KLRB1 gene expression is suppressed in human cancer tissues

The KLRB1 gene encodes the CD161 receptor in natural killer cells (NK cells). The gene is also expressed in the NKT cells. Both types of cells are cytotoxic and capable of recognizing and eliminating various tumor, virus-infected, and allotransplant cells. The biological function of human CD161 is not clear. It is suggested that it can be involved in the regulation of both cytotoxic cell functions and cytokine production. As the majority of cancer patients show down-regulation of the immune system, we hypothesized that the level of KLRB1 expression might also be suppressed in cancer cells. Here, we show that KLRB1 gene expression was suppressed in tumor tissues in 68% of patients with non-small-cell lung cancer (p < 0.0001) and in 57% of patients with esophageal squamous-cell carcinoma (p = 0.0003). The high frequency of KLRB1 gene suppression in cancer patients suggests that this gene can represent a highly informative marker of lung and esophageal cancers.