Investigation of the relationship between SATB2 expression and microsatellite instability in colon carcinomas

Colon adenocarcinoma is the most common malignancy of the gastrointestinal tract.It is an important cause of morbidity and mortality worldwide. Colon adenocarcinomas are responsible for approximately 10% of all cancer deaths in the world. The causes and pathogenesis of colon carcinomas are related to both genetic and environmental factors. Microsatellites are short repeating DNA sequences of base pairs in both coding and non-coding regions scattered throughout the human genome. Due to their repetitive nature, they are particularly prone to replication errors and are repaired by the mismatch repair (MMR) system. The MMR system includes proteins such as MLH- 1, PMS-2, MSH-2, MSH-6, MLH-3, MSH-3, PMS-1. These proteins form heterodimers that repair DNA damage. Deficiency of one of these proteins results in missing MMR (dMMR), microsatellite instability (MSI). The most common heterodimers in colorectal carcinogenesis are MLH-1/PMS-2 and MSH-2/MSH-6. SATB2 (Special AT-rich sequence binding protein) is a member of the transcription factor family that interacts with the AT-rich matrix binding site of DNA. It is expressed in epithelial cells of the lower gastrointestinal tract, including the colon and appendix. Therefore, it can be used as a marker in lower gastrointestinal tumors. In this study; Detection of SATB2 and MMR proteins by immunohistochemical method, evaluation of tumors with MMR protein deficiency in terms of location, histological subtype, age, gender, tumor stage, survival, crohn-like lymphoid reaction, lymphocytes infiltrating the tumor, lymphovascular invasion and perineural invasion, again We aimed to investigate the relationship of SATB2 expression with age, gender, histological subtypes, tumor stage, survival, lymph node metastasis, distant organ metastasis, lymphovascular invasion and perineural invasion, as well as the relationship between SATB2-MSI. Our study included 150 patients who were diagnosed with colon adenocarcinoma and did not receive neoadjuvant treatment, who were referred to Dicle University Faculty of Medicine, Department of Pathology between January 01, 2010 and August 30, 2020. 8 According to statistical data, dMMR; right colon location, tumor infiltrating lymphocytes, Crohn's-like lymphocytic response were found to be significantly associated with the literature. In our study, a statistically significant relationship was observed between SATB2 negative tumors and high histological grade, high stage and low survival rate. In our study, SATB2 negative and SATB2 low expression cases were observed at a higher rate in the dMMR group compared to the MSS group, and it was found to be statistically significant. We think that immunohistochemical parameters MLH-1, MSH-2, MSH-6, PMS-2 that can be routinely applied in colon adenocarcinomas can be a quick way to predict MSI, MSI detection will help in clinical follow-up and treatment planning of patients, and SATB2 expression is a positive prognostic factor in colon cancers. In addition, we think that the relationship between the presence of dMMR and negative SATB2 expression is associated with survival, should be considered when evaluating the patient, and has an important role in guiding the treatment.