Increased levels of mannose-6-phosphate/insulin-like growth factor 2 receptor (M6P/IGF2-R) found in serum of patients with breast cancer

Abstract

The multifunctional transmembrane mannose-6-phosphate/insulin-like growth factor-2 receptor (M6P/IGF2-R) has been proposed as a putative prognostic marker in breast cancer. Loss of heterozygosity (LOH) with mutations in the remaining allele have been described at the gene level. We previously reported significant decrease of M6P/IGF2-R at the protein level in cancer cells than normal peritumoral ducts of breast tumors which may indicate an increased release of the receptor from the cell membrane to the blood. To assess that hypothesis we measured in this study M6P/IGF2-R levels in serum of women with breast cancer by competitive enzyme-linked immunosorbent assay (ELISA) that allows a detectable sensitivity of 300 ng/mL. The results were obtained referring to a standard curve consisting in varying concentrations of human purified M6P/IGF2-R. Women sera consisted of cancer-free sera (n=39) or serum from women with breast cancer (n=39) were preincubated with anti-M6P/IGF2-R immunoglobulin Y (IgY) antibodies. High levels of M6P/IGF2-R (p<0.01) were found in serum from women with breast cancer in comparison with cancer-free serum. Overall the results support the hypothesis of increased release of the receptor from cancer cells to the blood and add one more argument for M6P/IGF2-R studying as a potential breast cancer marker.   Key words: Mannose-6-Phosphate/Insulin-like Growth Factor-2 Receptor (M6P/IGF2-R), loss of heterozygosity (LOH), suppressor gene, breast cancer, competitive enzyme-linked immunosorbent assay (ELISA), IgY, biological marker.