Overexpression of PTPN21 promotes proliferation of EGF-stimulated acute lymphoblastic leukemia cells via the MAPK signaling pathways.

OBJECTIVES: This study aims to investigate the role of excessive Protein Tyrosine Phosphatase Non-Receptor Type 21 (PTPN21) in the proliferation of Acute Lymphoblastic Leukemia (ALL) cells with EGF stimulation. METHODS: PTPN21 was overexpressed in ALL cell lines by lentiviral transfection. Apoptosis was assayed by Annexin V/7-AAD staining. The proliferation and cell cycle of EGF-treated ALL cells were assessed by MTT and Ki-67/7-AAD staining respectively. The phosphorylation of Src tyrosine kinase and mediators of distinct MAPK pathways were assessed by Western blot. RESULTS: Overexpression of PTPN21 had minimal effect on the apoptosis of ALL cells, but significantly promoted the proliferation and cell cycle progression of ALL cells stimulated with EGF. The activity of Src tyrosine kinase and the MAPK pathways was elevated. Inhibition of MAPK pathways by specific inhibitors mitigated this pro-proliferative effect of excessive PTPN21 on EGF-stimulated ALL cells. CONCLUSION: PTPN21 may facilitate ALL progression by promoting cell proliferation via the Src/MAPK signaling pathways.

Essential genes analysis reveals small ribosomal subunit protein eS28 may be a prognostic factor and potential vulnerability in osteosarcoma.

Background: Osteosarcoma, the most common primary malignant bone tumor, is currently treated with surgery combined with chemotherapy, but the limited availability of targeted drugs contributes to a poor prognosis. Identifying effective therapeutic targets is crucial for improving the prognosis of osteosarcoma patients. Methods: We screened the DepMap database to identify essential genes as potential therapeutic targets for osteosarcoma. Gene Set Enrichment Analysis (GSEA) was employed to elucidate the biological roles of these essential genes. Promising candidates were filtered through univariate and multivariate Cox analyses, as well as Kaplan-Meier survival analyses using the GSE21257-OSA and TARGET-OSA datasets. The functional role of the target gene was assessed through cell experiments. Additionally, an in situ nude mice model was established to observe the gene's function, and RNA sequencing was utilized to explore the underlying molecular mechanism. Results: A total of 934 essential genes were identified based on their effects (Chronos) using the DepMap database. These genes were primarily enriched in the ribosome pathway according to GSEA analysis. Among them, 195 genes were associated with the ribosome pathway. Rps28, Rps7, and Rps25 were validated as promising candidates following univariate and multivariate Cox analyses of the TARGET-OSA and GSE21257-OSA datasets. Kaplan-Meier survival analyses indicated Rps28 represented an especially promising target, with high expression correlating with poor prognosis. Knockdown of small ribosomal subunit protein eS28, the protein of Rps28, inhibited proliferation, migration, and invasion in both in vitro and in vivo experiments. Silencing RPS28 affected the MAPK signaling pathway in osteosarcoma. Conclusion: In summary, Rps28 has been identified as an essential gene for osteosarcoma cell survival and eS28 may serve as a potential vulnerability in osteosarcoma.

Prognostic value and biological function of LRRN4 in colorectal cancer.

BACKGROUND: Several nervous and nerve-related biomarkers have been detected in colorectal cancer (CRC) and can contribute to the progression of CRC. However, the role of leucine-rich repeat neuronal 4 (LRRN4), a recently identified neurogenic marker, in CRC remains unclear. METHODS: We examined the expression and clinical outcomes of LRRN4 in CRC from TCGA-COREAD mRNA-sequencing datasets and immunohistochemistry in a Chinese cohort. Furthermore, colony formation, flow cytometry, wound healing assays and mouse xenograft models were used to investigate the biological significance of LRRN4 in CRC cell lines with LRRN4 knockdown or overexpression in vitro and in vivo. In addition, weighted coexpression network analysis, DAVID and western blot analysis were used to explore the potential molecular mechanism. RESULTS: We provide the first evidence that LRRN4 expression, at both the mRNA and protein levels, was remarkably high in CRC compared to controls and positively correlated with the clinical outcome of CRC patients. Specifically, LRRN4 was an independent prognostic factor for progression-free survival and overall survival in CRC patients. Further functional experiments showed that LRRN4 promoted cell proliferation, cell DNA synthesis and cell migration and inhibited apoptosis. Knockdown of LRRN4 can correspondingly decrease these effects in vitro and can significantly suppress the growth of xenografts. Several biological functions and signaling pathways were regulated by LRRN4, including proteoglycans in cancer, glutamatergic synapse, Ras, MAPK and PI3K. LRRN4 knockdown resulted in downregulation of Akt, p-Akt, ERK1/2 and p-ERK1/2, the downstream of the Ras/MAPK signaling pathway, overexpression of LRRN4 leaded to the upregulation of these proteins. CONCLUSIONS: Our results suggest that LRRN4 could be a biological and molecular determinant to stratify CRC patients into distinct risk categories, and mechanistically, this is likely attributable to LRRN4 regulating several malignant phenotypes of neoplastic cells via RAS/MAPK signal pathways.