Head and neck squamous cell carcinomas (HNSCCs) are one of the most frequently detected cancers in the world; not all mechanisms related to the expression of keratin in this type of cancer are known. The aim of this study was to evaluate type II cytokeratins (KRT): KRT6A, KRT6B, and KRT6C protein concentrations in 54 tumor and margin samples of head and neck squamous cell carcinoma (HNSCC). Moreover, we examined a possible association between protein concentration and the clinical and demographic variables. Protein concentrations were measured using enzyme-linked immunosorbent assay (ELISA). Significantly higher KRT6A protein concentration was found in HNSCC samples compared to surgical margins. An inverse relationship was observed for KRT6B and KRT6C proteins. We showed an association between the KRT6C protein level and clinical parameters T and N in tumor and margin samples. When analyzing the effect of smoking and drinking on KRT6A, KRT6B, and KRT6C levels, we demonstrated a statistically significant difference between regular or occasional tobacco and alcohol habits and patients who do not have any tobacco and alcohol habits in tumor and margin samples. Moreover, we found an association between KRT6B and KRT6C concentration and proliferative index Ki-67 and HPV status in tumor samples. Our results showed that concentrations of KRT6s were different in the tumor and the margin samples and varied in relation to clinical and demographic parameters. We add information to the current knowledge about the role of KRT6s isoforms in HNSCC. We speculate that variations in the studied isoforms of the KRT6 protein could be due to the presence and development of the tumor and its microenvironment. It is important to note that the analyses were performed in tumor and surgical margins and can provide more accurate information on the function in normal and cancer cells and regulation in response to various factors.

Head and neck squamous cell carcinoma (HNSCC) is the sixth most prevalent type of cancer worldwide. Not all mechanisms associated with cell cycle disturbances have been recognized in HNSCC. The aim of this study was to examine the concentration of CDKN2A and Ki-67 proteins in 54 tumor and margin samples of HNSCC and to evaluate their association with the clinical and demographic variables. The ELISA method was used to measure concentrations of CDKN2A and Ki-67 in the tissue homogenates. A significantly higher CDKN2A concentration was found in OSCC tumor samples as compared with OPSCC+HPSCC+LSCC. An inverse correlation was observed for Ki-67. We showed an association between the CDKN2A level and the clinical parameters N in tumors. The patients with concomitant diseases had significantly higher levels of Ki-67 as compared with patients with no concomitant diseases. An analysis of the effect of drinking habits on Ki-67 level demonstrated a statistical difference between regular or occasional users of stimulants and patients who do not use any stimulants in the tumor and margin samples. Moreover, we found an association between CDKN2A and Ki-67 concentrations and the HPV status in tumor and margin samples. The levels of the proteins tested may be dependent on environmental factors. Our results showed that changes in protein levels in HNSCC subtypes may reflect different molecular pathways of tumor development or may also be responsible for the involvement of CDKN2A and Ki-67 in the carcinogenesis process.