Anticancer activity of caffeic acid n‑butyl ester against A431 skin carcinoma cell line occurs via induction of apoptosis and inhibition of the mTOR/PI3K/AKT signaling pathway
Authors: Yiping Wu
Tang Hongbo
Min Wu
Ning Zeng
Yi Xu
Journal: Molecular Medicine Reports (2018)
Discipline: CLINICAL MEDICINE
Keywords: Skin cancer; mortality; treatment options; caffeic acid n‑butyl ester (CAE); A431 cell line
Affiliations: Department of Plastics and Aesthetic Surgery, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, P.R. China.

Abstract:  Skin cancer is one of the primary causes of mortality worldwide. With an increasing frequency of skin cancers, there is an urgent requirement for the development of numerous treatment options. The present study investigated the anticancer activity of caffeic acid n‑butyl ester (CAE) against the A431 skin cancer cell line. Antiproliferative effects were investigated using an MMT assay. Apoptosis was examined by DAPI and Annexin V/fluorescein isothiocyanate and propidium iodide staining. Reactive oxygen species (ROS), mitochondrial membrane potential (MMP) and cell cycle analyses were performed via flow cytometry. Protein expression was determined by western blotting. The findings of the present study demonstrated that among a variety of cancer cell lines, CAE exhibited significant anticancer activity against the A431 skin cancer cell line with a half‑maximal inhibitory concentration of 20 µM. CAE was associated with apoptosis and cell cycle arrest of A431 cells, and induced ROS‑mediated alterations in MMP. In addition, CAE considerably suppressed the expression of some of the important proteins of the phosphoinositide 3‑kinase (PI3K)/protein kinase B (AKT)/mechanistic target of rapamycin (mTOR) cascade. The results of the present study indicated that CAE exerted anticancer effects on the A431 skin carcinoma cell line via the induction of apoptosis and suppression of the PI3K/AKT/mTOR signaling pathway. Therefore, CAE may be beneficial for the development of chemotherapy for skin cancers. 

Retracted: Yes

PubPeer comments:
 *[left]* Figure 8 from [Zeng et al (2018)] .  Western blot analysis demonstrated the effect of indicated concentrations of CAE on expression of mTOR PI3K AKT signaling pathway proteins. *[right]* Figure 8 from [Fang et al (2019)] .  Effect of matricine on mTOR PI3K AKT signalling pathway at indicated concentrations of matricine. ![file] , 
 *[right]* Figure 4 from [Zeng et al (2018)] .  Effect of CAE on the protein expression of Bax and Bcl-2 was determined using western blot analysis. *[left]* Figure 7 from [He et al (2018)] .  Western blot analysis of the levels of mTOR P13K Akt pathway proteins showing that arglabin caused dose-dependent inhibition of p-mTOR, p-PI3K and p-AKT proteins. Bands are unidentified. ![file] A band is repeated and mirror-imaged. , 
 #1 Fig 4 again [right]. ![file] Green and rectangles marks bands also found in *[right]* Fig 7 from [Wang et al (2018b)] .  Effect of farnesol on the expression of PI3K Akt proteins in HeLa human cervical cancer cells. After treating the cells with 0, 10, 50 and 150 u00b5M dose of farnesol, the expression levels of different proteins were evaluated by western blot assay . *[left]* Fig 9 from [Wang et al (2018a)] .  Effect of boswellic acid on protein expression of PI3K AKT pathway in HCT-116 cells as indicated by western blotting . ![file] , 
 *[left]* Figure 4 from [Zeng et al (2018)] .  Effect of CAE on the protein expression of Bax and Bcl-2 was determined using western blot analysis *[right]* Figure 5 from [Yu et al (2017)] .  Expression of apoptosis-regulatory proteins in glioma U87 cells at indicated concentrations of globularifolin . ![file] , 
 *[left]* Figure 7 from [Zeng et al (2018)] .  Effects of CAE on the migration of A431 cells at indicated concentrations *[right]* Figure 7B from [Yu et al (2017)] .  Inhibition of cell migration and invasion of glioma cells at indicated concentrations of globularifolin. ... (B) globularifolin inhibited glioma U87 cell migration and invasion as tested by transwell assays. The migratory and invasive cells were detected by crystal violet staining and photographed . ![file] , 
 #4 More sightings. *[left]* Figure 6 from [Niu et al (2018)] .  Effect of cycloartenol on the Bax and Bcl-2 expression in glioma U87 cells as shown by western blotting . *[right]* Figure 7 from [He et al (2018)] .  Western blot analysis of the levels of mTOR P13K Akt pathway proteins showing that arglabin caused dose-dependent inhibition of p-mTOR, p-PI3K and p-AKT proteins. ![file] , 
 *[right]* Figure 6 from [Zeng et al (2018)] .  CAE triggers G2 M cell cycle arrest at indicated doses of CAE. *[left]* Figure 6 from [Ding Chen (2018)] .  The results of this flow cytometry Figure suggest that 20u03bcM of carbone led to G2 M cell cycle arrest of KMS-5 myeloma cell line. ![file] , 
 *[left]* Figure 2.  Induction of apoptosis by caffeic acid n-butyl ester at indicated concentrations as depicted by DAPI staining. *[right]* Figure 3A from [Zhang et al (2018)] .  Lactucopicrin-induced apoptosis in human SKMEL-5 human skin cancer cells. (A) DAPI staining at indicated concentrations. ![file] , 
 #7 *[middle]* Figure 6 from [Zeng et al (2018)] .  CAE triggers G2 M cell cycle arrest at indicated doses of CAE. *[left]* Figure 6 from [Ding Chen (2018)] .  The results of this flow cytometry Figure suggest that 20u03bcM of carbone led to G2 M cell cycle arrest of KMS-5 myeloma cell line. *[right]* Figure 6 from [Deng Li (2019)] .  Effect of linderalactone on the cell cycle phase distribution of A549 cells, as depicted by flow cytometry. ![file] , 
 Retracted [16 March 2021] .  An interested reader drew to our attention that, in the above paper, several of the figures appeared to contain strikingly similar data to those published in other articles by different authors from different research institutions, including (as examples) Fig. 8 (cf. Fig. 8 in Fang, K et al: u2018Antiproliferative effects of matricine in gemcitabine-resistant human pancreatic carcinoma cells are mediated via mitochondrial-mediated apoptosis, inhibition of cell migration, invasion suppression, and mammalian target of rapamycin (mTOR)-TOR PI3K AKT signalling pathwayu2019, Med Sci Monit 25: 2943-2949, 2019), Fig. 4 (cf. Fig. 7 in He, W et al: u2018Arglabin is a plant sesquiterpene lactone that exerts potent anticancer effects on human oral squamous cancer cells via mitochondrial apoptosis and downregulation of the mTOR PI3K Akt signaling pathway to inhibit tumor growth in vivou2019, J BUON 23: 1679-1685, 2018) and Fig. 7 (cf. Fig. 7B in Yu, Y et al: u2018Globularifolin exerts anticancer effects on glioma U87 cells through inhibition of Akt mTOR and MEK ERK signaling pathways in vitro and inhibits tumor growth in vivou2019, Biochemie 42: 144-151, 2017). The authors also independently informed the Editorial Office that they were unable to repeat the experiments shown in Fig. 4, and requested a retraction.  Given the overall problems that have come to light with this paper, the Editor of Molecular Medicine Reports has agreed with the authors that this article should be retracted from the publication. The Editor and the authors apologize for any inconvenience caused. ,