Synthetic Makaluvamine Analogs Decrease c-Kit Expression and Are Cytotoxic to Neuroendocrine Tumor Cells.

Sadanandan E Velu,Renata Jaskula-Sztul,Zviadi Aburjania,Dwayaja H Nadkarni,Samuel Jang,Jason D Whitt,J Bart Rose,Herbert Chen

doi:10.3390/molecules25214940

Abstract

In an effort to discover viable systemic chemotherapeutic agents for neuroendocrine tumors (NETs), we screened a small library of 18 drug-like compounds obtained from the Velu lab against pulmonary (H727) and thyroid (MZ-CRC-1 and TT) neuroendocrine tumor-derived cell lines. Two potent lead compounds (DHN-II-84 and DHN-III-14) identified from this screening were found to be analogs of the natural product makaluvamine. We further characterized the antitumor activities of these two compounds using pulmonary (H727), thyroid (MZ-CRC-1) and pancreatic (BON) neuroendocrine tumor cell lines. Flow cytometry showed a dose-dependent increase in apoptosis in all cell lines. Induction of apoptosis with these compounds was also supported by the decrease in myeloid cell leukemia-1 (MCL-1) and X-chromosome linked inhibitor of apoptosis (XIAP) detected by Western blot. Compound treatment decreased NET markers chromogranin A (CgA) and achaete-scute homolog 1 (ASCL1) in a dose-dependent manner. Moreover, the gene expression analysis showed that the compound treatment reduced c-Kit proto-oncogene expression in the NET cell lines. Induction of apoptosis could also have been caused by the inhibition of c-Kit expression, in addition to the known mechanisms such as damage of DNA by topoisomerase II inhibition for this class of compounds. In summary, makaluvamine analogs DHN-II-84 and DHN-III-14 induced apoptosis, decreased neuroendocrine tumor markers, and showed promising antitumor activity in pulmonary, thyroid, and pancreatic NET cell lines, and hold potential to be developed as an effective treatment to combat neuroendocrine tumors.

Highlights

Neuroendocrine tumors (NETs) have the fastest growing incidence rate in the United States, while representing 0.5% of all malignancies [1,2]
Our results show that the compounds DHN-II-84 and DHN-III-14 decrease c-Kit message and protein expression at low micromolar concentrations, suggesting this as a possible mechanism for their oncotoxicity
DHN-II-84 and DHN-III-14, were identified as potent lead compounds from this screening

Summary

Introduction

Neuroendocrine tumors (NETs) have the fastest growing incidence rate in the United States, while representing 0.5% of all malignancies [1,2]. They arise from chromaffin cells that are found throughout the body; NETs have a wide organ distribution [3]. Molecules 2020, 25, 4940 carcinoid syndrome include flushing, diarrhea, abdominal pain and palpitations [4,5]. Carcinoid syndrome can develop in patients with pulmonary NETs, which account for about 5–8% of syndrome include flushing, diarrhea, abdominal pain and palpitations [4,5]

Methods

Discussion

Conclusion