Document Type

Dissertation - Open Access

Award Date

2018

Degree Name

Doctor of Philosophy (PhD)

Department / School

Chemistry and Biochemistry

First Advisor

Fathi T. Halaweish

Keywords

Cucurbitacins, EGFR, Eriotnib, Hepatocellular carcinoma, HepG2 Resistant, MRP

Abstract

Hepatocellular carcinoma (HCC) is considered the third leading cause of death from cancer. Overall survival rate is significantly low, due to the emerging resistance to chemotherapeutic agents and lack of selectivity. Recent studies have demonstrated that epidermal growth factor receptor (EGFR) is a promising molecular target for cancer therapy, especially HCC. Current studies showed that cucurbitacins are potent anticancer compounds which target EGFR. This prompted us to investigate the antiproliferative activity of novel cucurbitacins inspired estrone analogs (CIEA) against sensitive and resistant HepG2 cell lines. Anti-proliferation activity of 20 CIEA analogs were examined against HepG2 using MTT assay and showed that antiproliferative activity of analogs MMA132, and MMA102 IC50 are 2μM, and 3 μM respectively in comparison to Erlotinib 25 μM. Study of the mechanism of anti-proliferation effects of these novel analogs was elucidated. Western blot analysis showed that MMA132, and MMA102 significantly inhibit EGFR/pEGFR, RAF/pRAF, MEK/pMEK, and ERK/PERK. Cell cycle analysis on HepG2 cell line revealed that MMA132 and MMA102 arrested the cells at G1 phase and inhibited the HepG2 cell migration after 24 hr. MMA132 induced apoptosis through activation of caspase 3,9 and inhibition of PARP. Treatment of HepG2-R (Erlotinib resistant) with MMA132 and MMA102 showed that these two novel drug candidates still possessing potent anti-proliferation activities against HepG2-R. Further characterization of the anti-proliferation of these lead compounds was demonstrated through mapping the change in EGFR signaling pathway (ERK, pERK, RAS, AKT and MEK) by western blot, cell cycle analysis, demonstrated that MMA132 and MMA102 stop the cell cycle of HepG2-R at G2 phase and inhibited cell migration after 48hrs. HepG2-R cell line significantly expressed MRP2 in comparing to sensitive cells. Moreover, MK571(MRP2 inhibitor) showed an inhibitory effect on resistant HepG2-R cancer cell lines. Combination of MMA132 with MK571 (13 μM and 15 μM respectively) showed a significant increase in the cytotoxicity of MK571 from 18.5 μM to 10 μM. In conclusion, our study documented the discovery of novel estrone analogs as potential drug candidates for treatment of HCC and promising chemotherapeutic agent toward HepG2 resistant to erlotinib.

Library of Congress Subject Headings

Liver -- Cancer.
Estrone.
Cucurbitaceae.
Epidermal growth factor -- Receptors.

Description

Includes bibliographical references

Format

application/pdf

Number of Pages

145

Publisher

South Dakota State University

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Included in

Biochemistry Commons

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Rights Statement

In Copyright