A loss of profilin‐1 in late‐stage oral squamous cell carcinoma
TMSB4 is found at high levels in saliva in adults and even higher levels in neonatal saliva, which seems to indicate high expression in at least some tissues of the oral cavity. TMSB4 is the most abundant form of the multifunctional beta‐thymosin proteins that include TMB4, B10, and B15. The 43 amino acid TMB4 protein is believed to be the main actin‐sequestering protein, and there is evidence that it plays a role in regulating cell motility. In addition, the protein has roles in influencing angiogenesis, inflammation, cell survival, wound healing, and calcium deposition 14. There is evidence that TMSB4, a protein expressed at high levels in embryonic tissues, plays a role in expression of stem cell properties, and it is postulated that enrichment in some tumor types is linked to acquisition of embryonic cell properties or metastasis and tissue invasion. For example, TMSB4 is linked to metastatic spread of various malignancies, such as colorectal and breast 15 although enhanced expression most significantly occurs on the cancer border in stromal tissue and not in tumor cells themselves. In fact, in hepatocellular carcinoma, TMSB4 has been noted to be poorly expressed in the majority of tumor tissue while easily detected in normal parenchyma. Additionally, the protein is totally absent in hepatocellular tumor cells undergoing stromal invasion 15. In general, its expression seems to counter differentiation, and because TMSB4 is found at elevated levels in several tumor types, it is thought to work as an oncogene but its effects are also likely related to an altered stromal microenvironment 17.
We used brush oral cytology to ascertain variability of the mRNAs encoding PFN1 and TMSB4 proteins between different OSCC tumors. If these proteins closely linked to tumor progression vary on the RNA level in OSCC epithelium, we reckoned that they may also vary on the protein level.