Certain combinations of genes that encode receptors on innate immune cells increase the risk of developing cervical cancer, according to a study by Mary Carrington and colleagues in the April 4 issue of The Journal of Experimental Medicine. Most cervical cancers (>95%) are associated with human papillomavirus (HPV), which establishes chronic infections in the genital tract. Immune cells called natural killer (NK) cells, known in part for their ability to kill tumor cells, are found in HPV-positive cervical lesions and might help determine the outcome of virus infection and the potential for progression to cancer. Activation of NK cell activation depends on a balance between activating and inhibitory signals generated by a group of protein receptors called killer cell immunoglobulin-like receptors (KIRs). These receptors bind to partner proteins that are expressed on virtually all cell types. Carrington and colleagues found that individuals who have more inhibitory than activating KIRs had a decreased risk for cervical cancer, suggesting that activation of NK cells contributes to cancer progression. NK cell activation may increase local inflammation, suggests Carrington, which has been associated with the progression of other types of cancer including gastric and prostate cancer. Exactly how inflammation might promote cervical cancer remains unknown.
