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Lysine-specific demethylase 1 (LSD1) has been identified and biochemically characterized in epigenetics; however, the pathological roles of its dysfunction in mantle cell lymphoma (MCL) and T-cell acute lymphoblastic leukemia remain to be elucidated. In this study, we evaluated LSD1, and histone H3 lysine 4 (H3K4)me1 and H3K4me2 expression in patients with MCL and silenced LSD1 in JeKo‑1 and MOLT‑4 cells, in order to define its role in JeKo‑1 and MOLT‑4 cell proliferation and apoptosis. We retrospectively analyzed the protein expression of LSD1, and mono- and dimethylated H3K4 (H3K4me1 and H3K4me2), and cyclin D1 and Ki67 in 30 cases of MCL by immunohistochemistry. The correlation of LSD1, H3K4me1 and H3K4me2 with Ki67 was determined by statistical analysis. LSD1 was silenced by small interfering RNA (siRNA). Cell apoptosis and cell proliferation were detected by flow cytometry and 3-(4,5-dimethylthiazol‑2-yl)‑2,5-diphenyltetrazolium bromide (MTT) assay. The protein expression levels of LSD1, histone methylated H3K4, histone acetylated H3, cyclin D1, apoptotic proteins, p15 and DNA methyltransferase 1 (DNMT1) were examined by western blot analysis. We demonstrated that LSD1 was upregulated, and that H3K4me1 and H3K4me2 were downregulated in the cases with MCL, compared to those with proliferative lymphadenitis (p<0.05). LSD1 positively correlated with Ki67 in MCL [Cohen's kappa (κ)=0.667, p<0.01]. There was no significant correlation between H3K4me1 and H3K4me2, and Ki67 (κ=-0.182, p>0.05, κ=-0.200, p>0.05). The silencing of LSD1 decreased the levels of the apoptosis-related proteins, Bcl-2, pro-caspase-3 and C-myc, and decreased those of DNMT1 and increased p15, and resulted in the loss of cell viability and the induction apoptosis. The silencing of LSD1 increased the expression of H3K4me1 and H3K4me2, and histone acetylated H3 in the JeKo‑1 and MOLT‑4 cells. LSD1 siRNA also decreased cyclin D1 expression in the JeKo‑1 cells. On the whole, our findings demonstrate that the overexpression of LSD1 may be associated with the pathogenesis in MCL. We demonstrated that the silencing of LSD1 is capable of removing the mono- and dimethyl groups from H3K4, and upregulating the histone acetylation of H3 in JeKo‑1 and MOLT‑4 cells. The silencing of LSD1 inhibited cell growth and induced cell apoptosis. Of note, in JeKo‑1 cells, the silencing of LSD1 decreased cyclin D1 expression, which is one of the genes that contribute to the pathogenesis of MCL. LSD1 may thus be a possible therapeutic target in MCL and acute lymphoblastic leukemia MOLT‑4 cells.

In recent years, the role of epigenetic modifications in tumorigenesis drawn more and more attention. The aberrant changes of histone modifications have been found in leukemias, whereby loss of balance in H3K9 methylation is associated closely with leukemogenesis. SUV39H1, the first described histone H3 lysine 9 methyltransferase takes part in heterochromatin formation and gene transcription regulation. It could be a new target for leukemia therapy by correcting the aberrance of H3K9 methylation, inducing the reexpression of tumor suppressor genes. This review discusses how H3K9 methylation regulating gene transcription, silencing gene expression and its association with leukemia.

This study was purposed to investigate the effects of phenylhexyl isothiocyanate (PHI) on Burkitt lymphoma Daudi cell line and regulation of histone acetylation and methylation in Daudi cells, and to explore the potential mechanism. The apoptotic rate of Daudi cells treated with PHI was measured by flow cytometry, the changes of histone H3 and H4 acetylation, histone H3K9 and H3K4 methylation in Daudi cells treated with PHI were detected by Western blot. The results showed that PHI could induce apoptosis of Daudi cells, increased the acetylation level of H3 and H4, enhanced the methylation of H3K4, but reduced the methylation of H3K9. It is concluded that the PHI can up-regulate the acetylation level of histone H3 associated with transcription stimulation and the methylation of histone H3K4, down-regulate the methylation on histone H3K9 associated with transcription inhibition, promotes the apoptosis of Daudi cells. PHI may be a potential agent for target therapy of lymphoma.

Objective: To investigate the effect of phenylhexyl isothiocyanate (PHI) on histone acetylation and apoptosis in hepatocellular carcinoma cell line (SMMC-7721) in vitro., Methods: The viability of SMMC-7721 cells was determined by trypan blue exclusion. Apoptotic cells were assessed by TUNEL assay. The proteins of Bcl-2, Procaspase-9, Procaspase-8, Procaspase-3, caspase-9, caspase-3, histone acetylated H3 and H4 were detected by Western blot., Results: Compared with the vehicle control, PHI at 5, 10, 20, 40 and 80 µmol/L reduced the cell viability of SMMC-7721 cells in a concentration-dependent manner. PHI induced apoptosis in SMMC-7721 cells. An increased amount of apoptotic cells was detected after 7 hours exposure to PHI at 10, 20, and 40 µmol/L, 6.9% ± 2.4%, 17.5% ± 4.2% and 54.5% ± 5.4%, respectively, while that of the vehicle control was 4.5% ± 2.3% (P < 0.05). Along with the prolongation of time and increase of dose, the expressions of bcl-2, procaspase-9, procaspase-3 were decreased, that of caspase-9 and caspase-3 was increased. In contrast, alteration of procaspase-8 was not significant at those concentrations. PHI accumulated acetylated histone H3 and H4. After 3 hours exposure to PHI at 10, 20 and 40 µmol/L, the level of histone acetylated H3 was 1.87-, 2.43-, 3.67-fold increased and histone acetylated H4 was 1.29-, 1.45-, and 2.25-fold increased, compared with that of the vehicle control. The protein of histone acetylated H3 and H4 was significantly accumulated after 7 hours exposure., Conclusion: PHI is a new histone deacetylation inhibitor. It may induce accumulation of histone acetylation H3 and H4, inhibit cell growth and induce apoptosis in SMMC-7721 cells via the mitochondrial pathway.

Objective: To study the aberration in histone H3K4 and H3K9 methylation and H3 and H4 acetylation in human acute leukemia (AL) cells., Methods: The histone H3K4 and H3K9 methylation and H3 and H4 acetylation were detected by Western blot in 34 AL patients and 13 controls (9 non leukemia patients, 4 healthy volunteers)., Results: The level of H3K4 methylation was significantly lower in 19 AL patients than in non leukemia (0.220 ± 0.096 vs 0.447 ± 0.186, P < 0.01), while the level of H3K9 methylation was significantly higher (0.409 ± 0.106 vs 0.168 ± 0.015, P < 0.01); Both level of histone H3 and H4 acetylation in 15 AL patients were significantly lower (H3: 0.128 ± 0.013 vs 0.386 ± 0.104, H4: 0.096 ± 0.008 vs 0.341 ± 0.096, respectively, both P < 0.01)., Conclusion: Aberration of histone methylation and deficient histone acetylation in AL may represent the markers for an aberrant post-translational modification of histones and chromatin structure. It might be a potential epigenetic target for anti-leukemia agent.

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.

Objective: To investigate the effects of PHI on histone acetylation and methylation in hepatocellular carcinoma line SMMC-7721 cells., Methods: Apoptosis was measured by TUNNEL assay. Histone methylation and acetylation were detected by Western blot., Results: PHI inhibited cells growth and induced apoptosis. PHI treatment resulted in increased acetylation of histone H3 and H4 , elevated level of histone H3 lysine 4 methylation, and decreased level of histone H3 lysine 9 methylation., Conclusions: PHI can modulate both histone acetylation and methylation, which could remodel chromatin structure. PHI may be a novel anticancer drug.

Objective: To investigate the effect of phenyl-hexyl isothiocyanate (PHI) on acetylation and methylation of histone in acute lymphoblastic leukemia cell line Molt4., Methods: The inhibition of cell proliferation was observed by MTT method and clone suppression test. Apoptosis and cell cycle arrest were measured by flow cytometry. The alterations in histone acetyltransferase and acetylation and methylation of histones were detected by Western blot., Results: PHI could up-regulate the expression of acetyltransferase (P300/CBP), markedly induced the accumulation of acetylated histone H3, H4 and methylated histone H3 lysine 4 (H3K4), and inhibited methylation on lysine 9 of H3 (H3K9). The epigenetic regulation resulted in cell cycle arrest at G0/G1 phase, and induction of apoptosis., Conclusions: PHI can modulate both histone methylation and acetylation. It may serve as a histone deacetylase inhibitor, and might be a potential novel anti-leukemia agent.