their invasion. Moreover, resveratrol blocked TME-induced phosphorylation and nuclear translocation of p65-NF-κB, which was associated with changes in the expression pattern of epithelial-mesenchymal-transition-related biomarkers (slug, vimentin, E-cadherin), metastasis-related factors (CXCR4, MMP-9, FAK), and apoptosis (caspase-3). Finally, transient transfection of β1-integrin, in contrast to knockdown of NF-κB, abrogated most anti-invasive, anti-metastatic effects as well as downstream signaling of resveratrol, resulting in a concomitant increase in CRC cell invasion, indicating a central role of β1-integrin receptors in the anti-invasive function of resveratrol.

Conclusion: These results demonstrate for the first time that silencing β1-integrins may suppress, at least in part the inhibitory effects of resveratrol on invasion and migration of CRC cells, underscoring the crucial homeostatic role of β1-integrin receptors.