Objective      To determine the expression profile and distribution of myeloid differentiation factor 88 (MyD88) in breast carcinomas and adjacent normal tissues to investigate the role of innate immune factors downstream signaling in the breast carcinoma.       Methods      Clinical data of 35 cases of pathologically diagnosed breast carcinomas who received radical resection in our department during January 2010 to September 2011 were collected in this study. RT-PCR and Western blot analysis were used to detect the expression of MyD88 at mRNA and protein levels in the breast carcinomas and adjacent normal tissue. Immunohistochemical assay was employed to study the distribution of MyD88 in these tissues for its expression profile and variation.       Results      RT-PCR showed that the expression rate of MyD88 was significantly increased in breast carcinoma

with statistically significant compared to adjacent normal tissues (P0.01). Western blot analysis displayed similar results in protein expression of MyD88 in the two tissues (P0.01). MyD88 was also mildly expressed in adjacent normal tissues

with some cells displaying weakly positive expression. In contrast

breast carcinoma tissue showed strong expression. The expression of MyD88 was differential in different cell types

and was closely related to TNM stages

tumor size

lymphatic invasion and metastasis.       Conclusion      MyD88 may play a regulatory role in breast cancer incidence and development process.