Efficacy and Safety of Prucalopride in Patients with Chronic Noncancer Pain Suffering from Opioid-Induced Constipation

Opioid-induced constipation (OIC) has negative effects on quality of life (QOL). Prucalopride is a new, selective 5-HT4 agonist and enterokinetic with strong clinical data in chronic constipation. This study investigated the efficacy, safety, and tolerability of prucalopride in patients with noncancer pain and OIC. A phase II, double-blind, placebo-controlled study of 196 patients randomized to placebo (n = 66), prucalopride 2 mg (n = 66) or 4 mg (n = 64), for 4 weeks, was carried out. The primary endpoint was the proportion of patients with increase from baseline of a parts per thousand yen1 spontaneous complete bowel movement (SCBM)/week. Secondary endpoints [proportion of patients with a parts per thousand yen3 SCBM/week, weekly frequency of (SC)BM, severity of constipation, and efficacy of treatment], adverse events (AEs), and safety parameters were also monitored. More patients had an increase from baseline of a parts per thousand yen1 SCBM per week (weeks 1-4) in the prucalopride groups [35.9% (2 mg) and 40.3% (4 mg)] versus placebo (23.4%), reaching statistical significance in week 1. Over weeks 1-4, more patients in the prucalopride groups achieved an average of a parts per thousand yen3 SBM per week versus placebo (60.7% and 69.0% versus 43.3%), reaching significance at week 1. Prucalopride 4 mg significantly improved patient-rated severity of constipation and effectiveness of treatment versus placebo. Patient Assessment of Constipation-Symptom (PAC-SYM) total scores and Patient Assessment of Constipation-Quality of Life (PAC-QOL) total and satisfaction subscale scores were improved. The most common AEs were abdominal pain and nausea. There were no clinically relevant differences between groups in vital signs, laboratory measures or electrocardiogram parameters. In this population with OIC, prucalopride improved bowel function and was safe and well tolerated

Protein kinase D : downstream effectors and role in apoptosis

Reversible protein phosphorylation is a universal mechanism that all cells use to respond to extracellular signals, and to regulate physiological processes. Approximately one third of all cellular proteins are being phosphorylated. This post-translational modification is intricately regulated by the activity of protein kinases and protein phosphatases. Protein kinase D is a Ser/Thr protein kinase which has been implicated in many biological processes like vesicle trafficking, apoptosis, proliferation, adhesion and migration. However, only few of its physiological substrates are known. To better position PKD in the ever expanding web of signal transduction, we have studied signals that are upstream as well as downstream of PKD. During the course of this study, we have been able to show that PKD1 is cleaved by a caspase-dependent mechanism in doxorubicin-treated cells. This cleavage causes activation of PKD1 and the resulting fragments lead to a sensitization of the cells for apoptosis induced by genotoxic drugs. We postulate that full length PKD1 has a protective role which is converted to a pro-apoptotic function when cells are treated with DNA-damaging agents. Elucidating signals downstream of PKD has been hampered by the fact that few PKD substrates are known, and no specific PKD-inhibitor is available. By implementing a computational method for protein kinase substrate identification (Scansite 2.0), we were able to identify two physiological PKD substrates: Rhotekin and CREB. Rhotekin is a fairly unknown protein, which is phosphorylated in vitro and in vivo by PKD1 and PKD2 at Ser435. Initial results have indicated that phosphorylation of Rhotekin at this site could be an important regulatory event in the gastrin-induced migration of gastric cancer cells. CREB is a transcription factor which is regulated by phosphorylation through many protein kinases. We could show that CREB is phosphorylated in vitro and in vivo by PKD at Ser133, the main regulatory phosphorylation site in CREB. Moreover, constitutive active PKD1 was shown to co-immunoprecipitate with CREB. The phosphorylation of Ser133 results in an increased transactivation potential of CREB and induces the expression of the CREB-dependent gene Nur77. These results point to a dual role for PKD in regulating the transcription of Nur77: PKD-mediated phosphorylation and nuclear export of HDAC7 leads to the derepression ofstatus: publishe

Protein kinase D: a family affair

The protein kinase D family of enzymes consists of three isoforms: PKD1/PKCmu PKD2 and PKD3/PKCnu. They all share a similar architecture with regulatory sub-domains that play specific roles in the activation, translocation and function of the enzymes. The PKD enzymes have recently been implicated in very diverse cellular functions, including Golgi organization and plasma membrane directed transport, metastasis, immune responses, apoptosis and cell proliferatio

An enzyme-linked immunosorbent assay for protein kinase D activity using phosphorylation site-specific antibodies

The protein kinase D (PKD) family is a novel group of kinases that are involved in the regulation of cell proliferation and apoptosis, and several other physiological processes. Hence, these enzymes are attractive targets for pharmacological intervention, but no specific PKD inhibitors are known. With this in mind, we have developed a high-throughput, non-radioactive enzyme-linked immunosorbent assay (ELISA) method to monitor the PKD activity with myelin basic protein (MBP) as substrate. We determined that MBP is phosphorylated by PKD on Ser-160 and that this phosphorylation can be quantified in ELISAs, by the use of phosphorylation site-specific antibodies. Antibodies were developed that are highly specific for the MBP peptide sequence surrounding the phosphorylated Ser-160. We show that our high-throughput kinase assay is useful not only for determining the cellular PKD activity but also to screen for PKD-inhibitory compounds. Our ELISA has advantages over the current radioisotope kinase assay in terms of simplicity and environmental safet