Immunohistochemical examination of the immunreactivity of suprabasin, isthmi̇n-1 and podocalyxin in actinic keratosis and squamous cell carcinoma

The aim of this study was to immunohistochemically investigate the immunoreactivities of Isthmin-1 (ISM-1), Podocalyxin (PODXL) and Suprabasin (SBSN) in lesional skin samples of patients with Actinic Keratosis (AK) and Squamous Cell Carcinoma (SCC). A total of 60 tissue samples were used from the archives of the Department of Pathology, including 20 skin tissue samples diagnosed with AK, 20 skin tissue samples diagnosed with SCC, and 20 healthy skin tissue samples with no pathology found adjacent to the diseased tissue to form the control group. Tissue samples from patients diagnosed with other dermatological diseases or malignancies and those with diabetes mellitus were not included in the study. After confirming the diagnoses of the obtained skin samples, indirect immunohistochemical staining was performed for PODXL, ISM-1 and SBSN on tissue sections of 5-6 µm thickness taken from paraffin blocks. With this method, tissues incubated with primary antibody in a humid environment were incubated with biotinylated secondary antibody and incubation was performed with streptavidin enzyme (peroxidase or alkaline phosphatase) and enzyme substrate 3-Amino-9-Ethylcarbazole (AEC) or 3, 3'-diaminobenzidine (DAB) chromogens were applied. A histoscore was created by taking the prevalence (0.1: <25%, 0.4: 26-50%, 0.6: 51-75%, 0.9: 76-100%) and severity (0: none, +0.5: very little, +1: little, +2: moderate, +3: severe) of immunoreactivity in staining as criteria. Histoscore = prevalence x severity formula was used in calculations. The obtained data were analyzed using the statistical package for the social sciences (SPSS, version 22.0) (Chicago, IL, USA) package program. After the Kolmogorov-Smirnov and Shapiro-Wilk normality tests, independent sample t-test was used for variables with two groups and analysis of variance (ANOVA) was used for variables with more than two groups. The value of p<0.05 was considered statistically significant. In this study, the mean PODXL histoscores of the AK patient group, SCC patient group and control group were found to be 0.31; 0.9; 1.24 (respectively). This difference was found to be statistically significant (p<0.001). The mean ISM-1 histoscores of the AK patient group, SCC patient group and control group were found to be 0.19; 0.82; 2.61 (respectively). This difference was found to be statistically significant (p<0.001). The mean SBSN histoscores of the AK patient group, SCC patient group and control group were found to be 0.19; 0.8; 0.6 (respectively). This difference was found to be statistically significant (p<0.001). In conclusion, PODXL, ISM-1 and SBSN are important molecules in the diagnosis, treatment and management of AK and SHK. However, further studies are needed in the future to better understand the potential medical importance of these molecules and to better elucidate the contradictory situations. Keywords: Actinic keratosis, squamous cell carcinoma, isthmin-1, suprabasin, podocalyxin