Decytabine enhances cytotoxicity induced by oxaliplatin and 5-fluorouracil in the colorectal cancer cell line Colo-205

Background

DNA methylation is an epigenetic phenomenon known to play an important role in the development of cancers, including colorectal cancer (CRC). Aberrant methylation of promoter regions of genes is potentially reversible, and if methylation is important for cancer survival, demethylation should do the opposite. To test this we have addressed the hypothesis that DNA methyltransferase inhibitors (DNMTi), decytabine and zebularine, potentiate inhibitory effects of classical anti-CRC cytostatics, oxaliplatin and 5-fluorouracil (5-FU), on survival of CRC cells in vitro.

Results

Isobole and median effect analysis revealed that decytabine shows potent synergistic interaction with oxaliplatin and 5-FU and that this is probably not the class effect of DNMTi as zebularine shows strong antagonistic interaction with oxaliplatin. The synergistic combination treatment was also applied to the cultures to investigate their mechanisms of action. We have shown that combinations of decytabine with cytostatics produced dose-dependent growth inhibition and treatment-induced apoptosis.

Conclusion

The observed synergism between decytabine and cytostatics is most probably related to the augmented apoptotic signal and allowed for significant (both biologically and statistically) reduction of the cytotoxic doses of cytostatics used.

Patents and ethics: is it possible to be balanced?

In this presentation, principles of ethics are confronted with the desire of the inventor to make a profit. To this end the presentation is focused on patent protection. Patents should guarantee the return of an inventor's investment and profit and, on the other side, ensure availability--by patent disclosure--of the invention for the society when the patent terminates. Recent patent applications made by inventors are infringing this principle and societies are paying an unexpected price for these practices. Patent claims are too broad and disclosures too poor. Extreme examples will be discussed.

Clinical trials: active control vs placebo--what is ethical?

The quest for effective medicines is very old. In modern times two important tools have been developed to evaluate efficacy of drugs, superiority and non-inferiority types of clinical trials. The former tests the null hypothesis of micro (the difference between a tested drug and comparator) < or = 0 against micro > 0; the latter tests the null hypothesis of micro < or = - delta against, micro > - delta, where delta is the clinical difference from the comparator. In a superiority trial, a new drug is tested against a placebo; in a non-inferiority trial, a new drug is tested against active treatment. In this paper, arguments are presented to show that a superiority trial against a placebo is scientifically sound but ethically unacceptable, whereas a non-inferiority trial against active treatment is ethically sound but scientifically not reliable. Switching from a superiority type of trial with placebo to a non-inferiority trial with an active-control--following the latest revision of Declaration of Helsinki--is in practice switching from the violation of the uncertainty principle to uncertainty of results. Given human and financial resources, it appears an academic question as to which is more unethical: to violate patients' rights or to produce results without scientific value. All presented considerations lead to the conclusion that the use of a superiority trial of design with an active control instead of placebo will satisfy scientific needs, expectation of patients, and the ancient quest for effective medicines. In the era of Good (Clinical, Laboratory, Manufacture) Practice, the attention of those performing clinical trials is focused on the procedure, not always on its essence. However even the excellent performance of a trial which is not worth doing is fruitless.

Anti-angiogenic and apoptotic effects of metabolites of sulindac on chick embryo chorioallantoic membrane

Sulindac and other nonsteroidal anti-inflammatory drugs (NSAIDs), in addition to anti-inflammatory properties, express preventive activity against colon cancer. This antineoplastic effect may result from the suppression of polyp development in patients with familial adenomatous polyposis. However, despite intense investigations the exact mechanism for sulindac protective effect is not fully elucidated. Angiogenesis, the process of new blood vessel formation, is required to support tumor growth and may be partially involved in the transformation of polyps into tumor. Therefore, we tested the hypothesis whether sulindac might inhibit angiogenesis. The effects of sulindac metabolites, sulindac sulfide and sulindac sulfone, on vascular development were evaluated using the chick embryo chorioallantoic membrane (CAM) assay in vivo. The angiogenic response was quantitated by several methods including direct stereomicroscopic observation, measurements of hemoglobin content and DNA synthesis whereas quantitation of apoptosis was based on determinations of caspase-3 activity, caspase-3 and bax protein expression, and nuclear DNA fragmentation. Our results indicated that both sulindac metabolites were equally effective in inhibition of new blood vessel formation in CAM during chick embryo development. Moreover, both metabolites of sulindac induced the process of apoptosis parallelly to the inhibition of angiogenesis.

Plasma beta-thromboglobulin in acute myocardial infarction with ventricular arrhythmias

Patients with myocardial infarction, complicated by ventricular arrhythmias (Lown grade greater than or equal to 2), had higher (p less than 0.05) plasma beta-thromboglobulin level than that found in patients with uncomplicated infarction. This indicates higher platelet activation in the former group than in the latter. Such data provide rationale for clinical trial of antiplatelet drugs in cases of myocardial infarction complicated by severe arrhythmias.

Release of prostacyclin (PGI2) by the layers of corpus of rat stomach

Release of PGI2 by slices of muscularis and mucosa layers of rat corpus stomach was investigated. An anti-aggregatory substance that was released by slices of muscularis was identified as PGI2 in various bioassay systems including anti-serum against PGI2 as well as by stimulation of its generation with AA or PGH2 and by inhibition of this generation with indomethacin or tranylcypromine, respectively. PGI2 was the major PGs released from slices of muscularis. The release of PGI2 from muscularis surpasses a similar release of PGI2 from mucosa by a factor of 10. On the other hand, degradation of exogenous PGI2 was 4 times faster by mucosa than by muscularis slices. Our conclusion is that in the stomach corpus wall of rats, muscularis is the main source of PGI2, which may play a role in regulation of mucosal blood flow.

Body temperature of rats after prostaglandins E2 and F2 alpha and their precursor

Prostaglandins E2 and F2 alpha and arachidonic acid were injected into various brain structures outside the hypothalamus in rats. The body temperature rise induced by PGE2, but not by PGF2 alpha or arachidonic acid, was probably due to its diffusion or transport into the hypothalamus. Comparison of the latencies of the hyperthermic response to PGE2, PGF2 alpha, and arachidonic acid revealed that PGE2 was the most rapidly acting agent in structures located close to the hypothalamus. In contrast, arachidonic acid acted most rapidly after administration into the nucleus reticularis pontis caudalis.

Lungs as a generator of prostacyclin--hypothesis on physiological significance

In vivo anti-platelet de-aggregatory activity of exogenous prostacyclin is enhanced after its passage through the pulmonary circulation of anaesthetized cats, probably because of a concomitant generation of endogenous prostacyclin by the lungs. Evidence is also presented that perfused lungs of guinea pigs and rats spontaneously release considerable amounts of prostacyclin. It is therefore postulated that a continuous biosynthesis of prostacyclin by pulmonary endothelium is a general physiological phenomenon, while the generation of thromboxane A2 by lungs occurs in response to pathological stimuli. Coronary and cerebral arteries are supposed to benefit from this hormonal function of the lungs.