Recent Structure-Activity Studies of the Peptide Hormone Urotensin-II, a Potent Vasoconstrictor

Targeted Nanoparticles: the Smart Way for the Treatment of Colorectal Cancer

Colorectal cancer (CRC) is a widespread cancer that starts in the digestive tract. It is the third most common cause of cancer deaths around the world. The World Health Organization (WHO) estimates an expected death toll of over 1 million cases annually. The limited therapeutic options as well as the drawbacks of the existing therapies necessitate the development of non-classic treatment approaches. Nanotechnology has led the evolution of valuable drug delivery systems thanks to their ability to control drug release and precisely target a wide variety of cancers. This has also been extended to the treatment of CRC. Herein, we shed light on the pertinent research that has been performed on the potential applications of nanoparticles in the treatment of CRC. The various types of nanoparticles in addition to their properties, applications, targeting approaches, merits, and demerits are discussed. Furthermore, innovative therapies for CRC, including gene therapies and immunotherapies, are also highlighted. Eventually, the research gaps, the clinical potential of such delivery systems, and a future outlook on their development are inspired.

The urotensin-II receptor: A marker for staging and steroid outcome prediction in ulcerative colitis

BACKGROUND

Urotensin-II receptor- (UTR) related pathway exerts a key-role in promoting inflammation. The aim was to assess the relationship between UTR expression and clinical, endoscopic and biochemical severity of ulcerative colitis (UC), exploring its predictivity of intravenous (iv) steroid administration therapeutic outcome.

METHODS

One-hundred patients with first diagnosis of UC and 44 healthy subjects were enrolled. UTR expression was assessed by qPCR, Western Blot (WB) and immunohistochemistry (IHC). Clinical, endoscopic and histological activity of UC were evaluated by using Truelove and Witts (T&W) severity index, Mayo Endoscopic Score (MES), and Truelove and Richards Index (TRI). The partial and full Mayo scores (PMS and FMS) were assessed to stage the disease.

RESULTS

The UTR expression, resulted higher in the lesioned mucosa of UC patients in comparison to healthy subjects (p < .0001 all). Direct relationship between UTR (mRNA and protein) expression and disease severity assessment (T&W, PMS, MES and TRI) was highlighted (p < .0001 all). UTR expression resulted also higher in the 72 patients requiring iv steroids administration compared to those who underwent alternative medications, (p < .0001). The 32 steroid-non-responders showed an increased UTR expression (WB, IHC and qPCR from lesioned mucosa), compared to 40 steroid-responders (p: .0002, .0001, p < .0001 respectively). The predictive role of UTR expression (p < .05) on the negative iv steroids administration therapeutic outcome was highlighted and ROC curves identified the thresholds expressing the better predictive performance.

CONCLUSIONS

UTR represents a promising inflammatory marker related to clinical, endoscopic, and histological disease activity as well as a predictive marker of steroid administration therapeutic outcome in the UC context.

Urotensin-II-Targeted Liposomes as a New Drug Delivery System towards Prostate and Colon Cancer Cells

Urotensin-II (UT-II) and its receptor (UTR) are involved in the occurrence of different epithelial cancers. In particular, UTR was found overexpressed on colon, bladder, and prostate cancer cells. The conjugation of ligands, able to specifically bind receptors that are overexpressed on cancer cells, to liposome surface represents an efficient active targeting strategy to enhance selectivity and efficiency of drug delivery systems. The aim of this study was to develop liposomes conjugated with UT-II (LipoUT) for efficient targeting of cancer cells that overexpress UTR. The liposomes had a mean diameter between 150 nm and 160 nm with a narrow size distribution (PI ≤ 0.1) and a doxo encapsulation efficiency of 96%. Moreover, the conjugation of UT-II to liposomes weakly reduced the zeta potential. We evaluated UTR expression on prostate (DU145, PC3, and LNCaP) and colon (WIDR and LoVo) cancer cells by FACS and western blotting analysis. UTR protein was expressed in all the tested cell lines; the level of expression was higher in WIDR, PC3, and LNCaP cells compared with LoVo and DU145. MTT cell viability assay showed that LipoUT-doxo was more active than Lipo-doxo on the growth inhibition of cells that overexpressed UTR (PC3, LNCaP, and WIDR) while in LoVo and DU145 cell lines, the activity was similar to or lower than that one of Lipo-doxo, respectively. Moreover, we found that cell uptake of Bodipy-labeled liposomes in PC3 and DU145 was higher for LipoUT than the not-armed counterparts but at higher extent in UTR overexpressing PC3 cells (about 2-fold higher), as evaluated by both confocal and FACS. In conclusion, the encapsulation of doxo in UT-II-targeted liposomes potentiated its delivery in UTR-overexpressing cells and could represent a new tool for the targeting of prostate and colon cancer.

Urotensin II receptor expression in patients with ulcerative colitis: a pilot study

BACKGROUND

Urotensin II (U-II) is a vasoactive peptide that interacts with a specific receptor named UTR. Recently, our group has demonstrated increased UTR expression in both human colon adenocarcinoma cell lines and adenomatous polyps, as well as in colon carcinoma samples if compared to healthy colon samples of the same patients. We also showed that an UTR agonist induced an increase in colon adenocarcinoma cell growth in vitro, whereas the UTR block with a specific antagonist caused an inhibition of their growth and an inhibition of about 50% of both motility and cell invasion. Ulcerative colitis (UC) is an inflammatory bowel disease (IBD) associated with an increased baseline risk for colon cancer compared with the general population, and this risk is mostly attributed to chronic inflammation and immune dysregulation. This risk increases along with the duration of the disease, as demonstrated by many studies. There are no UTR expression data related to UC, and we therefore evaluated UTR expression in ill colon biopsies and in healthy colon ones of patients with UC and colon biopsies of healthy patients.

METHODS

We enrolled, prior to informed consent, 11 patients (5 males and 6 females, age range 29-75 years, median age 52 years) with first UC diagnosis compared to 11 healthy controls (6 males and 5 females, age range 30-78 years, median age 55 years). We have therefore sampled inflammatory and healthy tissue in UC patients. We have also taken colic tissue samples in healthy subjects. Evaluation of receptor expression was performed by reverse transcription-polymerase chain reaction (RT-PCR), Western Blot analysis. The ANOVA Test (P<0.05) was used for statistical analysis.

RESULTS

We found: 1) increased expression of UTR in 11/11 UC patients with ill mucosa biopsies compared to healthy controls in RT-PCR and in Western Blot analysis; 2) increased UTR expression in 11/11 UC patients with ill colon biopsies compared to the results obtained from healthy colon biopsies of the same patients both in RT-PCR and in Western Blot analysis; 3) increased UTR expression in 9/11 UC patients healthy colon biopsy specimens compared to healthy controls.

CONCLUSIONS

UTR could be considered as an inflammatory UC disease marker because its expression is greater in the mucosa of ill colon than in the healthy colon of the same patients and compared to healthy controls.

Natural and synthetic peptides in the cardiovascular diseases: An update on diagnostic and therapeutic potentials

Several peptides play an important role in physiological and pathological conditions into the cardiovascular system. In addition to well-known vasoactive agents such as angiotensin II, endothelin, serotonin or natriuretic peptides, the vasoconstrictor Urotensin-II (Uro-II) and the vasodilators Urocortins (UCNs) and Adrenomedullin (AM) have been implicated in the control of vascular tone and blood pressure as well as in cardiovascular disease states including congestive heart failure, atherosclerosis, coronary artery disease, and pulmonary and systemic hypertension. Therefore these peptides, together with their receptors, become important therapeutic targets in cardiovascular diseases (CVDs). Circulating levels of these agents in the blood are markedly modified in patients with specific CVDs compared with those in healthy patients, becoming also potential biomarkers for these pathologies. This review will provide an overview of current knowledge about the physiological roles of Uro-II, UCN and AM in the cardiovascular system and their implications in cardiovascular diseases. It will further focus on the structural modifications carried out on original peptide sequences in the search of analogues with improved physiochemical properties as well as in the delivery methods. Finally, we have overviewed the possible application of these peptides and/or their precursors as biomarkers of CVDs.

Urotensin-II receptor is over-expressed in colon cancer cell lines and in colon carcinoma in humans

BACKGROUND

Urotensin (U)-II receptor (UTR) has been previously reported to be over-expressed in a number of tumours. Whether UTR-related pathway plays a role in colon carcinogenesis is unknown.

METHODS

We evaluated UTR protein and mRNA expression in human epithelial colon cancer cell lines and in normal colon tissue, adenomatous polyps and colon cancer. U-II protein expression was assessed in cancer cell lines. Moreover, we evaluated the effects of U-II(4-11) (an UTR agonist), antagonists and knockdown of UTR protein expression through a specific shRNA, on proliferation, invasion and motility of human colon cancer cells.

RESULTS

Cancer cell lines expressed U-II protein and UTR protein and mRNA. By immunohistochemistry, UTR was expressed in 5-30% of epithelial cells in 45 normal controls, in 30-48% in 21 adenomatous polyps and in 65-90% in 48 colon adenocarcinomas. UTR mRNA expression was increased by threefold in adenomatous polyps and eightfold in colon cancer, compared with normal colon. U-II(4-11) induced a 20-40% increase in cell growth while the blockade of the receptor with specific antagonists caused growth inhibition of 20-40%. Moreover, the knock down of UTR with a shRNA or the inhibition of UTR with the antagonist urantide induced an approximately 50% inhibition of both motility and invasion.

CONCLUSIONS

UTR appears to be involved in the regulation of colon cancer cell invasion and motility. These data suggest that UTR-related pathway may play a role in colon carcinogenesis and that UTR may function as a target for therapeutic intervention in colon cancer.

Urotensin II: lessons from comparative studies for general endocrinology

The importance of combining studies across vertebrates to provide insights into the functionality of hormone systems is considered, using recent advances in Urotensin II (UII) biology to illustrate this. The impact of genome analyses on understanding ligand and UII receptor (UT) structures is reviewed, noting their high conservation from fish to mammals. The early linkage of UII with fish osmoregulatory physiology drove our investigation of possible renal actions of UII in mammals. The kidney is a potential major source of UII in mammals and endogenous peptide appears to have tonal influence over renal excretion of water and electrolytes. Blockade of UII actions by administration of UT receptor antagonist, urantide, in anaesthetised rats, indicates that endogenous UII lowers renal filtration rates and excretion of water and ions. These effects are considered in relation to apparent association of UII with a number of human cardiovascular and renal disorders. Following up the sequencing of UT in mammals here we contrast the first fish UT sequences with those in other species. It is now evident that UT expression in fish osmoregulatory tissues, such as the gill and kidney, exhibits considerable plasticity in response to physiological challenge, providing an important component of the adaptive organismal responses. A number of areas of UII research, which will continue to benefit from moving questions between appropriate vertebrate groups, have been highlighted. These comparative approaches will yield improved understanding and further novel actions of this intriguing endocrine and paracrine system, so highly conserved across the vertebrate series.

Solution structure of urotensin-II receptor extracellular loop III and characterization of its interaction with urotensin-II

Urotensin-II (U-II) is a vasoactive hormone that acts through a G-protein-coupled receptor named UT. Recently, we have shown, using the surface plasmon resonance technology that human U-II (hU-II) interacts with the hUT(281-300) fragment, a segment containing the extracellular loop III (EC-III) and short extensions of the transmembrane domains VI and VII (TM-VI and TM-VII). To further investigate the interaction of UT receptor with U-II, we have determined the solution structure of hUT(281-300) by high-resolution NMR and molecular modeling and we have examined, also using NMR, the binding with hU-II at residue level. In the presence of dodecylphosphocholine micelles, hUT(281-300) exhibited a type III beta-turn (Q285-L288), followed by an -helical structure (A289-L299), the latter including a stretch of transmembrane helix VII. Upon addition of hU-II, significant chemical shift perturbations were observed for residues located just on the N-terminal side of the beta-turn (end of TM-VI/beginning of EC-III) and on one face of the -helix (end of EC-III/beginning of TM-VII). These data, in conjunction with intermolecular NOEs, suggest that the initiation site of EC-III, as well as the upstream portion of helix VII, would be involved in agonist binding and allow to propose points of interaction in the ligand-receptor complex.

Urotensin II and renal function in the rat

Urotensin II (UII) is a potent vasoactive hormone in mammals. However, despite its well-known effects on epithelial sodium transport in fish, little is known about its actions on the mammalian kidney. The aim of this study was to determine the effects of UII on renal function in the rat. Using standard clearance methods, the effects of rUII and the rat UII receptor (UT) antagonist, urantide, were studied. UII was measured in plasma and urine by radioimmunoassay. UII and UT were localized in the kidney by immunohistochemistry and mRNA expression quantified. Rat urinary [UII] was 1,650-fold higher than that in plasma. Immunoreactive-UII was localized to the proximal tubules, outer and inner medullary collecting ducts (IMCD); UT receptor was identified in glomerular arterioles, thin ascending limbs, and IMCD. UII and UT mRNA expression was greater in the medulla; expression was higher still in spontaneously hypertensive rats (SHRs) associated with raised plasma (UII). Injection of rUII induced reductions in glomerular filtration rate (GFR), urine flow, and sodium excretion. Urantide infusion resulted in increases in these variables. Endogenous UII appears to contribute to the regulation of GFR and renal sodium and water handling in the rat. While hemodynamic changes predominate, we cannot rule out the possibility of a direct tubular action of UII. Increased expression of UII and UT in the SHR suggests that UII plays a role in the pathophysiology of cardiovascular disease.

Design and Synthesis of Potent Cystine-Free Cyclic Hexapeptide Agonists at the Human Urotensin Receptor

[structure: see text] Cyclic hexapeptides, incorporating a dipeptide unit in place of the disulfide bond found in urotensin, were prepared and screened at the human urotensin receptor. The bridging dipeptide unit was found to influence dramatically the affinity for the urotensin receptor. Alanyl-N-methylalanyl and alanylprolyl dipeptide bridges failed to afford active ligands, while the alanyl-alanyl unit yielded a ligand with submicromolar affinity for the urotensin receptor. Further development led to a hexapeptide agonist with nanomolar affinity (2.8 nM).

Novel Potent and Efficacious Nonpeptidic Urotensin II Receptor Agonists

Six different series of nonpeptidic urotensin II receptor agonists have been synthesized and evaluated for their agonistic activity in a cell-based assay (R-SAT). The compounds are ring-opened analogues of the isochromanone-based agonist AC-7954 with different functionalities constituting the linker between the two aromatic ring moieties. Several of the compounds are highly potent and efficacious, with N-[1-(4-chlorophenyl)-3-(dimethylamino)-propyl]-4-phenylbenzamide oxalate (5d) being the most potent. The pure enantiomers of 5d were obtained from the corresponding diastereomeric amides. It was shown by a combination of X-ray crystallography and chemical correlation that the activity resides in the S-enantiomer of 5d (pEC(50) 7.49).

Alanine substitution and deletion analogues of Manduca sexta allatostatin: structure-activity relationship on the spontaneous contractions of the foregut of larval Lacanobia oleracea

Manduca sexta allatostatin (Manse-AS) is a 15-residue non-amidated peptide with a blocked N-terminus and a disulphide bridge between the cysteine residues at positions 7 and 14. Analogues of Manse-AS were used to examine the structural requirements of Manse-AS for inhibitory activity on spontaneous foregut contractions of larval tomato moth (Lacanobia oleracea). Breaking the disulphide bond between C(7) and C(14) by reduction reduced the potency of the peptide, suggesting that the conformation of Manse-AS is important for its biological activity. When either of the cysteine residues were replaced with alanine the Manse-AS analogue had no measurable bioactivity. Alanine substitution at Q(6) was as potent as Manse-AS, all other alanine substitution analogues (R(5), Y(8), F(9), N(10), P(11), I(12) and S(13)), were myoinhibitory but less potent than native Manse-AS to varying degrees. Analogues with alanine substitution at amino acids with aromatic side chains (Y(8) and F(9)) were the least active. Amino-terminal deletion analogues Manse-AS(6-15) and Manse-AS(7-15) were inactive whereas Manse-AS(5-15) was fully active but not as potent as Manse-AS. The results show that amino acid residues both inside and outside the disulphide ring are important for biological activity.

Arrestin-Independent Internalization and Recycling of the Urotensin Receptor Contribute to Long-Lasting Urotensin II–Mediated Vasoconstriction

Urotensin II (UII), which acts on the G protein-coupled urotensin (UT) receptor, elicits long-lasting vasoconstriction. The role of UT receptor internalization and intracellular trafficking in vasoconstriction has yet not been analyzed. Therefore, UII-mediated contractile responses of aortic ring preparations in wire myography and rat UT (rUT) receptor internalization and intracellular trafficking in binding and imaging analyses were compared. UII elicited a concentration-dependent vasoconstriction of rat aorta (-log EC50, mol/L:9.0+/-0.1). A second application of UII after 30 minutes elicited a reduced contraction (36+/-4% of the initial response), but when applied after 60 minutes elicited a full contraction. In internalization experiments with radioactive labeled VII ((125)I-UII), approximately 70% of rUT receptors expressed on the cell surface of human embryonic kidney 293 cells were sequestered within 30 minutes (half life [t(h)]: 5.6+/-0.2 minutes), but recycled quantitatively within 60 minutes (t(h) 31.9+/-2.6 minutes). UII-bound rUT receptors were sorted to early and recycling endosomes, as evidenced by colocalization of rUT receptors with the early endosomal antigen and the transferrin receptor. Real-time imaging with a newly developed fluorescent UII (Cy3-UII) revealed that rUT receptors recruited arrestin3 green fluorescent protein to the plasma membrane. Arrestin3 was not required for the endocytosis of the rUT receptor, however, as internalization of Cy3-UII was not altered in mouse embryonic fibroblasts lacking endogenous arrestin2/arrestin3 expression. The data demonstrate that the rUT receptor internalizes arrestin independently and recycles quantitatively. The continuous externalization of rUT receptors provides the basis for repetitive and lasting UII-mediated vasoconstriction.