Current Pharmacogenomics and Personalized Medicine (Formerly Current Pharmacogenomics) - Volume 11, Issue 1, 2013

The generation of genetically altered mice for research is invaluable for investigations into the underlying mechanisms of common complex diseases such as cancer as well as for therapeutic studies. The correct identification of the genotype of each mouse is therefore essential. Genotyping is routinely performed by using blood, tail or ear tissue; however, this can cause pain or discomfort to the animal and nor is amenable to scale up for high-throughput sampling and analyses. Genotyping from saliva, hair and rectal cells is less invasive, but still requires the restraint of the animal. In contrast, collection of stool samples for DNA isolation is non-invasive as well as repeatable and time efficient, with recent studies showing it to be as accurate as the alternative methods. Fecal DNA genotyping therefore provides an attractive technique for non-invasive genotyping. This feature article examines and synthesizes the recent advances in fecal genotyping with a view to mouse models for nutrigenomics cancer chemoprevention studies specifically, and personalized medicine more broadly.

Multiple single nucleotide polymorphisms (SNPs) associated with prostate cancer (PC) have been reported in statistically robust studies in the past but these require an in-depth mechanistic understanding with respect to the biological pathways leading to disease. The current study was carried out to examine the PC and benign urology disease risk associations with lifestyle, demographic and genetic factors in a group of men between the ages 40-81 years from Auckland, New Zealand. The data presented herein support a significant positive association of PC risk with tobacco smoking, and a negative association with alcohol intake. The BMI was not associated with disease risk. The SRD5A2 rs632148 G allele was associated with PC compared to those with benign urology disease, after adjustments were made for the confounding variables. The Gleason score as well as disease aggressiveness of the PC group showed no association with lifestyle, demographic factors or the SNPs studied. The levels of prostate-specific antigen (PSA) significantly increased with age, smoking status and BMI, and decreased with alcohol consumption. The AKR1C3 rs12529 G allele was significantly associated with lower PSA levels in PC and benign urology disease groups compared to healthy controls. The G allele of the SRD5A2 rs632148 SNP has shown a significant interaction with PSA and a higher Gleason score outcome. Taken together, these findings show the utility of these gene variants and patient lifestyle history, together with the diagnostic serum PSA levels, to collectively enhance the understanding of the clinical-pathological variables of PC. Such information will support the selection of more personalised treatment options for this disease greatly impacting public health.

Acquired resistance to trastuzumab is a clinical problem in the treatment of HER2-over-expressing metastatic breast cancer. Importantly, an earlier report suggested that high body mass index was associated with reduced overall survival and reduced time to progression in patients with early stage or metastatic HER2-positive breast cancer treated with trastuzumab. Adipocyte-secreted factors may stimulate growth of HER2-positive cancers, blocking the growth inhibitory action of trastuzumab. Leptin and growth differentiation factor 15 (GDF15) are two adipocytokines that have been reported to stimulate HER2-PI3K signaling. We previously showed that cells with acquired trastuzumab resistance express increased levels of GDF15, and that GDF15 knockdown restores sensitivity to trastuzumab. The objective of the current study was to identify potential molecular mechanisms by which adipocytes stimulate resistance to trastuzumab in HER2-over-expressing breast cancer cell lines. Cells were cultured in complete media or conditioned media from differentiated adipocytes (CM). Cell viability of trastuzumab-treated cells was examined under anchorage-dependent and - independent conditions. Phosphorylation of Akt was assessed by Western blotting, and response to trastuzumab was reassessed upon treatment with the PI3K inhibitor LY294002 or after transfection with kinase-dead Akt. We report that CM significantly reduced trastuzumab-mediated growth inhibition of HER2-positive cells, and stimulated rapid phosphorylation of Akt. Pharmacologic or genetic inhibition of PI3K overcame CM-mediated trastuzumab resistance. Leptin and GDF15 were both measured in CM, but only GDF15 conferred resistance to trastuzumab. Leptin, on the other hand, abrogated sensitivity to lapatinib but not trastuzumab. Our observations suggest that adipocyte-secreted factors such as GDF15 stimulates PI3K signaling, resulting in reduced response to trastuzumab. The utility of adipocytokines as predictors of drug resistance and approaches to mitigate the cancer-promoting effects of adipocyte-secreted factors should be further examined. Our work supports additional investigation into GDF15 as a potential biomarker of trastuzumab resistance, and development of approaches to therapeutically target GDF15 in HER2-positive breast cancers that have progressed on trastuzumab.

Interstitial fluid, obtained by gentle centrifugation of the renal biopsy specimen, is highly enriched in elements directly secreted by the kidney tissue and is suitable for proteomic analysis. Here we describe the first clinical application of renal interstitial fluid analysis in a subset of samples obtained from patients affected by idiopathic membranous nephropathy. We included in the study fifty-one patients with different pathologic diagnoses. We identified the proteomic pattern of idiopathic membranous nephropathy with mass spectrometry analysis by comparing these samples with two controls: normal kidney and IgA nephropathy. Proteomic results were validated by immunofluorescence analysis of renal tissues and Western blot of serum, urines and podocyte cell cultures. We observed an increased expression of PDZ and LIM domain protein 5 (PDLI5) and LIM domain binding protein 3 (LDB3) providing first evidence of the differential expression of these LIM domain-related proteins in kidney and urines of patients with idiopathic membranous nephropathy. Interstitial fluid can be considered a valuable biological fluid in the discovery phase of biomarkers. In order to validate its clinical use, it is pivotal to assess the availability of the biomarkers in ‘usual’ samples: blood and/or urine. PDLI5 and LDB3 share a common LIM domain suggesting a possible role in the cytoskeleton organization and they appear upregulated in glomeruli of patients affected by idiopathic membranous nephropathy. Furthermore the two proteins become highly abundant in the urine of patients affected by idiopathic membranous nephropathy. In conclusion, our approach may be considered a novel method for identifying candidate biomarkers for patients suffering from membranous nephropathy and other glomerulonephrites.

Glycosylation, linking the glycan chains to protein or lipid, is the most common and complex post-translational modifications of proteins. One of the important functions of glycoprotein is to maintain the ordered social life of each cell in multicellular organisms. Glycosylation is sensitive to the biochemical environment leading to the alteration of glycan chains under the physiological condition and specific diseases such as cancer. Cancer and other lethal diseases cannot be diagnosed at early stage due to classic biomarker's low sensitivity and specificity. Recently, the development of glycan profiling technologies has offered great promises for understanding the complex glycan structures and has increased interest in applying this technology for cancer studies. In this regard, to identify the glycans as the potential biomarkers of cancer has become an important direction for clinical cancer diagnosis. This paper summarizes the current research on validating and developing of the glycans as new cancer biomarkers and the nascent field of glycomics

Polymorphisms in genes involved in pain processing contribute to variation in pain sensitivity and clinical response to opioid therapy. This paper reviews the evidence on how opioid receptor, mu 1 (OPRM1) polymorphisms might influence pain sensitivity, opioid dose requirements and opioid-related effects such as analgesia and side effects. For example, it is shown that (1) individuals with AG and GG genotypes (118G variant allele carriers) exhibit lower sensitivity to pressure pain (higher pressure pain thresholds) compared with wild-type subjects (AA genotype or 118A allele carriers), and (2)individuals with GG genotypes require higher opioid doses compared with those who are AA or AG genotypes. The pain scores increase with increasing number of 118G alleles. Patients with the AA genotype have a greater analgesic effect than those with 118G allele (AG or GG genotypes). Additionally, the presence of 118G allele is associated with a reduced risk of nausea in spite of a higher morphine use, lower vomiting episodes and lower severity score for pruritus. Notably, even though many studies investigated a possible role of the OPRM1 polymorphisms in the risk for altered pain sensitivity, opioid dose and analgesia and opioid-related side effects in patients with pain, the results are conflicting. More studies to characterize the effects of other candidate genes and the combined effects of multiple genes, demography and clinical variables in predicting the clinical response and opioid-related side effects are required and these should involve larger numbers of patients in different population types.

The glial cell line-derived neurotrophic factor (GDNF) family, which includes GDNF, artemin, persephin, and neurturin, rests within the transforming growth factor-beta superfamily. GDNF family members play a crucial role in the development of peripheral autonomic and sensory neurons. Recent studies on the impact of GDNF on posttraumatic nerve regeneration and the treatment of neuropathic pain found that GDNF reversed the posttraumatic changes. This paper focuses on different pharmacological effects of GDNFs that are currently under examination enabled by pharmacogenomic and pharmacoproteomic studies. From these lessons learned, it seems clear that GDNF is involved in the mechanism of action of drugs that improve neurodegenerative diseases and drug abuse, including alcohol. Although it is difficult to postulate precisely GDNF pathway-specific drugs at this time, identification of genes or proteins that are specifically regulated by GDNF in certain cellular phenotypes might improve the efficacy of neurodegenerative disease therapies. Additionally, the possibility of fine-tuning GDNF expression in specific brain sites suffering from neurotrophic factor malfunction might allow refinement of the personalized strategies used to fight neuronal disorders.