Sialic (Neuraminic) Acid Residues Detection in Pulmonary Adenocarcinomas: A Digital Assessment

Glycocalyx on the cell surfaces interacts with adjacent cells and the endothelium. Neoplastic cellular changes are known to affect the glycocalyx and the “stickiness” of the cell surface. We hypothesize that the sialyl residue expression is differentially altered in pulmonary adenocarcinoma and this change affects their invasiveness. In this study, we quantitatively assessed sialic acid residues in pulmonary adenocarcinomas by utilizing a sialyl recognizing Trithrichomonas mobililensis lectin (TML). Biotinylated lectin binding was detected in 24 subjects. The TML reacted paraffin sections of resected pulmonary adenonocarcinomas, were digitized at constant illumination with IMT4 CCD Camera and the images were morphometrically evaluated with the Olympus Analysis Program. For more precise estimation of the reaction product on TML, we reduced the blue signal and accentuated the red one in all images equally with ADOBE Photo Shop Elements 2.0. The edited images had a sharper definition of the reaction product and allowed a more precise measurement of the sialic acid residues in the area of interest after subtraction of airspaces background from the measured tissue area. Detected sialic acid ranged from 0.5% to 3.3% of the examined tissue. Pulmonary adenocarcinomas are recognized as having considerable pleomorphism, as well as mixture of subtypes. We examined the relationship of sialic acid abundance with histopathologic tumor pattern and TNM ( T umor, N odes, M etastasis) classification. The early stages of tumors, having the lepidic, papillary and acinar patterns in stages 0, I & II with no metastasis, tended to have high, >.5% of detected sialyl residues. The low, <0.5% expression of sialic acid was found to be correlated with the invasive subtypes; the micropapillary, mixed and solid patterns in stages III and IV. These results indicate that the sialyl residue abundance was inversely correlated with the invasiveness and the stage of adenocarcinoma. We conclude that the sialic acid residues as detected with the TML, maybe an important determinant of the tumor invasiveness and an adjuvant for a more objective determination of the cell glycocalyx transformation for staging the pulmonary adenocarcinoma. Support or Funding Information NSU Faculty Research Grant. This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .