Role of AMPK and Akt in triple negative breast cancer lung colonization

Abstract

Triple negative breast cancer (TNBC) is an aggressive disease with a 5-y relative survival rate of 11% after distant metastasis. To survive the metastatic cascade, tumor cells remodel their signaling pathways by regulating energy production and upregulating survival pathways. AMP-activated protein kinase (AMPK) and Akt regulate energy homeostasis and survival, however, the individual or synergistic role of AMPK and Akt isoforms during lung colonization by TNBC cells is unknown. The purpose of this study was to establish whether targeting Akt, AMPKα or both Akt and AMPKα isoforms in circulating cancer cells can suppress TNBC lung colonization. Transient silencing of Akt1 or Akt2 dramatically decreased metastatic colonization of lungs by inducing apoptosis or inhibiting invasion, respectively. Importantly, transient pharmacologic inhibition of Akt activity with MK-2206 or AZD5363 inhibitors did not prevent colonization of lung tissue by TNBC cells. Knockdown of AMPKα1, AMPKα2, or AMPKα1/2 also had no effect on metastatic colonization of lungs. Taken together, these findings demonstrate that transient decrease in AMPK isoforms expression alone or in combination with Akt1 in circulating tumor cells does not synergistically reduce TNBC metastatic lung colonization. Our results also provide evidence that Akt1 and Akt2 expression serve as a bottleneck that can challenge colonization of lungs by TNBC cells.

Vav1 Selectively Down-Regulates Akt2 through miR-29b in Certain Breast Tumors with Triple Negative Phenotype

“…Despite that a consensus regarding the isoform-specific functions of Akt was not reached even within a specific subtype of breast cancer, Akt2 was associated with tumor progression by increasing cell migration, invasion, and metastasis [ 9 , 10 ]. It was further demonstrated that Akt2 prevents apoptosis and promotes lung colonization of circulating TNBC cells [ 12 ]. With the aim to assess if the Vav1 dependent miR-29b/Akt2 relationship is involved in lung colonization of TNBC cells, MDA-MB-231 stably over-expressing Vav1, in which high miR-29b and low Akt2 levels correlated with reduced invasion capability in vitro, were injected into mice tail veins and evaluated for their ability to form lung tumors.…”

“…With the aim to assess if the Vav1 dependent miR-29b/Akt2 relationship is involved in lung colonization of TNBC cells, MDA-MB-231 stably over-expressing Vav1, in which high miR-29b and low Akt2 levels correlated with reduced invasion capability in vitro, were injected into mice tail veins and evaluated for their ability to form lung tumors. The evidence that none of the mice receiving cells over-expressing Vav1 developed lung aggregates of breast tumor cells suggests a protective role of the Vav1-induced miR-29b against the facilitation of extravasation of tumor cells into lung parenchyma, which was proposed to correlate with Akt2 [ 12 ]. Moreover, our finding that Akt2 expression but not phosphorylation is down-modulated by Vav1 in MDA-MB-231 cells [ 20 ], supports the evidence that Akt2 facilitates TNBC lung colonization independent of its activity [ 12 ].…”

“…The evidence that none of the mice receiving cells over-expressing Vav1 developed lung aggregates of breast tumor cells suggests a protective role of the Vav1-induced miR-29b against the facilitation of extravasation of tumor cells into lung parenchyma, which was proposed to correlate with Akt2 [ 12 ]. Moreover, our finding that Akt2 expression but not phosphorylation is down-modulated by Vav1 in MDA-MB-231 cells [ 20 ], supports the evidence that Akt2 facilitates TNBC lung colonization independent of its activity [ 12 ]. This phenomenon, attributed to the eventual compensatory phosphorylation of the other Akt isoforms present within the cells or to a non-kinase function of Akt2, confirmed the need to identify molecules capable of specifically inhibiting the individual Akt isozymes.…”

“…The Akt family includes three members (Akt1, Akt2 and Akt3) that play distinct roles in breast cancer malignancy, being Akt1 correlated with proliferation of tumor cells and the other two isozymes variously involved in invasion/metastasis [ 9 , 10 , 11 ]. In tumors with a triple negative phenotype, Akt2 has a crucial role in metastasis by regulating the epithelial-to-mesenchymal-transition (EMT) and by enabling extravasation through the vessel wall [ 12 ]. Furthermore, the silencing of Akt2 in triple negative breast tumor cells reduces the population and the metastatic potential of cancer stem cells (CSCs) [ 13 , 14 , 15 ].…”

Neutrophil Survival Signaling During Francisella tularensis Infection

“…In our hands, pretreatment of neutrophils 1 μM MK-2206 had no discernable effect on the rate of neutrophil apoptosis in the presence or absence of LVS as judged by flow cytometry ( Figure 6A ). As the effects of MK-2206 can be transient ( Will et al., 2014 ; Johnson et al., 2021 ), we also tested the newer and more potent AKT inhibitor, Afuresertib ( Yamaji et al., 2017 ). Consistent with the aforementioned data, pretreatment with 10 μM Afuresertib had no significant effect on the lifespan of neutrophils infected with LVS, but significantly reduced the rate of apoptosis of the uninfected cells at 18 and 24 hours ( Figure 6B ).…”