Role of genomic factors beyond thymidylate synthase in the prediction of response to 5-fluorouracil.

5-Fluorouracil (5FU) is still a major drug in combinations regimens for the treatment of colorectal cancer (CRC) both in the adjuvant and palliative setting. 5FU or its oral prodrug capecitabine is usually combined with irinotecan/oxaliplatin and the novel agents bevacizumab/cetuximab. Although this improved the outcome, the overall prognosis in patients with metastasized disease is still relatively poor. Although the target for 5FU, thymidylate synthase was shown to have a predictive value, this could only predict response in a subset of patients. Given the heterogeneous and complex nature of CRC, it is likely that other aberrations can affect therapeutic response. As an alternative, we investigated Copy number alterations using oligonucleotide-based high-throughput array-comparative-genomic-hybridization (aCGH) to obtain an unbiased screening of the whole genetic spectrum. Chromosomal aberrations have been identified in 85% of CRC patients and include genomic regions harboring copy number alterations in the DNA. These alterations may change the expression of many genes and might explain the differential response to therapy as shown in recent studies with several 5FU combinations. In order to clarify new predictive parameters for 5FU, we used aCGH in a historical cohort of patients, which received treatment with single agent 5FU, and an unsupervised clustering analysis showed a statistical (p < 0.05) difference between responding and nonresponding patients. We also find that several regions showed differences between responders/non-responders, such as losses in 12p12.3-12q15 and in 18p (where TS is located) in responding patients. Genome-wide analysis may provide an additional tool to discriminate between responders and nonresponders.

Synergistic interaction of novel lactate dehydrogenase inhibitors with gemcitabine against pancreatic cancer cells in hypoxia.

BACKGROUND: Hypoxia is a driving force in pancreatic-ductal-adenocarcinoma (PDAC) growth, metastasis and chemoresistance. The muscle-isoform of lactate dehydrogenase (LDH-A) constitutes a major checkpoint for the switch to anaerobic glycolysis, ensuring supply of energy and anabolites in hypoxic-environments. Therefore, we investigated the molecular mechanisms underlying the pharmacological interaction of novel LDH-A inhibitors in combination with gemcitabine in PDAC cells. METHODS: Lactate dehydrogenase A levels were studied by quantitative RT-PCR, western blot, immunofluorescence and activity assays in 14 PDAC cells, including primary-cell-cultures and spheroids, in normoxic and hypoxic conditions. Cell proliferation, migration and key determinants of drug activity were evaluated by sulforhodamine-B-assay, wound-healing assay, PCR and LC-MS/MS. RESULTS: Lactate dehydrogenase A was significantly increased under hypoxic conditions (1% O2), where the novel LDH-A inhibitors proved to be particularly effective (e.g., with IC50 values of 0.9 vs 16.3 µM for NHI-1 in LPC006 in hypoxia vs normoxia, respectively). These compounds induced apoptosis, affected invasiveness and spheroid-growth, reducing expression of metalloproteinases and cancer-stem-like-cells markers (CD133+). Their synergistic interaction with gemcitabine, with combination index values <0.4 in hypoxia, might also be attributed to modulation of gemcitabine metabolism, overcoming the reduced synthesis of phosphorylated metabolites. CONCLUSION: Lactate dehydrogenase A is a viable target in PDAC, and novel LDH-A inhibitors display synergistic cytotoxic activity with gemcitabine, offering an innovative tool in hypoxic tumours.

Correlation of cytidine deaminase polymorphisms and activity with clinical outcome in gemcitabine-/platinum-treated advanced non-small-cell lung cancer patients.

BACKGROUND: The aim of this study was to evaluate whether cytidine deaminase (CDA) polymorphisms 79A>C and 435C>T and/or CDA enzymatic activity influenced clinical outcome in 126 advanced non-small-cell lung cancer patients treated with gemcitabine-platinum-regimens. PATIENTS AND METHODS: CDA polymorphisms and activity were analysed by PCR and high-performance liquid chromatography, respectively. Univariate and multivariate analyses compared biological/clinical parameters with response, clinical benefit, time to progression (TtP) and overall survival (OS) using Pearson's χ(2) test, log-rank test and Cox proportional hazards model. RESULTS: Patients with CDA A79A/A79C genotypes had significantly longer TtP (6.0 versus 3.0 months; P = 0.001) and OS (11.0 versus 5.0 months; P = 0.001) than patients with C79C genotype. Patients harbouring CDA C435C/C435T genotypes also had a longer OS (P = 0.025), but no correlations were observed with TtP. Conversely, patients with low-CDA activity had a significantly higher response rate (37.7% versus 13.8%; P = 0.006), clinical benefit (91.8% versus 51.7%; P < 0.001), as well as longer TtP (8.0 versus 3.0 months; P < 0.001) and OS (19.0 versus 6.0 months; P < 0.001). Furthermore, enzymatic activity emerged as an independent predictor for death/progression risk at multivariate analysis. CONCLUSIONS: CDA enzymatic activity appears to be the strongest candidate biomarker of activity and efficacy of platinum-gemcitabine-based chemotherapy and should be validated in a prospective study.

Preclinical emergence of vandetanib as a potent antitumour agent in mesothelioma: molecular mechanisms underlying its synergistic interaction with pemetrexed and carboplatin.

BACKGROUND: Although pemetrexed, a potent thymidylate synthase (TS) inhibitor, enhances the cytoytoxic effect of platinum compounds against malignant pleural mesothelioma (MPM), novel combinations with effective targeted therapies are warranted. To this end, the current study evaluates new targeted agents and their pharmacological interaction with carboplatin-pemetrexed in human MPM cell lines. METHODS: We treated H2052, H2452, H28 and MSTO-211H cells with carboplatin, pemetrexed and targeted compounds (gefitinib, erlotinib, sorafenib, vandetanib, enzastaurin and ZM447439) and evaluated the modulation of pivotal pathways in drug activity and cancer cell proliferation. RESULTS: Vandetanib emerged as the compound with the most potent cytotoxic activity, which interacted synergistically with carboplatin and pemetrexed. Drug combinations blocked Akt phosphorylation and increased apoptosis. Vandetanib significantly downregulated epidermal growth factor receptor (EGFR)/Erk/Akt phosphorylation as well as E2F-1 mRNA and TS mRNA/protein levels. Moreover, pemetrexed decreased Akt phosphorylation and expression of DNA repair genes. Finally, most MPM samples displayed detectable levels of EGFR and TS, the variability of which could be used for patients' stratification in future trials with vandetanib-pemetrexed-carboplatin combination. CONCLUSION: Vandetanib markedly enhances pemetrexed-carboplatin activity against human MPM cells. Induction of apoptosis, modulation of EGFR/Akt/Erk phosphorylation and expression of key determinants for pemetrexed and carboplatin activity contribute to this synergistic interaction, and, together with the expression of these determinants in MPM samples, warrant further clinical investigation.

Study of apoptosis induction and deoxycytidine kinase/cytidine deaminase modulation in the synergistic interaction of a novel ceramide analog and gemcitabine in pancreatic cancer cells.

This study investigated the interaction between the novel ceramide analog AL6 and gemcitabine in MIA PaCa-2 and PANC-1 pancreatic cancer cell lines, harboring different polymorphic variants of the gemcitabine catabolism enzyme cytidine deaminase (CDA). AL6 dose-dependently inhibited cell growth, induced apoptosis and synergistically enhanced the cytotoxic activity of gemcitabine. Moreover, it triggered apoptosis, which was significantly enhanced by the combination, and increased the ratio between gene expression of the activating enzyme deoxycytidine kinase (dCK) and CDA, potentially favoring gemcitabine activity. In conclusion, AL6 displays synergistic cytotoxic activity, enhances apoptosis, and favorably modulates enzymes involved in gemcitabine metabolism, supporting future investigation of this combination in pancreatic cancer.

Inhibition of DNA topoisomerase I and growth inhibition of human cancer cell lines by an oleanane from Junellia aspera (Verbenaceae).

DNA topoisomerases and DNA polymerases are enzymes that play a crucial role in DNA metabolism events such as replication, transcription, recombination, and chromosome segregation during mitosis. Thus, DNA topoisomerases and DNA polymerases inhibitors could be expected to have antitumor effects. Naturally occurring triterpenoids isolated from Junellia aspera (Gillies & Hook; Moldenke) (Verbenaceae) were assayed for human DNA topoisomerase I and Taq DNA polymerase inhibitory activities. Maslinic acid (2) and its diacetyl derivative (7) showed human DNA topoisomerase I inhibitory activity with IC50 values in the range of 76-80 microM and growth inhibition against various human solid tumour cell lines with GI50 values in the range of 5-18 microM. The triterpene frames could be used for screening new inhibitors of the enzyme, and computer-simulated drug design using the frame and pocket structure of enzyme may in theory be a possible approach to develop new inhibitors.

Synthesis and antiproliferative activity of novel sugiol beta-amino alcohol analogs.

A series of beta-amino alcohol analogs of sugiol were synthesized in a straightforward manner. The in vitro antiproliferative activities were examined in the human solid tumor cell lines A2780, SW1573 and WiDr. The most potent analogs induced considerably growth inhibition in the range 1.5-6.7 microM. The results showed that beta-amino alcohol analogs are more potent than the parent compound. In addition, the derivatives with secondary amine fragments showed more active than those bearing tertiary amines.

Canine long-term bone marrow culture neutrophil production and functionality.

This in vitro study has been conducted to determine the optimal experimental conditions under which to produce canine neutrophils in long-term bone marrow cultures (LTBMC), establish functional parameters of neutrophils obtained from LTBMC and peripheral blood and to ascertain whether these cells display physiological similarities. Our aim is to provide an experimental model, enabling a correlation between hemopoietic injury and neutrophil functionality. The authors demonstrate for the first time that canine neutrophils grown in cultures are able to produce oxyradicals capable of killing bacterial products. Moreover, culture-grown neutrophils contain gelatinase granules, a marker of terminal neutrophil differentiation, and express a specific surface antigen. The results described in this article illustrate the development of a dynamic system that mimics physiological hemopoiesis.