Partial Oxygen Pressure Affects the Expression of Prognostic Biomarkers HIF-1 Alpha, Ki67, and CK20 in the Microenvironment of Colorectal Cancer Tissue

Abstract

Hypoxia is prognostically important in colorectal cancer (CRC) therapy. Partial oxygen pressure (pO2) is an important parameter of hypoxia. The correlation between pO2levels and expression levels of prognostic biomarkers was measured in CRC tissues. Human CRC tissues were collected and pO2levels were measured by OxyLite. Three methods for tissue fixation were compared, including formalin, Finefix, and Finefix-plus-microwave. Immunohistochemistry (IHC) staining was conducted by using the avidin-biotin complex technique for detecting the antibodies to hypoxia inducible factor-1 (HIF-1) alpha, cytokeratin 20 (CK20), and cell proliferation factor Ki67. The levels of pO2were negatively associated with the size of CRC tissues. Finefix-plus-microwave fixation has the potential to replace formalin. Additionally, microwave treatment improved Finefix performance in tissue fixation and protein preservation. The percentage of positive cells and gray values of HIF-1 alpha, CK20, and Ki67 were associated with CRC development (P<0.05). The levels of pO2were positively related with the gray values of Ki67 and negatively related with the values of HIF-1 alpha and CK20 (P<0.05). Thus, the levels of microenvironmental pO2affect the expression of predictive biomarkers HIF-1 alpha, CK20, and Ki67 in the development of CRC tissues.