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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

PAK1 activation is inversely correlated with E-cadherin and p120-catenin expression in NSCLC cells. A-Western blots demonstrating E-cadherin, p120-catenin, PAK1 and p-PAK1(Thr423) expression in a panel of NSCLC cells as well as immortalized normal human respiratory epithelial cells (BEAS-2B). B-Bar chart demonstrating signal intensity of p-PAK1/PAK1, p120-catenin and E-cadherin normalized to the value of BEAS-2B cells.
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Fig3: PAK1 activation is inversely correlated with E-cadherin and p120-catenin expression in NSCLC cells. A-Western blots demonstrating E-cadherin, p120-catenin, PAK1 and p-PAK1(Thr423) expression in a panel of NSCLC cells as well as immortalized normal human respiratory epithelial cells (BEAS-2B). B-Bar chart demonstrating signal intensity of p-PAK1/PAK1, p120-catenin and E-cadherin normalized to the value of BEAS-2B cells.

Mentions: Furthermore, we examined PAK1 activation and its correlation with E-cadherin/p120-catenin expression in a panel of NSCLC cell lines (Figure 3). For this purpose, we examined the expression of E-cadherin, p120-catenin, total PAK1 and p-PAK1(Thr423) in a panel of NSCLC cells. As expected, we observed an inverse correlation between E-cadherin/p120-catenin expression and the ratio of phospho-PAK1/total PAK1 in the examined panel of cell lines.Figure 3


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)

PAK1 activation is inversely correlated with E-cadherin and p120-catenin expression in NSCLC cells. A-Western blots demonstrating E-cadherin, p120-catenin, PAK1 and p-PAK1(Thr423) expression in a panel of NSCLC cells as well as immortalized normal human respiratory epithelial cells (BEAS-2B). B-Bar chart demonstrating signal intensity of p-PAK1/PAK1, p120-catenin and E-cadherin normalized to the value of BEAS-2B cells.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Fig3: PAK1 activation is inversely correlated with E-cadherin and p120-catenin expression in NSCLC cells. A-Western blots demonstrating E-cadherin, p120-catenin, PAK1 and p-PAK1(Thr423) expression in a panel of NSCLC cells as well as immortalized normal human respiratory epithelial cells (BEAS-2B). B-Bar chart demonstrating signal intensity of p-PAK1/PAK1, p120-catenin and E-cadherin normalized to the value of BEAS-2B cells.
Mentions: Furthermore, we examined PAK1 activation and its correlation with E-cadherin/p120-catenin expression in a panel of NSCLC cell lines (Figure 3). For this purpose, we examined the expression of E-cadherin, p120-catenin, total PAK1 and p-PAK1(Thr423) in a panel of NSCLC cells. As expected, we observed an inverse correlation between E-cadherin/p120-catenin expression and the ratio of phospho-PAK1/total PAK1 in the examined panel of cell lines.Figure 3

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