Combination of bulk RNA sequencing and scRNA sequencing uncover the molecular characteristics of MAPK signaling in kidney renal clear cell carcinoma.

The MAPK signaling pathway significantly impacts cancer progression and resistance; however, its functions remain incompletely assessed across various cancers, particularly in kidney renal clear cell carcinoma (KIRC). Therefore, there is an urgent need for comprehensive pan-cancer investigations of MAPK signaling, particularly within the context of KIRC. In this research, we obtained TCGA pan-cancer multi-omics data and conducted a comprehensive analysis of the genomic and transcriptomic characteristics of the MAPK signaling pathway. For in-depth investigation in KIRC, status of MAPK pathway was quantitatively estimated by ssGSEA and Ward algorithm was utilized for cluster analysis. Molecular characteristics and clinical prognoses of KIRC patients with distinct MAPK activities were comprehensively explored using a series of bioinformatics algorithms. Subsequently, a combination of LASSO and COX regression analyses were utilized sequentially to construct a MAPK-related signature to help identify the risk level of each sample. Patients in the C1 subtype exhibited relatively higher levels of MAPK signaling activity, which were associated with abundant immune cell infiltration and favorable clinical outcomes. Single-cell RNA sequencing (scRNA-seq) analysis of KIRC samples identified seven distinct cell types, and endothelial cells in tumor tissues had obviously higher MAPK scores than normal tissues. The immunohistochemistry results indicated the reduced expression levels of PAPSS1, MAP3K11, and SPRED1 in KIRC samples. In conclusion, our study represents the first integration of bulk RNA sequencing and single-cell RNA sequencing to elucidate the molecular characteristics of MAPK signaling in KIRC, providing a solid foundation for precision oncology.

Brain-derived Neurotrophic Factor Promotes Growth of Neurons and Neural Stem Cells Possibly by Triggering the Phosphoinositide 3-Kinase/ AKT/Glycogen Synthase Kinase-3ß/ß-catenin Pathway.

BACKGROUND: Brain-derived neurotrophic factor (BDNF) plays a crucial role in promoting survival and differentiation of neurons and neural stem cells (NSCs), but the downstream regulating mechanisms remain poorly understood. OBJECTIVE: We investigated whether BDNF exerts its effect by triggering the phosphoinositide 3-kinase (PI3K), protein kinase B, PKB (AKT), glycogen synthase kinase-3ß (GSK-3ß) and ß-catenin signaling pathway in cultured neurons and NSCs derived from the rat embryonic spinal cord. METHOD: Immunocytochemistry was used to detect neuronal and NSCs characteristics. RT-PCR was used to detect PI3K/AKT/GSK3ß/ß-catenin pathway expression. RESULTS: Neurons and NSCs were successfully separated and cultured from Sprague-Dawley rat embryonic spinal cord and were respectively labeled using immunocytochemistry. Neuron-specific nuclear protein, neuronal class III ß-tubulin, and neurofilament expression were detected in neurons; nestin, glial fibrillary acidic protein, microtubule-associated protein 2 and chondroitin sulfate glycosaminoglycan expression were detected in the NSCs. BDNF promoted significant neuronal growth (number, soma size, and average neurite length), as well as NSCs proliferation and differentiation, but BDNF antibody decreased neuronal growth and NSCs proliferation and differentiation. RT-PCR was used to detect changes in BDNF signal pathway components, showing that BDNF upregulated tropomyosin receptor kinase B, phosphoinositide 3-kinase (PI3K), AKT and ß-catenin, but downregulated GSK-3ß in the neurons and NSCs. BDNF antibody downregulated BDNF, tropomyosin receptor kinase B, PI3K, AKT, ß-catenin and cellular-myelocytomatosis viral oncogene, but upregulated GSK- 3ß, in the neurons and NSCs. CONCLUSION: Our findings suggested that BDNF contributed to neuronal growth and proliferation and differentiation of NSCs in vitro by stimulating PI3K/AKT/GSK3ß/ß-catenin pathways.