[Abstract ] Forkhead box(Fox) M1, as a member of the Fox transcription factor family, overexpresses in many kinds of canc-ers and is related to a variety of oncogenic signaling pathways.It plays an important role in the occurrence, progression and metastasis of cancer.FoxM1 has been a new target for cancer therapy research.

Objective To study the whole genome DNA methylation changes induced by low dose radiation (LDR) in mouse,and mRNA expression profiles of DNMT1 and MBD2 in peripheral blood mononuclear cell (PBMC) and tissues.Methods Thirty male BALB/c mice were randomly divided into 3 groups:control,single exposure (0.5 Gy),and fractionated exposure of 6 MV X-rays for 10 d (0.05 Gy/d × 10 d).Control mice were sham-treated.To determine the immediate (early) effect of irradiation,15 mice (5/group) were sacrificed 2 h after the last irradiation.The other 15 mice were sacrificed 1 month after the last irradiation (delayed effect).Before sacrifice,blood was sampled immediately.Kidney,liver,spleen,brain and lung tissues were collected.A global DNA methylation quantification Kit and highperformance liquid chromatography (HPLC) were used to investigate the methylation level in blood DNA.The expressions of DNMT1 and MBD2 were determined by RT-PCR.Results For the early effects of irradiation,as compared with controls,fractionated exposure to X-ray irradiation led to the significant depression of global DNA methylation level in blood (t =10.19 and 8.93,P ＜ 0.05).DNMT1 and MBD2 mRNA were down-regulated in PBMC,kidney and liver (t =5.06,3.01,3.97,12.25,3.50 and 3.73,P ＜0.05),and MBD2 was also down-regulated in spleen (t =3.03,P ＜ 0.05).However,no changes were observed in single exposed group.As for the delayed effects,the methylation levels of blood were not changed in the single or fractionated exposed groups,and only MBD2 mRNA was down-regulated in PBMC and brain of fractionated exposed group (t =3.52 and 2.85,P ＜ 0.05).Conclusions Fractionated LDR exposure can induce genome DNA hypomethylation,which is tissue-specific,and may be related with down-regulation of DNMT1 and MBD2.

Objective The invasion and metastasis of colon cancer often leads to treatment failure and mortality in patients . Our research is to investigate the influence of FoxM 1 to malignant human colon cancer line . Methods In two human colon cancer lines, the protein and mRNA expression levels of FoxM 1 were analyzed with the application of RT-PCR and Western blot , from which high-expressed HT-29 and low-expressed HCT-116 were determined.The expression of FoxM1 was down-regulated by RNA interfering in HT-29 and up-regulated by constructing overexpression transgenic line in HCT-116.The proliferation of the above cells was assayed by healing method;while the metastasis and invasion ability were examined by Transwell chamber assay . Results Two colon cancer lines were selected with high-expression or low-expression of FoxM1 separately named HT-29 and HCT-116.Application of PEX-2-FoxM1 raised after HCT-116 cells express FoxM1, cell scratches in HCT-116 experimetal group ([70.92 ±1.48]%) compared with HCT-116 control group([16.92 ±4.05]%)and HCT-116 blank control group([16.66 ±2.63]%) will markedly enhance its capabil-ity of healing (P<0.05), Transwell Chambers in membrane cells in HCT-116 experimetal group (186.0 ±6.8) compared with HCT-116 control group(42.0 ±2.0) and HCT-116 blank control grou (37.0 ± 2.2)was increased (P<0.05).On the other hand, the applied pG-PH-shFoxM1 can reduce FoxM1 expression in HT-29 cell, cell scrat-ches healing ability in HT-29 experimetal group ( [ 10 .37 ± 3.86]%) compared with HT-29 control group([34.63 ±2.35]%)and HT-29 blank control group([67.36 ±2.61]%) decreased significantly (P<0.05), Transwell Chambers in membrane cells in HT-29 experimetal group (53.0 ±1.8)compared with HT-29 control group(95.0 ±2.2)and HT-29 blank control grou(118.0 ±4.0) was also reduced (P<0.05). Conclusion The expression of FoxM1 is in close relation to the invasion and metastasis of CRC .The fact that the siRNA interfering FoxM1 could effectively inhibit the proliferation, metastasis and invasion, suggesting FoxM1 could po-tentially be a new molecular target for inhibiting the proliferation of human colon cancer line .

OBJECTIVETo study the methylation changes in promoter CpG islands induced by low-dose X-ray radiation (LDR).

METHODSTwenty male BALB/c mice were randomly divided into control and fractionated radiation group exposed to 6 MV X-ray for 10 days (0.05 Gy/day). All the mice were sacrificed 2 h after the last radiation on day 10, and blood samples were collected for detecting DNA methylation changes using Roche-NimbleGen mouse DNA methylation 3×720K Promoter Plus CpG Island Array. MeDIP-qPCR was used to further validate the methylation status of specific genes.

RESULTSA total of 811 genes were found to show specific hypermethylation in fractional radiation group as compared with the control group, involving almost all the main biological processes by GO analysis. Eight candidate genes (Rad23b, Tdg, Ccnd1, Ddit3, Llgl1, Rasl11a, Tbx2, and Slc6a15) were confirmed to be hypermethylated in LDR samples by MeDIP-qPCR, consistent with the results of the methylation chip study.

CONCLUSIONLDR induces promoter hypermethylation on specific genes, which may contribute to radiation-induced pathogenesis.

Animals ; CpG Islands ; radiation effects ; DNA Methylation ; Dose-Response Relationship, Radiation ; Genome ; Male ; Mice ; Mice, Inbred BALB C ; X-Rays