Abstract 2179: The role of ATP-binding cassette transporter A5 in colorectal cancer progression

Abstract Background: Colorectal cancer (CRC) is one of the most common malignancies worldwide; it is the fourth leading cause of cancer-related deaths. The lack of novel diagnostic and therapeutic targets and the development of chemoresistance are major issues when dealing with CRC. The overexpression of ATP-binding cassette (ABC) transporters is considered one facilitating mechanism for chemoresistance. Furthermore, several ABCA superfamily transporters have been shown to mediate cancer development and multidrug resistance. However, the role of ABCA5 in CRC development and progression is elusive. The current study aimed at profiling the expression of ABCA5 at the different grades of CRC. Experimental Methods: Forty-nine (9 Well differentiated, 26 moderately differentiated and 14 poorly differentiated) primarily diagnosed CRC cases, and 15 normal colonic tissues were included in the study. Formalin-fixed paraffin-embedded samples were interpreted for the differential expression of ABCA5 by immunohistochemistry. The immunoreactivity of ABCA5 was assessed in the cells based on the staining intensity and the percentage of the positively stained cells to create the immunoreactive score. Results: In total, 49 CRC cases were recruited, with a mean age of 63.77 years (range 33-86); 21 female and 28 male patients. All specimens were diagnosed as adenocarcinoma (NOS). Immunohistochemical analysis of the 49 CRC samples revealed diffuse ABCA5 immunoreactivity in the majority of cases. Seven cases showed mild expression, 25 showed moderate expression, whereas 17 cases revealed intense ABCA5 expression. Intriguingly, negative to a mild expression of ABCA5 was noted in the normal colonic tissues. ABCA5 intensity was higher in poorly differentiated CRC compared to the other grades. Conclusion: Higher expression of ABCA5 is associated with CRC differentiation, indicating that it might contribute to CRC development and progression. Thus, it may be a novel diagnostic biomarker. Citation Format: Khuloud Bajbouj, Latifah Alketbi, Qutayba Hamid, Iman Talaat. The role of ATP-binding cassette transporter A5 in colorectal cancer progression [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2179.