Selection of the best blood compartment to measure cytidine deaminase activity to stratify for optimal gemcitabine or cytarabine treatment.

Cytidine deaminase (CDA) plays a crucial role in the degradation of cytidine analogs, such as gemcitabine and cytarabine. Several studies showed that a low CDA activity is associated with more toxicity but a higher efficacy, while a high activity will lead to a lower efficacy but less toxicity. A stratified dosing strategy based on the relative CDA activity would increase efficiency.

Metabolism, mechanism of action and sensitivity profile of fluorocyclopentenylcytosine (RX-3117; TV-1360).

A novel cytidine analog fluorocyclopentenylcytosine (RX-3117; TV-1360) was characterized for its cytotoxicity in a 59-cell line panel and further characterized for cytotoxicity, metabolism and mechanism of action in 15 additional cancer cell lines, including gemcitabine-resistant variants. In both panels sensitivity varied 75-fold (IC50: 0.4- > 30 μM RX-3117).

Decay of γ-H2AX foci correlates with potentially lethal damage repair in prostate cancer cells.

To determine the relationship between ionizing radiation-induced levels of γ-H2AX foci and cell survival in cultured prostate cancer cell lines, three prostate cancer cell lines: LNCaP (wt TP53), DU145 (mut TP53) and PC3 (TP53 null), were studied. For γ-H2AX foci induction, cells were irradiated with a single dose of 2 Gy and foci levels were studied at 30 min and 24 h after irradiation. Cell survival was determined by clonogenic assay, directly and 24 h after irradiation with doses ranging from 0 to 8 Gy.

Metabolism and accumulation of the lipophilic deoxynucleoside analogs elacytarabine and CP-4126.

Cytarabine (ara-C) and gemcitabine (dFdC) are commonly used anticancer drugs, which depend on the equilibrative (ENT) and concentrative-nucleoside-transporters to enter the cell. To bypass transport-related drug resistance, lipophilic derivatives elacytarabine (CP-4055), ara-C-5'elaidic-acid-ester, and CP-4126, (CO 1.01) gemcitabine-5'elaidic-acid-ester, were investigated for the entry into the cell, distribution, metabolism and retention.

Trifluorothymidine resistance is associated with decreased thymidine kinase and equilibrative nucleoside transporter expression or increased secretory phospholipase A2.

Trifluorothymidine (TFT) is part of the novel oral formulation TAS-102, which is currently evaluated in phase II studies. Drug resistance is an important limitation of cancer therapy. The aim of the present study was to induce resistance to TFT in H630 colon cancer cells using two different schedules and to analyze the resistance mechanism.

Cellular pharmacology of multi- and duplex drugs consisting of ethynylcytidine and 5-fluoro-2'-deoxyuridine.

Prodrugs can have the advantage over parent drugs in increased activation and cellular uptake. The multidrug ETC-L-FdUrd and the duplex drug ETC-FdUrd are composed of two different monophosphate-nucleosides, 5-fluoro-2'deoxyuridine (FdUrd) and ethynylcytidine (ETC), coupled via a glycerolipid or phosphodiester, respectively. The aim of the study was to determine cytotoxicity levels and mode of drug cleavage.

Oxaliplatin activity in selected and unselected human ovarian and colorectal cancer cell lines.

Oxaliplatin is used for treatment of colon cancer in combination with 5-fluorouracil or irinotecan. Oxaliplatin has similar, but also different resistant mechanisms as cisplatin. We studied the activity of oxaliplatin in ovarian and colon cancer cells with different resistance patterns to cisplatin.