Interaction of Trastuzumab with biomembrane models at air-water interfaces mimicking cancer cell surfaces.

Trastuzumab (Tmab) is a monoclonal antibody administered as targeted therapy for HER2-positive breast cancer whose molecular interactions at the HER2 receptor microenvironment are not completely clarified yet. This paper describes the influence of Tmab in the molecular organization of films of biological-relevant molecules at the air water interface. For that, we spread components of tumorigenic and non-tumorigenic cells directly on the air-water interface. The physicochemical properties of the films were investigated with surface pressure-area isotherms and Brewster angle microscopy, and distinction between the cellular lines with higher or lower amount of HER2 could be detected based on the physicochemical properties of the interfacial films. The systems organized at the air-water interface were transferred to solid supports as Langmuir-Blodgett films and the nano-scale morphology investigated with atomic force microscopy. The overall results related to Tmab interacting with the films lead to the conclusion that Tmab tends to condense rich-HER2 films, causing irregular dimerization of the receptor protein, changing the membrane topography of the films, with formation of phases with different levels of reflectivity and aggregation morphology, and finally revealing that the interaction of the antibody with proteo-lipidic biointerfaces is modulated by the film composition. We believe that novel perspectives concerning the molecular interactions in the plasma membrane microenvironment through Langmuir monolayers can be obtained from this work in order to enhance the Tmab-based cancer therapy.

Acquisition of anoikis resistance promotes alterations in the Ras/ERK and PI3K/Akt signaling pathways and matrix remodeling in endothelial cells.

Anoikis is a programmed cell death induced upon cell detachment from extracellular matrix. Anoikis resistance is a critical mechanism in tumor metastasis. Cancer cells deregulate and adapt their metabolism to survive in the absence of adhesion, spreading metastases to distant organs. These adaptations include abnormal regulation of growth factor receptors activating prosurvival signaling pathways, such as the Ras/ERK and PI3K/Akt pathways, and extracellular matrix remodeling, leading to metastasis by an increase of invasiveness and inhibiting anoikis. This study investigates the possible involvement of ECM components and signaling pathways in the regulation of resistance to anoikis in endothelial cells (EC). Endothelial cells submitted to stressful conditions by blocking adhesion to substrate (anoikis resistance) display an up-regulation of Ras/ERK and PI3k/Akt pathways by high expression of Ras, ERK, PI3K (p110α) and Akt (Thr 308). After ERK and PI3K inhibiting, all EC-derived cell lines studied showed lower growth, a decrease in invasive potential and a higher rate of apoptosis. Furthermore, anoikis-resistant cell lines display a decrease in the expression of fibronectin, collagen IV and hyaluronic acid and an increase in the expression of laminin, perlecan, αv, ß3, α5 and ß1 integrins subunits, hyaluronidades 1, 2 and 3 and metalloproteinases 2 and 9. These results indicate that the acquisition of anoikis resistance induced remodeling of the extracellular matrix and overexpression of the PI3K/Akt and Ras/ERK pathway components. Acquisition of resistance to anoikis is a potentially crucial step in endothelial cell transformation.