Objective: To determine the molecular mechanism by which absent in melanoma 2 (AIM2) induces breast cancer cell apoptosis.
Methods: Establish Tet-Off(TM) model system to induce AIM2 expression in great quantities, MCF-7 tTA-AIM2 cells were the experimental group; MCF-7 tTA-Luc cells were the control group. The expression and subcellular localization of AIM2 in breast cancer cell lines were determined via Western Blotting. AIM2 protein expression was determined after the addition of interferon-γ (102 U/ml). Flow cytometry was used to analyze the effects of AIM2 on the cell cycle. Apoptosis detection was performed by staining with Annexin V-FITC and propidium iodide. Apoptosis mechanism was detected via Western Blotting. The XTT assay was used to analyze the effects of AIM2 on cell growth.
Result: This experiment established Tet-Off guidance system. This system results which promotes AIM2 gene transcription and increased AIM2 protein expression. Four days after induction, AIM2 expression was detected. AIM2 expression increased with the number of days post-induction. AIM2 is present in cytoplasm and nuclei. Interferon-γ (102 U/ml) induced AIM2 protein expression and significantly increased AIM2 expression. AIM2 expression had no significant effect on the cell cycle, With the increase of Cdk2 expression induced by days were gradually increased, and Cdk4, Cyclin E expression was no significantly difference. AIM2 expression can significantly promote the apoptosis of breast cancer cells. Increased AIM2 expression can inhibit the expression of the anti-apoptotic protein Bcl-xL, increase the expression of the apoptosis proteins Bad and Bax, and activate caspases, resulting in cleavage of the DNA repair protein PARP. The XTT assay showed that AIM2 expression slows the rate of cell growth.
Conclusion: In this breast cancer Tet-Off(TM) system, AIM2 was expressed in the cytoplasm and nucleus, stimulated the mitochondria to promote apoptosis, and influenced cell survival and proliferation.
Keywords: Absent in melanoma 2; breast cancer cells; cell apoptosis; cell cycle; interferon-γ.