High MICB expression as a biomarker for good prognosis of colorectal cancer

Major histocompatibility complex (MHC) plays an important role in colorectal cancer (CRC) immunity. However, the function of MHC class I chain-related B (MICB) molecule is not very clear. In this study, we explored the prognostic effect of MICB in colorectal cancer.

From 2008-05 to 2012-11, consecutive CRC patients of Zhongshan Hospital, Fudan University were retrospectively enrolled as primary cohort. The inclusion criteria were as follows: receiving primary radical resection, pathologically confirmed colorectal adenocarcinoma, no treatment before surgery, clinicopathological data available. Another cohort of CRC patients were collected from a public dataset GSE39582 of GEO database from 1987 to 2007 in the same criteria for validation. MICB was detected using immunochemistry and evaluated as prognostic biomarker. The cut-off value of MICB expression was calculated using X-tile software.

Finally, 863 patients were enrolled in the primary cohort, and 556 patients were enrolled in the validation cohort. MICB expression was significantly associated with tumor size and primary histological type in primary cohort, and with primary tumor location and distant metastases in validation cohort. The survival analysis showed that patients with high MICB expression had significantly better overall survival in both primary (P = 0.002) and validation (P = 0.001) cohorts. The multivariate analysis also confirmed that high MICB expression was a significantly independent protective factor for overall survival in both primary (hazard ratio HR = 0.741, 95% CI 0.594-0.924) and validation (HR = 0.699, 95% CI 0.508-0.961) cohorts.

For stage I-IV CRC patients, MICB was confirmed a novel independent prognostic factor. It could help better stratification of CRC prognosis.