The role of the organic anion transporting polypeptide OATP4A1 in immunactivation in colorectal cancer and inflammatory colon disease.

481 Background: OATP-transporter proteins, such as OATP4A1, present influence cancer progression by providing compounds (hormones, prostaglandins, cyclic nucleotides, second messenger proteins, drugs) which either inhibit or stimulate tumor cells growth. Therefore, OATP expression in cancer cells and in the stroma, i.e., the microenvironment surrounding the epithelial cells can become a critical parameter. Methods: OATP4A1 was investigated in paraffin-embedded specimens from 148 patients with colorectal cancer and 20 with diverticulitis by immunohistochemistry (IHC) on an automatic quantitative microscopic image analysis system (TissuesFaxs). With the Histoquest program, the immunoreactive score (IRS), was calculated from the degree of the staining intensity and the number of OATP4A1-positive cells. To identify OATP4A1+-cells, double-immunofluorescence staining (IF) was done with antibodies against appropriate cellular markers. Results: OATP4A1 was located in the membrane and cytosol of colon cancer cells...