Limits...
Significance of KRAS/PAK1/Crk pathway in non-small cell lung cancer oncogenesis.

Mortazavi F, Lu J, Phan R, Lewis M, Trinidad K, Aljilani A, Pezeshkpour G, Tamanoi F - BMC Cancer (2015)

Bottom Line: Furthermore, KRAS mutant tumors expressed higher p-PAK1(Thr423) compared to KRAS wild type.KRAS prenylation inhibition by (FTI + GGTI) completely dephosphorylated proto-oncogene c-Crk on Serine 41 while Crk phosphorylation did not change by individual prenylation inhibitors or diluent.Combination of PAK1 inhibition and partial inhibition of all other KRAS effectors by (FTI + GGTI) dramatically altered morphology, motility and proliferation of H157 and A549 cells.

View Article: PubMed Central - PubMed

Affiliation: Division of Hematology/Oncology, West Los Angeles VA, Los Angeles, CA, USA. fredmortazavi@ucla.edu.

ABSTRACT

Background: Key effector(s) of mutated KRAS in lung cancer progression and metastasis are unknown. Here we investigated the role of PAK1/Crk axis in transduction of the oncogenic KRAS signal in non-small cell lung cancer (NSCLC).

Methods: We used NSCLC clinical specimens to examine the correlation among KRAS mutations (codon 12, 13 and 61); PAK1/Crk axis activation [p-PAK1(Thr423), p-Crk(Ser41)]; and adhesion molecules expression by immunohistochemistry. For assessing the role of proto-oncogene c-Crk as a KRAS effector, we inhibited KRAS in NSCLC cells by a combination of farnesyltransferase inhibitor (FTI) and geranylgeranyltransferase inhibitor (GGTI) and measured p-Crk-II(Ser41) by western blotting. Finally, we disrupted the signaling network downstream of KRAS by blocking KRAS/PAK1/Crk axis with PAK1 inhibitors (i.e., IPA-3, FRAX597 or FRAX1036) along with partial inhibition of all other KRAS effectors by prenylation inhibitors (FTI + GGTI) and examined the motility, morphology and proliferation of the NSCLC cells.

Results: Immunohistochemical analysis demonstrated an inverse correlation between PAK1/Crk phosphorylation and E-cadherin/p120-catenin expression. Furthermore, KRAS mutant tumors expressed higher p-PAK1(Thr423) compared to KRAS wild type. KRAS prenylation inhibition by (FTI + GGTI) completely dephosphorylated proto-oncogene c-Crk on Serine 41 while Crk phosphorylation did not change by individual prenylation inhibitors or diluent. Combination of PAK1 inhibition and partial inhibition of all other KRAS effectors by (FTI + GGTI) dramatically altered morphology, motility and proliferation of H157 and A549 cells.

Conclusions: Our data provide evidence that proto-oncogene c-Crk is operative downstream of KRAS in NSCLC. Previously we demonstrated that Crk receives oncogenic signals from PAK1. These data in conjunction with the work of others that have specified the role of PAK1 in transduction of KRAS signal bring forward the importance of KRAS/PAK1/Crk axis as a prominent pathway in the oncogenesis of KRAS mutant lung cancer.

No MeSH data available.


Related in: MedlinePlus

Cooperative disruption of signaling network downstream of mutated KRAS. Schematic view of KRAS/PAK1/Crk signaling pathway is demonstrated. Partial inhibition of KRAS signaling output by tolerable dose of prenylation inhibitors (i.e., FTI + GGTI) in addition to inhibition of a prominent KRAS effector (i.e., PAK1) result in dramatic anti-tumor effects. FTI: farnesyltransferase inhibitor, GGTI: geranylgeranyltransferase inhibitor, PAK1I: p21 associated kinase 1 inhibitor.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
getmorefigures.php?uid=PMC4477307&req=5

Fig10: Cooperative disruption of signaling network downstream of mutated KRAS. Schematic view of KRAS/PAK1/Crk signaling pathway is demonstrated. Partial inhibition of KRAS signaling output by tolerable dose of prenylation inhibitors (i.e., FTI + GGTI) in addition to inhibition of a prominent KRAS effector (i.e., PAK1) result in dramatic anti-tumor effects. FTI: farnesyltransferase inhibitor, GGTI: geranylgeranyltransferase inhibitor, PAK1I: p21 associated kinase 1 inhibitor.

Mentions: Considering inhibition of multiple downstream pathways might not be easily achievable, we reasoned that blockade of a prominent downstream pathway can be enhanced by addition of widespread partial blockade of KRAS signals. Therefore, we chose to utilize a PAK1 inhibitor [an inhibitor that blocks one of the prominent KRAS downstream pathways] and then add (FTI + GGTI) [which provide a partial signal blockade in all downstream KRAS effectors] for enhancing signal interruption of KRAS. As shown in Figures 7 and 9, this combination remarkably altered morphology, motility and proliferation of NSCLC cells. It appears that combination of prenylation inhibitors and PAK1 inhibitor adequately disrupt the signaling network downstream of KRAS (Figure 10) and provide a prominent anti-tumor effect. It is noteworthy that the observed synergy between prenylation inhibitors and a PAK1 inhibitor will provide the opportunity to use a low concentration of each inhibitor for blocking KRAS signals and thereby will enable us to avoid the risk of cellular toxicity.Figure 10


Significance of KRAS/PAK1/Crk pathway in non-small cell lung cancer oncogenesis.

Mortazavi F, Lu J, Phan R, Lewis M, Trinidad K, Aljilani A, Pezeshkpour G, Tamanoi F - BMC Cancer (2015)

Cooperative disruption of signaling network downstream of mutated KRAS. Schematic view of KRAS/PAK1/Crk signaling pathway is demonstrated. Partial inhibition of KRAS signaling output by tolerable dose of prenylation inhibitors (i.e., FTI + GGTI) in addition to inhibition of a prominent KRAS effector (i.e., PAK1) result in dramatic anti-tumor effects. FTI: farnesyltransferase inhibitor, GGTI: geranylgeranyltransferase inhibitor, PAK1I: p21 associated kinase 1 inhibitor.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4477307&req=5

Fig10: Cooperative disruption of signaling network downstream of mutated KRAS. Schematic view of KRAS/PAK1/Crk signaling pathway is demonstrated. Partial inhibition of KRAS signaling output by tolerable dose of prenylation inhibitors (i.e., FTI + GGTI) in addition to inhibition of a prominent KRAS effector (i.e., PAK1) result in dramatic anti-tumor effects. FTI: farnesyltransferase inhibitor, GGTI: geranylgeranyltransferase inhibitor, PAK1I: p21 associated kinase 1 inhibitor.
Mentions: Considering inhibition of multiple downstream pathways might not be easily achievable, we reasoned that blockade of a prominent downstream pathway can be enhanced by addition of widespread partial blockade of KRAS signals. Therefore, we chose to utilize a PAK1 inhibitor [an inhibitor that blocks one of the prominent KRAS downstream pathways] and then add (FTI + GGTI) [which provide a partial signal blockade in all downstream KRAS effectors] for enhancing signal interruption of KRAS. As shown in Figures 7 and 9, this combination remarkably altered morphology, motility and proliferation of NSCLC cells. It appears that combination of prenylation inhibitors and PAK1 inhibitor adequately disrupt the signaling network downstream of KRAS (Figure 10) and provide a prominent anti-tumor effect. It is noteworthy that the observed synergy between prenylation inhibitors and a PAK1 inhibitor will provide the opportunity to use a low concentration of each inhibitor for blocking KRAS signals and thereby will enable us to avoid the risk of cellular toxicity.Figure 10

Bottom Line: Furthermore, KRAS mutant tumors expressed higher p-PAK1(Thr423) compared to KRAS wild type.KRAS prenylation inhibition by (FTI + GGTI) completely dephosphorylated proto-oncogene c-Crk on Serine 41 while Crk phosphorylation did not change by individual prenylation inhibitors or diluent.Combination of PAK1 inhibition and partial inhibition of all other KRAS effectors by (FTI + GGTI) dramatically altered morphology, motility and proliferation of H157 and A549 cells.

View Article: PubMed Central - PubMed

Affiliation: Division of Hematology/Oncology, West Los Angeles VA, Los Angeles, CA, USA. fredmortazavi@ucla.edu.

ABSTRACT

Background: Key effector(s) of mutated KRAS in lung cancer progression and metastasis are unknown. Here we investigated the role of PAK1/Crk axis in transduction of the oncogenic KRAS signal in non-small cell lung cancer (NSCLC).

Methods: We used NSCLC clinical specimens to examine the correlation among KRAS mutations (codon 12, 13 and 61); PAK1/Crk axis activation [p-PAK1(Thr423), p-Crk(Ser41)]; and adhesion molecules expression by immunohistochemistry. For assessing the role of proto-oncogene c-Crk as a KRAS effector, we inhibited KRAS in NSCLC cells by a combination of farnesyltransferase inhibitor (FTI) and geranylgeranyltransferase inhibitor (GGTI) and measured p-Crk-II(Ser41) by western blotting. Finally, we disrupted the signaling network downstream of KRAS by blocking KRAS/PAK1/Crk axis with PAK1 inhibitors (i.e., IPA-3, FRAX597 or FRAX1036) along with partial inhibition of all other KRAS effectors by prenylation inhibitors (FTI + GGTI) and examined the motility, morphology and proliferation of the NSCLC cells.

Results: Immunohistochemical analysis demonstrated an inverse correlation between PAK1/Crk phosphorylation and E-cadherin/p120-catenin expression. Furthermore, KRAS mutant tumors expressed higher p-PAK1(Thr423) compared to KRAS wild type. KRAS prenylation inhibition by (FTI + GGTI) completely dephosphorylated proto-oncogene c-Crk on Serine 41 while Crk phosphorylation did not change by individual prenylation inhibitors or diluent. Combination of PAK1 inhibition and partial inhibition of all other KRAS effectors by (FTI + GGTI) dramatically altered morphology, motility and proliferation of H157 and A549 cells.

Conclusions: Our data provide evidence that proto-oncogene c-Crk is operative downstream of KRAS in NSCLC. Previously we demonstrated that Crk receives oncogenic signals from PAK1. These data in conjunction with the work of others that have specified the role of PAK1 in transduction of KRAS signal bring forward the importance of KRAS/PAK1/Crk axis as a prominent pathway in the oncogenesis of KRAS mutant lung cancer.

No MeSH data available.


Related in: MedlinePlus