Abstract
Exosomes are membrane-bound nanovesicles released by cells into their extracellular environment. Exosomes influence cancer metastasis. The RNA levels of oncogenes within exosomes derived from cancer cells may thus provide a useful source for monitoring cancer progression and deploying early intervention.
To compare the RNA levels of FOXM1, DNMT1, HOXA7, CCNB1, and HSPA1A in exosomes from normal primary gingival keratinocyte (PGK) and oral squamous cell carcinoma (OSCC) cell lines.
Exosomes derived from PGK and OSCC cell lines (SCC4 and SCC25) were isolated using ultracentrifugation and their presence was confirmed by transmission electron cryomicroscopy. The exosomal RNA was extracted and subjected to reverse transcription quantitative polymerase chain reaction for mRNA analysis.
Transmission electron cryomicroscopy revealed bilayered structures measuring 50 to 200 nm, consistent with the expected size of exosomes. Transcripts for the genes of interest were detected in the OSCC cells (mean 2−ΔCT: 0.1563, 0.0111, 0.011, 0.1062, and 0.58, respectively) and exosomes (mean 2−ΔCT: 0.3564, 0.0036, 0.0458, 0.0718, and 0.7252, respectively). HOXA7 was not detected in PGK. Of the remaining genes of interest, more RNA was detected in the OSCC cells (mean fold upregulations of 4.44, 2.80, 2.28, and 2.90, respectively) and OSCC exosomes (mean fold upregulations of 6.33, 2.20, 3.16, and 5.75, respectively) when compared with the PGK cells and exosomes.
The results provide the first evidence that there is more FOXM1 and HSPA1A RNA in OSCC exosomes compared with PGK exosomes. These results will be used for ex vivo studies comparing exosomes in saliva and blood samples from patients with and without OSCC.