Elsevier

Surgery

Volume 142, Issue 6, December 2007, Pages 959-964
Surgery

American Association of Endocrine Surgeons
Neuroendocrine tumor cell growth inhibition by ZM336372 through alterations in multiple signaling pathways

Presented at the Annual meeting of the American Association of Endocrine Surgeons, Tucson, AZ, April 29-May 1, 2007.
https://doi.org/10.1016/j.surg.2007.09.020Get rights and content

Background

We have shown previously that activation of the Raf-1/mitogen-activated protein kinase (MEK)/extracellular signal-regulated kinase (ERK)1/2 signaling pathway by ZM336372 inhibits carcinoid cells growth. In the present study, we further characterize the molecular details of the growth inhibition by the signaling-based compound ZM336372 in neuroendocrine neoplasms (NENs).

Methods

NEN cells were treated with ZM336372 (20 to 100 μmol/L) or carrier (DMSO). Western Blot was used to determine the activation of the Raf-1/MEK/ERK, other pathways activation, and cellular bioactive hormone production.

Results

ZM336372 in NEN cells resulted in increasing raf-1 activation and inactivation of glycogen synthase kinase-3 beta (GSK-3β) as measured by phosphorylation of ERK1/2 and GSK-3β, respectively. There was no alteration in the levels of phosphorylated Akt, an important mediator of the phosphatidyl inositol 3 kinase pathway. Importantly, blocking of raf-1 pathway by U0126, a potent inhibitor, in the presence of ZM336372 did not reduce the levels of p-GSK-3β, indicating that GSK-3β inactivation is independent of raf-1 pathway activation. Moreover, the levels of chromogranin A and achaete–scute complex like-1 reductions were persistent even after blocking the raf-1 pathway. Treatment with ZM336372 in the presence of small interfering RNA against raf-1 resulted in an increase in Raf-1 production, suggesting that ZM336372 upregulates raf-1 at the transcriptional level.

Conclusion

This is the first description of a novel compound ZM336372 that regulates multiple pathways in NEN cells.

Section snippets

Cell culture

TT and human bronchopulmonary carcinoid (H727) cells were obtained from ATCC and maintained in RPMI 1640 (Invitrogen, Carlsbad, CA) supplemented with fetal bovine serum (Sigma, St. Louis, MO), 100 IU/mL penicillin, and 100 μg/mL streptomycin (Invitrogen) in a humidified atmosphere of 5% CO2 in air at 37°C as described.4, 11, 14

ZM336372 treatment

TT or H727 cells were plated onto 100-mm dishes. The following day, media was changed to fresh media containing varying concentrations of ZM336372 (0 to 200 μmol/L) and

ZM336372 inhibits cellular growth in TT cells

We have reported that treatment of carcinoid cells (BON and H727) with ZM336372 resulted in activation of raf-1 pathway that was associated with growth inhibition.13 Furthermore, we reported recently that inhibition of pheochromocytoma (PC12) cell growth in vitro by ZM336372 was shown to be associated with raf-1 pathway activation15; however, the effect of ZM336372 on the growth of TT cells is not known. We have done cytotoxic experiment with different cell lines including TT and observed that,

Discussion

NENs such as MTC and carcinoid neoplasms represent a diverse group of neoplasms with unique clinical presentations. NENs metastasize frequently to distant organs. Endocrinopathies related to the production of various amines and peptides from these neoplasms can result in debilitating symptoms. Operative resection is the only curative therapy for patients with NENs, but complete resection is often not possible owing to the metastatic nature of the disease. Therefore, there is a great need for

References (15)

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Supported in part by a Research Scholars Grant from the American Cancer Society, National Institutes of Health grants DK064735, DK066169 and CA109053; the George H.A. Clowes, Jr., Memorial Research Career Development Award of the American College of Surgeons, the Carcinoid Cancer Foundation Award (HC) the University of Wisconsin Medical School Grant (MK); and the Robert Draper Technology Innovation award (MK).

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