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Targeting the Phosphoinositide 3-Kinase p110? Isoform Impairs Cell Proliferation, Survival and Tumor Growth in Small Cell Lung Cancer

ABSTRACT: Purpose: The phosphoinositide 3-kinase (PI3K) pathway is fundamental for cell proliferation and survival and is frequently altered and activated in neoplasia, including carcinomas of the lung. In this study we investigated the potential of targeting the catalytic class IA PI3K isoforms in small cell lung cancer (SCLC), which is the most aggressive of all lung cancer types. Experimental Design: The expression of PI3K isoforms in patient specimens was analyzed. The effects on SCLC cell survival and downstream signaling were determined following PI3K isoform inhibition by selective inhibitors or down-regulation by small interfering RNA. Results: Over-expression of the PI3K isoforms p110 -alpha and p110-alpha was shown by immunohistochemistry in primary SCLC tissue samples. Targeting the PI3K p110 -alpha with RNA interference (RNAi) or selective pharmacological inhibitors resulted in strongly affected cell proliferation of SCLC cells in vitro and in vivo, while targeting p110-alph was less effective. Inhibition of p110 -alpha also resulted in increased apoptosis and autophagy, which was accompanied by decreased phosphorylation of Akt and components of the mammalian target of rapamycin (mTOR) pathway, such as the ribosomal S6 protein, and the eukaryotic translation initiation factor 4E-binding protein 1 (4E-BP1). A DNA microarray analysis revealed that p110-alpha inhibition profoundly affected the balance of pro- and anti-apoptotic Bcl-2 family proteins. Finally, p110 -alpha inhibition led to impaired SCLC tumor formation and vascularization in vivo. Conclusion: Together our data demonstrate the key involvement of the PI3K isoform p110 -alpha in multiple tumor-promoting processes in SCLC. 3 control samples, 3 samples for two treaments

ORGANISM(S): Homo sapiens

SUBMITTER: Rehrauer Hubert

PROVIDER: S-ECPF-GEOD-40564 | biostudies-other |

REPOSITORIES: biostudies-other

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Project description:Simple Summary Human glioblastoma is the most common and malignant primary brain tumor and is universally fatal. Currently, there is no cure for the disease. One major hurdle to developing effective therapies against GBM has been our lack of understanding of regulators of crucial processes and features that define and sustain tumor cells. This study reveals a novel role of transcription factor TCF12 in the regulation of proliferation in GBM tumors using human patient-derived cell lines and an in vivo mouse GBM model. We find that TCF12 deficiency impairs the proliferation of tumor cells in vitro and slows tumor growth in vivo resulting in improved overall survival. We also find that TCF12 regulates the expression of some key regulators of the cell cycle in tumor cells. Abstract Isocitrate dehydrogenase (IDH)-wild-type glioblastoma (GBM) is the most common and aggressive primary brain tumor which carries a very poor overall prognosis and is universally fatal. Understanding the transcriptional regulation of the proliferation of GBM tumor cells is critical for developing novel and effective treatments. In this study, we investigate the role of the transcription factor TCF12 in the regulation of GBM proliferation using human and murine GBM cell lines and an in vivo GBM xenograft model. Our study shows that TCF12 deficiency severely impairs proliferation of tumor cells in vitro by disrupting/blocking the G1 to S phase transition. We also discover that TCF12 loss significantly improves animal survival and that TCF12-deficient tumors grow much slower in vivo. Overexpression of TCF12, on the other hand, leads to an increase in the proliferation of tumor cells in vitro and more aggressive tumor progression in vivo. Interestingly, loss of TCF12 leads to upregulation of signature genes of the oligodendrocytic lineage in GBM stem cells, suggesting a role for TCF12 in inhibiting differentiation along the oligodendrocytic lineage. Transcriptomic data also reveals that loss of TCF12 leads to dysregulation of the expression of key genes in the cell cycle. Our work demonstrates critical roles of TCF12 in GBM tumor progression.

Project description:BackgroundImmunotherapy has emerged as a promising treatment strategy in malignant tumors. Inhibitors and neutralizing antibodies targeted PD-1 or PD-L1 show improved clinical outcomes in advanced non-small cell lung cancers (NSCLCs). Previous studies concluded that PD-1 was mainly expressed on activated T cells, B cells and other immune cells. Recently, two studies suggested that PD-1 could be detected in the tumor cells of melanoma and hepatocellular carcinoma. Tumor-endogenous PD-1 in NSCLCs has not been reported at present. Thus, we intended to explore the expression and prognostic relevance of tumor-endogenous PD-1 in NSCLCs.MethodsWe detected the PD-1 expression in fresh tumor samples and tumor slices by flow cytometer and immunohistochemical analysis respectively. Overall survival (OS) and dis-ease-free survival (DFS) were analyzed with Kaplan-Meier survival curve. We explored the PD-1 expression in lung cancer cell lines and investigated its effect on cell proliferation.ResultsFlow cytometry showed that tumor cells with endogenous PD-1 constituted 2.08%, 2.42%, 1.79%, and 1.21% in 4 clinical NSCLC samples respectively. Thirty-four patients (34%) in the cohort were positive for tumor-endogenous PD-1 in IHC analysis. Patients with tumor-endogenous PD-1 had significantly worse 5-year overall survival (OS) and disease-free survival (DFS). Multivariate analysis identified tumor-endogenous PD-1 as an independent risk factor (HR =3.807, 95% CI: 2.031-7.135, P<0.05). PD-1 could be observed in 4 kinds of lung cancer cell lines (A549, H1975, H1299 and HCC827). PD-1 overexpression could enhance proliferation and clone formation of these cell lines.ConclusionsPD-1 was endogenously expressed on the tumor cells of NSCLCs, and it could serve as an independent prognostic risk factor. The molecular mechanism of inferior survival of tumor-endogenous PD-1 may attribute to its role in promoting cell proliferation and clone formation. Our results demonstrated the non-immune role of PD-1 in tumor microenvironment and may provide new thinking for the therapy of NSCLCs.

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Targeting the Phosphoinositide 3-Kinase p110? Isoform Impairs Cell Proliferation, Survival and Tumor Growth in Small Cell Lung Cancer

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