DNA methyltransferase 1 is essential for initiation of the colon cancers.
DNA methyltransferase 1 (Dnmt1) is essential for the maintenance of hematopoietic and somatic stem cells in mice; however, its roles in human cancer stem-like cells (CSCs)/cancer-initiating cells (CICs) are still elusive. In the present study, we investigated DNMT1 functions in the maintenance of human colon CSCs/CICs using the human colon cancer cell line HCT116 (HCT116 w/t) and its DNMT1 knockout cell line (DNMT1(-/-)). The rates of CSCs/CICs were evaluated by side population (SP) analysis, ALDEFLUOR assay and expression of CD44 and CD24. SP, ALDEFLUOR-positive (ALDEFLUOR(+)) and CD44-positive and CD24-positive (CD44(+)CD24(+)) cell rates were lower in DNMT1(-/-) cells than in HCT116 w/t cells. Since CSCs/CICs have higher tumor-initiating ability than that of non-CSCs/CICs, the tumor-initiating abilities were addressed by injecting immune deficient (NOD/SCID) mice. DNMT1(-/-) cells showed less tumor-initiating ability than did HCT116 w/t cells, whereas the growing rate of DNMT1(-/-) cells showed no significant difference from that of HCT116 cells both in vitro and in vivo. Similar results were obtained for cells in which DNMT1 had been transiently knocked-down using gene-specific siRNAs. Taken together, these results indicate that DNMT1 is essential for maintenance of colon CSCs/CICs and that short-term suppression of DNMT1 might be sufficient to disrupt CSCs/CICs.
Department of Pathology, Sapporo Medical University School of Medicine, South-1 West-17, Chuo-Ku, Sapporo 060-8556, Japan.
Rena
R
Morita
Yoshihiko
Y
Hirohashi
Hiromu
H
Suzuki
Akari
A
Takahashi
Yasuaki
Y
Tamura
Takayuki
T
Kanaseki
Hiroko
H
Asanuma
Satoko
S
Inoda
Toru
T
Kondo
Satoshi
S
Hashino
Tadashi
T
Hasegawa
Takashi
T
Tokino
Minoru
M
Toyota
Masahiro
M
Asaka
Toshihiko
T
Torigoe
Noriyuki
N
Sato
D000818:Animals; D051927:CD24 Antigen / Q000096:biosynthesis; D002471:Cell Transformation, Neoplastic; D003110:Colonic Neoplasms / Q000201:enzymology* / Q000235:genetics / Q000473:pathology*; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000235:genetics / Q000378:metabolism*; D055785:Gene Knockdown Techniques; D045325:HCT116 Cells; D006801:Humans; D018960:Hyaluronan Receptors / Q000096:biosynthesis; D051379:Mice; D016688:Mice, Inbred NOD; D016513:Mice, SCID; D009368:Neoplasm Transplantation; D014411:Neoplastic Stem Cells / Q000502:physiology*; D034622:RNA Interference; D034741:RNA, Small Interfering; D023041:Xenograft Model Antitumor Assays
D051927:CD24 Antigen; D018960:Hyaluronan Receptors; D034741:RNA, Small Interfering; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases; C000619380:DNMT1 protein, human; C000619381:Dnmt1 protein, mouse