Polyphenol-rich extract of Salvia chinensis exhibits anticancer activity in different cancer cell lines, and induces cell cycle arrest at the G(0)/G(1)-phase, apoptosis and loss of mitochondrial membrane potential in pancreatic cancer cells

Pancreatic cancer (PC) is one of the most aggressive types of human malignancy, which has an overall 5-year survival rate of <2%. PC is the fourth most common cause of cancer-associated mortality in the western world. At present, there is almost no effective treatment available for the treatment of PC. The aim of the present study was to evaluate the anticancer potential of a polyphenol enriched extract obtained from Salvia chinensis, a Chinese medicinal plant. An MTT assay was used to evaluate the cell viability of five cancer cell lines and one normal cell line. In addition, the effects of the extract on apoptotic induction, cell cycle phase distribution, DNA damage and loss of mitochondrial membrane potential (ΛΨm) were evaluated in MiapaCa-2 human PC cells. The effects of the extract on cell cycle phase distribution and ΛΨm were assessed by flow cytometry, using propidium iodide and rhodamine-123 DNA-binding fluorescent dyes, respectively. Fluorescence microscopy, using 4′,6-diamidino-2-phenylindole as a staining agent, was performed in order to detect the morphological changes of the MiapaCa-2 cancer cells and the presence of apoptotic bodies following treatment with the extract. The results of the present study demonstrated that the polyphenol-rich extract from S. chinensis induced potent cytotoxicity in the MCF-7 human breast cancer cells, A549 human lung cancer cells, HCT-116 and COLO 205 human colon cancer cells, and MiapaCa-2 human PC cells. The COLO 205 and MCF-7 cancer cell lines were the most susceptible to treatment with the extract, which exhibited increased rate of growth inhibition. Fluorescence microscopy revealed characteristic morphological features of apoptosis and detected the appearance of apoptotic bodies following treatment with the extract in the PC cells. Flow cytometric analysis demonstrated that the extract induced G(0)/G(1) cell cycle arrest in a dose-dependent manner. In addition, treatment with the extract induced a significant and concentration-dependent reduction in the ΛΨm of the PC cells.