Vasoactive intestinal peptide and forskolin regulate proliferation of the HT29 human colon adenocarcinoma cell line

Abstract

Although several lines of evidence implicate cAMP in the regulation of intestinal cell proliferation, the precise role of this second messenger in the control of the human colon cancer cell cycle is still unclear. In order to investigate the role of cAMP in HT29 cell proliferation, we have tested the effect of vasoactive intestinal peptide (VIP) and forskolin on DNA synthesis and cell number, focusing on the time-dependent efficacy of the treatment. The cells were arrested in G0/G1 phase by incubation for 24 h in serum-free medium and proliferation was re-initiated by addition of either 85 nM insulin or 0.5% fetal calf serum. In the presence of fetal calf serum, G1/S transition was found to occur earlier than with insulin. Exposure of the HT29 cells to 10(-5) M forskolin in the early stages of growth induction (within 12 h from FCS addition or within 14 h from insulin treatment) resulted in a significant inhibition of DNA synthesis and a delayed entry in the S phase. By contrast, VIP (10(-7) M) was inhibitory only when added within a narrow window (10 to 12 h or 12 to 14 h following FCS or insulin addition, respectively). The difference in efficiency of forskolin and VIP to inhibit cell proliferation may be correlated with their own potency to promote long-lasting cAMP accumulation. The combination of VIP plus forskolin had synergistic effects on both cAMP accumulation and cell-growth inhibition. Taken together, our data indicate that cAMP may act at a step in the late G1 or G1/S transition.

VIPoma with expression of both VIP and VPAC1 receptors in a patient with WDHA syndrome

“…Indeed, the VPAC1 receptor coupling to both adenylyl cyclase and phospholipase C has been demonstrated in certain cell types [18], and cAMP analogs, such as 8-Cl-or N 6 -benzyl-cAMP, were found to inhibit the growth of several human colon cancer cell lines, including HT29 [19]. This inhibition was due to delayed G1/S transition and a reduced rate of DNA synthesis rather than a cytotoxic effect [17]. Dose-related inhibition of cell proliferation by VIP and concentration-dependent increases in cAMP induced by VIP were reported [13,15].…”

“…Although little is known about the role of VIP as a mediator of normal and neoplastic pancreatic duct cell growth, VIP clearly regulates the growth of other normal and neoplastic cells. VIP inhibits the growth of small cell lung cancer [15], neuroblastoma cells [16], gastric carcinoma cells [12], and colonic adenocarcinoma cells in vitro [17]. The ability of VIP to inhibit cell growth appears to be linked to adenylyl cyclase activation.…”

Proliferation of hepatic stellate cells is inhibited by phosphorylation of CREB on serine 133.

“…However, little is known about the signal transduction pathways and the nuclear factors involved in either the normal, quiescent or the activated, proliferating phenotype of hepatic stellate cells. Because stimulation of the cyclic adenosine 3 Ј ,5 Ј monophosphate (cAMP)-dependent protein kinase (PKA) 1 inhibits proliferation of some tumoral cell lines (13)(14)(15), we analyzed the potential role of this signal transduction pathway on stellate cell proliferation.…”

Intestinal Immunomodulation. Role of Regulative Peptides and Promising Pharmacological Activities

“…In vitro studies have demonstrated that several intestinal regulative peptides have a significant role in regulating the proliferation and growth of epithelial intestinal cells; these molecules are also involved in regulating immunological responses; both proliferation and immune defense are important in the development and growth of CRC [319,320,321,322,323,324].…”