Apigenin induces caspase-dependent apoptosis by inhibiting signal transducer and activator of transcription 3 signaling in HER2-overexpressing SKBR3 breast cancer cells
Authors: Han-Seok Choi
Seong-Gyu Ko
Yong Cheol Shin
Jin Mo Ku
Hoyeon Go
Jong-Kyu Woo
Hye-Sook Seo
Bo-Hyoung Jang
Journal: Molecular medicine reports (2015)
Discipline: CLINICAL MEDICINE
Keywords: Phytoestrogens; apigenin; breast cancer; HER2; proliferation
Affiliations: Laboratory of Clinical Biology and Pharmacogenomics and Center for Clinical Research and Genomics, College of Korean Medicine, Kyung Hee University, Dongdaemun‑gu, Seoul 130‑701, Republic of Korea., College of Pharmacy, Gachon University of Medicine and Science, Yeonsu‑gu, Incheon 406‑840, Republic of Korea., Department of Oriental Medicine, Semyung University, College of Korean Medicine, Jecheon, Chungbuk 390‑711, Republic of Korea.

Abstract:  Phytoestrogens have been demonstrated to inhibit tumor induction; however, their molecular mechanisms of action have remained elusive. The present study aimed to investigate the effects of a phytoestrogen, apigenin, on proliferation and apoptosis of the human epidermal growth factor receptor 2 (HER2)-expressing breast cancer cell line SKBR3. Proliferation assay, MTT assay, fluorescence-activated cell sorting analysis, western blot analysis, immunocytochemistry, reverse transcription-polymerase chain reaction and ELISA assay were used in the present study. The results of the present study indicated that apigenin inhibited the proliferation of SKBR3 cells in a dose-and time-dependent manner. This inhibition of growth was accompanied by an increase in the sub-G0/G1 apoptotic population. Furthermore, apigenin enhanced the expression levels of cleaved caspase-8 and -3, and induced the cleavage of poly(adenosine diphosphate ribose) polymerase in SKBR3 cells, confirming that apigenin promotes apoptosis via a caspase-dependent pathway. Apigenin additionally reduced the expression of phosphorylated (p)-janus kinase 2 and p-signal transducer and activator of transcription 3 (STAT3), inhibited CoCl2-induced vascular endothelial growth factor (VEGF) secretion and decreased the nuclear localization of STAT3. The STAT3 inhibitor S31-201 decreased the cellular proliferation rate and reduced the expression of p-STAT3 and VEGF. Therefore, these results suggested that apigenin induced apoptosis via the inhibition of STAT3 signaling in SKBR3 cells. In conclusion, the results of the present study indicated that apigenin may be a potentially useful compound for the prevention or treatment of HER2-overexpressing breast cancer. 

Retracted: No

PubPeer comments:
 This paper is part of a set of papers, all from the Aix-Marseille Universitu00e9 Institut Hospitalo-Universitaire Mu00e9diterranu00e9e-Infection in Marseille, France, that all describe novel bacterial strains isolated in African countries, but without mentioning ethical approval by local authorities, and without local authors. In this paper, a novel bacterial species is described, isolated from the stool of a healthy 35y old pygmy woman in Congo. The article offers few details and some possible conflicting statements, so I hope the authors could answer some questions here. * What was the approximate place of residence of the subject? The text says samples were collected in Congo . Do the authors mean ([Republic of the Congo](http: en.wikipedia.org wiki Republic_of_the_Congo) or neighboring [Democratic Republic of the Congo](http: https: en.wikipedia.org wiki Democratic_Republic_of_the_Congo)? * Are there any details known about e.g. diet, living conditions (rural vs urban, agricultural vs. hunter gatherer) of the study subject?There is only limited value to describe a novel human-associated bacterial species if those details about the human host are not given. * The paper cites reference 1, DOI: 10.1128 CMR.00014-14 - but that is a review paper about culturomics and I could not find specific details about the study. Of note, the word Congo is not present in that paper. * Although the first paragraph of the paper states *Samples were collected in Congo* , the last paragraph of the paper says the strain was named after Marseille, where the bacterium was discovered. * The Genbank Entry LT623900 does not mention that the isolate came from a woman in Congo either. Rather it says that it was isolated in the hospital of Timone (Marseille). See: https: www.ncbi.nlm.nih.gov nuccore LT598582.1 * The link to the MALDI-TOF MS spectrum given in the paper does not seem to be working. I found this link for ALL spectra produced by the institute , but that leads to a downloadable zipped file with files with non-descriptive names such as  EG1 (D9).emf . * How did the authors manage to incubate the specimen in a blood culture bottle under anaerobic conditions? Some details appear to be missing. Was the sample transported from Congo back to France at some cold temperature, and then added to the blood culture bottle, or was the sample processed locally? Did local researchers or authorities participate? * The study mentions *This study was approved by the ethics committee of the Institut Federatif de Recherche IFR48 (Marseille, France) under number 09-022.* But that is a committee in France, not in one of the Congo republics. There is no word about obtaining IRB approval e.g. on consent wording with the local authorities. I could not find wording about consent obtained from the Pygmy woman either. In addition, the authors are from France and Lebanon, without any local researchers to contribute. Could the authors please explain how the research was being performed, and why local researchers were not given a chance to participate? How was this individual selected? ,