Green tea and black tea inhibit proliferation and migration of HepG2 cells via the PI3K/Akt and MMPs signalling pathway

Black tea and green tea were produced via different processing techniques from the same tea leave variety. Then, biochemical components of the two water extracts were analysed to study cell apoptosis, migration and invasion of HepG2 cells induced by black tea and green tea. The monomer components of the black tea and green tea extracts were analysed by colorimetry and HPLC, with MTT assay and colony formation assays used to assess cell proliferation and viability. The effects of black tea and green tea on apoptosis of HepG2 cells were verified by flow cytometry, with wound healing and Transwell experiments used to detect cell invasion and metastasis. The expression of PI3K/Akt signalling and apoptosis-related proteins as well as epithelial-mesenchymal transition (EMT) regulatory factor in HepG2 cells were determined by western blotting after black tea and green tea treatment. Black tea and green tea extracts demonstrated different degrees of inhibition of cell migration and invasion, with green tea inducing more HepG2 cell apoptosis. In addition, green tea and black tea extracts inhibited the growth of HepG2 cells and induced apoptosis via PI3K/Akt, and inhibited cell migration and invasion through the MMPs signalling pathway. This study revealed the effects of fermented (black tea) and non-fermented tea (green tea) on liver cancer cells, providing a basis for the investigation of tea extracts for their anti-tumour potential.