PEA-15 induces autophagy in human ovarian cancer cells and is associated with prolonged overall survival.
Phospho-enriched protein in astrocytes (PEA-15) is a 15-kDa phosphoprotein that slows cell proliferation by binding to and sequestering extracellular signal-regulated kinase (ERK) in the cytoplasm, thereby inhibiting ERK-dependent transcription and proliferation. In previous studies of E1A human gene therapy for ovarian cancer, we discovered that PEA-15 induced the antitumor effect of E1A by sequestering activated ERK in the cytoplasm of cancer cells. Here, we investigated the role of PEA-15 in ovarian cancer tumorigenesis, the expression levels of PEA-15 in human ovarian cancer, and whether PEA-15 expression correlated with overall survival in women with ovarian cancer. We overexpressed PEA-15 in low-PEA-15-expressing cells and knocked down PEA-15 in high-PEA-15-expressing cells and analyzed the effects on proliferation, anchorage-independent growth, and cell cycle progression. We then assessed PEA-15 expression in an annotated tissue microarray of tumor samples from 395 women with primary epithelial ovarian cancer and tested whether PEA-15 expression was linked with overall survival. PEA-15 expression inhibited proliferation, and cell cycle analysis did not reveal apoptosis but did reveal autophagy, which was confirmed by an increase in LC3 cleavage. Inhibition of the ERK1/2 pathway decreased PEA-15-induced autophagy. These findings suggest that the antitumor activity of PEA-15 is mediated, in part, by the induction of autophagy involving activation of the ERK1/2 pathway. Multivariable analyses indicated that the women with high-PEA-15-expressing tumors survived longer than those with low-PEA-15-expressing tumors (hazard ratio, 1.973; P = 0.0167). Our findings indicate that PEA-15 expression is an important prognostic marker in ovarian cancer.
Bartholomeusz
Chandra
C
Breast Cancer Translational Research Laboratory, The University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030, USA.
Rosen
Daniel
D
Wei
Caimiao
C
Kazansky
Anna
A
Yamasaki
Fumiyuki
F
Takahashi
Takeshi
T
Itamochi
Hiroaki
H
Kondo
Seiji
S
Liu
Jinsong
J
Ueno
Naoto T
NT
D000328:Adult; D000368:Aged; D051017:Apoptosis Regulatory Proteins; D001343:Autophagy; D045744:Cell Line, Tumor; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D005260:Female; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000037:antagonists & inhibitors / Q000502:physiology*; D008875:Middle Aged; D010051:Ovarian Neoplasms / Q000401:mortality / Q000473:pathology*; D010750:Phosphoproteins / Q000037:antagonists & inhibitors / Q000502:physiology*; D010766:Phosphorylation; D011379:Prognosis; D034741:RNA, Small Interfering / Q000235:genetics
D051017:Apoptosis Regulatory Proteins; D047908:Intracellular Signaling Peptides and Proteins; C092039:PEA15 protein, human; D010750:Phosphoproteins; D034741:RNA, Small Interfering; D048049:Extracellular Signal-Regulated MAP Kinases