Objective: This study investigated the incidence and clinical significance of homeodomain-interacting protein kinase 1 expression in breast cancer patients. Methods: We investigated immunohistochemical homeodomain-interacting protein kinase 1 expression from tissue microarrays of 1032 patients. The association of homeodomain-interacting protein kinase 1 expression pattern, clinicopathologic factors and survival outcome was evaluated. Tumors with ≥10% stained cells were considered positive for homeodomain-interacting protein kinase 1. Results: Non-cancerous breast tissue, pTis and pT1mic lesions did not show homeodomain-interacting protein kinase 1 expression at any sites. Of the 859 invasive tumors, 124 (14.4%) showed homeodomain-interacting protein kinase 1 expression with three different expression patterns: cytoplasmic (2.4%), nuclear (6.3%), and both cytoplasmic and nuclear (5.7%). Cytoplasmic homeodomain-interacting protein kinase 1-positive tumors showed distinctive features such as fewer nodal metastases, but were frequently Grade III, estrogen receptor-negative, progesterone receptor-negative, HER2-positive, highly proliferative and molecular apocrine tumors. No significant difference in clinicopathologic features was identified between negative and nuclear homeodomain-interacting protein kinase 1-positive tumors. Both cytoplasmic and nuclear HIPK1-positive tumors represent frequent small size, node negativity and moderately differentiated features. Survival was not significantly different by homeodomain-interacting protein kinase 1 expression patterns. Conclusions: Homeodomain-interacting protein kinase 1 expression was identified only in invasive breast cancer cells with three different patterns: cytoplasmic, nuclear, and both cytoplasmic and nuclear. Although the mechanism is not certain, the subcellular localization of HIPK1 expression is associated with tumor histopathologic characteristics and different functions.
All Science Journal Classification (ASJC) codes
- Radiology Nuclear Medicine and imaging
- Cancer Research