PAG1 directs SRC-family kinase intracellular localization to mediate receptor tyrosine kinase-induced differentiation

The role of phosphoprotein associated with glycosphingolipid-enriched microdomains 1 (PAG1) in regulating the progression of oral squamous cell carcinoma

OBJECTIVE

The aim of this study was to explore the role of the tumor suppressor phosphoprotein associated with glycosphingolipid-enriched microdomains 1 (PAG1) on oral squamous cell carcinoma (OSCC) and its molecular mechanism.

DESIGN

Immunohistochemistry detected the expression of PAG1 in normal and tumor tissues. The PAG1 overexpressed OSCC cell lines were constructed by lentivirus transfection. Cell Counting Kit-8 assay (CCK-8), clone formation and flow cytometry evaluated the impact of PAG1 on the proliferation and apoptosis of OSCC cells. RNA sequencing (RNA-seq) detected the changes in intracellular genes, and transmission electron microscope (TEM) was used to compare the number of autophagosomes in OSCC cells between Negative and PAG1 group. Quantitative reverse transcription-polymerase chain reaction (RT-qPCR) and Western blot were used to determine the expression of signaling pathway-related mRNA and proteins respectively.

RESULTS

In contrast to the normal tissues, PAG1 expression was significantly downregulated in tumor tissues. Treatment with lentivirus transfection, the expression of PAG1 in the OSCC cell lines was increase. Notably, transfected with PAG1-overexpressing lentivirus cells inhibited the proliferation of OSCC cells and promoted OSCC cells apoptosis. RNA-seq revealed that PAG1 mainly modulated the mitophagy and autophagy pathway, and many autophagosomes were observed in the PAG1 group using TEM. Mechanistically, we found that PAG1 upregulated the expression of autophagy related factors through inhibiting PI3K/Akt/mTOR signal pathway activation.

CONCLUSION

Overexpression of PAG1 inhibited OSCC progression by activating autophagy, its mechanism might be related to inhibition of PI3K/Akt/mTOR signal pathway phosphorylation.

Network models of protein phosphorylation, acetylation, and ubiquitination connect metabolic and cell signaling pathways in lung cancer

We analyzed large-scale post-translational modification (PTM) data to outline cell signaling pathways affected by tyrosine kinase inhibitors (TKIs) in ten lung cancer cell lines. Tyrosine phosphorylated, lysine ubiquitinated, and lysine acetylated proteins were concomitantly identified using sequential enrichment of post translational modification (SEPTM) proteomics. Machine learning was used to identify PTM clusters that represent functional modules that respond to TKIs. To model lung cancer signaling at the protein level, PTM clusters were used to create a co-cluster correlation network (CCCN) and select protein-protein interactions (PPIs) from a large network of curated PPIs to create a cluster-filtered network (CFN). Next, we constructed a Pathway Crosstalk Network (PCN) by connecting pathways from NCATS BioPlanet whose member proteins have PTMs that co-cluster. Interrogating the CCCN, CFN, and PCN individually and in combination yields insights into the response of lung cancer cells to TKIs. We highlight examples where cell signaling pathways involving EGFR and ALK exhibit crosstalk with BioPlanet pathways: Transmembrane transport of small molecules; and Glycolysis and gluconeogenesis. These data identify known and previously unappreciated connections between receptor tyrosine kinase (RTK) signal transduction and oncogenic metabolic reprogramming in lung cancer. Comparison to a CFN generated from a previous multi-PTM analysis of lung cancer cell lines reveals a common core of PPIs involving heat shock/chaperone proteins, metabolic enzymes, cytoskeletal components, and RNA-binding proteins. Elucidation of points of crosstalk among signaling pathways employing different PTMs reveals new potential drug targets and candidates for synergistic attack through combination drug therapy.

Single cell sequencing analysis constructed the N7-methylguanosine (m7G)-related prognostic signature in uveal melanoma

BACKGROUND

Uveal melanoma is a highly malignant tumor in the eye. Its recurrence and metastasis are common, and the prognosis is poor.

METHODS

The transcriptome data of UVM were downloaded from TCGA database, and the single cell sequencing dataset GSE139829 was downloaded from GEO database. Weighted co-expression network analysis was used to explore the modules associated with m7G. Lasso regression was used to construct M⁷G-related prognostic signature. Immune infiltration analysis was used to explore the significance of the model in the tumor immune microenvironment. Finally, cell assays were used to explore the function of key genes in the MUM-2B and OCM-1 cell lines of UVM.

RESULTS

The prognostic signature was constructed by Cox regression and Lasso regression. Patients could be divided into high-risk group and low-risk group by this signature, and the high-risk group had worse prognosis (P<0.05). Cell experiments showed that the proliferation, invasion and migration ability of UVM cell lines were significantly decreased after the knockdown of PAG1, a key gene in signature, which proved that PAG1 might be a potential target of UVM.

CONCLUSIONS

Our study explored the significance of m⁷G in UVM, provided biomarkers for its diagnosis and treatment.

Combination Approaches to Target PD-1 Signaling in Cancer

Cancer remains the second leading cause of death in the US, accounting for 25% of all deaths nationwide. Immunotherapy techniques bolster the immune cells' ability to target malignant cancer cells and have brought immense improvements in the field of cancer treatments. One important inhibitory protein in T cells, programmed cell death protein 1 (PD-1), has become an invaluable target for cancer immunotherapy. While anti-PD-1 antibody therapy is extremely successful in some patients, in others it fails or even causes further complications, including cancer hyper-progression and immune-related adverse events. Along with countless translational studies of the PD-1 signaling pathway, there are currently close to 5,000 clinical trials for antibodies against PD-1 and its ligand, PD-L1, around 80% of which investigate combinations with other therapies. Nevertheless, more work is needed to better understand the PD-1 signaling pathway and to facilitate new and improved evidence-based combination strategies. In this work, we consolidate recent discoveries of PD-1 signaling mediators and their therapeutic potential in combination with anti-PD-1/PD-L1 agents. We focus on the phosphatases SHP2 and PTPN2; the kinases ITK, VRK2, GSK-3, and CDK4/6; and the signaling adaptor protein PAG. We discuss their biology both in cancer cells and T cells, with a focus on their role in relation to PD-1 to determine their potential in therapeutic combinations. The literature discussed here was obtained from a search of the published literature and ClinicalTrials.gov with the following key terms: checkpoint inhibition, cancer immunotherapy, PD-1, PD-L1, SHP2, PTPN2, ITK, VRK2, CDK4/6, GSK-3, and PAG. Together, we find that all of these proteins are logical and promising targets for combination therapy, and that with a deeper mechanistic understanding they have potential to improve the response rate and decrease adverse events when thoughtfully used in combination with checkpoint inhibitors.

Systematic review of the receptor tyrosine kinase superfamily in neuroblastoma pathophysiology

BACKGROUND

Neuroblastoma is a devastating disease accounting for 15% of all childhood cancer deaths. Yet, our understanding of key molecular drivers such as receptor tyrosine kinases (RTKs) in this pathology remains poorly clarified. Here, we provide a systematic analysis of the RTK superfamily in the context of neuroblastoma pathogenesis.

METHODS

Statistical correlations for all RTK family members' expression to neuroblastoma patient survival across 10 independent patient cohorts were annotated, synthesized, and ranked using the R2: Genomics Analysis and Visualization Platform. Gene expression of selected members across different cancer cell lines was further analyzed in the Cancer Cell Line Encyclopedia, part of the Cancer Dependency Map portal (depmap portal ( http://depmap.org )). Finally, we provide a detailed literature review for highly ranked candidates.

RESULTS

Our analysis defined two subsets of RTKs showing robust associations with either better or worse survival, constituting potential novel players in neuroblastoma pathophysiology, diagnosis, and therapy. We review the available literature regarding the oncogenic functions of these RTKs, their roles in neuroblastoma pathophysiology, and potential utility as therapeutic targets.

CONCLUSIONS

Our systematic analysis and review of the RTK superfamily in neuroblastoma pathogenesis provides a new resource to guide the research community towards focused efforts investigating signaling pathways that contribute to neuroblastoma tumor establishment, growth, and/or aggressiveness and targeting these druggable molecules in novel therapeutic strategies.

Src-family Protein Tyrosine Kinases: A promising target for treating Cardiovascular Diseases

The Src-family protein tyrosine kinases (SFKs), a subfamily of non-receptor tyrosine kinases, are ubiquitously expressed in various cell types. Numerous studies have suggested that SFKs are related to signal transduction in major cardiac physiological and pathological processes, it is the activity of SFKs that is connected with the maintenance of cardiovascular homeostasis. Upon stimulation of various injury factors or stress, the phosphorylation state of SFKs is changed, which has been found to modulate different cardiac pathological conditions, such as hypertension, coronary heart disease, ischemic heart disease, myocardial ischemia-reperfusion injury, arrhythmia and cardiomyopathy via regulating cell growth, differentiation, movement and function, electrophysiologic signals. This review summarizes the basic information about SFKs, updates its role in the different processes underlying the development of multiple cardiovascular diseases (CVDs), and highlights their potential role as disease biomarkers and therapeutic targets, which would help understand the pathophysiology of CVDs and promote the further potential clinical adhibition.