Comparative evaluation of urinary PCA3 and TMPRSS2: ERG scores and serum PHI in predicting prostate cancer aggressiveness.

It has been suggested that urinary PCA3 and TMPRSS2:ERG fusion tests and serum PHI correlate to cancer aggressiveness-related pathological criteria at prostatectomy. To evaluate and compare their ability in predicting prostate cancer aggressiveness, PHI and urinary PCA3 and TMPRSS2:ERG (T2) scores were assessed in 154 patients who underwent radical prostatectomy for biopsy-proven prostate cancer. Univariate and multivariate analyses using logistic regression and decision curve analyses were performed. All three markers were predictors of a tumor volume≥0.5 mL. Only PHI predicted Gleason score≥7. T2 score and PHI were both independent predictors of extracapsular extension(≥pT3), while multifocality was only predicted by PCA3 score. Moreover, when compared to a base model (age, digital rectal examination, serum PSA, and Gleason sum at biopsy), the addition of both PCA3 score and PHI to the base model induced a significant increase (+12%) when predicting tumor volume>0.5 mL. PHI and urinary PCA3 and T2 scores can be considered as complementary predictors of cancer aggressiveness at prostatectomy.

Peptide histidine-methionine immunoreactivity in plasma and tissue from patients with vasoactive intestinal peptide-secreting tumors and watery diarrhea syndrome.

The presence of peptide histidine-methionine (PHM)-like peptides has been determined in plasma and tumor specimens from patients with vasoactive intestinal peptide (VIP)-secreting tumors and the watery diarrhea syndrome. All patients had strikingly elevated plasma concentrations of PHM immunoreactivity (median, 1800; range, 500-6800 pmol/liter; n = 12), which were higher than those of VIP (median, 235; range, 50-580 pmol/liter). In patients with other endocrine and nonendocrine pancreatic tumors, plasma PHM concentrations were not significantly different from normal (median, 20; range, 5-60 pmol/liter; n = 28). Plasma samples from patients with diarrhea due to other illnesses also had PHM concentrations that were not significantly different from normal (median, 40; range, 10-80 pmol/liter; n = 23). The gel chromatographic profiles of plasma and tumor extracts from patients with VIP-secreting tumors revealed the presence of at least two molecular forms that reacted with an antiserum directed to the N-terminus of PHM (SY1). The later peak (Kav, 0.50-0.53) corresponded in position to synthetic PHM and also reacted with the PHM-specific antiserum (SY2). The earlier peak (Kav, 0.30-0.37), not reactive with antiserum SY2, corresponded to a large molecular form of PHM-like immunoreactivity previously identified as the predominant form in normal human stomach and plasma, though not in the rest of the intestinal tract. The neuroendocrine nature of the tumors was confirmed by the demonstration of immunostaining with a battery of antisera to neuroendocrine markers. Immunocytochemistry revealed the presence of both VIP and PHM in tumor cells. The presence of high circulating concentrations of PHM-like immunoreactivity in patients with VIP-secreting tumors, as measured with a PHM N-terminus-directed antiserum, SY1, suggests that use of this type of antiserum may provide valuable information in the diagnosis of such tumors. The contribution of the PHM-like peptides to the features of this syndrome is not known.

Co-release of PHI and VIP in dog stomach by peripheral and central vagal stimulation.

1. The purpose of this investigation was to examine the outputs of peptide histidine isoleucine (PHI) and vasoactive intestinal peptide (VIP) from the gastric corpus in response to stimulation of the peripheral (PVS) and central (CVS) ends of the vagus nerve and to compare the effects of PHI on gastric motility and blood flow with those of VIP in atropine-treated dogs. 2. PVS and CVS caused parallel increases in gastric venous plasma concentrations of VIP and PHI. The molar ratios of the peptides (VIP/PHI) appearing in the gastric venous plasma were about 1.5 for PVS at 10 Hz, 0.65 for PVS at 40 Hz and about 0.7 for CVS at 10 Hz. 3. The molar ratio of peptide concentration extracted from the gastric corpus was about 1.5 in the muscle layer and 2.7 in the mucosal layer. 4. Intra-arterially-injected PHI was about 5 fold and 50 fold less effective in producing gastric relaxation and vasodilatation, respectively, than VIP. 5. These results indicate that PHI is co-released with VIP by peripheral vagal stimulation and by initiation of the vago-vagal reflex, and that PHI seems to have an important role in the regulation of gastric motility but not gastric blood flow in the dog.

Potential incretins.

A greater plasma concentration of insulin after isoglycemic enteral than after parenteral administration of glucose is called the incretin effect. The primary mediator of this effect, gastric inhibitory polypeptide, may not account for the complete manifestation of this phenomenon. We evaluated other gastroenteric polypeptides with respect to a differential response to oral ingestion of glucose and intravenous administration of glucose at rates that achieved arterial plasma glucose concentrations matched to those from orally administered glucose. Gastrin, peptide histidine methionine, peptide YY, and neurotensin showed increases in plasma concentrations in response to oral ingestion of glucose but not to intravenous administration of glucose. Vasoactive intestinal polypeptide showed no increased concentration in response to either oral or intravenous administration of glucose. The differential responses to orally and intravenously administered glucose noted in the former gastroenteric polypeptides qualifies them as potential mediators of the incretin effect.

Cosecretion of peptide histidine methionine (PHM) and vasoactive intestinal peptide (VIP) in patients with VIP-producing tumors.

Regional specific antibodies and chromatography were used to analyze the concentration and molecular forms of vasoactive intestinal peptide (VIP) and peptide histidine methionine (PHM) in plasma from 39 patients with VIP-producing tumors. Plasma VIP concentrations ranged from 29 to 2550 pmol/l and the corresponding PHM immunoreactive values measured with C-terminally directed antibody were 42 to 2100 pmol/l which correlated closely with the VIP concentrations. N-terminal PHM concentrations were significantly higher than the C-terminal values ranging from 92 to 5850 pmol/l and correlated poorly with the corresponding VIP concentrations. Infusion experiments with PHM disclosed that the higher levels of N-terminal immunoreactivity could not be explained by slower metabolic clearance or by degradation to smaller N-terminal immunoreactive forms. N-terminally directed PHM antibody revealed, in addition to intact PHM, a larger immunoreactive form in patient plasma which constituted the major proportion of the total immunoreactivity. In conclusion, VIP and PHM are cosecreted from VIPomas and measurement of PHM, especially N-terminal immunoreactivity, may be useful in this condition.

Peptide histidine methionine and vasoactive intestinal peptide levels in human cerebrospinal fluid: age-related changes and absence of a correlation with serum prolactin.

Serum levels of prolactin (PRL), peptide histidine methionine (PHM) and vasoactive intestinal peptide (VIP) were measured in 97 subjects and cerebrospinal fluid (CSF) levels of PHM and VIP were measured in 50 subjects by specific radioimmunoassays to investigate correlations between them. The chromatographic studies revealed that PHM and C-terminal extended form of PHM, peptide histidine valine occurred in human serum and CSF. Significant age-related increases of CSF PHM (P < 0.02) were observed in both males and females, whereas an age-related decrease of serum PRL level was found in females (P < 0.01). In contrast, neither serum VIP, serum PHM nor CSF VIP changed significantly with age. There was a significant positive correlation (P < 0.002) between VIP and PHM in serum, but not in CSF. The close relation between VIP and PHM in serum meets one's expectation because of their derivation from a common precursor. In CSF, these two peptides did not change in parallel with each other. These results may reflect the alteration in metabolism of PHM in CSF. Finally, there was no correlation between serum PRL concentrations and either serum or CSF levels of the peptides, suggesting that neither VIP nor PHM levels in CSF as well as in serum can influence the basal PRL secretion in subjects without endocrine disorders.

Vagal-induced tachycardia: release of vasoactive intestinal peptide and peptide HI.

The relationship between vagal-induced tachycardia (VT) and release of vasoactive intestinal peptide (VIP) and peptide HI (PHI) into cardiac lymph and coronary sinus blood was studied in 23 alpha-chloralose-anesthetized open-chest dogs that were autonomically decentralized and pretreated with atropine and propranolol. After simultaneous right and left cervical vagal stimulation at 5 V, 20 Hz for 3 min mean +/- SE, increase in heart rate was 38 +/- 6 beats/min, and increase in lymph VIP output from control was 0.308 +/- 0.093 pg/min (P = 0.004). The decrease in VIP arterial minus coronary sinus concentration was not significant. The increase in heart rate did not significantly correlate with increase in lymph VIP output (R2 = 0.141) or decrease in VIP arterial minus coronary sinus concentration (R2 = 0.059). The increases in heart rate and lymph VIP output were blocked by hexamethonium. Increase in lymph PHI output from control during VT (5 dogs) was 0.797 +/- 0.658 pg/min. Arterial-coronary sinus PHI concentration difference did not change in these dogs. These data indicate that VT is associated but not significantly correlated with VIP and PHI release into cardiac lymph. Cholinoceptive nicotinic receptors may mediate VIP release and VT in anesthetized dogs.

Dipeptidyl-peptidase IV hydrolyses gastric inhibitory polypeptide, glucagon-like peptide-1(7-36)amide, peptide histidine methionine and is responsible for their degradation in human serum.

Peptides of the glucagon/vasoactive-intestinal-peptide (VIP) peptide family share a considerable sequence similarity at their N-terminus. They either start with Tyr-Ala, His-Ala or His-Ser which might be in part potential targets for dipeptidyl-peptidase IV, a highly specialized aminopeptidase removing dipeptides only from peptides with N-terminal penultimate proline or alanine. Growth-hormone-releasing factor (1-29)amide and gastric inhibitory peptide/glucose-dependent insulinotropic peptide (GIP) with terminal Tyr-Ala as well as glucagon-like peptide-1(7-36)amide/insulinotropin [GLP-1(7-36)amide] and peptide histidine methionine (PHM) with terminal His-Ala were hydrolysed to their des-Xaa-Ala derivatives by dipeptidyl-peptidase IV purified from human placenta. VIP with terminal His-Ser was not significantly degraded by the peptidase. The kinetics of the hydrolysis of GIP, GLP-1(7-36)amide and PHM were analyzed in detail. For these peptides Km values of 4-34 microM and Vmax values of 0.6-3.8 mumol.min-1.mg protein-1 were determined for the purified peptidase which should allow their enzymic degradation also at physiological, nanomolar concentrations. When human serum was incubated with GIP or GLP-1(7-36)amide the same fragments as with the purified dipeptidyl-peptidase IV, namely the des-Xaa-Ala peptides and Tyr-Ala in the case of GIP or His-Ala in the case of GLP-1(7-36)amide, were identified as the main degradation products of these peptide hormones. Incorporation of inhibitors specific for dipeptidyl-peptidase IV, 1 mM Lys-pyrrolidide or 0.1 mM diprotin A (Ile-Pro-Ile), completely abolished the production of these fragments by serum. It is concluded that dipeptidyl-peptidase IV initiates the metabolism of GIP and GLP-1(7-36)amide in human serum. Since an intact N-terminus is obligate for the biological activity of the members of the glucagon/VIP peptide family [e. g. GIP(3-42) is known to be inactive to release insulin in the presence of glucose as does intact GIP], dipeptidyl-peptidase-IV action inactivates these peptide hormones. The relevance of this finding for their inactivation and their determination by immunoassays is discussed.

Corelease of PHI and VIP by vagal stimulation in the dog.

Electrical vagal stimulation increased immunoreactive peptide histidine isoleucine (IR-PHI) and vasoactive intestinal polypeptide (IR-VIP) levels in the portal plasma in anesthetized dogs, depending on the stimulation frequency. Atropine failed to suppress the vagal release of IR-PHI and IR-VIP, whereas hexamethonium abolished the increase of both peptide immunoreactivities. Gel filtration profiles of IR-PHI and IR-VIP in the portal plasma obtained during vagal stimulation revealed major peaks of IR-PHI and IR-VIP eluting in the same positions as synthetic PHI-27 and VIP-28, respectively. These data demonstrate that PHI and VIP are coreleased by vagal stimulation via a nicotinic ganglionic mechanism. An additional peak of larger molecular weight IR-PHI was observed in gel filtration of the portal plasma obtained under higher frequency vagal stimulation, when measured by the N-terminal-specific PHI antiserum. The presence of this larger form of IR-PHI together with a PHI-27-like component was also demonstrated in tissue extracts of the entire length of the gastrointestine, particularly in higher concentration in the stomach. The structure and the physiological significance of this larger form of IR-PHI remains to be elucidated.

Effects of acute and long-term atropine treatment on levels, release and response to VIP and PHI in the submandibular gland of cat and rat.

We have studied the effects of acute and long-term treatment of cats and rats with atropine on the levels, release and effects of two peptides, vasoactive intestinal polypeptide (VIP) and peptide histidine isoleucine (PHI), that probably co-exist with acetylcholine in the parasympathetic nerves supplying the submandibular gland. Atropine treatment (progressively increasing doses from 2 to 15 mg kg-1 injected s.c.) for 14 days did not alter the contents of VIP- or PHI-like immunoreactivity (-IR) in the cat submandibular gland or in three other tissues (nasal mucosa, trachea and tongue). Acute as well as long-term atropine treatment decreased the vasodilation following low-, but not high-, frequency parasympathetic nerve stimulation. During prolonged stimulation (60 min) there was a decreased vasodilatation response following both acute and long-term atropine treatment. The overflow of VIP-IR and PHI-IR following parasympathetic nerve stimulation was markedly increased by acute, but not by long-term atropine treatment. The VIP- or PHI-induced stimulation of cyclic AMP (cAMP) accumulation in the cat submandibular gland was not altered after long-term atropine treatment. Similarly, treatment of male Sprague-Dawley rats with atropine (20 mg kg-1) or imipramine (20 mg kg-1) for 14 days did not alter the sensitivity to VIP or to PHI of cAMP accumulation in the submandibular gland, nor was there any change in VIP-IR or PHI-IR content. In conclusion, although atropine treatment causes an acute increase in the overflow of VIP and PHI evoked by parasympathetic nerve stimulation, there is no depletion of peptide stores upon long-term treatment, nor is there any change in the effect of exogenous VIP and PHI on cAMP-accumulation.