Head and neck squamous cell carcinoma (HNSCC) claims the lives of over 2,500 Australians each year. Treatment options often affect the ability to speak, swallow and breath. Improved diagnostic, therapeutic and prognostic modalities are needed to improve patient outcomes. MicroRNA are small regulatory proteins that have been recently implicated in the carcinogenesis of several cancer sub-types. Little is known regarding the role that these nucleic acids may play in the HNSCC due to the infancy of research in this field.
The aim of this project was to investigate the role that microRNA may have on experimental HNSCC cell lines by restoring deficient microRNA and assessing the effect on the cellular molecular biology. Several potential microRNA candidates were integrated into a viral delivery system and reintroduced into experimental HNSCC cell lines. Using western blotting, the expression of oncologically significant proteins could be determined in these transduced cell lines. Changes in the phenotype of the cell were also examined using functional analysis with cell growth assays, soft agar invasion, invasion matrix chambers, cell cycle analysis and cisplastin cell growth assays.
Each of the chosen three HNSCC cell lines were successfully transduced with four different candidate microRNA’s. After the transduction of the microRNA-342 a statistically significant change in the expression of the cell cycle regulator cyclin D1 could be detected on western blotting in the FaDu cell line. Cyclin D1 is responsible for the inactivation of the retinoblastoma protein. Following transduction of microRNA-342 higher levels of activate retinoblastoma protein were found in this cell line. This result was conducted in duplicate and demonstrated consistent results. A functional analysis of the FaDu cell line showed that compared to the negative controls, the cell line was 40.6% more sensitive to the chemotherapy agent cisplatin.
This research project has demonstrated that microRNA may be a contributor to the carcinogenesis of HNSCC. The significant alterations seen in the molecular biology of HNSCC in vitro with the FaDu cell line require validation in other experimental cell lines. If this can be demonstrated, then microRNA-342 has the potential for future diagnostic and therapeutic applications.