In vitro activity: PACAP 1-38 is a pleiotropic neuropeptide, exhibiting a variety of biologic actions, including activities as a neurotransmitter, neuromodulator, neurotrophic factor, as well as an immunomodulator, in immune cells through its effect on MAPK signaling and modulation of activation of NFκB. PACAP 1-38 dramatically prevents injury of cultured renal proximal tubule cells caused by myeloma light chains through suppression of proinflammatory cytokines production, by inhibiting p38 MAPK and translocation of NFκB via both PAC1 and VPAC1 receptors. PACAP38 inhibits myeloma cell growth directly and may also indirectly by suppressing production of the growth factor, IL-6, from bone marrow stromal cells, that is stimulated by adhesion of myeloma cells. PACAP38 suppressed release of both IL-6 and TNFα dose dependently.

Kinase Assay: PACAP (1-38), human, ovine, rat is a neuropeptide with 38 amino acid residues. PACAP (1-38) binds to PACAP type I receptor, PACAP type II receptor VIP1, and PACAP type II receptor VIP2 with IC50s of 4 nM, 2 nM, and 1 nM, respectively.

Cell Assay: Human renal proximal tubule cells plated onto 6-well tissue culture plates are grown at 37°C in DRM-23E medium supplemented with 0.5% (vol/vol) FBS in an incubator for 24 hours. After prewashing with serum-free medium, the cells are incubated with κ-LC (1.5 mg/ml, ~ 50 μM) for 3 days in the presence and absence of various concentrations of PACAP38 or dexamethasone as well as kinase and transcription factor inhibitors. Cell viability is determined by trypan blue exclusion assays; in all experiments, at least 85% of cells remain viable. After exposure to test substances, culture supernatants are harvested and stored at –70°C for cytokine assays. After the medium is removed, the cells are washed with ice-cold PBS, and proteins are extracted by lysing cells with Sigma Mammalian Cell Lysis Reagents. Lysates are scraped and passed through a 21-gauge needle to shear DNA, and centrifuged at 12 000g for 10 minutes at 4°C. Finally, supernatants are harvested and used for kinase studies.