KRAS gene silencing inhibits the activation of PI3K-Akt-mTOR signaling pathway to regulate breast cancer cell epithelial-mesenchymal transition, proliferation and apoptosis

Y. Zhang, J.-L. Liu, J. Wang

Breast Department, Chui Yang Liu Hospital Affiliated to Tsinghua University, Beijing, P.R. China. drzhangying@163.com

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• Oncology

OBJECTIVE: Our study was performed to investigate the effect of KRAS gene silencing on epithelial-mesenchymal transition (EMT), proliferation, and apoptosis of breast cancer cells by mediating PI3K-Akt-mTOR signaling pathway.

MATERIALS AND METHODS: The positive rate of KRAS protein expression was detected in tissues collected from breast cancer patients, associated with the analysis of the relationship between KRAS protein expression and clinicopathological features of patients. The expression of KRAS in breast cancer cell lines was tested to screen the suitable cell line. After cell transfection and grouping, qRT-PCR and Western blot were then used to detect the mRNA and protein expression in each group. MTT assay and flow cytometry detected cell proliferation, cell cycle, and apoptosis, respectively.

RESULTS: The expression of KRAS in cancer tissue was much higher than that in paracancerous normal tissue, and its high expression was correlated statistically with lymph node metastasis, distant metastasis, and tumor infiltration level of patients (all p<0.05). KRAS was highly expressed in T47D and thus selected as suitable cell lines for subsequent analysis (all p<0.05). Compared with Blank group and NC group, there were significantly reduced mRNA and protein expression of KRAS, PI3K, Akt, mTOR, N-cadherin and Vimentin, increased PTEN and E-cadherin, decreased cell proliferation activity, and increased apoptosis in si-KRAS and Wortmannin groups (all p<0.05); while opposite trends were found in HA-KRAS group and Recilisib group (all p<0.05). However, there was no significant difference when compared si-KRAS+Recilisib with that in Blank and NC groups (all p>0.05).

CONCLUSIONS: Silencing of KRAS gene expression may inhibit the activation of PI3K-Akt-mTOR signaling pathway, and thus inhibit EMT, proliferation and apoptosis of breast cancer cells. By contrast, activation of the studied signaling pathway can reverse the positive effect of KRAS gene silencing.

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