Galectin binding proteins in serum and bronchoalveolar lavage -in healthy and pathological conditions

Abstract: Galectins are carbohydrate binding proteins, implicated in conditions of both inflammation and cancer. Connections between chronic inflammation and cancer are proposed by the increased remodelling and proliferation that occurs, leading to enhanced survival and proliferation of malignant cells. Since galectins have been implicated in mechanisms of both chronic inflammation and cancer, we have investigated natural binding partners of galectins in healthy individuals and then continued with studying states of cancer and chronic inflammation. We identified galectin binding glycoproteins in sera from healthy individuals and found that galectins widely expressed in the body bind serum glycoproteins well, whereas galectins with a more tissue-specific distribution scarcely binds any serum glycoproteins. We then chose the widely expressed but intermediately binding galectin-1 to detect if levels of galectin-1-binding proteins are increased in sera of breast cancer patients. We found that galectin-1 binds approximately double the amount in breast cancer patients compared to healthy individuals. The increase was mainly caused by haptoglobin, probably due to both increased expression and changes of glycosylation. To further investigate the inflammatory connection we identified galectin binding proteins from bronchoalveolar lavage of asthma patients and healthy individuals, additionally we compared the binding of galectin-3 and galectin-8 that are expressed in different sites of the lung. We found when functionally grouping the bound proteins that galectin-3 and -8 binding proteins had different profiles and that bound proteins of healthy and asthma patients differed.