Toxic interaction between narcotic analgesics and inhibitors of catechol-O-methyltransferase

Advanced cancer pain: the search for genetic factors correlated with interindividual variability in opioid requirement

AIM

To assess association between genetic variants and opioid requirement in cancer patients.

MATERIALS & METHODS

A prospective observational trial of 243 advanced cancer patients with inadequate analgesia treated by the palliative care team was analyzed for ABCB1, ARRB2, COMT, GCH1, IL1RN, KCNJ6, OPRM1, RHBDF2, SCN9A and Stat6 polymorphisms.

RESULTS

For patients carrying OPRM1 118AG/GG and COMT 472GG (Val158Val) or these genotypes alone, a significant higher median percentage dose increase was observed (95.2% [32.8-345]) compared with OPRM1 118AA and COMT 472GA/AA (158Met allele carriers; 48.5% [0-98.8]; p = 0.0016). No associations were found with morphine equivalent dose after consultation palliative care team or ketamine use.

CONCLUSION

Patients with the combined OPRM1 118AG/GG and COMT 472GG genotype required 50% higher dose increase for sufficient analgesia.

Transcriptional profiling of C57 and DBA strains of mice in the absence and presence of morphine

Background

The mouse C57BL/6 (C57) and DBA/2J (DBA) inbred strains differ substantially in many aspects of their response to drugs of abuse. The development of microarray analyses represents a genome-wide method for measuring differences across strains, focusing on expression differences. In the current study, we carried out microarray analysis in C57 and DBA mice in the nucleus accumbens of drug-naïve and morphine-treated animals.

Results

We identified mRNAs with altered expression between the two strains. We validated the mRNA expression changes of several such mRNAs, including Gnb1, which has been observed to be regulated by several drugs of abuse. In addition, we validated alterations in the enzyme activity of one mRNA product, catechol-O-methyltransferase (Comt). Data mining of expression and behavioral data indicates that both Gnb1 and Comt expression correlate with aspects of drug response in C57/DBA recombinant inbred strains. Pathway analysis was carried out to identify pathways showing significant alterations as a result of treatment and/or due to strain differences. These analyses identified axon guidance genes, particularly the semaphorins, as showing altered expression in the presence of morphine, and plasticity genes as showing altered expression across strains. Pathway analysis of genes showing strain by treatment interaction suggest that the phosphatidylinositol signaling pathway may represent an important difference between the strains as related to morphine exposure.

Conclusion

mRNAs with differing expression between the two strains could potentially contribute to strain-specific responses to drugs of abuse. One such mRNA is Comt and we hypothesize that altered expression of Comt may represent a potential mechanism for regulating the effect of, and response to, multiple substances of abuse. Similarly, a role for Gnb1 in responses to multiple drugs of abuse is supported by expression data from our study and from other studies. Finally, the data support a role for semaphorin signaling in morphine effects, and indicate that altered expression of genes involved in phosphatidylinositol signaling and plasticity might also affect the altered drug responses in the two strains.

Antiangiogenic activity of 4-O-methylgallic acid from Canavalia gladiata, a dietary legume

Development of nontoxic and biologically safe antiangiogenic agent has been highlighted as a promising way to treat angiogenesis related diseases including cancer. Herein, we isolated 4-O-methylgallic acid (4-OMGA) from the seed of Canavalia gladiata, a dietary legume, on the basis of the growth inhibitory activity for bovine aortic endothelial cells (BAECs). The compound potently inhibits endothelial cell invasion and tube formation stimulated with basic fibroblast growth factor (bFGF) at low micromolar concentrations where it shows no cytotoxicity to the cells. In addition, 4-OMGA inhibits vascular endothelial cell growth factor (VEGF) production under hypoxic condition and the production of reactive oxygen species (ROS) in the endothelial cells stimulated with VEGF. These results demonstrate that 4-OMGA is a compound having potential for an antiangiogenic agent.

Biological activity of tropolone

Tropolone (1). showed strong insecticidal activity on Tyrophagus putrescentiae and Dermatophagoides farinae. The insecticidal effect of 1 on both insects was stronger than that of hinokitiol (2, 4-isopropyltropolone: major component of Thujopsis dolabrata SIEB. et ZUCC. hondai MAKINO). The insecticidal activity of both compounds was higher than that of N,N-diethyl-m-toluamide (DEET), used as a positive control. Compound 1 had potent insecticidal activity against Coptotermes formosanus, although its activity was much lower than that of commercial chloropyrifos. Like 2, 1 showed the inhibitory activity toward metalloproteases such as carboxypeptidase A, collagenase and thermolysin and their inhibitory activities were much higher than that of 1,10-phenanthroline, used as a positive control. The inhibitory activity of 1 on carboxypeptidase A was especially high, its 50% inhibitory concentrations (IC(50)) being 2.73 x 10(-6) M. This inhibitory activity was as high as that of 2 (IC(50): 2.76 x 10(-6) M). Compound 1 inhibited the growth of seven kinds of plant-pathogenic fungi and their minimum inhibitory concentration (MIC) values were in the range of 6.0-50.0 microg/ml. In particular, 1 showed strong antifungal activity on Pythium aphanidermatum IFO-32440 (MIC: 6.0 microg/ml).