Epithelial-to-mesenchymal transition status correlated with ultrastructural features, and TP53 mutation in patient-derived oral cancer cell lines.

BACKGROUND

Oral Squamous Cell Carcinoma (OSCC) is a highly prevalent cancer in the Indian subcontinent. The major cause of mortality in OSCC patients is metastasis. Epithelial-to-mesenchymal transition (EMT) marks an important step in the metastatic process. Additionally, TP53, an important tumor suppressor gene, is also a significant determinant of the treatment outcome, and also plays a role in EMT. Therefore, understanding the interconnections between ultrastructural features, EMT status and TP53 mutational status is of vital importance.

METHODS AND RESULTS

The ultrastructure of five OSCC cell lines was visualized by transmission electron microscopy. Trans-well invasion and migration assays as well as scratch-wound assay, and the expression of various EMT-related genes were utilized to assess the EMT status of the cell lines. The TP53 exons were amplified for the ACOSC3, ACOSC4 and ACOSC16 cell lines and sequenced and the mutations in the gene were identified by sequence alignment. The TP53 mutation in the UPCI:SCC029B cell line has been previously reported, while UPCI:SCC040 has been reported to harbor a wild type TP53. The ACOSC4 cell line which showed the shortest intercellular gaps, also had the least invasive and migratory potential. Interestingly, ACOSC4 showed the highest expression of E-cadherin and the lowest expression of Vimentin, TWIST1, ZEB1, and MMPs. Additionally, TP53 gene of ACOSC4 was unmutated, whereas the ACOSC3 and ACOSC16 harbored TP53 mutations. The mutation in ACOSC3 (R196*) was also found in 7 TCGA samples. Similarly, the UPCI:SCC040 cell line that harbors a wild type TP53 showed shorter intracellular gaps.

CONCLUSIONS

Cellular migratory properties are associated with cellular ultrastructure, epithelial-to-mesenchymal transition status and the status of TP53 mutation in the genome.