Novel oligoamine analogues inhibit lysine-specific demethylase 1 and induce reexpression of epigenetically silenced genes.
OBJECTIVE
Abnormal DNA CpG island hypermethylation and transcriptionally repressive histone modifications are associated with the aberrant silencing of tumor suppressor genes. Lysine methylation is a dynamic, enzymatically controlled process. Lysine-specific demethylase 1 (LSD1) has recently been identified as a histone lysine demethylase. LSD1 specifically catalyzes demethylation of mono- and dimethyl-lysine 4 of histone 3 (H3K4), key positive chromatin marks associated with transcriptional activation. We hypothesized that a novel class of oligoamine analogues would effectively inhibit LSD1 and thus cause the reexpression of aberrantly silenced genes.


METHODS
Human colorectal cancer cells were treated with the oligoamines and changes in mono- and dimethyl-H3K4 and other chromatin marks were monitored. In addition, treated cells were evaluated for the reexpression of the aberrantly silenced secreted frizzled-related proteins (SFRP) Wnt signaling pathway antagonist genes. Finally, the effects of the LSD1 inhibitors were evaluated in an in vivo xenograft model.


RESULTS
Treatment of HCT116 human colon adenocarcinoma cells in vitro resulted in increased H3K4 methylation and reexpression of silenced SFRP genes. This reexpression is also accompanied by a decrease in H3K9me2 repressive mark. Importantly, cotreatment with low doses of oligoamines and a DNA methyltransferase inhibitor highly induces the reexpression of the aberrantly silenced SFRP2 gene and results in significant inhibition of the growth of established tumors in a human colon tumor model in vivo.


CONCLUSIONS
The use of LSD1-inhibiting oligoamine analogues in combination with DNA methyltransferase inhibitors represents a highly promising and novel approach for epigenetic therapy of cancer.
Huang
Yi
Y
The Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21231, USA.
Stewart
Tracy Murray
TM
Wu
Yu
Y
Baylin
Stephen B
SB
Marton
Laurence J
LJ
Perkins
Brandy
B
Jones
Richard J
RJ
Woster
Patrick M
PM
Casero
Robert A
RA
D000588:Amines / Q000737:chemistry; D000818:Animals; D045744:Cell Line, Tumor; D002843:Chromatin / Q000737:chemistry; D018899:CpG Islands; D019175:DNA Methylation; D015971:Gene Expression Regulation, Enzymologic; D020868:Gene Silencing; D056466:Histone Demethylases / Q000037:antagonists & inhibitors* / Q000737:chemistry; D006801:Humans; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D015398:Signal Transduction; D015265:Site-Specific DNA-Methyltransferase (Adenine-Specific) / Q000378:metabolism; D051153:Wnt Proteins / Q000378:metabolism
D000588:Amines; D002843:Chromatin; D051153:Wnt Proteins; D056466:Histone Demethylases; C495195:KDM1A protein, human; D015265:Site-Specific DNA-Methyltransferase (Adenine-Specific)