A circulating microvesicle-based biosignature for the detection of colorectal cancer

373

Background: Microvesicles are principally derived either from the endosomal pathway (as exosomes) or shed directly from the plasma membrane. They are between 40-500 nm in diameter and are secreted by most cell types, including tumor cells. In circulation, microvesicles appear to participate in cellular communication by transporting mRNAs, miRs and proteins from their cell of origin to target cells where they can elicit biological responses. The quantity and protein topography of microvesicles shed from cancer cells varies considerably compared to those shed from normal cells. Thus, the concentration of circulating plasma microvesicles with molecular markers indicative of the disease state can be used as a robust and informative blood-based biosignature. In this study we report the results of the application of a novel multiplexed method for quantifying and profiling microvesicles in plasma for the detection of colorectal cancer.

Methods: We have developed a versatile mulitplexed microvesicle-based discovery panel with 73 different antibodies that target surface proteins of various microvesicle subpopulations. This system was used to develop a microvesicle-derived biosignature composed of 2 different surface membrane protein biomarkers.

Results: In this study, we demonstrate that a combination of TMEM211 and CD24 provide a robust signature for the detection of colorectal cancer (CRC). We isolated microvesicles from plasma of 257 patients with CRC, 57 stage I, 104 stage II, 80 stage 3, 6 stage IV, and 11 of unknown stage; 327 self-described, age-range matched normal plasma specimens were used for the control population. The level of TMEM211 and CD24 containing microvesicles for these samples was determined using a multiplexed immunoassay. Thresholds were empirically determined to maximize the sensitivity and specificity of CRC detection, resulting in a sensitivity of 90% with a specificity of 85% with an AUC of .91.

Conclusions: This study demonstrates that it is possible to use circulating microvesicles for the development of a highly sensitive and specific blood-based assay to detect CRC.

[Table: see text]