The effect of urocortin 1 on motility in isolated, vascularly perfused rat colon

Urocortin-1 promotes colorectal cancer cell migration and proliferation and inhibits apoptosis via inhibition of the p53 signaling pathway

PURPOSE

To investigate the effect of urocortin-1 (UCN-1) on growth, migration, and apoptosis in colorectal cancer (CRC) in vivo and vitro and the mechanism by which UCN-1 modulates CRC cells in vitro.

METHODS

The correlation between UCN-1 and CRC was evaluated using The Cancer Genome Atlas (TCGA) database and a tissue microarray. The expression of UCN-1 in CRC cells was assessed using quantitative real-time polymerase chain reaction (RT-qPCR) and western blotting. In vitro, the influence of UCN-1 on the proliferation, apoptosis, and migration of HT-29, HCT-116, and RKO cells was explored using the celigo cell counting assay or cell counting kit-8 (CCK8), flow cytometry, and wound healing or Transwell assays, respectively. In vivo, the effect of UCN-1 on CRC growth and progression was evaluated in nude mice. The downstream pathway underlying UCN-1-mediated regulation of CRC was determined using the phospho-kinase profiler array in RKO cells. Lentiviruses were used to knockdown or upregulate UCN-1 expression in cells.

RESULTS

Both the TCGA and tissue microarray results showed that UCN-1 was strongly expressed in the tissues of patients with CRC. Furthermore, the tissue microarray results showed that the expression of UCN-1 was higher in male than in female patients, and high expression of UCN-1 was associated with higher risk of lymphatic metastasis and later pathological stage. UCN-1 knockdown caused a reduction in CRC cell proliferation, migration, and colony formation, as well as an increase in apoptosis. In xenograft experiments, tumors generated from RKO cells with UCN-1 knockdown exhibited reduced volumes and weights. A reduction in the expression of Ki-67 in xenograft tumors indicated that UCN-1 knockdown curbed tumor growth. The human phospho-kinase array showed that the p53 signaling pathway participated in UCN-1-mediated CRC development. The suppression in migration and proliferation caused by UCN-1 knockdown was reversed by inhibitors of p53 signal pathway, while the increase in cell apoptosis was suppressed. On the other hand, overexpression of UCN-1 promoted proliferation and migration and inhibited apoptosis in CRC cells. Overexpression of p53 reversed the effect of UCN-1 overexpression on CRC development.

CONCLUSION

UCN-1 promotes migration and proliferation and inhibits apoptosis via inhibition of the p53 signaling pathway.

Urocortin-positive nerve fibres and cells are present in the human choroid

BACKGROUND

Choroidal vascular regulation is mediated by the autonomic nervous system in order to gain proper blood flow control. While the mechanisms behind this control are unknown, neuroregulatory peptides are involved in this process. To better understand choroidal function, we investigate the presence of urocortin-1 (UCN), a neuroregulatory peptide with vascular effects, in the human choroid and its possible intrinsic and extrinsic origin.

METHODS

Human choroid and eye-related cranial ganglia (superior cervical ganglion- SCG, ciliary ganglion-CIL, pterygopalatine ganglion-PPG, trigeminal ganglion-TRI) were prepared for immunohistochemistry against UCN, protein-gene product 9.5 (PGP9.5), substance P (SP), tyrosine hydroxylase (TH) and vesicular acetylcholine transporter (VAChT). For documentation, confocal laser scanning microscopy was used.

RESULTS

In choroidal stroma, UCN-immunoreactivity was present in nerve fibres, small cells and intrinsic choroidal neurons (ICN). Some UCN+ nerve fibres colocalised for VAChT, while others were VAChT. A similar situation was found with SP: some UCN+ nerve fibres showed colocalisation for SP, while others lacked SP. Colocalisation for UCN and TH was not observed. In eye-related cranial ganglia, only few cells in the SCG, PPG and TRI were UCN+, while many cells of the CIL displayed weak UCN immunoreactivity.

CONCLUSION

UCN is part of the choroidal innervation. UCN+/VAChT+ fibres could derive from the few cells of the PPG or cells of the CIL, if these indeed supply the choroid. UCN+/SP+ fibres might originate from ICN, or the few UCN+ cells detected in the TRI. Further studies are necessary to establish UCN function in the choroid and its implication for choroidal autonomic control.