Enhancer of zeste homolog 2 induces pulmonary artery smooth muscle cell proliferation.
BACKGROUND
Pulmonary Arterial Hypertension (PAH) is a progressively devastating disease characterized by excessive proliferation of the Pulmonary Arterial Smooth Muscle Cells (PASMCs). Studies suggest that PAH and cancers share an apoptosis-resistant state featuring excessive cell proliferation. The proliferation of cancer cells is mediated by increased expression of Enhancer of Zeste Homolog 2 (EZH2), a mammalian histone methyltransferase that contributes to the epigenetic silencing of target genes. However, the role of EZH2 in PAH has not been studied. In this study, it is hypothesized that EZH2 could play a role in the proliferation of PASMCs.


METHODS
In the present study, the expression patterns of EZH2 were investigated in normal and hypertensive mouse PASMCs. The effects of EZH2 overexpression on the proliferation of human PASMCs were tested. PASMCs were transfected with EZH2 or GFP using nucleofector system. After transfection, the cells were incubated for 48 hours at 37°C. Proliferation and cell cycle analysis were performed using flow cytometry. Apoptosis of PASMCs was determined using annexin V staining and cell migration was tested by wound healing assay.


RESULTS
EZH2 protein expression in mouse PASMCs were correlated with an increase in right ventricular systolic pressure and Right Ventricular Hypertrophy (RVH). The overexpression of EZH2 in human PASMCs enhances proliferation, migration, and decrease in the rate of apoptosis when compared to GFP-transfected cells. In the G2/M phase of the EZH2 transfected cells, there was a 3.5 fold increase in proliferation, while there was a significant decrease in the rate of apoptosis of PASMCs, when compared to control.


CONCLUSIONS
These findings suggest that EZH2 plays a role in the migration and proliferation of PASMCs, which is a major hallmark in PAH. It also suggests that EZH2 could play a role in the development of PAH and can serve as a potential target for new therapies for PAH.
Division of Allergy and Immunology, Internal Medicine, Morsani College of Medicine, University of South Florida, Tampa, Florida, United States of America.
Salman A
SA
Aljubran
Ruan
R
Cox
Prasanna
P
Tamarapu Parthasarathy
Gurukumar
G
Kollongod Ramanathan
Venugopal
V
Rajanbabu
Huynh
H
Bao
Shyam S
SS
Mohapatra
Shyam M
SM
Mohapatra
Richard
R
Lockey
Narasaiah
N
Kolliputi
D000818:Animals; D017209:Apoptosis / Q000235:genetics; D002465:Cell Movement / Q000235:genetics; D049109:Cell Proliferation; D004195:Disease Models, Animal; D018450:Disease Progression; D000071221:Enhancer of Zeste Homolog 2 Protein; D015870:Gene Expression; D006801:Humans; D006976:Hypertension, Pulmonary / Q000235:genetics / Q000378:metabolism; D000860:Hypoxia; D051379:Mice; D008810:Mice, Inbred C57BL; D009131:Muscle, Smooth, Vascular / Q000378:metabolism*; D032389:Myocytes, Smooth Muscle / Q000378:metabolism*; D010641:Phenotype; D063151:Polycomb Repressive Complex 2 / Q000235:genetics / Q000378:metabolism*; D011651:Pulmonary Artery / Q000378:metabolism*
C498409:EZH2 protein, human; D000071221:Enhancer of Zeste Homolog 2 Protein; D063151:Polycomb Repressive Complex 2