Regulation of CD1, Ki-67, PCNA mRNA expression, and Akt activation in estrogen-responsive human breast adenocarcinoma cell line, MCF-7 cells, by griffonianone C, an isoflavone derived from Millettia griffoniana

Abstract

Context: Millettia griffoniana Baill. (Fabaceae), which contains isoflavonoids like griffonianone C (Griff C), is commonly used in the folk medicine in Cameroon to treat various ailments. Possible health benefits of Griff C which include alleviation of menopausal symptoms, limitation of bone resorption, and lowering of the risks of cancer and cardiovascular diseases attracted our interest.

Objective: The effects of Griff C on the regulation of the expression of proliferation markers such as proliferating cell nuclear antigen (PCNA), cyclin D1 (CD1) and Ki-67 are investigated here. Its role in apoptosis or cell survival, through the phosphatidylinositol 3 kinase-Akt (PI3K-Akt) signaling pathway is further studied.

Materials and methods: Semiquantitative real-time PCR was performed to analyze the effects of Griff C on gene expression in MCF-7 cells. Western blot analysis was used to assess the role of Griff C on the expression of phosphorylated Akt in MCF-7 cells.

Results: Griff C induced a 4.84-fold increase in the expression of Ki-67 mRNA at the concentration of 10⁻⁸ M and a 3.90-fold increase of CD1 mRNA at 10⁻⁷ M. Griff C slightly increased the phosphorylation of Akt at its serine 473 residue. Akt phosphorylation was inhibited by the PI3K inhibitor, LY294002, but not by the specific estrogen receptor antagonist, fulvestrant.

Discussion and conclusion: These findings suggest that Griff C can modulate proliferation of MCF-7 cells. Our results also suggest that Griff C can affect the PI3K-related signaling pathway. Thus, Griff C may exert part of its low proliferative and antiapoptotic effects by a nongenomic mode of action.

Keywords::

• Phytoestrogens
• real-time PCR
• gene expression regulation
• Akt
• western blot analysis