Haptoglobin Expression in Endometrioid Adenocarcinoma of the

Objective: Elevated serum haptoglobin (Hp) concentrations have been reported in patients with malignant diseases. We have shown that Hp is produced by and localizes only in the stroma and not the epithelium of endometriotic lesions, which share many characteristics of carcinoma. Furthermore, Hp mRNA and protein are found exclusively in the stroma of eutopic endometrium from women with endometriosis and not those without endometriosis. We hypothesized that characteristic patterns of Hp gene expression and protein localization in endometrioid adenocarcinoma of the uterus may provide insight into the clinical utility of Hp as a tumor marker or alternative therapeutic approach. Methods: Biopsies of endometrioid adenocarcinoma tumors of the uterus and their adjacent nonaffected endome-trium were collected. Normal endometrium was collected from healthy women. Haptoglobin messenger RNA (mRNA) levels were quantified by quantitative polymerase chain reaction (Q-PCR). Haptoglo-bin protein cell-specific localization was identified by immunohistochemistry. Results: Haptoglobin mRNA levels were significantly greater (P <.005) in endometrioid adenocarcinoma and adjacent non-affected endometrial tissues than normal endometrium. No correlation was found between Hp levels and cancer stage (P .673) or grade (P .739). Haptoglobin protein localized in both stromal and gland-ular epithelial cells of endometrioid adenocarcinoma and their adjacent nonaffected tissue but not in control endometrium. Conclusions: Our results have identified, for the first time, unique patterns of Hp mRNA expression and protein localization in the stromal and glandular epithelial cells of endometrioid adenocarci-noma of the uterus.We propose that this unique pattern of endometrioid adenocarcinomaHp expression may be developed as a novel diagnostic marker. Modulation of Hp, with its immunomodulatory and angiogenic properties, may generate novel methods of prevention or treatment for endometrial cancer. KEY WORDS: Haptoglobin, endometrioid adenocarcinoma, endometrium, tumor marker.