Modulation of membrane properties of lung cancer cells by azurin enhances the sensitivity to EGFR-targeted therapy and decreased β1 integrin-mediated adhesion

Abstract

In lung cancer, the Epidermal Growth Factor Receptor (EGFR) is one of the main targets for clinical management of this disease. The effectiveness of therapies toward this receptor has already been linked to the expression of integrin receptor subunit β1 in NSCLC A549 cells. In this work we demonstrate that azurin, an anticancer therapeutic protein originated from bacterial cells, controls the levels of integrin β1 and its appropriate membrane localization, impairing the intracellular signaling cascades downstream these receptors and the invasiveness of cells. We show evidences that azurin when combined with gefitinib and erlotinib, tyrosine kinase inhibitors which targets specifically the EGFR, enhances the sensitivity of these lung cancer cells to these molecules. The broad effect of azurin at the cell surface level was examined by Atomic Force Microscopy. The Young 's module (E) shows that the stiffness of A549 lung cancer cells decreased with exposure to azurin and also gefitinib, suggesting that the alterations in the membrane properties may be the basis of the broad anticancer activity of this protein. Overall, these results show that azurin may be relevant as an adjuvant to improve the effects of other anticancer agents already in clinical use, to which patients often develop resistance hampering its full therapeutic response.

Bacterial azurin in potential cancer therapy

“…7 Will azurin be a better and more effective drug in cancer therapy if its lack of toxicity but significant efficacy in clinical trials in cancer patients can be demonstrated? This paper by Bernardes et al 1 in this issue of Cell Cycle is a significant step toward this direction.…”

“…A paper by Nuno Bernardes et al 1 entitled "Modulation of membrane properties of lung cancer cells by azurin enhances the sensitivity to EGFR-targeted therapy and decreased b1 integrin mediated adhesion" in this volume of Cell Cycle aims to gain a better understanding about the mechanism of action of azurin as a therapeutic protein for cancer treatment. Prior to this publication, Dr. Fialho's group reported that azurin targets P-cadherin overexpression in a subset of breast cancer, antagonizing its pro-invasive effects.…”

Azurin interaction with the lipid raft components ganglioside GM-1 and caveolin-1 increases membrane fluidity and sensitivity to anti-cancer drugs

“…Azurin is a protein from bacterial origin (Pseudomonas aeruginosa) which in the last years has been studied as an anticancer agent. We and others have identified different modes of action that account for the therapeutic effects of both the entire protein and one lead peptide, p28 [1][2][3][4][5]. The 28 amino acid sequence was first identified as the domain responsible for the penetration of azurin into cancer cells [6] and further studied as an anticancer peptide.…”

“…Research with azurin or the derived peptide in the past years have demonstrated that a number of signaling pathways associated with tumor progression and angiogenesis, such as FAK/Src or PI3K/Akt signaling are attenuated after treatment in several cancer models [3,5,13]. Also, functional evidences associated to adhesion to extracellular matrices, invasion and migration of cells are also weakened [5,14], linking the cellular responses to azurin to its possible effects at lipid rafts, which may act as the main gate of azurin to cancer cells.…”

“…Research with azurin or the derived peptide in the past years have demonstrated that a number of signaling pathways associated with tumor progression and angiogenesis, such as FAK/Src or PI3K/Akt signaling are attenuated after treatment in several cancer models [3,5,13]. Also, functional evidences associated to adhesion to extracellular matrices, invasion and migration of cells are also weakened [5,14], linking the cellular responses to azurin to its possible effects at lipid rafts, which may act as the main gate of azurin to cancer cells. Moreover, binding to both caveolin-1 and GM-1, structural components of caveolae/lipid rafts, is strongly associated to hydrophobic enriched regions in the binding partners [15,16], and azurin harbours in its tertiary structure two sheets arranged around an hydrophobic core region with the particular characteristic of being exposed and available for interactions [17].…”