TY - JOUR
T1 - PKCδ regulates integrin αVβ3 expression and transformed growth of K-ras dependent lung cancer cells
AU - Symonds, Jennifer M.
AU - Ohm, Angela M.
AU - Tan, Aik Choon
AU - Reyland, Mary E.
N1 - Funding Information:
This work was supported by a United Against Lung Cancer research award, a pilot grant from NIH Lung SPORE grant P50 CA58187, and R01DE015648 to MER.
PY - 2016
Y1 - 2016
N2 - We have previously shown that Protein Kinase C delta (PKCδ) functions as a tumor promoter in non-small cell lung cancer (NSCLC), specifically in the context of K-ras addiction. Here we define a novel PKCδ -> integrin αVβ3 -> Extracellular signal- Regulated Kinase (ERK) pathway that regulates the transformed growth of K-ras dependent NSCLC cells. To explore how PKCδ regulates tumorigenesis, we performed mRNA expression analysis in four KRAS mutant NSCLC cell lines that stably express scrambled shRNA or a PKCδ targeted shRNA. Analysis of PKCδ-dependent mRNA expression identified 3183 regulated genes, 210 of which were specifically regulated in K-ras dependent cells. Genes that regulate extracellular matrix and focal adhesion pathways were most highly represented in this later group. In particular, expression of the integrin pair, αVβ3, was specifically reduced in K-ras dependent cells with depletion of PKCδ, and correlated with reduced ERK activation and reduced transformed growth as assayed by clonogenic survival. Re-expression of PKCδ restored ITGAV and ITGB3 mRNA expression, ERK activation and transformed growth, and this could be blocked by pretreatment with a αVβ3 function-blocking antibody, demonstrating a requirement for integrin αVβ3 downstream of PKCδ. Similarly, expression of integrin aV restored ERK activation and transformed growth in PKCδ depleted cells, and this could also be inhibited by pretreatment with PD98059. Our studies demonstrate an essential role for αVβ3 and ERK signaling downstream of PKCδ in regulating the survival of K-ras dependent NSCLC cells, and identify PKCδ as a novel therapeutic target for the subset of NSCLC patients with K-ras dependent tumors.
AB - We have previously shown that Protein Kinase C delta (PKCδ) functions as a tumor promoter in non-small cell lung cancer (NSCLC), specifically in the context of K-ras addiction. Here we define a novel PKCδ -> integrin αVβ3 -> Extracellular signal- Regulated Kinase (ERK) pathway that regulates the transformed growth of K-ras dependent NSCLC cells. To explore how PKCδ regulates tumorigenesis, we performed mRNA expression analysis in four KRAS mutant NSCLC cell lines that stably express scrambled shRNA or a PKCδ targeted shRNA. Analysis of PKCδ-dependent mRNA expression identified 3183 regulated genes, 210 of which were specifically regulated in K-ras dependent cells. Genes that regulate extracellular matrix and focal adhesion pathways were most highly represented in this later group. In particular, expression of the integrin pair, αVβ3, was specifically reduced in K-ras dependent cells with depletion of PKCδ, and correlated with reduced ERK activation and reduced transformed growth as assayed by clonogenic survival. Re-expression of PKCδ restored ITGAV and ITGB3 mRNA expression, ERK activation and transformed growth, and this could be blocked by pretreatment with a αVβ3 function-blocking antibody, demonstrating a requirement for integrin αVβ3 downstream of PKCδ. Similarly, expression of integrin aV restored ERK activation and transformed growth in PKCδ depleted cells, and this could also be inhibited by pretreatment with PD98059. Our studies demonstrate an essential role for αVβ3 and ERK signaling downstream of PKCδ in regulating the survival of K-ras dependent NSCLC cells, and identify PKCδ as a novel therapeutic target for the subset of NSCLC patients with K-ras dependent tumors.
KW - Anchorage independent growth
KW - Integrins
KW - KRAS
KW - Lung cancer
KW - PKCδ
UR - http://www.scopus.com/inward/record.url?scp=84975502822&partnerID=8YFLogxK
U2 - 10.18632/oncotarget.7560
DO - 10.18632/oncotarget.7560
M3 - Article
C2 - 26918447
AN - SCOPUS:84975502822
VL - 7
SP - 17905
EP - 17919
JO - Oncotarget
JF - Oncotarget
SN - 1949-2553
IS - 14
ER -