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PD-L1 promotes OCT4 and Nanog expression in breast cancer stem cells by sustaining PI3K/AKT pathway activation.

ABSTRACT: The expression of PD-L1 in breast cancer is associated with estrogen receptor negativity, chemoresistance and epithelial-to-mesenchymal transition (EMT), all of which are common features of a highly tumorigenic subpopulation of cancer cells termed cancer stem cells (CSCs). Hitherto, the expression and intrinsic role of PD-L1 in the dynamics of breast CSCs has not been investigated. To address this issue, we used transcriptomic datasets, proteomics and several in vitro and in vivo assays. Expression profiling of a large breast cancer dataset (530 patients) showed statistically significant correlation (p?

SUBMITTER: Almozyan S

PROVIDER: S-EPMC5575465 | biostudies-other | 2017 Oct

REPOSITORIES: biostudies-other

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PD-L1 promotes OCT4 and Nanog expression in breast cancer stem cells by sustaining PI3K/AKT pathway activation.

Almozyan Sheema S Colak Dilek D Mansour Fatmah F Alaiya Ayodele A Al-Harazi Olfat O Qattan Amal A Al-Mohanna Falah F Al-Alwan Monther M Ghebeh Hazem H

International journal of cancer 20170630 7

The expression of PD-L1 in breast cancer is associated with estrogen receptor negativity, chemoresistance and epithelial-to-mesenchymal transition (EMT), all of which are common features of a highly tumorigenic subpopulation of cancer cells termed cancer stem cells (CSCs). Hitherto, the expression and intrinsic role of PD-L1 in the dynamics of breast CSCs has not been investigated. To address this issue, we used transcriptomic datasets, proteomics and several in vitro and in vivo assays. Express ...[more]

PMID: 28614911

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Project description:As immune checkpoint inhibitors (ICIs) continue to advance, more evidence has emerged that anti-PD-1/PD-L1 immunotherapy is an effective treatment against cancers. Known as the programmed death ligand-1 (PD-L1), this co-inhibitory ligand contributes to T cell exhaustion by interacting with programmed death-1 (PD-1) receptor. However, cancer-intrinsic signaling pathways of the PD-L1 molecule are not well elucidated. Therefore, the present study aimed to evaluate the regulatory network of PD-L1 and lay the basis of successful use of anti-PD-L1 immunotherapy in acute myeloid leukemia (AML). Data for AML patients were extracted from TCGA and GTEx databases. The downstream signaling pathways of PD-L1 were identified via Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis. The key PD-L1 related genes were selected by weighted gene co-expression network analysis (WGCNA), MCC algorithm and Molecular Complex Detection (MCODE). The CCK-8 assay was used to assess cell proliferation. Flow cytometry was used to determine cell apoptosis and cell cycle. Western blotting was used to identify the expression of the PI3K-AKT signaling pathway. PD-L1 was shown to be elevated in AML patients when compared with the control group, and high PD-L1 expression was associated with poor overall survival rate. The ECM-receptor interaction, as well as the PI3K-AKT signaling pathway, were important PD-L1 downstream pathways. All three analyses found eight genes (ITGA2B, ITGB3, COL6A5, COL6A6, PF4, NMU, AGTR1, F2RL3) to be significantly associated with PD-L1. Knockdown of PD-L1 inhibited AML cell proliferation, induced cell apoptosis and G2/M cell cycle arrest. Importantly, PD-L1 knockdown reduced the expression of PI3K and p-AKT, but PD-L1 overexpression increased their expression. The current study elucidates the main regulatory network and downstream targets of PD-L1 in AML, assisting in the understanding of the underlying mechanism of anti-PD-1/PD-L1 immunotherapy and paving the way for clinical application of ICIs in AML.

Project description:Methylenetetrahydrofolate dehydrogenase 2 (MTHFD2) has been implicated in the etiology of various human malignant tumors; however, its exact role in bladder cancer (BC) remains to be explored. Through reverse transcription‑quantitative PCR, western blotting and immunohistochemistry detection of BC tissue, combined with The Cancer Genome Atlas (TCGA) database analysis, the present study demonstrated that MTHFD2 was upregulated in BC tissues. MTHFD2 expression in patients with BC was frequently associated with worse prognosis, tumor immune cell infiltration and programmed death‑ligand 1 (PD‑L1) expression. Subsequently, using short hairpin RNA, the expression levels of MTHFD2 were knocked down in BC cell lines, and the results revealed that the tumor cell proliferation and colony formation abilities of cells were greatly reduced, as determined by Cell Counting Kit 8 and colony formation assays, as was the expression of PD‑L1, as determined by western blotting. These findings were also confirmed in a xenograft nude mouse model. Simultaneously, it was revealed that abnormal expression of MTHFD2 was closely associated with the PI3K/AKT signaling pathway in both RNA‑sequencing and TCGA datasets. This observation was verified in vitro by detecting the protein expression levels of PI3K and AKT by western blotting. The activation of PI3K and AKT was enhanced in BC cells (T24) following stimulation with 740Y‑P, a PI3K activator, and cellular activities and PD‑L1 expression levels were restored. Finally, it was demonstrated that the MTHFD2 levels were correlated with chemosensitivity to traditional BC chemotherapeutic agents and various PI3K/AKT‑targeted drugs, as determined by analyzing the Genomics of Drug Sensitivity in Cancer database. Overall, the present findings revealed that upregulation of MTHFD2 was associated with PD‑L1 activation in BC via the PI3K/AKT signaling pathway, suggesting that it could be a promising marker of chemotherapy and immunotherapy for BC.

Dataset Information

PD-L1 promotes OCT4 and Nanog expression in breast cancer stem cells by sustaining PI3K/AKT pathway activation.

Publications

PD-L1 promotes OCT4 and Nanog expression in breast cancer stem cells by sustaining PI3K/AKT pathway activation.

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