Erythro-austrobailignan-6 down-regulates HER2/EGFR/integrinβ3 expression via p38 activation in breast cancer.
BACKGROUND
Despite the benefits from different options of therapy for breast cancer, resistance of the disease to these therapies is rising and a novel agent is needed. Erythro-austrobailignan-6 (EA6) exhibits anti-cancer activity. However, the detailed anti-tumor mechanisms by which EA6 inhibits 4T-1 and MCF-7 cell growth have not been well studied.


OBJECTIVE
In this study, we investigated the anti-proliferative and anti-tumor properties of EA6 on breast carcinoma and its accompanying mechanisms.


METHODS
The cytotoxic and apoptotic effect of EA6 were measured in breast cancer cell lines of 4T-1 and MCF-7. The role of EA6 on cell proliferation and migration was examined by immunoblotting. The anti-tumor activity of EA6 was assessed in mice inoculated with 4T-1 breast cancer cells.


RESULTS
EA6 increased the number of Annexin V-positive apoptotic bodies and cleaved form of caspase-3 in a dose-dependent manner and phosphorylated JNK and p38 in both cells. Moreover, EA6 down-regulated cell cycle dependent proteins of CDK-4 and cyclin D1, and increased G0/G1 population in both cells. EA6-induced apoptosis is mediated by p38 MAPK and caspase-3 activation in both cells. EA6 significantly reduced HER2/EGFR/integrin β3 expression and Src phosphorylation, which was dependent on p38 MAPK activation in 4T-1 and MCF-7 cells. Furthermore, we confirmed the down-regulation of topoisomerases by EA6 treatment, but the overall effects of EA6 on topoisomerase isotype were cell type specific. Finally, EA6 (20mg/kg/day) significantly reduced mammary tumor volume in 4T-1 bearing mice by down-regulating HER2/EGFR/integrin β3 expression in tumor tissues.


CONCLUSIONS
Our results offer a novel insight into the mechanism of EA6-induced apoptosis in breast cancer cells. We propose that EA6 treatment resulted in the activation of p38 MAPK and caspase-3, which eventually participated in regulating apoptosis in 4T-1 and MCF-7 cells.
Department of Obstetrics & Gynecology, Graduate School of Oriental Medicine, Dongguk University, Gyeongju, Republic of Korea.
Jae-Hyun
JH
Han
Department of Biomedical Sciences, Center for Creative Biomedical Scientists at Chonnam National University, Gwangju, 61469, Republic of Korea.
Ha Jin
HJ
Jeong
Natural Product Bank of Korea Promotion Institute for Traditional Medical Industry, 94, Hwarang-ro, Gyeongsan-si, Gyeongsangbuk-do, Republic of Korea.
Han Na
HN
Lee
Natural Product Bank of Korea Promotion Institute for Traditional Medical Industry, 94, Hwarang-ro, Gyeongsan-si, Gyeongsangbuk-do, Republic of Korea.
Yun Ju
YJ
Kwon
Natural Product Bank of Korea Promotion Institute for Traditional Medical Industry, 94, Hwarang-ro, Gyeongsan-si, Gyeongsangbuk-do, Republic of Korea.
Heung-Mook
HM
Shin
Department of Biomedical Engineering, Dongguk University, Gyeonggi-do 10326, Republic of Korea.
Yura
Y
Choi
Department of Biomedical Engineering, Dongguk University, Gyeonggi-do 10326, Republic of Korea.
Seongmi
S
Lee
Department of Biomedical Engineering, Dongguk University, Gyeonggi-do 10326, Republic of Korea.
Seung Tack
ST
Oh
Department of Obstetrics & Gynecology, College of Korean Medicine, Dongguk University Ilsan Hospital, 27, Dongguk-ro, Siksa-dong, Ilsandong-gu, Goyang-si, Gyeonggi-do 10326, Republic of Korea. Electronic address: obgykdi@hanmail.net.
Dong-Il
DI
Kim
Department of Biomedical Sciences, Center for Creative Biomedical Scientists at Chonnam National University, Gwangju, 61469, Republic of Korea. Electronic address: jsong0304@dongguk.edu.
Songhee
S
Jeon
D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects / Q000235:genetics; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000235:genetics*; D045744:Cell Line, Tumor / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects / Q000235:genetics; D015536:Down-Regulation; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D017705:Lignans / Q000627:therapeutic use*; D061986:MCF-7 Cells / Q000187:drug effects*; D051379:Mice; D008517:Phytotherapy; D010936:Plant Extracts / Q000494:pharmacology* / Q000627:therapeutic use; D048051:p38 Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism*
D000970:Antineoplastic Agents; D017705:Lignans; D010936:Plant Extracts; D048051:p38 Mitogen-Activated Protein Kinases
Breast cancer; Caspase-3; EGFR; Erythro-austrobailignan-6, p38; Topoisomerase