Downregulation of Hematopoietic Progenitor Kinase 1 Protein Level in Ductal Carcinoma In Situ and Invasive Ductal Carcinoma of Breast
S Chen, C Albarracin, H Wang, K Klein, A Sahin, HM Wang. The University of Texas MD Anderson Cancer Center, Houston, TX; The University of Texas at Houston, Houston, TX
Background: Hematopoietic progenitor kinase 1 (HPK1) regulates stress response, proliferation, and apoptosis in hematopoietic cells. The role of HPK1 is not well studied in solid tumors. Recent study in our lab showed that the loss of HPK1 is associated with the progression of pancreatic intraepithelial neoplasm and invasive pancreatic ductal adenocarcinoma, and it may contribute to the tumorigenesis of pancreatic cancer. In this study, we will examine the HPK1 protein expression during the development of invasive ductal carcinoma of the breast.
Design: Forty three cases of normal breast tissue, thirty two cases of ductal carcinoma in situ (DCIS), and forty nine cases of invasive ductal carcinoma (IDC) were collected from formalin-fixed, paraffin-embedded archival tissue blocks. HPK1 protein level was evaluated by immunohistochemical staining. Tumors or benign breast tissue with no or only focal cytoplasmic staining for HPK1 (<5% of the cells) was regarded as negative. Tumors or benign breast tissue with cytoplasmic staining for HPK1 (>5% of the cells) was regarded as positive.
Results: 29/43 normal breast tissue (67.4%) show positive staining of HPK1 protein in the normal ductal epithelial cells. In contrast, only 6/32 DCIS (18.7%) show positive staining (P<0.0001) and 8/49 IDC (16.3%) show positive staining (P<0.0001). HPK1 is lost in DCIS and IDC, particularly in those with higher grade lesion.
Conclusions: We demonstrated that HPK1 protein is lost in a high percentage of DCIS and IDC compared to the normal ductal epithelial cells. These results suggest that loss of HPK1 protein may play a role in the oncogenesis of the breast cancer.
Wednesday, March 24, 2010 1:00 PM
Poster Session VI # 13, Wednesday Afternoon