Expression and clinicopathological significance of FSIP1 in breast cancer

Abstract

AimTo investigate the clinicopathological significance of the expression of fibrous sheath interacting protein 1 (FSIP1) in breast cancer, serum samples, and wound fluid from patients with breast cancer.MethodsWound fluid and serum samples from female patients with primary breast cancer, recurrent and metastatic breast cancer, and benign tumors were analyzed for FSIP1 expression using ELISA. 286 paraffin-embedded surgical specimens from breast cancer patients with at least 5 years of follow-up were included for FSIP1 expression assay using immunohistochemistry.ResultsExpression of FSIP1 protein was significantly higher in breast cancer tissues compared to tumor-adjacent tissues (p = 0.001). Strong correlation was observed between FSIP1 expression and human epidermal growth factor receptor 2 (Her-2) or Ki67 expression in breast cancer (p = 0.027 and 0.002, respectively). Similarly, serum level of FSIP1 was higher in patients with recurrent and metastatic breast cancer compared to that of primary breast cancer (7, 713 ± 3, 065 vs. 4, 713 ± 3, 065 pg/ml, p = 0.003). Finally, patients with high FSIP1 expression showed a worse post-operative disease-specific survival (p = 0.024).ConclusionFSIP1 may play an important role in the tumorigenesis and invasion of breast cancer and is a potential biomarker for breast cancer diagnosis or prognosis.

FSIP1 binds HER2 directly to regulate breast cancer growth and invasiveness

“…Nonetheless, some patients fail targeted therapy and/or experience recurrence, prompting the continuing search for new prognostic markers (2). Confirming previous data (3), our group recently documented that the testicular antigen fibrous sheath interacting protein 1 (FSIP1) was expressed abundantly in breast cancer tissues (4), and that its abundance is correlated positively with HER2 expression and tumor invasiveness and negatively with disease-specific survival (5).…”

“…In fact, normal breast tissue surrounding the cancer does not express FSIP1 to any appreciable extent (5). In breast cancer tissue, however, FSIP1 expression correlates with HER2-positivity and Ki67 expression (5).…”

“…We and others have shown previously that the testicular, spermatogenesis-related antigen FSIP1 is expressed in abundance in various cancers, including multiple myeloma, prostate cancer, and breast cancer (4)(5)(6)8), whereas it is clear from extensive RNA-sequencing studies that only normal testes and pituitary express FSIP1 (https://gtexportal.org/home/gene/FSIP1). In fact, normal breast tissue surrounding the cancer does not express FSIP1 to any appreciable extent (5).…”

“…HER2-overexpressing SKBR3 cells thus display higher FSIP1 levels than MCF-7 cells (5). Second, FSIP1 expression is notably higher in breast cancer tissue with high Ki67 expression, indicating a correlation with cell proliferation (5). Third, FSIP1 is detectable in the serum of breast cancer patients, and high serum FSIP1 is associated with worse postoperative disease-specific survival (5).…”

“…Second, FSIP1 expression is notably higher in breast cancer tissue with high Ki67 expression, indicating a correlation with cell proliferation (5). Third, FSIP1 is detectable in the serum of breast cancer patients, and high serum FSIP1 is associated with worse postoperative disease-specific survival (5). Finally, with the exception of the testes and pituitary, FSIP1 displays limited expression in noncancerous tissues, including normal breast (https://gtexportal.…”