Limits...
Combined targeting of BRAF and CRAF or BRAF and PI3K effector pathways is required for efficacy in NRAS mutant tumors.

Jaiswal BS, Janakiraman V, Kljavin NM, Eastham-Anderson J, Cupp JE, Liang Y, Davis DP, Hoeflich KP, Seshagiri S - PLoS ONE (2009)

Bottom Line: We find that in colon cancer cells harboring a KRAS(G13D) mutant allele, knocking down KRAS alone or the RAFs in combination or the RAF effectors, MEK1 and MEK2, together is effective in delaying tumor growth in vivo.In melanoma cells harboring an NRAS(Q61L) or NRAS(Q61K) mutant allele, we find that targeting NRAS alone or both BRAF and CRAF in combination or both BRAF and PIK3CA together showed efficacy.Our data indicates that targeting oncogenic NRAS-driven melanomas require decrease in both pERK and pAKT downstream of RAS-effectors for efficacy.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular Biology, Genentech Inc., South San Francisco, California, United States of America.

ABSTRACT

Background: Oncogenic RAS is a highly validated cancer target. Attempts at targeting RAS directly have so far not succeeded in the clinic. Understanding downstream RAS-effectors that mediate oncogenesis in a RAS mutant setting will help tailor treatments that use RAS-effector inhibitors either alone or in combination to target RAS-driven tumors.

Methodology/principal findings: In this study, we have investigated the sufficiency of targeting RAS-effectors, RAF, MEK and PI3-Kinase either alone or in combination in RAS mutant lines, using an inducible shRNA in vivo mouse model system. We find that in colon cancer cells harboring a KRAS(G13D) mutant allele, knocking down KRAS alone or the RAFs in combination or the RAF effectors, MEK1 and MEK2, together is effective in delaying tumor growth in vivo. In melanoma cells harboring an NRAS(Q61L) or NRAS(Q61K) mutant allele, we find that targeting NRAS alone or both BRAF and CRAF in combination or both BRAF and PIK3CA together showed efficacy.

Conclusion/significance: Our data indicates that targeting oncogenic NRAS-driven melanomas require decrease in both pERK and pAKT downstream of RAS-effectors for efficacy. This can be achieved by either targeting both BRAF and CRAF or BRAF and PIK3CA simultaneously in NRAS mutant tumor cells.

Show MeSH

Related in: MedlinePlus

Targeting RAS and its downstream effectors leads to delay in cell cycle progression.A representative image showing the effect on cell cycle progression following knock-down of RAS and its downstream effectors as indicated in HCT116 or IPC298 cells. The complete results of cell cycle analysis from triplicates of two independent experiments along with the standard error of the mean values are presented in Table 1.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC2683562&req=5

pone-0005717-g008: Targeting RAS and its downstream effectors leads to delay in cell cycle progression.A representative image showing the effect on cell cycle progression following knock-down of RAS and its downstream effectors as indicated in HCT116 or IPC298 cells. The complete results of cell cycle analysis from triplicates of two independent experiments along with the standard error of the mean values are presented in Table 1.

Mentions: To address the mechanism by which loss of RAS (KRAS in HCT116 and NRAS in IPC298) reduced cellular proliferation and delayed tumor growth, we analyzed cell cycle progression and apoptosis induction in these cells following dox treatment. Induction of NRAS shRNA expression in the NRAS mutant-IPC298 line led to ∼65% of the cells arresting in G1 compared to ∼47% of the cells in G1 in untreated cells. This led to a delayed entry into S and G2/M phase (Table 1 and Figure 8). In the KRAS mutant HCT116 cells, KRAS knock-down following KRAS shRNA induction, lead to the cells accumulating in S phase, thereby preventing G2/M progression (Table 1 and Figure 8).


Combined targeting of BRAF and CRAF or BRAF and PI3K effector pathways is required for efficacy in NRAS mutant tumors.

Jaiswal BS, Janakiraman V, Kljavin NM, Eastham-Anderson J, Cupp JE, Liang Y, Davis DP, Hoeflich KP, Seshagiri S - PLoS ONE (2009)

Targeting RAS and its downstream effectors leads to delay in cell cycle progression.A representative image showing the effect on cell cycle progression following knock-down of RAS and its downstream effectors as indicated in HCT116 or IPC298 cells. The complete results of cell cycle analysis from triplicates of two independent experiments along with the standard error of the mean values are presented in Table 1.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2683562&req=5

pone-0005717-g008: Targeting RAS and its downstream effectors leads to delay in cell cycle progression.A representative image showing the effect on cell cycle progression following knock-down of RAS and its downstream effectors as indicated in HCT116 or IPC298 cells. The complete results of cell cycle analysis from triplicates of two independent experiments along with the standard error of the mean values are presented in Table 1.
Mentions: To address the mechanism by which loss of RAS (KRAS in HCT116 and NRAS in IPC298) reduced cellular proliferation and delayed tumor growth, we analyzed cell cycle progression and apoptosis induction in these cells following dox treatment. Induction of NRAS shRNA expression in the NRAS mutant-IPC298 line led to ∼65% of the cells arresting in G1 compared to ∼47% of the cells in G1 in untreated cells. This led to a delayed entry into S and G2/M phase (Table 1 and Figure 8). In the KRAS mutant HCT116 cells, KRAS knock-down following KRAS shRNA induction, lead to the cells accumulating in S phase, thereby preventing G2/M progression (Table 1 and Figure 8).

Bottom Line: We find that in colon cancer cells harboring a KRAS(G13D) mutant allele, knocking down KRAS alone or the RAFs in combination or the RAF effectors, MEK1 and MEK2, together is effective in delaying tumor growth in vivo.In melanoma cells harboring an NRAS(Q61L) or NRAS(Q61K) mutant allele, we find that targeting NRAS alone or both BRAF and CRAF in combination or both BRAF and PIK3CA together showed efficacy.Our data indicates that targeting oncogenic NRAS-driven melanomas require decrease in both pERK and pAKT downstream of RAS-effectors for efficacy.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular Biology, Genentech Inc., South San Francisco, California, United States of America.

ABSTRACT

Background: Oncogenic RAS is a highly validated cancer target. Attempts at targeting RAS directly have so far not succeeded in the clinic. Understanding downstream RAS-effectors that mediate oncogenesis in a RAS mutant setting will help tailor treatments that use RAS-effector inhibitors either alone or in combination to target RAS-driven tumors.

Methodology/principal findings: In this study, we have investigated the sufficiency of targeting RAS-effectors, RAF, MEK and PI3-Kinase either alone or in combination in RAS mutant lines, using an inducible shRNA in vivo mouse model system. We find that in colon cancer cells harboring a KRAS(G13D) mutant allele, knocking down KRAS alone or the RAFs in combination or the RAF effectors, MEK1 and MEK2, together is effective in delaying tumor growth in vivo. In melanoma cells harboring an NRAS(Q61L) or NRAS(Q61K) mutant allele, we find that targeting NRAS alone or both BRAF and CRAF in combination or both BRAF and PIK3CA together showed efficacy.

Conclusion/significance: Our data indicates that targeting oncogenic NRAS-driven melanomas require decrease in both pERK and pAKT downstream of RAS-effectors for efficacy. This can be achieved by either targeting both BRAF and CRAF or BRAF and PIK3CA simultaneously in NRAS mutant tumor cells.

Show MeSH
Related in: MedlinePlus