The clinicopathological significance of SPOP (speckle type protein) protein in high grade serous carcinoma cases

High grade serous carcinoma (HGSC) is the most common epithelial ovarian cancer. It originates from precursor lesions located at the fimbrial end of the fallopian tube and has a complex genomic structure. Speckle type POZ protein (SPOP) regulates intracellular protein degradation. The mutated SPOP gene support carcinogenesis by causing dysregulation of the intracellular protein homeostasis. SPOP gene mutations and protein expression abnormalities have been detected in different cancers. SPOP gene alterations have been reported in HGSC's. However, the relationship between SPOP expression and clinicopathological parameters is not well documented in HGSC cases. SPOP protein is responsible for degradation of programmed cell death ligand 1(PD-L1), which is responsible for maintaining immune homeostasis. There are conflicted data on PD-L1 expression of HGSC cases, and its relationship with the SPOP protein has not yet been evaluated. In our study, we aimed to determine the expression of SPOP protein in HGSC cases, and to investigate the relationship between SPOP expression and PD-L1 expression, the effect of SPOP expression on clinicopathological features and prognosis. Seventy patients diagnosed with HGSC between 2010 and 2023 were included in the study. Low SPOP expression was detected in most of the cases immunohistochemically. Low SPOP expression was significantly associated with PD-L1 CPS positivity. No association was found between SPOP expression and clinicopathological features, recurrence free survival, overall survival and PD-L1 TPS values. Additional studies are needed to reveal the role of SPOP expression in carcinogenesis of HGSC cases, its prognostic significance, the relationship with PD-L1 status and clinicopathological features. Key Words: SPOP, high grade serous carcinoma, PD-L1, ovary