Caspase 8 and maspin are downregulated in breast cancer cells due to CpG site promoter methylation

<p>Abstract</p> <p>Background</p> <p>Epigenetic changes associated with promoter DNA methylation results in silencing of several tumor suppressor genes that lead to increased risk for tumor formation and for progression of the cancer.</p> <p>Methods</p> <p>Methylation specific PCR (MSP) and bisulfite sequencing were used for determination of proapoptotic gene Caspase 8 (CASP8) and the tumor suppressor gene maspin promoter methylation in four breast cancer and two non-tumorigenic breast cell lines. Involvement of histone H3 methylation in those cell lines were examined by CHIP assay.</p> <p>Results</p> <p>The CpG sites in the promoter region of CASP8 and maspin were methylated in all four breast cancer cell lines but not in two non-tumorigenic breast cell lines. Demethylation agent 5-aza-2'-deoxycytidine (5-aza-dc) selectively inhibits DNA methyltransferases, DNMT3a and DNMT3b, and restored CASP8 and maspin gene expression in breast cancer cells. 5-aza-dc also reduced histone H3k9me2 occupancy on CASP8 promoter in SKBR3cells, but not in MCF-7 cells. Combination of histone deacetylase inhibitor Trichostatin A (TSA) and 5-aza-dc significant decrease in nuclear expression of Di-methyl histone H3-Lys27 and slight increase in acetyl histone H3-Lys9 in MCF-7 cells. CASP8 mRNA and protein level in MCF-7 cells were increased by the 5-aza-dc in combination with TSA. Data from our study also demonstrated that treatment with 5-FU caused a significant increase in unmethylated CASP8 and in CASP8 mRNA in all 3 cancer lines.</p> <p>Conclusions</p> <p>CASP8 and maspin expression were reduced in breast cancer cells due to promoter methylation. Selective application of demethylating agents could offer novel therapeutic opportunities in breast cancer.</p

Ion exchanger modified PVC membranes-selectivity studies and response amplification of oxalate and lactate enzyme electrodes

We report on a novel method of oxidase enzyme electrode response amplification, using unplasticized PVC and plasticized PVC, respectively. The anion exchanger tricaprylylmethylammonium chloride (Aliquat 336s) and hydrophobic isopropylmyristate (IPM) plasticizer have been used together to modify PVC. Resulting structures are anionic substrate selective and hydrogen peroxide impermeable and can be used as outer membranes of a classical dual membrane amperometric enzyme electrode where an oxidase is used to generate HO for electrochemical detection. Their effect on sensor sensitivity and linearity is considered

Ion exchanger modified PVC membranes-selectivity studies and response amplification of oxalate and lactate enzyme electrodes

We report on a novel method of oxidase enzyme electrode response amplification, using unplasticized PVC and plasticized PVC, respectively. The anion exchanger tricaprylylmethylammonium chloride (Aliquat 336s) and hydrophobic isopropylmyristate (IPM) plasticizer have been used together to modify PVC. Resulting structures are anionic substrate selective and hydrogen peroxide impermeable and can be used as outer membranes of a classical dual membrane amperometric enzyme electrode where an oxidase is used to generate HO for electrochemical detection. Their effect on sensor sensitivity and linearity is considered

Development of an oxidase-based glucose sensor using thickness-shear-mode quartz crystals

A glucose biosensor has been developed which combines the substrate specificity offered by the enzyme glucose oxidase with the high sensitivity of a quartz crystal thickness-shear-mode sensor. Glucose is detected via the enzyme-catalysed formation of insoluble films of oxidised o-dianisidine on the crystal surface. Glucose levels can be measured in situ and the sensor has a fast response time of 80-100s with a linear response to glucose in the concentration range 30-200μM. Sensor sensitivity is of the order 4ΩμM glucose. The crystal is readily regenerated between assays. Copyright (C) 1998 Elsevier Science B.V

Development of an oxidase-based glucose sensor using thickness-shear-mode quartz crystals

A glucose biosensor has been developed which combines the substrate specificity offered by the enzyme glucose oxidase with the high sensitivity of a quartz crystal thickness-shear-mode sensor. Glucose is detected via the enzyme-catalysed formation of insoluble films of oxidised o-dianisidine on the crystal surface. Glucose levels can be measured in situ and the sensor has a fast response time of 80-100s with a linear response to glucose in the concentration range 30-200μM. Sensor sensitivity is of the order 4ΩμM glucose. The crystal is readily regenerated between assays. Copyright (C) 1998 Elsevier Science B.V