The protein tyrosine phosphatase receptor type H, PTPRH, is differentially expressed in the primary tumors of breast cancer patients treated with trastuzumab.

Abstract

Trastuzumab, a monoclonal antibody targeted against the human epidermal growth factor receptor 2 (HER2) is utilized for the treatment of human breast cancer (1, 2), but a complete understanding of how tumor signal transduction is modulated by trastuzumab treatment is lacking. By mining published and public microarray and gene expression data (3, 4) from the primary tumors of patients treated with trastuzumab, we found that the protein tyrosine phosphatase receptor type H, encoded by PTPRH, was among the genes most differentially expressed in the primary tumors of patients treated with trastuzumab, and expressed at lower levels in the tumors of patients treated with trastuzumab. Thus, the use of trastuzumab in patients with breast cancer is associated with decreased primary tumors expression of a protein tyrosine phosphatase whose deficiency in pediatric solid tumors defines a risk-phenotype (5) and whose expression is decreased in colorectal cancer (6).