As one of the most abundant constituents of the tumour microenvironment (TME), cancer‐associated fibroblasts (CAF) display critical roles during tumour progression and metastasis. Multiple classes of molecules including growth factors, cytokines, proteases and extracellular matrix proteins, are produced by CAF to act as mediators of the stroma‐tumour interactions. One of the main channels for this communication is associated with extracellular vesicles (EV), which are secreted particles loaded with protein and genetic information. In this study, we evaluated the effects of EV derived from CAF primary human cell lines (n = 5) on proliferation, survival, migration, and invasion of oral squamous cell carcinoma (OSCC) cells. As controls, EV from human primary‐established normal oral fibroblasts (NOF, n = 5) were used. Our in vitro assays showed that CAF‐EV significantly induces migration and invasion of OSCC cells and promote a disseminated pattern of HSC‐3 cell invasion in the 3D organotypic assay. Furthermore, gene expression analysis of EV‐treated cancer cells revealed changes in the pathways associated with tumour metabolism and up‐regulation of tumour invasion genes. Our findings suggest a significant role of CAF‐EV in promoting the migration and invasion of OSCC cells, which are related to the activation of cancer‐related pathways.

The side-effects of many drugs manifest in the oral mucosa. The anti-malarial agent chloroquine diphosphate, which is also used to treat immunological, dermatological, and rheumatological disorders, usually causes pigmentary changes in the oral mucosa. This report presents a case of palate pigmentation related to the prolonged use of chloroquine diphosphate caused by the deposition of drug metabolites in the mucosa. Healthcare professionals must be aware of these drugs and their adverse effects in order to make the correct diagnosis, decide on the optimal treatment for the condition, or refer the patient to an appropriate specialist.