[Effect of Basil Polysaccharide on Histone H3K9me2 Methylation and Expression of G9a and JMJD1A in Hepatoma Cells Under Hypoxic Conditions].

OBJECTIVE: To study the effect of basil polysaccharide on the expression of histone methyltransferase G9a, demethylase JMJD1A and histone H3K9me2 methylation level in hepatoma cells MHCC97H and MHCC97L under hypoxic conditions, in order to explore the regulatory effect of basil polysaccharide on the epigenetics of hepatoma cells. METHODS: Cobalt chloride(CoCl2) was used to simulate hypoxic, MHCC97H and MHCC97L hepatoma cells hypoxia model was established in vitro,and then intervened with different concantration of basil polysaccharide intervened 24 h. The expression of HIF-1α, G9a and JMJD1A mRNA in hepatoma cells were detected by real time fluorescent quantitative PCR. The expression of HIF-lα, G9a, JMJD1A protein and histone H3K9me2 methylation level was detected by Western-blot method. RESULTS: Basil polysaccharide down-regulated the expression of HIF-lα, G9a, JMJD1A mRNA and protein and histone H3K9me2 methylation level in MHCC97H cells under hypoxic condition,and down-regulated the expression of HIF-lα mRNA and protein and histone H3K9me2 methylation level in MHCC97L cells under hypoxic condition(P <0. 05). CONCLUSION: Basil polysaccharide can regulate histone H3K9me2 methylation levels in hepatoma cells MHCC97H and MHCC97L which have different metastatic potential under hypoxic conditions. On hepatoma cell MHCC97H, the regulation of histone H3K9me2 methylation is associated with histone methyltransferase G9a and demethylase JMJDlA. In hepatoma cell MHCC97L, the regulation of histone H3K9me2 methylation was probably through other pathways.

Aspirin inhibits proliferation of gemcitabine-resistant human pancreatic cancer cells and augments gemcitabine-induced cytotoxicity.

AIM: To investigate whether aspirin is able to augment gemcitabine-induced cytotoxicity in human pancreatic cancer cells. METHODS: Two gemcitabine-insensitive human pancreatic cancer cell lines, PANC-1 and Capan-1, were used. Cells were treated with either aspirin or gemcitabine alone or both of them. Cell growth and apoptosis were determined by MTT assay, Annexin V or Hoechest 33258 staining. Cell cycle distribution was examined by flow cytometry. Western blot with specific phosphorylated protein antibodies was used to detect the activation of protein kinase. RT-PCR and Western blot were applied to assess the transcription and protein level for cyclin D1 and Bcl-2. RESULTS: Aspirin alone significantly inhibits the proliferation of PANC-1 cells by causing cell cycle arrest at G(1) phase. Aspirin potentiates the anti-survival effect of gemcitabine as well as its pro-apoptotic effect in PANC-1 cells, although aspirin per se does not trigger apoptosis. Aspirin inhibits GSK-3beta activation and suppresses the expression of its downstream gene products (cyclin D1 and Bcl-2), which are implicated in proliferation, survival and chemoresistance of pancreatic cancer. The effects of aspirin on Capan-1, were similar to that on PANC-1. CONCLUSION: Our results suggest that aspirin inhibits the proliferation of gemcitabine-resistant pancreatic cancer cells and augments the antisurvival effect of gemcitabine, probably by suppressing the activity of GSK-3beta and its downstream gene products.