Knockdown of secretory phospholipase A2 IIa reduces lung cancer growth in vitro and in vivo.
OBJECTIVE
Group IIa secretory phospholipase A2 (sPLA2 IIa) plays a role in the malignant potential of several epithelial cancers. Nuclear factor kappa B (NF-κB) regulates cancer cell growth and is modulated by phospholipase activity in many cancer cells. We hypothesized that knockdown of sPLA2 in lung cancer cells would reduce cell proliferation and NF-κB activity in vitro and attenuate tumor growth in vivo.


METHODS
Two human non-small cell lung cancer cell lines (A549 and H358) were transduced with short hairpin RNA targeting sPLA2 group IIa. Quantitative reverse transcriptase-polymerase chain reaction and immunoblotting confirmed knockdown of sPLA2 IIa messenger RNA and protein, respectively. Cell proliferation was evaluated by the 5-bromo-2'-deoxyuridine DNA labeling assay. NF-κB phosphorylation was assayed by western blot. 1 × 10(6) of A549 or A549 sPLA2 knockdown cells were injected into the left flanks of nude mice (aged 6 to 8 weeks). Tumors were followed for 23 days, then removed and stained with hematoxylin and eosin, stained with Ki-67, and analyzed for sPLA2 IIa messenger RNA expression.


RESULTS
sPLA2 knockdown reduced NF-κB phosphorylation and tumor growth in vivo. A549 wild-type tumors grew twice as fast as knockdown tumors. Ki-67 staining was more prominent throughout the wild-type tumors compared with knockdown tumors. Explanted knockdown tumors maintained lower sPLA2 levels compared with wild-type, confirmed by reverse transcriptase-polymerase chain reaction.


CONCLUSIONS
Knockdown of sPLA2 IIa suppresses lung cancer growth in part by attenuating NF-κB activity. These findings justify further investigation into the cellular mechanisms of sPLA2 in lung cancer and its potential role as a therapeutic target.
Section of General Thoracic Surgery, Division of Cardiothoracic Surgery, Department of Surgery, University of Colorado School of Medicine, Aurora, CO, USA.
Jessica A
JA
Yu
David
D
Mauchley
Howard
H
Li
Xianzhong
X
Meng
Raphael A
RA
Nemenoff
David A
DA
Fullerton
Michael J
MJ
Weyant
D000818:Animals; D015153:Blotting, Western; D002289:Carcinoma, Non-Small-Cell Lung / Q000201:enzymology / Q000235:genetics / Q000473:pathology / Q000628:therapy*; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D015536:Down-Regulation; D055785:Gene Knockdown Techniques; D015316:Genetic Therapy / Q000379:methods*; D054501:Group II Phospholipases A2 / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D019394:Ki-67 Antigen / Q000378:metabolism; D008175:Lung Neoplasms / Q000201:enzymology / Q000235:genetics / Q000473:pathology / Q000628:therapy*; D008297:Male; D051379:Mice; D008819:Mice, Nude; D016328:NF-kappa B / Q000378:metabolism; D010766:Phosphorylation; D034622:RNA Interference; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013997:Time Factors; D014162:Transfection; D047368:Tumor Burden; D023041:Xenograft Model Antitumor Assays
D019394:Ki-67 Antigen; D016328:NF-kappa B; D012333:RNA, Messenger; D054501:Group II Phospholipases A2; C516287:PLA2G2A protein, human