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Simultaneous inhibition of pan-phosphatidylinositol-3-kinases and MEK as a potential therapeutic strategy in peripheral T-cell lymphomas.

ABSTRACT: Peripheral T-cell lymphomas are very aggressive hematologic malignancies for which there is no targeted therapy. New, rational approaches are necessary to improve the very poor outcome in these patients. Phosphatidylinositol-3-kinase is one of the most important pathways in cell survival and proliferation. We hypothesized that phosphatidylinositol-3-kinase inhibitors could be rationally selected drugs for treating peripheral T-cell lymphomas. Several phosphatidylinositol-3-kinase isoforms were inhibited genetically (using small interfering RNA) and pharmacologically (with CAL-101 and GDC-0941 compounds) in a panel of six peripheral and cutaneous T-cell lymphoma cell lines. Cell viability was measured by intracellular ATP content; apoptosis and cell cycle changes were checked by flow cytometry. Pharmacodynamic biomarkers were assessed by western blot. The PIK3CD gene, which encodes the ? isoform of phosphatidylinositol-3-kinase, was overexpressed in cell lines and primary samples, and correlated with survival pathways. However, neither genetic nor specific pharmacological inhibition of phosphatidylinositol-3-kinase ? affected cell survival. In contrast, the pan-phosphatidylinositol-3-kinase inhibitor GDC-0941 arrested all T-cell lymphoma cell lines in the G1 phase and induced apoptosis in a subset of them. We identified phospho-GSK3? and phospho-p70S6K as potential biomarkers of phosphatidylinositol-3-kinase inhibitors. Interestingly, an increase in ERK phosphorylation was observed in some GDC -0941-treated T-cell lymphoma cell lines, suggesting the presence of a combination of phosphatidylinositol-3-kinase and MEK inhibitors. A highly synergistic effect was found between the two inhibitors, with the combination enhancing cell cycle arrest at G0/G1 in all T-cell lymphoma cell lines, and reducing cell viability in primary tumor T cells ex vivo. These results suggest that the combined treatment of pan-phosphatidylinositol-3-kinase + MEK inhibitors could be more effective than single phosphatidylinositol-3-kinase inhibitor treatment, and therefore, that this combination could be of therapeutic value for treating peripheral and cutaneous T-cell lymphomas.

SUBMITTER: Martin-Sanchez E

PROVIDER: S-EPMC3533660 | biostudies-literature | 2013 Jan

REPOSITORIES: biostudies-literature

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Simultaneous inhibition of pan-phosphatidylinositol-3-kinases and MEK as a potential therapeutic strategy in peripheral T-cell lymphomas.

Martín-Sánchez Esperanza E Rodríguez-Pinilla Socorro M SM Sánchez-Beato Margarita M Lombardía Luis L Domínguez-González Beatriz B Romero Diana D Odqvist Lina L García-Sanz Pablo P Wozniak Magdalena B MB Kurz Guido G Blanco-Aparicio Carmen C Mollejo Manuela M Alves F Javier FJ Menárguez Javier J González-Palacios Fernando F Rodríguez-Peralto José Luis JL Ortiz-Romero Pablo L PL García Juan F JF Bischoff James R JR Piris Miguel A MA

Haematologica 20120716 1

Peripheral T-cell lymphomas are very aggressive hematologic malignancies for which there is no targeted therapy. New, rational approaches are necessary to improve the very poor outcome in these patients. Phosphatidylinositol-3-kinase is one of the most important pathways in cell survival and proliferation. We hypothesized that phosphatidylinositol-3-kinase inhibitors could be rationally selected drugs for treating peripheral T-cell lymphomas. Several phosphatidylinositol-3-kinase isoforms were i ...[more]

PMID: 22801959

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Project description:The reciprocal relationship between malignant T cells and lymphoma-associated macrophages (LAM) within the tumor microenvironment (TME) is unique, as LAMs are well poised to provide ligands for antigen, costimulatory, and cytokine receptors that promote T-cell lymphoma growth. Conversely, malignant T cells promote the functional polarization and homeostatic survival of LAM. Therefore, we sought to determine the extent to which LAMs are a therapeutic vulnerability in these lymphomas, and to identify effective therapeutic strategies for their depletion. We utilized complementary genetically engineered mouse models and primary peripheral T-cell lymphoma (PTCL) specimens to quantify LAM expansion and proliferation. A high-throughput screen was performed to identify targeted agents that effectively deplete LAM within the context of PTCL. We observed that LAMs are dominant constituents of the TME in PTCL. Furthermore, their dominance was explained, at least in part, by their proliferation and expansion in response to PTCL-derived cytokines. Importantly, LAMs are a true dependency in these lymphomas, as their depletion significantly impaired PTCL progression. These findings were extrapolated to a large cohort of human PTCL specimens where LAM proliferation was observed. A high-throughput screen demonstrated that PTCL-derived cytokines led to relative resistance to CSF1R selective inhibitors, and culminated in the identification of dual CSF1R/JAK inhibition as a novel therapeutic strategy to deplete LAM in these aggressive lymphomas. Malignant T cells promote the expansion and proliferation of LAM, which are a bone fide dependency in these lymphomas, and are effectively depleted with a dual CSF1R/JAK inhibitor.SignificanceLAMs are a therapeutic vulnerability, as their depletion impairs T-cell lymphoma disease progression. Pacritinib, a dual CSF1R/JAK inhibitor, effectively impaired LAM viability and expansion, prolonged survival in preclinical T-cell lymphoma models, and is currently being investigated as a novel therapeutic approach in these lymphomas.

Dataset Information

Simultaneous inhibition of pan-phosphatidylinositol-3-kinases and MEK as a potential therapeutic strategy in peripheral T-cell lymphomas.

Publications

Simultaneous inhibition of pan-phosphatidylinositol-3-kinases and MEK as a potential therapeutic strategy in peripheral T-cell lymphomas.

Similar Datasets

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