Effector mechanisms of peptides of the VIP family

Growth hormone-releasing hormone antagonist MZ-5-156 inhibits growth of DU-145 human androgen-independent prostate carcinoma in nude mice and suppresses the levels and mRNA expression of insulin-like growth factor II in tumors

“…In addition, a significant reduction in concentration of IGF-I was produced in osteosarcomas (23), renal cancers, and PC-3 prostate tumors as well as in non-SCLCs (21,22,24) peptide, and pituitary adenylate cyclase-activating peptide (PACAP) (40,41). These peptides demonstrate considerable amino acid sequence homology (40,41). The human and rat GH-RH receptors are homologous to secretin and VIP receptor proteins (42).…”

“…However, the results of this investigation and previous studies (18,21,22,24) demonstrate that a major decrease in tumor IGF-II levels also is found in Caki-I renal carcinomas, PC-3, and DU-145 prostate cancers, and H-157 non-SCLC xenografted into nude mice after therapy with GH-RH antagonists. In addition, a significant reduction in concentration of IGF-I was produced in osteosarcomas (23), renal cancers, and PC-3 prostate tumors as well as in non-SCLCs (21,22,24) peptide, and pituitary adenylate cyclase-activating peptide (PACAP) (40,41). These peptides demonstrate considerable amino acid sequence homology (40,41).…”

“…VIP 1 and PACAP receptors have been identified in certain tumors (43). GH-RH can compete for binding to common receptor proteins, such as the VIP receptor, and produce similar biologic responses in many target organs (40,41,44,45). GH-RH antagonists might also bind with reduced affinity to some of these receptors in tumors.…”

Structural requirements for the occupancy of pituitary adenylate‐cyclase‐activating‐peptide (PACAP) receptors and adenylate cyclase activation in human neuroblastoma NB‐OK‐1 cell membranes

“…PACAP(2-27) was already 50-fold less potent than PACAP(1-27) for binding but retained 90% of its intrinsic effect on adenylate cyclase. In line with other members of this family of peptides (including VIP, secretin and glucagon) [17,18,[23][24][25][26][27][28][29][30][31][32][33], it appears that, upon receptor recognition, the first two residues of PACAP(1-27) played an important role in adenylate cyclase activation, but the N-terminal His1 was not absolutely required. After further deletion, the of PACAP(3 -27), PACAP(5 -27), PACAP(6 -27), PACAP(7 -27) and PACAP(9 -27) were, respectively, 1 500-, 500-, 200-, 1500-and 3800-fold higher than that of PACAP(1-27), and these five PACAP fragments, having lost the ability to stimulate adenylate cyclase, behaved as antagonists (Table 2), i.e.…”

Growth hormone-releasing hormone: An autocrine growth factor for small cell lung carcinoma

“…GHRH is a member of the family of peptides that includes glucagon, secretin, vasoactive intestinal peptide (VIP), gastric inhibitory peptide, and pituitary adenylate cyclase-activating peptide (PACAP). A considerable structural homology exists between these peptides as well as among the corresponding receptors (26). Thus, GHRH appears to compete for binding to an unknown member of this family of receptors expressed in tumors and one that is likely related to VIP͞GHRH receptor proteins.…”