Abstract
Phytoestrogen intake is known to be beneficial to decrease breast cancer incidence and progression. But its molecular mechanisms of action are still unknown. The present study aimed to examine the effect of apigenin on proliferation and apoptosis in HER2-expressing breast cancer cells. In our experiments, apigenin inhibited the proliferation of BT-474 cells in a dose- and time-dependent manner. Apigenin also inhibited clonogenic survival (anchorage-dependent and -independent) of BT-474 cells in a dose-dependent manner. These growth inhibitions were accompanied with an increase in sub-G0/G1 apoptotic populations. Apigenin-induced extrinsic a caspase-dependent apoptosis up-regulating the levels of cleaved caspase-8 and cleaved caspase-3, and inducing the cleavage of poly (ADP-ribose) polymerase (PARP). Whereas, apigenin did not induce apoptosis via intrinsic mitochondrial apoptosis pathway since this compound did not decrease mitochondrial membrane potential without affecting the levels of B-cell lymphoma 2 (Bcl-2) and Bcl-2-associated X protein (BAX). Apigenin reduced the expression of phospho-JAK1, phospho-JAK2 and phospho-STAT3 and decreased signal transducer and activator of transcription 3 (STAT3) dependent luciferase reporter gene activity in BT-474 cells. Apigenin inhibited CoCl2-induced VEGF secretion and decreased the nuclear translocation of STAT3. Our study indicates that apigenin induces apoptosis through inhibition of STAT3 signalling and could serve as a useful compound to prevent or treat HER2-overexpressing breast cancer.
Highlights
Phytoestrogens are a large group of plant-derived compounds and contain a phenolic ring which allows them to bind to the oestrogen receptor (ER), showing weak oestrogenic activity [1]
BT-474 cells were treated with apigenin (0–60 μM) for 24 h
We investigated the mechanism by which apigenin suppresses the growth of HER2-overexpressing breast cancer cells
Summary
Phytoestrogens are a large group of plant-derived compounds and contain a phenolic ring which allows them to bind to the oestrogen receptor (ER), showing weak oestrogenic activity [1]. Apigenin-induced growth inhibition and apoptosis in a variety of cancer cell lines including breast [15], lung [16], colon [17,18], prostate [19], leukaemia [20] and pancreatic [21] cells. These studies suggest that apigenin could be developed as a chemopreventive and/or chemotherapeutic agent for cancer
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