Upregulation of Breast Cancer Resistance Protein Expression was Decreased in Plasma Membrane of Colon Cancer with Metastasis of Lymphatic Node.

Background: ATP-binding cassette sub-family G member 2 (ABCG2), an ABC transport protein involved in the efflux of anticancer compounds, has been reported to have altered expression levels in several cancers including breast, colon, and gastric cancer, etc. However, its expression change (up- or down-regulated in cancer) is still contradictory.

Methods: We performed immunohistochemistry to examine ABCG2 expression in the microarray with 90 pairs of colon cancer and their adjacent normal tissues. To find the expression of ABCG2 in lymphatic node metastasis (N1) and N0, we performed immunofluorescence, analyzed by Confocal technology.

Results: Compared to adjacent normal tissues, the percentage and density of positive cells expressing ABCG2 in colon cancer were significantly increased. In addition, ABCG2 expression in plasma membrane was related to lymph node metastasis in colon cancer, which was further verified to be downregulated by 2.7-fold in N1 to N0 through immunofluorescent analysis.

Conclusions: ABCG2 expression in colon cancer was up-regulated, and its expression was decreased in the plasma membrane of colon cancer with lymphatic node metastasis (N metastasis).