Identification of Galanin and Its Receptor GalR1 as Novel Determinants of Resistance to Chemotherapy and Potential Biomarkers in Colorectal Cancer

Purpose: A major factor limiting the effective clinical management of colorectal cancer (CRC) is resistance to chemotherapy. Therefore, the identification of novel, therapeutically targetable mediators of resistance is vital.Experimental design: We used a CRC disease-focused microarray platform to transcriptionally profile chemotherapy-responsive and nonresponsive pretreatment metastatic CRC liver biopsies and in vitro samples, both sensitive and resistant to clinically relevant chemotherapeutic drugs (5-FU and oxaliplatin). Pathway and gene set enrichment analyses identified candidate genes within key pathways mediating drug resistance. Functional RNAi screening identified regulators of drug resistance.

Results: Mitogen-activated protein kinase signaling, focal adhesion, cell cycle, insulin signaling, and apoptosis were identified as key pathways involved in mediating drug resistance. The G-protein-coupled receptor galanin receptor 1 (GalR1) was identified as a novel regulator of drug resistance. Notably, silencing either GalR1 or its ligand galanin induced apoptosis in drug-sensitive and resistant cell lines and synergistically enhanced the effects of chemotherapy. Mechanistically, GalR1/galanin silencing resulted in downregulation of the endogenous caspase-8 inhibitor FLIP(L), resulting in induction of caspase-8-dependent apoptosis. Galanin mRNA was found to be overexpressed in colorectal tumors, and importantly, high galanin expression correlated with poor disease-free survival of patients with early-stage CRC.

Conclusion: This study shows the power of systems biology approaches to identify key pathways and genes that are functionally involved in mediating chemotherapy resistance. Moreover, we have identified a novel role for the GalR1/galanin receptor-ligand axis in chemoresistance, providing evidence to support its further evaluation as a potential therapeutic target and biomarker in CRC. Clin Cancer Res; 18(19); 5412–26. © 2012 AACR.

Differences in the diagnostic yield of upper gastrointestinal endoscopy in dyspeptic patients receiving proton-pump inhibitors and H2-receptor antagonists

Patients attending for diagnostic oesophagogastroduodenoscopy (OGD) for dyspeptic symptoms are often receiving acid-suppression therapy that has not been discontinued prior to endoscopy, and this may reduce the diagnostic yield of endoscopy. The aim of this study was to compare the diagnostic yield of OGD in uncomplicated dyspepsia in patients receiving no medication, those receiving acid-suppression therapy, and those receiving nonsteroidal anti-inflammatory drugs (NSAIDs) at the time of endoscopy.

Patients on H2-receptor antagonists--are we investigating them?

A survey was made of patients receiving H2-receptor antagonists in a group practice serving 8600 patients. Two hundred and twelve patients (2%) who had received at least one prescription for H2 antagonists in a 12 month period were identified. When compared with the practice population, men and patients over 50 years old were more likely to be taking these drugs (P less than 0.01 and P less than 0.001, respectively). One hundred and fifty-seven patients (74%) were investigated before commencing therapy; 114 (73%) of these patients were investigated via the hospital outpatient department, despite the general practitioners having full open access to barium meals. Only 23 (15%) of the patients investigated were found to have no active pathology. Twenty-nine (14%) of the 212 study patients had received one or more gastrointestinal investigations in the 18 months subsequent to starting H2-antagonist therapy. Twenty-five of these patients had also received an investigation before starting therapy. One hundred and eleven patients (52%) had had their H2 antagonist therapy initiated by their general practitioner.

A computerized audit of non-steroidal anti-inflammatory drug prescribing in general practice

The two group practices based in a city health centre decided to prescribe non-steroidal anti-inflammatory drugs in generic form from an agreed date. The practices' computer was used to identify the number of repeat prescriptions being issued for this group of drugs and to monitor the effectiveness of the changeover. Although both practices showed a marked increase in the level of generic prescribing there was considerable interpractice variation. Generic prescribing for one practice increased from 4% to 64% and for the other from 1% to 38% of repeat prescriptions issued for non-steroidal anti-inflammatory drugs over the study period. The reasons for this variation, the advantages of computerized audit and the problems associated with this self-imposed audit are discussed.

Repeat prescribing of non-steroidal anti-inflammatory drugs excluding aspirin:how careful are we?

About 5% of all National Health Service prescriptions in Britain and a quarter of reports of suspected adverse reactions are accounted for by non-steroidal anti-inflammatory drugs. Their prescription was investigated in two computerised group practices serving 11850 patients. Altogether 198 patients receiving repeat prescriptions of non-steroidal anti-inflammatory drugs were identified and relevant clinical details extracted from their notes. Of these patients, 119 were over 65 years old; 172 were receiving one of six different non-steroidal anti-inflammatory drugs; and 76 were taking drugs that can interact with non-steroidal anti-inflammatory drugs. Ninety one patients had one or more medical conditions that may be aggravated by non-steroidal anti-inflammatory drugs, and 36 had experienced side effects important enough for their treatment to be changed. A questionnaire to assess opinions and knowledge of non-steroidal anti-inflammatory drugs was given to 42 general practitioners and 26 rheumatologists. Although the two groups showed a comparable knowledge of the properties and costs of non-steroidal anti-inflammatory drugs, they differed significantly in their views on the circumstances under which these drugs should be used. Clear guidelines on the prescription of these drugs would indicate when careful monitoring is essential for patients to benefit from them safely.

Risk of Alzheimer's disease is associated with a very low-density lipoprotein receptor genotype in Northern Ireland

The epsilon-4 allele of apolipoprotein E (APOE) is associated with increased risk of Alzheimer's disease (AD), but the pathogenic mechanism is unknown. The 5-repeat allele of a CGG repeat polymorphism in the 5' untranslated region of the very low-density lipoprotein receptor (VLDL-R) gene, a receptor for apoE, has been found to be associated with increased risk of AD in a Japanese population. Other groups have been unable to replicate this in American Caucasian populations. A case-control study utilizing a clinically well-defined group of late-onset AD patients (n = 108) and age- and sex-matched control subjects (n = 108) from Northern Ireland was performed to test this association in a relatively homogeneous population. The 9,9 genotype of the VLDL-R was found to be significantly increased in patients compared to controls (P = 0.003; Pcorr = 0.035), leading to an increased risk of AD to subjects with this genotype (OR = 3.9; 95% CI, 1.52-11.25). In contrast to results from the Japanese study, the 5-repeat allele was found to be significantly reduced in the patient group when compared to controls (P = 0.008; Pcorr = 0.047). The results from this study suggest that individuals who have the 9,9 genotype of the VLDL-R gene are at increased risk of AD in Northern Ireland.

A whole-genome massively parallel sequencing analysis of BRCA1 mutant oestrogen receptor-negative and -positive breast cancers

BRCA1 encodes a tumour suppressor protein that plays pivotal roles in homologous recombination (HR) DNA repair, cell-cycle checkpoints, and transcriptional regulation. BRCA1 germline mutations confer a high risk of early-onset breast and ovarian cancer. In more than 80% of cases, tumours arising in BRCA1 germline mutation carriers are oestrogen receptor (ER)-negative; however, up to 15% are ER-positive. It has been suggested that BRCA1 ER-positive breast cancers constitute sporadic cancers arising in the context of a BRCA1 germline mutation rather than being causally related to BRCA1 loss-of-function. Whole-genome massively parallel sequencing of ER-positive and ER-negative BRCA1 breast cancers, and their respective germline DNAs, was used to characterize the genetic landscape of BRCA1 cancers at base-pair resolution. Only BRCA1 germline mutations, somatic loss of the wild-type allele, and TP53 somatic mutations were recurrently found in the index cases. BRCA1 breast cancers displayed a mutational signature consistent with that caused by lack of HR DNA repair in both ER-positive and ER-negative cases. Sequencing analysis of independent cohorts of hereditary BRCA1 and sporadic non-BRCA1 breast cancers for the presence of recurrent pathogenic mutations and/or homozygous deletions found in the index cases revealed that DAPK3, TMEM135, KIAA1797, PDE4D, and GATA4 are potential additional drivers of breast cancers. This study demonstrates that BRCA1 pathogenic germline mutations coupled with somatic loss of the wild-type allele are not sufficient for hereditary breast cancers to display an ER-negative phenotype, and has led to the identification of three potential novel breast cancer genes (ie DAPK3, TMEM135, and GATA4).

Transient receptor potential ankyrin 1 channel localized to non-neuronal airway cells promotes non-neurogenic inflammation

The transient receptor potential ankyrin 1 (TRPA1) channel, localized to airway sensory nerves, has been proposed to mediate airway inflammation evoked by allergen and cigarette smoke (CS) in rodents, via a neurogenic mechanism. However the limited clinical evidence for the role of neurogenic inflammation in asthma or chronic obstructive pulmonary disease raises an alternative possibility that airway inflammation is promoted by non-neuronal TRPA1.

Toxicity of non-steroidal anti-inflammatory drugs to Gyps vultures:a new threat from ketoprofen

Three Gyps vulture species are on the brink of extinction in South Asia owing to the veterinary non-steroidal anti-inflammatory drug (NSAID) diclofenac. Carcasses of domesticated ungulates are the main food source for Asia's vultures and birds die from kidney failure after consuming diclofenac-contaminated tissues. Here, we report on the safety testing of the NSAID ketoprofen, which was not reported to cause mortality in clinical treatment of scavenging birds and is rapidly eliminated from livestock tissues. Safety testing was undertaken using captive non-releasable Cape griffon vultures (Gyps coprotheres) and wild-caught African white-backed vultures (G. africanus), both previously identified as susceptible to diclofenac and suitable surrogates. Ketoprofen doses ranged from 0.5 to 5 mg kg(-1) vulture body weight, based upon recommended veterinary guidelines and maximum levels of exposure for wild vultures (estimated as 1.54 mg kg(-1)). Doses were administered by oral gavage or through feeding tissues from cattle dosed with ketoprofen at 6 mg kg(-1) cattle body weight, before slaughter. Mortalities occurred at dose levels of 1.5 and 5 mg kg(-1) vulture body weight (within the range recommended for clinical treatment) with the same clinical signs as observed for diclofenac. Surveys of livestock carcasses in India indicate that toxic levels of residual ketoprofen are already present in vulture food supplies. Consequently, we strongly recommend that ketoprofen is not used for veterinary treatment of livestock in Asia and in other regions of the world where vultures access livestock carcasses. The only alternative to diclofenac that should be promoted as safe for vultures is the NSAID meloxicam.

Apparent tolerance of turkey vultures (Cathartes aura) to the non-steroidal anti-inflammatory drug diclofenac

The nonsteroidal anti-inflammatory drug diclofenac is extremely toxic to Old World Gyps vultures (median lethal dose -0.1-0.2 mg/kg), evoking visceral gout, renal necrosis, and mortality within a few days of exposure. Unintentional secondary poisoning of vultures that fed upon carcasses of diclofenac-treated livestock decimated populations in the Indian subcontinent. Because of the widespread use of diclofenac and other cyclooxygenase-2 inhibiting drugs, a toxicological study was undertaken in turkey vultures (Cathartes aura) as an initial step in examining sensitivity of New World scavenging birds. Two trials were conducted entailing oral gavage of diclofenac at doses ranging from 0.08 to 25 mg/kg body weight. Birds were observed for 7 d, blood samples were collected for plasma chemistry (predose and 12, 24, and 48 h and 7 d postdose), and select individuals were necropsied. Diclofenac failed to evoke overt signs of toxicity, visceral gout, renal necrosis, or elevate plasma uric acid at concentrations greater than 100 times the estimated median lethal dose reported for Gyps vultures. For turkey vultures receiving 8 or 25 mg/kg, the plasma half-life of diclofenac was estimated to be 6 h, and it was apparently cleared after several days as no residues were detectable in liver or kidney at necropsy. Differential sensitivity among avian species is a hallmark of cyclooxygenase-2 inhibitors, and despite the tolerance of turkey vultures to diclofenac, additional studies in related scavenging species seem warranted.