Gold nanoparticle (AuNP)-based systems have been extensively investigated as diagnostic and therapeutic agents due to their tunable properties and easy surface functionalization. Upon cell uptake, AuNPs present an inherent cell impairment potential based on organelle and macromolecules damage, leading to cell death. Such cytotoxicity is concentration-dependent and completely undesirable, especially if unspecific. However, under non-cytotoxic concentrations, internalized AuNPs could potentially weaken cells and act as antitumor agents. Therefore, this study aimed to investigate the antitumor effect of ultrasmall AuNPs (∼3 nm) stabilized by the anionic polysaccharide gum arabic (GA-AuNPs). Other than intrinsic cytotoxicity, the focus was downregulation of cancer hallmarks of aggressive tumors, using a highly metastatic model of melanoma. We first demonstrated that GA-AuNPs showed excellent stability under biological environment. Non-cytotoxic concentrations to seven different cell lines, including tumorigenic and non-tumorigenic cells, were determined by standard 2D in vitro assays. Gold concentrations ≤ 2.4 mg L^-1 (16.5 nM AuNPs) were non-cytotoxic and therefore chosen for further analyses. Cells exposed to GA-AuNPs were uptaken by melanoma cells through endocytic processes. Next we described remarkable biological properties using non-cytotoxic concentrations of this nanomaterial. Invasion through an extracellular matrix barrier as well as 3D growth capacity (anchorage-independent colony formation and spheroids growth) were negatively affected by 2.4 mg L^-1 GA-AuNPs. Additionally, exposed spheroids showed morphological changes, suggesting that GA-AuNPs could penetrate into the preformed tumor and affect its integrity. All together these results demonstrate that side effects, such as cytotoxicity, can be avoided by choosing the right concentration, nevertheless, preserving desirable effects such as modulation of key tumor cell malignancy features.

The present review provides a comprehensive overview of the current state of in vitro cancer studies, focusing on recent advancements and ongoing in cell culture models and analyses techniques. Cancer cells grow in a complex and dynamic environment, interacting with various cellular components, such as stromal cells, cancer‐associated fibroblasts, immune cells, and the extracellular matrix (ECM). The ECM provides structural support and unique characteristics essential for tumorigenesis. Accurately modeling this intricate tumor microenvironment and precisely analyzing cell–cell and cell–ECM interactions are crucial for understanding cancer progression and therapeutic responses. Consequently, oncology research is advancing toward a) three‐dimensional tumor models, b) single‐cell level analyses, and c) live‐cell analyses. This review aims to elucidate current knowledge in this field, emphasizing the benefits these innovative approaches offer over traditional two‐dimensional models, bulk analyses, and endpoint measurements.

Polyoxovanadates are a subclass of polyoxometalates (POMs) known to interact with proteins and to present anticancer, antimicrobial, and antiviral activities. Herein, we aimed to pursue the study of the breast anticancer activity of a mixed-valence polyoxovanadate, [Cl@V^V₇V^IV₈O₃₆]⁶⁻ (V₁₅) against MCF-7 and MDA-MB-231 cancer cell lines and to analyze its Ca²⁺-ATPase inhibition potential. ⁵¹V NMR and UV-Vis/NIR studies of V₁₅ indicated its stability in HEPES and RPMI media. For the Ca²⁺-ATPase activity, V₁₅ showed an IC₅₀ value of 14.2 μM and a mixed type of inhibition. The electrostatic potential map of V₁₅ and other POMs were correlated with the enzyme activity inhibition. V₁₅ also exhibited cytotoxicity against MDA-MB-231 (IC₅₀ = 17.2 μM) and MCF-7 (IC₅₀ = 15.1 μM) breast cancer cell lines. Using V₁₅ concentrations equivalent to half and 1/4 of the IC_50, it was observed that MDA-MB-231 cell migration was reduced by 90 and 70%, after 24 h, respectively. Moreover, V₁₅ caused morphological changes from fusiform to an epithelial-like (amoeboid) shape. Finally, V₁₅ induced the increase in RIPK1, MLKL, and RIPK3 gene expression, up to 3, 10, and 15-fold, respectively, pointing out that the mechanisms of cell death in the triple-negative breast cancer cell line may occur by necroptosis.

Imagine the future where melanoma, one of the most lethal types of skin cancer, is not a frightful diagnosis anymore but a challenge met with tailored prec