Investigating the Stability of Six Phenolic TMZ Ester Analogues, Incubated in the Presence of Porcine Liver Esterase and Monitored by HPLC.

Previous published data from our group showed the encouraging in vitro activities of six phenolic temozolomide (TMZ) ester analogues (ES8-ES12 and ES14) with up to a five-fold increase in potency compared to TMZ against glioblastoma multiform cell lines and TMZ-resistant O-methylguanine-DNA methyl transferase (MGMT)-positive primary cells. This study investigated the stabilities of the six phenolic TMZ ester analogues in the presence of porcine liver esterase (PLE) as a hydrolytic enzyme, using high-performance liquid chromatography (HPLC), monitored by a diode-array detector (DAD). Determining the rates of hydrolysis of the esters provided a useful insight into the feasibility of progressing them to the next phase of drug development.

A novel series of phenolic temozolomide (TMZ) esters with 4 to 5-fold increased potency, compared to TMZ, against glioma cells irrespective of MGMT expression.

The standard of care treatment for patients diagnosed with glioblastoma multiforme (GBM) is temozolomide (TMZ). Tumour resistance to TMZ results in significantly limited clinical effectiveness. There is therefore an inherent need for alternatives to TMZ capable of overcoming resistance associated with MGMT and MMR.

Identifying Reliable Diagnostic/Predictive Biomarkers for Rheumatoid Arthritis.

Introduction And Objective: Elevated C-reactive protein is usually a good indicator of rheumatoid arthritis (RA); however, there are limitations that compromise its specificity and therefore there is an urgent need to identify more reliable diagnostic biomarkers to detect early stages of RA. In addition, identifying the correct therapeutic biomarker for the treatment of RA using methotrexate (MTX) would greatly increase the benefits experienced by the patients.

Materials And Methods: Primary normal synoviocytes human fibroblast-like synoviocytes (HFLS) and its phenotype rheumatic HFLS-RA cells were chosen for this study.

Could the Anti-Chaperone VER155008 Replace Temozolomide for Glioma Treatment.

Cancer inducible molecular chaperone HSP90 is of great importance as an anticancer target. Proteomic analysis showed that inhibiting HSP90 by the geldanamycin derivative, 17-AAG elevated the expression of the co-chaperone Hsp70. In this study we used HSP90 selective inhibitor 17-AAG and HSP70/90 dual inhibitor, VER155008 (VER) in U87-MG glioma cells.

Can RNAi-mediated hsp90α knockdown in combination with 17-AAG be a therapy for glioma?

Heat shock protein 90 promotes tumor progression and survival and has emerged as a vital therapeutic target. Previously we reported that the combinatorial treatment of 17AAG/sihsp90α significantly downregulated Hsp90α mRNA and protein levels in Glioblastoma Multiforme (GBM). Here we investigated the ability of cell penetrating peptide (Tat48-60 CPP)-mediated siRNA-induced hsp90α knockdown as a single agent and in combination with 17-allylamino-17-demethoxygeldanamycin (17-AAG) to induce tumor growth inhibition in GBM and whether it possessed therapeutic implications.

The complexity of identifying cancer stem cell biomarkers.

The efficacy of glioma therapy can be considerably improved if it eliminates cancer stem cells (CSCs); however, to achieve this, CSCs markers are required. This study investigated the influence of micro-environmental changes on CSCs in hypoxic, serum deprived U87-MG and the corresponding control cells. Proteomic analysis produced a wide dataset, depicting the changes that occur at the proteomic level in the differentiated and undifferentiated U87-MG cell line.

Proteomic studies coupled with RNAi methodologies can shed further light on the downstream effects of telomerase in glioma.

A comprehensive proteomic study utilizing 2D-DIGE and MALDI-TOF was used to assess the effect of inhibiting two different regulatory mechanisms of telomerase in glioma. RNAi was used to target hTERT and hsp90α. Inhibition of telomerase activity resulted in downregulation of various cytoskeletal proteins with correlative evidence of the involvement of telomerase in regulating the expression of vimentin.

A novel therapeutic strategy for the treatment of glioma, combining chemical and molecular targeting of hsp90a.

Hsp90a's vital role in tumour survival and progression, together with its highly inducible expression profile in gliomas and its absence in normal tissue and cell lines validates it as a therapeutic target for glioma. Hsp90a was downregulated using the post-transcriptional RNAi strategy (sihsp90a) and a post-translational inhibitor, the benzoquinone antibiotic 17-AAG. Glioblastoma U87-MG and normal human astrocyte SVGp12 were treated with sihsp90a, 17-AAG and concurrent sihsp90a/17-AAG (combined treatment).

Can hsp90alpha-targeted siRNA combined with TMZ be a future therapy for glioma?

Hsp90alpha's vital role in cell cycle progression and apoptosis together with its presence in gliomas and absence in normal tissue, make it a credible target for cancer therapy. Three sets of dsRNA oligos designed to align different regions of the hsp90alpha sequence were used to downregulate hsp90alpha. SiRNA 1, 2, and 3 resulted in significant levels of silencing of hsp90alpha after 48 hr treatment (p < .

Telomerase downregulation in cancer brain stem cell.

Cancer stem cells (CSCs) are a minute sub-population of self-renewing, immortal cells, which can be responsible for chemoresistance observed in the treatment of cancer. CSCs are similar to cancer cells requiring telomerase activity or alternative mechanisms for their proliferation and regeneration. This study explored the correlation between CD133 (stem cell marker) and telomerase expression using CD133+ cells isolated from the glioma GOS-3 cell line with magnetic affinity cell sorting (MACS).

To determine the cytotoxicity of chlorambucil and one of its nitro-derivatives, conjugated to prasterone and pregnenolone, towards eight human cancer cell-lines.

Four ester prodrugs derived from the bifunctional alkylating agent chlorambucil, and one of its nitro-derivatives, 3-nitrochlorambucil conjugated to prasterone and pregnenolone, were synthesized and tested for their cytotoxic activity against eight human cell lines, using the standard MTT assay. A comparison between the esters and the controls, namely chlorambucil and 3-nitrochlorambucil would suggest that all four esters possess to varying degrees, specificity towards the breast adenocarcinoma cell line (MDA-mb468) than the other seven cells' lines tested. The overall findings are encouraging since it infers that these lipophilic esters not only have the ability to traverse specific cell membranes but also exhibit cytotoxicity towards most of the cell lines tested.

Can the lack of HSP90alpha protein in brain normal tissue and cell lines, rationalise it as a possible therapeutic target for gliomas?

Despite studies suggesting a role for HSP90alpha in tumorigenesis, there are no reports as to its expression in normal human brain tissue. In this study, the expression of HSP90alpha was evaluated in both cell lines (3 gliomas and 2 controls) and brain tissue specimens of 10 patients (8 gliomas and 2 normal brain tissues). No HSP90alpha protein was detected in either normal cell lines or normal brain tissue.

Epigenetic silencing of telomerase and a non-alkylating agent as a novel therapeutic approach for glioma.

5-Aza-2'-deoxycytidine (5azadC) inhibits DNA methyltransferase and subsequently induces the expression of genes silenced by methylation. While treatment with 5azadC downregulated hTERT and upregulated MGMT expression in two glioma cell lines, there was no change in the expression of these two genes in the normal cell line. However, cell viability was reduced as a result of 5azadC treatment in all three cell lines.

Telomerase subunits expression variation between biopsy samples and cell lines derived from malignant glioma.

Although scientific advances have recognised the prognostic power of telomerase activity in different cancers, as yet there has been no investigation regarding the expression variation of telomerase subunits in glioma tissues and cell lines. In this study, a recurrent anaplastic ependymoma and seven glioblastoma biopsy samples, four cell lines and four controls including two normal brain tissues were analysed for telomerase subunit expression profiles together with telomerase activity. Since telomerase activity is linked to tumourgenesis, the genes were analysed with respect to their expression variation.

The simultaneous separation and determination of five quinolone antibiotics using isocratic reversed-phase HPLC: application to stability studies on an ofloxacin tablet formulation.

A rapid and reliable HPLC method was developed for the simultaneously separation and quantitation of five quinolones antibiotics; nalidixic acid, norfloxacin, ofloxacin, ciprofloxacin and lomefloxacin. All five tablet formulations of individual quinolone antibiotics were routinely assayed without interference. The calibration curves were linear (r2> or =0.