Expression analysis of secreted and cell surface genes of five transformed human cell lines and derivative xenograft tumors

BACKGROUND: Since the early stages of tumorigenesis involve adhesion, escape from immune surveillance, vascularization and angiogenesis, we devised a strategy to study the expression profiles of all publicly known and putative secreted and cell surface genes. We designed a custom oligonucleotide microarray containing probes for 3531 secreted and cell surface genes to study 5 diverse human transformed cell lines and their derivative xenograft tumors. The origins of these human cell lines were lung (A549), breast (MDA MB-231), colon (HCT-116), ovarian (SK-OV-3) and prostate (PC3) carcinomas. RESULTS: Three different analyses were performed: (1) A PCA-based linear discriminant analysis identified a 54 gene profile characteristic of all tumors, (2) Application of MANOVA (Pcorr < .05) to tumor data revealed a larger set of 149 differentially expressed genes. (3) After MANOVA was performed on data from individual tumors, a comparison of differential genes amongst all tumor types revealed 12 common differential genes. Seven of the 12 genes were identified by all three analytical methods. These included late angiogenic, morphogenic and extracellular matrix genes such as ANGPTL4, COL1A1, GP2, GPR57, LAMB3, PCDHB9 and PTGER3. The differential expression of ANGPTL4 and COL1A1 and other genes was confirmed by quantitative PCR. CONCLUSION: Overall, a comparison of the three analyses revealed an expression pattern indicative of late angiogenic processes. These results show that a xenograft model using multiple cell lines of diverse tissue origin can identify common tumorigenic cell surface or secreted molecules that may be important biomarker and therapeutic discoveries

Norepinephrine and neuropeptide Y: vasoconstrictor cooperation in vivo and in vitro

Norepinephrine (NE)-evoked vasoconstrictor and pressor responses are reduced after prolonged exposure; such desensitization is observed both clinically and experimentally. The vasoconstrictor neuropeptide Y (NPY) coexists with NE in perivascular sympathetic nerves, and the results of both in vivo and in vitro studies have indicated functional cooperation between NE and NPY. We propose that NPY becomes increasingly important in situations of high sympathetic activity associated with blunted NE responses. Prolonged NE infusion in conscious rats resulted in adrenergic desensitization; however, NPY administration restored the responsiveness to NE. In naive rats, NE greatly enhanced the pressor action of NPY. An analogous phenomenon was observed in the rabbit isolated pulmonary artery, which failed to respond to NPY unless preexposed to NE; this action of NE was only partly inhibited by conventional adrenoceptor and Ca2+ influx blockade. Conversely, NPY enhanced NE-evoked constriction, in particular when the alpha-adrenoceptor reserve was eliminated. It is proposed that threshold synergism, in part caused by converging stimulation of phospholipase C, accounts for much of the NPY/NE cooperativity. We conclude that 1) NPY and NE cooperate to produce vasoconstriction, both in vivo and in vitro; 2) NPY has the capacity to reverse adrenergic desensitization but not vice versa; 3) NE enhances NPY-evoked vasoconstriction, in part independently of conventional adrenoceptor blockade; 4) threshold synergism phenomena, but not "receptor-receptor interactions," account for (most of) the observed NPY/NE cooperation; and 5) when present, alpha-adrenoceptor reserve prevents the lowering of the NE threshold by NPY

Biphasic blood pressure response to neuropeptide Y in anesthetized rats

The effects of neuropeptide Y (NPY) on systemic arterial blood pressure and heart rate were studied in anesthetized intact and pithed rats. I.v. doses of NPY (0.3-30 nmol/kg) raised the mean arterial blood pressure dose dependently. At doses of greater than or equal to 3.0 nmol/kg, the initial pressor response was followed by a dose-dependent fall in blood pressure in intact and pithed rats. The depressor response was accompanied 1-2 min after the NPY injection by a slight increase in heart rate in pithed rats but not in intact rats, and 10 min after the injection by a decrease in heart rate in intact rats. After repeated injections of NPY, the depressor effect vanished, whereas the integrated pressor response over time was markedly enhanced. After pretreatment with the histamine H1-receptor antagonist, mepyramine, or with the histamine liberator, compound 48/80, the pressor response to NPY remained but the depressor response disappeared. We suggest that the marked fall in blood pressure can be attributed to NPY-evoked histamine release from mast cells

C-terminal neuropeptide Y fragments are mast cell-dependent vasodepressor agents

Neuropeptide Y (NPY) is a well-established vasopressor agent present in sympathetic perivascular nerves. Recently, it was found that high doses of the peptide cause a biphasic pressor-depressor response upon intravenous administration. We now report that C-terminal NPY fragments (NPY-(18-36) and NPY-(22-36] given intravenously to conscious or pithed (areflexive) male Sprague-Dawley rats mimic the depressor component of the NPY-(1-36) response while displaying very low pressor activity. Additionally, we have found that the depressor component is blocked by the histamine H1-antagonist, mepyramine. Since the fragment, NPY-(22-36), was equipotent with NPY in inducing histamine release from isolated peritoneal mast cells, we conclude that short C-terminal NPY fragments, like NPY itself, act on mast cells to initiate histamine-mediated cardiovascular actions. Such actions may conceivably be accounted for by the abundance of positively charged amino acid residues in the C-terminus. Moreover, these fragments have little affinity for vascular NPY receptors, as indicated by their poor ability to displace iodinated NPY or peptide YY (PYY) from specific binding sites on vascular smooth muscle cells derived from rat aorta. In conclusion, we propose that short C-terminal NPY fragments, which contain several positively charged amino acid residues, retain the ability of NPY to release histamine from rat mast cells while being essentially devoid of direct vascular motor activity