Differences in the starvation-induced autophagy response in MDA-MB-231 and MCF-7 breast cancer cells

Abstract

Breast cancer is a heterogeneous disease with distinct subtypes that have made targeted therapy of breast cancer challenging. Previous studies have demonstrated that an altered autophagy capacity can influence the development of breast cancer. However, the molecular differences in starvation-induced autophagic responses in MDA-MB-231 and MCF-7 cells have not been fully elucidated. In this study, we found that an increase of LC3B-II protein expression level and a decrease of the p62 protein expression level in both cells treated by Earle’s balanced salt solution. Meanwhile, we observed an increase of autophagosome using transmission electron microscopy and an enhancement in the green fluorescence intensity of LC3B protein by confocal microscopy. Furthermore, we detected the expression of 13 autophagy-related (ATG) genes and 11 autophagy signaling pathway-related genes using qPCR. Among 13 ATG genes, we found that 6 genes were up-regulated in treated MDA-MB-231 cells, while 4 genes were up-regulated and 1 gene was down-regulated in treated MCF-7 cells. In addition, among 11 autophagy signaling pathway-related genes, 7 genes were up-regulated in treated MDA-MB-231 cells, while 5 genes were up-regulated and 1 gene was down-regulated in treated MCF-7 cells. These findings suggest that the autophagic response to starvation was different in the two treated cell lines, which will contribute to further study on the molecular mechanism of starvation-induced autophagy and improve the targeted therapy of breast cancer.

The Autophagy Machinery Contributes to E-cadherin Turnover in Breast Cancer

“…SQSTM1/p62, an autophagy receptor that interacts with autophagic substrates and LC3B and that is itself an autophagic target (Johansen and Lamark, 2011), diminished upon starvation and accumulated when autophagy was blocked (Supplementary Figures 2B-D). The magnitude of autophagy modulation varied in the different cell models, a finding that is keeping with the reported differences in the response to autophagy of breast cancer cell lines (Maycotte et al, 2014;Zhu et al, 2017).…”

β-Arrestin inhibition induces autophagy, apoptosis, G0/G1 cell cycle arrest in agonist-activated V2R receptor in breast cancer cells

“…The displacement of Bcl-2 from Beclin-1 and Bax, may be the driving force that triggered both autophagy and apoptosis [22]. In similar work, starved MDA MB-231 cells developed autophagy through the AMBRA1/mTOR pathway leading to an increase of LC3II, increase of autophagosomes but decrease of p62 protein [23]. The PI3K inhibitor (Wort) is commonly used as an autophagy inhibitor, based on its inhibitory effect on class III PI3K activity, which is known to be essential for induction of autophagy.…”

Inhibition of FOXO1‑mediated autophagy promotes paclitaxel‑induced apoptosis of MDA‑MB‑231 cells

“…Immunofluorescence. For detecting lc3, Mda-MB-231 cells were pretreated with Baf A1 (0 and 10 nM) at 37˚C, 5% CO 2 for 24 h and then treated with or without 20 nM PTX at 37˚C, 5% CO 2 for 24 h. cells were treated with 0, 10 and 30 nM PTX combined with or without 5 nM 3-methyladenine (3-Ma; 5 nM; a Pi3K inhibitor that is a widely used inhibitor of autophagy via its inhibitory effect on class III PI3K) at 37˚C, 5% CO 2 for 24 h. For detecting FoXo1, Mda-MB-231 cells were treated with 0, 10 and 20 nM PTX at 37˚C, 5% CO 2 for 24 h. Immunofluorescence analysis of light chain 3 (LC3) and FoXo1 proteins was performed as described in our previous study (17). In brief, the treated cells were fixed in 95% methanol at room temperature for 10 min and blocked in a buffer containing 1% BSA (cat.…”