Evidence that arachidonate 15-lipoxygenase 2 is a negative cell cycle regulator in normal prostate epithelial cells.
15-Lipoxygenase 2 (15-LOX2) is a recently cloned human lipoxygenase that shows tissue-restricted expression in prostate, lung, skin, and cornea. The protein level and enzymatic activity of 15-LOX2 have been shown to be down-regulated in prostate cancers compared with normal and benign prostate tissues. The biological function of 15-LOX2 and the role of loss of 15-LOX2 expression in prostate tumorigenesis, however, remain unknown. We report the cloning and functional characterization of 15-LOX2 and its three splice variants (termed 15-LOX2sv-a, 15-LOX2sv-b, and 15-LOX2sv-c) from primary prostate epithelial cells. Western blotting with multiple primary prostate cell strains and prostate cancer cell lines reveals that the expression of 15-LOX2 is lost in all prostate cancer cell lines, accompanied by decreased enzymatic activity revealed by liquid chromatography/tandem mass spectrometry analyses. Further experiments show that the loss of 15-LOX2 expression results from transcriptional repression caused by mechanism(s) other than promoter hypermethylation or histone deacetylation. Subsequent functional studies indicate the following: 1) the 15-LOX2 product, 15(S)-hydroxyeicosatetraenoic acid, inhibits prostate cancer cell cycle progression; 2) 15-LOX2 expression in primary prostate epithelial cells is inversely correlated with cell cycle; and 3) restoration of 15-LOX2 expression in prostate cancer cells partially inhibits cell cycle progression. Taken together, these results suggest that 15-LOX2 could be a suppressor of prostate cancer development, which functions by restricting cell cycle progression.
Tang
Shaohua
S
Department of Carcinogenesis, the University of Texas MD Anderson Cancer Center, Science Park Research Division, Smithville, Texas 78957, USA.
Bhatia
Bobby
B
Maldonado
Carlos J
CJ
Yang
Peiying
P
Newman
Robert A
RA
Liu
Junwei
J
Chandra
Dhyan
D
Traag
Jeanine
J
Klein
Russell D
RD
Fischer
Susan M
SM
Chopra
Dharam
D
Shen
Jianjun
J
Zhau
Haiyen E
HE
Chung
Leland W K
LW
Tang
Dean G
DG
D017398:Alternative Splicing; D000595:Amino Acid Sequence; D001093:Arachidonate 15-Lipoxygenase / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D001483:Base Sequence; D002453:Cell Cycle / Q000502:physiology*; D002471:Cell Transformation, Neoplastic; D002478:Cells, Cultured; D003001:Cloning, Molecular; D017931:DNA Primers; D004847:Epithelial Cells / Q000166:cytology / Q000201:enzymology*; D014644:Genetic Variation; D005822:Genetic Vectors; D006801:Humans; D006893:Hydroxyeicosatetraenoic Acids / Q000378:metabolism; D007700:Kinetics; D008297:Male; D008969:Molecular Sequence Data; D011467:Prostate / Q000166:cytology / Q000201:enzymology*; D011471:Prostatic Neoplasms / Q000201:enzymology; D012333:RNA, Messenger / Q000235:genetics; D011994:Recombinant Proteins / Q000378:metabolism; D012016:Reference Values; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D014158:Transcription, Genetic
D017931:DNA Primers; D006893:Hydroxyeicosatetraenoic Acids; D012333:RNA, Messenger; D011994:Recombinant Proteins; C025984:15-hydroxy-5,8,11,13-eicosatetraenoic acid; C458528:ALOX15B protein, human; D001093:Arachidonate 15-Lipoxygenase