Nanoscale Integrin Ligand Patterns Determine Melanoma Cell Behavior

Abstract

Cells use integrin receptors to adhere onto surfaces by binding to ligands such as the arginine-glycine-aspartic acid (RGD) motif. Cancer cells make use of this adhesion process, which has motivated the development of integrin-directed drugs. However, those drugs may exert paradoxical effects on tumor progression, which raises the question of how integrin function is governed in tumor cells on the nanoscale. We have utilized precisely defined and tunable RGD ligand site densities spanning 1 order of magnitude, i.e., 103 to 1145 ligand sites/μm(2), by using RGD-functionalized gold nanoparticle patterns immobilized on glass by block copolymer (micellar) nanolithography. In an αVβ3 integrin-dependent fashion, human melanoma cells spread, formed focal contacts, and reorganized cytoskeletal fibers on a physiologically relevant RGD density of 349 sites/μm(2). Intriguingly, low doses of solute RGD "shifted" the optimal densities of immobilized ligand along with corresponding melanoma cell integrin clusters and cytoskeletal changes toward those typical for "intermediate" ligand presentation. Consequently, melanoma cells were forced into a "permissive" state, optimizing interactions with suboptimal nanostructured biomimetic surfaces, thus providing an explanation for the seemingly paradoxical effects on tumor progression and a potential clue for individualized antitumoral therapies.

Mechanochemical mechanism of integrin clustering modulated by nanoscale ligand spacing and rigidity of extracellular substrates

“…The MC model simulation results showed that integrin clustering decreased when the ligand spacing was larger than some threshold (~60nm), in good agreement with previous experimental results, which found that cell adhesion formed only if the ligand spacing was less than a particular threshold such as ~60nm [19][20][21][22][23][24][25]. As a matter of fact, the increase in the ligand spacing directly decreased the chance of active integrins during diffusion to bind to the underlying ligands and thus reduced the probability of integrin clustering.…”

“…Likewise, it has been experimentally revealed that the spacing of integrin ligands on two-dimensional flat matrices/substrates can essentially exert a strong impact on the formation and development of nascent adhesions that are the precursors of FAs [1,13]. Only on the premise that the underlying ligand spacing is smaller than some specific threshold such as ~60nm for rigid substrates in some experiments, cells begin to adhere and spread [16][17][18] with enhancement of initial adhesion strength [19][20][21][22], which is accompanied by an increase in integrin cluster size and density [23], then formation of stable FAs and actin cytoskeletons [24], and finally activation of cellular functions and signaling events [25]. Otherwise, it seems impossible for cells to cause integrin clustering and the occurrence of nascent FAs [1,13].…”

Biological responses to nanomaterials: understanding nano-bio effects on cell behaviors

“…It was concluded that certain functionalized nanoparticles promoted growth of specific cell lines while inhibiting others, due to the differences of cell sensitivity responding to the environment, which was explained precisely in their article. Another example is the work of Amschler et al (2014). They generated bioinspired surfaces by functionalization of AuNPs (ranging from 30 to 120 nm) with cyclic (RGDfE), a pentapeptide specific for the a V b 3 integrin.…”

Fabrication of Patterned Thermoresponsive Microgel Strips on Cell-Adherent Background and Their Application for Cell Sheet Recovery

“…[1][2][3][4][5] Among various engineered interfaces, the patterned surfaces in which adhesive islands located on a non-adhesive background have attracted much interest in recent years.…”