Assessment of apoptosis and autophagy in oral squamous cell carcinoma cell line treated with salivary exosomes

Oral squamous cell carcinoma (OSCC) is a leading cause of cancer-related mortality worldwide. Salivary exosomes (sExosomes), a subtype of extracellular vesicles, have gained attention for their role in intercellular communication and their potential as non-invasive diagnostic and therapeutic tools. This study investigated the therapeutic effects of sExosomes on OSCC by examining cellular ultrastructure and assessing the expression of caspase-3 and the autophagy-related gene NKX2-3. Human OSCC cells (SCC-25) were cultivated in Dulbecco's Modified Eagle Medium (DMEM) containing 10% exosome-depleted fetal bovine serum (FBS) and 1% penicillin-streptomycin (PS). sExosomes were isolated from human saliva using differential ultracentrifugation and confirmed via transmission electron microscopy (TEM). The experiment included two groups: Group I (untreated OSCC cells) and Group II (OSCC cells treated with sExosomes for 14 days). Ultrastructural examination revealed abnormal mitotic figures, chromatin clumping, and enlarged mitochondria in Group I, whereas Group II showed features characteristic of apoptosis, including pyknotic nuclei, cytoplasmic vacuolization, and degenerated organelles. ELISA results indicated significantly higher caspase-3 levels in Group II (305.33) compared to Group I (91.03), suggesting enhanced apoptotic activity. Conversely, NKX2-3 expression was significantly lower in Group II (0.89) than in Group I (2.65), indicating suppression of autophagy-related signaling. Statistical analysis was conducted using an independent-samples t-test, with significance set at p < 0.05. These findings support the potential of sExosomes to modulate tumor behavior by promoting apoptosis and inhibiting autophagy in OSCC, underscoring their promise as novel therapeutic agents in future cancer treatment strategies.