Abstract 3178: A research tool for elucidating the interaction between human mucin 16 (CA125) and immune cells in ovarian cancer

CA125 represents the circulating subunit of the large transmembrane glycoprotein MUC 16. Elevated levels of CA125 are suggestive of ovarian cancer and the magnitude of elevation correlates with burden of disease. A rising CA125 level after treatment suggests cancer recurrence. Ovarian tumor cells produce and shed MUC 16 which can bind to certain peripheral immune cells. To study this, current techniques use labelled-fluorescent markers that bind to CA125 on cells and flow cytometry to detect mean fluorescence. A limitation is that this technique may not be able to distinguish low-binding events from autofluorescence. Our new technology improves the resolution for studying CA125 bound to immune cells by employing antibody-labelled gold nanoparticles with far-greater sensitivity than fluorescent markers. The cells are then examined using darkfied microscopy rather than flow, which also permits automated slide scanning and focusing for 3-dimensional counting. This enables both simultaneous use of fluorescent markers to identify the immune cell populations as well as automated image analysis to quantify the amount of bound CA125 on individual cells. Preliminary data show that MUC 16 is preferentially bound to NK and T cells in women with ovarian cancer compared to binding in healthy controls. These insights may help elucidate the function of CA125 in ovarian cancer and improve our understanding of immune-tumor interactions. Citation Format: Kornel Lakatos, Petra Krauledat, German Gonzalez Serrano, Peter Hansen, Daniel William Cramer, Kevin Elias, Manish Patankar, Jawad Hoballah. A research tool for elucidating the interaction between human mucin 16 (CA125) and immune cells in ovarian cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 3178.