OBJECTIVETo explore the proliferation and invasive effects of inhibitors of kinase 4(INK4)(P15(ink4b) and P16(ink4a)/CDKN2) gene protein activation on RKO human colorectal cell in vivo and in vitro.

METHODSRKO human colorectal cell line was exposed to the specific DNA methyltransferase inhibitor 5-Aza-CdR and INK4(P15(ink4b) and P16(ink4a)/CDKN2) protein expression was detected by Western blotting. Soft agar cloning experiment and Transwell chamber assay were used to detect the proliferative and invasive ability in vitro. Tumorigenicity in nude mice was analyzed in vivo.

RESULTSINK4(P15(ink4b) and P16(ink4a)/CDKN2) protein expression of RKO human colorectal cells after exposure to 1×10(-7), 5×10(-7) and 1×10(-6) mol/L 5-Aza-CdR concentrations(A, B, C groups) were 1.13, 1.38, 1.92 folds and 1.11, 1.45, 2.14 folds compared to positive control group respectively. Soft agar cloning experiment showed the number of cell colony significantly decreased from 36.8±5.1(positive control group) to 32.4±7.2, 21.3±5.4 and 19.5±6.4 (3 experiment groups, all P<0.05) respectively. Transwell chamber assay showed that migrated cell number in positive control group(67.4±7.2) was significantly higher than those of 3 experimental groups(35.3±4.6, 29.5±7.3 and 25.3±6.2, respectively). The tumor volume of metastasis model in nude mice was inhibited in experimental groups, but not significantly lower compared to control group (P>0.05). There were significant differences of tumor weight and inhibition rate between control group and 3 experimental groups in nude mice respectively(all P<0.01).

CONCLUSIONINK4(P15(ink4b) and P16(ink4a)/CDKN2) protein activation can inhibit tumor proliferation, migration and suppress the tumor formation ability.

Animals ; Cell Line, Tumor ; Cell Proliferation ; Colorectal Neoplasms ; metabolism ; pathology ; Cyclin-Dependent Kinase Inhibitor p15 ; genetics ; metabolism ; Cyclin-Dependent Kinase Inhibitor p16 ; genetics ; metabolism ; Humans ; Mice ; Mice, Inbred BALB C ; Neoplasm Metastasis ; Neoplasm Transplantation ; Transcriptional Activation

OBJECTIVETo study the effects of arsenic trioxide (As(2)O(3)) on cell cycle and expression of cyclin dependent kinase inhibitors (CDKIs) in multiple myeloma (MM) cells, and explore its pharmacological mechanism.

METHODSThe DNA content of MM cells line HS-Sultan was analyzed by flow cytometry after exposure to As(2)O(3), the effects on expression of CDKI P15, P16 AND P21 were studied by reverse transcriptase PCR.

RESULTSDNA flow cytometric analysis showed that As(2)O(3) induced most of HS-Sultan cells, arrest at G(0)/G(1) phase and a small fraction at G(2)/M phase and apoptosis occurred mainly in S phase. There was no expression of P15 and P16 mRNA in untreated HS-Sultan cells and 1.0 micromol/L As(2)O(3) could make them expressed after exposed 24 or 48 hours respectively. Expression of P12 mRNA was obviously elevated by As(2)O(3) comparing with that of control.

CONCLUSIONOne of the pharmacological mechanisms of As(2)O(3) is to activate the expression of CDKI P15, P16 and P21, and consequently affect cell proliferation cycle.

Antineoplastic Agents ; pharmacology ; Arsenicals ; pharmacology ; Cell Cycle ; drug effects ; physiology ; Cyclin-Dependent Kinase Inhibitor p15 ; biosynthesis ; genetics ; Cyclin-Dependent Kinase Inhibitor p16 ; biosynthesis ; genetics ; Cyclin-Dependent Kinase Inhibitor p21 ; biosynthesis ; genetics ; Humans ; Multiple Myeloma ; drug therapy ; metabolism ; pathology ; Oxides ; pharmacology ; RNA, Messenger ; genetics ; Tumor Cells, Cultured

OBJECTIVETo detect the presence of p15 antisense RNA(p15AS) in acute myeloid leukemia(AML).

METHODSp15AS and p15 mRNA in two leukemia cell lines was detected with strand-specific primer RT-qPCR. To explore the connection between p15AS and AML, 43 patients with newly diagnosed AML and 21 patients with benign diseases (Iron deficiency anemia) as controls were enrolled. The expression level of p15AS in bone marrow cells derived from the patients and the controls were determined by strand-specific primer RT-qPCR, and its relationship with clinical features was analyzed.

RESULTSThe two AML lines displayed high p15AS and low p15 expression. Samples derived from the AML patients showed relatively increased expression of p15AS and down-regulated p15 expression in their bone cells. In contrast, the 21 controls showed high expression of p15 but relatively low expression of the p15AS. Compared with the normal controls, the expression levels of p15 protein were significantly lower among the AML patients (P<0.01). No relationships were detected between the level of p15AS and the patient's age, gender, FAB subtype, total white blood cell count, platelet count, proliferative degree of bone marrow cell and karyotype classification (P>0.05 for all comparisons).

CONCLUSIONHigh expression of p15 antisense RNA was frequently found among AML patients, and may play an important role in epigenetic silencing of p15.

Adult ; Aged ; Bone Marrow Cells ; metabolism ; Cyclin-Dependent Kinase Inhibitor p15 ; genetics ; Epigenesis, Genetic ; Female ; Gene Expression Regulation, Neoplastic ; Humans ; Leukemia, Myeloid, Acute ; genetics ; metabolism ; Male ; Middle Aged ; RNA, Antisense ; genetics ; metabolism ; Up-Regulation ; Young Adult

BACKGROUND: Aberrant DNA hypermethylation plays a pivotal role in carcinogenesis and disease progression; therefore, accurate measurement of differential gene methylation patterns among many genes is likely to reveal biomarkers for improved risk assessment. We evaluated the gene hypermethylation profiles of primary breast tumors and their corresponding normal tissues and investigated the association between major clinicopathological features and gene hypermethylation. METHODS: A single reaction using methylation-specific multiplex ligation-dependent probe amplification was used to analyze the DNA methylation status of 24 tumor suppressor genes in 60 cancerous tissues and their corresponding normal tissues from patients with primary breast cancer. RESULTS: In cancerous breast tissues, 21 of 24 genes displayed promoter methylation in one or more samples. The most frequently methylated genes included RASSF1 (43.3%), APC (31.7%), CDKN2B (25.0%), CDH13 (23.3%), GSTP1 (16.7%), and BRCA1 (10%). APC was associated with lymph node metastasis, and BRCA1 was associated with negative estrogen receptor and negative progesterone receptor expression. In normal breast tissues, 8 of 24 tumor suppressor genes displayed promoter hypermethylation; CDKN2B (28.3%) and RASSF1 (8.3%) hypermethylation were most frequently observed. CONCLUSIONS: RASSF1 and CDKN2B hypermethylation in Korean breast cancer patients were the most frequent in cancerous tissue and corresponding normal tissue, respectively. Our data indicates that methylation of specific genes is a frequent event in morphologically normal breast tissues adjacent to breast tumors as well as the corresponding breast cancers. This study also suggests that gene methylation is linked to various pathological features of breast cancer; however, this requires confirmation in a larger study.
Adult ; Breast/metabolism ; Breast Neoplasms/*genetics/metabolism/pathology ; Cyclin-Dependent Kinase Inhibitor p15/genetics ; *DNA Methylation ; Female ; Humans ; Lymphatic Metastasis ; Middle Aged ; Promoter Regions, Genetic ; Republic of Korea ; Tumor Suppressor Proteins/genetics

This study was aimed to investigate the regulatory effect of phenylhexyl isothiocyanate (PHI) on methylation of histone H3K4, H3K9 and demethylation of p15 gene in acute leukemia cell line Molt-4, and to explore the possible mechanism inducing re-expression of silent gene. The methylation status of histone H3K4, H3K9 and the expression of P15 protein in the Molt-4 cells treated with PHI were detected by Western blot; the methylation status of p15 gene in the Molt-4 cells before and after treatment with PHI was determined by methylation specific polymerase chain reaction (MSP); the expression level of p15 gene mRNA in Molt-4 cells treated with PHI was assayed by semiquantitative reverse transcription-PCR. The results indicated that the PHI could increase methylation of histone H3K4 and decrease methylation of histone H3K9 in concentration-and time-dependent manners. After treatment of Molt-4 cells with PHI for 5 days, the methylation of p15 gene was reduced, the significant hypermethylation of p15 gene was reversed, the silenced p15 gene re-expressed; the expressions of p15 mRNA and P15 protein were enhanced in concentration-dependent manner. It is concluded that probably through specifically regulating the methylation level of histone H3K4 and H3K9, the PHI causes the changes of chromosome space structure and results in the demethylation of CPG island in p15 gene, thereby induces the re-expression of p15 gene which was silenced.
Cell Line, Tumor ; CpG Islands ; Cyclin-Dependent Kinase Inhibitor p15 ; genetics ; metabolism ; DNA Methylation ; drug effects ; Gene Expression Regulation, Leukemic ; drug effects ; Gene Silencing ; Histones ; genetics ; metabolism ; Humans ; Isothiocyanates ; pharmacology

To investigate the effect of 5-aza-2'-deoxycytidine (5-Aza-CdR) on cell of high-risk patients with myelodysplastic syndrome (MDS) in vitro, the growth inhibition of MUTZ-1 cell induced by 5-Aza-CdR was detected by MTT method; apoptosis was detected by morphological observation and translocation of phosphatidylserine (PS) was examined by flow cytometry assay; the expressions of P15INK4B, DNA methyltransferases (DNMT)(1), DNMT(3A) and DNMT(3B) gene on mRNA level were detected by RT-PCR; methylation of p15INK4B gene in MUTZ-1 cells was detected by PCR using methylation specific primer (MSP). The results showed that 5-Aza-CdR inhibited the growth of MUTZ-1 cells. The IC(50) values of 24, 48 and 72 hours were 6.75, 2.82 and 5.45 mmol/L respectively. Characteristic changes of apoptosis emerged in MUTZ-1 cells after being exposed to 5-Aza-CdR in the different concentration from 0.8 mmol/L to 3.2 mmol/L, and the positive cells of annexin V on the membrane of MUTZ-1 cells were analyzed by flow cytometry. 5-Aza-CdR could activate the p15INK4B gene expression in MUTZ-1 cells by demethylation of the p15INK4B gene in a dose-dependent manner after the cells were treated for 48 hours. Furthermore, 5-Aza-CdR could significantly down-regulate the expressions of DNA methyltransferase genes DNMT(3A) at mRNA level in a dose dependent manner. However, it had no effects on DNMT(1) gene and DNMT(3B) gene. It is concluded that 5-Aza-CdR can inhibit the growth of MUTZ-1 cells and induce the apoptosis of these cells within the range of concentration from 0.8 mmol/L to 3.2 mmol/L, which may be one of the mechanisms of antitumor effects of 5-Aza-CdR. The drug can activate the expression of p15INK4B gene in MUTZ-1 cells by demethylation of the p15INK4B gene through inhibiting the expression of DNMT(3A) gene. It may be the mechanism of 5-Aza-CdR in the treatments of MDS.
Azacitidine ; analogs & derivatives ; pharmacology ; Cell Cycle Proteins ; genetics ; Cell Line ; Cell Proliferation ; drug effects ; Cyclin-Dependent Kinase Inhibitor p15 ; DNA Methylation ; DNA Modification Methylases ; metabolism ; Humans ; Myelodysplastic Syndromes ; drug therapy ; pathology ; RNA, Messenger ; analysis ; Tumor Suppressor Proteins ; genetics

OBJECTIVETo detect the expression and the CpG island methylation status of tumor suppressor gene p15 after exposure to 1,4-benzoquinone (1,4-BQ) in primary cultivated C57BL/6J mouse bone marrow cells in vitro.

METHODSThe mouse bone marrow cells were isolated in vitro. The effect of 0, 0.1, 1, 5, 10, 20, and 40 µmol/L 1,4-BQ on cell viability (CKK-8) was detected. 0, 0.1, 1, 10 µmol/L 1,4-BQ were used to intoxicate the mouse bone marrow cells for 24 h; Real-time PCR was employed to analyze the mRNA expression level of p15; The bisulfite sequencing PCR (BSP) was used to look into the methylation status of CpG islands in p15 promoter region.

RESULTS1,4-BQ exhibited dose-dependent toxicity to mouse bone marrow cells, and the LC(50) was 8.3 µmol/L (95%CI: 4.6 - 10.6 µmol/L). The mRNA expression of p15 in 10 µmol/L group was only equivalent to 43% of control group. Compared with control group, the decrease of p15 mRNA expression in1 and 10 µmol/L concentration were obvious, and the differences had statistical significance (P < 0.05 or P < 0.01). BSP sequencing results were same between the exposure groups and control group, the 56 CpG sites on CpG islands remained in the state of unmethylated.

CONCLUSIONmRNA expression of p15 gene decreases after exposure to 1,4-BQ, but the CpG islands methylation status in promoter is not affected, suggesting that methylation does not participate in 1,4-BQ-mediated p15 gene expression decrease, other effect mechanisms still need to be investigated.

Animals ; Base Sequence ; Benzoquinones ; toxicity ; Bone Marrow Cells ; metabolism ; Cells, Cultured ; CpG Islands ; Cyclin-Dependent Kinase Inhibitor p15 ; genetics ; DNA Methylation ; Environmental Exposure ; Mice ; Mice, Inbred C57BL ; Promoter Regions, Genetic ; RNA, Messenger ; genetics

OBJECTIVETo analyze the promoter methylation levels of p15, CDH1, DAPK and HICI genes of patients with myelodysplastic syndrome (MDS) and explore the relationship between the level of methylation and clinical features.

METHODSDNA methylation levels of p15, CDH1, DAPK and HICI in peripheral blood (PB) or bone marrow (BM) samples from 52 MDS patients were detected by real-time quantitative PCR. The correlation of the methylation level with clinical features and hematological findings was analyzed. 38 de novo AML patients and 46 normal individuals served as controls.

RESULTSThe methylation levels of p15, CDH1, DAPK and HICI were 16.23 ± 21.69, 6.59 ± 9.39, 0.14 ± 0.11 and 7.81 ± 9.70 in BM, and 14.96 ± 20.16, 6.00 ± 9.26, 0.12 ± 0.14 and 6.74 ± 9.72 in PB, respectively from 18 MDS patients, and the difference between BM and PB was not statistically significant (P > 0.05). The methylation levels of p15 (14.70 ± 18.17) and CDH1 (6.61 ± 8.79) genes in high risk (RAEBI/II) MDS were significantly higher than in low risk (RCMD/RARS/5q-, p15: 1.99 ± 1.59, CDH1: 1.23 ± 1.14 and RCMD, p15: 3.02 ± 3.42, CDH1:1.53 ± 2.06) MDS or control (p15: 1.69 ± 1.82, CDH1: 1.01 ± 1.12) (P < 0.05). The methylation levels of DAPK gene had no difference among subtypes of MDS, and that of HIC1 gene only differed between RAEB I/II (9.16 ± 11.95) and control (2.49 ± 2.26) (P = 0.042). The difference of methylation levels of p15, CDH1, DAPK and HICI in BM was statistically significant among subtypes of MDS (P = 0.001, 0.003, 0.039, 0.023, respectively). And so did of p15 and DAPK in PB (P = 0.013, 0.006, respectively). The methylation level of p15 and CDH1 was significantly correlated with IPSS classification and blasts percentage in BM.

CONCLUSIONSp15 and CDH1 genes are special hypermethylation genes in MDS. Methylation level of HIC1 gene showed an upward tendency from low risk to high risk MDS.

Adult ; Aged ; Aged, 80 and over ; Apoptosis Regulatory Proteins ; genetics ; metabolism ; Cadherins ; genetics ; metabolism ; Calcium-Calmodulin-Dependent Protein Kinases ; genetics ; metabolism ; Case-Control Studies ; Cyclin-Dependent Kinase Inhibitor p15 ; genetics ; metabolism ; DNA Methylation ; Death-Associated Protein Kinases ; Female ; Humans ; Kruppel-Like Transcription Factors ; genetics ; metabolism ; Male ; Middle Aged ; Myelodysplastic Syndromes ; genetics ; metabolism ; Promoter Regions, Genetic ; Real-Time Polymerase Chain Reaction ; Young Adult

Previously, we found that high doses of genistein show an inhibitory effect on uterine leiomyoma (UtLM) cell proliferation. In this study, using microarray analysis and Ingenuity Pathways Analysis(TM), we identified genes (up- or down-regulated, > or = 1.5 fold, P < or = 0.001), functions and signaling pathways that were altered following treatment with an inhibitory concentration of genistein (50 microg/ml) in UtLM cells. Downregulation of TGF-beta signaling pathway genes, activin A, activin B, Smad3, TGF-beta2 and genes related to cell cycle regulation, with the exception of the upregulation of the CDK inhibitor P15, were identified and validated by real-time RT-PCR studies. Western blot analysis further demonstrated decreased protein expression of activin A and Smad3 in genistein-treated UtLM cells. Moreover, we found that activin A stimulated the growth of UtLM cells, and the inhibitory effect of genistein was partially abrogated in the presence of activin A. Overexpression of activin A and Smad3 were found in tissue samples of leiomyoma compared to matched myometrium, supporting the contribution of activin A and Smad3 in promoting the growth of UtLM cells. Taken together, these results suggest that down-regulation of activin A and Smad3, both members of the TGF-beta pathway, may offer a mechanistic explanation for the inhibitory effect of a high-dose of genistein on UtLM cells, and might be potential therapeutic targets for treatment of clinical cases of uterine leiomyomas.
Activins/*genetics/metabolism/pharmacology ; Anticarcinogenic Agents/*pharmacology ; Cell Line, Tumor ; Cell Proliferation/drug effects ; Cyclin-Dependent Kinase Inhibitor p15/genetics/metabolism ; Down-Regulation ; Female ; Genistein/*pharmacology ; Humans ; Leiomyoma/*metabolism ; Oligonucleotide Array Sequence Analysis ; Signal Transduction/drug effects ; Smad3 Protein/*genetics/metabolism ; Transforming Growth Factor beta/*genetics/metabolism ; Up-Regulation ; Uterine Neoplasms/*metabolism

This study is to investigate the effect of phenylhexyl isothiocyanate (PHI), which has been proved to be a novel histone deacetylase inhibitor (HDACi) recently, on gene p15 de novo expression in acute leukemia cell line Molt-4, and to further study its potential mechanism. Modified methylation specific PCR (MSP) was used to screen p15-M and p15-U mRNA. DNA methyltransferasel (DNMT1), 3A (DNMT3A), 3B (DNMT3B) and p15 mRNA were measured by RT-PCR. P15 protein was detected by Western blotting. Hypermethylation of gene p15 was reversed and activation transcription of gene p15 in Molt-4 was de novo after 5 days exposure to PHI in a concentration dependent manner. DNMT1 and DNMT3B were inhibited by exposure to PHI for 5 days (P < 0.05). Alteration of DNMT3A was not significant. It is showed that PHI could reverse hypermethylation of gene p15 and transcriptional activation of gene p15 is de novo by PHI. It may result from down-regulating DNA methyltransferases, DNMT1 and DNMT3B, or up-regulating the histone acetylation that allows chromatin unfolding and the accessibility of regulators for transcriptional activation in the p15 promoter.
Cell Line, Tumor ; Cyclin-Dependent Kinase Inhibitor p15 ; genetics ; metabolism ; DNA (Cytosine-5-)-Methyltransferases ; genetics ; metabolism ; DNA Methylation ; Histone Deacetylase Inhibitors ; pharmacology ; Humans ; Isothiocyanates ; pharmacology ; Precursor T-Cell Lymphoblastic Leukemia-Lymphoma ; genetics ; metabolism ; pathology ; RNA, Messenger ; metabolism ; Repressor Proteins ; genetics ; metabolism