Purpose: Impaired IFNγ production in peripheral blood lymphocytes (PBL) and their subsets reflects immunosuppression and inadequate antitumor immune response in cancer patients. Decreased function of natural killer (NK) cells has not been investigated in breast cancer with respect to altered pSTAT signaling pathways.
Methods: PBL of breast cancer patients and healthy controls were analyzed for IFNγ and pSTAT1 expression and NK cell activity using flow cytometry and (51)Cr-release assay, respectively. The level of pSTAT1, 3 and 5 was investigated by Western blotting.
Results: Our results indicated that PBL and CD3(-) CD16(+) NK cells of patients had significantly lower level of IFNγ. The patients had a significantly decreased NK cell cytotoxicity compared to controls, with the decrease being dependent on the stage of disease. Positive correlation between IFNγ level in PBL and NK cytotoxicity in controls and patients was also shown. The PBL of patients, compared to controls, expressed lower level of pSTAT1, 3 and 5. The patients' T and NK cell subsets had lower pSTAT1 level.
Conclusion: This study indicates that pSTAT1 in PBL of breast cancer patients could be a biomarker of decreased NK cell cytotoxicity and IFNγlevel that are associated with progression of this disease.