American Society of Hematology

Figure 6.

$MTOR is a targetable vulnerability in ATLL, and the combination of palbociclib with mTORC1 inhibitors is synergistically toxic for ATLL cells. (A) Heatmap of gene essentialities identified in genome-wide CRISPR library screening. The genes were manually selected among genes in T-cell lymphoma-related molecular pathway. (B) Immunoblot analysis of MTOR proteins in sgMTOR-transduced ST1 cells. (C) The indicated cell lines were infected with a lentivirus expressing sgMTOR or control sgAAVS1 together with GFP. The GFP-positive cell fraction was monitored as in Figure 2A. (D) Immunoblot analysis of phosphorylated S6 and phosphorylated 4EBP1 proteins in sgTP53-transduced ST1 cells treated with palbociclib (1 μM) for 4 hours. (E) Upper panel: viable cells were measured by the MTS assay for the indicated ATLL cell lines treated with the indicated concentrations of palbociclib and everolimus for 4 days. Lower panel: a combination index is shown. Lower than 1.0 indicates a synergistic effect. (F) Upper panel: viable cells were measured by the MTS assay for sgTP53- or control sgAAVS1-transduced ST1 cells treated with the indicated concentrations of palbociclib and everolimus for 4 days. Lower panel: a combination index is shown. Lower than 1.0 indicates a synergistic effect. (G,H) Immunoblot analysis of phosphorylated Rb (G), phosphorylated S6 (H), and phosphorylated 4EBP1 proteins (H) in ST1 and KK1 cells treated with palbociclib (0.5 μM and 1.25 μM, respectively) and everolimus (2.5 μM) for 24 hours. Error bars represent the SEM of replicates (C,E-F).$

MTOR is a targetable vulnerability in ATLL, and the combination of palbociclib with mTORC1 inhibitors is synergistically toxic for ATLL cells. (A) Heatmap of gene essentialities identified in genome-wide CRISPR library screening. The genes were manually selected among genes in T-cell lymphoma-related molecular pathway. (B) Immunoblot analysis of MTOR proteins in sgMTOR-transduced ST1 cells. (C) The indicated cell lines were infected with a lentivirus expressing sgMTOR or control sgAAVS1 together with GFP. The GFP-positive cell fraction was monitored as in Figure 2A. (D) Immunoblot analysis of phosphorylated S6 and phosphorylated 4EBP1 proteins in sgTP53-transduced ST1 cells treated with palbociclib (1 μM) for 4 hours. (E) Upper panel: viable cells were measured by the MTS assay for the indicated ATLL cell lines treated with the indicated concentrations of palbociclib and everolimus for 4 days. Lower panel: a combination index is shown. Lower than 1.0 indicates a synergistic effect. (F) Upper panel: viable cells were measured by the MTS assay for sgTP53- or control sgAAVS1-transduced ST1 cells treated with the indicated concentrations of palbociclib and everolimus for 4 days. Lower panel: a combination index is shown. Lower than 1.0 indicates a synergistic effect. (G,H) Immunoblot analysis of phosphorylated Rb (G), phosphorylated S6 (H), and phosphorylated 4EBP1 proteins (H) in ST1 and KK1 cells treated with palbociclib (0.5 μM and 1.25 μM, respectively) and everolimus (2.5 μM) for 24 hours. Error bars represent the SEM of replicates (C,E-F).

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