Acquiring Metastatic Competence by Oral Squamous Cell Carcinoma Cells Is Associated with Differential Expression of α-Tubulin Isoforms

Abstract EN

We performed comparative global proteomics analyses of patient-matched primary (686Tu) and metastatic (686Ln) OSCC cells.

The metastatic OSCC 686Ln cells showed greater in vitro migratory/invasive potential and distinct cell shape from their parental primary 686Tu cells.

Ettan DIGE analysis revealed 1316 proteins spots in both cell lines with >85% to be quantitatively similar (<2 folds) between the two cell lines.

However, two protein spots among four serial spots were highly dominant in 686Ln cells.

Mass spectrometry sequencing demonstrated all four spots to be α-tubulin isotypes.

Further analysis showed no significant quantitative difference in the α-tubulin between the two cell lines either at mRNA or protein levels.

Thus, two distinct isoforms of α-tubulin, probably due to posttranslational modification, were associated with metastatic 686Ln cells.

Immunofluorescence demonstrated remarkable differences in the cytosolic α-tubulin distribution patterns between the two cells.

In 686Tu cells, α-tubulin proteins formed a normal network composed of filaments.

In contrast, α-tubulin in 686Ln cells exhibited only partial cytoskeletal distribution with the majority of the protein diffusely distributed within the cytosol.

Since α-tubulin is critical for cell shape and mobility, our finding suggests a role of α-tubulin isoforms in acquisition of metastatic phenotype and represents potential target for therapeutic intervention.