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Results: 7

1.
Figure 1

Figure 1. Tumor Cells with Coexistent RAS or RAF Mutations Are Resistant to AKT Inhibition. From: 4E-BP1 Is A Key Effector of the Oncogenic Activation of the AKT and ERK Signaling Pathways That Integrates Their Function in Tumors.

(A) Cell growth was assessed by using the CellTiter-Glo luminescent cell viability assay after 3 days of treatment with AKTi (0–10 µM). The results are expressed as half-maximal growth inhibitory concentration (IC50) of AKTi.
(B) Cells were treated with 1 µM AKTi, and the cell lysates were immunoblotted with the indicated antibodies. See also Figure S1.

Qing-Bai She, et al. Cancer Cell. ;18(1):39-51.
2.
Figure 7

Figure 7. Activated 4E-BP1 Represses PI3KCA and KRAS Mutant Tumor Growth. From: 4E-BP1 Is A Key Effector of the Oncogenic Activation of the AKT and ERK Signaling Pathways That Integrates Their Function in Tumors.

(A) HCT116 cells expressing vector, HA-4E-BP1 wt or HA-4E-BP1 (4Ala) were immunoblotted with the indicated antibodies or precipitated with m7GTP sepharose beads followed by immunoblotting of HA, 4E-BP1 and eIF4E.
(B) HCT116 cells expressing vector, HA-4E-BP1 wt or HA-4E-BP1 (4Ala) were transplanted into the right flank of nude mice. Tumor volume was measured twice each week with the results presented as mean tumor volume ± SEM of 5 mice in each group.
(C) Representative tumors expressing vector, HA-4E-BP1 wt or HA-4E-BP1 (4Ala), and immunoblot analysis of the tumor lysates using indicated antibodies.

Qing-Bai She, et al. Cancer Cell. ;18(1):39-51.
3.
Figure 6

Figure 6. Combined Inhibition of AKT and MEK Is Required to Dephosphorylate 4E-BP1 and Suppress Tumor Growth in Vivo. From: 4E-BP1 Is A Key Effector of the Oncogenic Activation of the AKT and ERK Signaling Pathways That Integrates Their Function in Tumors.

(A) Mice bearing established HCT116 xenografts were treated with PD0325901 (5 mg/kg), AKTi (100 mg/kg), combination of both drugs, or vehicle control once daily. Tumors were excised at various times after the fourth dose of drug administration. Tumor lysates were immunoblotted with the indicated antibodies.
(B–E) Mice bearing HCT116 (B), T84 (C), DLD-1 (D) and HCT15 (E) xenografts were treated with PD0325901 (5 mg/kg), AKTi (100 mg/kg), combination of both drugs, or vehicle control once daily for 5 consecutive days each week. The results are presented as the mean tumor volume ± SEM (n=5 mice/group) from two independent experiments. See also Figure S5.

Qing-Bai She, et al. Cancer Cell. ;18(1):39-51.
4.
Figure 5

Figure 5. 4E-BP1 Mediates the Effects of AKT and MEK Activation on Cap-Dependent Translation and Survival. From: 4E-BP1 Is A Key Effector of the Oncogenic Activation of the AKT and ERK Signaling Pathways That Integrates Their Function in Tumors.

(A) HCT116 cells were treated with 50 nM PD0325901 and 1 µM AKTi, alone or in combination for 6 h. Cell lysates were precipitated with m7GTP sepharose beads followed by immunoblotting with the indicated antibodies.
(B) siRNAs against the indicated genes or control siRNAs were transfected into HCT116 cells and incubated for 72 h. Cell lysates were immunoblotted with the indicated antibodies.
(C) siRNAs against the indicated genes or control siRNAs were transfected into HCT116 cells and incubated for 30 h. The cells were then transfected with a bicistronic luciferase reporter plasmid for 24 h, and then treated with 50 nM PD0325901 and 1 µM AKTi, alone or in combination for an additional 12 h. The inhibition of cap-dependent translation was determined as in Figure 3C. Values represent means ± SEM (n=3).
(D) Detection of eIF4E and β-actin by immunoblot in HCT116 cells expressing the indicated transgenes.
(E) HCT116 cells expressing eIF4E or control vector were transfected with a bicistronic luciferase reporter plasmid for 24 h, and then treated with 50 nM PD0325901 and 1 µM AKTi, alone or in combination for an additional 12 h. The inhibition of cap-dependent translation was determined as in Figure 3C. Values represent means ± SEM (n=3).
(F) siRNAs against 4E-BP1 or control siRNAs were transfected into HCT116 cells and incubated for 48 h. The cells were then treated with 50 nM PD0325901 and 1 µM AKTi, alone or in combination for the indicated additional times. Apoptosis was assessed by sub-G1 fraction of the cells. The results are expressed as the increased levels of apoptosis by subtracting each of the DMSO-treated controls and presented as means ± SEM (n=3).

Qing-Bai She, et al. Cancer Cell. ;18(1):39-51.
5.
Figure 4

Figure 4. Deletion of Mutant KRAS or PIK3CA Confers Dependence on the Other Pathway in Tumors in Which These Mutations Coexist. From: 4E-BP1 Is A Key Effector of the Oncogenic Activation of the AKT and ERK Signaling Pathways That Integrates Their Function in Tumors.

(A) The growth of isogenic HCT116 and DLD-1 cell lines in which the mutant allele of KRAS was deleted by homologous recombination were assessed after 3 days culture in the presence of AKTi. The results are expressed as IC50 of AKTi. Values represent means ± SEM (n=3).
(B and D) Cells were treated with 50 nM PD0325901 and 1 µM AKTi, alone or in combination for 6 h. Cell lysates were immunoblotted with the indicated antibodies or precipitated with m7GTP sepharose beads followed by immunoblotting of 4E-BP1 and eIF4E.
(C) Cells were transfected with a bicistronic luciferase reporter plasmid and then treated with 50 nM PD0325901 and 1 µM AKTi, alone or in combination. The inhibition of cap-dependent translation was determined as in Figure 3C. Values represent means ± SEM (n=3).
(E) The growth of HCT116 and DLD-1 isogenic cell lines in which the mutant allele of PIK3CA was deleted by homologous recombination were assessed after 3 days culture in the presence of PD0325901. The results are expressed as IC50 of PD0325901. Values represent means ± SEM (n=3).
(F) Cells were treated with DMSO or the indicated concentration of PD0325901 for 72 h. Apoptosis was assessed by sub-G1 fraction of the cells. Values represent means ± SEM (n=2). See also Figure S4.

Qing-Bai She, et al. Cancer Cell. ;18(1):39-51.
6.
Figure 2

Figure 2. Tumor Cells with Coexistent PIK3CA and KRAS Mutations Are Sensitive to Combined Inhibition of AKT and KRAS/MEK/ERK Signaling. From: 4E-BP1 Is A Key Effector of the Oncogenic Activation of the AKT and ERK Signaling Pathways That Integrates Their Function in Tumors.

(A) The growth of HCT116 cells was assessed after 3 days of treatment with PD0325901 (PD901) alone or in combination with AKTi. The results are expressed as the cell numbers relative to those with the DMSO-treated controls. Values represent means ± SEM (n=3).
(B) The growth of HCT116 cells were analyzed after 3 days of treatment with the drug combinations. Combination index (CI) values were determined by using the method of (Chou and Talalay, 1984) (CompuSyn software) for drug combinations with a fractional effect between 0.2 and 0.9 (20–90% of cell growth inhibition relative to control). CI values < 1 indicate drug synergy.
(C) HCT116 cells were treated with AKTi or DMSO with or without PD0325901 for 72 h. Apoptosis was assessed by sub-G1 fraction of the cells. Values represent means ± SEM (n=3).
(D) siRNAs against KRAS, control non-targeting siRNAs or transfection reagents (Mock) were transfected into HCT116 cells and incubated for 48 h and 72 h. Cell lysates were immunoblotted with the indicated antibodies.
(E) siRNAs against KRAS or control siRNAs were transfected into HCT116 cells and incubated for 48 h. The cells were then treated with 50 nM PD0325901 and 1 µM AKTi, alone or in combination or DMSO for the indicated additional times. Apoptosis was assessed by sub-G1 fraction of the cells. Values represent means ± SEM (n=3). See also Figure S2.

Qing-Bai She, et al. Cancer Cell. ;18(1):39-51.
7.
Figure 3

Figure 3. Combined Inhibition of AKT and MEK Is Required for Effective Inhibition of Cap-Dependent Translation in Tumor Cells with Coexistent PIK3CA and KRAS Mutations. From: 4E-BP1 Is A Key Effector of the Oncogenic Activation of the AKT and ERK Signaling Pathways That Integrates Their Function in Tumors.

(A, B, D and E) T47D (A and B) and HCT116 (D and E) cells were treated with 50 nM PD0325901 and 1 µM AKTi, alone or in combination for 6 h (A and B) or the indicated times (D and E). Cell lysates were immunoblotted with the indicated antibodies (A and D) or precipitated with m7GTP sepharose beads followed by immunoblotting of 4E-BP1 and eIF4E (B and E).
(C and F) T47D (C) and HCT116 (F) cells were transfected with a bicistronic luciferase reporter plasmid that detects cap-dependent translation of the Renilla luciferase gene and cap-independent Polio IRES-mediated translation of the firefly luciferase gene. The transfected cells were treated with 50 nM PD0325901 and 1 µM AKTi, alone or in combination. Luciferase activities were measured by a dual-luciferase assay, and the Renilla/firefly luciferase luminescence ratio was calculated for cap-dependent translational activity. The results are expressed as the inhibition of cap-dependent translation relative to the DMSO-treated controls at each time and presented as means ± SEM (n=3).
(G and H) HCT116 cells were treated with 50 nM PD0325901 and 1 µM AKTi, alone or in combination or DMSO for 12 h (G) or the indicated times (H). The cell lysates were separated on sucrose gradients (10–50%) and fractionated to visualize the indicated ribosomal species. The absorbance of translated polysomes (P) and untranslated monosomes (M) was continuously monitored at 254 nm, and the vertical dashed line separates the polysomal and monosomal fractions. The P/M ratio, an index of translational efficiency, was calculated by comparing areas under the polysome and monosome peaks using NIH image J. The results are expressed as a percentage of the P/M ratio relative to the DMSO-treated controls at each time and presented as means ± SEM (n=2) (H).
(I) 35S-methionine incorporation into protein was determined for HCT116 cells that were treated with 50 nM PD0325901 and 1 µM AKTi, alone or in combination or DMSO for 12 h. The results are expressed as a percentage of 35S-methionine incorporation/µg protein relative to the DMSO-treated controls and presented as means ± SEM (n=2). See also Figure S3.

Qing-Bai She, et al. Cancer Cell. ;18(1):39-51.

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