Structural and Functional Insight Into the Glycosylation Impact Upon the HGF/c-Met Signaling Pathway

Pathogenic variants in HGF give rise to childhood-to-late onset primary lymphoedema by loss of function

Developmental and functional defects in the lymphatic system are responsible for primary lymphoedema (PL). PL is a chronic debilitating disease caused by increased accumulation of interstitial fluid, predisposing to inflammation, infections and fibrosis. There is no cure, only symptomatic treatment is available. Thirty-two genes or loci have been linked to PL, and another 22 are suggested, including Hepatocyte Growth Factor (HGF). We searched for HGF variants in 770 index patients from the Brussels PL cohort. We identified ten variants predicted to cause HGF loss-of-function (six nonsense, two frameshifts, and two splice-site changes; 1.3% of our cohort), and 14 missense variants predicted to be pathogenic in 17 families (2.21%). We studied co-segregation within families, mRNA stability for non-sense variants, and in vitro functional effects of the missense variants. Analyses of the mRNA of patient cells revealed degradation of the nonsense mutant allele. Reduced protein secretion was detected for nine of the 14 missense variants expressed in COS-7 cells. Stimulation of lymphatic endothelial cells with these 14 HGF variant proteins resulted in decreased activation of the downstream targets AKT and ERK1/2 for three of them. Clinically, HGF-associated PL was diverse, but predominantly bilateral in the lower limbs with onset varying from early childhood to adulthood. Finally, aggregation study in a second independent cohort underscored that rare likely pathogenic variants in HGF explain about 2% of PL. Therefore, HGF signalling seems crucial for lymphatic development and/or maintenance in human beings and HGF should be included in diagnostic genetic screens for PL.

Hepatocyte growth factor promotes retinal pigment epithelium cell activity through MET/AKT signaling pathway

AIM

To explore the effects of hepatocyte growth factor (HGF) on retinal pigment epithelium (RPE) cell behaviors.

METHODS

The human adult retinal pigment epithelial cell line-19 (ARPE-19) were treated by HGF or mesenchymal-epithelial transition factor (MET) inhibitor SU11274 in vitro. Cell viability was detected by a Cell Counting Kit-8 assay. Cell proliferation and motility was detected by a bromodeoxyuridine incorporation assay and a wound healing assay, respectively. The expression levels of MET, phosphorylated MET, protein kinase B (AKT), and phosphorylated AKT proteins were determined by Western blot assay. The MET and phosphorylated MET proteins were also determined by immunofluorescence assay.

RESULTS

HGF increased ARPE-19 cells' viability, proliferation and migration, and induced an increase of phosphorylated MET and phosphorylated AKT proteins. SU11274 significantly reduced cell viability, proliferation, and migration and decreased the expression of MET and AKT proteins. SU11274 suppressed HGF-induced increase of viability, proliferation, and migration in ARPE-19 cells. Additionally, SU11274 also blocked HGF-induced phosphorylation of MET and AKT proteins.

CONCLUSION

HGF enhances cellular viability, proliferation, and migration in RPE cells through the MET/AKT signaling pathway, whereas this enhancement is suppressed by the MET inhibitor SU11274. HGF-induced MET/AKT signaling might be a vital contributor of RPE cells survival.

Unlocking c-MET: A comprehensive journey into targeted therapies for breast cancer

Breast cancer is the most common malignancy among women, posing a formidable health challenge worldwide. In this complex landscape, the c-MET (cellular-mesenchymal epithelial transition factor) receptor tyrosine kinase (RTK), also recognized as the hepatocyte growth factor (HGF) receptor (HGFR), emerges as a prominent protagonist, displaying overexpression in nearly 50% of breast cancer cases. Activation of c-MET by its ligand, HGF, secreted by neighboring mesenchymal cells, contributes to a cascade of tumorigenic processes, including cell proliferation, metastasis, angiogenesis, and immunosuppression. While c-MET inhibitors such as crizotinib, capmatinib, tepotinib and cabozantinib have garnered FDA approval for non-small cell lung cancer (NSCLC), their potential within breast cancer therapy is still undetermined. This comprehensive review embarks on a journey through structural biology, multifaceted functions, and intricate signaling pathways orchestrated by c-MET across cancer types. Furthermore, we highlight the pivotal role of c-MET-targeted therapies in breast cancer, offering a clinical perspective on this promising avenue of intervention. In this pursuit, we strive to unravel the potential of c-MET as a beacon of hope in the fight against breast cancer, unveiling new horizons for therapeutic innovation.

Sialyltransferase ST3GAL4 confers osimertinib resistance and offers strategies to overcome resistance in non-small cell lung cancer

The third-generation EGFR-TKI osimertinib is widely used in EGFR-mutated positive non-small cell lung cancer (NSCLC) patients, but drug resistance is inevitable. The currently known mechanisms only explain resistance in a small proportion of patients. For most patients, the mechanism of osimertinib resistance is still unclear, especially for EGFR-independent resistance. Herein, we thoroughly investigated the novel mechanism of osimertinib resistance and treatment strategies. We identified that ST3GAL4, a sialyltransferase, catalyzes terminal glycan sialylation of receptor protein tyrosine kinases, which induces acquired resistance to osimertinib in vitro and in vivo. In addition, ST3GAL4 is generally overexpressed in osimertinib-resistant patients with unknown resistance mechanisms. ST3GAL4 modifies MET glycosylation on N785 with sialylation, which antagonizes K48-related ubiquitin-dependent MET degradation and subsequently activates MET and its downstream proliferation signaling pathways. Meanwhile, ST3GAL4 knockdown or inhibition by brigatinib resensitizes resistant non-small cell lung cancer cells to osimertinib in vitro and in vivo This study suggests that ST3GAL4 can induce acquired resistance to osimertinib, which may be an important EGFR-independent resistance mechanism Furthermore, targeting ST3GAL4 with brigatinib provides new strategies to overcome osimertinib resistance.

Suppression of galectin-4 attenuates peritoneal metastasis of poorly differentiated gastric cancer cells

BACKGROUND

Peritoneal dissemination, most often seen in metastatic and/or recurrent gastric cancer, is an inoperable condition that lacks effective treatment. The use of molecular targeted drugs is also limited; therefore, identifying novel therapeutic targets and improving our understanding of this metastatic cancer are an urgent requirement. In this study, we focused on galectin-4, which is specifically expressed in poorly differentiated cells with high potential for peritoneal dissemination.

METHODS

We knocked out the galectin-4 gene in NUGC4 cells using CRISPR/Cas9-mediated genome editing. Proliferation and peritoneal cancer formation in knockout cells were compared with those in wild-type and galectin-4 re-expressing cells. Western blotting and proximity ligation assays were performed to identify associated molecules affected by the expression of galectin-4. The effect of galectin-4 knockdown on cell proliferation and peritoneal metastasis was studied using a specific siRNA. Expression of galectin-4 in peritoneal metastatic tumors from 10 patients with gastric cancer was examined by immunohistochemistry.

RESULTS

Suppression of galectin-4 expression reduced proliferation and peritoneal metastasis of malignant gastric cancer cells. Galectin-4 knockout and knockdown reduced the expression of activated c-MET and CD44. Galectin-4 was found to interact with several proteins on the cell surface, including CD44 and c-MET, via its carbohydrate-binding ability. Immunohistochemistry showed galectin-4 expression in peritoneal metastatic tumor cells in all patients examined.

CONCLUSIONS

We clarified the role of galectin-4 in the development of peritoneal dissemination of poorly differentiated gastric cancer cells. Our data highlight the diagnostic and therapeutic potential of galectin-4 in the peritoneal dissemination of gastric cancer.

Bone marrow mesenchymal stem cells in premature ovarian failure: Mechanisms and prospects

Premature ovarian failure (POF) is a common female reproductive disorder and characterized by menopause, increased gonadotropin levels and estrogen deficiency before the age of 40 years old. The etiologies and pathogenesis of POF are not fully clear. At present, hormone replacement therapy (HRT) is the main treatment options for POF. It helps to ameliorate perimenopausal symptoms and related health risks, but can't restore ovarian function and fertility fundamentally. With the development of regenerative medicine, bone marrow mesenchymal stem cells (BMSCs) have shown great potential for the recovery of ovarian function and fertility based on the advantages of abundant sources, high capacity for self-renewal and differentiation, low immunogenicity and less ethical considerations. This systematic review aims to summarize the possible therapeutic mechanisms of BMSCs for POF. A detailed search strategy of preclinical studies and clinical trials on BMSCs and POF was performed on PubMed, MEDLINE, Web of Science and Embase database. A total of 21 studies were included in this review. Although the standardization of BMSCs need more explorations, there is no doubt that BMSCs transplantation may represent a prospective therapy for POF. It is hope to provide a theoretical basis for further research and treatment for POF.

A novel anti-lung cancer agent inhibits proliferation and epithelial-mesenchymal transition

OBJECTIVE

To synthesize a novel chalcone-1,3,4-thiadiazole hybrid and investigate its anticancer effects against NCI-H460 cells.

METHODS

(E)-3-(4-bromophenyl)-1-(4-hydroxyphenyl)prop-2-en-1-one, 1,3-dibromopropane and 1,3,4-thiadiazole-2-thiol were used as chemical materials to synthesize compound ZW97. The NCI-H460 lung cancer cell line was selected to explore the antitumor effects of compound ZW97 in vitro and in vivo.

RESULTS

Compound ZW97 selectively inhibited cell proliferation against lung cancer cell lines NCI-H460, HCC-44 and NCI-H3122 with IC₅₀ values of 0.15 μM, 2.06 μM and 1.17 μM, respectively. ZW97 suppressed migration and the epithelial-mesenchymal transition process in NCI-H460 cells in a concentration-dependent manner. Based on the kinase activity results and docking analysis, compound ZW97 is a novel tyrosine-protein kinase Met (c-Met kinase) inhibitor. It also inhibited NCI-H460 cell growth in xenograft models without obvious toxicity to normal tissues.

CONCLUSIONS

Compound ZW97 is a potential c-Met inhibitor that might be a promising agent to treat lung cancer by inhibiting the epithelial-mesenchymal transition process.

Role of Glycans on Key Cell Surface Receptors That Regulate Cell Proliferation and Cell Death

Cells undergo proliferation and apoptosis, migration and differentiation via a number of cell surface receptors, most of which are heavily glycosylated. This review discusses receptor glycosylation and the known roles of glycans on the functions of receptors expressed in diverse cell types. We included growth factor receptors that have an intracellular tyrosine kinase domain, growth factor receptors that have a serine/threonine kinase domain, and cell-death-inducing receptors. N- and O-glycans have a wide range of functions including roles in receptor conformation, ligand binding, oligomerization, and activation of signaling cascades. A better understanding of these functions will enable control of cell survival and cell death in diseases such as cancer and in immune responses.