J Cancer 2021; 12(1):76-88. doi:10.7150/jca.47553

Research Paper

Shikonin inhibits migration and invasion of triple-negative breast cancer cells by suppressing epithelial-mesenchymal transition via miR-17-5p/PTEN/Akt pathway

Chang Bao2,3,4, Tao Liu5, Lingbo Qian1, Chi Xiao1, Xinru Zhou1, Heng Ai1, Jue Wang1, Weimin Fan2,3,4,6, Jie Pan1✉

1. School of Basic Medical Sciences & Forensic Medicine, Hangzhou Medical College, No.481 Binwen Road, Hangzhou 310053, People's Republic of China.
2. Program of Innovative Cancer Therapeutics, Division of Hepatobiliary and Pancreatic Surgery, Department of Surgery, First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou 310003, People's Republic of China.
3. Key Laboratory of Organ Transplantation, Hangzhou 310003, People's Republic of China.
4. Key Laboratory of Combined Multi-organ Transplantation, Ministry of Public Health, Hangzhou310003, People's Republic of China.
5. Department of Respiratory Medicine, Hospital of Traditional Chinese Medicine of Pingxiang city, No.10 Pingchuxi Road, Pingxiang 337000, People's Republic of China.
6. Department of Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston, SC 29425, USA.

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Bao C, Liu T, Qian L, Xiao C, Zhou X, Ai H, Wang J, Fan W, Pan J. Shikonin inhibits migration and invasion of triple-negative breast cancer cells by suppressing epithelial-mesenchymal transition via miR-17-5p/PTEN/Akt pathway. J Cancer 2021; 12(1):76-88. doi:10.7150/jca.47553. Available from https://www.jcancer.org/v12p0076.htm

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Background: Triple-negative breast cancer (TNBC) is a great threat to global women's health due to its high metastatic potential. Epithelial-to-mesenchymal transition (EMT) is considered as a key event in the process of metastasis. So the pharmacological targeting of EMT might be a promising strategy in improving the therapeutic efficacy of TNBC. Here, we investigated the effect of shikonin exerting on EMT and consequently the metastasis of TNBC cells and its underlying mechanism.

Methods: The invasive and migratory capacities of MDA-MB-231 and BT549 cells were tested using transwell invasion and wound healing assay. MiR-17-5p expression was examined by qRT-PCR. MiR-17-5p targeted genes were predicted with different bioinformatic algorithms from four databases (TargetScan, miRanda, PITA and picTar) and further screened by Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis. The differential expressions of predicted genes and their correlations with miR-17-5p were identified in breast cancer patients based on The Cancer Genome Atlas (TCGA) database. The interaction between phosphatase and tensin homolog deleted on chromosome ten (PTEN) and miR-17-5p was analyzed by luciferase reporter assay. The overexpression vector and small interfering RNA were constructed to investigate the role PTEN played in metastasis and EMT regulation. The expressions of EMT markers, protein kinase B (Akt) and phospho-Akt (p-Akt) were evaluated by western blot.

Results: Shikonin suppressed the migration and invasion of MDA-MB-231 and BT549 cells and meanwhile the corresponding alterations of EMT biomarkers were observed in shikonin treated MDA-MB-231 cells. Shikonin inhibited the expression of miR-17-5p, which was upregulated in breast cancer. The 3'-untranslated region (3'-UTR) of PTEN was found to be direct binding target of miR-17-5p by luciferase reporter assays. PTEN functioned as a suppressor both in the metastasis and EMT of TNBC cells. Moreover, Akt and p-Akt (Ser473) were involved in the process of inhibition in cancer cell migration, invasion and EMT by shikonin.

Conclusions: Shikonin inhibits migration and invasion of TNBC cells by suppressing EMT via miR-17-5p/PTEN/Akt pathway. This suggests shikonin as a promising therapeutic agent to counteract metastasis in the TNBC patients.

Keywords: Shikonin, Triple-negative breast cancer, Epithelial-to-mesenchymal transition, miR-17-5p, PTEN