Immunohistochemical Analysis of a1-Acid Glycoprotein and Tumor Associated Macrophages in Clear Cell Renal Cell Carcinoma.

Abstract

Background/aim: α1-Acid glycoprotein (AGP), also known as orosomucoid, is an acute-phase protein that has been found increased in plasma of cancer patients. This study investigates the role of AGP expression in clear cell renal cell carcinoma (ccRCC) and its association with clinical outcomes.

Materials and methods: We investigated the correlation between AGP levels and the prognosis of ccRCC through an analysis of The Cancer Genome Atlas (TCGA) database. To examine AGP expression and its clinicopathological associations, immunostaining was performed on paraffin-embedded tissue samples of 92 ccRCC cases.

Results: AGP expression was found to be higher in RCC cell lines compared to normal renal epithelial cells. Analysis of the TCGA dataset showed that patients with AGP gene expression had significantly worse overall survival. However, AGP expression was not correlated with age, sex, or cancer stage. A mouse monoclonal antibody against AGP was generated. This antibody reacted with human and mouse hepatocytes, but not in AGP-deficient mice. From 92 examined ccRCC cases, AGP protein expression was detected in 89 cases, with only 3 being negative. AGP expression levels did not correlate with clinicopathological factors, such as age, tumor size, or nuclear grade. CD14, a receptor of AGP, was found to be expressed in Iba1-positive monocytes and tumor-associated macrophages (TAMs) but not in other cell types like lymphocytes or cancer cells. No significant correlation was found between AGP expression and the number of Iba1-positive cells in ccRCC tissues. Iba1-positive cells were correlated with Fuhrman grade, and patients with ≥30% Iba1-positive cells were, on average, significantly younger and had more aggressive tumor.

Conclusion: AGP expression is linked to poorer survival in ccRCC, but its association with immune cell infiltration (via Iba1-positive cells) is unclear.